Environmental Protection Agency

40 CFR Part 131

[EPA-HQ-OW-2009-0596; FRL-XXXX-X]

[RIN 2040-AF11] 

 Water Quality Standards for the 

State of Florida’s Lakes and Flowing Waters

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed Rule.

SUMMARY: The Environmental Protection Agency (EPA) is proposing numeric
nutrient water quality criteria to protect aquatic life in lakes and
flowing waters, including canals, within the State of Florida and
proposing regulations to establish a framework for Florida to develop
“restoration standards” for impaired waters.  On January 14, 2009,
EPA made a determination under section 303(c)(4)(B) of the Clean Water
Act (“CWA” or “the Act”) that numeric nutrient water quality
criteria for lakes and flowing waters and for estuaries and coastal
waters are necessary for the State of Florida to meet the requirements
of CWA section 303(c).  Section 303(c)(4) of the CWA requires the
Administrator to promptly prepare and publish proposed regulations
setting forth new or revised water quality standards (“WQS” or
“standards”) when the Administrator, or an authorized delegate of
the Administrator, determines that such new or revised WQS are necessary
to meet requirements of the Act.  This proposed rule fulfills EPA’s
obligation under section 303(c)(4) of the CWA to promptly propose
criteria for Florida’s lakes and flowing waters.

DATES:  Comments must be received on or before [insert date], 60 days
after publication in the Federal Register. 

ADDRESSES: Submit your comments, identified by Docket ID No.
EPA-HQ-OW-2009-0596, by one of the following methods:

  HYPERLINK "http://www.regulations.gov"  www.regulations.gov :  Follow
the on-line instructions for submitting comments.

Email: ow-docket@epa.gov

Mail to: Water Docket, U.S. Environmental Protection Agency, Mail code:
2822T, 1200 Pennsylvania Avenue, NW, Washington, DC 20460, Attention:
Docket ID No. EPA-HQ-OW-2009-0596.

Hand Delivery: EPA Docket Center, EPA West Room 3334, 1301 Constitution
Avenue, NW, Washington, DC 20004, Attention Docket ID No.
EPA-HQ-OW-2009-0596.  Such deliveries are only accepted during the
Docket’s normal hours of operation, and special arrangements should be
made for deliveries of boxed information.

Instructions: Direct your comments to Docket ID No. EPA-HQ-OW-2009-0596.
 EPA’s policy is that all comments received will be included in the
public docket without change and may be made available online at  
HYPERLINK "http://www.regulations.gov"  www.regulations.gov , including
any personal information provided, unless the comment includes
information claimed to be Confidential Business Information (CBI) or
other information whose disclosure is restricted by statute.  Do not
submit information that you consider to be CBI or otherwise protected
through   HYPERLINK "http://www.regulations.gov"  www.regulations.gov 
or e-mail.  The   HYPERLINK "http://www.regulations.gov" 
www.regulations.gov  Web site is an “anonymous access” system, which
means EPA will not know your identity or contact information unless you
provide it in the body of your comment.  If you send an e-mail comment
directly to EPA without going through   HYPERLINK
"http://www.regulations.gov"  www.regulations.gov  your e-mail address
will be automatically captured and included as part of the comment that
is placed in the public docket and made available on the Internet.  If
you submit an electronic comment, EPA recommends that you include your
name and other contact information in the body of your comment and with
any disk or CD-ROM you submit.  If EPA cannot read your comment due to
technical difficulties and cannot contact you for clarification, EPA may
not be able to consider your comment.  Electronic files should avoid the
use of special characters, any form of encryption, and be free of any
defects or viruses.  For additional information about EPA’s public
docket visit the EPA Docket Center homepage at   HYPERLINK
"http://www.epa.gov/epahome/dockets.htm" 
http://www.epa.gov/epahome/dockets.htm . 

Docket: All documents in the docket are listed in the   HYPERLINK
"http://www.regulations.gov"  www.regulations.gov  index.  Although
listed in the index, some information is not publicly available, e.g.,
CBI or other information whose disclosure is restricted by statute. 
Certain other material, such as copyrighted material, will be publicly
available only in hard copy.  Publicly available docket materials are
available either electronically in   HYPERLINK
"http://www.regulations.gov"  www.regulations.gov  or in hard copy at a
docket facility.  The Office of Water (OW) Docket Center is open from
8:30 until 4:30 p.m., Monday through Friday, excluding legal holidays. 
The OW Docket Center telephone number is (202) 566-2426, and the Docket
address is OW Docket, EPA West, Room 3334, 1301 Constitution Avenue, NW,
Washington, DC 20004.  The Public Reading Room is open from 8:30 a.m. to
4:30 p.m., Monday through Friday, excluding legal holidays.  The
telephone number for the Public Reading Room is (202) 566-1744.  

Public hearings will be held in the following cities in Florida: 
Tallahassee, Orlando, and West Palm Beach.  The public hearing in
Tallahassee is scheduled for Tuesday, February 16, 2010 and will be held
from 1:00 p.m. to 5:00 p.m. and 7:00 p.m. to 10:00 p.m. at the Holiday
Inn Capitol East, 1355 Apalachee Parkway, Tallahassee, FL 32301.  The
public hearing in Orlando is scheduled for Wednesday, February 17, 2010
and will be held from 1:00 p.m. to 5:00 p.m. and 7:00 p.m. to 10:00 p.m.
at the Crowne Plaza Orlando Universal, 7800 Universal Boulevard,
Orlando, FL 32819.  The public hearing in West Palm Beach is scheduled
for Thursday, February 18, 2010 and will be held 1:00 p.m. to 5:00 p.m.
and 7:00 p.m. to 10:00 p.m. at the Holiday Inn Palm Beach Airport, 1301
Belvedere Road, West Palm Beach, FL 33405.  If you need a sign language
interpreter at any of these hearings, you should contact Sharon Frey at
202-566-1480 or   HYPERLINK "mailto:frey.sharon@epa.gov" 
frey.sharon@epa.gov  at least ten business days prior to the meetings so
that appropriate arrangements can be made.  For further information,
including registration information, please refer to the following Web
site:  http://www.epa.gov/waterscience/standards/rules/florida/

FOR FURTHER INFORMATION CONTACT: Danielle Salvaterra, U.S. EPA
Headquarters, Office of Water, Mailcode: 4305T, 1200 Pennsylvania
Avenue, NW, Washington, DC 20460; telephone number: 202-564-1649; fax
number: 202-566-9981; email address: salvaterra.danielle@epa.gov.

SUPPLEMENTARY INFORMATION:  This supplementary information section is
organized as follows: 

Table of Contents  

General Information

Executive Summary

What Entities May Be Affected By This Rule?

What Should I Consider as I Prepare My Comments for EPA?

How Can I Get Copies of This Document and Other Related Information?

Background

Nutrient Pollution

Statutory and Regulatory Background

Water Quality Criteria

Agency Determination Regarding Florida

Proposed Numeric Nutrient Criteria for the State of Florida’s Lakes
and Flowing Waters 

General Information

Proposed Numeric Nutrient Criteria for the State of Florida’s Lakes 

Proposed Numeric Nutrient Criteria for the State of Florida’s Rivers
and Streams

Proposed Numeric Nutrient Criteria for the State of Florida’s Springs
and Clear Streams

Proposed Numeric Nutrient Criteria for South Florida Canals

Comparison Between EPA’s and Florida DEP’s Proposed Numeric Nutrient
Criteria for Florida’s Lakes and Flowing Waters

Applicability of Criteria When Final

Under What Conditions Will Federal Standards Be Either Not Finalized or
Withdrawn?

Alternative Regulatory Approaches and Implementation Mechanisms

Designating Uses

Variances

Site-specific Criteria

Compliance Schedules

Proposed Restoration Water Quality Standards (WQS) Provision

Statutory and Executive Order Reviews

Executive Order 12866:  Regulatory Planning and Review

Paperwork Reduction Act

Regulatory Flexibility Act

Unfunded Mandates Reform Act

Executive Order 13132 (Federalism)

Executive Order 13175 (Consultation and Coordination with Indian Tribal
Governments)

Executive Order 13045 (Protection of Children From Environmental Health
and Safety Risks)

Executive Order 13211 (Actions That Significantly Affect Energy Supply,
Distribution, or Use)

National Technology Transfer Advancement Act of 1995

Executive Order 12898 (Federal Actions To Address Environmental Justice
in Minority Populations and Low-Income Populations)

I. General Information

A. Executive Summary

Excess loadings of nitrogen and phosphorus, commonly referred to as
nutrient pollution, are one of the most prevalent causes of water
quality impairment in the United States.  Anthropogenic nitrogen and
phosphorus over-enrichment in many of the Nation's waters is a
widespread, persistent, and growing problem.  Nutrient pollution can
significantly impact aquatic life and long-term ecosystem health,
diversity, and balance.  More specifically, high nitrogen and phosphorus
loadings, or nutrient pollution, result in harmful algal blooms (HABs),
reduced spawning grounds and nursery habitats, fish kills, and
oxygen-starved hypoxic or “dead” zones.  Public health concerns
related to nutrient pollution include impaired drinking water sources,
increased exposure to toxic microbes such as cyanobacteria, and possible
formation of disinfection byproducts in drinking water, some of which
have been associated with serious human illnesses such as bladder
cancer.  Nutrient problems can exhibit themselves locally or much
further downstream leading to degraded lakes, reservoirs, and estuaries,
and to hypoxic zones where fish and aquatic life can no longer survive.

In the State of Florida, nutrient pollution has contributed to severe
water quality degradation.  Based upon waters assessed and reported in
the 2008 Integrated Water Quality Assessment for Florida, approximately
1,000 miles of rivers and streams, 350,000 acres of lakes, and 900
square miles of estuaries are known to be impaired for nutrients by the
State.  The actual number of stream miles, lake acres, and estuarine
square miles of waters impaired for nutrients in Florida may be higher,
as many waters currently are classified as “unassessed.”

The challenge of nutrient pollution has been a top priority for
Florida’s Department of Environmental Protection (FDEP).  Over the
past decade or more, FDEP has spent over 20 million dollars collecting
and analyzing data on the relationship between phosphorus, nitrogen, and
nitrite-nitrate concentrations and the biological health of aquatic
systems.  Moreover, Florida is one of the few states that has in place a
comprehensive framework of accountability that applies to both point and
nonpoint sources and provides the enforceable authority to address
nutrient reductions in impaired waters based upon the establishment of
site-specific total maximum daily loads (TMDLs).  

Despite FDEP's intensive efforts to diagnose and control nutrient
pollution, substantial water quality degradation from nutrient
over-enrichment remains a significant problem.   On January 14, 2009,
EPA determined under CWA section 303(c)(4)(B) that new or revised WQS in
the form of numeric nutrient water quality criteria are necessary to
meet the requirements of the CWA in the State of Florida.  The Agency
considered 1) the State's documented unique and threatened ecosystems,
2) the high number of impaired waters due to existing nutrient
pollution, and 3) the challenge associated with growing nutrient
pollution resulting from expanding urbanization, continued agricultural
development, and a significantly increasing population that is expected
to grow 75% between 2000 to 2030.  EPA also reviewed the State's
regulatory nutrient accountability system, which represents an
impressive synthesis of technology-based standards, point source control
authority, and authority to establish enforceable controls for nonpoint
source activities.  However, the significant challenge faced by the
water quality components of this system is its dependence upon an
approach involving resource-intensive and time-consuming site-specific
data collection and analysis to interpret non-numeric narrative nutrient
criteria.  EPA determined that Florida’s reliance on a case-by-case
interpretation of its narrative nutrient criterion in implementing an
otherwise comprehensive water quality framework of enforceable
accountability was insufficient to ensure protection of applicable
designated uses.  As part of the Agency’s determination, EPA indicated
that it expected to propose numeric nutrient criteria for lakes and
flowing waters within 12 months, and for estuaries and coastal waters
within 24 months, of the January 14, 2009 determination.

On August 19, 2009, EPA entered into a phased Consent Decree with
Florida Wildlife Federation, Sierra Club, Conservancy of Southwest
Florida, Environmental Confederation of Southwest Florida, and St. Johns
Riverkeeper, committing to sign a proposed rule setting forth numeric
nutrient criteria for lakes and flowing waters in Florida by January 14,
2010, and for Florida's estuarine and coastal waters by January 14,
2011, unless Florida submits and EPA approves State numeric nutrient
criteria before EPA’s proposal.  The phased Consent Decree also
provides that EPA issue a final rule by October 15, 2010 for lakes and
flowing water, and by October 15, 2011 for estuarine and coastal waters,
unless Florida submits and EPA approves State numeric nutrient criteria
before a final EPA action.

Accordingly, this proposal is part of a phased rulemaking process in
which EPA will propose and take final action in 2010 on numeric nutrient
criteria for lakes and flowing waters and for estuaries and coastal
waters in 2011.  The two phases of this rulemaking are linked because
nutrient pollution in Florida's rivers and streams affects not only
instream aquatic conditions but also downstream estuarine and coastal
waters ecosystem conditions.  The Agency could have waited to propose
estuarine and coastal downstream protection criteria values for rivers
and streams as part of the second phase of this rulemaking process. 
However, the substantial data, peer-reviewed methodologies, and
extensive scientific analyses available to and conducted by the Agency
to date indicate that numeric nutrient water quality criteria for
estuaries and coastal waters, when proposed and finalized in 2011, may
result in the need for more stringent rivers and streams criteria to
ensure protection of downstream water quality, particularly for the
nitrogen component of nutrient pollution.  Therefore, considering the
numerous requests for the Agency to share its analysis and scientific
and technical conclusions at the earliest possible opportunity to allow
for full review and comment, EPA is including downstream protection
values for total nitrogen (TN) as proposed criteria for rivers and
streams to protect the State's estuaries and coastal waters in this
notice.  

As described in more detail below and in the technical support document
accompanying this notice, these proposed nitrogen downstream protection
values are based on substantial data, thorough scientific analysis, and
extensive technical evaluation.  However, EPA recognizes that additional
data and analysis may be available, including data for particular
estuaries, to help inform what numeric nutrient criteria are necessary
to protect Florida’s waters, including downstream lakes and estuaries.
 EPA also recognizes that substantial site-specific work has been
completed for a number of these estuaries.  This notice and the proposed
downstream protection values are not intended to address or be
interpreted as calling into question the utility and protectiveness of
these site-specific analyses.  Rather, the proposed values represent the
output of a systematic and scientific approach that was developed to be
generally applicable to all flowing waters in Florida that terminate in
estuaries for the purpose of ensuring the protection of downstream
estuaries. EPA is interested in obtaining feedback at this time on this
systematic and scientific approach.  EPA is also interested in feedback
regarding site-specific analyses for particular estuaries that should be
used instead of this general approach for establishing final values. 
The Agency further recognizes that the proposed values in this notice
will need to be considered in the context of the Agency's numeric
nutrient criteria for estuaries and coastal waters scheduled for
proposal in January of 2011.  

Regarding the criteria for flowing waters for protection of downstream
lakes and estuaries, at this time, EPA intends to take final action on
the criteria for protection of downstream lakes as part of the first
phase of this rulemaking (by October 15, 2010) and to finalize
downstream protection values in flowing waters as part of the second
phase of this rulemaking process (by October 15, 2011) in coordination
with the proposal and finalization of numeric nutrient criteria for
estuarine and coastal waters in 2011.  However, if comments, data and
analyses submitted as a result of this proposal support finalizing these
values sooner, by October 2010, EPA may choose to proceed in this
manner.  To facilitate this process, EPA requests comments and welcomes
thorough evaluation on the technical and scientific basis of these
proposed downstream protection values, as well as information on
estuaries where site-specific analyses should be used, as part of the
broader comment and evaluation process that this proposal initiates.

In accordance with the terms of EPA’s January 14, 2009 determination
and the Consent Decree, EPA is proposing numeric nutrient criteria for
Florida’s lakes and flowing waters which include the following four
water body types:  lakes, streams, springs and clear streams, and canals
in south Florida.  In developing this proposal, EPA worked closely with
FDEP staff to review and analyze the State's extensive dataset of
nutrient-related measurements as well as its analysis of
stressor-response relationships and benchmark or modified-reference
conditions.  EPA also conducted further analyses and modeling, in
addition to requesting an independent external peer review of the core
methodologies and approaches that support this proposal. 

For lakes, EPA is proposing a classification scheme using color and
alkalinity based upon substantial data that show that lake color and
alkalinity play an important role in the degree to which TN and total
phosphorus (TP) concentrations result in a biological response such as
elevated chlorophyll a levels.  EPA found that correlations between
nutrients and biological response parameters in the different types of
lakes in Florida were sufficiently robust, combined with additional
lines of evidence, to support stressor-response criteria development for
Florida’s lakes.  The Agency is also proposing an accompanying
supplementary analytical approach that the State can use to adjust TN
and TP criteria for a particular lake within a certain range where
sufficient data on long-term ambient TN and TP levels are available to
demonstrate that protective chlorophyll a criteria for a specific lake
will still be maintained and attainment of the designated use will be
assured.   This information is presented in more detail in Section III.B
below.  

Regarding numeric nutrient criteria for streams and rivers, EPA
considered the extensive work of FDEP to analyze the relationship
between TN and TP levels and biological response in streams and rivers. 
EPA found that relationships between nutrients and biological response
parameters in rivers and streams were affected by many factors that made
derivation of a quantitative relationship between chlorophyll a levels
and nutrients in streams and rivers difficult to establish in the same
manner as EPA did for lakes (i.e., stressor-response relationship).  EPA
considered an alternative methodology that evaluated a combination of
biological information and data on the distribution of nutrients in a
substantial number of healthy stream systems.  Based upon a technical
evaluation of the significant available data on Florida streams and
related scientific analysis, the Agency concluded that reliance on a
statistical distribution methodology was a stronger and a more sound
approach for deriving TN and TP criteria in streams and rivers.  This
information is presented in more detail in Section III.C below.  

In developing these proposed numeric nutrient criteria for rivers and
streams, EPA also evaluated their effectiveness for assuring the
protection of downstream lake and estuary designated uses pursuant to
the provisions of 40 CFR 130.10(b), which requires that WQS must provide
for the attainment and maintenance of the WQS of downstream waters.  For
rivers and streams in Florida, EPA must ensure, to the extent that
available science allows, that its nutrient criteria take into account
the impact of near-field nutrient loads on aquatic life in downstream
lakes and estuaries.  EPA currently has evaluated the protectiveness of
its rivers and streams TP criteria for lake protection and also the
protectiveness of its rivers and streams TN criteria for 16 out of 26 of
Florida’s downstream estuaries using scientifically sound approaches
for both estimating protective loads and deriving concentration-based
upstream values.  Of the ten downstream estuaries not completely
evaluated to date, seven are in south Florida and receive TN loads from
highly managed canals and waterways and three are in low lying areas of
central Florida. 

As noted above, EPA used best available science and data related to
downstream waters and found that there are cases where the nutrient
criteria EPA is proposing to protect instream aquatic life may not be
stringent enough to ensure protection of aquatic life in certain
downstream lakes and estuaries.  Accordingly, EPA is also proposing an
equation that would be used to adjust stream and river TP criteria to
protect downstream lakes and a different methodology to adjust TN
criteria for streams and rivers to ensure protection of downstream
estuaries.  These approaches as reflected in these proposed regulations
and the revised criteria that would result from adjusting TN criteria
for streams and rivers to ensure protection of downstream estuaries,
based on certain assumptions, are detailed in Section III.C(6)(b) below.
 The Agency specifically requests comment on the available information,
analysis, and modeling used to support the approaches EPA is proposing
for addressing downstream impacts of TN and TP.  EPA also invites
additional stakeholder comment, data, and analysis on alternative
technically-based approaches that would support the development of
numeric nutrient WQS, or some other scientifically defensible approach,
for protection of downstream waters.   To the degree that substantial
data and analyses are submitted that support a significant revision to
downstream protection values for TN outlined in Section III.C(6)(b)
below, EPA would intend to issue a supplemental Federal Register Notice
of Data Availability (NODA) to present the additional data and
supplemental analyses and solicit further comment and input.  EPA
anticipates obtaining the necessary data and information to compute
downstream protection values for TP loads for many estuarine water
bodies in Florida in 2010 and will also make this additional information
available by issuing a supplemental Federal Register NODA.

Regarding numeric nutrient criteria for springs and clear streams, EPA
is proposing a nitrate-nitrite criterion for springs and clear streams
based on experimental laboratory data and field evaluations that
document the response of nuisance algae and periphyton to
nitrate-nitrite concentrations.  This criterion is explained in more
detail in Section III.D below.

For canals in south Florida, EPA is proposing a statistical distribution
approach similar to its approach for rivers and streams, and based on
sites meeting designated uses with respect to nutrients identified in
four canal regions to best represent the necessary criteria to protect
these highly managed water bodies.  This approach is presented in more
detail in Section III.E below.  The Agency has also considered several
alternative approaches to developing numeric nutrient criteria for
canals and these are described, as well, for public comment and
response. 

Stakeholders have expressed concerns that numeric nutrient criteria must
be scientifically sound.  Under the Clean Water Act and EPA's
implementing regulations, numeric nutrient standards must protect the
designated use of a water (as well as ensure protection of downstream
uses) and must be based on sound scientific rationale.  In the case of
Florida, EPA and FDEP scientists completed a substantial body of
scientific work; EPA believes that these proposed criteria clearly meet
the regulatory standards of protection and that they are clearly based
on a sound scientific rationale.

Separate from and in addition to proposing numeric nutrient criteria,
EPA is also proposing a new WQS regulatory tool for Florida, referred to
as “restoration WQS” for impaired waters.  This tool will enable
Florida to set incremental water quality targets (uses and criteria) for
specific pollutant parameters while at the same time retaining
protective criteria for all other parameters to meet the full aquatic
life use.  The goal is to provide a challenging but realistic
incremental framework in which to establish appropriate control
measures.  This provision will allow Florida to retain full aquatic life
protection (uses and criteria) for its water bodies while establishing a
transparent phased WQS process that would result in planned
implementation of enforceable measures and requirements to improve water
quality over a specified time period to ultimately meet the long-term
designated aquatic life use.  The phased numeric standards would be
included in Florida’s water quality regulations during the restoration
period.  This proposed regulatory tool is discussed in more detail in
Section VI below.

Finally, EPA is including in this notice a proposed approach for
deriving Federal site-specific alternative criteria (SSAC) based upon
State submissions of scientifically defensible recalculations that meet
the requirements of CWA section 303(c).  TMDL targets submitted to EPA
by the State for consideration as new or revised WQS could be reviewed
under this SSAC process.  This proposed approach is discussed in more
detail in Section V.C below.

Overall, EPA is soliciting comments and data regarding EPA’s proposed
criteria for lakes and flowing waters, the derivation of these criteria,
the protectiveness of the streams and rivers criteria for downstream
waters, and all associated alternative options and methodologies
discussed in this proposed rulemaking.

B. What Entities May Be Affected By This Rule?

Citizens concerned with water quality in Florida may be interested in
this rulemaking.  Entities discharging nitrogen or phosphorus to lakes
and flowing waters of Florida could be indirectly affected by this
rulemaking because WQS are used in determining National Pollutant
Discharge Elimination System (“NPDES”) permit limits.  Stakeholders
in Florida facing obstacles in immediately achieving full aquatic life
protection in impaired waters may be interested in the restoration
standards concept outlined in this rulemaking.  Categories and entities
that may ultimately be affected include:

Category	Examples of potentially affected entities

Industry	Industries discharging pollutants to lakes and flowing waters
in the State of Florida.

Municipalities

	Publicly-owned treatment works discharging pollutants to lakes and
flowing waters in the State of Florida.

Stormwater Management Districts 	Entities responsible for managing
stormwater runoff in Florida.



	This table is not intended to be exhaustive, but rather provides a
guide for entities that may be directly or indirectly affected by this
action.  This table lists the types of entities of which EPA is now
aware that potentially could be affected by this action.  Other types of
entities not listed in the table could also be affected, such as
nonpoint source contributors to nutrient pollution in Florida’s
waters.  Any parties or entities conducting activities within watersheds
of the Florida waters covered by this rule, or who rely on, depend upon,
influence, or contribute to the water quality of the lakes and flowing
waters of Florida, might be affected by this rule.  To determine whether
your facility or activities may be affected by this action, you should
examine this proposed rule.  If you have questions regarding the
applicability of this action to a particular entity, consult the person
listed in the preceding FOR FURTHER INFORMATION CONTACT section.

C. What Should I Consider as I Prepare My Comments for EPA?

    1. Submitting CBI. Do not submit this information to EPA through  
HYPERLINK "http://www.regulations.gov"  http://www.regulations.gov  or
e-mail.  Clearly mark the part or all of the information that you claim
to be CBI.  For CBI information in a disk or CD-ROM that you mail to
EPA, mark the outside of the disk or CD-ROM as CBI and then identify
electronically within the disk or CD-ROM the specific information that
is claimed as CBI.  In addition to one complete version of the comment
that includes information claimed as CBI, a copy of the comment that
does not contain the information claimed as CBI must be submitted for
inclusion in the public docket.  Information so marked will not be
disclosed except in accordance with procedures set forth in 40 CFR part
2.

    2. Tips for Preparing Your Comments. When submitting comments,
remember to:

Identify the rulemaking by docket number and other identifying
information (subject heading, Federal Register date, and page number).

Follow directions--The agency may ask you to respond to specific
questions or organize comments by referencing a Code of Federal
Regulations (CFR) part or section number.

Explain why you agree or disagree; suggest alternatives and substitute
language for your requested changes.

Describe any assumptions and provide any technical information and/or
data that you used.

If you estimate potential costs or burdens, explain how you arrived at
your estimate in sufficient detail to allow for it to be reproduced.

Provide specific examples to illustrate your concerns, and suggest
alternatives.

Make sure to submit your comments by the comment period deadline
identified.

D. How Can I Get Copies of This Document and Other Related Information?

    1. Docket. EPA has established an official public docket for this
action under Docket Id. No. EPA-HQ-OW-2009-0596.  The official public
docket consists of the document specifically referenced in this action,
any public comments received, and other information related to this
action.  Although a part of the official docket, the public docket does
not include CBI or other information whose disclosure is restricted by
statute.  The official public docket is the collection of materials that
is available for public viewing at the OW Docket, EPA West, Room 3334,
1301 Constitution Ave., NW, Washington, DC 20004.  This Docket Facility
is open from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding
legal holidays.  The Docket telephone number is 202-566-1744.  A
reasonable fee will be charged for copies.

    2. Electronic Access. You may access this Federal Register document
electronically through the EPA Internet under the “Federal Register”
listings at   HYPERLINK "http://www.epa.gov/fedrgstr/" 
http://www.epa.gov/fedrgstr/ .  

	An electronic version of the public docket is available through EPA's
electronic public docket and comment system, EPA Dockets.  You may use
EPA Dockets at   HYPERLINK "http://www.regulations.gov" 
http://www.regulations.gov  to view public comments, access the index
listing of the contents of the official public docket, and to access
those documents in the public docket that are available electronically. 
For additional information about EPA's public docket, visit the EPA
Docket Center homepage at   HYPERLINK
"http://www.epa.gov/epahome/dockets.htm" 
http://www.epa.gov/epahome/dockets.htm .  Although not all docket
materials may be available electronically, you may still access any of
the publicly available docket materials through the Docket Facility
identified in Section I.D(1).

II. Background

A. Nutrient Pollution 

1. What is Nutrient Pollution?

	Excess anthropogenic concentrations of nitrogen (typically in oxidized,
inorganic forms, such as nitrate) and phosphorus (typically as
phosphate), commonly referred to as nutrient pollution, in surface
waters can result in excessive algal and aquatic plant growth, referred
to as eutrophication.  One impact associated with eutrophication is low
dissolved oxygen, due to decomposition of the aquatic plants and algae
when these plants and algae die.  As noted above, high nitrogen and
phosphorus loadings also result in HABs, reduced spawning grounds and
nursery habitats for aquatic life, and fish kills.  Public health
concerns related to eutrophication include impaired drinking water
sources, increased exposure to toxic microbes such as cyanobacteria, and
possible formation of disinfection byproducts in drinking water, some of
which have been associated with serious human illnesses such as bladder
cancer.,   Nutrient problems can manifest locally or much further
downstream in lakes, reservoirs, and estuaries.  

	Excess nutrients in water bodies come from many sources, which can be
grouped into five major categories:  1) sources associated with urban
land use and development, 2) municipal and industrial waste water
discharge, 3) row crop agriculture, 4) animal husbandry, and 5)
atmospheric deposition that may be increased by production of nitrogen
oxides in electric power generation and internal combustion engines. 
These sources contribute significant loadings of nitrogen and phosphorus
to surface waters causing major impacts to aquatic ecosystems and
significant imbalances in the natural populations of flora and fauna.   


2. Adverse Impacts of Nutrient Pollution on Aquatic Life, Human Health,
and the Economy

To protect aquatic life, EPA regulates pollutants that have adverse
effects on aquatic life.  For most pollutants, these effects are
typically negative impacts on growth, reproduction, and survival.  As
previously noted, excess nutrients can lead to increases in algal and
other aquatic plant growth, including toxic algae that can result in
HABs.  Increases in algal and aquatic plant growth provide excess
organic matter in a water body and can contribute to subsequent
degradation of aquatic communities, human health impacts, and ultimately
economic impacts.

Fish, shellfish, and wildlife require clean water for survival.  Changes
in the environment resulting from elevated nutrient levels (such as
algal blooms, toxins from HABs, and hypoxia/anoxia) can cause a variety
of effects.  When excessive nutrient loads change a water body’s algae
and plant species, the change in habitat and available food resources
can induce changes affecting an entire food chain.  Algal blooms block
sunlight that submerged grasses need to grow, leading to a decline of
seagrass beds and decreased habitat for juvenile organisms.  Algal
blooms can also increase turbidity and impair the ability of fish and
other aquatic life to find food.  Algae can also damage or clog the
gills of fish and invertebrates.

HABs can form toxins that cause illness or death for some animals.  Some
of the more commonly affected animals include sea lions, turtles,
seabirds, dolphins, and manatees.  More than 50% of unusual marine
mortality events may be associated with HABs.  Lower level consumers,
such as small fish or shellfish, may not be harmed by algal toxins, but
they bioaccumulate toxins, causing higher exposures for higher level
consumers (such as larger predator fish), resulting in health
impairments and possibly death., 

There are many examples of HAB toxins significantly affecting marine
animals. For example, between March and April 2003, 107 bottlenose
dolphins (Tursiops truncatus) died, along with hundreds of fish and
marine invertebrates, along the Florida Panhandle.  High levels of
brevetoxin (a neurotoxin), produced by a harmful species of
dinoflagellate (a type of algae), were measured in all of the stranded
dolphins examined, as well as in their fish prey. 

In freshwater, cyanobacteria can produce toxins that have been
implicated as the cause of a large number of fish and bird mortalities. 
These toxins have also been tied to the death of pets and livestock that
may be exposed through drinking contaminated water or grooming
themselves after bodily exposure.  A recent study showed that at least
one type of cyanobacteria has been linked to cancer and tumor growth in
animals.

Excessive algal growth contributes to increased oxygen consumption
associated with decomposition, potentially reducing oxygen to levels
below that needed for aquatic life to survive and flourish.,   Low
oxygen, or hypoxia, often occurs in episodic "events," which sometimes
develop overnight.  Mobile species, such as adult fish, can sometimes
survive by moving to areas with more oxygen.  However, migration to
avoid hypoxia depends on species mobility, availability of suitable
habitat, and adequate environmental cues for migration.  Less mobile or
immobile species, such as oysters and mussels, cannot move to avoid low
oxygen and are often killed during hypoxic events.  While certain mature
aquatic animals can tolerate a range of dissolved oxygen levels that
occur in the water, younger life stages of species like fish and
shellfish often require higher levels of oxygen to survive.  Sustained
low levels of dissolved oxygen cause a severe decrease in the amount of
aquatic life in hypoxic zones and affect the ability of aquatic
organisms to find necessary food and habitat.  In extreme cases, anoxic
conditions occur when there is a complete lack of oxygen.  Very few
organisms can live without oxygen (for example some microbes), hence
these areas are sometimes referred to as dead zones.

Primary impacts to humans result directly from elevated nutrient
pollution levels and indirectly from the subsequent water body changes
that occur from increased nutrients (such as algal blooms and toxins). 
Direct impacts include effects on human health through drinking water or
consuming toxic shellfish.  Indirect impacts include restrictions on
recreation (such as boating, swimming, and kayaking).  Algal blooms can
prevent opportunities to swim and engage in other types of recreation. 
In areas where recreation is determined to be unsafe because of algal
blooms, warning signs are often posted to discourage human use of the
waters.  

onitoring of Florida Public Water Supplies from 2004-2007 indicates that
violations of nitrate maximum contaminant levels (MCL) ranged from 34-40
violations annually.  In addition, in the predominantly agricultural
regions of Florida, of 3,949 drinking water wells analyzed for nitrate
by the Florida Department of Agriculture and Consumer Services, (FDACS)
and the FDEP, 2,483 (63%) contained detectable nitrate and 584 wells
(15%) contained nitrate above the U.S. EPA MCL. Of the 584 wells
statewide that exceeded the MCL, 519 were located in the Central Florida
Ridge citrus growing region, encompassed primarily by Lake, Polk and
Highland Counties.  Human health can also be impacted by disinfection
byproducts formed when disinfectants (such as chlorine) used to treat
drinking water react with organic carbon (from the algae in source
waters).  Some disinfection byproducts have been linked to rectal,
bladder, and colon cancers; reproductive health risks; and liver,
kidney, and central nervous system problems.,  Humans can also be
impacted by accidentally ingesting toxins, resulting from toxic algal
blooms in water, while recreating or by consuming drinking water that
still contains toxins despite treatment.  For example, cyanobacteria
toxins can sometimes pass through the normal water treatment process. 
After consuming seafood tainted by toxic HABs, humans can develop
gastrointestinal distress, memory loss, disorientation, confusion, and
even coma and death in extreme cases.  Some toxins only require a small
dose to cause illness or death.  EPA expects that by addressing
protection of aquatic life uses through the application of the proposed
numeric nutrient criteria in this rulemaking, risks to human health will
also be alleviated, as nutrient levels that represent a balance of
natural populations of flora and fauna will not produce HABs nor result
in highly elevated nitrate levels. 

Nutrient pollution and eutrophication can also impact the economy
through additional reactive costs, such as medical treatment for humans
who ingest HAB toxins, treating drinking water supplies to remove algae
and organic matter, and monitoring water for shellfish and other
affected resources.  

Economic losses from algal blooms and HABs can include reduced property
values for lakefront areas, commercial fishery losses, and lost revenue
from recreational fishing and boating trips, as well as other
tourism-related businesses.  Commercial fishery losses occur because of
a decline in the amount of fish available for harvest due to habitat and
oxygen declines.  Some HAB toxins can make seafood unsafe for human
consumption, and can reduce the amount of fish bought because people
might question if eating fish is safe after learning of the presence of
the algal bloom.  To put the issue into perspective, consider the
following estimates:  for freshwater lakes, losses in fishing and
boating trip-related revenues nationwide due to eutrophication are
estimated to range from $370 million to almost $1.2 billion dollars and
loss of lake property values from excessive algal growth are estimated
to range from $300 million to $2.8 billion annually on a national level.
 

	3. Nutrient Pollution in Florida

Water quality degradation resulting from excess nitrogen and phosphorus
loadings is a documented and significant environmental issue in Florida.
 According to Florida’s 2008 Integrated Report, approximately 1,000
miles of rivers and streams, 350,000 acres of lakes, and 900 square
miles of estuaries are impaired for nutrients in the State.  To put this
in context, these values represent approximately 5% of the assessed
river and stream miles, 23% of the assessed lake acres, and 24% of the
assessed square miles of estuaries that Florida has listed as impaired
in the 2008 Integrated Report.  Nutrients are ranked as the fourth major
source of impairment for rivers and streams in the State (after
dissolved oxygen, mercury in fish, and fecal coliforms).  For lakes and
estuaries, nutrients are ranked first and second, respectively.  As
discussed above, impairments due to nutrient pollution result in
significant impacts to aquatic life and ecosystem health.  Nutrient
pollution also represents, as mentioned above, an increased human health
risk in terms of contaminated drinking water supplies and private wells.

Florida is particularly vulnerable to nutrient pollution.  Historically,
the State has experienced a rapidly expanding population, which is a
strong predictor of nutrient loading and associated effects, and which
combined with climate and other natural factors, make Florida waters
sensitive to nutrient effects.  Florida is currently the fourth most
populous state in the nation, with an estimated 18 million people. 
Population is expected to continue to grow, resulting in an expected
increase in urban development, home landscapes, and wastewater. 
Florida's flat topography causes water to move slowly over the
landscape, allowing ample opportunity for eutrophication responses to
develop.  Similarly, small tides in many of Florida's estuaries
(especially on the Gulf coast) also allow for well-developed
eutrophication responses in tidal waters.  Florida's warm and wet, yet
sunny, climate further contributes to increased run-off and subsequent
eutrophication responses.  Exchanges of surface water and ground water
contribute to complex relationships between nutrient sources and the
location and timing of eventual impacts. 

In addition, extensive agricultural development and associated
hydrologic modifications (e.g., canals and ditches) amplify the
State’s susceptibility to nutrient pollution.  Many of Florida’s
inland areas have extensive tracts of agricultural lands.  Much of the
intensive agriculture and associated fertilizer usage takes place in
locations dominated by poorly drained sandy soils and with high annual
rainfall amounts, two conditions favoring nutrient-rich runoff.  These
factors, along with population increase, have contributed to a
significant upward trend in nutrient inputs to Florida’s waters.  High
historical water quality and the human and aquatic life uses of many
waterways in Florida often means that very low nutrients, low
productivity, and high water clarity are needed and expected to maintain
uses.

B. Statutory and Regulatory Background  

Section 303(c) (33 U.S.C. 1313(c)) of the CWA directs states to adopt
WQS for their navigable waters.  Section 303(c)(2)(A) and EPA's
implementing regulations at 40 CFR part 131 require, among other
provisions, that state WQS include the designated use or uses to be made
of the waters and criteria that protect those uses.  EPA regulations at
40 CFR 131.11(a)(1) provide that states shall "adopt those water quality
criteria that protect the designated use" and that such criteria "must
be based on sound scientific rationale and must contain sufficient
parameters or constituents to protect the designated use."  As noted
above, 40 CFR 130.10(b) provides that "In designating uses of a water
body and the appropriate criteria for those uses, the state shall take
into consideration the water quality standards of downstream waters and
ensure that its water quality standards provide for the attainment and
maintenance of the water quality standards of downstream waters.”

States are also required to review their WQS at least once every three
years and, if appropriate, revise or adopt new standards (CWA section
303(c)(1)).  States are required to submit these new or revised WQS for
EPA review and approval or disapproval (CWA section 303(c)(2)(A)). 
Finally, CWA section 303(c)(4)(B) authorizes the Administrator to
determine, even in the absence of a state submission, that a new or
revised standard is needed to meet CWA requirements.  The criteria
proposed in this rulemaking apply to lakes and flowing waters of the
State of Florida.  EPA’s proposal defines “lakes and flowing
waters” to mean inland surface waters that have been classified as by
Florida as Class I (Potable Water Supplies Use) or Class III
(Recreation, Propagation and Maintenance of a Healthy, Well-Balanced
Population of Fish and Wildlife Use) water bodies pursuant to Florida
Administrative Code (F.A.C.) Rule 62-302.400, excluding wetlands, and
which are predominantly fresh waters.  

