Siuslaw River, Oregon

Ocean Dredged Material Disposal Sites Evaluation Study and Environmental
Assessment

U.S. Army Corps of Engineers, Portland District

U.S. Environmental Protection Agency, Region 10

April 2010

Abbreviations and Acronyms

CFR		Code of Federal Regulations

cfs		cubic feet per second

cy		cubic yard(s)

CZMA		Coastal Zone Management Act

DMEF		Dredged Material Evaluation Framework

DPS		Distinct Population Segment

EA		Environmental Assessment

EFH		essential fish habitat

EPA		U.S. Environmental Protection Agency

ESA		Endangered Species Act

ESU		Evolutionarily Significant Unit

km		kilometers

m3		cubic meter(s)

mg/kg		milligrams per kilogram

mg/L		milligrams per liter

mm		millimeter(s)

MDL		method detection limit

MLLW		mean lower low water

MMPA		Marine Mammal Protection Act

MPRSA	Marine Protection, Research and Sanctuaries Act

MRL		method reporting limit

MSA		Magnuson-Stevens Fishery Conservation and Management Act

NAD		North American Datum

NEPA		National Environmental Policy Act

NHPA		National Historic Preservation Act

NMFS		National Marine Fisheries Service

OC		Oregon Coast (coho salmon)

ODMDS	ocean dredged material disposal site

ODFW		Oregon Department of Fish and Wildlife

OHV		off-highway vehicle

PAH		polynuclear aromatic hydrocarbon(s)

PCB		polychlorinated biphenyl(s)

ppb		parts per billion

ppm		parts per million

RM		river mile(s)

SEF		Sediment Evaluation Framework

SMMP		Site Management and Monitoring Plan

SONCC	Southern Oregon/Northern California Coast (coho salmon)

TOC		total organic carbon

TBT		tributyltin

ug/g		microgram per gram

ug/kg		micrograms per kilogram

ug/L		micrograms per liter

USACE	U.S. Army Corps of Engineers

U.S.C.		United States Code

ZSF		Zone of Siting Feasibility

Siuslaw River, Oregon

Ocean Dredged Material Disposal Sites

Evaluation Study and Environmental Assessment

Report Preparers

Wendy K. Briner	Biologist		CENWP-PM-E

Mark D. Siipola	Civil Engineer		CENWP-EC-HR

Timothy J. Sherman	Biologist		CENWP-EC-HR

Kim W. Larson	Fishery Biologist		CENWP-PM-E

Bert Rader	Archaeologist		CENWP-PM-E

Michael A. Martin	Archaeologist		CENWP-PM-E

Jonathan Freedman	Ocean Dumping Coordinator		EPA, Region 10

Jessica Winkler	Biologist		EPA, Region 10

Justine Barton	Ecologist		EPA, Region 10

Karen Bahus	Biologist/Writer		Consultant

Siuslaw River, Oregon

Ocean Dredged Material Disposal Sites

Evaluation Study and Environmental Assessment

Table of Contents

  TOC \o "1-1" \h \z \t "Heading 2,2,Heading 3,3"    HYPERLINK \l
"_Toc259180570"  PURPOSE AND NEED	  PAGEREF _Toc259180570 \h  1  

  HYPERLINK \l "_Toc259180571"  Need for Disposal Site Designation	 
PAGEREF _Toc259180571 \h  1  

  HYPERLINK \l "_Toc259180572"  Background	  PAGEREF _Toc259180572 \h  3
 

  HYPERLINK \l "_Toc259180573"  Offshore Designation and Disposal
History	  PAGEREF _Toc259180573 \h  4  

  HYPERLINK \l "_Toc259180574"  AFFECTED ENVIRONMENT	  PAGEREF
_Toc259180574 \h  7  

  HYPERLINK \l "_Toc259180575"  Physical Resources	  PAGEREF
_Toc259180575 \h  7  

  HYPERLINK \l "_Toc259180576"  General	  PAGEREF _Toc259180576 \h  7  

  HYPERLINK \l "_Toc259180577"  Siuslaw River Sediments	  PAGEREF
_Toc259180577 \h  7  

  HYPERLINK \l "_Toc259180578"  ODMDS Sediments	  PAGEREF _Toc259180578
\h  9  

  HYPERLINK \l "_Toc259180579"  Oceanographic Circulation	  PAGEREF
_Toc259180579 \h  11  

  HYPERLINK \l "_Toc259180580"  Surficial Geology	  PAGEREF
_Toc259180580 \h  11  

  HYPERLINK \l "_Toc259180581"  Water Quality	  PAGEREF _Toc259180581 \h
 11  

  HYPERLINK \l "_Toc259180582"  Biological Resources	  PAGEREF
_Toc259180582 \h  12  

  HYPERLINK \l "_Toc259180583"  Plankton and Fish Larvae	  PAGEREF
_Toc259180583 \h  12  

  HYPERLINK \l "_Toc259180584"  Benthic Invertebrates	  PAGEREF
_Toc259180584 \h  13  

  HYPERLINK \l "_Toc259180585"  Fish and Epibenthic Species	  PAGEREF
_Toc259180585 \h  14  

  HYPERLINK \l "_Toc259180586"  Commercial and Recreational Fisheries	 
PAGEREF _Toc259180586 \h  14  

  HYPERLINK \l "_Toc259180587"  Wildlife	  PAGEREF _Toc259180587 \h  15 


  HYPERLINK \l "_Toc259180588"  Threatened and Endangered Species	 
PAGEREF _Toc259180588 \h  15  

  HYPERLINK \l "_Toc259180589"  Socio-Economic Resources	  PAGEREF
_Toc259180589 \h  16  

  HYPERLINK \l "_Toc259180590"  Cultural Resources	  PAGEREF
_Toc259180590 \h  16  

  HYPERLINK \l "_Toc259180591"  Recreational Uses	  PAGEREF
_Toc259180591 \h  16  

  HYPERLINK \l "_Toc259180592"  Commercial Uses	  PAGEREF _Toc259180592
\h  17  

  HYPERLINK \l "_Toc259180593"  ANALYSIS OF ALTERNATIVES	  PAGEREF
_Toc259180593 \h  17  

  HYPERLINK \l "_Toc259180594"  No Action Alternative	  PAGEREF
_Toc259180594 \h  18  

  HYPERLINK \l "_Toc259180595"  Upland Disposal Alternative	  PAGEREF
_Toc259180595 \h  18  

  HYPERLINK \l "_Toc259180596"  Estuarine Disposal Alternative	  PAGEREF
_Toc259180596 \h  18  

  HYPERLINK \l "_Toc259180597"  Ocean Disposal Alternatives	  PAGEREF
_Toc259180597 \h  19  

  HYPERLINK \l "_Toc259180598"  Disposal Off the Continental Shelf	 
PAGEREF _Toc259180598 \h  19  

  HYPERLINK \l "_Toc259180599"  Continued Use of Existing Sites	 
PAGEREF _Toc259180599 \h  20  

  HYPERLINK \l "_Toc259180600"  Designation of New ODMDS	  PAGEREF
_Toc259180600 \h  20  

  HYPERLINK \l "_Toc259180601"  ANALYSIS OF OCEAN DUMPING SITE
DESIGNATION PROCESS AND ENVIRONMENTAL EFFECTS	  PAGEREF _Toc259180601 \h
 21  

  HYPERLINK \l "_Toc259180602"  Overview	  PAGEREF _Toc259180602 \h  21 


  HYPERLINK \l "_Toc259180603"  Defining a Zone of Siting Feasibility	 
PAGEREF _Toc259180603 \h  21  

  HYPERLINK \l "_Toc259180604"  Siuslaw River Zone of Siting Feasibility
  PAGEREF _Toc259180604 \h  22  

  HYPERLINK \l "_Toc259180605"  Regulatory Criteria for Ocean Disposal
Site Selection	  PAGEREF _Toc259180605 \h  23  

  HYPERLINK \l "_Toc259180606"  Application of Four General Criteria (40
CFR 228.5)	  PAGEREF _Toc259180606 \h  23  

  HYPERLINK \l "_Toc259180607"  Application of Eleven Specific Factors
(40 CFR 228.6)	  PAGEREF _Toc259180607 \h  29  

  HYPERLINK \l "_Toc259180608"  SUMMARY OF COORDINATION UNDER OTHER
APPLICABLE FEDERAL STATUTES	  PAGEREF _Toc259180608 \h  37  

  HYPERLINK \l "_Toc259180609"  Federal Action	  PAGEREF _Toc259180609
\h  37  

  HYPERLINK \l "_Toc259180610"  Public Comments	  PAGEREF _Toc259180610
\h  37  

  HYPERLINK \l "_Toc259180611"  Endangered Species Act	  PAGEREF
_Toc259180611 \h  37  