C. Water Quality Criteria 

EPA has issued guidance for use by states when developing criteria. 
Under CWA section 304(a), EPA periodically publishes criteria
recommendations (guidance) for use by states in setting water quality
criteria for particular parameters to protect recreational and aquatic
life uses of waters.  When EPA has published recommended criteria,
states have the option of adopting water quality criteria based on
EPA’s CWA section 304(a) criteria guidance, section 304(a) criteria
guidance modified to reflect site-specific conditions, or other
scientifically defensible methods.  40 CFR 131.11(b)(1).  

	For nutrients, EPA has published under CWA section 304(a) a series of
peer-reviewed, national technical approaches and methods regarding the
development of numeric nutrient criteria for lakes and reservoirs,
rivers and streams, and estuaries and coastal marine waters.  Basic
analytical approaches for nutrient criteria derivation include, but are
not limited to: 1) stressor-response analysis, 2) the reference
condition approach, and 3) mechanistic modeling.  The stressor-response,
or effects-based, approach relates a water body’s response to
nutrients and identifies adverse effect levels.  This is done by
selecting a protective value based on the relationships of nitrogen and
phosphorus field measures with indicators of biological response.  This
approach is empirical, and directly relates to the designated uses.  The
reference condition approach derives candidate criteria from
distributions of nutrient concentrations and biological responses in a
group of waters.  Measurements are made of causal and response variables
and a protective value is selected from the distribution.  The
mechanistic modeling approach predicts a cause-effect relationship using
site-specific input to equations that represent ecological processes. 
Mechanistic models require calibration and validation.  Each approach
has peer review support by the broader scientific community, and would
provide adequate means for any state to develop scientifically
defensible numeric nutrient criteria.

	In cases where scientifically defensible numeric criteria cannot be
derived, EPA regulations provide that narrative criteria should be
adopted.  40 CFR 131.11(b)(2).  Narrative criteria are descriptions of
conditions necessary for the water body to attain its designated use. 
Often expressed as requirements that waters remain “free from”
certain characteristics, narrative criteria can be the basis for
controlling nuisance conditions such as floating debris or objectionable
deposits.  States often establish narrative criteria, such as "no toxics
in toxic amounts," in order to limit toxic pollutants in waters where
the state has yet to adopt an EPA-recommended numeric criterion and or
where EPA has yet to derive a recommended numeric criterion.  For
nutrients, in the absence of numeric nutrient criteria, states have
often established narrative criteria such as "no nuisance algae." 
Reliance on a narrative criterion to derive NPDES permit limits, assess
water bodies for listing purposes, and establish TMDL targets can often
be a difficult, resource-intensive, and time-consuming process that
entails conducting case-by-case analyses to determine the appropriate
numeric target value based on a site-specific translation of the
narrative criterion.  Narrative criteria are most effective when they
are supported by procedures to translate them into quantitative
expressions of the conditions necessary to protect the designated use.  

D. Agency Determination Regarding Florida

On January 14, 2009, EPA determined under CWA section 303(c)(4)(B) that
new or revised WQS in the form of numeric nutrient water quality
criteria are necessary to meet the requirements of the CWA in the State
of Florida.  Florida’s currently applicable narrative nutrient
criterion provides, in part, that “in no case shall nutrient
concentrations of a body of water be altered so as to cause an imbalance
in natural populations of aquatic flora or fauna.” Florida
Administrative Code (F.A.C.) 62-302-530(47)(b).  EPA determined that
Florida’s narrative nutrient criterion alone was insufficient to
ensure protection of applicable designated uses.  The determination
recognized that Florida has a proactive and innovative program to
address nutrient pollution through a strategy of  comprehensive National
Pollutant Discharge Elimination System  (NPDES) permit regulations,
Basin Management Action Plans (BMAPs) for implementation of TMDLs which
include controls on nonpoint sources, municipal wastewater treatment
technology-based requirements under the 1990 Grizzle-Figg Act, and 
rules to limit nutrient pollution in geographically specific areas like
the Indian River Lagoon System, the Everglades Protection Area, and
Wekiva Springs.  However, the determination noted that despite
Florida’s intensive efforts to diagnose and control nutrient
pollution, substantial water quality degradation from nutrient
over-enrichment remains a significant challenge in the State and one
that is likely to worsen with continued population growth and land-use
changes. 

Florida’s implementation of its narrative water quality criterion for
nutrients is based on site-specific detailed biological assessments and
analyses, together with site-by-site outreach and stakeholder engagement
in the context of specific CWA-related actions, specifically NPDES
permits, TMDLs required for both permitting and BMAP activities, and
assessment and listing decisions.  When deriving NPDES water
quality-based permit limits, Florida initially conducts a site-specific
analysis to determine whether a proposed discharge has the reasonable
potential to cause or contribute to an exceedance of its narrative
nutrient water quality criterion.  The State then determines what levels
of nutrients would “cause an imbalance in natural populations of
aquatic flora or fauna” and translates those levels into numeric
“targets” for the receiving water and any other affected waters. 
Determining on a water-by-water basis for thousands of State waters the
levels of nutrients that would “cause an imbalance in natural
populations of aquatic flora or fauna” is a difficult, lengthy, and
data-intensive undertaking.  This work involves performing detailed
site-specific analyses of the receiving water and any other affected
waters.  If the State has not already completed this analysis for a
particular water, it can be very difficult to accurately determine in
the context and timeframe of the NPDES permitting process.  For example,
in some cases, adequate data may take several years to collect and
therefore, may not be available for a particular water at the time of
permitting issuance or re-issuance.

When developing TMDLs, as it does when determining reasonable potential
and deriving limits in the permitting context, Florida translates the
narrative nutrient criterion into a numeric target that the State
determines is necessary to meet its narrative criterion and protect
applicable designated uses. This process also involves a site-specific
analysis to determine the nutrient levels that would “cause an
imbalance in natural populations of aquatic flora or fauna” in a
particular water.  Each time a site-specific analysis is conducted to
determine what the narrative criterion means for a particular water body
in developing a TMDL, the State takes site-specific considerations into
account and devises a method that works with the available data and
information. 

In adopting the Impaired Waters Rule (IWR), Florida took important steps
toward improving implementation of its narrative nutrient criterion by
establishing and publishing an assessment methodology to identify waters
impaired for nutrients.  This methodology includes numeric nutrient
impairment “thresholds” above which waters are automatically deemed
impaired.  Even when a listing is made, however, development of a TMDL
is then generally required to support issuance of a permit or
development of a BMAP. 

Based on the considerations outlined above, EPA concluded that numeric
criteria for nutrients will enable the State to take necessary actions
to protect the designated uses, in a timelier manner.  The resource
intensive efforts to interpret the State’s narrative criterion
contribute to delays in implementing the criterion and therefore, affect
the State’s ability to provide the needed protections for applicable
designated uses.  EPA, therefore, determined that numeric nutrient
criteria are necessary for the State of Florida to meet the CWA
requirement to have criteria that protect applicable designated uses.  

The combined impacts of urban and agricultural activities, along with
Florida’s physical features and important and unique aquatic
ecosystems, made it clear that the current use of the narrative nutrient
criterion alone and the resulting delays that it entails do not ensure
protection of applicable designated uses for the many State waters that
are either unimpaired and need protection or have been listed as
impaired and require loadings reductions.  EPA determined that numeric
nutrient water quality criteria would strengthen the foundation for
identifying impaired waters, establishing TMDLs, and deriving water
quality-based effluent limits in NPDES permits, thus providing the
necessary protection for the State’s designated uses in its waters. 
In addition, numeric nutrient criteria will support the State’s
ability to effectively partner with point and nonpoint sources to
control nutrients, thus further providing the necessary protection for
the designated uses of the State’s water bodies.  EPA’s
determination is available at the following Web site:    HYPERLINK
"http://www.epa.gov/waterscience/standards/rules/fl-determination.htm" 
http://www.epa.gov/waterscience/standards/rules/fl-determination.htm 

The January 14, 2009 determination stated EPA’s intent to propose
numeric nutrient criteria for lakes and flowing waters in Florida within
twelve months of the January 14, 2009 determination, and for estuarine
and coastal waters within 24 months of the determination.  EPA has also
entered into a Consent Decree with Florida Wildlife Federation, Sierra
Club, Conservancy of Southwest Florida, Environmental Confederation of
Southwest Florida, and St. Johns Riverkeeper, committing to the schedule
stated in EPA’s January 14, 2009 determination to propose numeric
nutrient criteria for lakes and flowing waters in Florida by January 14,
2010, and for Florida's estuarine and coastal waters by January 14,
2011.  The Consent Decree also requires that final rules be issued by
October 15, 2010 for lakes and flowing waters, and by October 15, 2011
for estuarine and coastal waters.  

In accordance with the determination and EPA’s Consent Decree, EPA is
proposing numeric nutrient criteria for Florida’s lakes and flowing
waters with this proposed rule.  As envisioned in EPA’s determination,
this time frame has allowed EPA to utilize the large data set collected
by Florida as part of a detailed analysis of nutrient-impaired waters. 
In a separate rulemaking, EPA intends to develop and propose numeric
nutrient criteria for Florida’s estuarine and coastal waters by
January 14, 2011.  EPA’s determination did not apply to Florida’s
wetlands, and as a result, Florida’s wetlands will not be addressed in
this rulemaking or in EPA’s forthcoming rulemaking involving estuaries
and coastal waters.  

III. Proposed Numeric Nutrient Criteria for the State of Florida’s
Lakes and Flowing Waters

A.  General Information

(1)  Which Water Bodies Are Affected By This Proposed Rule? 

The criteria proposed in this rulemaking apply to lakes and flowing
waters of the State of Florida.  EPA’s proposal defines “lakes and
flowing waters” to mean inland surface waters that have been
classified as Class I (Potable Water Supplies) or Class III (Recreation,
Propagation and Maintenance of a Healthy, Well-Balanced Population of
Fish and Wildlife) water bodies pursuant to Rule 62-302.400, F.A.C.,
excluding wetlands, and which are predominantly fresh waters.  Pursuant
to Rule 62-302.200, F.A.C., EPA’s proposal defines “predominantly
fresh waters” to mean surface waters in which the chloride
concentration at the surface is less than 1,500 milligrams per liter
(mg/L) and “surface water” means water upon the surface of the
Earth, whether contained in bounds created naturally, artificially, or
diffused.  Waters from natural springs shall be classified as surface
water when it exits from the spring onto the Earth’s surface.

In this rulemaking, EPA is proposing numeric nutrient criteria for the
following four water body types:  lakes, streams, springs and clear
streams, and canals in south Florida.  EPA’s proposal also includes
definitions for each of these waters.  “Lake” means a freshwater
water body that is not a stream or other watercourse with some open
contiguous water free from emergent vegetation.  “Stream” means a
free-flowing, predominantly fresh surface water in a defined channel,
and includes rivers, creeks, branches, canals (outside south Florida),
freshwater sloughs, and other similar water bodies.  “Spring” means
the point where underground water emerges onto the Earth’s surface,
including its spring run.  “Spring run” means a free-flowing water
that originates from a spring or spring group whose primary (>50%)
source of water is from a spring or spring group.  Downstream waters
from a spring that receive 50% or more of their flow from surface water
tributaries are not considered spring runs.  “Clear stream” means a
free-flowing water whose color is less than 40 platinum cobalt units
(PCU, which is assessed as true color free from turbidity). 
Classification of a stream as clear or colored is based on the
instantaneous color of the sample.  Consistent with Rule 62-312.020,
F.A.C., “canal” means a trench, the bottom of which is normally
covered by water with the upper edges of its two sides normally above
water.  Consistent with Rule 62-302.200, F.A.C., all secondary and
tertiary canals wholly within Florida’s agricultural areas are
classified as Class IV waters, not Class III, and therefore, are not
subject to this proposed rulemaking.  The classes of waters, as
specified in this paragraph and as subject to this proposed rulemaking,
are hereinafter referred to as “lakes and flowing waters” in this
proposed rule.

The CWA requires adoption of WQS for “navigable waters.”  CWA
section 303(c)(2)(A).  The CWA defines “navigable waters” to mean
“the waters of the United States, including the territorial seas.” 
CWA section 502(7).  Whether a particular water body is a water of the
United States is a water body-specific determination.  Every water body
that is a water of the United States requires protection under the CWA. 
EPA is not aware of any waters of the United States in Florida that are
currently exempted from the State’s WQS.  For any privately-owned
water in Florida that is a water of the United States, the applicable
numeric nutrient criteria for those types of waters would apply.  This
rule does not apply to waters for which the Miccosukee Tribe of Indians
or Seminole Tribe of Indians has obtained Treatment as a State for
Section 303 of the CWA, pursuant to Section 518 of the CWA.

(2) Background on EPA’s Derivation of Proposed Numeric Nutrient
Criteria for the State of Florida’s Lakes and Flowing Waters 

	 In proposing numeric nutrient criteria for Florida's lakes and flowing
waters, EPA developed numeric nutrient criteria to support a balanced
natural population of flora and fauna in Florida lakes and flowing
waters, and to ensure, to the extent that the best available science
allows, the attainment and maintenance of the WQS of downstream waters. 
Where numeric nutrient criteria do not yet exist, in proposed or final
form, for a water body type that is downstream from a lake or flowing
water (e.g., estuaries) in Florida, EPA has interpreted the currently
applicable State narrative criterion, "in no case shall nutrient
concentrations of a body of water be altered so as to cause an imbalance
in natural populations of aquatic flora or fauna,” to ensure that the
numeric criteria EPA is proposing would not result in nutrient
concentrations that would "cause an imbalance in natural populations of
aquatic flora or fauna” in such downstream water bodies.  EPA’s
actions are consistent with and support existing Florida WQS
regulations.  EPA used the best available science to estimate protective
loads to downstream estuaries, and then used these estimates (and
assumptions about the distribution of the load throughout the
watershed), along with mathematical models, to calculate concentrations
in upstream flowing waters that would have to be met to ensure the
attainment and maintenance of the State’s narrative criterion
applicable to downstream estuaries.

EPA relied on an extensive amount of Florida-specific data, collected
and analyzed, in large part, by FDEP and then reviewed by EPA.  EPA
worked extensively with FDEP on data interpretation and technical
analyses for developing scientifically sound numeric nutrient criteria
for this proposed rulemaking.  Because EPA is committed to ensuring the
use of the best available science, the Agency submitted its criteria
derivation methodologies, developed by EPA in close collaboration with
FDEP experts and scientists, to an independent, external, scientific
peer review in July 2009.  

To support derivation of EPA’s proposed lakes criteria, EPA searched
extensively for relevant and useable lake data.  In this case the effort
resulted in 33,622 samples from 4,417 sites distributed among 1,599
lakes statewide.  

Regarding the derivation of EPA’s proposed streams criteria, EPA
evaluated water chemistry data from 11,761 samples from 6,342 sites
statewide in the “all streams” dataset.  EPA also used data
collected for linking nutrients to specific biological responses that
consisted of 2,023 sample records from more than 1,100 streams.

For EPA’s proposed springs and clear streams criteria, EPA evaluated
data gathered and synthesized by FDEP using approximately 50 studies
including historical accounts, laboratory nutrient amendment bioassays,
field surveys, and TMDL reports that document increasing patterns of
nitrate-nitrite levels and corresponding ecosystem level responses
observed within the last 50 years.  At least a dozen of these studies
were used to develop and support the proposed nitrate-nitrite criterion
for spring ecosystems.  

For EPA’s proposed criteria for canals for south Florida, EPA started
with more than 1,900,000 observations from more than 3,400 canal sites. 
These were filtered for data relevant to nutrient criteria development
and resulted in observations at more than 500 sites for variables
(nutrient parameter data and chlorophyll a data).  Reliance on these
extensive sets of data has enabled EPA to use the best available
information and science to derive robust, scientifically sound criteria
applicable to Florida’s lakes and flowing waters.

Section III describes EPA’s proposed numeric nutrient criteria for
Florida’s lakes, streams, springs and clear streams, and canals and
the associated methodologies EPA employed to derive them.  These
criteria are based on sound scientific rationale and will protect
applicable designated uses in Florida’s lakes and flowing waters.  EPA
solicits public comment on these criteria and their derivation.  This
preamble also includes discussions of alternative approaches that EPA
considered but did not select as the preferred option to derive the
proposed criteria.  EPA invites public comment on the alternative
approaches as well.  In addition, EPA requests public comment on whether
the proposed numeric nutrient criteria are consistent with Florida’s
narrative criterion with respect to nutrients at Rule 62-302.530(47)(a),
F.A.C., specifying that the discharge of nutrients shall be limited as
needed to prevent violations of other standards.  EPA seeks scientific
data and information on whether, for example, nutrient criteria should
be more stringent to prevent exceedances of dissolved oxygen criteria.

EPA has created a technical support document that provides detailed
information regarding all methodologies discussed herein and the
derivation of the proposed criteria.  This document is entitled
“Technical Support Document for EPA’s Proposed Rule For Numeric
Nutrient Criteria for Florida’s Inland Surface Fresh Waters”
(hereafter, EPA TSD for Florida’s Inland Waters) and is located at  
HYPERLINK "http://www.regulations.gov"  www.regulations.gov , Docket ID
No. EPA-HQ-OW-2009-0596.

B.  Proposed Numeric Nutrient Criteria for the State of Florida’s
Lakes

Florida's 2008 Integrated Water Quality Assessment Report indicates that
Florida lakes provide important habitats for plant and animal species
and are a valuable resource for human activities and enjoyment.  The
State has more than 7,700 lakes, which occupy close to 6% of its surface
area.  The largest lake, Lake Okeechobee (covering 435,840 acres), is
the ninth largest lake in surface area in the United States and the
second largest freshwater lake wholly within the coterminous United
States.  Most of the State’s lakes are shallow, averaging seven to 20
feet deep, although many sinkhole lakes and parts of other lakes are
much deeper. 

Florida’s lakes are physically, chemically, and biologically diverse.
Many lakes are spring-fed, others are seepage lakes fed by ground water,
and still others (about 20%) are depression lakes fed by surface water
sources.  For purposes of developing numeric nutrient criteria, EPA
identified two classifications of lakes, colored lakes and clear lakes,
which respond differently to inputs of TN and TP, as discussed in detail
below.  EPA further classified the clear lakes into clear alkaline lakes
(relatively high alkalinity) and clear acidic lakes (relatively low
alkalinity), which have different baseline expectations for the level of
nutrients present.

(1)  Proposed Numeric Nutrient Criteria for Lakes

EPA is proposing the following numeric nutrient criteria and geochemical
classifications for Florida’s lakes classified as Class I or III
waters under Florida law (Rule 62-302.400, F.A.C.): 

A	B	C	D	E	F

Long Term Average Lake Color and Alkalinity	Chlorophyll a f  (g/L) a
Baseline Criteria b	Modified Criteria

 (within these bounds) c



TP (mg/L) a	TN (mg/L) a	TP (mg/L) a	TN (mg/L) a

Colored Lakes

> 40 PCU	20 	0.050	1.23	0.050-0.157	1.23-2.25

Clear Lakes, Alkaline

≤ 40 PCU d and > 50 mg/L CaCO3 e	20	0.030	1.00	0.030-0.087	1.00-1.81

Clear Lakes, Acidic

≤ 40 PCU d and ≤ 50 mg/L CaCO3 e	6	0.010	0.500	0.010-0.030
0.500-0.900

a Concentration values are based on annual geometric mean not to be
surpassed more than once in a three-year period.  In addition, the
long-term average of annual geometric mean values shall not surpass the
listed concentration values.  (Duration = annual; Frequency = not to be
surpassed more than once in a three-year period or as a long-term
average).

b Baseline criteria apply unless data are readily available to calculate
and apply lake-specific, modified criteria as described below in
footnote c and the Florida Department of Environmental Protection issues
a determination that a lake-specific modified criterion is the
applicable criterion for an individual lake.  Any such determination
must be made consistent with the provisions in footnote c below.  Such
determination must also be documented in an easily accessible and
publicly available location, such as an official State Web site.

c  If chlorophyll a is below the criterion in column B and there are
representative data to calculate ambient-based, lake-specific, modified
TP and TN criteria, then FDEP may calculate such criteria within these
bounds from ambient measurements to determine lake-specific, modified
criteria pursuant to CWA section 303(c).  Modified TN and TP criteria
must be based on at least three years of ambient monitoring data with
(a) at least four measurements per year and (b) at least one measurement
between May and September and one measurement between October and April
each year.  These same data requirements apply to chlorophyll a when
determining whether the chlorophyll a criterion is met for purposes of
developing modified TN and TP criteria.  If the calculated TN and/or TP
value is below the lower value, then the lower value is the
lake-specific, modified criterion. If the calculated TN and TP value is
above the upper value, then the upper value is the lake-specific,
modified criterion.  Modified TP and TN criteria may not exceed criteria
applicable to streams to which a lake discharges.  If chlorophyll a is
below the criterion in column B and representative data to calculate
modified TN and TP criteria are not available, then the baseline TN and
TP criteria apply.  Once established, modified criteria are in place as
the applicable WQS for all CWA purposes.  

d Platinum Cobalt Units (PCU) assessed as true color free from
turbidity.  Long-term average color based on a rolling average of up to
seven years using all available lake color data.

e If alkalinity data are unavailable, a specific conductance of 250
micromhos/cm may be substituted.

f Chlorophyll a is defined as corrected chlorophyll, or the
concentration of chlorophyll a remaining after the chlorophyll
degradation product, phaeophytin a, has been subtracted from the
uncorrected chlorophyll a measurement.

The following section describes the methodologies EPA used to develop
its proposed numeric nutrient criteria for lakes.  EPA is soliciting
comments and scientific data regarding the proposed criteria for lakes
and their derivation.  Section III.B(4) describes one alternative
approach and two supplementary modifications considered by the Agency in
developing this lakes proposal.  EPA solicits comments and data on that
approach and those modifications.

(2)  Methodologies for Deriving EPA’s Proposed Criteria for Lakes 

The process used to develop proposed numeric nutrient criteria for a
range of diverse waters begins with grouping those waters into
categories that generally have a common response to elevated levels of
the stressor pollutants, in this case TN and TP.  The following sections
provide a discussion of 1) the lake classification approach for this
proposal, 2) identification of an appropriate response variable and the
levels of that variable that indicate or represent healthy aquatic
conditions associated with each water body classification, and 3) the
concentrations of TN and TP that correspond to protective levels of the
response variable, in this case, chlorophyll a.  

EPA has recommended that nutrient criteria include both causal (e.g., TN
and TP) and response variables (e.g., chlorophyll a and some measure of
clarity) when establishing numeric nutrient criteria for water bodies. 
EPA recommends causal variables, in part, to have the means to develop
source control targets and, in part, to have the means to assess water
body conditions with knowledge that responses can be variable,
suppressed, delayed, or expressed at different locations.  EPA
recommends response variables, in part, to have a means to assess water
body conditions that synthesize the effect of causal variables over
time, recognizing the daily, seasonal, and annual variability in
measured nutrient levels.  The ability to establish protective criteria
for both causal and response variables depends on available data and
scientific approaches to evaluate these data.  For its lake criteria,
EPA is proposing causal variables for TN and TP and a response variable
for chlorophyll a.  For water clarity, Florida has criteria for
transparency and turbidity, applicable to all Class I and III waters,
expressed in terms of a measurable deviation from natural background
(Rules 32-302.530(67) and (69), F.A.C.).  For further information on
this topic, refer to EPA’s TSD for Florida’s Inland Waters.  

Interested readers should consult EPA TSD for Florida’s Inland Waters,
Chapter 1:  Methodology for Deriving U.S. EPA’s Proposed Criteria for
Lakes, for more detailed information, data, and graphs supporting the
development of the proposed lake criteria.

(a)  Methodology for Proposed Lake Classification

	

Based on analyses of geochemical influences in Florida’s lakes, EPA
proposes the following classification scheme for Florida lakes: 1)
Colored Lakes > 40 Platinum Cobalt Units (PCU), 2) Clear Lakes ≤ 40
PCU with alkalinity > 50 mg/L calcium carbonate (CaCO3), and 3) Clear
Lakes ≤ 40 PCU with alkalinity ≤ 50 mg/L CaCO3. 

Following original work conducted by FDEP, EPA considered several key
characteristics to categorize Florida’s lakes and tailor numeric
nutrient criteria, recognizing that different types of lakes in Florida
may respond differently to nutrients.  Many of Florida’s lakes contain
dissolved organic matter leached from surface vegetation that colors the
water.  More color in a lake limits light penetration within the water
column, which in turn limits algal growth.  Thus, in lakes with colored
water, higher levels of nutrients may occur without exceeding desired
algal levels.  EPA evaluated the relationships between nutrients and
algal responses for these waters (as measured by chlorophyll a
concentration), which indicated that water color influences algal
responses to nutrients.  Based on this analysis, EPA found color to be a
significant factor for categorizing lakes.  More specifically, EPA found
the correlations between nutrients and chlorophyll a concentrations to
be stronger and less variable when lakes were categorized into two
distinct groups based on a threshold of 40 PCU.   This threshold is
consistent with the distinction between clear and colored lakes long
observed in Florida.  Different relationships between nutrients and
chlorophyll a emerged when lakes were characterized by color, with clear
lakes demonstrating greater sensitivity to nutrients as would be
predicted by the increased light penetration, which promotes algal
growth.    

Within the clear lakes category, where color is not generally the
controlling factor in algal growth, EPA evaluated alkalinity as an
additional distinguishing characteristic.  Calcium carbonate (CaCO3),
dissolved from limestone formations and calcareous soils, affects the
alkalinity and pH of groundwater that feeds into lakes.  Alkalinity and
pH increase when water is in contact with limestone or limestone-derived
soil.  Limestone is also a source of TP, and lakes that are higher in
alkalinity in Florida are often associated with naturally elevated TP
levels.  These types of lakes are often in areas of the State where the
underlying geology includes limestone.  The alkalinity (measured as
CaCO3) of Florida clear lakes ranges from zero to well over 200 mg/L. 
FDEP’s Nutrient Criteria Technical Advisory Committee (TAC) evaluated
available data from Florida lakes and concluded that 50 mg/L alkalinity
as CaCO3 is an appropriate threshold above which associated nutrient
levels would be expected to be significantly elevated among clear lakes.
 EPA concluded that FDEP’s proposed approach of using 50 mg/L
alkalinity as CaCO3 is an appropriate distinguishing characteristic in
clear lakes in Florida because lakes with alkalinity ≤50 CaCO3
represents a comprehensive group of lakes that may be naturally
oligotrophic.  Thus, EPA proposes to classify Florida clear lakes as
either acidic (≤50 mg/L alkalinity as CaCO3) or alkaline (>50 mg/L
alkalinity as CaCO3).  

 EPA recognizes that in certain cases FDEP may not have historic
alkalinity data on record to classify a particular clear lake as either
alkaline or acidic.  When alkalinity data are unavailable, EPA proposes
a specific conductivity threshold of 250 microSiemens per centimeter
(S/cm) as a substitute for the threshold of 50 mg/L alkalinity as
CaCO3.  Specific conductivity is a measure of the ionic activity in
water and a data analysis performed by FDEP and re-examined by EPA found
that a specific conductivity threshold value of 250 S/cm is
sufficiently correlated with alkalinity to serve as a surrogate measure.
 Of these two measures, alkalinity is the preferred parameter to measure
because it is less variable and therefore, a more reliable indicator,
and also because it is a more direct measure of the presence of
underlying geology associated with elevated nutrient levels.

EPA solicits comment on the proposed categorization scheme and
associated thresholds used to classify Florida’s lakes.  Please see
Section III.B(4)(b) below in which EPA invites comment on alternative
lake categorization approaches that EPA considered, in particular, those
approaches with respect to alkalinity classification and lakes occurring
in sandhills of northwestern and central Florida.  

(b)  Methodology for Proposed Chlorophyll a Criteria

Because excess algal growth is associated with degradation in aquatic
life and because chlorophyll a levels are a measure of algal growth, EPA
is using chlorophyll a levels as indicators of healthy biological
conditions, supportive of aquatic life in each of the categories of
Florida’s lakes described above.  EPA found multiple lines of evidence
supporting chlorophyll a criteria as an effective indicator of ambient
conditions that would be protective of Florida’s aquatic life use in
lakes.  These lines of evidence included trophic state of lakes,
historical reference conditions in Florida lakes, and model results.

As a primary line of evidence, EPA reviewed and evaluated the Trophic
State Index (TSI) information in deriving chlorophyll a criteria that
are protective of designated aquatic life uses in Florida’s lakes. 
The TSI quantifies the degree of eutrophication (oligotrophic,
mesotrophic, eutrophic) in a water body based on observed measurements
of nutrients and chlorophyll a.  These types of boundaries are commonly
used in scientific literature and represent an established, scientific
classification system to describe current status and natural
expectations for lake conditions with respect to nutrients and algal
productivity.  EPA’s review of TSI studies, indicated that in
warm-water lakes such as those in Florida, TSI values of 50, 60, and 70
are associated with chlorophyll a concentrations of 10, 20, and 40
micrograms per liter (µg/L), respectively.  Studies indicated that
mesotrophic lakes in Florida have TSI values ranging from 50 to 60 and
eutrophic lakes have TSI values ranging from 60 to 70.  Thus a TSI value
of 60 (chlorophyll a concentration of 20 µg/L) represents the boundary
between mesotrophy and eutrophy.  EPA concluded that mesotrophic status
is the appropriate expectation for colored and clear alkaline lakes
because they receive significant natural nutrient input and support a
healthy diversity of aquatic life in warm, productive climates such as
Florida, and mesotrophy represents a lake maintaining a healthy balance
between benthic macrophytes (i.e., plants growing on the lake bottom)
and algae in such climates under such conditions.  However, clear acidic
lakes in Florida do not receive comparable natural nutrient input to be
classified as mesotrophic, and for those lakes, EPA has developed
criteria that correspond to an oligotrophic status.  Oligotrophic lakes
support less algal growth and have lower chlorophyll a levels.  Studies
indicate that a TSI value of 45 reflects an approximate boundary between
oligotrophy and mesotrophy (corresponding to chlorophyll a at about 7
µg/L).  EPA requests comment on these conclusions regarding
oligotrophic and mesotrophic status expectations for these categories of
Florida lakes.

Another line of evidence that supports EPA’s proposed chlorophyll a
criteria is historical reference conditions.  Diatoms are a very common
type of free-floating algae (i.e. phytoplankton) that have shells or
“frustules” made of silica that are preserved in the fossil record. 
Diatoms preserved in lake sediments can be used to infer chlorophyll a
levels in lakes prior to any human disturbance.  Paleolimnological
studies that examined preserved diatom frustules in Florida lake
sediments indicate that historical levels of chlorophyll a are
consistent with mesotrophic expectations derived from the TSI studies
described above, with chlorophyll a levels falling just below the
selected criterion for mesotrophic lakes.  (These studies did not
evaluate lakes expected to be naturally oligotrophic so there is no
comparable information for those lakes).   

In addition to this evidence, EPA used information from the application
of a Morphoedaphic Index (MEI) model that predicts nutrient and
chlorophyll a concentrations for any lake given its depth, alkalinity,
and color to support the proposed chlorophyll a criteria.  Scientists
from the St. John’s Water Management District presented modeling
results for various Florida lakes in each colored and clear category at
the August 5, 2009 meeting of the Nutrient Criteria TAC in Tallahassee. 
In addition to predicting natural or reference conditions, these
scientists used the model to predict chlorophyll a and TP concentrations
associated with a 10% reduction in water transparency for a set of lakes
with varying color levels and alkalinities.  Because submerged aquatic
vegetation is dependent on light, maintaining a lake’s historic
balance between algae and submerged aquatic plants requires maintaining
overall water transparency.  The risk of disrupting the balance between
algae and submerged aquatic plants increases when reductions in
transparency exceed 10%.  The MEI predictions corroborated the results
from lake TSI studies and investigations of paleolimnological reference
conditions because natural or reference predictions (i.e., a “no
effect” level) were generally below selected criteria levels and 10%
transparency loss predictions (i.e., a “threshold effect” level)
were at or slightly above selected criteria levels.  EPA considered
these lines of evidence to develop the proposed chlorophyll a criteria,
discussed below by lake class:

(i) Colored Lakes:  EPA proposes a chlorophyll a criterion of 20 µg/L
in colored lakes to protect Florida’s designated aquatic life uses. 
As indicated by the warm-water TSI studies discussed above, chlorophyll
a concentrations of 20 µg/L represent the boundary between mesotrophy
and eutrophy.  Because mesotrophy maintains a healthy balance of plant
and algae populations in these types of lakes, limiting chlorophyll a
concentrations to 20 µg/L would, therefore, protect colored lakes in
Florida from the adverse impacts of eutrophication.  Paleolimnological
studies of six colored lakes in Florida demonstrated natural (i.e.,
before human disturbance) chlorophyll a levels in the range of 14-20
µg/L and the MEI model predicted reference chlorophyll a concentrations
of 1-25 µg/L for a set of colored lakes in Florida.  The model also
predicted that concentrations of chlorophyll a ranging from 15-36 µg/L
in individual lakes would result in a 10% loss of transparency (all but
two lakes were above 20 µg/L).  Because of natural variability, it is
typical for ranges of natural or reference conditions to overlap with
ranges of where adverse effects may begin occurring (such as the 10%
transparency loss endpoint) for any sample population of lakes.  In
addition, these modeling results, as with any line of evidence, have
uncertainty associated with any individual lake prediction.  Given these
considerations, EPA found that because the clear majority (eight of
eleven) of lakes had predicted natural or referenced conditions below 20
µg/L chlorophyll a and the clear majority (nine of eleven) of lakes had
predicted 10% transparency loss above 20 µg/L chlorophyll a, these
results supported the TSI-based proposed chlorophyll a criterion.  

(ii) Clear, Alkaline Lakes:  EPA proposes a chlorophyll a concentration
of 20 µg/L in clear, alkaline lakes to protect Florida’s designated
aquatic life uses.  As noted in Section III.B(2)(a), alkalinity and TP
are often co-occurring inputs to Florida lakes because of the presence
of TP in limestone, which is often a feature of the geology in Florida. 
Clear, alkaline lakes, therefore, are likely to be naturally
mesotrophic.  EPA’s analysis determined that aquatic life in clear,
alkaline lakes is protected at similar chlorophyll a levels as colored
lakes (at the TSI boundary between mesotrophy and eutrophy).  The MEI
model predicted reference chlorophyll a concentrations of 12-24 µg/L
for a set of clear, alkaline lakes in Florida, and predicted a 10% loss
of transparency when chlorophyll a concentrations ranged from 19-33
µg/L.  Similar to the results for colored lakes, half of the clear,
alkaline lakes had predicted natural or referenced conditions at or
below 20 µg/L chlorophyll a and all but one clear, alkaline lake had
predicted 10% transparency loss above 20 µg/L chlorophyll a.  Thus, EPA
found this evidence to be supportive of the proposed chlorophyll a
criterion.  EPA solicits comment on this chlorophyll a criterion and the
evidence EPA used to support the criterion.

(iii) Clear, Acidic Lakes:  EPA proposes a chlorophyll a concentration
of 6 µg/L in clear, acidic lakes to ensure balanced natural populations
of flora and fauna (i.e., aquatic life) in these lakes.  In contrast to
colored lakes and clear, alkaline lakes, this category of lakes does not
receive significant natural nutrient inputs from groundwater or other
surface water sources. EPA has thus based the proposed criteria on an
expectation that these lakes should be oligotrophic in order to support
balanced natural populations of flora and fauna.  Some of Florida’s
clear, acidic lakes, in the sandhills in northwestern and central
Florida, have been identified as extremely oligotrophic with chlorophyll
a levels of less than 2 µg/L.  As discussed above, warm water TSI
studies suggest a chlorophyll a level of approximately 7 µg/L at the
oligotrophic-mesotrophic boundary.

In July 2009, FDEP proposed a chlorophyll a criterion for clear, acidic
lakes of 9 μg/L.   In comments sent to EPA via email in October 2009,
FDEP reported that the Nutrient TAC suggested in June 2009 that
maintaining chlorophyll a below 10 μg/L in clear, acidic lakes would be
protective of the designated use, because a value of <10 μg/L would
still be categorized as oligotrophic.  However, EPA’s review of the
TSI categorization based on the work of Salas and Martino (1991) on warm
water lakes indicates that a chlorophyll a of 10 μg/L (TSI of 50) would
better represent the central tendency of the mesotrophic category rather
than the oligotrophic-mesotrophic boundary.  In the October 2009
comments, FDEP also presented an analysis of lake data that showed lack
of correlation between an index of benthic macroinvertebrate health and
chlorophyll a levels in the range of 5-10 µg/L as supporting evidence
for a chlorophyll a criterion of 9 ug/L in clear acidic lakes.  However,
within this small range of chlorophyll a, it is not surprising that a
correlation with an indicator responsive to numerous aspects of natural
conditions and stressors such as benthic macroinvertebrate health would
not exhibit a clear statistical relationship.  Importantly, there was
some evidence of meaningful distinctions within the range of 5-10 µg/L
chlorophyll a based on endpoints more directly responsive to nutrients. 
In this case, the MEI model predicted reference chlorophyll a
concentrations within the range of 1.4-7.0 µg/L (with seven of the
eight values below 5 µg/L) for a set of clear, acidic lakes in Florida,
and predicted a 10% loss of transparency when chlorophyll a
concentrations ranged from 5.6-11.8 µg/L (with five of the eight values
below 7 µg/L).  All but one of the clear, acid lakes had predicted
natural or reference conditions below 6 µg/L chlorophyll a and the
majority (six of eight) of clear, alkaline lakes had predicted 10%
transparency loss above 6 µg/L chlorophyll a.  Given available
information on reference condition and predicted effect levels, EPA
adjusted the approximate oligotrophic-mesotrophic boundary value of 7
µg/L slightly downward to 6 µg/L as the proposed chlorophyll a
criterion.  For determining the proposed chlorophyll a criterion in the
three lake categories, only in this case for clear, acid lakes did EPA
use reference condition information and predicted effect levels for more
than just support of the value coming from the TSI-based line of
evidence, and in this case EPA deviated from that value by only 1 µg/L.
 

PA specifically solicits comment on the chlorophyll a criterion of 6
ug/L and the evidence EPA used to support the criterion.  EPA also
solicits comment on whether a higher criterion of 9 ug/L, as proposed by
Florida in its July 2009 proposed nutrient WQS, would be fully
protective of clear acidic lakes, and the scientific basis for such a
conclusion.  

 (c)  Methodology for Proposed Total Phosphorus (TP) and Total Nitrogen
(TN) Criteria in Lakes

EPA proposes TP and TN criteria for each of the classes of lakes
described in Section III.B(2)(a).  The proposed TP and TN criteria are
based principally on independent statistical correlations between TN and
chlorophyll a, and TP and chlorophyll a for clear and colored lakes in
Florida.  Each data point used in the statistical correlations
represents a geometric mean of samples taken over the course of a year
in a particular Florida lake.  After establishing the protective levels
of chlorophyll a as 20 µg/L for colored lakes and clear alkaline lakes
and 6 µg/L for clear acidic lakes, EPA evaluated the data on TN and TP
concentrations associated with these chlorophyll a levels and the
statistical analyses performed by FDEP in support of the State’s
efforts to develop numeric nutrient criteria.