  HYPERLINK \l "_Toc259180612"  Magnuson-Stevens Fishery Conservation
and Management Act	  PAGEREF _Toc259180612 \h  39  

  HYPERLINK \l "_Toc259180613"  Marine Mammal Protection Act	  PAGEREF
_Toc259180613 \h  39  

  HYPERLINK \l "_Toc259180614"  Coastal Zone Management Act	  PAGEREF
_Toc259180614 \h  40  

  HYPERLINK \l "_Toc259180615"  National Historic Preservation Act	 
PAGEREF _Toc259180615 \h  40  

  HYPERLINK \l "_Toc259180616"  Tribal Consultation	  PAGEREF
_Toc259180616 \h  40  

  HYPERLINK \l "_Toc259180617"  SELECTION OF OCEAN DISPOSAL SITES FOR
FORMAL DESIGNATION	  PAGEREF _Toc259180617 \h  40  

  HYPERLINK \l "_Toc259180618"  LITERATURE CITED	  PAGEREF _Toc259180618
\h  41  

 

List of Tables

  TOC \h \z \c "Table"    HYPERLINK \l "_Toc238780192"  Table 1. 
Siuslaw River Project Dredging Volumes	  PAGEREF _Toc238780192 \h  5  

  HYPERLINK \l "_Toc238780193"  Table 2.  Proposed Siuslaw North and
South ODMDS Conflict Matrix	  PAGEREF _Toc238780193 \h  24  

 

List of Figures

  TOC \h \z \c "Figure"    HYPERLINK \l "_Toc248551974"  Figure 1. 
Siuslaw River Proposed North ODMDS and South ODMDS	  PAGEREF
_Toc248551974 \h  2  

  HYPERLINK \l "_Toc248551975"  Figure 2.  Historical Siuslaw River
Ocean Disposal Sites	  PAGEREF _Toc248551975 \h  5  

  HYPERLINK \l "_Toc248551976"  Figure 3.  Siuslaw Ocean Disposal Sites
Sampling Locations, 2008	  PAGEREF _Toc248551976 \h  10  

  HYPERLINK \l "_Toc248551977"  Figure 4.  Overlay Evaluation of
Individual Resources	  PAGEREF _Toc248551977 \h  27  

 

Technical Appendices

Appendix A – Living Resources

Appendix B – Physical Processes and Geological Features

Appendix C – Sediment and Water Quality

Appendix D – Cultural Resources

Appendix E – Recreational Resources

Appendix F – Site Management/Monitoring Plan

PURPOSE AND NEED

This Ocean Dredged Material Disposal Site (ODMDS) Evaluation and
Environmental Assessment (EA) was jointly prepared by the U.S. Army
Corps of Engineers (USACE) and the U.S. Environmental Protection Agency
(EPA).  The purpose of this evaluation is to provide documentation in
support of final EPA designation of two ODMDS (North and South) located
offshore from the Siuslaw River, Oregon (Figure 1).  These sites are
needed for long-term use by the USACE for the federally authorized
Siuslaw River navigation project and for use by others for disposal of
dredged material meeting ocean disposal criteria.  This evaluation will
assess the proposed final designation of the two Siuslaw sites against
the statutory requirements set forth in the Marine Protection, Research
and Sanctuaries Act, as amended (MPRSA), 33 U.S.C. 1401 to 1445, and the
regulations found in Part 228 of Title 40 of the Code of Federal
Regulations (CFR).  These regulations were promulgated in accordance
with criteria set out in Sections 102, 103 and 104 of the MPRSA.  This
evaluation also outlines EPA’s coordination under the National
Environmental Policy Act of 1969 (NEPA), 42 U.S.C. Sections 4321 to
4370f; Endangered Species Act of 1973 (ESA), 16 U.S.C. Sections 1531 to
1599; Magnuson-Stevens Fishery Conservation and Management Act (MSA), 16
U.S.C. Sections 1801 et seq.; Marine Mammal Protection Act of 1972
(MMPA), 16 U.S.C. Sections 1361 et seq.; National Historic Preservation
Act of 1966 (NHPA), 16 U.S.C. Sections 470 et seq.; and the Coastal Zone
Management Act of 1972 (CZMA), 16 U.S.C. Sections 1451 to 1466, all as
amended.

Need for Disposal Site Designation

The EPA undertook this evaluation to determine whether to designate any
dredged material disposal site(s) near the mouth of the Siuslaw River
pursuant to its authority under the MPRSA at Section 102(c) in response
to several factors.  These factors include:

The prohibition on further use of the existing Siuslaw Section 103
disposal sites following the close of the 2009 dredging season pursuant
to USACE site selection authority under MPRSA Section 103(b), which
allows the USACE to select a site under Section 103 for a period of 5
years with a maximum 5-year extension with EPA concurrence;

The understanding that in the absence of an EPA-designated disposal site
or sites, any necessary open-water disposal would either be precluded or
the USACE would have to undertake additional short-term site selections,
perhaps a number of them, in the future;

The clear Congressional preference expressed in MPRSA Section 103(b)
that any open-water disposal of dredged material take place at
EPA-designated sites, if feasible; and

The statutory preference to concentrate, where feasible, any open-water
disposal at sites that have been used historically, see 40 CFR 228.5(e).

Figure   SEQ Figure \* ARABIC  1 .  Siuslaw River Proposed North ODMDS
and South ODMDS

The EPA’s evaluation considered whether there was a need for any
disposal site designations for long-term dredged material disposal,
including an assessment of whether other dredged material management
methods and/or disposal options could reasonably be judged to obviate
the need for such designations.  Having concluded that there was a need
for open-water disposal sites, EPA then assessed whether there were
sites that would satisfy the applicable environmental criteria to
support a site designation under the MPRSA Section 102(c).

Background

The MPRSA was passed by Congress in recognition of the fact that the
disposal of material into ocean waters could potentially result in
unacceptable adverse environmental effects.  Under the MPRSA, the EPA
and the USACE were assigned responsibility to regulate the dumping of
dredged material into ocean waters and to prevent or strictly limit the
dumping into ocean waters of any material that would “unreasonably
degrade or endanger human health, welfare, or amenities, or the marine
environment, ecological systems, or economic potentialities.”

The EPA administers and enforces the overall permit program for ocean
disposal of material other than dredged material and designates dredged
material disposal sites.  The USACE, with EPA’s concurrence, issues
permits for the disposal of dredged material for the purpose of ocean
disposal where the USACE determines that dumping will not unreasonably
degrade the environment or endanger human health, welfare, or amenities,
or the marine environment, ecological systems, or economic
potentialities.  While the USACE does not administratively issue itself
a permit, the requirements that must be met before dredged material
derived from USACE projects can be disposed into ocean waters are the
same as those where a permit would be issued.

The EPA must consider statutory criteria and evaluate the four general
regulatory criteria codified at 40 CFR§ 228.5 and the eleven specific
regulatory criteria at 40 CFR § 228.6.  Pursuant to Section 102(c) of
the MPRSA, the EPA is responsible for designating sites for the disposal
of dredged material.  The USACE is allowed, with EPA’s concurrence, to
select a site for ocean disposal of dredged material pursuant to Section
103(b) and (c) of the MPRSA, when a feasible disposal site has not been
designated by EPA, or when the continued use of an alternative site is
necessary to maintain navigation and facilitate interstate or
international commerce, and EPA has determined that the alternative site
does not pose an unacceptable risk to human health, aquatic resources,
or the environment.

An EPA-designated site requires a site management and monitoring plan
(SMMP).  Use of a designated site is subject to the restrictions
included in the SMMP and EPA’s designation regulations.  These
restrictions are based on an in-depth evaluation of the site and
potential disposal activity, as well as public review and comment.

Designation of an ODMDS in itself does not result in disposal of dredged
material.  A separate evaluation of the suitability of dredged material
for ocean disposal must be undertaken for each proposed use of the site
by either the USACE or non-USACE permit applicant.  Typically, this
involves evaluation of the specific disposal activity under the criteria
(which can include multiple years of use), circulation of a public
notice, specific coordination with stakeholders, and concurrence by the
appropriate EPA region.

The EPA proposes to designate two ocean disposal sites, the North ODMDS
and South ODMDS, which are located approximately 1 mile offshore of the
entrance to the Siuslaw River (see Figure 1).  The proposed North site
is 4,800 feet by 2,000 feet, and, based on 2009 bathymetric data, ranges
from 30 to 115 feet deep. The proposed South site is 3,000 feet by 2,000
feet and ranges in depth from 80 to 120 feet deep. 