These analyses showed that the response dynamics of TN and TP with
chlorophyll a were different for colored versus clear lakes, as would be
expected because color blocks light penetration in the water column and
limits algal growth.  These analyses also showed that the correlation
relationships for TN and TP compared with chlorophyll a in acidic and
alkaline clear lakes were comparable, as would be expected because
alkalinity does not affect light penetration.  These analyses are
available in EPA’s TSD for Florida’s Inland Waters, Chapter 1: 
Methodology for Deriving U.S. EPA’s Proposed Criteria for Lakes.  

The difference between clear, acidic and clear, alkaline lakes is that
clear, alkaline lakes naturally receive more nutrients and, therefore,
have an expected trophic status of mesotrophic to maintain a healthy
overall production and balance of plants and algae.  On the other hand,
clear, acidic lakes naturally receive much lower nutrients and,
therefore, have an expected trophic status of oligotrophic to maintain a
healthy, but lower than mesotrophic, level of plant and algae aquatic
life.  Because of the different expectations for trophic condition,
different chlorophyll a criteria are appropriate (as mentioned earlier,
chlorophyll a is a measure of algal production).  Although clear,
alkaline lakes and colored lakes have the same proposed chlorophyll a
criterion, they will have different TP and TN criteria because of the
effect of color on light penetration and algal growth.  

The TN and TP values EPA is proposing are based on the lower and upper
TN and TP values derived from the 50th percentile prediction interval of
the regression (i.e., best-fit line) through the chlorophyll a and
corresponding TN or TP values plotted on a logarithmic scale.  In other
words, the prediction interval displays the range of TN and TP values
typically associated with a given chlorophyll a concentration.  At any
given chlorophyll a concentration, there will be a lower TN or TP value
and an upper TN or TP value corresponding to this prediction interval. 
EPA agrees with the FDEP approach that uses the 50th percentile
prediction interval because it effectively separates the data into three
distinct groups.  This analysis of the substantial lake data collected
by Florida indicates that the vast majority of monitored lakes with
nutrient levels below the lower TN or TP value have associated
chlorophyll a values below the protective chlorophyll a threshold level.
 Similarly, the vast majority of monitored lakes with measured nutrient
levels above the upper TN or TP value have associated measured
chlorophyll a values above the protective chlorophyll a threshold level.
 Between these TN and TP bounds, however, this analysis indicates that
monitored lakes are equally likely to be above or below the protective
chlorophyll a threshold level.  Setting TN and TP criteria based on the
bounds of the 50th percentile prediction interval, in conjunction with
lake-specific knowledge of whether the lake chlorophyll a threshold is
met, accounts for the naturally variable behavior of TN and TP while
ensuring protection of aquatic life. 

EPA’s proposed criteria framework sets a protective chlorophyll a
threshold and TN and TP criteria at the lower values of the range
defined by the 50th percentile prediction interval for the three
different categories of lakes as “baseline” criteria.  The criteria
framework also provides flexibility for FDEP to derive lake-specific,
modified TN and TP criteria within the bounds of the upper and lower
values based on at least three years of ambient measurements where a
chlorophyll a threshold is not exceeded.  More specifically, if the
chlorophyll a criterion for an individual lake is met for a period of
record of at least three years, then the corresponding TN and TP
criteria may be derived from ambient measurements of TN and TP from that
lake within the bounds of the lower and upper values of the prediction
interval discussed above.  Both the ambient chlorophyll a levels as well
as the corresponding ambient TN and TP concentrations in the lake must
be established with at least three years worth of data.  EPA’s
proposed rule provides that these modified criteria need to be
documented by FDEP.  EPA’s rule, however, does not require that FDEP
go through a formal SSAC process subject to EPA review and approval.  

In this proposed rule, EPA specifies that in no case, however, may the
modified TN and TP criteria be higher than the upper value specified in
the criteria bounds, nor lower than the lower value specified in the
criteria bounds.  In addition to nutrients, chlorophyll a in a lake may
be limited by high water color, zooplankton grazing, mineral turbidity,
or other unknown factors.  In the absence of detailed, site-specific
knowledge, the upper values represent increasing risk that chlorophyll a
will exceed its criterion value.  To maintain the risk at a manageable
level, the upper values are not to be exceeded.  EPA requests comments
on this approach.  EPA also requests comment on whether the rule should
specify that the modified TN and TP criteria be set at levels lower than
the lower value of the criteria bounds if that is what is reflected in
the outcome of the ambient-based calculation.

EPA’s proposed approach for TN and TP criteria in lakes reflects the
natural variability in the relationship between chlorophyll a
concentrations and corresponding TP and TN concentrations that may exist
in lakes.  This variability remains even after some explanatory factors
such as color and alkalinity are addressed by placing lakes in different
categories based on color and alkalinity because other natural factors
play important roles.  Natural variability in the physical, chemical,
and biological dynamics for any individual lake may result from
differences in geomorphology, concentrations of other constituents in
lake waters, hydrological conditions and mixing, and other factors.

PA requests comment on the requirement of three years worth of data for
both chlorophyll a and TN and TP in order to use this option. 
Specifically, are there situations in which less than three years of
data might be adequate for an adjusted TN or TP criterion?

EPA selected the proposed TP and TN criteria based on the relationships
with chlorophyll a described above.  However, the MEI modeling results
described in Section III.B(2)(b) also provide additional support for the
TP criteria selection.  The MEI predicted a 10% transparency loss when
TP concentrations ranged from 0.053-0.098 mg/L in colored lakes (with
one predicted value at 0.037 mg/L), from 0.038-0.068 mg/L in clear,
alkaline lakes, and from 0.012-0.024 mg/L in clear, acidic lakes.  All
but one of these predicted values are within the lower and upper bounds
of the proposed TP criteria.  The MEI modeling results did not address
TN.

(d)  Proposed Criteria:  Duration and Frequency

Numeric criteria include magnitude (i.e., how much), duration (i.e., how
long), and frequency (i.e., how often) components.  Beginning with
EPA’s 2004 Integrated Report Guidance, EPA has used the term
“exceeding criteria” to refer to situations where all criteria
components are not met.  The term “digression” refers to an ambient
level that goes beyond a level specified by the criterion-magnitude
(e.g., in a given grab sample).  The term “excursion” refers to
conditions that do not meet the criterion-magnitude and
criterion-duration, in combination.  A criterion-frequency specifies the
maximum rate at which “excursions” may occur.  

For the chlorophyll a, TN, and TP criteria for lakes, the
criterion-magnitude values (expressed as a concentration) are provided
in the table and the criterion-duration (or averaging period) is
specified as annual.  The criterion-frequency is
no-more-than-once-in-a-three-year period.  In addition, the long-term
arithmetic average of annual geometric mean values shall not exceed the
criterion-magnitude values (concentration values).

Appropriate duration and frequency components of criteria should be
based on how the data used to derive the criteria were analyzed, and
what the implications are for protection of designated uses given the
effects of exposure at the specified criterion concentration for
different periods of time and recurrence patterns.  For lakes, the
stressor-response relationship was based on annual geometric means for
individual years at individual lakes.  The appropriate duration period
is therefore annual.  The key question is whether this annual geometric
mean needs to be met every year, or if some allowance for a particular
year to exceed the applicable criterion could still be considered
protective.  

Data that contribute to the analysis of TSI, as well as data generated
from supporting paleolimnological studies and MEI modeling, typically
represent periods of time greater than a single year.  Moreover, many of
the models and analyses that form the basis of TSI results are designed
to represent the “steady-state,” or long-term stable water quality
conditions.  However, researchers have suggested caution in applying
steady-state assumptions to lakes with long residence times.  In other
words, the effects of spikes in annual loading could linger and disrupt
the steady-state in some lakes.  As a result, EPA is proposing two
expressions of allowable frequency, both of which are to be met.  First,
EPA proposes a no-more-than-one-in-three-years excursion frequency for
the annual geometric mean criteria for lakes.  Second, EPA proposes that
the long-term arithmetic average of annual geometric means not exceed
the criterion-magnitude concentration.  EPA anticipates that Florida
will use its standard assessment periods as specified in Rule 62-303,
F.A.C. (Impaired Waters Rule) to implement this second provision.  These
selected frequency and duration components recognize that hydrological
variability will produce variability in nutrient regimes, and individual
measurements may exceed the criteria magnitude concentrations. 
Furthermore, they balance the representation of underlying data and
analyses based on the central tendency of many years of data (i.e., the
long-term average component) with the need to exercise some caution to
ensure that lakes have sufficient time to process individual years of
elevated nutrient levels and avoid the possibility of cumulative and
chronic effects (i.e., the no-more-than-one-in-three-year component). 
More information on this specific topic is provided in EPA’s TSD for
Florida’s Inland Waters, Chapter 1:  Methodology for Deriving U.S.
EPA’s Proposed Criteria for Lakes.

) a criterion-frequency expressed as meeting allowable magnitude and
duration as a long-term average only.  EPA further requests comment on
whether an expression of the criteria in terms of an arithmetic average
of annual geometric mean values based on rolling three-year periods of
time would also be protective of the designated use. 

 (e)  Application of Lake-specific, Ambient Condition-based Modified TP
and TN Criteria   

As described in Section III.B(2)(c), EPA is proposing a framework that
uses both the upper and lower bounds of the 50th percentile prediction
interval to allow the derivation of modified TP and TN lake-specific
criteria to account for the natural variability in the relationship
between chlorophyll a and TP and TN that may exist in certain lakes. 
The proposed rule would allow FDEP to calculate ambient modified
criteria for TN and TP based on at least three years of ambient
monitoring data with (a) at least four measurements per year and (b) at
least one measurement between May and September and one measurement
between October and April each year.  If a calculated modified TN and TP
criterion is below the lower value, then the lower value is the
criteria.  If a calculated modified TN and TP criterion is above the
upper value, then the upper bound is the criteria.  Calculated modified
TP and TN values may not exceed criteria applicable to streams to which
a lake discharges.

EPA’s proposed rule provides that FDEP must document these modified
criteria and establish them in a manner that clearly recognizes their
status as the applicable criterion for a particular lake so that the
public and all regulatory authorities are aware of its existence. 
However, EPA’s proposed rule does not require that FDEP go through a
formal SSAC process subject to EPA review and approval.  (For more
information on the SSAC process, please refer to Section V of this
proposal).  EPA believes such modified criteria do not need to go
through the SSAC process because the conditions under which they are
applicable are clearly stated in the proposed rule and the methods of
calculation are clearly laid out so that the outcome is predictable and
transparent.  By providing a specific process for deriving modified
criteria within the WQS rule itself, each individual outcome of this
process is an effective WQS for CWA purposes and does not need separate
approval by EPA.

One technical concern is the extent to which the variability in the data
relating chlorophyll a levels to TN and TP levels truly reflects
differences between lakes, as opposed to temporal differences in the
conditions in the same lake.  To address this issue, EPA verified that
the observed variability in the supporting analysis was indeed
predominantly “across lake” variability, not “within lake”
variability.  

Another technical concern is that there may be a time lag between the
presence of high nutrients and the biological response.  In a study of
numerous lakes, researchers found that there was often a lag period of a
few years in chlorophyll a response to changes in nutrient loading, but
that there was correlation between chlorophyll a and nutrient
concentrations on an annual basis.  The difference between nutrient
loading and nutrient concentration as a function of time is related to
the hydraulic retention time of a lake.  EPA proposed TN and TP criteria
as concentration values with an annual averaging period, so any time lag
in response would not be expected to confound the derivation of modified
criteria.  Furthermore, EPA is proposing to require three years worth of
data, which would reflect any short time lag in response.

A third technical concern is the presence of temporary or long-term
site-specific factors that may suppress biological response, such as the
presence of grazing zooplankton, excess sedimentation that blocks light
penetration, extensive canopy cover, or seasonal herbicide use that
impedes proliferation of algae.  If any of these suppressing factors are
removed, then nutrient levels may result in a spike in algal production
above protective levels.

PA also requests comment on whether less data or a different
specification would be sufficient to establish this different
relationship in a particular lake, e.g. whether revised TN and TP
ambient criteria should be allowed when the chlorophyll a criterion
concentration has been exceeded once in three years. 

Application of the ambient calculation provision has implications for
assessment and permitting because the outcome of applying this provision
is to establish alternate numeric TN and TP values as the applicable
numeric nutrient criteria for TN and TP.  For accountability and
tracking purposes, the State would need to document in a publicly
available and accessible manner, such as on an official State Web site,
the result of the ambient calculation for any given lake.  The State may
wish to issue a public notification, with an opportunity to submit
additional data and check calculations, to ensure an appropriate value
is determined.  The State may wish to publicly certify the outcome via a
Secretarial order or some other official statement of intent and
applicability.  EPA’s preference is that once modified criteria are
developed, they remain the applicable criteria for the long-term.  The
State has the flexibility to revise the criteria, but the expectation is
that they will not be a continuously moving target for implementation
purposes.  As an example of how the lakes criteria might work in
practice, consider a colored lake which meets the chlorophyll a
criterion.  If FDEP established a modified TP criterion of 0.110 mg/L
and subsequent monitoring showed levels at 0.136 mg/L, that lake would
not be considered attaining the applicable criteria for CWA purposes
(unless the State goes through the process of establishing a revised
modified criterion).

The permitting authority would use publicly certified modified TN or TP
criteria to develop water quality-based effluent limits (WQBELs) that
derive from and comply with applicable WQS.  In this application, the
permit writer would use the modified ambient criterion, computed as
described above, as the basis for any reasonable potential analysis or
permit limit derivation.  In this case, as in any other case, EPA
expects the details to be fully documented in the permit fact sheet.

This type of ambient calculation provision based on meeting response
criteria applicable to the assessed water may not be appropriate when
the established TN and TP criteria are serving to maintain and protect
waters downstream.  To address this concern, EPA proposes that
calculated TP and TN values in a lake that discharges to a stream may
not exceed criteria applicable to the stream to which a lake discharges.
 EPA requests comment on this provision.

(3)  Request for Comment and Data on Proposed Approach

EPA is soliciting comment on the approaches described in this proposal,
the data underlying those approaches, and the proposed criteria.  EPA
will evaluate all data and information submitted by the close of the
public comment period for this rulemaking with regard to nutrient
criteria for Florida’s lakes.  For the application of the modified
ambient calculation provision, EPA is seeking comment on allowing the
calculation to occur one time only, based on an adequate period of
record, and then holding that value as the protective TP or TN criteria
for future assessment and implementation purposes.  EPA is also seeking
comment on whether to require an ambient chlorophyll a level
demonstrated to be below the chlorophyll a threshold criterion for at
least three years become the protective chlorophyll a criterion for a
lake subject to the modified ambient calculation provision (i.e.,
whether to require a more stringent chlorophyll a criterion if three
years of data show that the more stringent level reflects current
conditions in the lake).  EPA also requests comment on whether an
additional condition for being able to apply a modified criterion
include continued ambient monitoring and verification that chlorophyll a
levels remain below the protective criterion.  EPA could specify that
modified criteria remain in effect as long as FDEP subsequently conducts
monthly (or some other periodic) monitoring of the lake to ensure that
chlorophyll a levels continue to meet the protective criterion.  If this
monitoring is not conducted and documented, EPA could specify that the
baseline criterion would become the applicable criterion.  Among others,
this provision may address concerns about whether the modified criterion
adequately represents long-term hydrologic variability.  Finally, EPA
requests comment on the appropriate procedure for documenting and
tracking the results of modified criteria that allows transparency,
public access, and accountability.  

(4)  Alternatives Considered by EPA

During EPA’s review of the available data and information for
development of numeric nutrient criteria for Florida’s lakes, EPA
considered and is soliciting comment on an alternative approach to
deriving lakes criteria from the statistical correlation plots and
regression analysis.  The alternative approach would use either the
central tendency values or the lower values associated with the 50th
percentile prediction interval for TN and TP criteria and would not
include the framework to calculate modified TP and TN criteria when the
chlorophyll a criterion is met.  EPA is also seeking comments on the
following two supplementary modifications that EPA considered but did
not include in this proposal: 1) the use of a modified categorization of
lakes in Florida; and 2) the addition of upper percentile criteria with
a different exceedance frequency.

(a)  Single Value Approach to Derive Lakes Criteria - Derive TN and TP
Criteria Using Correlations Associated with the Regression Line or Lower
Value  of the 50th Percentile Prediction Interval  

One alternative means of selecting TN and TP criteria is to use the
regression line (central tendency) to calculate TP and TN concentrations
that correlate to the proposed chlorophyll a criteria for each lake
class.  A second alternative is to use the lower value of the 50th
percentile prediction interval to calculate TP and TN concentrations.
Establishing TP and TN criteria using the central tendency of the
regression line represents the best estimate of TN and TP associated
with a protective chlorophyll a criterion across all lakes, but carries
some risk of being overprotective for some individual lakes and
under-protective for others because of the demonstrated variability of
the data.  On the other hand, establishing TP and TN criteria using the
lower value of the 50th percentile prediction interval will likely be
protective in most cases, but could be overprotective for a greater
number of lakes because the data demonstrate that many lakes achieve the
protective chlorophyll a criterion with higher levels of TN and TP. 
Neither approach accounts for lake-specific natural variability, apart
from that accounted for by color and alkalinity classification. 
However, the correlated TP and TN concentrations within each lake class
at these alternative statistical boundaries would result in single
criteria values for TN and TP, which is an approach that water quality
program managers will have more familiarity.  EPA’s rationale for
proposing a framework that uses both the upper and lower values of the
50th percentile prediction interval to allow the derivation of modified
TN and TP lake-specific criteria rather than either of these single
values was to account for the natural variability in the relationship
between chlorophyll a and TN and TP that may exist in lakes.  EPA
solicits comment, however, on this alternative approach of using single
values for TN and TP criteria in Florida’s lakes.

(b)  Modification to Proposed Lakes Classification 

As discussed in Section III.B(2)(a), EPA used available data to
determine a classification scheme for Florida’s lakes, based on a
color threshold of 40 PCU and a threshold of 50 mg/L alkalinity as
CaCO3.  In its July 2009 numeric nutrient criteria proposal, Florida
considered a similar classification approach based on color and
alkalinity but proposed a chlorophyll a criterion of 9 µg/L to protect
aquatic life in clear, acidic lakes.  As discussed above, EPA believes
that the scientific evidence more strongly supports a chlorophyll a
criterion of 6 µg/L to protect Florida’s clear, acidic lakes that
include the very oligotrophic lakes found in Florida’s sandhills,
principally in three areas: the Newhope Ridge/Greenhead slope north of
Panama City (locally called the Sandhill Lakes region); the
Norfleet/Springhill Ridge just west of Tallahassee, and Trail Ridge
northeast of Gainesville.  However, some stakeholders have suggested
that many lakes in the clear, acidic class (as currently defined) might
be sufficiently protected with a chlorophyll a criterion of  9 µg/L. 
EPA believes the scientific basis for a 9 ug/L chlorophyll a value may
be more applicable to clear acidic lakes other than those in Florida’s
sandhills (i.e., other than those in the Sandhill Lakes region, the
Norfleet/Springhill Ridge just west of Tallahassee and Trail Ridge
northeast of Gainesville).  To address this, EPA could separate clear,
acidic lakes into two categories: one category for clear, acidic lakes
in sandhill regions of Florida, and a second category for clear, acidic
lakes in other areas of the State.  EPA could assign the first category
(clear, acidic sandhill lakes) a chlorophyll a criterion of 6 µg/L and
the second category (clear, acidic non-sandhill lakes) a chlorophyll a
criterion of 9 µg/L.  

PA also notes, as discussed previously, that FDEP recommended a
criterion of 9 µg/L as being protective of all clear acidic lakes,
including sandhill lakes and that the Nutrient Criteria TAC supported
“less than 10 µg/L” as protective.  EPA also requests comment on 9
µg/L chlorophyll a as being protective of all clear acidic lakes,
including sandhill lakes.  

(c)  Modification to Include Upper Percentile Criteria 

EPA is considering promulgating upper percentile criteria for
chlorophyll a, TN, and TP in colored, clear alkaline, and clear acidic
lakes to provide additional aquatic life protection.  Accordingly, EPA
could add that the instantaneous concentration in the lake not surpass
these criterion-magnitude concentrations more than 10% of the time
(criterion-duration: instant; criterion-frequency: 10% of the time). 
EPA derived example upper percentile criteria using the observed
standard deviation from the mean of lake samples meeting the respective
criteria (lower values of the TN and TP ranges) within each lake class. 
Using this example, the calculated criteria-magnitude concentrations for
chlorophyll a, TN, and TP respectively by lake class are: 63 µg/L, 1.5
mg/L and 0.09 mg/L for colored lakes; 48 µg/L, 1.8 mg/L and 0.05 mg/L
for clear, alkaline lakes; and 15 µg/L, 0.6 mg/L and 0.02 mg/L for
clear, acidic lakes.  

These criteria would provide the means to protect lakes from episodic
events that increase loadings for significant periods of time during the
year, but are balanced out by lower levels in other parts of the year
such that the annual geometric mean value is met.  EPA chose not to
propose such criteria because of the significant variability of
chlorophyll a, TN, and TP, the variety of other factors that may
influence levels of these parameters in the short-term, and that
significant environmental damage from eutrophication is more likely when
levels are elevated for longer periods of time.  However, EPA solicits
comment on this additional approach of promulgating upper percentile
criteria for chlorophyll a, TN, and TP. 

(5)  Request for Comment and Data on Alternative Approaches

EPA is soliciting comment on the Agency’s proposed approach, as well
as the alternative approach to deriving numeric nutrient criteria for
Florida’s lakes and the supplemental modifications as described in
Section III.B(4).  EPA will evaluate all data and information submitted
by the close of the public comment period for this rulemaking with
regard to nutrient criteria for Florida’s lakes.

C.  Proposed Numeric Nutrient Criteria for the State of Florida’s
Rivers and Streams

(1)  Proposed Numeric Nutrient Criteria for Rivers and Streams

EPA is proposing numeric nutrient criteria for TN and TP in four
geographically distinct watershed regions of Florida’s rivers and
streams (hereafter, streams) classified as Class I or III waters under
Florida law (Rule 62-302.400, F.A.C.).  

Nutrient Watershed Region	Instream Protection Value Criteria

	TN (mg/L) a	TP (mg/L) a

Panhandle b

	0.824	0.043

Bone Valley c

	1.798	0.739

Peninsula d

	1.205	0.107

North Central e

	1.479	0.359

a Concentration values are based on annual geometric mean not to be
surpassed more than once in a three-year period.  In addition, the
long-term average of annual geometric mean values shall not surpass the
listed concentration values.  (Duration = annual; Frequency = not to be
surpassed more than once in a three-year period or as a long-term
average).

b Panhandle region includes the following watersheds: Perdido Bay
Watershed, Pensacola Bay Watershed, Choctawhatchee Bay Watershed, St.
Andrew Bay Watershed, Apalachicola Bay Watershed, Apalachee Bay
Watershed, and Econfina/Steinhatchee Coastal Drainage Area.

c Bone Valley region includes the following watersheds: Tampa Bay
Watershed, Sarasota Bay Watershed, and Charlotte Harbor Watershed.

d Peninsula region includes the following watersheds: Waccasassa Coastal
Drainage Area, Withlacoochee Coastal Drainage Area,
Crystal/Pithlachascotee Coastal Drainage Area, Indian River Watershed,
Caloosahatchee River Watershed, St. Lucie Watershed, Kissimmee River
Watershed, St. John’s River Watershed, Daytona/St. Augustine Coastal
Drainage Area, Nassau Coastal Drainage Area, and St. Mary’s River
Watershed.

e North Central region includes the Suwannee River Watershed.

The following section describes the methodology used to derive the
proposed numeric nutrient criteria for streams.  EPA is soliciting
comments and scientific data and information regarding these proposed
criteria and their derivation.  

(2)  Methodology for Deriving EPA’s Proposed Criteria for Streams

Like other aquatic ecosystems, excess nutrients in streams increases
vegetative growth (plants and algae), and changes the assemblage of
plant and algal species present in the system.  These changes can affect
the organisms that are consumers of algae and plants in many ways.  For
example, these changes can alter the available food resources by
providing more dead plant material versus live plant material, or
providing algae with a different cell size for filter feeders.  These
changes can also alter the habitat structure by covering the stream or
river bed with periphyton (attached algae) rather than submerged aquatic
plants, or clogging the water column with phytoplankton (floating
algae).  In addition, these changes can lead to the production of algal
toxins that can be toxic to fish, invertebrates, and humans.  Chemical
characteristics of the water, such as pH and concentrations of dissolved
oxygen, can also be affected by excess nutrients.  Each of these changes
can, in turn, lead to other changes in the stream community and,
ultimately, to the stream ecology that supports the overall function of
the linked aquatic ecosystem.

Although the general types of adverse effects can be described, not all
of these effects will occur in every stream at all times.  For example,
some streams are well shaded, which would tend to reduce the near-field
effect of excess nutrients on primary production because light, which is
essential for plant or algae growth, does not reach the water surface. 
Some streams are fast moving and pulses of nutrients are swiftly carried
away before any effect can be observed.  However, if the same stream
widens and slows downstream or the canopy that provided shading opens
up, then the nutrients present may accelerate plant and algal biomass
production.  As another example, the material on the bottom of some
streams, referred to as substrate, is frequently scoured from intense
rain storms.  These streams may lack a natural grazing community to
consume excess plant growth and may be susceptible to phytoplankton
algae blooms during periods when water velocity is slower and water
residence time is longer.  The effects of excess nutrients may be subtle
or dramatic, easily captured by measures of plant and algal response
(such as chlorophyll a) or not, and may occur in some locations along a
stream but not others.

Notwithstanding natural environmental variability, there are well
understood and documented analyses and principles about the underlying
biological effects of TN and TP on an aquatic ecosystem.  There is a
substantial and compelling scientific basis for the conclusion that
excess TN and TP will have adverse effects; however, it is often unclear
where precisely the impacts will occur.  The value of regional numeric
nutrient criteria for streams is that the substantial expenditure of
time and scarce public resources to document and interpret inevitable
and expected stream variability on a site-by-site, segment-by-segment
basis (i.e., as in the course of interpreting a narrative WQS for WQBELs
and TMDL estimations) is no longer necessary.  Rather, regional numeric
nutrient criteria for streams allows an expedited and expanded level of
aquatic protection across watersheds and greatly strengthens local and
regional capacity to support and maintain State designated uses
throughout aquatic ecosystems.  In terms of environmental outcomes, the
result is a framework of expectations and standards that is able to
extend the protection needed to restore and maintain valuable aquatic
resources to entire watersheds and associated aquatic ecosystems.  At
the same time, the ability to promulgate SSAC, as well as other
flexibilities discussed in this proposal, allows the State to continue
to address water bodies where substantial data and analyses show that
the regional criteria may be either more stringent than necessary or not
stringent enough to protect designated uses.

As mentioned earlier, to effectively apply this well understood and
documented science, EPA has recommended that nutrient criteria include
both causal (e.g., TN and TP) and response variables (e.g., chlorophyll
a and some measure of clarity) for water bodies.  EPA recommends causal
variables, in part, to have the means to develop source control targets
and, in part, to have the means to assess stream condition with
knowledge that responses can be variable, suppressed, delayed, or
expressed at different locations.  EPA recommends response variables, in
part, to have a means to assess stream condition that synthesizes the
effect of causal variables over time, recognizing the daily, seasonal,
and annual variability in measured nutrient levels.  

The ability to establish protective criteria for both causal and
response variables depends on available data and scientific approaches
to evaluate these data.  Whereas, there are data available for water
column chlorophyll a (phytoplankton) and algal thickness on various
substrates (periphyton) for certain types of streams in Florida, there
are currently no available approaches to interpret these data to infer
scientifically supported thresholds for these nutrient-specific response
variables in Florida streams.  Additionally, in previously published
guidance, EPA has recommended water clarity as a response variable for
numeric nutrient criteria because algal density in a water column
results in turbidity, and thus a related decrease in water clarity can
serve as an indicator of excess algal growth.  For water clarity,
Florida has criteria for transparency and turbidity, applicable to all
Class I and III waters, expressed in terms of a measurable deviation
from natural background (32-302.530(67) and (69), F.A.C.).  Therefore,
EPA is not proposing criteria for any response variable in Florida’s
streams at this time, however, EPA will consider additional data that
becomes available during the comment period.  One approach for deriving
criteria for water quality variables such as a measure for water clarity
or chlorophyll a, could be to apply a statistical distribution approach
to a population of streams for each of the proposed NWRs.  This approach
is further described in previous EPA guidance. 

For Florida streams, EPA has determined that there are sufficient
available data on TN and TP concentrations with corresponding
information on biological condition for a wide variety of stream types
that can be used to derive numeric nutrient criteria for those causal
variables.  EPA used multiple measures of stream condition (or metrics)
that describe the biological condition of the benthic invertebrate
community.  EPA then coupled the stream condition metrics with
associated measurements of TN and TP concentrations to provide the basis
for deriving causal variable numeric nutrient criteria.

EPA’s proposed instream numeric nutrient criteria for Florida’s
streams are based upon EPA’s evaluation of data on TN and TP levels in
rivers and streams that have been carefully evaluated by FDEP, and
subsequently by EPA, on a site-specific basis and identified as
biologically healthy.  EPA’s approach results in numeric criteria that
are protective of the streams themselves.  EPA has determined, however,
that these instream values may not always be protective of the
designated uses in downstream lakes and estuaries.  Therefore, EPA has
also developed an approach for deriving TN and TP values for rivers and
streams to ensure the protection of downstream lakes and estuaries. 
This approach is discussed in Section III.C(6).

(a)  Methodology for Stream Classification: EPA’s Nutrient Watershed
Regions (NWRs)

EPA classified Florida’s streams north of Lake Okeechobee by
separating watersheds with a substantially different ratio of TN and TP
export into Nutrient Watershed Regions (NWR).  The resulting regions
reflect the inherent differences in the natural factors that contribute
to nutrient concentrations in streams (e.g., geology, soil composition,
and/or hydrology).  Reliance on a watershed-based classification
approach reflects the understanding that upstream water quality affects
downstream water quality.  This watershed classification also
facilitates the ability to address the effects of TN and TP from streams
to downstream lakes or estuaries in the same watershed.  

EPA’s classification approach results in four watershed regions: the
Panhandle, the Bone Valley, the Peninsula, and the North Central (for a
map of these regions, refer to the EPA TSD for Florida’s Inland Waters
or the list of watersheds in the table above).  These four regions do
not include the south Florida region (corresponding to FDEP’s
Everglades Bioregion) that is addressed separately in Section III.E
which sets out EPA’s proposed numeric nutrient criteria for canals in
south Florida.  All flowing waters in this region are either a canal or
a wetland.

When classifying Florida’s streams, EPA identified geographic areas of
the State as having phosphorus-rich soils and geology, such as the Bone
Valley and the northern Suwannee River watershed .  As indicated above,
the Bone Valley region and the Suwannee River watersheds are classified
in this proposal as separate NWRs because it is well established that
the naturally phosphorus-rich soils in these areas significantly
influence stream phosphorus concentrations in these watersheds. EPA
would expect from a general ecological standpoint that the associated
aquatic life uses, under these naturally-occurring, nutrient-rich
conditions, would be supported. The Agency requests comment on this
particular classification decision (regions based on phosphorus-rich
soils), as well as an alternate classification approach that would not
separate out the phosphorus-rich watersheds described in this notice. 
The latter approach is similar to the approach proposed by EPA, but
would not result in separate NWRs for the Bone Valley and/or North
Central.  Rather these NWRs would be integrated within the other NWRs.

(b)  The Use of the Stream Condition Index as an Indicator of
Biologically Healthy Conditions

For EPA’s proposed approach, the Agency utilized a multi-metric index
of benthic macroinvertebrate community composition and taxonomic data
known as the Stream Condition Index (SCI) developed by FDEP to assess
the biological health of Florida’s streams.  Of the metrics that
comprise the SCI, some decrease in response to human disturbance-based
stressors, such as excess nutrients; for example, 1) total taxa
richness, 2) richness of Ephemeroptera (mayflies), 3) richness of
Plecoptera (stoneflies), 4) percentage of sensitive taxa, and 5)
percentage of filterers and suspension feeders.  Other metrics increase
in response to human disturbance-based stressors; for example, percent
of very tolerant taxa (e.g., Genera Prostoma, Lumbriculus) and percent
of the dominant taxa (i.e., numerical abundance of the most dominant
taxon divided by the total abundance of all taxa).

The SCI was developed by FDEP in 2004, with subsequent revisions in 2007
to reduce the variability of results.  In order to ensure that data are
produced with the highest quality, field biologists and lab technicians
must follow detailed Standard Operating Procedures (SOPs) and additional
guidance for sampling and data use provided through a FDEP document
entitled “Sampling and Use of the Stream Condition Index (SCI) for
Assessing Flowing Waters: A Primer (DEP-SAS-001/09).”  Field
biologists must pass a rigorous audit with FDEP, and laboratory
taxonomists are regularly tested and must maintain greater than 95%
identification accuracy.  

EPA considered two lines of evidence in determining the SCI range of
scores that would indicate biologically healthy systems.  The first line
of evidence was an evaluation of SCI scores in streams considered by
FDEP to be least-disturbed streams in Florida.  A statistical analysis
balanced the probability of a stream being included in this reference
set with the probability of a stream not being included in this
reference set, and indicated that an SCI score of 40 was an appropriate
threshold.  SCI scores range from 1 to 100 with higher scores indicating
healthier biology.  

A second line of evidence was the result of an expert workshop convened
by FDEP in October 2006.  The workshop included scientists with specific
knowledge and expertise in stream macroinvertebrates.  These experts
were asked to individually and collectively evaluate a range of SCI data
(i.e., macroinvertebrate composition and taxonomic data) and then assign
those data into one of the six Biological Condition Gradient (BCG)
categories, ranging from highly disturbed (Category 6) to pristine
(Category 1).  EPA analyzed the results of these categorical
assignments using a proportional odds regression model that predicts the
probability of an SCI score occurring within one of the BCG categories
by overlapping the ranges of SCI scores associated with each category
from the individual expert assignment.  The results of the analysis
provided support for identifying a range of SCI scores that minimized
the probability of incorrectly assigning a low quality site to a high
quality category, and incorrectly assigning a high quality site to a low
quality category, using the collective judgment of expert opinion.  The
results indicated a range of SCI scores of 40-44 to represent an
appropriate threshold of healthy biological condition.  Please refer to
the EPA TSD for Florida’s Inland Waters for more information on such
topics as EPA’s estimates of the Type I and Type II error associated
with various threshold values.  Thus, two very different approaches
yielded comparable results.  A subsequent EPA statistical analysis
indicated that nutrient conditions in Florida streams within different
regions remain essentially constant within an SCI score range of 40-50
providing further support for a selection of 40 as a threshold that is
sufficiently protective for this application.  The resulting TN and TP
concentrations associated with a SCI score of 40 versus 50 did not
represent a statistical difference and 40 was more in line with other
lines of evidence for a SCI score threshold.

(c)  Methodology for Calculating Instream Protection Values: The
Nutrient Watershed Region Distribution Approach 

EPA evaluated several methodologies, including reference conditions and
stressor-response relationships, to develop values that protect
designated uses of Florida streams instream.  EPA analyzed
stressor-response relationships in Florida streams based on available
data, but, as mentioned above, did not find sufficient scientific
support for their use in the derivation of numeric nutrient criteria for
Florida streams.  More specifically, EPA was not able to demonstrate a
sufficiently strong correlation between the biological response
indicators (e.g., chlorophyll a, periphyton biomass, or SCI) and TN or
TP concentrations.  Thus, the Agency could not confidently predict a
specific biological response (such as an SCI score) for an individual
stream solely from the associated stream measurements of TN or TP
concentrations. 

There may be several reasons why empirical relationships between
field-derived data of nutrient stressor and biological response
variables show a relatively weak correlation.  First, the relationship
between nutrient concentrations and a biological response, such as algal
growth, can be confounded by the presence of other stressors.  For
example, other stressors, such as excessive scour could cause low
benthic invertebrate diversity, as measured by the SCI, even where
nutrients are low.  Excessive scour could also suppress a biological
response (such as chlorophyll a or periphyton biomass) when nutrients
are high.  Another reason for stressor-response relationships with low
correlations is that algal biomass accumulation is difficult to
characterize because dynamic conditions in an individual stream can
allow algae to accumulate and be removed rapidly, which is difficult to
capture with periodic monitoring programs.   

As an alternative to the stressor-response approach, EPA analyzed the TN
and TP concentrations associated with a healthy biological condition in
streams, and examined the statistical distributions of these data in
order to identify an appropriate threshold for providing protection of
aquatic life designated uses.  To derive the instream protection values
under this approach, EPA first assembled the available nutrient
concentrations and biological response data for streams in Florida.  EPA
used FDEP’s data from the IWR and STORET databases and identified
sites where SCI scores were 40 and higher.  EPA further screened these
sites by cross-referencing them with Florida’s CWA section 303(d) list
for Florida and excluded sites with identified nutrient impairments or
dissolved oxygen impairments associated with elevated nutrients.  EPA
grouped the remaining sites (hereafter, biologically healthy sites)
according to its nutrient watershed regions (Panhandle, Bone Valley,
Peninsula, and North Central).  For each nutrient watershed region, EPA
compiled nutrient data (TN and TP concentrations) associated with the
biologically healthy sites, and calculated distributional statistics for
annual average TN and TP concentrations.

The second step in deriving instream protection values was to further
characterize the distribution of TN and TP among biologically healthy
sites.  Specifically, EPA calculated the number of biologically healthy
sites within integer log-scale ranges of TN and TP concentrations, as
well as the cumulative distribution.  These nutrient distributions from
biologically healthy sites in each nutrient watershed region are
represented on a log-scale because concentration data are typically
log-normally distributed.  A log-normal distribution is skewed, with a
mode near the geometric mean rather than the arithmetic mean.  