Offshore Designation and Disposal History

An Interim ocean disposal site, or areas in the same vicinity, have been
used by the USACE Portland District since 1929, when hopper dredges
began to work the Siuslaw bar and entrance channel.  The Interim ODMDS
(Interim Site A on Figure 2) was designated an EPA Interim Site in 1977
(40 CFR 228.12) and was used from 1977 to 1996.  It was suspected that
ocean currents were transporting dredged material placed in the Interim
site back into the Siuslaw entrance channel.  In 1986-1987, the USACE
completed dye and seabed drifter studies (USACE 1988).  Results
demonstrated dredged material deposited south and/or east of the
centroid of the interim site, with prevailing north to northwest winds,
could possibly drift back across or into the Siuslaw entrance channel. 
The Interim site also experienced mounding to 14 feet relative to the
1981 bathymetry due to its small size and the volume dredged.  To
address these issues, two adjusted and expanded ocean disposal sites,
ODMDS B and C, were selected by the USACE under Section 103 of the MPRSA
(Figure 2, Sites B and C).  Site B includes a portion of Interim Site A.
Material removed from the Siuslaw federal navigation project was first
deposited at Site C in 1997, while Site B was first used in 1999. Since
1997, material removed from the Siuslaw federal navigation project has
only been deposited into ODMDS B and C (see Table 1).

Sites B and C experienced some mounding even though disposal
restrictions were used to enhance dispersal. The Interim Site A vicinity
of Site B was avoided until previously placed materials could disperse.
As a result of the larger sites, reduced overall volumes of dredging and
disposal, and avoidance of the Interim Site A corner, all disposal
restrictions were lifted in 2008. Pending final designation by EPA, in
2004 the USACE extended the selection of ODMDS B and C for a final
5-year period.  Following expiration, the EPA must designate ocean
disposal sites under Section 102 of the MPRSA in order for dredged
material to be disposed offshore of the Suislaw River. 

Table 1 presents the volume of material placed offshore of the Siuslaw
River. The bulk of the material dredged has been placed in the larger
Site B. Quantities of dredging overall have dropped and future dredged
material disposal volumes are not often expected to exceed 100,000 cubic
yards (cy) annually (based on a 13-year average of about 60,000 cy and a
range of 22,300-117,300 cy). Material is expected to be disposed over a
period of 20 days of dredging and disposal (average is about 7 days;
range 3-23 days).  Generally, dredging and disposal are expected to
occur between June 1 and October 31 of each year.

Figure   SEQ Figure \* ARABIC  2 . Historical Siuslaw River Ocean
Disposal Sites

 Table   SEQ Table \* ARABIC  1 .  Siuslaw River Project Dredging
Volumes

Fiscal Year	Dredging

Volumes (x 1,000 cy)

1929-1977	2,800.0*

1977	139.3*

1978	191.4*

1979	246.6*

1980	94.2*

1981	388.4*

1982	193.4*

1983	213.3*

1984	221.1*

1985	271.2*

1986	218.8*

1987	215.8*

1988	114.5*

1989	116.8*

1990	99.0*

1991	65.9*

1992	194.2*

1993	239.6*

1994	223.3*

1995	121.6*

1996	84.8*

1997	40.0 (Site C)

1998	69.6 (Site C)

1999	43.5 (Site B)

2000	55.1 (Site C)

2001	101.2 (Site C)

2002	117.3 (Site B)

2003	55.0 (Site B)

2004	14.1 (Site B) & 9.0 (Site C)

2005	33.4 (Site B)

2006	22.3 (Site B)

2007	76.0 (Site B)

2008	69.9 (Site B)

2009	91.7 (Site B)



* Dredged material from 1977 to 1996 was placed in the EPA-designated
Interim ODMDS (Site A).

At other ocean disposal sites along the Oregon Coast, the EPA and the
USACE have found that the strategy of placing a site to the north and
another to the south of the river mouth has worked well (Coos Bay,
Umpqua, etc.), primarily because it allows for adaptive management of
the sites given a dynamic current environment.  Similarly, EPA is
proposing two expanded ocean disposal sites located North and South of
the mouth of the Siuslaw River. Generally, material placed deeper than
60 feet is less mobile and less available to the active littoral system.
 To keep more material in the active littoral system, EPA proposes a
North site configuration that expands the existing Section 103 Site B to
include the original 1977 Interim site (Site A), and a similar
relatively “shallow” area to the north of Site A (see Figure 2). 
Based on likely northerly movement of coastal littoral material over the
course of the yearly dredging and disposal cycle, the EPA proposes to
utilize the shallower portions of the North site to the maximum extent
possible in order to disperse material into the active littoral zone,
limit wave effects due to mounding, and keep material from reentering
the navigation channel to the south.  The proposed South site’s
southern boundary was moved further south, doubling the size of the
site, to allow for better dispersal should that site be needed. To
support annual adaptive management of the sites, EPA anticipates annual
bathymetric surveys and other management and monitoring at the proposed
North and South sites in accordance with the Site Management and
Monitoring Plan (SMMP) (see Appendix F). 

AFFECTED ENVIRONMENT

Physical Resources

General

This section provides a summary characterization of the physical
resources in the Siuslaw River study area.  Additional information is
provided in Appendix B: Physical Processes and Geologic Features.  The
Siuslaw River estuary covers about 1,780 acres and opens into the
Pacific Ocean about 160 miles south of the mouth of the Columbia River. 
It lies within the Heceta Head littoral cell, which extends for about 56
miles from Heceta Head south to Cape Arago.  The estuary is fed mainly
by Siuslaw River, which is 108 miles from its mouth to headwaters and
has a drainage basin of 773 square miles.  The watershed encompasses
part of the Coast Range, with the Siuslaw River extending inland to
Cottage Grove.  The coastal zone of the littoral cell consists of a wide
plain that is 1- to 2-miles wide, covered by active and stabilized sand
dunes backed by the mature upland topography of the Coast Range.  The
lower portion of the Siuslaw River is bordered by broad alluvial flats. 
Between the Siuslaw River and Yaquina River estuaries, the continental
shelf is at its widest along the Oregon Coast, extending over 44 miles
offshore forming the Heceta Bank.  Just south of the Siuslaw River, the
shelf begins to narrow and is only about 19 miles wide at the mouth of
the Umpqua River.  At the mouth of the Siuslaw River, the first 2 miles
or so of the shelf is covered with sand.  From there a thin layer of mud
(about 1-inch thick) mantles the surface.

The Heceta Head littoral cell is the largest on the Oregon Coast. 
Landward of the cell, the coast is primarily beach-fronting sand dunes. 
Headlands are located at the north and south landward ends of the cell. 
Three major river systems enter the cell.  From north to south, these
are the Siuslaw River, the Umpqua River (largest of the three), and the
Coos River.

Siuslaw River Sediments

This section provides a summary characterization of the sediments to be
dredged from the Siuslaw River.  Additional information is provided in
Appendix C.  In 1991, the USACE collected 10 sediment samples from the
Siuslaw River federal navigation channel for physical analysis; one
sample from the turning basin at river mile (RM) 5.0 near Florence was
subjected to chemical analyses (USACE 1991).  Sediments were found to be
99.9% poorly graded sand with low volatile solids content (1.1%).  The
median grain size of 0.32 millimeters (mm) was that of medium sand.  The
results of the chemical analysis from the turning basin had metals
concentrations below established levels of concern.  No pesticides,
polychlorinated biphenyls (PCBs), polynuclear aromatic hydrocarbons
(PAHs), or phenols were detected.

In 1996, 10 surface grab samples were collected from the entrance to RM
8 (USACE 1996).  These samples were subjected to physical tests, with
grain-size ranging from 100% to 92.7% (mean 98.6%) poorly graded sand
with volatile solids content ranging from 1.4% to 0.3% (mean 0.8%).  The
mean grain-size was that of medium sand (0.294 mm).

In 2001, eight surface grab samples were collected from the entrance to
RM 6 (USACE 2001).  All samples were submitted for physical analyses,
with grain-size ranging from 100% to 97.9% (mean 99.2%) poorly graded
sand with volatile solids content ranging from 0.42% to 3.0% (mean
1.29%).  The mean grain-size was that of medium sand (0.29 mm).  Two
samples were selected for chemical analyses to include metals, total
organic carbon (TOC), PCBs, chlorinated hydrocarbons, phenols,
phthalates, miscellaneous extractables, and PAHs; one sample was
submitted for organotin (TBT - pore water method) analysis.  The samples
submitted for chemical analysis were taken from the federal channel near
the outfall to the sewage treatment plant and near the boat dock.  The
one sample analyzed for TBT was collected near the boat dock.  Sediment
represented by these samples would meet the marine screening level
guidelines established in the Sediment Evaluation Framework (SEF 2009)
for unconfined in-water placement without further characterization.