The third step in deriving instream protection values was to determine
appropriate thresholds from these distributions for providing protection
of aquatic life designated uses.  Selection of a central tendency of the
distribution (i.e., the median or geometric mean of a log-normal
distribution) would imply that half of the biologically healthy sites
are not attaining their uses.  In contrast, an extreme upper end of the
distribution (e.g., the 90th or 95th percentile) may be the most likely
to be heavily influenced by extreme event factors that are not
representative of typically biologically healthy sites.  This might be
the case because the upper tail of the distribution might reflect a high
loading year (landscape and/or atmospheric), and/or lack of nutrient
uptake by algae (in turn due to a myriad of physical and biological
factors like scour, grazing, light limitation, other pollutants).  Thus,
this tail of the distribution may just represent the most nutrient
“tolerant” among the sites.  Another possibility is that these
streams may experience adverse effects from nutrient enrichment that are
not yet reflected in the SCI score.  A reasonable choice for a threshold
is one which lies just above the vast majority of the population of
healthy streams.  This choice is reasonable because it reflects a point
where most biologically healthy sites will still be identified as
attaining uses, but avoids extrapolations into areas of the distribution
characterized by only a few data points (as would be the case for the
90th or 95th percentile).  When a threshold is established as a water
quality criterion, sites well below that threshold might be allowed to
experience an increase in nutrient levels up to the threshold level. 
There is little assurance that biologically healthy sites with nutrient
concentrations well below the 90th or 95th percentile would remain
biologically healthy if nutrient concentrations increased to those
levels because relatively few sites with nutrient concentrations as high
as those at the 90th or 95th percentile are demonstrated to be
biologically healthy.  

he range between the 25th and 75th percentiles, or inter-quartile range,
is a common descriptive statistic used to characterize a distribution of
values.  For example, statistical software packages typically include
the capability to display distributions as “box and whisker” plots,
which very prominently identify the inter-quartile range.  The
inter-quartile range of a log normal distribution spans a smaller range
of values than the inter-quartile range of a distribution of the data
evenly spread across the entire range of values.  This means that the
further a value goes past the 75th percentile of a log normal
distribution, the less representative it is of the majority of data (in
this case, less representative of biologically healthy sites.   Within
the inter-quartile range of a log normal distribution, the slope of the
cumulative frequency distribution will be the greatest.  The 75th
percentile represents a reasonable upper bound of where there is the
greatest confidence that biologically healthy sites will be represented.
 Beyond the inter-quartile range (i.e., below the 25th percentile and
above the 75th percentile), there is a greater chance that measurements
may represent anomalies that would not correspond to long-term healthy
conditions in the majority of streams.  Based on this analysis, EPA
concluded that the 75th percentile represents an appropriate and
well-founded protective threshold derived from a distribution of
nutrient concentrations from biologically healthy sites.  EPA solicits
comment on its analysis of what constitutes a protective threshold.

 (d)  Proposed Criteria:  Duration and Frequency 

Aquatic life water quality criteria contain three components: magnitude,
duration, and frequency.  For the TN and TP numeric criteria for
streams, the derivation of the criterion-magnitude values is described
above and these values are provided in the table in Section III.C(1). 
The criterion-duration of this magnitude is specified in footnote a of
the streams criteria table as an annual geometric mean.  EPA is
proposing two expressions of allowable frequency, both of which are to
be met.  First, EPA proposes a no-more-than-one-in-three-years excursion
frequency for the annual geometric mean criteria for lakes.  Second, EPA
proposes that the long-term arithmetic average of annual geometric means
not to exceed the criterion-magnitude concentration.  EPA anticipates
that Florida will use their standard assessment periods as specified in
Rule 62-303, F.A.C. (Impaired Waters Rule) to implement this second
provision.  These proposed duration and frequency components of the
criteria are consistent with the data set used to derive these criteria,
which applied distributional statistics to measures of annual geometric
mean values from multiple years of record.  EPA has determined that
this frequency of excursions will not result in unacceptable effects on
aquatic life as it will allow the stream ecosystem enough time to
recover from an occasionally elevated year of nutrient loadings.  The
Agency requests comment on these proposed duration and frequency
components of the stream numeric nutrient criteria.

a criterion-frequency expressed as meeting allowable magnitude and
duration as a long-term average only.  EPA further requests comment on
whether an expression of the criteria in terms of an arithmetic average
of annual geometric mean values based on rolling three-year periods of
time would also be protective of the designated use.

 (3)  Request for Comment and Data on Proposed Approach

EPA is soliciting comments on the approaches taken by the Agency to
derive these proposed criteria, the data underlying those approaches,
and the proposed criteria specifically.  EPA is requesting that the
public submit any other scientific data and information that may be
available related to nutrient concentrations and associated biological
responses in Florida’s streams.  EPA is soliciting comment
specifically on the selection of criteria parameters for TN and TP; the
proposed classification of streams into four regions based on aggregated
watersheds; and the conclusion that the proposed criteria for streams
are protective of designated uses and adequately account for the spatial
and temporal variability of nutrients.  In addition, EPA requests
comment on folding the Suwannee River watershed in north central Florida
into the larger Peninsula NWR (i.e., not having a separate North Central
region) or, alternatively, making a smaller North Central region within
Hamilton County alone where the highest phosphorus-rich soils are
located, with the remainder of the North Central becoming part of the
Peninsula Region.

(4)  Alternative Approaches Considered by EPA

During EPA’s review of the available data and information for
derivation of numeric nutrient criteria for Florida’s streams, EPA
also considered an alternative approach for criteria derivation.  EPA is
specifically requesting comment on a modified reference condition
approach called the benchmark distribution approach, as described below.

(a)  Benchmark Distribution Approach 

EPA’s previously published guidance has recommended a variety of
methods to derive numeric nutrient criteria.  One method, the reference
condition approach, relies on the identification of reference waters
that exhibit minimal impacts from anthropogenic disturbance and are
known to support designated uses.  The thresholds of nutrient
concentrations where designated uses are in attainment are calculated
from a distribution of the available associated measurements of ambient
nutrient concentrations at these reference condition sites.

EPA is seeking comment on a modified reference condition approach, which
was developed by FDEP and is referred to as the benchmark distribution
approach.  The benchmark approach relies on least-disturbed sites rather
than true reference, or minimally-impacted, sites.  The benchmark
distribution is a step-wise procedure used to calculate distributional
statistics of TN and TP from identified least-disturbed streams.  

(i)  Identification of Least-Disturbed Streams

FDEP identified benchmark stream sites in the following step-wise manner
1) compiled a list of sites with low landscape development intensity
using FDEP’s Landscape Development Intensity Index, 2) eliminated any
sites on Florida’s CWA section 303(d) list of impaired waters due to
nutrients, as well as certain sites impaired for dissolved oxygen, where
the State determined the dissolved oxygen impairment was caused by
nutrients, 3) eliminated any sites with nitrate concentrations greater
than FDEP’s 0.35 mg/L proposed nitrate-nitrite criterion in order to
reduce the possibility of including sites with far-field human
disturbance from groundwater impacts, 4) eliminated sites known by FDEP
district scientists to be disturbed, 5) eliminated potentially erroneous
data through outlier analysis, 6) verified sites using high resolution
aerial photographs, and 7) verified a random sample of the sites in the
field.

(ii)  Calculation of Benchmark Distribution Approach and Selection of
Percentiles from the Benchmark Distribution

FDEP selected either the 75th or 90th percentile of the benchmark
distribution approach from FDEP’s proposed nutrient regions (75th
percentile - Bone Valley; 90th percentile - Panhandle, North Central,
Northeast, and Peninsula).  FDEP’s rationale for selecting either the
75th or 90th percentiles was based on the degree of certainty regarding
the benchmark sites reflecting least-disturbed conditions and a
probability (10% for the 90th percentile) of falsely identifying a
least-disturbed site as being impaired for nutrients.  

With this approach, the distribution of available annual geometric means
of nutrient concentrations for the benchmark sites within the regional
classes of streams is calculated.  To compute the numeric criteria for
the causal variables, TN, and TP, EPA is seeking comment on whether the
75th or 90th percentile of the benchmark distribution for each nutrient
stream region should be selected.  As mentioned above, the rationale for
selecting either the 75th or 90th percentiles is based on the degree of
certainty regarding the benchmark sites reflecting least-disturbed
conditions and a probability of falsely identifying a least-disturbed
site as being impaired for nutrients or vice-versa.  In cases where
data are more limited for a given nutrient region (i.e., in the Bone
Valley there were only four sites), the 75th percentile may be more
appropriate because the 90th percentile may not be sufficiently robust
(ie, may be highly sensitive to a few data points).  In other cases, the
90th percentile may be more appropriate when there is a more extensive
data set.  For further information, please refer to EPA’s TSD for
Florida’s Inland Waters, Chapter 2:  Methodology for Deriving U.S.
EPA’s Proposed Criteria for Streams.

In evaluating whether to propose this approach, EPA determined that a
considerable amount of uncertainty remained whether this approach would
result in a list of benchmark sites that represented truly
least-disturbed conditions.  Specifically, EPA is concerned that
nutrient concentrations at these sites may reflect anthropogenic sources
(e.g., sources more than 100 meters away from and/or 10 kms upstream of
the segment), even if the sites appear least-disturbed on a local basis.
 EPA is particularly concerned that several benchmark sites in the FDEP
dataset appear to have a high potential to be affected by fertilizations
associated with forestry activities.  FDEP provided an analysis in which
FDEP concluded that this is not likely.  EPA solicits comment on this
issue and more generally on whether the benchmark sites identified by
FDEP in its July 2009 proposal are an appropriate set of least-disturbed
sites on which to base the criteria calculations.

 (5)  Request for Comment and Data on Alternative Approach

EPA is soliciting comment on the alternative to deriving numeric
nutrient criteria for Florida’s streams as described in Section
III.C(4).    

(6)  Protection of Downstream Lakes and Estuaries

Two key objectives of WQS are: first, to protect the immediate water
body to which a criterion initially applies and, second, to ensure that
criteria provide for protection of downstream WQS affected by flow of
pollutants from the upstream water body.   See 40 CFR 131.11 and
131.10(b).  EPA WQS regulations reflect the importance of protecting
downstream waters by requiring that upstream WQS “provide for the
attainment and maintenance of the water quality standards of downstream
waters.”  40 CFR 131.10(b).  Thus, in developing numeric nutrient
criteria for Florida, EPA considered both instream aquatic conditions
and downstream aquatic ecosystem needs.  In addressing the issue of how,
if at all, instream criteria values need to be adjusted to assure
attainment of downstream standards, EPA necessarily examined the WQS for
downstream lakes and estuaries.  For lakes, this analysis starts with
the numeric nutrient criteria proposed in this notice.  For estuaries,
this notice proposes an analytical approach to determine the loadings
that a particular estuary can receive and still assure attainment and
maintenance of the State's WQS for the estuary (i.e., a protective
load).  An approach is then proposed for translating those downstream
loading values into criteria levels in the contributing watershed stream
reaches in a manner that ensures that the protective downstream loadings
are not exceeded.

In connection with both lakes and estuaries, EPA fully recognizes that
there are a range of important technical questions and related
significant issues raised by this proposed approach for developing
instream water quality criteria that are protective of downstream
designated uses.  With regard, in particular, to the protection of
estuaries, the Agency is working closely with FDEP to derive estuarine
numeric nutrient criteria for proposal and publication in 2011.  Even
though estuarine numeric nutrient criteria will be developed in 2011,
there is already a substantial body of information, science, and
analysis that presently exists that should be considered in determining
flowing water criteria that are protective of downstream water quality. 
 

The substantial data, peer-reviewed methodologies, and extensive
scientific analyses available to and conducted by the Agency to date
indicate that numeric nutrient criteria for estuaries, when proposed and
finalized in 2011, may result in the need for more stringent rivers and
streams criteria to ensure protection of downstream water quality,
particularly for the nitrogen component of nutrient pollution. 
Therefore, considering the numerous requests for the Agency to share its
analysis and scientific and technical conclusions at the earliest
possible opportunity to allow for full review and comment, EPA is
including downstream protection values for TN as proposed criteria for
rivers and streams to protect the State's estuaries in this notice.  

As described in more detail below and in EPA’s TSD for Florida’s
Inland Waters accompanying this notice, these proposed nitrogen
downstream protection values are based on substantial data, thorough
scientific analysis, and extensive technical evaluation.  However, EPA
recognizes that additional data and analysis may be available for
particular estuaries to help inform what water quality criteria are
necessary to protect these waters.  EPA also recognizes that substantial
site-specific work (including some very sophisticated analyses in the
context of certain TMDLs) has been completed for a number of these
estuaries.  This notice and the proposed downstream protection values
are not intended to address or be interpreted as calling into question
the utility and protectiveness of these site-specific analyses.  Rather,
the proposed values represent the output of a systematic and scientific
approach that may be generally applicable to all flowing waters in
Florida that terminate in estuaries for the purpose of ensuring the
protection of downstream estuaries.  EPA is interested in obtaining
feedback at this time on this systematic and scientific approach.  The
Agency further recognizes that the proposed values in this notice will
need to be considered in the context of the Agency's numeric nutrient
criteria for estuaries scheduled for proposal in January of 2011.  At
this time, EPA plans to finalize any necessary downstream protection
values for nitrogen in flowing waters as part of the second phase of
this rulemaking process in coordination with the proposal and
finalization of numeric criteria for estuarine and coastal waters in
2011.  However, if comments, data and analyses submitted as a result of
this proposal support finalizing such values sooner, by October 2010,
EPA may choose to proceed in this manner.  To facilitate this process,
EPA requests comments and welcomes thorough evaluation on the need for
and the technical and scientific basis of these proposed downstream
protection values as part of the broader comment and evaluation process
that this proposal initiates.

EPA believes that a detailed consideration and related proposed approach
to address protection of downstream water quality in this proposal is
necessary for several reasons, including 1) water quality standards are
required to protect downstream uses under Federal regulations at 40 CFR
131.10(b), meaning also for prevention of impairment; 2) it may be a 
relevant consideration in the development of any TMDLs, NPDES permits,
and Florida BMAPs that the State completes in the interim period between
the final rule for Florida lakes and flowing waters in October 2010 and
a final rule for Florida estuarine and coastal waters in October of
2011; and 3) perhaps most importantly, it is essential for informing and
supporting a transparent and engaged public consideration, evaluation,
and discussion on the question of what existing information, tools, and
analyses suggest regarding the need to ensure protection of downstream
waters. The Agency continues to emphasize its interest in and request
for additional information, further analysis, and any alternative
technically-based approaches that may be available to address protection
of downstream water quality.  EPA also reiterates its commitment to a
full evaluation of all comments received and notes the ability to issue
a NODA to allow a full public review should significant new additional
information and analysis become available as part of the comment period.

In deriving criteria to protect designated uses, as noted above, Federal
WQS regulations established to implement the CWA provide WQS must
provide for the protection of designated uses in downstream waters.  In
the case of deriving numeric nutrient criteria for streams in Florida,
EPA’s analyses reflected in this notice indicate that the proposed
criteria values for instream protection of streams may not fully protect
downstream lakes and downstream estuaries.  EPA’s proposed criteria
for lakes are, in some cases, more stringent than the proposed criteria
for streams that flow into the lakes.  For estuaries, EPA’s analyses
of protective loads delivered to a specific estuary, and the
corresponding expected concentration values for streams that flow into
that estuary, indicate the proposed criteria for instream protection may
not always be sufficient to provide for the attainment and maintenance
of the estuarine WQS.  For more detailed information, please consult
EPA’s TSD for Florida’s Inland Waters, Chapter 2:  Methodology for
Deriving U.S. EPA’s Proposed Criteria for Streams.  

To address each of these issues, EPA is proposing first, for lakes, an
equation that allows for input of lake characteristics to determine the
concentration in flowing streams that is needed to attain and maintain
the receiving lake’s designated use and protective criteria.  Second,
for estuaries, EPA is proposing an approach for identifying the total
nutrient loads a particular estuary can receive and still attain and
maintain the State’s designated use for the water body.  Third, also
for estuaries, the Agency is proposing a methodology to derive
protective concentration values for the instream criteria where
necessary to assure that downstream estuarine loads are not exceeded. 
The following sections provide a more detailed explanation of the
proposed downstream protective approach for lakes and then for
estuaries.  

(a)  Downstream Protection of Lakes 

EPA is proposing an equation to relate a lake TP concentration criterion
to the concentration needed to be met in incoming streams to support the
lake criterion.  EPA proposes to apply the resulting stream
concentration as the applicable criterion for all stream segments
upstream of the lake.  EPA used a mathematical modeling approach to
derive this equation, with allowable input of lake-specific
characteristics, to calculate protective criteria necessary to assure
attainment and maintenance of the numeric lake nutrient criteria in this
proposal.  More specifically, EPA started with a phosphorus loading
model equation first developed by Vollenweider.  EPA assumed that
rainfall exceeds evaporation in Florida lakes and that all external
phosphorus loading comes from streams.  EPA considers the first
assumption reasonable given the rainfall frequency and volume in
Florida.  The second assumption is reasonable to the extent that surface
runoff contributions are far greater than groundwater or atmospheric
sources of TP in Florida lakes.  EPA requests comment on both these
assumptions.  After expressing these assumptions in terms of the
mathematical relationships among loading rates, stream flow, and lake
and stream concentrations, EPA derived the following equation to relate
a protective lake criterion to a corresponding protective stream
concentration:

 

where

[TP]S is the total phosphorus (TP) downstream lake protection value,
mg/L

[TP]L is applicable TP lake criterion, mg/L

cf is the fraction of inflow due to all stream flow, 0 ( cf ( 1

w is lake’s hydraulic retention time (water volume divided by
annual flow rate)

  expresses the net phosphorus loss from the water column (e.g. via
settling of sediment-sorbed phosphorus) as a function of the lake’s
retention time

This model equation requires input of two lake-specific characteristics:
the fraction of inflow due to stream flow and the hydraulic retention
time.  Water in a lake can come from a combination of groundwater
sources, rainfall, and streams that flow into it.  Using the model
equation above, the calculated stream TP criterion to protect a
downstream lake will be more stringent for lakes where the portion of
its volume coming from streams flowing into it is the greatest.  In
addition, the calculated stream TP criterion to protect a downstream
lake will be more stringent for lakes with short hydraulic retention
times (how long water stays in a lake) because the longer the water
stays in the lake, the more phosphorus will settle out in the underlying
lake sediment. 

Because lake-specific input values may not always be readily available,
EPA is providing preset values for percent contribution from stream flow
and hydraulic retention time.  In Florida lakes, rainfall and
groundwater sources tend to contribute a large portion of the total
volume of lake water.  In fact, only about 20% of the more than 7,000
Florida lakes have a stream flowing into them, with the rest entirely
comprised of groundwater and rainwater sources.  EPA evaluated
representative values for percent contribution from stream flow and
hydraulic retention time, and selected 50% stream flow contribution and
0.2 years (about two and a half months) retention time as realistic and
representative preset values to provide a protective outcome for Florida
lakes, in the absence of site-specific data.  Using these preset values,
streams that flow into colored lakes would have a TP criterion of 0.12
mg/L, and streams that flow into clear, alkaline lakes would have a TP
criterion of 0.073 mg/L, with respect to downstream lake protection.  In
the Peninsula NWR, this compares to a 0.107 mg/L TP stream criterion
protective of instream designated uses.  EPA’s proposed rule does
offer the flexibility to use site-specific inputs to the Vollenweider
equation for fraction of inflow from streamflow and hydraulic retention
time, as long as data supporting such inputs are sufficiently robust and
well-documented.

EPA carefully evaluated use of a settling/loss term for phosphorus in
the model equation.  Florida lakes tend to be shallow, and internal
loadings to the lake water (e.g. from re-suspension of settled
phosphorus after storms that stir up lake sediment) may be substantial. 
A more detailed model might be able to simulate this phenomenon
mechanistically, but would likely require substantial site-specific data
for calibration.  For this reason, EPA chose to use the model
formulation above.  EPA considered a simpler alternative to exclude the
settling/loss term from the above equation, or even to reverse the sign
on the settling/loss term so that it becomes a net source term, perhaps
with the inclusion of a default multiplier.  However, EPA did not have
sufficient information to conclude that such a conservative approach was
necessary as a general application to all Florida lakes.  EPA remains
open and receptive to comment on these alternatives or other technically
sound and protective approaches.  EPA’s supporting analyses and
detailed information on this downstream lake protection methodology are
provided in the accompanying TSD for Florida’s Inland Waters, Chapter
2:  Methodology for Deriving U.S. EPA’s Proposed Criteria for Streams.

The same processes that occur in lakes and affect lake water phosphorus
concentration may also occur in streams that feed lakes and affect
stream water phosphorus concentrations.  These processes include
sorption to stream bed sediments, uptake into biota, and release into
the water column from decaying vegetation.  EPA took into consideration
these processes when deciding whether it would be appropriate to add a
term to the model equation to account for phosphorus loss or uptake
within the streams in deriving stream criteria for downstream lake
protection.  However, the net result of these processes is nutrient
spiraling, whereby nutrients released upstream gradually propagate
downstream at a rate slower than that of the moving water, and cycle
into and out of the food chain in the process.  Over the short term, the
result may be water concentrations that decrease in the downstream
direction.  However, unlike for nitrogen, there are no long-term
phosphorus net removal processes at work in streams.  Phosphorus
adsorbed to sediment particles is eventually carried downstream with the
sediment, and phosphorus taken up by plants is eventually returned to
the flowing water.  Over the long term, upstream phosphorus inputs are
in equilibrium with downstream phosphorus outputs.  Recognizing this
feature of stream systems and the conservative nature of phosphorus in
aquatic environments, EPA concluded that it was not appropriate to
include a phosphorus loss term that would apply to streams as they
progress toward a downstream lake.  For further information, please
refer to EPA’s TSD for Florida’s Inland Waters, Chapter 2: 
Methodology for Deriving U.S. EPA’s Proposed Criteria for Streams.

  in the equation above either equal to zero or with the plus sign
switched to a minus sign).  EPA also requests comment on whether and how
to address direct surface runoff into the lake.  Where this input is
substantial and land use around the lake indicates that phosphorus input
is likely, EPA believes it may be appropriate to include this water
volume contribution as part of the fraction of inflow considered to be
streamflow to be protective and consistent with the assumption of no
loading from sources other than streamflow.  EPA specifically requests
comment on use of the Land Development Index (LDI) as an indicator of
how to treat this inflow, examination of regional groundwater phosphorus
levels to see if a zero TP input from this source is appropriate, and
potential development of regionally-specific preset values as inputs to
the equation.  In addition, EPA requests comment on the potential to
develop a corollary approach for nitrogen.  

EPA is open to alternative technically-supported approaches based on
best available data that offer the ability to address lake-specific
circumstances.  The Agency recognizes that more specific information may
be readily available for individual lakes which could allow the use of
alternative approaches such as the BATHTUB model.  The Agency welcomes
comment and technical analysis on the availability and application of
these models.  In this regard, EPA requests comment on whether there
should be a specific allowance for use of alternative lake-specific
models where demonstrated to be protective and scientifically defensible
based upon readily and currently available data, and whether use of such
alternatives should best be facilitated through use of the SSAC
procedure described in Section V.C. 

(b)  Downstream Protection of Estuaries

(i)  Overview

EPA is proposing a methodology for calculation of applicable criteria
for streams that flow into estuaries and provide for their protection. 
The proposed methodology would allow the State to utilize either 1)
EPA's downstream protection values (DPVs), or 2) the EPA DPV methodology
utilizing EPA's estimates of protective loading to estuaries but with
the load re-distributed among the tributaries to each estuary, or 3) an
alternative quantitative methodology, based on scientifically defensible
approaches, to derive and quantify the protective load to each estuary
and the associated protective stream concentrations.  The DPV
methodology with a re-distributed load may be used if the State provides
public notice and opportunity for comment.  To use an alternative
technical approach, based on scientifically defensible methods to derive
and quantify the protective load to each estuary and the associated
protective stream concentrations, the State must go through the process
for a Federal SSAC as described in Section V.C.   In some cases, the
substantial and sophisticated analyses and scientific effort already
completed in the context of the TMDL process may provide sufficient
support for a SSAC.  In such circumstances, EPA encourages FDEP to
submit these through the SSAC process and EPA looks forward to working
with FDEP in this process.  

EPA's approach to developing nutrient criteria for streams to protect
downstream estuaries in Florida involves two separate steps.  The first
step is determining the average annual nutrient load that can be
delivered to an estuary without impairing designated uses.  This is the
protective load.  The second step is determining nutrient concentrations
throughout the network of streams and rivers that discharge into an
estuary that, if achieved, are expected to result in nutrient loading to
estuaries that do not exceed the protective load.  These concentrations,
called "downstream protection values" or DPVs, depend on the protective
load for the receiving estuary and account for nutrient losses within
streams from natural biological processes.  In this way, higher DPVs may
be appropriate in stream reaches where a significant fraction of either
TN or TP is permanently removed within the reach before delivery to
downstream receiving waters. EPA's approach utilizes results obtained
from a watershed modeling approach called SPAtially Referenced
Regressions on Watershed attributes, or SPARROW.  The specific model
that was used is the South Atlantic, Gulf and Tennessee (SAGT) regional
SPARROW model.  EPA selected this model because it provided the
information that was needed at the appropriate temporal and spatial
scales and it applies to all waters that flow to Florida’s estuaries. 
SPARROW was developed by the United States Geological Survey (USGS) and
has been reviewed, published, updated and widely applied over the last
two decades.  It has been used to address a variety of scientific
applications, including management and regulatory applications.  In
order to fully understand EPA's methodology for developing DPVs, it is
useful to understand how the approach utilizes results from SPARROW, as
well some aspects of how SPARROW works.

 

The remaining discussion focuses on TN, for which EPA has already
computed DPVs.  The approach for computing DPVs for TP from estimates of
the protective TP load is expected to be essentially the same as for TN.
 However, there is some question as to whether the same approach used to
determine the protective TN load will also apply to TP.  EPA requests
comment on this issue.

(ii)  EPA Approach to Estimating Protective Nitrogen Loads for Estuaries

The first step in EPA’s approach is to narrow the range of possible
values.  The protective TN load is expected to vary widely among Florida
estuaries because they differ significantly in their size and physical
and biological attributes.  For example, well flushed estuaries are able
to receive higher TN loading without adverse effect compared to poorly
flushed estuaries.  EPA recognized that it may be possible to narrow
this initially very broad range of possible protective loads using one
consistent approach, and then consider whether additional information
might enable a further reduction in uncertainty.  EPA is soliciting
credible scientific evidence that may improve these estimates and
further reduce uncertainty surrounding the proposed protective loads. 
The most useful evidence would provide a scientific rationale, an
alternative estimate of the protective load, and an associated
confidence interval for the estimate.  For further information, please
refer to EPA’s TSD for Florida’s Inland Waters, Chapter 2: 
Methodology for Deriving U.S. EPA’s Proposed Criteria for Streams.

EPA first narrowed the range of possible protective loads by
establishing an estimate of current loading as an upper bound.  Most of
Florida's estuaries are listed as impaired to some extent by nutrients
or nutrient-related causes.  Florida's 1998 CWA section 303(d) verified
list of impaired waters under the Impaired Waters Rule (FAC 62-303)
identify many estuaries or estuary segments that are impaired by
nutrients, chlorophyll a, or low dissolved oxygen.  Many or most
estuaries have reduced water clarity and substantial loss of seagrass
habitats.  The National Estuarine Eutrophication Assessment reports that
current conditions are poor for many estuaries in Florida.  This
information implies that current levels of TN loading are at least an
upper limit for the protective load and likely exceed the protective
load in many estuaries.  

hile nitrogen loads have been estimated from monitored gauge stations in
many stream and rivers, a large fraction of Florida streams and
watersheds are not gauged and thus load estimates were not previously
available.  An approach was needed to spatially extrapolate the
available measurements of loading to obtain estimates of loading for all
streams including those in unmonitored watersheds or portions of
watersheds. The SAGT SPARROW model provided these estimates for all
Florida estuarine watersheds.  The SPARROW modeling approach utilizes a
multiple regression equation to describe the relationship between
watershed attributes (i.e., the predictors) and measured instream
nutrient loads (i.e., the responses).  The statistical methods
incorporated into SPARROW help explain instream nutrient water quality
data (i.e., the mass flux of nitrogen) as a function of upstream sources
and watershed attributes.  The SAGT-SPARROW model utilized period of
record monitored streamflow and nutrient water quality data from Florida
and across the SAGT region for load estimation.  SAGT-SPARROW also used
extensive geospatial data sets describing topography, land-use, climate,
and soil characteristics, nitrogen loading for point sources in Florida
obtained from EPA's permit compliance system, and estimates of nitrogen
in fertilizer and manure from county-level fertilizer sales, census of
agriculture, and population estimates.  TN load estimates explain 96% of
the variation in observed loads from monitoring sites across the region
with no spatial bias at Florida sites.  A more thorough description of
the SAGT-SPARROW model, the data sources, and analyses are found in the
EPA TSD for Florida’s Inland Waters and in USGS publications.

PA recognizes that some watershed models define more types of sources,
according to their modeling objectives; however, it is important to
recognize that these are source classes, not sources, and that 100% of
the measured loading is accounted for explicitly or implicitly by
SPARROW in terms of these source classes.  

The class termed "atmospheric" reflects all loading that cannot be
empirically attributed to causal variables associated with the other
classes.  EPA used the estimate for this class of loading as the
background TN load.  EPA recognizes that the SPARROW-estimated
“atmospheric” load includes anthropogenic contributions associated
with regional-scale nitrogen emissions and does not represent
pre-industrial or true “natural” background loading.  The
“atmospheric” source term from SPARROW is also not equal to
atmospheric nitrogen deposition as measured by the National Atmospheric
Deposition Program (NADP).  To properly interpret the TN load attributed
to the “atmospheric” source term in SPARROW, it is useful to
recognize that SPARROW is a nonlinear regression model that seeks to
explain measured TN loads in streams and rivers in terms of a series of
explanatory variables.  The atmospheric term is in all cases less, and
often much less, than the measured deposition because not all the
nitrogen deposited to the landscape is transported to streams, and not
all of the nitrogen transported in streams reaches estuaries.  The
atmospheric source term from SPARROW excludes all the loading associated
with both local anthropogenic nitrogen sources and factors contributing
to increased transport of nitrogen from all sources (e.g., impervious
surfaces).  Therefore, EPA expects that reasonable values for the
protective TN load are not likely to be less than these values.

The protective TN load should be less than the current load and greater
than the background load.  Although this recognition may appear to be
trivial, it is important.  EPA estimates that TN loads to estuaries
across Florida vary approximately 25-fold (~2 to 50 grams of nitrogen
per square meter of estuary area).  However, the ratio of the current
load to the background load varies only between 1.7 and 5; for most
estuaries, the range is between 2 and 4.  Alternatively stated, current
TN loads, which include local anthropogenic nitrogen sources, are two to
four-fold higher than the background loads which do not include those
sources.  Thus, for any specific estuary, there is a relatively narrow
range between the upper and lower bounds of potential protective loads. 

EPA acknowledges that not all the TN entering estuaries comes directly
from the streams within its watershed.  In some estuaries, direct
atmospheric nitrogen deposition to the estuary surface may be an
important source of TN loading to the estuary.  Similarly, point sources
such as industrial or wastewater treatment plant discharges directly to
the estuary can be significant.  In general, these sources are most
significant when the ratio of watershed area to estuary area is
relatively small compared to other estuaries (e.g., St. Andrew Bay,
Sarasota Bay).  In a few cases in Florida, point source loads directly
to the estuary account for a large fraction of the aggregate load from
all sources. 	

As a second step, EPA sought to further reduce the range of possible
protective loading values by considering additional evidence.  One line
of evidence EPA considered is previous estimates of protective loads. 
These have been developed as part of TMDLs for Florida estuaries or as
part of Florida's Pollutant Load Reduction Goal or PLRG program.  The
scientific approaches utilized for TMDLs and PLRGs vary from simple to
sophisticated and have recommended TN loading reductions between 3% and
63%, with a median of 38%.  Higher reductions are typically associated
with portions of estuaries currently receiving higher anthropogenic
loading.  Unfortunately, these analyses have not been completed for all
of Florida's estuaries.  Steward and Lowe (2009) showed that the TN
loading limits suggested by TMDLs and PLRGs for a variety of aquatic
ecosystems in Florida, including estuaries, could be statistically
related to water residence time for the receiving water.  EPA evaluated
these relationships as an additional line of evidence for estimating
protective TN loads for estuaries.  EPA found these relationships to
confirm in most cases, but not all, that the loading limits were likely
between the bounds EPA previously established using SPARROW.  However,
the limits of uncertainty associated with the relationship were nearly
as large as those already established.  Nonetheless, the models provide
additional support for EPA’s estimates of protective estuary loads,
but no further refinement of the estimates.

Another approach to considering existing TMDLs and PLRGs is to consider
directly the loading rate reductions recommended from those efforts, the
median of which is 38% in Florida.  This percent TN reduction is similar
to the scientific consensus for several well-studied coastal systems
elsewhere (e.g., Chesapeake Bay, northern Gulf of Mexico) which have
been subjected to increased TN loads from known anthropogenic sources. 
EPA recognizes that the magnitude of anthropogenic TN loads varies
across Florida estuaries and that applying a uniform percent reduction
across all estuaries does not account for the variable extent of
anthropogenic loads and could lead to estimates below background load. 
An alternative approach is to assume that the appropriate loading
reduction is proportional to the magnitude of anthropogenic enrichment. 
Thus, EPA suggests that protective TN loading may be estimated by
assuming that the anthropogenic component of TN loading should be
reduced by a constant fraction.

As a result, EPA computed the protective TN load by reducing the current
TN load by one half of the anthropogenic contribution to that load. 
EPA's protective load estimates are on average 25% less than current TN
loading (range=5 to 40%), consistent with most TMDLs and PLRGs for
Florida estuaries.

EPA developed protective TN loads for 16 estuarine water bodies in
Florida for the purpose of computing DPVs for streams that are
protective of uses in the estuarine receiving waters.  EPA did not
develop loading targets for the seven estuarine water bodies in south
Florida (Caloosahatchee, St. Lucie, Biscayne Bay, Florida Bay, North and
South Ten Thousand Islands, and Rookery Bay), because requisite
information related to TN loading from the highly managed canals and
waterways cannot be derived from SAGT-SPARROW and were not available
otherwise, and three in central Florida (coastal drainage areas of the
Withlacoochee River, Crystal-Pithlachascotee River and Daytona-St.
Augustine) because EPA is still evaluating appropriate protective loads
and the flows necessary to derive DPVs.   

PA notes that some stakeholders, including FDEP staff, have raised
concerns about the suitability of the SAGT SPARROW to address downstream
protection of estuaries and have suggested alternative models and
approaches that have been applied for several of Florida's larger
estuaries and their watersheds.  These concerns include known
limitations of the SPARROW model, particularly related to inadequate
resolution of complex hydrology in several parts of the State.  EPA also
recognizes this limitation and as a result, has not used SAGT SPARROW to
propose protective loads and associated downstream protection values for
ten estuaries and their watersheds in Florida.  EPA acknowledges that
other approaches and models may also provide defensible estimates of
protective loads.  

Among the technical concerns that stakeholders including FDEP staff have
raised are that: 1) SPARROW is useful for general pattern, but the large
scale calibration lead to large errors for specific areas, 2) SPARROW
only utilizes four source inputs, and 3) SPARROW was calibrated to only
one year’s worth of data.  As presented in the above sections, but to
briefly reiterate here: 1) SPARROW is calibrated across a larger area,
but it utilizes a large amount of Florida site-specific data and it
explains 96% of the variation in observed loads from monitoring sites,
2) SPARROW accounts for all sources, but groups them into four general
categories, and 3) SPARROW uses available data from the 1975-2004 period
at monitored sites.  This last concern may be confused with the
technical procedure of presenting loading estimates as “detrended to
2002”.  This procedure accounts for long-term, inter-annual
variability to ensure that long-term conditions and trends are
represented.  The year 2002 was selected as a baseline because it has
the best available land use/land cover information available, but the
loading estimates, in fact, represent a long-term condition
representative of many years of record.  EPA encourages technical
reviewers to consult with the technical references cited in this section
for the complete explanations of technical procedures.

EPA requests comment on its use of the SPARROW model to derive
protective loads for downstream estuaries, as well as data and analyses
that would support alternate methods of deriving downstream loads, or
alternate methods of ensuring protection of designated uses in
estuaries.  For estuaries where sophisticated scientific analyses have
been completed, relying on ample site-specific data to derive protective
loads in the context of TMDLs, EPA encourages FDEP to submit resulting
alternative DPVs under the SSAC process.

 (iii)  Computing Downstream Protection Values (DPVs)

Once an estimate of protective TN loads is derived, EPA developed a
methodology for computing DPVs, for streams that, if achieved, are
expected to result in an average TN loading rate that does not exceed
the protective load.  EPA’s methodology, which is used as the
narrative translator, allows for the fraction of the protective TN
loading contributed from each tributary within the watershed of an
estuary to be determined by the fraction of the total freshwater flow
contributed by that tributary.  The DPV is specified as an average TN
concentration, which is computed by dividing the protective TN load by
the aggregate average freshwater inflow from the watershed.  This
approach results in the same DPV for each stream or river reach that
terminates into a given estuary.

EPA’s methodology accounts for instream losses of TN.  EPA recognizes
that not all the TN transported within a stream network will ultimately
reach estuaries.  Rather, some TN is permanently lost from streams. 
This is not the same as reversible transformations of TN, such as algal
uptake.  Losses of TN are primarily associated with bacterially-mediated
processes in stream sediments that convert biologically available
nitrogen into inert N2 gas, which enters the atmosphere (a process
called denitrification).  This occurs more rapidly in shallow streams
and at almost negligible rates in deeper streams and rivers.  EPA refers
to the fraction of nitrogen transported in streams that ultimately
reaches estuaries as the "fraction delivered.”  Estimates of the
fraction delivered in Florida are less than 50% in streams very distant
from the coast, but is between 80 and 100% in approximately half the
stream reaches in Florida's estuarine watersheds.

stimates of instream losses are modeled in SPARROW using a first-order
decay rate as a function of time-of-travel in the reach.  The inverse
exponential relationship is consistent with scientific understanding
that nitrogen losses decrease with increasing stream size and with
results from experimental reach-scale studies using a variety of
methods.  EPA recognizes that stream attributes other than reach
time-of-travel or size may influence instream loss rates and though the
SPARROW model did not include these, the lack of spatial bias in model
residuals suggests that inclusion of other potential subregional-scale
or State-wide stream attributes may not improve modeled instream loss
estimates.  

EPA developed and applied this methodology to compute DPVs for every
stream reach in each of 16 estuarine watersheds starting with
estuarine-specific estimates of the protective load.  These estuarine
watersheds align with the Nutrient Watershed Regions (NWR) used to
derive instream protection values (IPVs).  It is important to note that
the scale at which protective loads and DPVs were derived is smaller
than for IPVs (i.e., 16 estuarine watersheds vs. 4 nutrient watershed
regions).  EPA’s recognition that some fraction of nitrogen
transported in streams is retained or assimilated before reaching
estuarine waters help ensure that the DPVs are not overprotective of
downstream use in any particular estuary.  

In determining TN DPVs, EPA considered the contribution of TN inputs
from wastewater discharged in shoreline catchments directly to the
estuary.  EPA found these point source inputs to be significant (>5% of
total loading) in three (St. Andrew’s Bay, St. Marys, St. John’s) of
the 16 estuaries.  However, for the purpose of computing stream reach
DPVs for a given estuarine watershed, EPA considered only those TN loads
delivered from the estuarine watershed stream network and did not
include TN inputs from wastewater discharged in shoreline catchments
directly to an estuary because these loads do not originate from
upstream sources.  However, point sources loads directly to the estuary
would need to be considered in developing TMDLs based on
estuary-specific criteria.  

EPA's computation of DPVs using estimates of protective loading for each
estuary and the fraction-delivered to estuaries is shown by equation
(1): 

 ,							(1)

where the terms are defined as follows for a specific or ( ith ) stream
reach:

 		maximum flow-averaged nutrient concentration for a specific (the ith
) stream reach consistent with downstream use protection (i.e., the DPV)

 		fraction of all loading to the estuary that comes from the stream
network resolved by SPARROW

 	protective loading rate for the estuary, from all sources

 	combined average freshwater discharged into the estuary from the
portion of the watershed resolved by the SPARROW stream network

 		fraction of the flux at the downstream node of the specific
(ith)reach that is transported through the stream network and ultimately
delivered to estuarine receiving waters (i.e. Fraction Delivered).