In August 2006 (Sherman 2007), seven samples were collected from the
Siuslaw entrance to RM 5.  All samples were submitted for physical
analyses, with grain-size ranging from 98.5% to 95.4% poorly graded sand
(mean 97.1%), with volatile solids content ranging from 0.69% to 2.24%
(mean 1.14%).  One sample was selected for chemical analyses to include
metals, TOC, PCBs, chlorinated hydrocarbons, phenols, phthalates,
miscellaneous extractables, and PAHs.  Two samples were submitted for
TBT analysis, one from the turning basin adjacent to the marina and the
second from the federal channel by the fuel dock.  Pore-water TBT was
not analyzed due to insufficient pore-water volume in the samples, a
result of the high sand content.  The chemical analyses showed only low
levels of contamination in any of the samples, with all levels well
below their respective SEF screening levels.  No pesticides, PCBs, PAHs,
chlorinated hydrocarbons, or miscellaneous extractables were detected in
any of the samples.  Several metals, phthalates, phenol, and dibutyltin
were detected, but at low levels and well below their respective
screening levels.  Detection levels were sufficiently low to evaluate
material proposed for dredging.  The analytical results of this
characterization are consistent with historical data.  Sediment
represented by these samples met the marine screening levels guidelines
established in the SEF for unconfined in-water placement without further
characterization.

Sediments were collected in October 2006 from the Port of Siuslaw marina
and from the upper river channel (RM 5 to 16.5). These samples are
considered representative of the material from these areas, though
dredging above RM 5 is very infrequent. Sediment from the Port’s
marina ranged in grain-size from 47.3% to 79.4% sand (mean 75.9%), while
sediment from the upper river channel ranged from 93.6% to 97.0% sand
(mean 95.4%). Sixteen samples were submitted for physical testing and
eight samples (two upstream and six marina) were subjected to chemical
analysis, including metals, PCB’s, pesticides, chlorinated
hydrocarbons, miscellaneous extractables, phthalates, phenols, and low
and high molecular weight PAH’s. The six marina samples were also
tested for bulk and porewater TBT. Some samples contained low levels of
several COC’s, however, none approached their DMEF/SEF screening
levels, with all laboratory detection levels and quality controls at
acceptable levels.  

ODMDS Sediments

This section provides a summary characterization of the sediments in the
ocean environment offshore of the Siuslaw River.  Additional information
is provided in Appendix C.  In August 2008, 10 surface-grab sediment
samples were collected at ODMDS B and C (proposed North and South sites)
with a 0.96 m2 modified Gray-O’Hara box core sampler (Figure 3). 
Three samples (01, 02 and 03) were collected from east to west on the
centerline of Site B.  Three samples (07, 08 and 09) were collected from
east to west on the centerline of Site C.  Four reference samples were
collected north, south, and between Sites B and C (04, 05, 06, and 10). 
All samples were subjected to physical/chemical analysis.

Physical Analysis and TOC.  The mean value for a grain-size of sand or
greater was 97.25% with a mean value of 3.71% fine-grained material
(less than 230 sieve); mean value for TOC was 0.107%.

Metals.  Sediments were analyzed for 10 metals.  Of these, all but
antimony (Sb), silver (Ag), and mercury (Hg) were present in all of the
samples.  No detected metal values approached their respective SEF
marine screening levels.

Pesticides/PCBs.  Chlordane was reported as technical chlordane in one
sample (01), and alpha and gamma Chlordane in three samples (01, 02,
06).  Detection levels for technical chlordane were problematic, with
non-detects reported at levels above the SEF marine screening levels.
These values were not supported by the values found for alpha and gamma
chlordane where levels separately and additively were well below the SEF
marine SL. In addition, the estimated and non-detect values are all
below the SL of 10 ug/kg currently used for decision-making in Puget
Sound (where total chlordane is defined as the sum of cis-chlordane,
trans-chlordane, cis-nonachlor, trans-nonachlor and oxychlordane). Other
than chlordane, all other pesticide values were below method reporting
levels and well below SEF marine screening levels.  No PCBs were
detected.



Figure   SEQ Figure \* ARABIC  3 .  Siuslaw Ocean Disposal Sites
Sampling Locations, 2008

Chlorinated Hydrocarbons, Phthalates, Phenols, and Miscellaneous
Extractables.  No chlorinated hydrocarbons were detected.  Several
phthalates, miscellaneous extractables, and phenols were detected at
very low levels; all were below their respective SEF marine screening
levels.

PAHs.  Various “low molecular weight” and “high molecular
weight” PAHs were detected, but at very low levels and well below
their respective SEF marine screening levels.

Oceanographic Circulation

Coastal circulation offshore of the Siuslaw River is directly influenced
by large-scale regional currents and weather patterns in the
northwestern Pacific Ocean.  During winter, strong low-pressure systems
with winds and waves predominantly from the southwest, initiate strong
northward currents.  During summer, high-pressure systems dominate and
consequently, waves and wind are commonly from the north.  In both
seasons, there are short-term fluctuations related to local wind, tidal
and bathymetric effects.  Along the Oregon Coast, there is a southerly
wind in summer which creates a mass transport of water offshore
resulting in upwelling of bottom water nearshore. 

In 1985 (see Appendix B), monitoring of currents in the Siuslaw
nearshore area showed that summer currents were more frequently to the
north and were generally the stronger currents.  There were
onshore-offshore currents during the summer with speeds equal to or
greater than 1 foot/second.  Bottom currents in the winter had a strong
offshore component.  The largest percentage of the winter currents was
to the north with the majority of the speeds equal to or greater than 1
foot/second.  Appendix B provides details of the sediment transport
processes for the Siuslaw River and nearshore area.

Surficial Geology

The geological data collected in 2008 for the ODMDS area showed the mean
value for a grain-size of sand was 97.25% with a mean value of 3.71%
fine-grained material.  Sediments dredged from the Siuslaw River
entrance channel are similar to the offshore sediments.  Grain-size
analyses for these sediments in 2006 resulted in mean values of 0.2%
gravel (shell hash, 0.0% - 0.5% range), 97.1% sand (95.4% - 98.5%
range), and 2.7% silt/clay (1.5% - 4.1% range).

Water Quality

Water quality throughout the action area is expected to be typical for
seawater of the Pacific Northwest.  There is no reason to expect
significant chemical contamination in either the water or sediments, as
few industries are located along the estuary.  A large data set
regarding the impact of dredged material disposal on the water column
was accumulated in the early 1980s, and focus has shifted away from the
water column pathway to one having more direct contact with bulk or
suspended sediment.  Currently, water column tests are rarely performed
unless there is a “reason to believe” a water column release may
occur. 

In the summer of 2002, oxygen levels in the water near the Oregon coast
plunged so low that fishes, crabs, and other marine organisms had to
flee or die in the suffocating waters (PISCO 2009).  These low oxygen
conditions, commonly called hypoxia, had never been documented in Oregon
prior to 2002, but have recurred every summer since.  The most severe
event occurred in the summer of 2006 when oxygen levels dropped to
historic lows and hypoxic water could be found in large areas along the
Washington and Oregon coasts.  In 2006, the dead zone lasted 4 months
and large areas of the coastal ocean were affected by oxygen levels that
dropped as low as zero.  It is normal to find naturally low-oxygen
conditions in deep, offshore waters, e.g., at the edge of the
continental shelf and slope.  However, the occurrence of low-oxygen
water close to shore (the inner shelf, less than 165’ of water) is
highly unusual and had not been reported prior to 2002, despite over 50
years of scientific observations along the Oregon coast.  No evidence of
impacts due to hypoxia have been documented in over 34 years of studies
at the various ODMDSs off the Oregon coast.

Biological Resources

This section summarizes biological conditions in the ocean environment
offshore of the Siuslaw River.  Additional information is provided in
Appendix A.