Note that the quantity kLest is equal to the loading to the estuary from
sources resolved by SPARROW.  For the purposes of practical
implementation, EPA classified each stream water body (i.e., Water Body
Identification or “WBID” using the FDEP term) according to the
estuarine receiving water and one of six categories based on the
fraction of TN delivered (0 to 50%, 51-60%,  61-70%, 71-80%, 81-90%, and
91-100%).  For each category, the upper end of the range was utilized to
compute the applicable DPV for streams in the category, resulting in a
value that will be protective.  This approach reduces the number of
unique DPVs from thousands to less than 100.  Because the stream network
utilized by the SAGT-SPARROW watershed model (ERF1) does not recognize
all of the smaller streams in Florida (i.e., it is on a larger scale),
EPA mapped WBIDs to the applicable watershed-scale unit, or
“incremental watersheds,” of the ERF1 reaches, assigning to each
WBID the fraction of TN delivered estimated for the ERF1 reach whose
incremental watershed includes the WBID.  Where the WBID includes
portions of the incremental watersheds of more than one ERF1 reach, EPA
computed a weighted-average based on the proportion of WBID area in the
watershed of each ERF1 reach.  

iven an even distribution of reaches within each 10% interval, EPA’s
“binning” approach to the fraction-delivered estimates results in a
5% to 10% margin of safety for the average reach in each range (closer
to 10% for the lower fraction-delivered ranges).  Potentially larger
margins are possible within the 0 to 50% range, where the fraction
delivered might be 20%, but the DPV would be computed assuming a
fraction delivered of 50%.  However, only one watershed in Florida for
which EPA is proposing DPVs, the St. Johns River, has a substantial
number of reaches estimated to have less than 50% TN delivered to
estuarine waters.  The SAGT-SPARROW watershed model estimates that 17%
of the stream reaches in the St. Johns watershed are in this category,
with about half the reaches delivering nearly 50% of TN and a
substantial number delivering only 20% of TN.  Given EPA’s DPV for
terminal reaches in the St. Johns watershed, however, the DPV for
reaches with a fraction delivered less than 50% will be higher than the
IPV, and therefore, will not apply.  EPA requests comment on the binning
approach for calculating DPVs, which allows for a relatively simple
table of DPVs to be presented as compared to using the actual estimate
of fraction TN delivered to calculate a DPV unique to each WBID using
formula (1), above.

At this time, EPA has not calculated protective TP loads for Florida’s
estuaries or DPVs for TP.  However, advances in the application of
regional watershed models, such as SPARROW, that address the sources and
terrestrial and aquatic processes that influence the supply and
transport of TP in the watershed and delivery to estuaries are currently
in advanced stages of development.  EPA anticipates obtaining the
necessary data and information to compute TP loads for the estuarine
water bodies in Florida in 2010 and could make this additional
information available by issuing a supplemental Federal Register Notice
of Data Availability (NODA), which would also be posted in the public
docket for this proposed rule.  EPA intends to derive proposed
protective loads and DPVs for TP using an analogous approach as used for
TN DPVs.  EPA expects the approach will recognize that TP, like TN, is
essential for estuarine processes but in excess will adversely impact
aquatic life uses.  

(iv)  EPA Downstream Protection Values (DPVs)

The following criteria tables and corresponding DPVs for a given stream
reach category have been geo-referenced to specific WBIDs which are
managed by FDEP as the principal assessment unit for Florida’s surface
waters.  To see where the criteria are geographically applicable, refer
to EPA’s TSD for Florida’s Inland Waters, Appendix B-18: In-Stream
and Downstream Protection Value (IPV/DPV) Tables with DPV Geo-Reference
Table to Florida WBIDs.

Perdido Bay WatershedPH (EDA Code1: G140x)

Protective TN Load for the Estuary2: 847,520 kg y-1

Protective TP Load for the Estuary3: TBD

River/Stream Reach Category - 

Percent Delivered to Estuary4	TN (mg L-1)	TP (mg L-1)

	TN IPV5	TN DPV6	TP IPV7	TP DPV8

Less than 50%	NR	NR	0.043	TBD

50.1 – 60.0%	NR	NR	0.043	TBD

60.1 – 70.0%	NR	NR	0.043	TBD

70.1 – 80.0%	NR	NR	0.043	TBD

80.1 – 90.0%	0.824	0.34	0.043	TBD

90.1 – 100%	0.824	0.30	0.043	TBD



Pensacola Bay WatershedPH (EDA Code1: G130x)

Protective TN Load for the Estuary2: 4,388,478 kg y-1

Protective TP Load for the Estuary3: TBD

River/Stream Reach Category - 

Percent Delivered to Estuary4	TN (mg L-1)	TP (mg L-1)

	TN IPV5	TN DPV6	TP IPV7	TP DPV8

Less than 50%	NR	NR	0.043	TBD

50.1 – 60.0%	NR	NR	0.043	TBD

60.1 – 70.0%	NR	NR	0.043	TBD

70.1 – 80.0%	NR	NR	0.043	TBD

80.1 – 90.0%	0.824	0.48	0.043	TBD

90.1 – 100%	0.824	0.43	0.043	TBD



Choctawhatchee Bay WatershedPH (EDA Code1: G120x)

Protective TN Load for the Estuary2: 2,875,861 kg y-1

Protective TP Load for the Estuary3: TBD

River/Stream Reach Category - 

Percent Delivered to Estuary4	TN (mg L-1)	TP (mg L-1)

	TN IPV5	TN DPV6	TP IPV7	TP DPV8

Less than 50%	NR	NR	0.043	TBD

50.1 – 60.0%	NR	NR	0.043	TBD

60.1 – 70.0%	NR	NR	0.043	TBD

70.1 – 80.0%	0.824	0.48	0.043	TBD

80.1 – 90.0%	0.824	0.43	0.043	TBD

90.1 – 100%	0.824	0.39	0.043	TBD



St. Andrew Bay WatershedPH (EDA Code1: G110x)

Protective TN Load for the Estuary2: 310,322 kg y-1

Protective TP Load for the Estuary3: TBD

River/Stream Reach Category - 

Percent Delivered to Estuary4	TN (mg L-1)	TP (mg L-1)

	TN IPV5	TN DPV6	TP IPV7	TP DPV8

Less than 50%	0.824	0.48	0.043	TBD

50.1 – 60.0%	NR	NR	0.043	TBD

60.1 – 70.0%	NR	NR	0.043	TBD

70.1 – 80.0%	0.824	0.30	0.043	TBD

80.1 – 90.0%	0.824	0.27	0.043	TBD

90.1 – 100%	0.824	0.24	0.043	TBD



Apalachicola Bay WatershedPH (EDA Code1: G100x)

Protective TN Load for the Estuary2: 10,971,582 kg y-1

Protective TP Load for the Estuary3: TBD

River/Stream Reach Category - 

Percent Delivered to Estuary4	TN (mg L-1)	TP (mg L-1)

	TN IPV5	TN DPV6	TP IPV7	TP DPV8

Less than 50%	0.824	0.91	0.043	TBD

50.1 – 60.0%	NR	NR	0.043	TBD

60.1 – 70.0%	0.824	0.65	0.043	TBD

70.1 – 80.0%	0.824	0.57	0.043	TBD

80.1 – 90.0%	0.824	0.51	0.043	TBD

90.1 – 100%	0.824	0.46	0.043	TBD



Apalachee Bay WatershedPH (EDA Code1: G090x)

Protective TN Load for the Estuary2: 2,539,883 kg y-1

Protective TP Load for the Estuary3: TBD

River/Stream Reach Category - 

Percent Delivered to Estuary4	TN (mg L-1)	TP (mg L-1)

	TN IPV5	TN DPV6	TP IPV7	TP DPV8

Less than 50%	NR	NR	0.043	TBD

50.1 – 60.0%	NR	NR	0.043	TBD

60.1 – 70.0%	NR	NR	0.043	TBD

70.1 – 80.0%	0.824	0.67	0.043	TBD

80.1 – 90.0%	0.824	0.59	0.043	TBD

90.1 – 100%	0.824	0.53	0.043	TBD



Econfina/Steinhatchee Coastal Drainage AreaPH (CDA Code1: G086x)

Protective TN Load for the Estuary2: 185,301 kg y-1

Protective TP Load for the Estuary3: TBD

River/Stream Reach Category - 

Fraction Delivered to Estuary4	TN (mg L-1)	TP (mg L-1)

	TN IPV5	TN DPV6	TP IPV7	TP DPV8

Less than 50%	NR	NR	0.043	TBD

50.1 – 60.0%	NR	NR	0.043	TBD

60.1 – 70.0%	NR	NR	0.043	TBD

70.1 – 80.0%	NR	NR	0.043	TBD

80.1 – 90.0%	0.824	0.41	0.043	TBD

90.1 – 100%	0.824	0.37	0.043	TBD



Suwannee River WatershedNC (EDA Code1:G080x)

Protective TN Load for the Estuary2: 5,421,050 kg y-1

Protective TP Load for the Estuary3: TBD

River/Stream Reach Category - 

Percent Delivered to Estuary4	TN (mg L-1)	TP (mg L-1)

	TN IPV5	TN DPV6	TP IPV7	TP DPV8

Less than 50%	NR	NR	0.359	TBD

50.1 – 60.0%	NR	NR	0.359	TBD

60.1 – 70.0%	1.479	0.78	0.359	TBD

70.1 – 80.0%	1.479	0.69	0.359	TBD

80.1 – 90.0%	1.479	0.61	0.359	TBD

90.1 – 100%	1.479	0.55	0.359	TBD



Waccasassa Coastal Drainage AreaPN (CDA Code1: 078x)

Protective TN Load for the Estuary2:  433,756 kg y-1

Protective TP Load for the Estuary3: TBD

River/Stream Reach Category - 

Percent Delivered to Estuary4	TN (mg L-1)	TP (mg L-1)

	TN IPV5	TN DPV6	TP IPV7	TP DPV8

Less than 50%	NR	NR	0.107	TBD

50.1 – 60.0%	NR	NR	0.107	TBD

60.1 – 70.0%	NR	NR	0.107	TBD

70.1 – 80.0%	NR	NR	0.107	TBD

80.1 – 90.0%	1.205	0.45

	0.107	TBD

90.1 – 100%	1.205	0.40	0.107	TBD



Withlacoochee Coastal Drainage AreaPN (CDA Code1: G076x)

Protective TN Load for the Estuary2:  TBD

Protective TP Load for the Estuary3: TBD

River/Stream Reach Category - 

Percent Delivered to Estuary4	TN (mg L-1)	TP (mg L-1)

	TN IPV5	TN DPV6	TP IPV7	TP DPV8

Less than 50%	1.205	TBD	0.107	TBD

50.1 – 60.0%	1.205	TBD	0.107	TBD

60.1 – 70.0%	1.205	TBD	0.107	TBD

70.1 – 80.0%	1.205	TBD	0.107	TBD

80.1 – 90.0%	1.205	TBD	0.107	TBD

90.1 – 100%	1.205	TBD	0.107	TBD



Crystal/Pithlachascotee Coastal Drainage AreaPN (CDA Code1: G074x)

Protective TN Load for the Estuary2: TBD

Protective TP Load for the Estuary3: TBD

River/Stream Reach Category - 

Percent Delivered to Estuary4	TN (mg L-1)	TP (mg L-1)

	TN IPV5	TN DPV6	TP IPV7	TP DPV8

Less than 50%	1.205	TBD	0.107	TBD

50.1 – 60.0%	NR	TBD	0.107	TBD

60.1 – 70.0%	NR	TBD	0.107	TBD

70.1 – 80.0%	NR	TBD	0.107	TBD

80.1 – 90.0%	1.205	TBD	0.107	TBD

90.1 – 100%	1.205	TBD	0.107	TBD



Tampa Bay WatershedBV (EDA Code1: G070x)

Protective TN Load for the Estuary2: 1,289,671 kg y-1

Protective TP Load for the Estuary3: TBD

River/Stream Reach Category - 

Percent Delivered to Estuary4	TN (mg L-1)	TP (mg L-1)

	TN IPV5	TN DPV6	TP IPV7	TP DPV8

Less than 50%	1.798	1.11	0.739	TBD

50.1 – 60.0%	1.798	0.93	0.739	TBD

60.1 – 70.0%	1.798	0.80	0.739	TBD

70.1 – 80.0%	1.798	0.70	0.739	TBD

80.1 – 90.0%	1.798	0.62	0.739	TBD

90.1 – 100%	1.798	0.56	0.739	TBD



Sarasota Bay WatershedBV (EDA Code1: G060x)

Protective TN Load for the Estuary2: 155,576 kg y-1

Protective TP Load for the Estuary3: TBD

River/Stream Reach Category - 

Percent Delivered to Estuary4	TN (mg L-1)	TP (mg L-1)

	TN IPV5	TN DPV6	TP IPV7	TP DPV8

Less than 50%	NR	NR	0.739	TBD

50.1 – 60.0%	NR	NR	0.739	TBD

60.1 – 70.0%	NR	NR	0.739	TBD

70.1 – 80.0%	NR	NR	0.739	TBD

80.1 – 90.0%	NR	NR	0.739	TBD

90.1 – 100%	1.798	0.54	0.739	TBD



Charlotte Harbor WatershedBV (EDA Code1: G050w)

Protective TN Load for the Estuary2: 2,710,107 kg y-1

Protective TP Load for the Estuary3: TBD

River/Stream Reach Category - 

Percent Delivered to Estuary4	TN (mg L-1)	TP (mg L-1)

	TN IPV5	TN DPV6	TP IPV7	TP DPV8

Less than 50%	NR	NR	0.739	TBD

50.1 – 60.0%	1.798	1.58	0.739	TBD

60.1 – 70.0%	1.798	1.35	0.739	TBD

70.1 – 80.0%	1.798	1.18	0.739	TBD

80.1 – 90.0%	1.798	1.05	0.739	TBD

90.1 – 100%	1.798	0.95	0.739	TBD



Indian River Watershed PN (EDA Code1: S190x)

Protective TN Load for the Estuary2: 463,724 kg y-1

Protective TP Load for the Estuary3: TBD

River/Stream Reach Category - 

Percent Delivered to Estuary4	TN (mg L-1)	TP (mg L-1)

	TN IPV5	TN DPV6	TP IPV7	TP DPV8

Less than 50%	NR	NR	0.107	TBD

50.1 – 60.0%	NR	NR	0.107	TBD

60.1 – 70.0%	NR	NR	0.107	TBD

70.1 – 80.0%	1.205	0.87

	0.107	TBD

80.1 – 90.0%	1.205	0.77	0.107	TBD

90.1 – 100%	1.205	0.69	0.107	TBD



Caloosahatchee River WatershedPN, # (EDA Code1: G050a)

Protective TN Load for the Estuary2: TBD

Protective TP Load for the Estuary3: TBD

River/Stream Reach Category - 

Percent Delivered to Estuary4	TN (mg L-1)	TP (mg L-1)

	TN IPV5	TN DPV6	TP IPV7	TP DPV8

Less than 50%	1.205	TBD	0.107	TBD

50.1 – 60.0%	1.205	TBD	0.107	TBD

60.1 – 70.0%	1.205	TBD	0.107	TBD

70.1 – 80.0%	1.205	TBD	0.107	TBD

80.1 – 90.0%	1.205	TBD	0.107	TBD

90.1 – 100%	1.205	TBD	0.107	TBD



St. Lucie River WatershedPN, # (EDA Code1: S190x)

Protective TN Load for the Estuary2: TBD

Protective TP Load for the Estuary3: TBD

River/Stream Reach Category - 

Percent Delivered to Estuary4	TN (mg L-1)	TP (mg L-1)

	TN IPV5	TN DPV6	TP IPV7	TP DPV8

Less than 50%	1.205	TBD	0.107	TBD

50.1 – 60.0%	1.205	TBD	0.107	TBD

60.1 – 70.0%	1.205	TBD	0.107	TBD

70.1 – 80.0%	1.205	TBD	0.107	TBD

80.1 – 90.0%	1.205	TBD	0.107	TBD

90.1 – 100%	1.205	TBD	0.107	TBD



Kissimmee River Watershed PN, ^

Protective TN Load for the Estuary2:  TBD

Protective TP Load for the Estuary3: TBD

River/Stream Reach Category - 

Percent Delivered to Estuary4	TN (mg L-1)	TP (mg L-1)

	TN IPV5	TN DPV6, LO	TP IPV7	TP DPV8, LO

Less than 50%	1.205	TBD9	0.107	TBD9

50.1 – 60.0%	1.205	TBD9	0.107	TBD9

60.1 – 70.0%	1.205	TBD9	0.107	TBD9

70.1 – 80.0%	1.205	TBD9	0.107	TBD9

80.1 – 90.0%	1.205	TBD9	0.107	TBD9

90.1 – 100%	1.205	TBD9	0.107	TBD9



St. John’s River Watershed PN (EDA Code1: S180x)

Protective TN Load for the Estuary2: 4,954,662 kg y-1

Protective TP Load for the Estuary3: TBD

River/Stream Reach Category - 

Percent Delivered to Estuary4	TN (mg L-1)	TP (mg L-1)

	TN IPV5	TN DPV6	TP IPV7	TP DPV8

Less than 50%	1.205	1.41	0.107	TBD

50.1 – 60.0%	1.205	1.17	0.107	TBD

60.1 – 70.0%	1.205	1.00	0.107	TBD

70.1 – 80.0%	1.205	0.88	0.107	TBD

80.1 – 90.0%	1.205	0.78	0.107	TBD

90.1 – 100%	1.205	0.70	0.107	TBD



Daytona/St. Augustine Coastal Drainage AreaPN (CDA Code1: S183x)

Protective TN Load for the Estuary2:  TBD

Protective TP Load for the Estuary3:  TBD

River/Stream Reach Category - 

Percent Delivered to Estuary4	TN (mg L-1)	TP (mg L-1)

	TN IPV5	TN DPV6	TP IPV7	TP DPV8

Less than 50%	NR	TBD	0.107	TBD

50.1 – 60.0%	NR	TBD	0.107	TBD

60.1 – 70.0%	NR	TBD	0.107	TBD

70.1 – 80.0%	NR	TBD 	0.107	TBD

80.1 – 90.0%	1.205	TBD	0.107	TBD

90.1 – 100%	1.205	TBD	0.107	TBD



Nassau Coastal Drainage AreaPN (CDA Code1: S175x)

Protective TN Load for the Estuary2: 131,389 kg y-1

Protective TP Load for the Estuary3: TBD

River/Stream Reach Category - 

Percent Delivered to Estuary4	TN (mg L-1)	TP (mg L-1)

	TN IPV5	TN DPV6	TP IPV7	TP DPV8

Less than 50%	1.205	0.59	0.107	TBD

50.1 – 60.0%	NR	NR	0.107	TBD

60.1 – 70.0%	NR	NR	0.107	TBD

70.1 – 80.0%	NR	NR	0.107	TBD

80.1 – 90.0%	1.205	0.33	0.107	TBD

90.1 – 100%	1.205	0.30	0.107	TBD



St. Mary’s River WatershedPN (EDA Code1: S170x)

Protective TN Load for the Estuary2: 562,644 kg y-1

Protective TP Load for the Estuary3: TBD

River/Stream Reach Category - 

Percent Delivered to Estuary4	TN (mg L-1)	TP (mg L-1)

	TN IPV 5	TN DPV6	TP IPV 7	TP DPV8

Less than 50%	NR	NR	0.107	TBD

50.1 – 60.0%	NR	NR	0.107	TBD

60.1 – 70.0%	NR	NR	0.107	TBD

70.1 – 80.0%	1.205	0.43	0.107	TBD

80.1 – 90.0%	1.205	0.38	0.107	TBD

90.1 – 100%	1.205	0.34	0.107	TBD



Footnotes associated with this table:  

1 Watershed delineated by NOAA’s Coastal Assessment Framework and
associated Florida Department of Environmental Protection’s estuarine
and coastal water body identifier (WBID).

2 Estimated TN load delivered to the estuary protective of aquatic life
use.  These estimates may be revised pursuant to the EPA final rule for
numeric nutrient criteria for Florida’s estuaries and coastal waters
(October 2011).

3 Estimated TP load delivered to the estuary protective of aquatic life
use.  These estimates are currently under development.  Preliminary
estimates may be revised pursuant to the EPA final rule for numeric
nutrient criteria for Florida’s estuaries and coastal waters (October
2011).

4 River/Stream reach categories within each estuarine watershed are
linked spatially to a specific FDEP water body identifier (WBID). See
Appendix B-18 of the "Technical Support Document for EPA's Proposed Rule
for Numeric Nutrient Criteria for Florida's Inland Surface Fresh
Waters.”

5 Instream Protection Value (IPV) is the TN concentration protective of
instream aquatic life use.  

6 Downstream protection values (DPVs) are estimated TN concentrations in
the river/stream reach that meet the estimated TN load, protective of
aquatic life use, delivered to the estuarine waters.  These estimates
may be revised pursuant to the EPA final rule for numeric nutrient
criteria for Florida’s estuaries and coastal waters (October 2011).

7 Instream Protection Value (IPV) is the TP concentration protective of
instream aquatic life use.  

8 Downstream protection values (DPVs) are estimated TP concentrations in
the river/stream reach that meet the estimated TP load, protective of
aquatic life use, delivered to the estuarine waters.  These estimates
are currently under development.  Preliminary estimates may be revised
pursuant to the EPA final rule for numeric nutrient criteria for
Florida’s estuaries and coastal waters (October 2011).

9 EPA’s proposed TN and TP criteria for colored lakes (> 40 PCU) are
1.2 and 0.050 mg L-1, respectively.

# Estimated TN and TP loads protective of aquatic life in the
Caloosahatchee and St. Lucie River estuaries, and in turn estimated TN
and TP concentrations that would meet those protective loads, could not
be calculated using EPA’s downstream protection approach. An
alternative downstream protection approach will be proposed in EPA’s
proposed rule for FL estuaries (January 2011).

^ Kissimmee River watershed does not have an EDA or CDA code because it
does not drain directly to an estuary or coastal area, but rather
indirectly through Lake Okeechobee and the south Florida canal system. 
A protective TN and TP load for Lake Okeechobee has not been calculated,
however, a TMDL is in effect for TP.  EPA’s proposed colored lake
criteria (> 40 PCU) could be used to develop DPVs for TN and TP for the
Kissimmee watershed (see footnote 9).

LO DPVs to be based on protective TN and TP loads for Lake Okeechobee. 
EPA’s proposed colored lake criteria (> 40 PCU) could be used to
develop DPVs for TN and TP for the Kissimmee watershed (see footnote 9).

NR There are no stream reaches present in this watershed that have a
percent-delivered within this range and thus criteria are not
applicable.. 

PH Panhandle Nutrient Watershed Region.

BV Bone Valley Nutrient Watershed Region.

PN Peninsula Nutrient Watershed Region.

NC North Central Nutrient Watershed Region

TBD To be determined.

(v)  Application of DPVs for Downstream Estuary Protection

The following discussion further explains the conceptual relationship
between IPVs and DPVs for stream criteria.  EPA developed IPVs to
protect the uses that occur within the stream itself at the point of
application, such as protection of the benthic invertebrate community
and maintenance of a healthy balance of phytoplankton species.  In
contrast, EPA developed DPVs for streams to protect WQS of downstream
waters.  EPA derived DPVs in Florida streams by distributing the
protective load from the aggregate stream network identified for each
downstream estuary (that is protective of estuarine conditions) across
the watershed in proportion to the amount of flow contributed by each
stream reach.  EPA’s approach also accounts for attenuation of
nutrients (or loss from the system) as water travels from locations
upstream in the watershed to locations near the mouth of the estuary.  

When comparing an IPV and DPV that are each deemed to apply to a
particular stream segment, the more stringent of the two values is the
numeric nutrient criterion that would need to be met when implementing
CWA programs.  Water bodies can differ significantly in their
sensitivity to nutrients in general and to TN specifically.  Although
not universally true, freshwaters are generally phosphorus-limited and
thus more sensitive to phosphorus enrichment because nitrogen is present
in excess.  Enriching freshwaters with phosphorus does not usually drive
these systems into nitrogen limitation but can simply encourage growth
of nitrogen-fixing algal species which can convert atmospheric nitrogen
into ammonia.  Conversely, estuaries are more often nitrogen limited and
thus more sensitive to adverse impacts from nitrogen enrichment.  As a
result, it is not at all surprising that DPVs for TN in Florida are
often less than the corresponding IPVs.

Adjustments to DPVs are possible with a redistribution approach, which
revises the original uniform assignment of protective downstream
estuarine loadings across the estuarine drainage area using the DPV
methodology, or by revising either the protective load delivered to the
downstream estuary and/or the equivalent DPVs using a technical approach
of comparable scientific rigor and the Federal SSAC procedure described
in section V.C of this notice.

nlike re-allocation of an even distribution of loading, these types of
adjustments, as well as other site-specific information on alternative
fractions delivered, would require use of the SSAC procedure under this
proposal.  EPA requests comment on whether these adjustments should be
allowed to occur in the implementation of the re-allocation process
rather than as a SSAC.   

A technical approach of comparable scientific rigor will include a
systematic data driven evaluation and accompanying analysis of relevant
factors to identify a protective load delivered to the estuary.  An
acceptable alternate numeric approach also includes a method to
distribute and apply the load to streams and other waters within the
estuarine drainage area in a manner that recognizes conservation of mass
and makes use of a peer-reviewed model (empirical or mechanistic) of
comparable or greater rigor and scientific defensibility than the USGS
SPARROW model.  To use an alternative technical approach, the State must
go through the process for a Federal SSAC procedure as described in
Section V.C.

EPA requests comment on the DPV approach, the technical merit of the
estimated protective loadings, and the technical merit of the method for
calculating stream reach values.  EPA also requests comment on other
scientifically defensible approaches for ensuring protection of
designated uses in estuaries.  At this time, EPA plans to take final
action with respect to downstream protection values for nitrogen as part
of the second phase of this rulemaking process in coordination with the
proposal and finalization of numeric standards for estuarine and coastal
waters in 2011.  However, if comments, data and analyses submitted as a
result of this proposal support finalizing these values sooner, by
October 2010, EPA may choose to proceed in this manner.  To facilitate
this process, EPA requests comments and welcomes thorough evaluation on
the technical and scientific basis of these proposed downstream
protection values as part of the broader comment and evaluation process
that this proposal initiates.

D.  Proposed Numeric Nutrient Criteria for the State of Florida’s
Springs and Clear Streams

(1)  Proposed Numeric Nutrient Criteria for Springs and Clear Streams

	Springs and their associated spring runs in Florida are a unique class
of aquatic ecosystem, highly treasured for their biological, economic,
aesthetic, and recreational value.  Globally, the largest number of
springs (per unit of area), occur in Florida; Florida has over 700
springs and associated spring runs.  Many of the larger spring
ecosystems in Florida have likely been in existence since the end of the
last major ice age

 (approximately 15,000 to 30,000 years ago).  The productivity of the
diverse assemblage of aquatic flora and fauna in Florida springs is
primarily determined by the naturally high amount of light availability
of these waters (naturally high clarity).  As recently as 50 years ago,
these waters were considered by naturalists and scientists to be some of
the most unique and exceptional waters in the State of Florida and the
Nation as a whole.  

	In Florida, springs are also highly valued as a water resource for
human use: people use springs for a variety of recreational purposes and
are interested in the intrinsic aesthetics of clear, cool water
emanating vigorously from beneath the ground.  A good example of the
value of springs in Florida is the use of the spring boil areas that
have sometimes been modified to encourage human recreation (bathing or
swimming). 

	Over the past two decades, scientists have identified two significant
anthropogenic factors linked to adverse changes in spring ecosystems
that have the potential to permanently alter Florida’s spring
ecosystems.  These are:  1) pollution of groundwater, principally with
nitrate-nitrite, resulting from human land use changes, cultural
practices, and explosive population growth; and 2) simultaneous
reductions in groundwater supply from human withdrawals.  Pollution
associated with human activities is one of the most critical issues
affecting the health of Florida’s springs.  

	Excess nutrients, in particular excess nitrogen, seep into the soils
and move to groundwater.  When in excess, nutrients lead to
eutrophication of groundwater-fed springs, allowing algae and invasive
plant species to displace native plants, which in turn results in an
ecological imbalance.  Excessive growth of nuisance algae and noxious
plant species in turn result in reduced habitat and food sources for
native wildlife, excess organic carbon production, accelerated
decomposition, and lowered quality of the floor or “bottom” of
springs and spring runs, all of which adversely impact the overall
health and aesthetics of Florida’s springs.

	Adverse impacts on the overall health of Florida’s springs have been
evident over the past several decades.  Within the last 20-30 years,
observations at several of Florida’s springs suggest that nuisance
algae species have proliferated, and are now out-competing and replacing
native submerged vegetation.  Numerous biological studies have
documented excessive algal growth at many major springs.  In some of the
more extreme examples, such as Silver Springs and Weeki Wachee Springs,
algal mat accumulations have become over three feet thick.,  

	As a result of human-induced land use changes, cultural practices, and
explosive population growth, there has been an increase in the level of
pollutants, especially nitrate, in groundwater over the past decades. 
Because there is no geologic source of nitrogen in springs, all of the
nitrogen emerging in spring vents originates from that which is
deposited on the land.  Historically, nitrate concentrations in
Florida’s spring discharges were thought to have been around 0.05 mg/L
or less, which is sufficiently low to restrict growth of algae and
vegetation under “natural” conditions.  

	Regions where springs emanate in Florida have experienced unprecedented
population growth and changes in land use over the past several decades.
 With these changes in population and growth came a transfer of
nutrients, particularly nitrate, to groundwater.  Of 125 spring vents
sampled by the Florida Geological Survey in 2001-2002, 42% had nitrate
concentrations exceeding 0.50 mg/L and 24% had concentrations greater
than 1.0 mg/L.  Similarly, a recent evaluation of water quality in 13
springs shows that mean nitrate-nitrite levels have increased from 0.05
mg/L to 0.9 mg/L between 1970 and 2002.  Overall, data suggest that
nitrate-nitrite concentrations in many spring discharges have increased
from 10 to 350 fold over the past 50 years, with the level of increase
closely correlated with anthropogenic activity and land use changes
within the karst regions of Florida where springs predominate.  

	As nitrate-nitrite concentrations have increased during the past 20 to
50 years, many Florida springs have undergone adverse environmental and
biological changes.  According to FDEP, there is a general consensus in
the scientific community that nitrate is an important factor leading to
the observed changes in spring ecosystems, and their associated
biological communities.  Nitrogen, particularly nitrate-nitrite, appears
to be the most problematic nutrient problem in Florida’s karst region.
 

	Because nitrate-nitrite has been linked to many of the observed
detrimental impacts in spring ecosystems, there is an immediate need to
reduce nitrate-nitrite concentrations in spring vents and groundwater. 
A critical step in achieving reductions in nitrate-nitrite is to develop
a numeric nitrate-nitrite criterion for spring systems that will be
protective of these unique and treasured resources.  

	To protect springs and clear streams and to provide assessment levels
and restoration goals for those that have already been impaired by
nutrients, EPA is proposing numeric nutrient criteria for the following
parameter for Florida’s springs and clear streams (< 40 PCU)
classified as Class I or III waters under Florida law (Rule 62-302.400,
F.A.C.): 

Nitrate (NO3-)+Nitrite (NO2-) shall not surpass a concentration of 0.35
mg/L as an annual geometric mean more than once in a three-year period,
nor surpassed as a long-term average of annual geometric mean values.

In addition to the nitrate-nitrite criterion, TN and TP criteria
developed for streams on a watershed basis are also applicable to clear
streams.  See Section III.C(1) “Proposed Numeric Nutrient Criteria for
the State of Florida’s Rivers and Streams” for the table of proposed
TN and TP criteria that would apply to clear streams located within
specific watersheds.

(2)  Methodology for Deriving EPA’s Proposed Criteria for Springs and
Clear Streams

EPA’s proposed nitrate-nitrite criterion for springs and clear streams
are derived from a combination of FDEP laboratory data, field surveys,
and analyses which include analyses conducted to determine the stressor
response-based thresholds that link nitrate-nitrite levels to biological
risk in springs and clear streams.  These data document the response of
nuisance algae, Lyngbya wollei and Vaucheria sp., and periphyton to
nitrate-nitrite concentrations.  Please refer to EPA’s TSD for
Florida’s Inland Waters, Chapter 3: Methodology for Deriving U.S.
EPA’s Proposed Criteria for Springs and Clear Streams.

As described in Section III.C(2), the ability to establish protective
criteria for both causal and response variables depends on available
data and scientific approaches to evaluate these data.  EPA has not
undertaken the development of TP criteria for springs because phosphorus
has historically been present in Florida’s springs, given the
State’s naturally phosphorus-rich geology, and the lack of an
increasing trend of phosphorus concentrations in most spring discharges.
 EPA is not proposing chlorophyll a and clarity criteria due to the lack
of available data for these response variables in spring systems. 
Furthermore, scientific evidence examining the strong relationship
between rapid periphyton survey data (measurements of the thickness of
algal biomass attached to substrate rather than free-floating) and
nutrients in clear streams (those with color <40 PCU and canopy cover
≤ 40% which are comparable to most waters found in springs and spring
runs) show that benthic algal thickness is highly dependent on nitrogen
parameters (TN and total inorganic nitrogen), as opposed to phosphorus. 
In addition, EPA is proposing to apply the nitrate-nitrite criteria
derived for springs to clear streams as a measure to gauge anthropogenic
contributions to TN.  EPA is not currently proposing criteria for
clarity and chlorophyll a for clear streams due to the lack of
scientific evidence supporting the relationship between these response
variables and nutrients.  Clear streams show weak relationships between
nutrients and chlorophyll a, as opposed to color streams where
phytoplankton responses occur more readily than periphyton growth. 
Please refer to EPA’s TSD for Florida’s Inland Waters, Chapter 3:
Methodology for Deriving U.S. EPA’s Proposed Criteria for Springs and
Clear Streams.

	(a)  Derivation of Proposed Nitrate-Nitrite Criteria

EPA’s goal in deriving nitrate-nitrite criteria for Florida springs
and clear streams is to ensure that the criteria will preserve the
ecosystem structure and function of Florida’s springs and clear
streams.  EPA reviewed Florida data, FDEP’s approach and analyses, and
FDEP’s proposed nitrate-nitrite criterion for springs and clear
streams and has concluded that the FDEP approach and the values FDEP
derived represent a scientifically sound basis for the derivation of
these criteria.  FDEP evaluated results from laboratory scale dosing
studies, data from in-situ algal monitoring, real-world surveys of
biological communities and nutrient levels in Florida springs, and data
on nitrate-nitrite concentrations found in minimally-impacted reference
locations.

FDEP analyzed laboratory data that evaluated the growth response of
nuisance algae to nitrate addition.  FDEP’s analysis showed that
Lyngbya wollei and Vaucheria sp. reached 90% of their maximum growth at
0.230 mg/L and 0.261 mg/L nitrate-nitrite, respectively.  FDEP also
reviewed long-term field surveys that examined the response of nuisance
algae, periphyton, and eutrophic indicator diatoms to nitrate-nitrite
concentration.  The results showed a sharp increase in abundance and/or
biomass of the nuisance algae, periphyton, and diatoms at 0.44 mg/L
nitrate-nitrite.

FDED also reviewed the field surveys used to develop TMDLs for Wekiva
River and Rock Spring Run to evaluate the relationship between the
observed excessive algal growth and imbalance in aquatic flora with
measurements of nutrients in these particular systems.  FDEP found that
taxa indicative of eutrophic conditions increased significantly with
increasing nitrate-nitrite concentrations above approximately 0.35 mg/L.
 

Based on its review of a combination of this laboratory and field data,
FDEP concluded that significant alterations in community composition
(eutrophic indicator diatoms), in combination with an increase in
periphyton cell density and biomass, clearly demonstrate that a
nitrate-nitrite level in the range between 0.23 mg/L (the laboratory
threshold) and 0.44 mg/L (the field study derived value associated with
the upper bound nitrate-nitrite concentration where substantial observed
biological changes were apparent) is the amount of nitrate-nitrite
associated with an imbalance of aquatic flora in spring systems.

FDEP conducted further statistical analyses of the available data from
the multiple lines of evidence, applied an appropriate safety factor to
ensure that waters would not reach the nitrate-nitrite levels associated
with “substantial observed biological changes,” and averaged the
results to arrive at a final protective threshold value for
nitrate-nitrite in springs and clear streams of 0.35 mg/L.  Based on the
discussion above and corresponding analysis in the TSD for Florida’s
Inland Waters, EPA has concluded that this value was derived in a
scientifically sound manner, appropriately considering the available
data, and appropriately interpreting the multiple lines of evidence. 
Accordingly, EPA is proposing 0.35 mg/L nitrate-nitrite as a protective
criterion for aquatic life in Florida’s springs and clear streams.  

(b)  Proposed Criteria:  Duration and Frequency

EPA is proposing a duration and frequency expression of an annual
geometric mean not to be surpassed more than once in a three-year period
to be consistent with the expressions of duration and frequency for
other water body types (e.g., lakes, streams, canals) for TN and TP and
for the same reasons EPA selected a three-year period for those waters. 
Second, EPA proposes that the long-term arithmetic average of annual
geometric means not exceed the criterion-magnitude concentration.  EPA
anticipates that Florida will use its standard assessment periods as
specified in Rule 62-303, F.A.C. (Impaired Waters Rule) to implement
this second provision.   EPA has determined that this frequency of
excursions should not result in unacceptable effects on aquatic life as
it will allow the springs and clear streams aquatic systems enough time
to recover from an occasionally elevated year of nutrient loadings.  The
Agency requests comment on these proposed duration and frequency
expressions of the springs and clear streams numeric nutrient criteria.

EPA also considered as an alternative, expressing the criterion as a
monthly median not to be surpassed more than 10% of the time.  Stated
another way, the median value over any given calendar month shall not be
higher than the criterion-magnitude value in more than one out of every
ten months.  It is appropriate to express a monthly criterion as a
median because the median is less susceptible to outliers than the
geometric mean.  This is particularly important when dealing with small
sample sizes.  This alternative is consistent with the expression that
FDEP proposed in July 2009 for its State rule and the expression in the
TSD for Florida’s Inland Waters that EPA sent out for external
scientific peer review in July 2009.  The rationale for this alternative
is that field data indicate that the response in springs is correlated
to monthly exposure at the criterion-magnitude concentration value and a
10% frequency of excursions is a reasonable and fully protective
allowance given small sample sizes in any given month (i.e., the
anticipated amount of data that will be available for assessment
purposes in the future).  The clear streams nitrate-nitrite criterion
was derived by FDEP based on multiple lines of evidence, with the
primary lines of evidence being mesocosm dosing experiments and field
studies.  These two main studies were conducted by FDEP over very
different time frames.  One set of mesocosm studies was conducted by
FDEP for periods just under one month (i.e., 21 to 28 days), while
another, the algal biomass field survey, was conducted over an 18-year
period and was analyzed using four to five year averaging periods. 
While lab studies indicate that algal communities can respond to excess
nitrate-nitrite over a short period of time, the mesocosm and other
dosing studies indicate that this response occurs on the order of a
month, which might support a monthly expression of the criterion. 
However, there is no evidence to suggest that the responses observed
within a month under controlled lab settings equate to impairment of the
designated use in conditions experienced in State waters.  Please refer
to EPA’s TSD for Florida’s Inland Waters, Chapter 3: Methodology for
Deriving U.S. EPA’s Proposed Criteria for Springs and Clear Streams.

The 10% excursion frequency would recognize that in most cases the
monthly “median” would actually be based on a single sample, given
that most springs are only sampled monthly at the most.  A 10% excursion
frequency may be considered a reasonable and fully protective allowance
given small sample sizes in any given month, essentially requiring that
the monthly median nitrate-nitrate concentrations thought to be fully
supportive of relevant designated uses be met 90% of the time.

) a criterion-frequency expressed as meeting the allowable magnitude and
duration as a long-term average only.  EPA further requests comment on
whether an expression of the criteria in terms of an arithmetic average
of annual geometric mean values based on rolling three-year periods of
time would also be protective of the designated use.

 (3)  Request for Comment and Data on Proposed Approach

EPA believes the proposed nutrient criterion for springs and clear
streams in this rule are protective of the designated aquatic life use
of these waters in Florida.  EPA is soliciting comment on the approach
FDEP used and EPA adopted to derive nitrate-nitrite criterion for
springs and clear streams, including the data and analyses underlying
the proposed criterion.  EPA is seeking additional, readily-available,
pertinent data and information related to nutrient concentrations or
nutrient responses in springs and clear streams in Florida.  EPA is also
soliciting views on other potential, scientifically sound approaches to
deriving protective nitrate-nitrite criterion for springs and clear
streams in Florida.

	(4)  Alternative Approaches:  Nitrate-Nitrite Criterion for All Waters
as an Independent Criterion

EPA is soliciting comment on the environmental benefits associated with
deriving a nitrate-nitrite criterion for all waters covered by this
proposal (i.e., all streams, lakes, and canals), in addition to the
other proposed nutrient criteria for those water bodies.  Adoption of a
nitrate-nitrite criterion for waters other than springs and clear
streams could be useful from an assessment and management perspective. 
Florida could use nitrate-nitrite data to identify increasing trends
that may indicate the need for more specific controls of certain
nitrogen enrichment sources.  In cases where waters are impaired for
either TN, nitrate-nitrite, or both TN and nitrate-nitrite, FDEP could
use the nitrate-nitrite data to potentially target discharges of
anthropogenic origin given their relative source contribution to
nitrogen enrichment.  

This alternative approach, which would involve EPA deriving
nitrate-nitrite criteria for all waters or alternatively applying 0.35
mg/L nitrate-nitrite to all waters, could provide additional protection
for aquatic life designated uses.  The alternative approach would also
eliminate the need for FDEP to characterize streams as clear or not.
Deriving and applying a nitrate-nitrite criterion to all waters would
reduce the likelihood of excess loading of the specific anthropogenic
components of TN to colored waters.  However, these colored streams may
be less likely to show an observed response to nitrate-nitrite due to
the presence of tannins that block light penetration.  Thus, the
presence of color in streams may confound the relationship that produced
the 0.35 mg/L nitrate-nitrite criterion.  

E.  Proposed Numeric Nutrient Criteria for South Florida Canals  

(1)  Proposed Numeric Nutrient Criteria for South Florida Canals

There are thousands of miles of canals in Florida, particularly in the
southeastern part of the State.  Canals are artificial waterways that
are either the result of modifications to existing rivers or streams, or
waters that have been created for various purposes, including drainage
and flood control (stormwater management), irrigation, navigation, and
recreation.  These canals also allow for the creation of many waterfront
home sites in Florida.  Ecosystems that existed in rivers and streams
prior to their modification into canals are altered.  These changes can
affect fish and wildlife and plant growth, as further explained in the
following paragraphs.  Newly created canals may have a tendency to fill
with aquatic plants.  Canals in south Florida vary greatly in size and
depth.  They can be anywhere from a few feet wide and a few feet deep to
hundreds of feet wide and as deep as 30-35 feet.

South Florida canals vary in their hydrology and behavior due to their
size, function, and seasonality.  Shallow canals with slow water flow
have poor turnover of water and little flushing.  Large canals also may
have low flow and turnover during the dry season.  In contrast, during
the wet season these same large canals are flowing systems that quickly
move large volumes of water, as they were designed to accomplish. 
Excess nutrients in canals in combination with poor water circulation
and decreased levels of dissolved oxygen, can lead to accelerated
eutrophication and adverse impacts on other forms of aquatic life such
as fish and other aquatic animals.  In these canals, the accumulation of
decaying organic matter on the canal bottom can also adversely impact
healthy aquatic ecosystems.  

South Florida canals are highly managed waterways.  Some canals are
prone to an over-abundance of aquatic plants.  Without regular and
frequent management, dense vegetation can clog the waterways making
navigation difficult and slowing the movement of water through the canal
system.  This can interfere with flood control, boating, and fishing. 
Aquatic plants (like plants in the terrestrial environment) respond and
grow when fertilized with nutrients such as phosphorus and nitrogen, and
thus nutrient runoff into canals is likely a significant contributor to
both nuisance algal blooms and clogging of canal systems by aquatic
plants.

  EPA is proposing numeric nutrient criteria for the following
parameters and geographic classifications in south Florida, for canals
classified as Class III waters under Florida law (Rule 62-302.400,
F.A.C.).  The proposed and alternative approaches described herein would
not apply for TP in canals within the Everglades Protection Area (EvPA)
since there is an existing TP criterion of 0.010 mg/L that currently
applies to the marshes and adjacent canals within the EvPA (Rule
62-302.540, F.A.C.).  

	Chlorophyll a

(µg/L) a	Total Phosphorus (TP)

(mg/L) a, b	Total Nitrogen (TN)

(mg/L) a

Canals	4.0 	0.042 	1.6 

a Concentration values are based on annual geometric mean not to be
surpassed more than once in a three-year period.  In addition, the
long-term average of annual geometric mean values shall not surpass the
listed concentration values.  (Duration = annual; Frequency = not to be
surpassed more than once in a three-year period or as a long-term
average).

b Applies to all canals within the Florida Department of Environmental
Protection’s South Florida bioregion, with the exception of canals
within the Everglades Protection Area (EvPA) where the TP criterion of
0.010 mg/L currently applies.

The following sections detail the methodology EPA used to develop the
proposed numeric nutrient criteria for canals in south Florida, and
request comment on the proposed criteria and their derivation.  In
addition, EPA is providing details of two alternative options for
deriving canal criteria values that EPA considered and is soliciting
comments on these alternatives.

(2)  Methodology for Deriving EPA’s Proposed Criteria for South
Florida Canals

	Based on the available information for canals, EPA determined that the
most scientifically sound way to derive protective numeric nutrient
criteria for south Florida’s canals is to use a similar approach to
what EPA used to derive numeric nutrient criteria for streams.  That is,
EPA chose a nutrient concentration distribution-based approach using
data from only those canals that have been determined to support the
applicable designated use.  EPA used existing water quality assessments
and identified canals that have been determined to be impaired for
nutrients.  Data for those canals were excluded from the larger data set
in order to create a set of data representing canals attaining the
designated use of aquatic life, according to FDEP’s assessment
decisions.  For further information, please refer to EPA’s TSD for
Florida’s Inland Waters, Chapter 4:  Methodology for Deriving U.S.
EPA’s Proposed Criteria for Canals.

	(a)  Derivation of Proposed Numeric Nutrient Criteria for South Florida
Canals

EPA derived numeric nutrient criteria for south Florida canals for two
causal variables, TN and TP, and one response variable, chlorophyll a. 
In contrast to EPA’s proposed criteria for Florida’s streams, EPA
concluded that there was a sufficient scientific basis for a chlorophyll
a criterion for south Florida canals.  EPA considered chlorophyll a to
be an appropriate indicator of nutrient impairment in canals on the
basis of the observed seasonal flow regimes, particularly during the
relatively drier winter months when flows are relatively lower and canal
water residence time is relatively higher (as compared to wetter, summer
months).  Furthermore, EPA found evidence that canals are susceptible to
impairment due to excessive chlorophyll a based on the number of canals
on Florida’s CWA section 303(d) list with chlorophyll a cited as the
parameter of concern.  EPA analyzed the range of chlorophyll a
concentrations in canals and found that 12% of chlorophyll a
concentration observations occurred at 10 g/L or higher and 5% of
chlorophyll a concentration observations occurred at 20 g/L or
higher.  As a point of reference, Florida has chlorophyll a thresholds
of 20 as the numeric interpretations of its narrative nutrient criteria
for streams and 11 g/L for estuaries/open coastal waters,
respectively, in its Impaired Waters Rule (IWR) (Rules 62-303.351 and
62-303.353, F.A.C.).  Thus, EPA included chlorophyll a as a nutrient
criterion to protect canal aquatic life designated uses from an
unacceptable biological response to excess nutrients.

	EPA employed a statistical distribution approach for deriving numeric
nutrient criteria for south Florida canals.  Specifically, EPA computed
statistical distributions and descriptive statistics (e.g., quartiles,
mean, standard deviation) of TN, TP, and chlorophyll a concentrations
from data derived at canal sites across south Florida that are not on
the impaired waters list for Florida.  EPA has determined that the
criteria derived from a distribution of canal data from canals with no
evidence of nutrient impairment are appropriate and protective of
designated uses.   

	 As described in detail in Section III.C(2)(c), EPA concluded that the
75th percentiles of the respective TN, TP, and chlorophyll a
distributions would yield values that would ensure that aquatic life
designated uses would be protected in south Florida canals.  A
reasonable choice is one that lies just above the vast majority of the
population.  The 75th percentile represents such a point on the
distribution of TN, TP, and chlorophyll a values.

	(b)  Other Data and Analyses Conducted and Considered by EPA in the
Derivation of Proposed Numeric Nutrient Criteria for South Florida
Canals

EPA undertook extensive analyses and considered a variety of data and
methods for deriving numeric nutrient criteria for Florida’s canals. 
Although EPA derived the proposed values based on the approach outlined
in the section above, EPA also factored into its decision-making process
the results of these other analyses as additional lines of evidence.  

One line of additional evidence is based on an evaluation of the
stressor-response relationship between chlorophyll a levels in canals
and TN and TP levels using a variety of statistical tools.  A second
line of evidence is based on a consideration of the distribution of
chlorophyll a measurements, TN measurements, and TP measurements from
all canals, impaired and not impaired.  Nutrient concentrations at the
lower end of these distributions were compared to the concentration that
the stressor-response analysis determined to be associated with canals
with no evidence of nutrient impairment.  The third line of evidence is
based on a consideration of the distribution of chlorophyll a, TN, and
TP values from only those canals considered to be minimally impacted by
nutrient-related pollution.  EPA considered each of these lines of
evidence in deriving the numeric nutrient criteria for canals.

Because soil or substrate type at the bottom of a canal can influence
the nutrient cycling and relationships between the observed biological
response and the TP and TN levels in canals, EPA used data on soil types
in south Florida along with knowledge of the Everglades Agricultural
Area (EAA) and the Everglades Protection Area (EvPA) to subdivide the
canal areas for criteria derivation.  Thus the first step in these other
analyses was to group canals and canal data by soil type.  The four
groupings consist of histosol and entisol soils of the EAA; histosol and
entisol soils of the EvPA; spodosol and alfisol soils and areas west of
the EvPA and EAA (hereafter, West Coast); and spodosol, entisol and
alfisol soils and areas east of the EvPA and EAA (hereafter East Coast).

EPA then sorted canal data (provided by FDEP, Miami-Dade County, and the
South Florida Water Management District) into the four canal groupings. 
EPA screened the data to ensure the exclusion of the following: 1) sites
without relevant data (e.g., nitrogen, phosphorus, chlorophyll a), 2)
sites influenced by marine waters, 3) sites within Class IV canals or
Lake Okeechobee, 4) data not originating within a canal,  5) data with
questionable units, and 6) outlier data.  Data were organized by canal
regions and year.  Each site occurring near the border of a region
and/or WBID was visually inspected using geographic information system
(GIS) tools to ensure the correct placement of those sites.  Local
experts were also consulted by EPA.  EPA analyzed the resulting
regionalized data using statistical distribution and regression
analyses.  EPA undertook its additional analyses using these canal (and
data) groupings.

EPA’s analysis of the distribution of chlorophyll a values in each of
the four groupings of canals (using data from impaired and unimpaired
sites) indicated that the lower percentile (i.e., 25th percentile)
ranged from 1.9 to 2.2 µg/L for chlorophyll a in the EvPA, West Coast,
and East Coast, and was 6.3 µg/L for the EAA.  EPA’s analysis of the
distribution of TN values in each of the four groupings of canals
indicated that the lower percentile (i.e., 25th percentile) ranged from
0.8 to 1.4 mg/L for the EvPA, West Coast, and East Coast and was 2.1mg/L
for the EAA.  EPA’s analysis of the distribution of TP values in each
of the four groupings of canals indicated that the lower percentile
(i.e., 25th percentile) ranged from 0.013 to 0.023 mg/L for the EvPA,
West Coast, and East Coast and was 0.048 mg/L for the EAA canals.  

In an effort to consider chlorophyll a, TN, and TP values in canals
minimally impacted by nutrient pollution, EPA identified canal sites
surrounded by the EvPA in the east and the Big Cypress National Preserve
in the west and considered the distribution of chlorophyll a, TN and TP
values for these sites.  Although EPA acknowledges that these sites have
not been thoroughly vetted for biological condition, EPA believes that
because they are remote and surrounded by wetlands, that these canal
sites represent sites with the lowest impact from human activities.  The
upper percentile values (i.e., the 75th percentile) from the
distributions of chlorophyll a, TN and TP values for these lower impact
sites are 3.4 µg/L for chlorophyll a, 1.3 mg/L for TN and 0.018 mg/L
for TP.

	When considering the results of these additional analyses and comparing
these results to the outcome of EPA’s analysis of TN, TP, and
chlorophyll a concentrations from data derived at canal sites across
south Florida that are not on the impaired waters list for Florida, it
is clear that EPA’s proposed criteria for canals are similar to those
derived from alternative approaches and therefore, represent a
reasonable integration of these multiple lines of evidence.  For further
information, please refer to EPA’s TSD for Florida’s Inland Waters,
Chapter 4:  Methodology for Deriving U.S. EPA’s Proposed Criteria for
Canals.

(c)  Proposed Criteria:  Duration and Frequency

Aquatic life water quality criteria contain three components: magnitude,
duration, and frequency.  For the TN and TP numeric criteria for
canals, the derivation of the criterion-magnitude values is described
above and these values are provided in the table in Section III.E(1). 
The criterion-duration for this magnitude (or averaging period) is
specified in footnote a of the canals criteria table as an annual
geometric mean.  EPA is proposing two expressions of allowable
frequency, both of which are to be met.  First, EPA proposes a
no-more-than-one-in-three-years excursion frequency for the annual
geometric mean criteria for canals.  Second, EPA proposes that the
long-term arithmetic average of annual geometric means not exceed the
criterion-magnitude concentration.  EPA anticipates that Florida will
use their standard assessment periods as specified in Rule 62-303,
F.A.C. (Impaired Waters Rule) to implement this second provision.  
These proposed duration and frequency components of the criteria are
consistent with the data set used to derive the criteria that contained
data from multiple years of record, all seasons, and a variety of
hydrologic conditions.  EPA has determined that this frequency of
excursions should not result in unacceptable effects on aquatic life as
it will allow the canal aquatic system enough time to recover from an
occasionally elevated year of nutrient loadings.  The Agency requests
comment on these proposed duration and frequency expressions of the
canal numeric nutrient criteria.

) a criterion-frequency expressed as meeting the allowable magnitude and
duration as a long-term average only.  EPA further requests comment on
whether an expression of the criteria in terms of an arithmetic average
of annual geometric mean values based on rolling three-year periods of
time would also be protective of the designated use.

  (3)  Request for Comment and Data on Proposed Approach

EPA believes the proposed numeric nutrient criteria for south Florida
canals in this rule are protective of the designated uses, consistent
with CWA section 303(c)(2)(A) and 40 CFR 131.11(a)(1).  EPA solicits
comment on the approaches taken by the Agency in this proposal, the data
underlying those approaches, and the proposed criteria.  EPA is seeking
other pertinent scientific data and information that are readily
available related to nutrient concentrations or nutrient responses in
Class III canals in south Florida.  

EPA is soliciting comment specifically on the selection of criteria
parameters for TN, TP, and chlorophyll a; development of criteria for
Class III canals across south Florida; and the conclusion that the
proposed criteria for Class III canals are protective of designated uses
and adequately account for the spatial and temporal variability of
nutrients.  

(4)  Alternative Approaches for Comment

EPA is requesting comments and views on the advantages and disadvantages
of alternative approaches to deriving protective criteria for south
Florida canals.  These approaches include: 1) a stressor-response
approach (based on data from all canals or canals grouped by soil type),
and 2) methodologies that have been employed to develop nutrient targets
in an EPA-proposed TMDL for dissolved oxygen and nutrients.   

As previously described in Section III.E(2)(b), EPA considered the
underlying soil type of south Florida canals as a possible basis for
geographic classification.  Analysis of the underlying soil types,
indicated by STATSGO, led EPA to identify the following four canal
regions: Everglades Agricultural Area (EAA) comprised of histosol and
entisol soils, EvPA comprised of histosol and entisol soils, areas west
of the EvPA and EAA, or West Coast, comprised of spodosol and alfisol
soils, and areas east of the EvPA and EAA, or East Coast, comprised of
spodosol, entisol, and alfisol soils.  

Subsequent to classification, the proposed statistical
distribution-based approach  or the alternatives to the proposed
approach described in the following sections could be used to derive
numeric nutrient criteria by canal region for any or all of the proposed
criteria (i.e., TN, TP, and chlorophyll a) provided that sufficient data
are available.  

	(a)  Stressor-Response Approach

	EPA considered two statistical analyses for assessing the
stressor-response relationship between nutrients and biological
response.  In contrast to the proposed option, which included only data
from sites with no evidence of nutrient impairment, the
stressor-response analyses included all data regardless of whether sites
were associated with WBIDs that have been determined to be impaired. 
EPA conducted linear and quantile regression analyses between
chlorophyll a, TP, and TN on a regional and aggregated regional basis. 
EPA used the linear regression model as a statistical tool to predict
the chlorophyll a response based on matched chlorophyll a and TN and TP
data.  Similarly, quantile regression was used to analyze the matched
nutrient and chlorophyll a data.  In this application, quantile
regression was used to predict the 90th percentile of the distribution
of chlorophyll a concentration at a given concentration of TN or TP.  

	To apply either statistical approach for developing numeric nutrient
criteria for TP or TN, EPA would need to identify the concentration of
chlorophyll a that would be protective of the designated use for these
canal systems.  One approach would be to use EPA’s proposed
chlorophyll a criterion of 4.0 µg/L for canals to derive the TN and TP
criteria from stressor-response relationships. 	 	

(b)  Calculation of TP Criteria for the Everglades Agricultural Area
(EAA) Using a Downstream Protection Approach

EPA considered using the methodologies described in the EPA-proposed
TMDL for dissolved oxygen and nutrients to develop numeric nutrient
criteria, specifically TP, for portions of the EAA.  These methodologies
are described in the TMDL in Section 4.2.2.1 of the TMDL document,
“Approach #1: Estimate STA inflow loads resulting in WQS in downstream
waters”, and Section 4.2.2.2 of the TMDL document, “Approach #2:
Simple modeling approach.”  The first approach takes into account the
downstream criterion of the EvPA and the performance of the stormwater
treatment areas (STAs).  Based on these considerations, inflowing TP
concentrations within the EAA to the STAs were derived to meet the
downstream EvPA TP criterion of 0.010 mg/L.  The second approach used a
model that extrapolated natural background TP concentrations, based on
land use changes, for specific WBIDs within the EAA.  These approaches
could support the derivation of numeric nutrient criteria for TP within
the EAA region.  Approach #1 would result in a TP concentration of 0.10
mg/L, while Approach #2 would result in a TP concentration of 0.087
mg/L.

(5)  Request for Comment and Data on Alternative Approaches

	The alternatives for Class III south Florida canal criteria in this
proposed rule represent alternative approaches given the availability of
data in the State of Florida to date and are consistent with the
requirements of both the CWA and EPA’s implementing regulations.  EPA
is soliciting comment on the alternative approaches considered by the
Agency in this proposal, the data underlying those approaches, and the
proposed alternatives themselves, including criteria expressed as an
upper percentile maxima not to be exceeded more than 10% of the time in
one year, similar to those discussed for lakes.  For further information
on the upper percentile criteria for canals, refer to EPA’s TSD on
Florida’s Inland Waters, Chapter 4:  Methodology for Deriving U.S.
EPA’s Proposed Criteria for Canals.  EPA is seeking other pertinent
data and information related to nutrient concentrations or nutrient
responses in Class III canals in south Florida.  

F.  Comparison Between EPA’s and Florida DEP’s Proposed Numeric
Nutrient Criteria for Florida’s Lakes and Flowing Waters

To date, Florida has invested significant resources in its statewide
nutrient criteria effort, and has made substantial progress toward
developing numeric nutrient criteria.  For several years, FDEP has been
actively working with EPA on the development of numeric nutrient
criteria and EPA has worked extensively with FDEP on data interpretation
and technical analyses for developing EPA’s recommended numeric
nutrient criteria proposed in this rulemaking.  

On January 14, 2009, EPA formally determined that numeric nutrient
criteria were necessary to protect Florida’s lakes and flowing waters
and should be developed by January 14, 2010.  FDEP, independently from
EPA, initiated its own State rulemaking process to adopt numeric
nutrient water quality criteria protective of Florida’s lakes and
flowing waters.  According to FDEP, the State initiated its rulemaking
process to facilitate the assessment of designated use attainment for
Florida’s waters and to provide a better means to protect its waters
from the adverse effects of nutrient over-enrichment.  Florida
established a technical advisory committee, which met over a number of
years, to help develop its proposed numeric nutrient criteria.  The
State also held several public workshops to solicit comment on the draft
WQS.  While FDEP was progressing with its State rulemaking, EPA moved
forward to develop Federal numeric nutrient criteria for Florida’s
lakes and flowing waters, consistent with EPA’s January 14, 2009
determination and based on the best available science.

Most recently, in July 2009, FDEP solicited public comment on its
proposed numeric nutrient criteria for lakes and flowing waters.  In
October 2009, FDEP decided not to bring the draft criteria before the
Florida Environmental Regulation Commission (ERC), as had been
previously scheduled.  FDEP did not make any final decisions as to
whether it might be appropriate to ask the ERC to adopt the criteria or
some portions of the criteria at a later date.  

As described in Section III., EPA is proposing numeric nutrient criteria
for the following four water body types: lakes, streams, springs and
clear streams, and canals in south Florida.  Given that FDEP has made
its proposed numeric nutrient criteria available to the public via its
Web site (  HYPERLINK
"http://www.dep.state.fl.us/water/wqssp/nutrients/index.htm" 
http://www.dep.state.fl.us/water/wqssp/nutrients/index.htm ), it is
worth providing a comparative overview between the criteria and
approaches that EPA is proposing in this rulemaking and the criteria and
approaches FDEP had initially proposed.  Both EPA and FDEP developed
numeric criteria recognizing the hydrologic and spatial variability of
nutrients in Florida’s lakes and flowing waters.  As FDEP indicated on
its Web site, FDEP’s preferred approach is to develop cause and effect
relationships between nutrients and valued ecological attributes, and to
establish nutrient criteria based on those cause and effect
relationships that ensure that the designated uses of Florida’s waters
are protected and maintained.  As described in EPA’s guidance, EPA
also recommends this approach when scientifically defensible data are
available.  Where cause and effect relationships could not be
demonstrated, however, both FDEP and EPA relied on a distribution-based
approach to derive numeric nutrient criteria protective of applicable
designated uses.

To set numeric nutrient criteria for lakes, EPA, like FDEP, is proposing
a classification scheme using color and alkalinity based upon
substantial data that show that lake color and alkalinity play an
important role in the degree to which TN and TP concentrations result in
a biological response such as elevated chlorophyll a levels.  EPA and
FDEP both found that correlations between nutrients and response
parameters were sufficiently robust to use for criteria development in
Florida’s lakes.  EPA is proposing the same chlorophyll a criteria for
colored lakes and clear alkaline lakes as FDEP proposed, however, EPA is
proposing a lower chlorophyll a criterion for clear acidic lakes.  EPA,
like FDEP, is also proposing an accompanying supplementary analytical
approach that Florida can use to adjust general TN and TP lake criteria
within a certain range where sufficient data on long-term ambient TN and
TP levels are available to demonstrate that protective chlorophyll a
criteria for a specific lake will still be maintained and attainment of
the designated use will be assured.  

Lake Class	EPA Proposed Criteria	Florida Proposed Criteria

	Chl a, µg/L	TN, mg/L	TP, mg/L	Chl a, µg/L	TN,

mg/L	TP,

mg/L

Colored Lakes                > 40 PCU	

20 

	

1.23-2.25	

0.050-0.157	20	1.23-2.25	0.05-0.157

Clear Lakes, Alkaline

≤ 40 PCU and 

> 50 mg/L CaCO3	

20 

	

1.00-1.81	

0.030-0.087	20	1.00-1.81	0.03-0.087

Clear Lakes, Acidic

≤ 40 PCU and 

≤ 50 mg/L CaCO3 	

6 

	

0.500-0.900	

0.010-0.030	9	0.85-1.14	0.015-0.043



To set numeric nutrient criteria for streams, FDEP recommended a
statistical distribution approach based on “benchmark sites”
identified in five nutrient regions (five regions for TP and two regions
for TN), given that FDEP determined cause and effect relationships to be
insufficiently robust for establishing numeric thresholds.  FDEP relied
on the use of a narrative criterion to protect downstream waters.  EPA
also concluded that a scientifically defensible cause and effect
relationship could not be demonstrated with the available data and that
a distribution-based approach was most appropriate.  However, EPA
considered an alternative approach that evaluated a combination of
biological information and data on the distribution of nutrients in a
substantial number of healthy stream systems to derive scientifically
sound TN and TP criteria for streams.  

The respective criteria for instream protection of Florida’s streams
derived using EPA’s recommended approach and FDEP’s recommended
approach are comparable.

EPA Nutrient Watershed Regions	EPA Proposed Instream Criteria	Florida
Nutrient Watershed Regions	FL Proposed Instream Criteria

	TN (mg/L)	TP (mg/L)

TN (mg/L)	TP (mg/L)

Panhandle	0.824	0.043	Panhandle	0.820	0.069

Bone Valley	1.798	0.739	Bone Valley	

1.730	0.415

Peninsula	1.205	0.107	Peninsula

0.116

North Central	1.479	0.359	North Central

0.322

	Northeast

0.101



cases where a stream first flows into a lake and then flows out from the
lake into another lake or estuary, the portion of the stream that exits
the lakes needs to comply with the downstream protection values for
estuaries, assuming that is the terminal reach.

EPA is proposing the same nitrate-nitrite causal variable criterion for
springs and clear streams as proposed by FDEP.  For canals in south
Florida, EPA is proposing a statistical distribution approach based on
sites meeting designated uses with respect to nutrients (i.e., not
identified as impaired by FDEP) identified in four canal regions.  FDEP
did not propose numeric nutrient criteria for canals in its rulemaking. 


Please refer to Section IV. Under What Conditions Will Florida Be
Removed From a Final Rule for information on how State-adopted and
EPA-approved WQS could become effective under the CWA 303(c).  

G.  Applicability of Criteria When Final  

EPA’s proposed numeric nutrient criteria for Florida’s lakes and
flowing waters will be effective for CWA purposes 60 days after
publication of final criteria and will apply in addition to any other
existing CWA-effective criteria for Class I or Class III waters already
adopted by the State and submitted to EPA (and for those adopted after
May 30, 2000, approved by EPA).  EPA requests comment on this proposed
effective date.  FDEP establishes its designated uses through a system
of classes and Florida waters are designated into one of several
different classes.  Class III waters provide for healthy aquatic life
and safe recreational use.  Class I waters include all the protection of
designated uses provided for Class III waters, and also include
protection for designated uses related to drinking water supply.  Class
I and III waters, together with Class II waters that are designated for
shellfish propagation or harvesting, comprise the set of Florida waters
that meet the goals articulated in section 101(a)(2) of the CWA and the
waters for which EPA is proposing criteria.  Pursuant to the schedule
set out in EPA’s January 2009 determination, Class II waters will be
addressed in rulemaking in January 2011.  For water bodies designated as
Class I and Class III predominately fresh waters, any final EPA numeric
nutrient criteria will be applicable CWA water quality criteria for
purposes of implementing CWA programs including permitting under the
NPDES program, as well as monitoring and assessment based on applicable
CWA WQS and establishment of TMDLs.

The proposed criteria in this rule, if and when finalized, would be
subject to Florida’s general rules of applicability in the same way
and to the same extent as are other State-adopted and/or
federally-promulgated criteria for Florida waters.  See proposed 40 CFR
131.43(d)(2).  For example, Florida regulations at Rule 62-4.244, F.A.C.
authorize mixing zones when deriving effluent limitations for discharges
of pollutants to Florida waters.  These regulations would apply to
permit limitations implementing the criteria in this rule.  This
proposal includes some additional language on mixing zone requirements
to help guide Florida in developing and applying mixing zone policies
for nutrient criteria.  Specifically, EPA provides that the criteria
apply at the appropriate locations within or at the boundary of the
mixing zones; otherwise the criteria apply throughout the water body
including at the point of discharge into the water body.  See proposed
40 CFR 131.43(d)(2)(i).  Likewise, EPA includes proposed regulatory
language specifying that Florida use an appropriate design flow
condition, one that matches the proposed criteria duration and
frequency, for use in deriving permit limits and establishing wasteload
and load allocations for a TMDL.  See proposed 40 CFR 131.43(d)(2)(ii). 


In addition, EPA recognizes that Florida regulations include provisions
for assessing whether waters should be included on the list of impaired
waters pursuant to section 303(d) of the CWA.  See Rule 62-303, F.A.C. 
The Impaired Waters Rule, or IWR, sets out a methodology to identify
waters that do not meet the State’s WQS and, therefore, are required
to be included on CWA section 303(d) lists.  The current IWR does not
address how to assess waters based on EPA’s proposed numeric nutrient
criteria.  The numeric nutrient criteria in any final rule,
nevertheless, will be applicable WQS that must be addressed when the
State assesses waters pursuant to CWA section 303(d).  

EPA proposes language in this rulemaking that acknowledges the IWR
procedures and their function, specifying that those procedures apply
where they are consistent with the level of protection provided by the
proposed criteria.  See proposed 40 CFR 131.43(d)(2)(iii).  Some IWR
provisions, which describe the sufficiency or reliability of information
necessary for the State to make an attainment decision, do not change
the level of protection afforded Florida waters.  These are beyond the
scope of WQS under CWA section 303(c).  Other provisions of the IWR may
provide some additional detail relevant to assessment, such as the
number of years worth of data assessed for a particular listing cycle
submittal, which should be consistent with the level of protection
provided with the proposed criteria.  Should any IWR provisions apply a
different level of protection than the Federal criteria when making
attainment decisions based on proposed criteria, EPA would expect to
take appropriate action to ensure that the States’ CWA section 303(d)
list of impaired waters includes all waters not attaining the Federal
criteria.

IV. Under What Conditions Will Federal Standards Be Either Not Finalized
or Withdrawn?

	Under the CWA, Congress gave states primary responsibility for
developing and adopting WQS for their navigable waters.  See CWA section
303(a)-(c).  Although EPA is proposing numeric nutrient criteria for
Florida’s lakes and flowing waters, Florida continues to have the
option to adopt and submit to EPA numeric nutrient criteria for the
State’s lakes and flowing waters consistent with CWA section 303(c)
and implementing regulations at 40 CFR part 131.  Consistent with CWA
section 303(c)(4), if Florida adopts and submits numeric nutrient
criteria and EPA approves such criteria as fully satisfying the CWA
before publication of the final rulemaking, EPA will not proceed with
the final rulemaking for those waters for which EPA approves Florida’s
criteria. 

	Pursuant to 40 CFR 131.21(c), if EPA does finalize this proposed rule,
the EPA promulgated WQS would be applicable WQS for purposes of the CWA
until EPA withdraws the federally-promulgated standard.  Withdrawing the
Federal standards for the State of Florida would require rulemaking by
EPA pursuant to the requirements of the Administrative Procedure Act (5
U.S.C.551 et seq.).  EPA would undertake such a rulemaking to withdraw
the Federal criteria only if and when Florida adopts and EPA approves
numeric nutrient criteria that fully meet the requirements of section
303(c) of the CWA and EPA’s implementing regulations at 40 CFR part
131.   

If EPA finalizes the proposed restoration standard provision (discussed
in Section VI below), that provision would be adopted into regulation
and would allow Florida to establish interim designated uses with
associated water quality criteria, while maintaining the full CWA
section 101(a)(2) aquatic life and/or recreational designated use of the
water as the ultimate goal.   EPA may proceed to promulgate numeric
nutrient criteria for Florida together with or separate from EPA’s
proposed restoration standards provision, depending on the comments
received on that proposal.

V. Alternative Regulatory Approaches and Implementation Mechanisms 

A. Designating Uses  

Under CWA section 303(c), states shall adopt designated uses after
taking “into consideration the use and value of water for public water
supplies, protection and propagation of fish, shellfish, and wildlife,
recreation in and on the water, agricultural, industrial and other
purposes including navigation.”  Designated uses “shall be such as
to protect the public health or welfare, enhance the quality of water
and serve the purposes of [the CWA].”  CWA section 303(c)(1).  EPA’s
regulation at 40 CFR 131.3(f) defines “designated uses” as “those
uses specified in water quality standards for each water body or segment
whether or not they are being attained.”   Under 40 CFR 131.10,
EPA’s regulation addressing “Designation of uses”, a “use” is
a particular function of, or activity in, waters of the United States
that requires a specific level of water quality to support it.  In other
words, designated uses are a state’s concise statements of its
management objectives and expectations for each of the individual
surface waters under its jurisdiction.  

In the context of designating uses, states often work with stakeholders
to identify a collective goal for their waters that the state intends to
strive for as it manages water quality.  States may evaluate the
attainability of these goals and expectations to ensure they have
designated appropriate uses (see 40 CFR 131.10(g)).  Consistent with CWA
sections 101(a)(2) and 303(c)(2)(A), 40 CFR 131.2 provides that states
“should, wherever attainable, provide water quality for the protection
and propagation of fish, shellfish, and wildlife and for recreation in
and on the water.”  Where states do not designate those uses, or
remove those uses, they must demonstrate that such uses are not
attainable consistent with 40 CFR 131.10(g).  States may determine,
based on a UAA, that attaining a designated use is not feasible and
propose to EPA to change the use and/or the associated pollutant
criteria to something that is attainable.  This action to change a
designated use must be completed in accordance with EPA regulations (see
40 CFR 131.10(g) and (h)).   

Within the framework described above, states have discretion in
designating uses.  EPA’s proposed numeric nutrient criteria for lakes
and flowing waters would apply to those waters designated by FDEP as
Class I (Potable Water Supplies) or Class III (Recreation, Propagation
and Maintenance of a Healthy, Well-Balanced Population of Fish and
Wildlife).  If Florida removes the Class I or Class III designated use
for any particular water body ultimately affected by this rule, and EPA
finds that removal to be consistent with CWA section 303(c) and the
regulations at 40 CFR part 131, then the federally-promulgated numeric
nutrient criteria would not apply to that water body.  Instead, the
nutrient criteria associated with the newly designated use would apply
to that water body.  FDEP has recently restarted an effort to refine the
State’s current designated use classifications.  As this process
continues, EPA expects that the State may find some instances where this
particular discussion may be relevant and useful as the refinement of
uses is investigated further. 

	Where states can identify multiple waters with similar characteristics
and constraints on attainability, EPA interprets the Federal WQS
regulation to allow states to conduct a “categorical” use
attainability analysis (UAA) under 40 CFR 131.10(g) for such waters. 
This approach may reduce data collection needs, allowing a single
analysis to represent many sites.  To use such an approach, however, the
State would need to have enough information about each particular site
to reliably place each site into a broader category and Florida would
need to specifically identify each site covered by the analysis. 
Florida may wish to consider such an approach for certain waters, such
as a network of canals with similar hydrologic and morphological
characteristics, which can be characterized as a group and where the
necessary level of protection may differ substantially from other lakes
or flowing waters within the State.

B.  Variances  

A variance is a temporary modification to the designated use and
associated water quality criteria that would otherwise apply to the
receiving water.  A variance is based on a UAA and identifies the
highest attainable use and associated criteria during the variance
period.  Typically, variances are time-limited (e.g., three years), but
renewable.  Modifying the designated use for a particular water through
a variance process allows a state to limit the applicability of a
specific criterion to that water and to identify an alternative
designated use and associated criteria to be met during the term of the
variance.  A variance should be used instead of removal of a use where
the state believes the standard can be attained in a short period of
time.  By maintaining the standard rather than changing it, the state
ensures that further progress will be made in improving water quality
and attaining the standard.  A variance may be written to address a
specified geographical coverage, a specified pollutant or pollutants,
and/or a specified pollutant source.  All other applicable WQS not
specifically modified by the variance would remain applicable (e.g., any
other criteria adopted to protect the designated use).  State variance
procedures, as part of state WQS, must be consistent with the
substantive requirements of 40 CFR part 131.  A variance allows, among
other things, NPDES permits to be written such that reasonable progress
is made toward attaining the underlying standards for affected waters
without violating section 402(a)(l) of the Act, which requires that
NPDES permits must meet the applicable WQS.  See also CWA section
301(b)(1)(C).  

For purposes of this proposal, EPA is proposing criteria that apply to
use designations that Florida has already established.  EPA believes
that the State has sufficient authority to use its adopted and
EPA-approved variance procedures with respect to modification of their
Class I or Class III uses as it pertains to any federally-promulgated
nutrient criteria.  For this reason, EPA is not proposing a Federal
variance procedure.    

C. Site-specific Criteria  

A site-specific criterion is an alternative value to a statewide, or
otherwise applicable, water quality criterion that meets the regulatory
test of protecting the designated use and having a basis in sound
science, but is tailored to account for site-specific conditions. 
Site-specific alternative criteria (SSAC) may be more or less stringent
than the otherwise applicable criteria.  In either case, because the
SSAC must protect the same designated use and must be based on sound
science (i.e., meet the requirement of 40 CFR 131.11(a)), there is no
need to modify the designated use or conduct a UAA.  SSAC may be
appropriate when additional scientific consideration can bring added
precision or accuracy to express the necessary level or concentration of
a water quality parameter that is protective of the designated use.