Plankton and Fish Larvae

No specific data is available for zooplankton in the Siuslaw River
nearshore area.  However, Keister and Peterson (2003) provided a
discussion of the zooplankton community found off the central Oregon
Coast (along the Newport hydrographic line).  They indicated that the
zooplankton community is influenced strongly by seasonal variations in
wind and current patterns.  During late spring and summer, northwesterly
winds set up flow towards the equator and coastal upwelling. 
Northwesterly winds dominate from April/May-September; periodic
relaxations or southwesterly storms rapidly affect the hydrograph of
nearshore areas.  During this time period conditions about 30 kilometers
(km) offshore are less variable.  Boreal neritic copepods such as
Pseudocalanus mimus, Calanus marshallae, Centropages abdominalis,
Acartia longiremis, and Acartia hudsonica dominate the coastal plankton
during summer (Peterson and Miller 1977).  In early fall, winds reverse
and upwelling ceases; during autumn and winter, winds are predominantly
southwesterly, the Davidson Current flows toward the pole, and offshore
surface waters are transported onshore.  In winter, the coastal
zooplankton is populated by warm-water species such as Mesocalanus
tenuicornis, Paracalanus parvus, Ctenocalanus vanus, Clausocalanus spp.,
Acartia tonsa, and Corycaeus anglicus (Peterson and Miller 1977).

Auth and Brodeur (2006) examined ichthyoplankton off the central Oregon
Coast (along the Newport hydrographic line).  The dominant taxa
collected were northern anchovy (Engraulis mordax), slender sole
(Lyopsetta exilis), rockfishes (Sebastes spp.), northern lampfish
(Stenobrachius leucopsarus), and blue lanternfish (Tarletonbeania
crenularis).  Total larval concentration increased from 49.3 per 1,000
cubic meters (m3) in 2000 to 72.0 per 1,000 m3 in 2002, with seasonal
concentrations highest in August 2000 (90.3 per 1000 m3) and April 2002
(151.2 per 1,000 m3).  Relatively few larvae were found at depths
greater than 100 meters, while highest larval concentrations generally
were observed from depths of 0 to 50 meters.  Larval diversity and
concentration were higher offshore (46-84 km off the coast) than in
nearshore areas (9-28 km off the coast).  Highest concentrations were
normally found at an intermediate station, approximately 65 km off the
coast.  Species designated as either coastal or offshore species by
previous studies were predominantly found in their respective shelf
regions.  Most larval concentrations were positively correlated with
temperature and negatively correlated with salinity.

Auth and others (2007) examined the ichthyoplankton assemblages from a
single station 69 km off Heceta Head on the central Oregon Coast.  The
authors noted that the species composition, assemblages, and dominant
taxa were similar to those found in other studies conducted in this area
during summer (Richardson 1973; Richardson and Pearcy 1977; Brodeur et
al., 1985; Auth and Brodeur 2006).  This similarity provided evidence to
support the hypothesis of Auth and Brodeur (2006) that past sampling
along the Newport hydrographic line during summer is representative of
ichthyoplankton assemblages elsewhere along the Oregon Coast.

Benthic Invertebrates

Field sampling in October 1984 and January 1985 gathered information on
benthic invertebrates at 14 stations off the mouth of the Siuslaw River
(USACE 1992).  Another benthic study was conducted at 11 offshore
stations in September 1988 (USACE 1992).  During these studies, the
Siuslaw offshore area exhibited diverse benthic invertebrate
communities.  A total of 135 taxa were collected in October 1984, 106
taxa in January 1985, and 163 taxa in 1988.  Densities were very similar
in 1984 and 1985, with approximately 2,200 individuals/m2 collected.  An
average of 4,445 individuals/m2 was collected in the 1988 survey. 
Polychaetes (annelid worms) were the numerically dominate species
collected during the 1984-1985 sampling periods.  Scoloplos armiger,
Chaetozone setosa, and Megelona sacculata were the dominant polychaete
species, reaching densities of approximately 2,500/m2, 1,500/m2, and
1,400/m2, respectively.  Other dominant species collected included the
amphipods Eohaustorius sencillus, Mandibulophoxus gelesi, and E.
sawyeri.  The area also had a large number of sand dollars, Dendraster
excentricus.  In 1988, the dominant polychaete species was Owenia
fusiformis, although the density of this polychaete was low to moderate
when compared to other coastal areas.  Another dominant polychaete
collected was Spiophanes bombyx.

Field surveys were conducted in August and September 2008 by Marine
Taxonomic Services (USACE 2009) to supplement earlier benthic
invertebrate data and provide current information on fish and epibenthic
species present in the area of the proposed Siuslaw ocean disposal
sites.  The benthic invertebrate fauna in the vicinity of the proposed
sites was found to be typical of the nearshore, high-energy environment
found along the Oregon Coast.  The density distribution data indicated
large juvenile recruitment of most species from spring spawning.  This
recruitment includes both opportunistic short-lived species (Spiophanes
bombyx) and longer-lived species (razor clams, Siliqua sp. juv. and
Dendraster excentricus).  The large recruitment of these longer-lived
species and the recruitment of some shorter-lived species, mostly
polychaeta and crustacea, indicate good ocean conditions in the spring
and summer months in this area.  The crustaceans showed some population
spikes throughout the data; however, the same species were not always
the driving factors.  Gammarid amphipods were often present but also
present were Diastylopsis dawsoni (Cumacea) and barnacles (Cirripedia),
which showed up on hard features such as snail shells and the occasional
rock.  The echinoderms were driven by Dendraster sp. juv/Dendraster
excentricus and the other miscellaneous groups were largely populated by
Nemertinea and juvenile holothuroids.

The benthos in the Siuslaw nearshore area is typical of the communities
found near other ocean disposal sites along the Oregon Coast, such as
Coos Bay sites E and F, Umpqua River, Rogue River, and Chetco River
(Hancock et. al., 1981; USACE 1985, 1988a, 1988b, 1990).  This benthic
community, largely dominated by very mobile organisms, provides an
important link in the marine food web.  These organisms serve as a
direct food source for other benthic organisms and demersal fishes. 
They also play an active role in the breakdown of organic debris and the
tube-building species that help stabilize the marine sediments.  Many of
the benthic species in the area are able to survive in this dynamic
environment being either very mobile or being able to react both to
natural or man-made perturbations.  The benthic community would be
expected to re-colonize within a period of a few weeks to months after
disposal (USACE 1993).

Fish and Epibenthic Species

Commercially and recreationally important epibenthic species in the
Siuslaw nearshore area are shellfish and Dungeness crab (Cancer
magister).  Clam beds are located on the north side of the Siuslaw
estuary at RM 1.  Gaper clams (Tresus capex) are the dominant bivalves
harvested in this area.  Dungeness crab adults occur on sandflat habitat
along the entire Oregon Coast.  They spawn in offshore areas and occur
in the estuary when conditions are favorable in late summer and fall.

The nearshore area has been known to be a squid spawning area with the
location and size varying annually (USACE 1992).  Although there have
been incidental catches of squid within 1.5 nautical miles of the mouth
of the Siuslaw, there has been no directed squid harvest within this
area.  There have been reports of egg capsules and adults caught in
trawls, as well as the presence of egg capsules on crab gear.  Outside
of the 1.5 nautical mile radius from the mouth, there have been directed
squid harvests south of Heceta Head to Cape Perpetua.  Squid spawn
between water depths of 5 to 40 meters, with maximum spawning occurring
at 15 meters.  After hatching, they school in the middle of the water
column, moving toward the surface as they mature.  Mature squid feed
mostly at water depths of 20-50 meters (USACE 1992).

The nearshore area off the Siuslaw River supports anadromous salmonids
including coho salmon, winter steelhead, and spring and fall Chinook
salmon, as well as a variety of other pelagic and demersal fish species.
 Other pelagic species include the Pacific herring (Clupea harengus
pallasi), northern anchovy (Engraulis mordax), and surf smelt (Hypomesus
pretiosus).

Demersal species present in the nearshore area are mostly residents and
include a number of sculpins, sea perch, and rockfish species associated
rocky habitats, as well as flatfish species occurring predominantly over
open sandflats.  Flatfish include English sole (Parophrys vetulus),
sanddab (Citharichthys sp.), and starry flounder (Platichthys
stellatus).  English sole and starry flounder, along with the sand sole
(Psettichthys melanostictus), spawn in the inshore area in the summer
and juveniles of these, as well as other marine species, may rear in the
Siuslaw estuary.

Commercial and Recreational Fisheries

Based on data from NMFS (2006) for commercial fishing, a total of 38
commercial vessels delivered landings to Florence in 2000.  Landings
were in the following West Coast fisheries (data shown represents
landings in metric tons/value of landings/number of vessels landing): 
crab (112.8/$562,057/10), groundfish (124.3/$442,781/15), highly
migratory species (6.9/$11,712/5), salmon (29.7/$113,885/22), shrimp
(35.7/$28,529/5), and other species (1.5/$6808/5).  There were no fish
processors operating in Florence in 2000.  A total of 41 commercial
vessels were owned by Florence residents in 2000, 19 of which
participated in the federally managed groundfish fishery.  Recreational
fishing takes place in the same general areas as the commercial fishery
but usually closer to shore.  For the port complex around Florence, the
2000 recreational salmonid catch in the ocean boat fishery was 250
Chinook salmon and 472 coho salmon.  The recreational non-salmonid catch
was a total of 213 fish.  The top species landed, in order, included
greenstripe, canary, and yelloweye rockfish, and Pacific halibut.