	Florida has adopted procedures for developing and adopting SSAC in its
WQS regulations at Florida Administrative Code (Rule 62-302.800,
F.A.C.).  Florida’s Type I SSAC procedure is intended to address
site-specific situations where a particular water body cannot meet the
applicable water quality criterion because of natural conditions.  See
Rule 62-302.800(1).  Florida’s Type II SSAC procedure is intended to
address site-specific situations other than natural conditions where it
can be established that an alternative criterion from the broadly
applicable criteria established by the State is protective of a
water’s designated uses.  See Rule 62-302.800(1), F.A.C.  Florida’s
Type II procedure is primarily intended to address toxics but there is
no limitation in its use for other parameters, except for certain
parameters identified by FDEP, including nutrients.  See Rule
62-302.800(2).  Florida’s regulations currently do not allow use of
Type II procedures for nutrient criteria development because the State
currently does not have broadly applicable numeric nutrient criteria for
State waters.  Rather, the current narrative criterion for nutrients is
implemented by translating it into numeric loads or concentrations on a
case-by-case basis.  EPA’s proposed rule would not affect Florida’s
Type I or Type II SSAC procedures.

PA believes that there would be benefit in establishing a specific
procedure in the Federal rule for EPA adoption of SSAC.  In this
rulemaking, EPA is proposing a procedure whereby the State could develop
a SSAC and submit the SSAC to EPA with supporting documentation for
EPA’s consideration.  The State SSAC could be developed under either
the State SSAC procedures or EPA technical processes as set out more
fully below.  EPA elected to propose this approach because this
procedure maintains the State in a primary decision-making role
regarding development of SSAC for State waters.  The procedure that EPA
is proposing would also allow the State to submit a proposed SSAC to EPA
without having to first go through the State’s rulemaking process.

The proposed procedure would provide that EPA could determine that the
SSAC should apply in lieu of the generally applicable criteria
promulgated pursuant to this rule.  The proposed procedures provide that
EPA would solicit public comment on its determination.  Because EPA’s
rule would establish this procedure, implementation of this procedure
would not require withdrawal of federally-promulgated criteria for
affected water bodies in order for the SSAC to be effective for purposes
of the CWA.  EPA has promulgated similar procedures for EPA granting of
variances and SSACs in other federally-promulgated WQS.

EPA also considered technical processes necessary to develop protective
numeric nutrient criteria on a site-specific basis.  To complete a
thorough and successful analysis to develop numeric nutrient SSAC, EPA
expects the State to conduct, or direct applicants to the State to
conduct, a variety of supporting analyses.  For the instream protection
value (IPV) for streams, this analysis would, for example, consist of
examining both indicators of longer-term response to multiple stressors
such as benthic macroinvertebrate health, as determined by Florida’s
Stream Condition Index (SCI) and indicators of shorter-term response
specific to nutrients, such as periphyton algal thickness or chlorophyll
a levels.  The former analysis will help address concerns that a
potential nutrient effect is masked by other stressors (such as
turbidity which can limit light penetration and primary production
response to nutrient response), whereas the latter analysis will help
address concerns that a potential nutrient effect is lagging in time and
has not yet manifested itself.  Indicators of shorter-term response
generally would not be expected to exhibit a lag time.

It will also be important to examine a stream system on a watershed
basis to ensure that a SSAC established for one segment does not result
in adverse effects in nearby segments.  For example, a shaded,
relatively swift flowing segment may open up to a shallow, slow moving,
open canopy segment that is more vulnerable to adverse nutrient impacts.
 Empirical data analysis of multiple factors affecting the expression of
response to nutrients and mechanistic models of ecosystem processes can
assist in this type of analysis.  It will also be necessary to ensure
that a larger load allowed from an upstream segment as a result of a
SSAC does not compromise protection on a downstream segment that has not
been evaluated.  

The intent of this discussion is to illustrate a process that is
rigorous and based on sound scientific rationale, without being
inappropriately onerous to complete.  Corollary analyses for a lake,
spring or clear stream, or canal situation would need to be pursued for
a SSAC on those systems. 

n addition to the procedure that EPA is proposing, Florida always has
the option of submitting State-adopted SSAC as new or revised WQS to EPA
for review and approval under the CWA section 303(c).  There is no bar
to a state adopting new or revised WQS for waters covered by a
federally-promulgated WQS.  For any State-adopted SSAC that EPA approves
under section 303(c) of the Act, EPA would also have to complete federal
rulemaking to withdraw the Federal WQS for the affected water body
before the State SSAC would be the applicable WQS for the affected water
body for purposes of the Act.  As discussed above, Florida WQS
regulations currently do not authorize the State to adopt nutrient SSAC
except where natural conditions are outside the limits of broadly
applicable criteria established by the State (Rule 62-302.800, F.A.C.)

This proposed SSAC process would also not limit EPA’s authority to
promulgate SSAC in addition to those developed by the State under the
process described in this rule.  The proposed rule recognizes that EPA
always has the authority to promulgate through rulemaking SSAC for water
that are subject to federally-promulgated water quality criteria.

D. Compliance Schedules

A compliance schedule, or schedule of compliance, refers to “a
schedule of remedial measures included in a ‘permit,’ including an
enforceable sequence of interim requirements … leading to compliance
with the CWA and regulations.”  40 CFR 122.2.  In an NPDES permit,
WQBELs are effluent limits based on applicable WQS for a given pollutant
in a specific receiving water (See NPDES Permit Writers Manual,
EPA-833-B-96-003, December, 1996).  In addition, EPA regulations provide
that schedules of compliance are to require compliance “as soon as
possible.”   

he regulation provides, in part, for schedules providing for compliance
“as soon as sound engineering practices allow, but not later than any
applicable statutes or rule deadline”.   The complete text of the
Florida rules concerning compliance schedules is available at  
HYPERLINK "https://www.flrules.org/gateway/RuleNo.asp?ID=62-620.620" 
https://www.flrules.org/gateway/RuleNo.asp?ID=62-620.620 .  Florida is,
therefore, authorized to grant compliance schedules under its rule for
WQBELs based on federally-promulgated criteria. 

Proposed Restoration Water Quality Standards (WQS) Provision

	As described above, many of Florida’s waters do not meet the water
quality goals established by the State and envisioned by the CWA because
of excess amounts of nutrients.  In some cases, restoring these water
could take many years to achieve, especially where there is a large
difference between current water quality conditions and the nutrient
criteria levels necessary to protect aquatic life.  In such cases,
Florida may conclude that restoration programs will not result in waters
attaining their designated aquatic life use (and associated numeric
nutrient criteria) for a long period of time.

	EPA’s current regulations provide that a state may remove a
designated use if it meets certain requirements outlined at 40 CFR
131.10.  Under this provision, if the State demonstrates that a
designated use is not attainable it may conduct a use attainability
analysis (UAA) to revise the designated use to reflect the highest
attainable aquatic life use,   even though that use may not meet the CWA
section 101(a)(2) goal.  Another option that states use to address
situations for an individual discharger is a discharger-specific
variance.  Neither of these approaches may be optimal or appropriate
solutions if a state determines that certain waters cannot attain
aquatic life uses due to excess nutrient in the near-term.  	

	Based on numerous workshops, meetings, conversations and day-to-day
interactions with state environmental managers, EPA understands that
states interested in restoring impaired water may desire the ability to
express, in their WQS, successive time periods with incrementally more
stringent designated uses and criteria that ultimately result in a
designated use and criteria that reflect a CWA section 101(a)(2)
designated use.  Such an approach would allow the state and stakeholders
necessary time to take incremental steps to achieve interim WQS as they
move forward to ultimately attain a CWA section 101(a)(2) designated
use.  Some states have used variances to provide such time in their WQS.
 However, variances are typically time limited (e.g.,three years) and
discharger-specific and do not address the challenges of pursuing
reductions from a variety of sources across a watershed.  In addition,
Federal regulations are not explicit in requiring that states pursue
feasible (i.e. attainable) progress toward achieving the highest
attainable use when implementing a variance.  Variances also often lack
specific milestones and a transparent set of expectations for the
public, dischargers, and stakeholders.  

	EPA seeks comment on this approach to providing Florida with an
explicit regulatory mechanism for directing state efforts to achieve
incremental progress in a step-wise fashion, applicable to all sources,
as a part of its WQS.  The proposed regulatory mechanism described in
this section applies only to WQS for nutrients in Florida waters subject
to this proposed rule.  

	A “restoration water quality standard” under EPA’s proposed rule
would be a WQS that Florida could adopt for an impaired water.  Under
EPA’s proposal, the State would retain the current designated use as
the ultimate designated use (e.g. providing for eventual attainment of a
full CWA section 101(a)(2) designated use and the associated criteria). 
However, under the restoration standard approach proposed in this rule,
the State would also adopt interim less stringent designated uses and
criteria that would be the basis for enforceable permit requirements and
other control strategies during the prescribed timeframes.   These
interim uses could be no less stringent than an existing use as defined
in section 131.3, and would have to meet the requirements of
131.10(h)(2). The State would need to demonstrate that the interim uses
and criteria, as well as the timeframe, are based on a UAA evaluation of
what is attainable and by when.  These interim designated uses and
criteria and the applicable timeframes would all be incorporated into
the State WQS on a site-specific basis, as would be any other designated
use change or adoption of site-specific criteria.  

	For example, a restoration WQS for nutrients for an impaired Class I or
Class III colored lake in Florida may take the form of the following for
a lake whose current condition represents severely impaired aquatic life
with chlorophyll a = 40 mg/L, TN = 2.7 mg/L, and TP = 0.15 mg/L: 

Time		Chl a	TN	TP	Designated Use Description 

Year 0-5 	35	2.4	0.10	Moderately Impaired Aquatic Life

Year 6-10	25	1.45	0.06	Slightly Impaired Aquatic Life

Year 11 	20	1.2	0.05	Full Aquatic Life Use

	Including such revised interim designated uses and criteria within the
regulations could support efforts by Florida to formally establish
enforceable long-term plans for different watersheds or stream reaches
to attain the ultimate designated use and the associated criteria.  At
the same time, the State would be able to ensure that its WQS explicitly
reflect the attainable designated uses and water quality criteria to be
met at any given time, consistent with the CWA and implementing
regulations.  

	Restoration WQS would provide in the Federal regulations the framework
for authorizing the State of Florida to adopt restoration WQS for
nutrients, along with maintaining the availability of other tools (e.g.,
variances and compliance schedule provisions), which provide flexibility
regarding permitting individual dischargers.  Restoration WQS would
require a full public participation process to assure transparency as
well as the opportunity for different parties to work together, exchange
information and determine what is actually attainable within a
particular time frame.  Going through this process would provide Florida
with a transparent set of expectations to push its waters towards
restoration in a realistic yet verifiable manner.  

	In this notice, EPA proposes restoration WQS as a clear regulatory
pathway for the State of Florida to adjust the Class I and Class III
designated uses (and associated nutrient criteria) of waters impaired by
nutrients that is intended to promote active restoration, maintain
progressive improvement, and ensure accountability.  This approach would
provide the State of Florida with the flexibility to adopt revised
designated uses and criteria under a set of specific regulatory
requirements.   

	Under this proposal, the interim designated uses and criteria would be
the basis for NPDES permits during the applicable period reflecting the
fact that the restoration WQS introduces the critical element of time as
part of the complete WQS.   This is intended to allow imposition of the
maximum feasible point source controls and nonpoint source nutrient
reduction strategies to be phased in within the overall context of
restoration activities within the watershed.  By reflecting how it
expects the existing poor quality of its waters to incrementally improve
to achieve longer-term WQS goals, Florida could create the flexibility
to explore more innovative ways to reach the requirements of the next
phase, thus possibly reducing costs or allowing new approaches to
resolve complex technological issues, and maximizing transparency with
the public during each phase.  These waters, however, would still be
considered impaired for CWA assessment and listing purposes because the
ultimate designated use and criteria would be part of the restoration
WQS and would not yet be met.

	The restoration standards would be Florida WQS revisions that would go
through the process of first being adopted under State law and then
approved by EPA.  This proposal would include eight requirements for the
development of a restoration WQS for nutrients:  

It must be demonstrated that it is infeasible to attain the full CWA
section 101(a)(2)aquatic life designated use during the time periods
established for the restoration phases with a UAA based on one of the
factors at 40 CFR 131.10(g).  

The highest attainable designated use and numeric criteria that apply at
the termination of the restoration WQS (i.e., the ultimate long-term
designated use and numeric criteria to be achieved) must be specified
and this use is to include, at a minimum, uses that are consistent with
the CWA section 101(a)(2) uses. 

Interim restoration designated uses and numeric water quality criteria,
with each based on achieving the maximum feasible progress during the
applicable phase as determined in the UAA, must be established.

Specific time periods for each restoration phase must be established.
The length of each phase must be based on the UAA demonstration of when
interim uses can be attained on a case-specific basis.  Interim
restoration designated uses and numeric water quality criteria must
reflect the highest attainable use during the time period of the
restoration phase.  The sum of these times periods may not exceed twenty
years. 

The spatial extent to which the restoration WQS will apply (e.g., how
far downstream the restoration WQS would apply) must be specified.  EPA
notes the importance of continuing to meet the requirements for
protection of downstream WQS as expressed in section 40 CFR 131.10(b). 
Adopting restoration WQS upstream of another impaired water may mean the
State should also consider restoration WQS for the downstream water.

The regulatory requirements for public participation and EPA review and
approval whenever revising its WQS must continue to be met. 
Specifically, a restoration WQS may not include interim uses less
stringent than a use that is an “existing use” as defined in 131.3
or that do not meet the requirements of 131.10(h)(2). 

The State must include in its restoration WQS that if the water body
does not attain the interim designated use and numeric water quality
criteria at the end of any phase, the restoration WQS will no longer be
in effect and the designated use and criteria that was to become
effective at the end of the final restoration phase will become
immediately effective unless Florida adopts and EPA approves a different
revised designated use and criteria.

The State must provide that waters for which a restoration WQS is
adopted will be recognized as impaired for the purposes of listing
impaired waters under section 303(d) of the CWA until the final use is
attained.

	Under this proposal, EPA would require Florida to adopt the ultimate
highest attainable designated use and criteria along with multiple
phases reflecting the stepwise improvements in water quality between the
initial effective date and when they expect to meet the ultimate highest
attainable use as a single restoration WQS package.  As with any
revision to an aquatic life use, Florida would be required to
demonstrate that the ultimate highest attainable designated use cannot
be attained during the restoration period, based on one of the factors
at CFR 131.10(g)(1)-(6) (i.e., through a UAA).  EPA would review the WQS
and all supporting documents before approving the restoration WQS.  

At the beginning of the first restoration phase, the State would
identify current conditions and establish the principle that there can
be no further degradation.  WQS for the first restoration phase should
reflect the outcomes of all controls that can be implemented within the
first restoration phase.  Additionally, EPA expects that the interim
restoration designated use and numeric criteria that are attainable at
the end of the restoration phase apply at the beginning of each phase as
well as throughout the phase.  For each phase, the State would adopt
interim designated uses and numeric water quality criteria that reflect
achieving the maximum feasible progress.  At the end of the first phase,
EPA would expect the water body to be meeting the first interim
designated use and water quality criteria.  

At the beginning of the second phase, the next (more stringent) interim
designated use and water quality criteria would go into effect as the
applicable WQS that the State would use to direct the next set of
control actions.  At the conclusion of the second phase, the next (more
stringent) interim designated use and water quality criteria would
become the applicable WQS.  This process would repeat with each
subsequent phase.  Permit limits written during the restoration phases
would include effluent limits as stringent as necessary to meet the
applicable interim designated uses and numeric water quality criteria. 
In constructing each restoration phase (i.e. duration and interim
designated use and numeric water quality criteria), EPA will require the
maximum feasible progress.  This means that necessary control actions
that would improve water quality and can be implemented within the first
phase must be reflected in the interim targets for the first restoration
phase.  This would include all technology-based requirements for point
sources, and cost-effective and reasonable BMPs for nonpoint sources. 
For treatment upgrades to point sources, EPA expects careful scrutiny of
technology that has been successfully implemented in comparable
situations and presumes that this is feasible  EPA further expects
careful scrutiny of all existing and new technology that will help
achieve the ultimate highest attainable use.

EPA recognizes that circumstances may change as controls are implemented
and that new information may indicate that the timeframes established in
the restoration WQS are too lengthy or possibly unrealistically short. 
If this is the case, the state has the discretion under CFR 131.10 to
conduct a new UAA and revise the interim targets in its restoration WQS
after a full public process and EPA approval.  However, there is a
significant burden on the state to demonstrate what changed to alter the
initial analysis and associated expectations for what was attainable for
that phase.  EPA would expect such a revision only if there was a
fundamental flaw in the original analysis or there was a significant new
information that demonstrated that a different schedule and/or set of
interim standards represents the maximum feasible progress towards the
final designated use and criteriamaterial change in circumstances that
was unforeseen.  

If at the end of a phase, the water body is not meeting interim targets,
then the restoration WQS would no longer be applicable.  In such a case,
the applicable WQS would be the ultimate highest attainable use and
associated criteria unless the State adopted and submitted for EPA
approval a revised WQS.  This would help ensure that there would be no
delay in implementing control measures.  Alternatively, EPA considered
an option of allowing the subsequent restoration phases to become
applicable on the schedule adopted in the restoration WQS and as
supported by the original UAA demonstration, even if the interim use and
criteria are not fully achieved on schedule.  This might have the
advantage of encouraging the adoption of ambitious interim goals in the
initial restoration standards, and would allow continued orderly
progress towards achievement of the final use and criterion even where
an interim step was not fully attained.  EPA solicits comment on this
alternative approach.   

To develop restoration WQS for numeric nutrient criteria, EPA would
expect that the State identify waters in need of restoration, produce an
inventory of point and nonpoint sources within the watershed, and
evaluate current ambient conditions and the necessary reductions to
achieve the numeric criteria.  The next part of the process would
involve determining the combinations of control strategies and
management practices available, how likely they are to produce results,
and the resources needed to implement them.  At this point, the State
would be in a good position to determine how much pollution reduction is
likely to be attainable under what timeframes.  The State could use this
information to establish the time periods for each restoration phase
consistent with the maximum feasible and attainable progress toward
meeting the numeric criteria, establish interim restoration designated
uses and water quality criteria, and make the necessary demonstration
that it is infeasible to attain the long-term designated use during the
time periods established and that the interim phases reflect the highest
attainable uses and associated criteria.

For excess nutrient pollution, the contributors to nutrient pollution
could include publicly-owned treatment works (POTWs), industrial
dischargers, urban and agricultural runoff, atmospheric deposition, and
septic systems.  Restoration WQS might reflect in an early phase, for
example, all feasible short-term POTW treatment upgrades and a schedule
to select, fund, and implement longer term nutrient reduction
technologies, while aggressively pursuing reductions in nonpoint source
runoff.    This might include specific plans and a schedule to develop
and implement innovative alternative approaches, such as trading
programs, where appropriate. 

In Florida, many of the steps described above occur in the context of
Basin Management Action Plans (BMAPs).  FDEP describes BMAPs as:

…the “blueprint” for restoring impaired waters by reducing
pollutant loadings to meet the allowable loadings established in a Total
Maximum Daily Load (TMDL). It represents a comprehensive set of
strategies--permit limits on wastewater facilities, urban and
agricultural best management practices, conservation programs, financial
assistance and revenue generating activities, etc.--designed to
implement the pollutant reductions established by the TMDL. These
broad-based plans are developed with local stakeholders--they rely on
local input and local commitment--and they are adopted by Secretarial
Order to be enforceable.
(http://www.dep.state.fl.us/Water/watersheds/bmap.htm) 

Florida has adopted BMAPs for the Hillsborough River Basin, Lower St.
John’s River, Log Branch, Orange Creek, and Upper Ocklawaha, and has
plans for others to follow.   To the extent necessary, FDEP could
potentially use aspects of the BMAP process and plans such as these to
help form the basis for restoration WQS. 

In summary, the WQS program is intended to protect and improve water
quality and WQS are meant to guide actions to address the effects of
pollution on the Nation’s waters.  The reality is that as more
assessments are being done and TMDLs are being contemplated, and as new
criteria are developed and considered, EPA and states face questions
about what pollution control measures will meet the WQS, how long it
might take, and whether it is feasible to attain the WQS established to
meet the goals of the Act.  These questions are often difficult to
answer because of lack of data, lack of knowledge, and lack of
experience in attempting restoration of waters.  Stakeholders and
co-regulators alike have expressed a desire for ways to pursue
progressive water quality improvement and evaluate those improvements to
gain the data, knowledge, and experience necessary to ultimately
determine the highest attainable use.  In response, EPA has been
investigating the best ways to use UAAs and related tools to make
progress in identifying and achieving the most appropriate designated
use.

EPA requests comments on the usefulness of the “restoration WQS”
proposal for Florida.  EPA requests comment on how restoration WQS will
operate in conjunction with listing impaired waters, and establishing
NPDES permit limitations, and nonpoint source control strategies, as
well as how these requirements should be reflected in regulatory
language.  EPA also requests comment on the proposed 20 year limit on
the schedule to attain the final use and criteria.  EPA also requests
comments on how a restoration WQS process would be coordinated with the
TMDL program and whether the transparency and review procedures for the
two approaches, including the conditions under which a State or EPA
would be required to develop a TMDL, are comparable.  EPA also requests
comment on any unintended adverse consequences for any of its water
quality programs. Finally, EPA requests comment on potential definitions
of “maximum feasible progress.”

VII. Statutory and Executive Order Reviews 

A. Executive Order 12866:  Regulatory Planning and Review  

Under Executive Order (EO) 12866   SEQ CHAPTER \h \r 1 (58 FR 51735,
October 4, 1993), this action is a "significant regulatory action.” 
Accordingly, EPA submitted this action to the Office of Management and
Budget (OMB) for review under EO 12866 and any changes made in response
to OMB recommendations have been documented in the docket for this
action.

	This proposed rule does not establish any requirements directly
applicable to regulated entities or other sources of nutrient pollution.
 Moreover, existing narrative water quality criteria in State law
already require that nutrients not be present in waters in
concentrations that cause an imbalance in natural populations of flora
and fauna in lakes and flowing waters in Florida.

B. Paperwork Reduction Act

This action does not impose an information collection burden under the
provisions of the Paperwork Reduction Act, 44 U.S.C. 3501 et seq. 
Burden is defined at 5 CFR 1320.3(b).  It does not include any
information collection, reporting, or record-keeping requirements.	

C. Regulatory Flexibility Act 

	The Regulatory Flexibility Act (RFA) generally requires an agency to
prepare a regulatory flexibility analysis of any rule subject to notice
and comment rulemaking requirements under the Administrative Procedure
Act or any other statute unless the agency certifies that the rule will
not have significant economic impact on a substantial number of small
entities.  Small entities include small businesses, small organizations,
and small governmental jurisdictions.

	For purposes of assessing the impacts of this action on small entities,
small entity is defined as: (1) A small business as defined by the Small
Business Administration's (SBA) regulations at 13 CFR 121.201; (2) a
small governmental jurisdiction that is a government of a city, county,
town, school district or special district with a population of less than
50,000; and (3) a small organization that is any not-for-profit
enterprise that is independently owned and operated and is not dominant
in its field.

	Under the CWA WQS program, states must adopt WQS for their waters and
must submit those WQS to EPA for approval; if the Agency disapproves a
state standard and the state does not adopt appropriate revisions to
address EPA’s disapproval, EPA must promulgate standards consistent
with the statutory requirements.  EPA also has the authority to
promulgate WQS in any case where the Administrator determines that a new
or revised standard is necessary to meet the requirements of the Act. 
These state standards (or EPA-promulgated standards) are implemented
through various water quality control programs including the NPDES
program, which limits discharges to navigable waters except in
compliance with an NPDES permit.  The CWA requires that all NPDES
permits include any limits on discharges that are necessary to meet
applicable WQS.

	Thus, under the CWA, EPA’s promulgation of WQS establishes standards
that the State implements through the NPDES permit process.  The State
has discretion in developing discharge limits, as needed to meet the
standards.  This proposed rule, as explained earlier, does not itself
establish any requirements that are applicable to small entities.  As a
result of this action, the State of Florida will need to ensure that
permits it issues include any limitations on discharges necessary to
comply with the standards established in the final rule.  In doing so,
the State will have a number of choices associated with permit writing. 
While Florida’s implementation of the rule may ultimately result in
new or revised permit conditions for some dischargers, including small
entities, EPA’s action, by itself, does not impose any of these
requirements on small entities; that is, these requirements are not
self-implementing.  Thus, I certify that this rule will not have a
significant economic impact on a substantial number of small entities.  


	EPA has prepared an analysis of potential costs associated with meeting
these standards.  EPA’s analysis uses the criteria proposed by FDEP in
July 2009 as a baseline against which to estimate the incremental costs
of meeting the standards in this proposal.  The baseline costs of
meeting Florida’s proposed standards are estimated to be $102 to $130
million per year.  The incremental costs, over and above these baseline
costs, of meeting the standards in this NPRM are estimated to be $4.7 to
$10.1 million per year.  This analysis assumes that most of these costs
would fall on non-point sources and the categories of point sources that
would be primarily affected are municipal wastewater treatment plants
and industrial and general dischargers.  EPA estimates the incremental
costs for these two categories of dischargers, including small entities,
at about $1 million per year.  

D. Unfunded Mandates Reform Act

	Title II of the Unfunded Mandates Reform Act of 1995 (UMRA), Public Law
104-4, establishes requirements for Federal agencies to assess the
effects of their regulatory actions on state, local, and tribal
governments and the private sector.  Under section 202 of the UMRA, EPA
generally must prepare a written statement, including a cost-benefit
analysis, for proposed and final rules with ``Federal mandates'' that
may result in expenditures to state, local, and Tribal governments, in
the aggregate, or to the private sector, of $100 million or more in any
one year.  Before promulgating an EPA rule for which a written statement
is needed, section 205 of the UMRA generally requires EPA to identify
and consider a reasonable number of regulatory alternatives and adopt
the least costly, most cost-effective or least burdensome alternative
that achieves the objectives of the rule.  The provisions of section 205
do not apply when they are inconsistent with applicable law.  Moreover,
section 205 allows EPA to adopt an alternative other than the least
costly, most cost-effective or least burdensome alternative if the
Administrator publishes with the final rule an explanation of why that
alternative was not adopted.  Before EPA establishes any regulatory
requirements that may significantly or uniquely affect small
governments, including tribal governments, it must have developed under
section 203 of the UMRA a small government agency plan.  The plan must
provide for notifying potentially affected small governments, enabling
officials of affected small governments to have meaningful and timely
input in the development of EPA regulatory proposals with significant
Federal intergovernmental mandates, and informing, educating, and
advising small governments on compliance with the regulatory
requirements.

	This proposed rule contains no Federal mandates (under the regulatory
provisions of Title II of the UMRA) for state, local, or tribal
governments or the private sector.  The State may use these resulting
water quality criteria in implementing its water quality control
programs.  This proposed rule does not regulate or affect any entity
and, therefore, is not subject to the requirements of sections 202 and
205 of UMRA.

	EPA determined that this proposed rule contains no regulatory
requirements that might significantly or uniquely affect small
governments.  Moreover, WQS, including those proposed here, apply
broadly to dischargers and are not uniquely applicable to small
governments.  Thus, this proposed rule is not subject to the
requirements of section 203 of UMRA.

E. Executive Order 13132 (Federalism)

This action does not have federalism implications.  It will not have
substantial direct effects on the states, on the relationship between
the national government and the states, or on the distribution of power
and responsibilities among the various levels of government, as
specified in Executive Order 13132.  EPA’s authority and
responsibility to promulgate Federal WQS when state standards do not
meet the requirements of the CWA is well established and has been used
on various occasions in the past.  The proposed rule would not
substantially affect the relationship between EPA and the states and
territories, or the distribution of power or responsibilities between
EPA and the various levels of government.  The proposed rule would not
alter Florida’s considerable discretion in implementing these WQS. 
Further, this proposed rule would not preclude Florida from adopting WQS
that meet the requirements of the CWA, either before or after
promulgation of the final rule, thus eliminating the need for Federal
standards.  Thus, Executive Order 13132 does not apply to this proposed
rule. 

Although section 6 of Executive Order 13132 does not apply to this
action, EPA had extensive communication with the State of Florida to
discuss EPA’s concerns with the State’s nutrient water quality
criteria and the Federal rulemaking process.  In the spirit of Executive
Order 13132, and consistent with EPA policy to promote communications
between EPA and state and local governments, EPA specifically solicits
comment on this proposed rule from State and local officials.

F. Executive Order 13175 (Consultation and Coordination with Indian
Tribal Governments)

Subject to the Executive Order 13175 (65 FR 67249, November 9, 2000) EPA
may not issue a regulation that has tribal implications, that imposes
substantial direct compliance costs, and that is not required by
statute, unless the Federal government provides the funds necessary to
pay the direct compliance costs incurred by tribal governments, or EPA
consults with tribal officials early in the process of developing the
proposed regulation and develops a tribal summary impact statement.  EPA
has concluded that this action may have tribal implications.  However,
the rule will neither impose substantial direct compliance costs on
tribal governments, nor preempt Tribal law. 

In the State of Florida, there are two Indian tribes, the Seminole Tribe
of Florida and the Miccosukee Tribe of Indians of Florida, with lakes
and flowing waters.  Both tribes have been approved for treatment in the
same manner as a state (TAS) status for CWA sections 303 and 401 and
have federally-approved WQS in their respective jurisdictions.  These
tribes are not subject to this proposed rule.  However, this rule may
impact the tribes because the numeric nutrient criteria for Florida will
apply to waters adjacent to the tribal waters.  

EPA has contacted the tribes to inform them of the potential future
impact this proposal could have on tribal waters.  A meeting with tribal
officials has been requested to discuss the draft proposed rule and
potential impacts on the tribes.  EPA specifically solicits additional
comment on this proposed rule from tribal officials. 

G. Executive Order 13045 (Protection of Children From Environmental
Health and Safety Risks)

This action is not subject to EO 13045 (62 FR 19885, April 23, 1997)
because it is not economically significant as defined in EO 12866, and
because the Agency does not believe the environmental health or safety
risks addressed by this action present a disproportionate risk to
children.

H. Executive Order 13211 (Actions That Significantly Affect Energy
Supply, Distribution, or Use)

This rule is not a “significant energy action” as defined in
Executive Order 13211, “Actions Concerning Regulations That
Significantly Affect Energy Supply,

Distribution, or Use” (66 FR 28355 (May 22, 2001)), because it is not
likely to have a significant adverse effect on the supply, distribution,
or use of energy.  

I. National Technology Transfer Advancement Act of 1995

Section 12(d) of the National Technology Transfer and Advancement Act of
1995 (“NTTAA”), Public Law 104–113, section 12(d) (15 U.S.C. 272
note) directs EPA to use voluntary consensus standards in its regulatory
activities unless to do so would be inconsistent with applicable law or
otherwise impractical.  Voluntary consensus standards are technical
standards (e.g., materials specifications, test methods, sampling
procedures, and business practices) that are developed or adopted by
voluntary consensus standards bodies.  The NTTAA directs EPA to provide
Congress, through OMB, explanations when the Agency decides not to use
available and applicable voluntary consensus standards.

This proposed rulemaking does not involve technical standards. 
Therefore, EPA is not considering the use of any voluntary consensus
standards.

J. Executive Order 12898 (Federal Actions To Address Environmental
Justice in Minority Populations and Low-Income Populations)	

	Executive Order (EO) 12898 (  HYPERLINK
"http://www.epa.gov/fedrgstr/eo/eo12898.htm"  59 FR 7629  (Feb. 16,
1994)) establishes Federal executive policy on environmental justice. 
Its main provision directs Federal agencies, to the greatest extent
practicable and permitted by law, to make environmental justice part of
their mission by identifying and addressing, as appropriate,
disproportionately high and adverse human health or environmental
effects of their programs, policies, and activities on minority
populations and low-income populations in the United States.

EPA has determined that this proposed rule does not have
disproportionately high and adverse human health or environmental
effects on minority or low-income populations because it would afford a
greater level of protection to both human health and the environment if
these numeric nutrient criteria are promulgated for Class I and Class
III waters in the State of Florida. 

List of Subjects in 40 CFR Part 131

Environmental protection, water quality standards, nutrients, Florida.

Dated:  

Lisa P. Jackson,

Administrator

For the reasons set out in the preamble, EPA proposes to amend 40 CFR
part 131 as follows:

PART 131 – WATER QUALITY STANDARDS 

1.  The authority citation for part 131 continues to read as follows:

	

	Authority:  33 U.S.C. 1251 et seq.

Subpart D-[Amended]

2.  Section 131.43 is added as follows:

§ 131.43 Florida.

(a) Scope.  This section promulgates numeric nutrient criteria for
lakes, streams, springs, canals, estuaries, and coastal waters in the
State of Florida.  This section also contains provisions for
site-specific criteria.

(b) Definitions. 

(1) Canal means a trench, the bottom of which is normally covered by
water with the upper edges of its two sides normally above water,
excluding all secondary and tertiary canals, classified as Class IV
waters, wholly within Florida’s agricultural areas.  

(2) Clear stream means a free-flowing water whose color is less than 40
platinum cobalt units (PCU). 

(3) Lake means a freshwater water body that is not a stream or other
watercourse with some open contiguous water free from emergent
vegetation.

(4) Lakes and flowing waters means inland surface waters that have been
classified as Class I (Potable Water Supplies) or Class III (Recreation,
Propagation and Maintenance of a Healthy, Well-Balanced Population of
Fish and Wildlife) water bodies pursuant to Rule 62-302.400, F.A.C.,
excluding wetlands, and are predominantly fresh waters.  

(5) Nutrient watershed region means an area of the State, corresponding
to coastal/estuarine drainage basin and differing geographical
conditions affecting nutrient levels, as delineated in the Technical
Support Document for EPA’s Proposed Rule for Numeric Nutrient Criteria
for Florida’s Inland Surface Fresh Waters.

(6) Predominantly fresh waters means surface waters in which the
chloride concentration at the surface is less than 1,500 milligrams per
liter. 

(7) Spring means the point where underground water emerges onto the
Earth’s surface, including its spring run. 

(8) Spring run means a free-flowing water that originates from a spring
or spring group whose primary (>50%) source of water is from a spring or
spring group.  

(9) State shall mean the State of Florida, whose transactions with the
U.S. EPA in matters related to this regulation are administered by the
Secretary, or officials delegated such responsibility, of the Florida
Department of Environmental Protection (FDEP), or successor agencies.

(10) Stream means a free-flowing, predominantly fresh surface water in a
defined channel, and includes rivers, creeks, branches, canals (outside
south Florida), freshwater sloughs, and other similar water bodies.  

(11) Surface water means water upon the surface of the earth, whether
contained in bounds created naturally or artificially or diffused. 
Water from natural springs shall be classified as surface water when it
exits from the spring onto the Earth’s surface.  

 

(c) Criteria for Florida waters.

g/L) a	Baseline Criteria b	Modified Criteria

 (within these bounds) c



TP (mg/L) a	TN (mg/L) a	TP (mg/L) a	TN (mg/L) a

Colored Lakes

> 40 PCU	20 	0.050	1.23	0.050-0.157	1.23-2.25

Clear Lakes, Alkaline

≤ 40 PCU d and > 50 mg/L CaCO3 e	20	0.030	1.00	0.030-0.087	1.00-1.81

Clear Lakes, Acidic

≤ 40 PCU d and ≤ 50 mg/L CaCO3 e	6	0.010	0.500	0.010-0.030
0.500-0.900

a Concentration values are based on annual geometric mean not to be
surpassed more than once in a three-year period.  In addition, the
long-term average of annual geometric mean values shall not surpass the
listed concentration values.  (Duration = annual; Frequency = not to be
surpassed more than once in a three-year period or as a long-term
average).

b Baseline criteria apply unless data are readily available to calculate
and apply lake-specific, modified criteria as described below in
footnote c and the Florida Department of Environmental Protection issues
a determination that a lake-specific modified criterion is the
applicable criterion for an individual lake.  Any such determination
must be made consistent with the provisions in footnote c below.  Such
determination must also be documented in an easily accessible and
publicly available location, such as an official State Web site.

c  If chlorophyll a is below the criterion in column B and there are
representative data to calculate ambient-based, lake-specific, modified
TP and TN criteria, then FDEP may calculate such criteria within these
bounds from ambient measurements to determine lake-specific, modified
criteria pursuant to CWA section 303(c).  Modified TN and TP criteria
must be based on at least three years of ambient monitoring data with
(a) at least four measurements per year and (b) at least one measurement
between May and September and one measurement between October and April
each year.  These same data requirements apply to chlorophyll a when
determining whether the chlorophyll a criterion is met for purposes of
developing modified TN and TP criteria.  If the calculated TN and/or TP
value is below the lower value, then the lower value is the
lake-specific, modified criterion. If the calculated TN and TP value is
above the upper value, then the upper value is the lake-specific,
modified criterion.  Modified TP and TN criteria may not exceed criteria
applicable to streams to which a lake discharges.  If chlorophyll a is
below the criterion in column B and representative data to calculate
modified TN and TP criteria are not available, then the baseline TN and
TP criteria apply.  Once established, modified criteria are in place as
the applicable WQS for all CWA purposes.  

d Platinum Cobalt Units (PCU) assessed as true color free from
turbidity.  Long-term average color based on a rolling average of up to
seven years using all available lake color data.

e If alkalinity data are unavailable, a specific conductance of 250
micromhos/cm may be substituted.

f Chlorophyll a is defined as corrected chlorophyll, or the
concentration of chlorophyll a remaining after the chlorophyll
degradation product, phaeophytin a, has been subtracted from the
uncorrected chlorophyll a measurement.

(2) Criteria for streams.  

(i)  The applicable instream protection value (IPV) criterion for total
nitrogen (TN) and total phosphorus (TP) for streams within each
respective nutrient watershed region is shown in the following table:

Nutrient  Watershed Region	Instream Protection Value Criteria

	TN (mg/L) a	TP (mg/L) a

Panhandle b

	0.824	0.043

Bone Valley c

	1.798	0.739

Peninsula d

	1.205	0.107

North Central e

	1.479	0.359

a Concentration values are based on annual geometric mean not to be
surpassed more than once in a three-year period.  In addition, the
long-term average of annual geometric mean values shall not surpass the
listed concentration values.  (Duration = annual; Frequency = not to be
exceeded more than once in a three-year period or as a long-term
average).

b Panhandle region includes the following watersheds: Perdido Bay
Watershed, Pensacola Bay Watershed, Choctawhatchee Bay Watershed, St.
Andrew Bay Watershed, Apalachicola Bay Watershed, Apalachee Bay
Watershed, and Econfina/Steinhatchee Coastal Drainage Area.

c Bone Valley region includes the following watersheds: Tampa Bay
Watershed, Sarasota Bay Watershed, and Charlotte Harbor Watershed.

d Peninsula region includes the following watersheds: Waccasassa Coastal
Drainage Area, Withlacoochee Coastal Drainage Area,
Crystal/Pithlachascotee Coastal Drainage Area, Indian River Watershed,
Caloosahatchee River Watershed, St. Lucie Watershed, Kissimmee River
Watershed, St. John’s River Watershed, Daytona/St. Augustine Coastal
Drainage Area, Nassau Coastal Drainage Area, and St. Mary’s River
Watershed.

e North Central region includes the Suwannee River Watershed.

Criteria for protection of downstream lakes.  

(A) The applicable total phosphorus criterion-magnitude for a stream
that flows into downstream lakes is the more stringent of the value from
the preceding table in (c)(2)(i) or a downstream lake protection value
derived from the following equation to protect the downstream lake: 

 

where

[TP]S is the total phosphorus (TP) downstream lake protection value,
mg/L

[TP]L is applicable TP lake criterion, mg/L

cf is the fraction of inflow due to all streamflow, 0 ( cf ( 1

w is lake’s hydraulic retention time (water volume divided by
annual flow rate)

  expresses the net phosphorus loss from the water column (e.g., via
settling of sediment-sorbed phosphorus) as a function of the lake’s
retention time.

w, respectively, are 0.5 and 0.2.  The State may substitute
site-specific values for these preset values where the State determines
that they are appropriate and documents the site-specific values in an
easily accessible and publicly available location, such as an official
State Web site. 

(iii) Criteria for protection of downstream estuarine waters. 

 ) where:

 ,						

and where the terms are defined as follows for a specific or ( ith )
stream reach:

 		maximum flow-averaged nutrient concentration for a specific (the ith
) stream reach consistent with downstream use protection (i.e., the DPV)

 		fraction of all loading to the estuary that comes from the stream
network resolved by SPARROW 

 	protective loading rate for the estuary, from all sources 

 	combined average freshwater discharged into the estuary from the
portion of the watershed resolved by the SPARROW stream network 

 		fraction of the flux at the downstream node of the specific ( ith)
reach that is transported through the stream network and ultimately
delivered to estuarine eceiving waters (i.e. Fraction Delivered).  

DPVs may not exceed other criteria established for designated use
protection in this section, nor result in an exceedance of other
criteria for other water quality parameters established pursuant to Rule
62-302, F.A.C. 

 except that Li is determined as a series of values for each reach in
the upstream drainage area such that the sum of reach-specific
incremental loading rates equals the target loading rate to the
downstream water protective of downstream uses, taking into account that
downstream reaches must reflect loads established for upstream reaches. 
Alternative DPVs may factor in additional nutrient attenuation provided
by already existing landscape modifications or treatment systems, such
as constructed wetlands or stormwater treatment areas.  For alternative
DPVs to become effective for Clean Water Act purposes, the State must
provide public notice and opportunity for comment.

(C)  To use an alternative technical approach of comparable scientific
rigor to quantitatively determine the protective load to the estuary and
associated protective stream concentrations, the State must go through
the process for a Federal site-specific alternative criterion pursuant
to paragraph (e) of this section.

(3) Criteria for springs, spring runs, and clear streams.  The
applicable nitrate-nitrite criterion is 0.35 mg/L as an annual geometric
mean not to be surpassed more than once in a three year period, nor
surpassed as a long-term average of annual geometric mean values.  In
addition to this nitrate-nitrite criterion, criteria identified in
paragraph (c)(2) of this section are applicable to clear streams.  

(4) Criteria for south Florida canals.  The applicable criterion for
chlorophyll a, total nitrogen (TN), and total phosphorus (TP) for canals
within each respective canal geographic classification area is shown on
the following table:

	Chlorophyll a

(µg/L) a	Total Phosphorus (TP)

(mg/L) a, b	Total Nitrogen (TN)

(mg/L) a

Canals	4.0 	0.042 	1.6 

a Concentration values are based on annual geometric mean not to be
surpassed more than once in a three-year period.  In addition, the
long-term average of annual geometric mean values shall not surpass the
listed concentration values.  (Duration = annual; Frequency = not to be
surpassed more than once in a three-year period or as a long-term
average).

b Applies to all canals within the Florida Department of Environmental
Protection’s South Florida bioregion, with the exception of canals
within the Everglades Protection Area (EvPA) where the TP criterion of
0.010 mg/L currently applies.

(5) Criteria for estuaries. [Reserved]

(6) Criteria for coastal waters. [Reserved]

(d) Applicability. 

(1) The criteria in paragraphs (c)(1) through (7) of this section apply
to surface waters of the State of Florida designated as Class I (Potable
Water Supplies) or Class III (Recreation, Propagation and Maintenance of
a Healthy, Well-Balanced Population of Fish and Wildlife) water bodies
pursuant to Rule 62-302.400, F.A.C., excluding wetlands, and apply
concurrently with other applicable water quality criteria, except when 

(i) State regulations contain criteria which are more stringent for a
particular parameter and use,

(ii) The Regional Administrator determines that site-specific
alternative criteria apply pursuant to the procedures in paragraph (e)
of this section, 

(iii) The State adopts and EPA approves a water quality standards
variance to the Class I or Class III designated use pursuant to §
131.13 that meets the applicable provisions of State law and the
applicable Federal regulations at § 131.10, or 

(iv) The State adopts and EPA approves restoration standards pursuant to
paragraph (g) of this rule.

(2) The criteria established in this section are subject to the
State’s general rules of applicability in the same way and to the same
extent as are the other federally-adopted and State-adopted numeric
criteria when applied to the same use classifications.  

(i) For all waters with mixing zone regulations or implementation
procedures, the criteria apply at the appropriate locations within or at
the boundary of the mixing zones; otherwise the criteria apply
throughout the water body including at the point of discharge into the
water body.  

(ii) The State shall use an appropriate design flow condition, where
necessary, for purposes of permit limit derivation or load and wasteload
allocations that is consistent with the criteria duration and frequency
established in this section (e.g., average annual flow for a criterion
magnitude expressed as an average annual geometric mean value).  

(iii) The criteria established in this section apply for purposes of
determining the list of impaired waters pursuant to section 303(d) of
the Clean Water Act, subject to the procedures adopted pursuant to Rule
62-303, F.A.C., where such procedures are consistent with the level of
protection provided by the criteria established in this section.

(e) Site-specific alternative criteria.

(1) Upon request from the State, the Regional Administrator may
determine that site-specific alternative criteria shall apply to
specific surface waters in lieu of the criteria established in paragraph
(c). Any such determination shall be made consistent with §131.11.

(2) To receive consideration from the Regional Administrator for a
determination of site-specific alternative criteria, the State must
submit a request that includes proposed alternative numeric criteria and
supporting rationale suitable to meet the needs for a technical support
document pursuant to paragraph (e)(3) of this section.

(3) For any determination made under paragraph (e)(1) of this section,
the Regional Administrator shall, prior to making such a determination,
provide for public notice and comment on a proposed determination.  For
any such proposed determination, the Regional Administrator shall
prepare and make available to the public a technical support document
addressing the specific surface waters affected and the justification
for each proposed determination. This document shall be made available
to the public no later than the date of public notice issuance.

(4) The Regional Administrator shall maintain and make available to the
public an updated list of determinations made pursuant to paragraph
(e)(1) of this section as well as the technical support documents for
each determination.

(5) Nothing in this paragraph (e) shall limit the Administrator's
authority to modify the criteria in paragraph (c) of this section
through rulemaking.

(f) Effective date. All criteria will be in effect [date 60 days after
publication of final rule].

Restoration Water Quality Standards (WQS). The State may, at its
discretion, adopt restoration WQS to allow attainment of a designated
use over phased time periods where the designated use is not currently
attainable as a result of nutrient pollution but is attainable in the
future.  In establishing restoration WQS, the State must:

(1) Demonstrate that the designated use is not attainable during the
time periods established for the restoration phases based on one of the
factors identified in §131.10(g)(1) through (6);

(2) Specify the designated use to be attained at the termination of the
restoration period, as well as the criteria necessary to protect such
use, provided that the final designated use and corresponding criteria
shall include, at a minimum, uses and criteria that are consistent with
CWA section 101(a)(2) ;  

(3) Establish interim restoration designated uses and water quality
criteria, that apply during each phase that will result in  maximum
feasible  progress toward the highest attainable designated use and the
use identified in paragraph (g)(2) of this section.  Such interim uses
and criteria may not provide for further degradation of a water body and
may be revised prior to the end of each phase in accordance with
§131.10 and 131.20and submitted to EPA for approval;

(4) Establish the time periods for each restoration phase that will
result in maximum feasible  progress toward the highest attainable use
and the designated use identified in paragraph (g)(2) of this section,
except that the sum of such time periods shall not exceed twenty years
from the initial date of establishment of the restoration WQS under this
section;  (5) Specify the spatial extent of applicability for all
affected waters; 

(6) Meet the requirements of §§131.10 and 131.20; and   

(7) Include, in its State water quality standards, a specific provision
that if the interim restoration designated uses and criteria established
under paragraph (g)(3) of this section are not met during any phased
time period established under paragraph (4) of this section, the
restoration WQS will no longer be applicable and the designated use and
criteria identified in paragraph (g)(2) of this section will become
applicable immediately.

(8) Provide that waters for which a restoration water quality standard
is adopted will be recognized as impaired for the purposes of listing
impaired waters under section 303(d) of the CWA until the use designated
identified in paragraph (2) of this section is attained. 

 Florida Department of Environmental Protection. 2008. Integrated Water
Quality Assessment for Florida: 2008 305(b) Report and 303(d) List
Update, p.67.

 http://www.census.gov/population/projections/SummaryTabA1.pdf

 To be used by living organisms, nitrogen gas must be fixed into its
reactive forms; for plants, either nitrate or ammonia. 

 Eutrophication is defined as an increase in organic carbon to an
aquatic ecosystem caused by primary productivity stimulated by excess
nutrients - typically compounds containing nitrogen or phosphorus. 
Eutrophication can adversely affect aquatic life, recreation, and human
health uses of waters.  

 Villanueva, C.M. et al., 2006. Bladder Cancer and Exposure to Water
Disinfection By-Products through Ingestion, Bathing, Showering, and
Swimming in Pools. American Journal of Epidemiology, 165(2):148-156.

 U.S. EPA. 2009. What Is in Our Drinking Water. United States
Environmental Protection Agency, Office of Research and Development. <  
HYPERLINK
"http://www.epa.gov/extrmurl/research/process/drinkingwater.html" 
http://www.epa.gov/extrmurl/research/process/drinkingwater.html >.
Accessed December 2009.

 National Research Council, 2000. Clean Coastal Waters: Understanding
and Reducing the Effects of Nutrient Pollution. Report prepared by the
Ocean Study Board and Water Science and Technology Board, Commission on
Geosciences, Environment and Resources, National Resource Council.
National Academy Press, Washington, D.C.; Howarth, R.W., A. Sharpley,
and D. Walker. 2002. Sources of nutrient pollution to coastal waters in
the United States: Implications for achieving coastal water quality
goals. Estuaries. 25(4b):656-676; Smith, V.H. 2003. Eutrophication of
freshwater and coastal marine ecosystems. Environ. Sci.and Poll. Res.
10(2):126-139; Dodds, W.K., W.W. Bouska, J.L. Eitzmann, T.J. Pilger,
K.L. Pitts, A.J. Riley, J.T. Schloesser, and D.J. Thornbrugh. 2009.
Eutrophication of U.S. freshwaters: Analysis of potential economic
damages. Environ. Sci. Tech.. 43(1):12-19.

 Hauxwell, J. C. Jacoby, T. Frazer, and J. Stevely. 2001. Nutrients and
Florida’s Coastal Waters. Florida Sea Grant.

 NOAA. 2009. Harmful Algal Blooms: Current Programs Overview. National
Oceanic and Atmospheric Administration.
<http://www.cop.noaa.gov/stressors/extremeevents/hab/welcome.html>.
Accessed December 2009.

 NOAA. 2009. Harmful Algal Blooms: Current Programs Overview. National
Oceanic and Atmospheric Administration. <
http://www.cop.noaa.gov/stressors/extremeevents/hab/welcome.html>.
Accessed December 2009.

 WHOI. 2008. HAB Impacts on Wildlife. Woods Hole Oceanographic
Institution. <http://www.whoi.edu/redtide/page.do?pid=9682>. Accessed
December 2009.

 WHOI. 2008. Marine Mammals. Woods Hole Oceanographic Institution.
<http://www.whoi.edu/redtide/page.do?pid=14215>. Accessed December 2009.

 WHOI. 2008. HAB Impacts on Wildlife. Woods Hole Oceanographic
Institution. <http://www.whoi.edu/redtide/page.do?pid=9682>. Accessed
December 2009.

 WHOI. 2008. Marine Mammals. Woods Hole Oceanographic Institution.
<http://www.whoi.edu/redtide/page.do?pid=14215>. Accessed December 2009.

 WHOI. 2008. Marine Mammals. Woods Hole Oceanographic Institution.
<http://www.whoi.edu/redtide/page.do?pid=14215>. Accessed December 2009.

 WHOI. 2008. HAB Impacts on Wildlife. Woods Hole Oceanographic
Institution. <http://www.whoi.edu/redtide/page.do?pid=9682>. Accessed
December 2009.

 Falconer, I.R., A.R. Humpage. 2005. Health Risk Assessment of
Cyanobacterial (Blue-green Algal) Toxins in Drinking Water. Int. J.
Environ. Res. Public Health. 2(1): 43-50.

 NOAA. 2009. Harmful Algal Blooms: Current Programs Overview. National
Oceanic and Atmospheric Administration.
<http://www.cop.noaa.gov/stressors/extremeevents/hab/welcome.html>.
Accessed December 2009.

 USGS. 2009. Hypoxia. U.S. Geological Survey.
<http://toxics.usgs.gov/definitions/hypoxia.html>. Accessed December
2009.

 ESA. 2009. Hypoxia. Ecological Society of America.
<http://www.esa.org/education_diversity/pdfDocs/hypoxia.pdf>. Accessed
December 2009.

 USEPA. 2000. Ambient Aquatic Life Water Quality Criteria for Dissolved
Oxygen (Saltwater): Cape Cod to Cape Hattaras. Environmental Protection
Agency, Office of Water, Washington D.C. PA-822-R-00-012.

 Ecological Society of America. 2009. Hypoxia. Ecological Society of
America, Washington, D.C. <   HYPERLINK
"http://www.esa.org/education/edupdfs/hypoxia.pdf" 
http://www.esa.org/education/edupdfs/hypoxia.pdf > Accessed December
2009.

 USEPA. 2007. Nitrates and Nitrites. U.S. Environmental Protection
Agency. <http://www.epa.gov/teach/chem_summ/Nitrates_summary.pdf>.
Accessed December 2009.

 FDEP 2009. Chemical Data for 2004, 2005, 2006, 2007 and 2008. Florida
Department of Environmental Protection.<   HYPERLINK
"http://www.dep.state.fl.us/water/drinkingwater/chemdata.htm" 
http://www.dep.state.fl.us/water/drinkingwater/chemdata.htm >. Accessed
January 2010.

 Southern Regional Water Program.  2010. Drinking Water and Human Health
in Florida. Southern Regional Water Program, <   HYPERLINK
"http://srwqis.tamu.edu/florida/program-information/florida-target-theme
s/drinking-water-and-human-health.aspx" 
http://srwqis.tamu.edu/florida/program-information/florida-target-themes
/drinking-water-and-human-health.aspx >.  Accessed January 2010.

 USEPA. 2009. Drinking Water Contaminants. U.S. Environmental Protection
Agency. Accessed <http://www.epa.gov/safewater/hfacts.html>. December
2009.

 CFR. 2006. 40 CFR parts 9, 141, and 142: National Primary Drinking
Water Regulations: Stage 2 Disinfectants and Disinfection Byproducts
Rule. Code of Federal Regulations, Washington, DC.
<http://www.epa.gov/fedrgstr/EPA-WATER/2006/January/Day-04/w03.htm>.
Accessed December 2009.

 Carmichael, W.W. 2000. Assessment of Blue-Green Algal Toxins in Raw and
Finished Drinking Water. AWWA Research Foundation, Denver, CO.

 NOAA. 2009. Marine Biotoxins. National Oceanic and Atmospheric
Administration.
<http://www.nwfsc.noaa.gov/hab/habs_toxins/marine_biotoxins/index.html>.
Accessed December 2009.

 WHOI. 2008. Hearing on 'Harmful Algal Blooms: The Challenges on the
Nation’s Coastlines.' Woods Hole Oceanographic Institution.
<http://www.whoi.edu/page.do?pid=8916&tid=282&cid=46007>. Accessed
December 2009.

 Dodds, W.K., W.W. Bouska, J.L. Eitzmann, T.J. Pilger, K.L. Pitts, A.J.
Riley, J.T. Schloesser, and D.J. Thornbrugh. 2009. Eutrophication of
U.S. freshwaters: analysis of potential economic damages. Environ.l Sci.
Tech.y. 43(1):12–19.

 Florida Department of Environmental Protection. 2008. Integrated Water
Quality Assessment for Florida: 2008 305(b) Report and 303(d) List
Update.

 Florida Department of Environmental Protection. 2008. Integrated Water
Quality Assessment for Florida: 2008 305(b) Report and 303(d) List
Update.

 U.S. Census Bureau.  2009.  2008 Population Estimates Ranked by State. 
http://factfinder.census.gov

 Perry, W. B. 2008. Everglades restoration and water quality challenges
in south Florida. Ecotoxicology 17:569-578. 

 USGS. 2009. Florida Waters: A Water Resources Manual.
<http://sofia.usgs.gov/publications/reports/floridawaters/>. Accessed
June 9, 2009.

 Florida Department of Environmental Protection. 2008. Integrated Water
Quality Assessment for Florida: 2008 305(b) Report and 303(d) List
Update.

 U.S. EPA. 2000a.  Nutrient Criteria Technical Guidance Manual:  Lakes
and Reservoirs.  Office of Water, Washington, DC.  EPA-822-B-00-001.

 U.S. EPA. 2000b.  Nutrient Criteria Technical Guidance Manual:  Rivers
and Streams.  Office of Water, Washington, DC.  EPA-822-B-00-002.

 U.S. EPA. 2001.  Nutrient Criteria Technical Manual:  Estuarine and
Coastal Marine Waters.  Office of Water, Washington, DC.
EPA-822-B-01-003), and wetlands (U.S. EPA, 2007).

 FDEP. 2008. Integrated Water Quality Assessment for Florida: 2008
305(b) Report and 303(d) List Update. Florida Department of
Environmental Protection.

 Fernald, E.A. and E.D. Purdum.  1998.  Water Resources Atlas of
Florida.  Tallahassee:  Institute of Science and Public Affairs, Florida
State University.

 U.S. EPA. 1998. National Strategy for the Development of Regional
Nutrient Criteria. Office of Water, Washington, D.C. EPA 822-R-98-002;
Grubbs, G. 2001. U.S. EPA. (Memorandum to Directors of State Water
Programs, Directors of Great Water Body Programs, Directors of
Authorized Tribal Water Quality Standards Programs and State and
Interstate Water Pollution Control Administrators on Development and
Adoption of Nutrient Criteria into Water Quality Standards.  November
14, 2001); Grumbles, B.H. 2007. U.S. EPA. (Memorandum to Directors of
State Water Programs, Directors of Great Water Body Programs, Directors
of Authorized Tribal Water Quality Standards Programs and State and
Interstate Water Pollution Control Administrators on Nutrient Pollution
and Numeric Water Quality Standards.  May 25, 2007).

 U.S. EPA. 2000. Nutrient Criteria Technical Guidance Manual: Rivers and
Streams. Office of Water, Washington, DC. EPA-822-B-00-002.

 Shannon, E.E. and P.L. Brezonik.  1972.  Limnological characteristics
of north and central Florida lakes.  Limnol. Oceanogr.  17(1): 97-110.

 Trophic state describes the nutrient and algal state of an aquatic
system: oligotrophic (low nutrients and algal productivity), mesotrophic
(moderate nutrients and algal productivity), and eutrophic (high
nutrients and algal productivity).

 Carlson, R.E. 1977. A trophic state index for lakes. Limnol. Oceanogr..
22:361-369.

Carlson, R.E. 1977. A trophic state index for lakes. Limnol. Oceanogr..
22:361-369.

 Salas and Martino. 1991. A simplified phosphorus trophic state index
for warm water tropical lakes. Wat. Res. 25:341-350.

 Whitmore and Brenner. 2002. Paleologic characterization of
pre-disturbance water quality conditions in EPA defined Florida lake
regions. Univ. Florida Dept. Fisheries and Aquatic Sciences. 30 pp.

 Vighi and Chiaudani. 1985. A simple method to estimate lake phosphorus
concentrations resulting from natural background loadings. Wat.
Res.19:987-991.

 Canfield, D.E., Jr., M.J. Maceina, L.M. Hodgson, and K.A. Langeland.
1983. Limnological features of some northwestern Florida lakes.  J.
Freshw. Ecol. 2:67-79; Griffith, G. E., D. E. Canfield, Jr., C. A.
Horsburgh, J. M. Omernik, and S. H. Azevedo. 1997. Lake regions of
Florida. Map prepared by U. S. EPA, Corvallis, OR; available at  
HYPERLINK "http://www.epa.gov/wed/pages/ecoregions/fl_eco.htm" 
http://www.epa.gov/wed/pages/ecoregions/fl_eco.htm  (accessed
10/09/2009).

 More information on this issue is available on FDEP’s Web site at < 
HYPERLINK
"http://www.dep.state.fl.us/water/wqssp/nutrients/docs/dep_responses_100
909.pdf" 
http://www.dep.state.fl.us/water/wqssp/nutrients/docs/dep_responses_1009
09.pdf > and included in the “External Peer Review of EPA’s
‘Proposed Methods and Approaches for Developing Numeric Nutrient
Criteria for Florida’s Inland Waters’” and EPA’s TSD for
Florida’s Inland Waters located in the docket ID No.
EPA-HQ-OW-2009-0596.  

 FDEP document titled, “DEP’s Responses to EPA’s 9/16 Comment
Letter.” October 9, 2009.  Located in the docket ID
EPA-HQ-OW-2009-0596.

 USEPA. Guidance for 2004 Assessment, Listing and Reporting Requirements
Pursuant to Sections 303(d) and 305(b) of the Clean Water Act. < 
HYPERLINK "http://www.epa.gov/OWOW/tmdl/tmdl0103/" 
http://www.epa.gov/OWOW/tmdl/tmdl0103/ >  Accessed December 2009.

 Kenney (1998) as reported in Salas and Martino (1991).

 Jeppeson et al. 2005. Lake responses to reduced nutrient loading – an
analysis

of contemporary long-term data from 35 case studies. Freshwater Biology
50: 1747–1771.

 Griffith, G. E., D. E. Canfield, Jr., C. A. Horsburgh, J. M. Omernik,
and S. H. Azevedo. 1997.

Florida lake regions. U. S. EPA, Corvallis, OR.
http://www.epa.gov/wed/pages/ecoregions/fl_eco.htm

 U.S. EPA. 1998. National Strategy for the Development of Regional
Nutrient Criteria. Office of Water, Washington, D.C. EPA 822-R-98-002;
Grubbs, G. 2001. U.S. EPA. (Memorandum to Directors of State Water
Programs, Directors of Great Water Body Programs, Directors of
Authorized Tribal Water Quality Standards Programs and State and
Interstate Water Pollution Control Administrators on Development and
Adoption of Nutrient Criteria into Water Quality Standards.  November
14, 2001); Grumbles, B.H. 2007. U.S. EPA. (Memorandum to Directors of
State Water Programs, Directors of Great Water Body Programs, Directors
of Authorized Tribal Water Quality Standards Programs and State and
Interstate Water Pollution Control Administrators on Nutrient Pollution
and Numeric Water Quality Standards.  May 25, 2007).

 U.S. EPA. 2000. Nutrient Criteria Technical Guidance Manual: Rivers and
Streams. Office of Water, Washington, DC. EPA-822-B-00-002.

 U.S. EPA. 2000. Nutrient Criteria Technical Guidance Manual: Lakes and
Reservoirs. Office of Water, Washington, DC. EPA-822-B-00-001; U.S.EPA.
2000. Nutrient Criteria Technical Guidance Manual:  Rivers and Streams.
Office of Water, Washington, DC. EPA-822-B-00-002; U.S. EPA.2001.
Nutrient Criteria Technical Manual: Estuarine and Coastal Marine Waters.
Office of Water, Washington, DC. EPA-822-B-01-003.

 U.S. EPA. 2000. Nutrient Criteria Technical Guidance Manual: Rivers and
Streams. Office of Water. 4304. EPA-822-B-00-002.

 The SCI method was developed and calibrated by FDEP.  See “Fore et
al. 2007. Development and testing biomonitoring tools for
macroinvertebrates in Florida streams (Stream Condition Index and
BioRecon). Final report to Florida Department of Environmental
Protection” and the EPA TSD for Florida’s Inland Waters for more
information on the SCI.

 Appendix H in “Fore et al. 2007. Development and testing
biomonitoring tools for macroinvertebrates in Florida streams (Stream
Condition Index and BioRecon). Final report to Florida Department of
Environmental Protection”

 See the EPA TSD for Florida’s Inland Waters for more information on
the proportional odds regression model.

 FL IWR and STORET can be found at:
http://www.dep.state.fl.us/WATER/STORET/INDEX.HTM

 U.S. EPA. 2000. Nutrient Criteria Technical Guidance Manual: Rivers and
Streams. Office of Water. 4304. EPA-822-B-00-002;

 A quantitative, integrated measure of the degree of human landscape
disturbance within 100 meters on either side of a specified stream reach
and extending to 10 kilometers upstream of the same stream reach.

 FDEP document titled, “Responses to Earthjustice’s Comments on the
Department’s Reference Sites.” Draft October 2, 2009.  Located in
the docket ID EPA-HQ-OW-2009-0596.

 Vollenweider, R.A. 1975.  Input-output models with special reference to
the phosphorus loading concept in limnology.  Schweizerische Zeitschrift
fur Hydrologie. 37: 53-84; Vollenweider, R.A. 1976. Advances in
differing critical loading levels for phosphorus in lake eutrophication.
 Mem. Ist. Ital. Idrobid. 33:53:83.

 Fernald, E.A. and E.D. Purdum.  1998.  Water Resources Atlas of
Florida.  Tallahassee:  Institute of Science and Public Affairs, Florida
State University.

 Gao, X.  2006.  Nutrient and Unionized Ammonia TMDLs for Lake Jesup,
WBIDs 2981 and 2981A.  Prepared by Florida Department of Environmental
Protection, Division of Water Resource Management, Bureau of Watershed
Management, Tallahassee, FL.

 Steward, J.S. and E.F. Lowe.  In Press.  General empirical models for
estimating nutrient load limits for Florida’s estuaries and inland
waters.  Limnol. Oceanogr.  55: (in press).

 Kennedy, R. H., 1995. Application of the BATHTUB Model to Selected
Southeastern Reservoirs. Technical Report EL-95-14, U.S. Army Engineer
Waterways Experiment Station, Vicksburg, MS. 

Walker, W. W., 1985. Empirical Methods for Predicting Eutrophication in
Impoundments; Report 3, Phase II: Model Refinements. Technical Report
E-81-9, U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS. 

Walker, W. W., 1987. Empirical Methods for Predicting Eutrophication in
Impoundments; Report 4, Phase III: Applications Manual. Technical Report
E-81-9, U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS. 

 http://water.usgs.gov/nawqa/sparrow

 Hoos, A. B., and G. McMahon.  2009.  Spatial analysis of instream
nitrogen loads and factors controlling nitrogen delivery to stream in
the southeastern United Sates using spatially referenced regression on
watershed attributes (SPARROW) and regional classification frameworks. 
Hydrological Processes.  DOI: 10.1002/hyp.7323. 

 Hoos, A.B., S. Terziotti,, G. McMahon, K. Savvas, K. C. Tighe, and R.
Alkons-Wolinsky.  2008.  Data to support statistical modeling of
instream nutrient load based on watershed attributes, southeastern
United States, 2002: U.S. Geological Survey Open-File Report
2008–1163, 50 p.

 USGS SPARROW publications Web site:   HYPERLINK
"http://water.usgs.gov/nawqa/sparrow/intro/pubs.html" 
http://water.usgs.gov/nawqa/sparrow/intro/pubs.html 

 Bricker, S., B. Longstaff, W. Dennison, A. Jones, K. Boicourt, C. Wicks
and J. Woerner, 2007. Effects of nutrient enrichment in the Nation’s
estuaries: A decade of change. NOAA Coastal Ocean Program Decision
Analysis Series No. 26. National Centers for Coastal Ocean Science,
Silver Spring, MD 322 

 Hoos, A. B., and G. McMahon.  2009.  Spatial analysis of instream
nitrogen loads and factors controlling nitrogen delivery to stream in
the southeastern United Sates using spatially referenced regression on
watershed attributes (SPARROW) and regional classification frameworks. 
Hydrological Processes.  DOI: 10.1002/hyp.7323.

 Hoos, A.B., S. Terziotti,, G. McMahon, K. Savvas, K. C. Tighe, and R.
Alkons-Wolinsky.  2008.  Data to support statistical modeling of
instream nutrient load based on watershed attributes, southeastern
United States, 2002: U.S. Geological Survey Open-File Report
2008–1163, 50 p.

 Steward, J.S. and E.F. Lowe.  2010.  General empirical models for
estimating nutrient load limits for Florida’s estuaries and inland
waters.  Limnology and Oceanography 55(1):433-445.  

For further information on concerns raised by FDEP regarding the use of
SPARROW, refer to "Florida Department of Environmental Protection Review
of SPARROW:  How useful is it for the purposes of supporting water
quality standards development?," “Assessment of FDEP Panhandle Stream
proposed benchmark numeric nutrient criteria for downstream protection
of Apalachicola Bay,” and “Analysis of Proposed Freshwater Stream
Criteria’s Relationship to Protective Levels in the Lower St. Johns
River Based on the Lower St. Johns River Nutrient TMDL.” 

located in EPA’s docket ID No. EPA-HQ-OW-2009-0596.

 Hoos, A. B., and G. McMahon.  2009.  Spatial analysis of instream
nitrogen loads and factors controlling nitrogen delivery to stream in
the southeastern United Sates using spatially referenced regression on
watershed attributes (SPARROW) and regional classification frameworks. 
Hydrological Processes.  DOI: 10.1002/hyp.7323.

 Bohlke, J.K., R.C. Antweiler, J.W. Harvey, A.E. Laursen, L.K. Smith, R.
L. Smith, and M.A. Voytek. 2009. Multi-scale measurements and modeling
of Denitrification in streams with varying flow and nitrate
concentration in the upper Mississippi River basin, USA. Biogeochemistry
93: 117-141. DOI 10.1007/s10533-008-9282-8.

 Hoos, A.B., S. Terziotti,, G. McMahon, K. Savvas, K. C. Tighe, and R.
Alkons-Wolinsky.  2008.  Data to support statistical modeling of
instream nutrient load based on watershed attributes, southeastern
United States, 2002: U.S. Geological Survey Open-File Report
2008–1163, 50 p.

 Brown M.T., K. Chinners Reiss, M.J. Cohen, J.M. Evans, P.W. Inglett, K.
Sharma Inglett, K. Ramesh Reddy, T.K. Fraze, C.A. Jacoby, E.J. Phlips,
R.L. Knight, S.K. Notestein, R.G. Hamann, and K.A. McKee. 2008. Summary
and Synthesis of the Available Literature on the Effects of Nutrients on
Spring Organisms and Systems.     HYPERLINK
"http://www.dep.state.fl.us/springs/reports/files/UF_SpringsNutrients_Re
port.pdf" 
http://www.dep.state.fl.us/springs/reports/files/UF_SpringsNutrients_Rep
ort.pdf , University of Florida, Gainesville, Florida.

 Scott, T.M., G.H. Means, R.P. Meegan, R.C. Means, S.B. Upchurch, R.E.
Copeland, J. Jones, T. Roberts, and A. Willet. 2004. Springs of Florida.
Bulletin No, 66. Florida Geological Survey. Tallahassee, FL. 677 pp.

 Katz, B.G., H.D. Hornsby, J.F. Bohlke and M.F. Mokray. 1999. Sources
and chronology of nitrate contamination in spring water, Suwannee River
Basin, Florida. U. S. Geological Survey Water-Resources Investigations
Report 99-4252. Reston, VA.

 Brown M.T., K. Chinners Reiss, M.J. Cohen, J.M. Evans, P.W. Inglett, K.
Sharma Inglett, K. Ramesh Reddy, T.K. Fraze, C.A. Jacoby, E.J. Phlips,
R.L. Knight, S.K. Notestein, R.G. Hamann, and K.A. McKee. 2008. Summary
and Synthesis of the Available Literature on the Effects of Nutrients on
Spring Organisms and Systems.     HYPERLINK
"http://www.dep.state.fl.us/springs/reports/files/UF_SpringsNutrients_Re
port.pdf" 
http://www.dep.state.fl.us/springs/reports/files/UF_SpringsNutrients_Rep
ort.pdf , University of Florida, Gainesville, Florida.

 Ibid.

 Katz, B.G., H.D. Hornsby, J.F. Bohlke and M.F. Mokray. 1999. Sources
and chronology of nitrate contamination in spring water, Suwannee River
Basin, Florida. U. S. Geological Survey Water-Resources Investigations
Report 99-4252. Reston, VA.

 Doyle, R.D. and R.M. Smart. 1998. Competitive reduction of noxious
Lyngbya wollei mats by rooted aquatic plants. Aquatic Botany 61:17-32.

 Stevenson, R.J., A. Pinowska, A. Albertin, and J.O. Sickman. 2007.
Ecological condition of algae and nutrients in Florida springs: The
Synthesis Report. Prepared for the Florida Department of Environmental
Protection. Tallahassee, FL. 58 pp.

Bonn, M.A. and F.W. Bell. 2003. Economic Impact of Selected Florida
Springs on Surrounding Local Areas. Report prepared for the Florida
Department of Environmental Protection. Tallahassee, FL.

 Pinowska, A., R.J. Stevenson, J.O. Sickman, A. Albertin, and M.
Anderson. 2007. Integrated interpretation of survey for determining
nutrient thresholds for macroalgae in Florida Springs: Macroalgal
relationships to water, sediment and macroalgae nutrients, diatom
indicators and land use. Florida Department of Environmental Protection,
Tallahassee, FL.

 Stevenson,R.J., A. Pinowska, and Y.K. Wang. 2004. Ecological condition
of algae and nutrients in Florida springs. Florida Department of
Environmental Protection, Tallahassee, FL.              

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, J.M. Lloyd, T.M. Scott, S.B. Upchurch and R. Copeland. 1992.
Florida’s Groundwater Quality Monitoring Program – Background
Hydrochemistry. Florida Geological Survey Special Publication 34.
Tallahassee, FL.

 Katz, B.G., H.D. Hornsby, J.F. Bohlke and M.F. Mokray. 1999. Sources
and chronology of nitrate contamination in spring water, Suwannee River
Basin, Florida. U. S. Geological Survey Water-Resources Investigations
Report 99-4252. Reston, VA.

Brown M.T., K. Chinners Reiss, M.J. Cohen, J.M. Evans, P.W. Inglett, K.
Sharma Inglett, K. Ramesh Reddy, T.K. Fraze, C.A. Jacoby, E.J. Phlips,
R.L. Knight, S.K. Notestein, R.G. Hamann, and K.A. McKee. 2008. Summary
and Synthesis of the Available Literature on the Effects of Nutrients on
Spring Organisms and Systems.     HYPERLINK
"http://www.dep.state.fl.us/springs/reports/files/UF_SpringsNutrients_Re
port.pdf" 
http://www.dep.state.fl.us/springs/reports/files/UF_SpringsNutrients_Rep
ort.pdf , University of Florida, Gainesville, Florida.

 Scott, T.M., G.H. Means, R.P. Meegan, R.C. Means, S.B. Upchurch, R.E.
Copeland, J. Jones, T. Roberts, and A. Willet. 2004. Springs of Florida.
Bulletin No, 66. Florida Geological Survey. Tallahassee, FL. 677 pp.

 Brown M.T., K. Chinners Reiss, M.J. Cohen, J.M. Evans, P.W. Inglett, K.
Sharma Inglett, K. Ramesh Reddy, T.K. Fraze, C.A. Jacoby, E.J. Phlips,
R.L. Knight, S.K. Notestein, R.G. Hamann, and K.A. McKee. 2008. Summary
and Synthesis of the Available Literature on the Effects of Nutrients on
Spring Organisms and Systems.     HYPERLINK
"http://www.dep.state.fl.us/springs/reports/files/UF_SpringsNutrients_Re
port.pdf" 
http://www.dep.state.fl.us/springs/reports/files/UF_SpringsNutrients_Rep
ort.pdf , University of Florida, Gainesville, Florida.

 Brown M.T., K. Chinners Reiss, M.J. Cohen, J.M. Evans, P.W. Inglett, K.
Sharma Inglett, K. Ramesh Reddy, T.K. Fraze, C.A. Jacoby, E.J. Phlips,
R.L. Knight, S.K. Notestein, R.G. Hamann, and K.A. McKee. 2008. Summary
and Synthesis of the Available Literature on the Effects of Nutrients on
Spring Organisms and Systems.     HYPERLINK
"http://www.dep.state.fl.us/springs/reports/files/UF_SpringsNutrients_Re
port.pdf" 
http://www.dep.state.fl.us/springs/reports/files/UF_SpringsNutrients_Rep
ort.pdf , University of Florida, Gainesville, Florida.

 Stevenson, R.J., A. Pinowska, A. Albertin, and J.O. Sickman. 2007.
Ecological condition of algae and nutrients in Florida springs: The
Synthesis Report. Prepared for the Florida Department of Environmental
Protection. Tallahassee, FL. 58 pp.

Cowell, B. C. and C. J. Dawes. 2004. Growth and nitrate-nitrogen uptake
by the cyanobacterium Lyngbya wollei.  J. Aquatic Plant Management 42:
69-71.

 Gao, X.. 2008. Nutrient TMDLs for the Wekiva River (WBIDs 2956, 2956A,
and 2956C) and Rock Springs Run (WBID 2967). Florida Department of
Environmental Protection, Tallahassee, Florida.

 Mattson, R. A., E. F. Lowe, C. L. Lippincott, D. Jian, and L. Battoe.
2006. Wekiva River and Rock Springs Run Pollutant Load Reduction Goals.
St. Johns River Water Management District, Palatka, Florida.

 Gao, X.  2008.  Nutrient TMDLs for the Wekiva River (WBIDs 2956, 2956A,
2956C) and Rock Springs Run (WBID 2967).  Florida Department of
Environmental Protection, Tallahassee, Florida.

 Stevenson, R.J., A. Pinowska, A. Albertin, and J.O. Sickman. 2007.
Ecological condition of algae and nutrients in Florida springs: The
Synthesis Report. Prepared for the Florida Department of Environmental
Protection. Tallahassee, FL. 58 pp.

 Proposed Total Maximum Daily Load (TMDL) for Dissolved Oxygen and
Nutrient in the Everglades. Prepared by U.S. EPA Region 4. September
2007.

 State Soil Geographic (STATSGO) database provided by the U.S.
Department of Agriculture, Natural Resources Conservation Service
(NRCS).

 Proposed Total Maximum Daily Load (TMDL) for Dissolved Oxygen and
Nutrient in the Everglades. Prepared by U.S. EPA Region 4. September
2007.

 Clean Water Act section 101(a)(2) states that it is a national goal for
water quality, wherever attainable,  to provide for the protection and
propagation of fish, shellfish, and wildlife and provide for recreation
in and on the water

 A variance is a temporary modification to the designated use and
associated water quality criteria that would otherwise apply.  It is
based on a use attainability demonstration and targets achievement of
the highest attainable use and associated criteria during the variance
period.

  Refer to Docket ID EPA-HQ-OW-2009-0596.

 EPA was not able to estimate costs for municipal stormwater systems
because the need for incremental controls is uncertain.

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Divide by 

Fraction 

Delivered

Divide by 

Average 

Streamflow

DPV 

for all Other

Reaches

DPV for Terminal 

Reaches

Estimate Protective

Load