Wildlife

Steller sea lions, harbor seals, and California sea lions are present
most of the year in the Siuslaw nearshore area.  Steller sea lions
forage at river mouths and nearshore areas along the Oregon Coast. 
Harbor seals breed in the estuary and on nearshore rocks.  The Siuslaw
nearshore area and shoreline provides important habitat for shorebirds,
waterfowl, herons, bald eagles, hawks, and many other species of birds. 
Pelagic birds (e.g., murres, auklets, cormorants) are likely to use the
area near the proposed Siuslaw ocean disposal sites and adjacent waters
for foraging.

Threatened and Endangered Species

Oregon Coast (OC) coho salmon is a federally threatened species that may
be present in the vicinity of the proposed Siuslaw ocean disposal sites.
 The Siuslaw River and estuary are designated as critical habitat for
this species, but the ocean area off the Siuslaw River is not designated
critical habitat.  Coho salmon are present in the vicinity of the
proposed ocean disposal sites as both adults and juveniles.  Adults hold
in the offshore area prior to entering the estuary to migrate up river
to spawn.  Juveniles rear in the nearshore ocean area after migrating
downstream and transitioning to saltwater.  Upstream migration of adult
coho salmon generally takes place from August through November. 
Juvenile outmigration extends from April through June, but peaks in May.

The Southern Oregon/Northern California Coast (SONCC) coho salmon is
also federally threatened and includes all naturally spawned populations
of coho in coastal streams between Cape Blanco, Oregon, and Punta Gorda,
California.  The proposed Siuslaw ocean disposal sites are not located
within designated critical habitat for SONCC coho.  This coho species
typically migrates north along the coast.  While migrating individuals
may utilize the coastal habitat off of the Siuslaw River for migratory
purposes, they are likely to be further offshore than the proposed ocean
disposal sites.

The Southern Distinct Population Segment (DPS) of green sturgeon
(Acipenser medirostris) is a federally threatened species.  Critical
habitat has been designated for the species (74 FR 52300, 9 October
2009).  Green sturgeon that spawn to the north, primarily in the Klamath
and Rogue rivers, constitute the Northern DPS, which is not federally
listed.  These two DPSs for sturgeon were established because they were
genetically distinct.  Southern DPS green sturgeon may be observed in
the vicinity of the proposed ocean disposal sites offshore of the
Siuslaw River as they migrate to northern estuaries during summer and
early fall.

The Southern DPS of Pacific Eulachon was proposed threatened in March
2009.  Eulachon (commonly called smelt, candlefish, or hooligan) are a
small, anadromous fish from the eastern Pacific Ocean.  Eulachon
typically spend 3-5 years in saltwater before returning to freshwater to
spawn from late winter through mid spring.  Eulachon occur in nearshore
ocean waters and to 1,000 feet in depth, except for the brief spawning
runs into their natal (birth) streams.  In the continental United
States, most eulachon originate in the Columbia River Basin.  Other
areas where eulachon have been documented include the Sacramento River,
Russian River, Humboldt Bay and several nearby smaller coastal rivers,
and the Klamath River in California; the Rogue and Umpqua rivers in
Oregon; and infrequently in coastal rivers and tributaries to Puget
Sound, Washington.  The NMFS Status Review for Eulachon concluded that
eulachon were thought to occur in “rare” relative abundance in the
Siuslaw River (NMFS 2008).  Although eulachon migrate along the coast,
little is known about eulachon use of the nearshore and marine habitat.

Federally listed avian species that may be present in the Siuslaw
offshore area include the marbled murrelet, brown pelican, and
short-tailed albatross.  Threatened marbled murrelets are observed in
small flocks or as individuals in the ocean throughout the year. 
Endangered brown pelicans are abundant from June to September along the
coast and in the lower reach of the Siuslaw River estuary.  The
endangered short-tailed albatross may forage in open ocean areas off the
coast, however the normal range for this species is Alaska and sightings
are rare along the Oregon coast.

Two shoreline areas in Lane County support breeding and wintering
western snowy plovers (Charadrius alexandrinus nivosus), a federally
threatened species (USFWS 2007).  These shoreline areas are Heceta Head
to the Siuslaw River, and the Siuslaw River to the Siltcoos River. 
These shoreline areas fall outside the limits of the Siuslaw River
project and would not be affected by ocean disposal activities.

The blue, fin, sei, sperm, humpback, and southern resident killer whales
are all federally endangered and have been observed as migrants off the
coast in waters typically farther from shore than within the proposed
Siuslaw ocean disposal sites.  Threatened Steller sea lions are
year-long residents and forage at the river mouth and nearshore areas
along the coast.  The proposed ocean disposal sites are not located in
or near designated critical habitat for the Steller sea lion.

Socio-Economic Resources

The City of Florence is bordered by both the Pacific Ocean and Siuslaw
River.  The 2000 Census reported that Florence had a total population of
7,263 people, a 40.7% increase from the 1990 Census.  Based on the 2000
Census, highest employment in Florence was in educational, health and
social services (22.9%), followed by accommodation and food services
(16.6%), retail trade (16.1%), government (12.1%), and agriculture,
forestry, fishing, and hunting (3.8%).

Cultural Resources

Appendix D provides detailed information concerning cultural resources
offshore of the mouth of the Siuslaw River.  Prehistoric cultural
resources are unlikely to be found within the Siuslaw River offshore
area.  Shipwrecks are the most probable cultural resources to be
expected within the offshore area.  A review of the historical records
indicates several recorded shipwrecks in the Siuslaw offshore area (see
Appendix D).  Side-scan sonar surveys were conducted in the area, and no
shipwrecks or other historic remnants were detected.  Based on the
studies and research in Appendix D, there are no known shipwrecks
offshore of the mouth of the Siuslaw River.

Recreational Uses

Recreational resources in the area of the proposed Siuslaw River ocean
disposal sites are described in Appendix E.  Although the Siuslaw River
area receives recreational use year-round, the most popular months are
from May through October.  Fishing in the area is particularly popular
because of the excellent fishing opportunities in the Siuslaw River and
nearby freshwater lakes.  Other recreational activities include camping,
picnicking, beachcombing, and sightseeing.

The Siuslaw River marks the northern boundary of the Oregon Dunes
National Recreation Area.  This portion of the recreation area contains
no developed facilities other than a paved road that parallels the
shoreline and provides access to the beach and South Jetty area.  During
the summer, beachcombing and sightseeing are the most popular
activities.  The Siuslaw jetty fishery is popular and accounts for a
relatively high number of angler use days.  The jetties are among the
best in the state for catching surf perch.  The most popular season is
May through September.  Scuba diving is another activity which occurs on
the outside of both jetties.  The main attraction for divers is the
opportunity for spear fishing.

A locally important salmon fishery exists offshore of the Siuslaw River.
 Even though the offshore salmon fishing can be productive, a rough bar
has periodically limited this opportunity for most small pleasure craft.
 Salmon fishing is most popular from May through September when ocean
conditions are more predictable and salmon are feeding in the nearshore
area prior to the fall spawning runs.

A smooth bottom offshore of the Siuslaw River has limited the
establishment of any substantial bottom fish populations.  One exception
is a small area located just off the mouth which has proven productive
for flounder fishing.  The lack of good bottom fishing opportunities and
the relatively short salmon fishing season have limited the number of
charter boats in the area.

Commercial Uses

The Siuslaw River offshore area supports a moderate commercial fishery
primarily for salmon, groundfish, and Dungeness crabs.  Clams are
commercially harvested in the estuary.  The fishing and tourist
industries are a primary source of income to the local economy.  No
significant mineral or petroleum deposits are known to exist in the
vicinity of the proposed Siuslaw ocean disposal sites.

ANALYSIS OF ALTERNATIVES

A Section 102 site designation allows for long-term sustainable use with
no specified time limit on the life of the site. Specific regulatory
criteria and factors per the MPRSA are analyzed later in this document. 

The EPA and the USACE considered several alternatives for disposal of
dredged material generated from the Siuslaw River navigation project and
other projects with authorized users.  Those alternatives included no
action, upland disposal, and estuarine disposal.  Alternatives
considered for ocean disposal included disposal off the continental
shelf, continued use of the existing ocean disposal sites, and/or
designation of new sites.  Although other users may require dredged
material disposal options, the USACE navigation project is the largest
and most regular source of dredged material in the vicinity.  Since
other potential, but smaller, users of the site would likely face many
of the same constraints as the USACE in the disposal of dredged
material, the discussion of alternatives focuses primarily on USACE
navigational dredging. 

No Action Alternative

Under the no action alternative, EPA would refrain from formal
designation of any ODMDS for the placement of dredged material by the
USACE or other authorized persons or entities.  If EPA did not designate
site(s), the USACE has the authority to select alternate sites under
MPRSA Section 103.  The substantive requirements for information and
evaluation of a Section 103 site are similar to those of an EPA formal
designation under Section 102, and site designation under Section 103
requires EPA concurrence.  In addition, the use of a Section 103 site is
limited to 5 years with one possible 5-year extension.  The present
sites being used at Siuslaw River are Section 103 sites. At the end of
the 2009 dredging season, both present sites will have reached the
10-year use restriction and will no longer be available for use.  The
no-action alternative would not meet the project purpose, which is to
provide dredged material disposal capacity for long-term use by the
USACE for the federally authorized Siuslaw River navigation project and
disposal capacity for other potential users.  Therefore, the no action
alternative was judged by both the USACE and EPA to be unacceptable and
was dropped from further consideration.

Upland Disposal Alternative

Hopper dredges are self-propelled, seagoing vessels and are the only
equipment that can be used to dredge the navigation channel because they
can move quickly to minimize interference with navigation traffic and
can adjust to rapidly changing weather and sea conditions.  Because
hopper dredges stockpile dredged material on-board and are designed to
bottom dump that material, they are most efficiently utilized in
conjunction with an in-water disposal area.  Rehandling of material,
moving it from the hopper dredge to another location for disposal,
introduces an additional cost and logistical component to the process. 
To dispose of material from a hopper dredge to a land-based disposal
site would necessitate dredging an in-water sump in the estuary, bottom
dumping the dredged material from the hopper dredge into the in-water
sump, and then pumping the material ashore with a pipeline suction
dredge.  Aside from increased costs, this approach would have additional
adverse environmental impacts associated with the dredging of an
in-water estuarine site to be used as the sump.  Estuarine sites are
both highly valued and limited (see below for additional discussion). 
In addition, a significant adverse impact of upland disposal is that
naturally occurring sediments would be removed from the littoral system.
 For the purposes of this analysis, regular upland disposal of Siuslaw
River entrance material is not considered feasible due to the economic
and environmental effects resulting from nearshore rehandling of dredged
material.

Estuarine Disposal Alternative

Estuarine habitat is limited and environmentally sensitive.  Placement
of dredged material in estuarine areas is generally only environmentally
acceptable for specific beneficial uses, such as in areas where
substrate is eroding and the dredged material would be suitable (e.g.,
fine-grained and clean) to supplement existing substrate.  In general,
disposal of dredged material in estuaries would result in greater
adverse environmental impacts than disposal in the ocean due to both the
limited abundance and high productivity of estuaries relative to
nearshore oceanic habitats.  Disposal of material into the estuary would
also increase the risk of the material eroding and reshoaling in the
channel, potentially increasing dredging frequency and/or volumes.

There are operational constraints to estuarine disposal as well.  Due to
the narrow and shallow confines of the Siuslaw River estuary, no
suitable estuarine disposal areas were identified that could be accessed
by a hopper dredge and could accept the volume of material annually
dredged from the Siuslaw River entrance channel.

Ocean Disposal Alternatives

Ocean disposal alternatives include disposal of the material off the
continental shelf, continued use, by designation, of the existing
Section 103 ocean disposal sites, or designation of a new ocean disposal
site(s). In addition to general criteria and specific factors required
for analysis by MPRSA, at Siuslaw, EPA has site management criteria that
will be applied when managing disposal at a designated site, and that
help to inform the alternatives analysis. These include maximizing site
capacity and lifetime by maximizing the volume of material that moves
from the site into the natural nearshore littoral system; avoiding the
potential for mounding and associated safety concerns (e.g. encouraging
rapid dispersal); supporting safe and efficient site use/management and
site monitoring logistics; and avoiding adverse effects to unique
resources. 

Disposal Off the Continental Shelf

The MPRSA directs EPA to utilize, whenever feasible, locations beyond
the edge of the continental shelf (Section 102(a)(I), 33 U.S.C. §
1412(a)(I)).  This same directive is found in the regulations in the
general criteria at 40 CFR § 228.5(e).  Transporting dredged material
off the continental shelf presents potentially significant environmental
concerns.  Benthic and pelagic ecosystems near the shelf contain
important fishery resources and the effects of disposal operations on
them are not well understood.  Fine-grained sediment and rocky habitats
would be directly impacted by disposal.  These deep-water areas are
stable and generally not disturbed by wave action or sediment movement. 
Consequently, the benthic invertebrate communities in these deep,
offshore environments are adapted to very stable conditions and would
likely be less able to survive disturbance from the immediate impact of
disposal and the long-term alteration of substrate type.  Bottom
gradients can be 5% to 25% on the continental slope, making accumulated
unconsolidated sediments susceptible to slumping.  Deposited sediments
could be transported long distances both downslope, through turbidity
currents, and offshore, by near-bottom currents, potentially affecting
organisms outside of any designated site.

Disposal off the continental shelf would remove natural sediments from
the nearshore Hecata Head littoral transport system, a system that
functions with largely non-renewable quantities of sand in Oregon. 
While the loss of the present volumes of Siuslaw River dredged material
is unlikely to result in disruption of the mass balance of the littoral
system, the State of Oregon is already experiencing erosion/accretion
patterns that are adversely impacting beaches, spits, wetlands, and
other shoreline habitats. Consequently, keeping this material in the
littoral system is perceived as a benefit and helps to sustain a dynamic
equilibrium along the Oregon coast. 

An additional limiting factor in considering a location beyond the edge
of the continental shelf is logistical feasibility.  At and in the
vicinity of the Siuslaw River, potential disposal areas located off the
continental shelf would be at least 15 nautical miles offshore in water
depths of 600 feet or greater.  This distance is well beyond the
reasonable haul distance of hopper dredges working the Siuslaw River
project, which is discussed in greater detail in the discussion of the
Zone of Siting Feasibility (ZSF).  In addition, the feasibility of
monitoring a site located off the continental shelf is questionable,
based on safety, cost, and time constraints correlated with increased
distance from shore.

Given potential uncertain environmental concerns, coupled with the
cost/logistical issues of both disposal and monitoring, disposal off the
continental shelf is not a feasible alternative.  Substantial additional
investigation would be required to determine the scope of the possible
environmental impacts of this alternative.  Such an investigation is not
warranted unless there are no suitable sites closer to shore.

Continued Use of Existing Sites

The two existing 103-selected Siuslaw ocean disposal sites (B and C)
have been used for disposal of dredged material since 1997 (see Table 1
and Figure 2).  Based on placement of dredged material between 1997 and
2009 at the sites prior to designation, approximately 800,000 cy total
have been placed, for a 13-year average annual loading volume of about
60,000 cy/year.  Annual bathymetric surveys have shown the potential for
mounding at the two previously utilized Section 103 Sites B and C. 
Disposal restrictions, until lifted in 2008, were placed on the
southeast corner of Site B which overlapped the much smaller original
1977 Interim Site A.  Since there has been a history of mounding at all
of the previously utilized Siuslaw ocean disposal sites, continued use
of existing sites is not considered a viable alternative. 

Designation of New ODMDS

New ODMDS could be evaluated for designation in location(s) that
incorporate the existing historical disposal sites, or a new disposal
site could be designated in an entirely new location. EPA and the USACE
prefer to continue use of the two existing historical sites because
there is a clear regulatory preference for the designation of previously
used sites (40 CFR 228.5(e)), and with expansion and adaptive
management, they are anticipated to meet the goals for designation. In
addition, EPA can utilize past monitoring and surveillance information
from these sites for designation, and maintain continuity of monitoring,
while extending the monitoring program to expansion areas.  

The EPA is proposing to increase capacity and minimize mounding by
designating both a larger North and larger South ODMDS for the Siuslaw
River.  Generally, material placed deeper than 60 feet disperses slowly,
and is therefore removed from the active littoral system.  To keep more
material in the nearshore active littoral system, EPA proposes a North
Site configuration that expands the existing 103 Site B to include the
original 1977 Interim Site (Site A), and a similar “shallow” (30’
to 60’ deep) area to the north of Site A, away from the river mouth.
EPA proposes to utilize the shallower portions of the North site to the
maximum extent possible in order to keep material in the active littoral
zone, and to promote dispersal of material from the site. The EPA
acknowledges that previous studies showed the potential for material
disposed within the southeastern portions of Site A to re-enter the
channel.  However, by allowing for adaptive management at an expanded
North site, EPA and the USACE do not expect measurable volumes of
dredged material to migrate back into the channel from the proposed
North Site.  In addition, the proposed South site’s southern boundary
was moved to the south, away from the river mouth, doubling the size of
the site.  Continued management and monitoring of the new Section 102
North and South sites will take place in accordance with a Site
Monitoring and Management Plan (see Appendix F).

ANALYSIS OF OCEAN DUMPING SITE DESIGNATION PROCESS AND ENVIRONMENTAL
EFFECTS

Overview

Formal designation of ocean dumping sites is the responsibility of EPA
as stated in the MPRSA.  The process for site designation is found in
the ocean dumping regulations at 40 CFR Part 228.  The process followed
by EPA, Region 10, and the USACE for the proposed Siuslaw River ocean
disposal sites generally follows the site designation procedures
developed by a joint task force of EPA and USACE personnel titled,
General Approach to Designation Studies for Ocean Dredged Material
Disposal Sites (EPA/USACE 1984).

The procedures utilize a hierarchical framework that initially
establishes the broadest economically and operationally feasible area of
consideration for site location.  A step-by-step sequence of activities
is then conducted to eliminate critical and/or unsuitable subareas. 
Further evaluation of alternative sites (candidate sites) within this
area entails various levels of assessment as suggested by the
sensitivity and value of critical resources or uses at risk, and
potential for unreasonable adverse impact presented by the dredged
material to be disposed.  The site designation criteria at 40 CFR §§
228.5 to 228.6 are applied to the information assembled through this
process, and a final site or sites are selected and proposed for formal
designation.

The MPRSA (33 U.S.C. 1401 to 1445) tasks EPA and the USACE with the
joint obligation to ensure that ocean disposal will not “unreasonably
degrade or endanger human health, welfare, or amenities, or the marine
environment, ecological systems, or economic potentialities.”  The
EPA’s site criteria and joint EPA/USACE guidance are intended to
result in the designation of an environmentally acceptable site,
oriented toward avoidance of unreasonable degradation or endangerment of
human health, welfare, or amenities, or the marine environment,
ecological systems, or economic potentialities, which is operationally
efficient.  

Defining a Zone of Siting Feasibility

At the outset, and pursuant to jointly developed guidance titled General
Approach to Designation Studies for Ocean Dredged Materials Disposal
Sites (EPA/USACE 1984), a geographic area of consideration referred to
as a Zone of Siting Feasibility (ZSF) is a first step towards
designating a site.  According to the guidance, a reasonable distance of
haul from the dredging site to the disposal site is the determining
factor in establishing the ZSF, and will be affected by available
dredging equipment, energy use constraints, costs, and safety
considerations.  The initial ZSF, once established, is evaluated
according to the statutory and regulatory criteria under the MPRSA. 
Each of the criteria is overlain on the preliminary ZSF in sequence to
eliminate unsuitable areas and determine the location and overall
suitability of remaining sites, if any, within the ZSF that could be
designated for the disposal of dredged material.  If, based on that
evaluation, a suitable site is not located within the initial ZSF, then
the area of consideration must be expanded in order to ensure that a
disposal site can be designated that will not unreasonably degrade or
endanger human health, welfare, amenities, the marine environment, or
ecological systems.

Although an ODMDS may be proposed for use and potentially utilized by
any person or entity, the primary anticipated user for the currently
proposed Siuslaw ODMDS is the Corps, who is expected to use the site
annually for disposal of dredged material from the Siuslaw River
navigation project.  No other potential users of the proposed Siuslaw
ODMDS have been identified at this time.  Therefore, the discussion of
the ZSF below is based solely on the Corps’ anticipated disposal
activities.

On the West Coast, weather and ocean conditions are major considerations
and act as significant limiting factors when assessing the reasonable
distance of haul.  Rough seas and adverse weather conditions are the
norm from October through May on the West Coast.  These conditions act
to limit ocean disposal of dredged material to a narrow window where it
is generally safe to work from roughly the end of May to no later than
mid-October, with a high probability of down time due to adverse weather
at either end of that period.

The availability of dredging equipment is also a constraint that must be
considered in the determination of a ZSF for a proposed ocean disposal
site, but particularly so for sites on the West Coast of the United
States.  For most of the designated sites in Oregon, the USACE is the
primary user and must confront equipment availability issues.  The USACE
evaluates the availability of Government or contract equipment annually
and allocates the use of government dredges for the nation.  Hopper
dredges are mobile, can work in sea swell conditions up to 10 feet, and
are self-propelled.  Therefore, they are generally the only feasible
equipment for dredging most ocean entrance channel/bar situations.

Hopper dredge availability on the West Coast has been limited.  Many
hopper dredges working in the U.S. are often committed to other work on
the Atlantic and Gulf of Mexico coasts and are not available to be used
elsewhere, except perhaps on an emergency basis.  As a result, there are
typically three hopper dredges working on the West Coast that can be
used safely at the Siuslaw River. These dredges must also maintain other
projects in Oregon, Washington, California, and occasionally Hawaii and
Alaska.

Siuslaw River Zone of Siting Feasibility

The 8-year average (2002-2009) for dredging at the Corps’ Siuslaw
River navigation project is 57,495 cy.  The amount of time necessary to
maintain a coastal project (exclusive of weather downtime) is a function
of dredging a hopper full of material (loading), then transporting that
material to, and placing it at, the disposal site(s).  This is called
“cycle time” and the cycle time can be different for each dredge. 
Loading time is essentially fixed based on the characteristics of the
sediments being dredged, the dredge itself (i.e., pumps, size of hopper,
drag arms, etc) and the dredging site conditions.  The time to discharge
material also is basically fixed for a given dredge and the type of
material, but may vary slightly depending on the disposal methodology
outlined in the Site Management and Monitoring Plan (SMMP).  The SMMP
will direct disposal activities in such a manner to minimize mounding or
other environmental effects at the ODMDS.  Transport time depends
primarily on the haul distance to the disposal site as the speed of
different hopper dredges, when full, are similar.  Thus, the critical
element for new construction or maintenance dredging is the haul
distance between the dredging site and the disposal site from both a
time and cost perspective.  A significant haul distance will affect the
ability to construct or maintain the individual project and very
probably would have repercussions on the Corps’ ability to maintain
other West Coast projects.

Under current and foreseeable conditions at the project, the estimated
volume of material to be removed annually is expected to remain near the
current average of 57,495 cy. Based on workload, available funding, and
other constraints, the Government-owned hopper dredge Yaquina is
typically expected to be available 6.92 days (according to latest 8-year
average) at the Siuslaw River navigation project, or a contract dredge
is expected to be available for a similar length of time.  This
translates into an 8,309 cy per day average production requirement.  The
rated capacity for the Yaquina is 1,042 cy and the average load for the
Siuslaw project is 1,002 cy/load.  Pump time typically is around 65
minutes for the Siuslaw project.  Depending on the SMMP, environmental
conditions, and characteristics of the dredged material, dump time could
vary from 2 to 6 minutes.  The dredge typically works 24 hours per day
except for Tuesdays when the crew change occurs.  The ZSF can be
calculated as follows:

Assume 8.29 loads per day (8,309 cy/day ( 1,002 cy/load = 8.29
loads/day)

Pump time (1.085 hr) + Dump time (0.095 hr) = 1.18 hr/load x 8.29 loads
or 9.79 hr/day

24 hr/day - 9.79 hr/day = 14.21 hr/day for transit to and from the
disposal site

14.21 hr/day ( 8.29 loads/day = 1.71 hour transit time for one round
trip

1.71 ( 2 = 0.855 hr transit one way

0.855 x 6 kts (vessel speed) = 5.14 nautical miles

Thus, the outer limit of the ZSF for the Siuslaw ODMDS, as limited by
the capacity of the available dredging plant, average annual dredging
quantity, and limited dredging time period, is 5.14 nautical miles from
the Siuslaw River navigation project.  This is the area within which
potential sites will initially be evaluated according to the MPRSA
statutory and regulatory criteria.

Regulatory Criteria for Ocean Disposal Site Selection

The EPA evaluated the four general (40 CFR 228.5) and 11 specific (40
CFR 228.6) regulatory criteria for site designation in reviewing the
currently proposed Siuslaw River North and South ODMDS.  A conflict
matrix format is utilized in Table 2 to simplify and consolidate scoring
for the general and specific site criteria review process.  Each area of
consideration on the conflict matrix addresses at least one general or
specific criterion.  A legend defining the matrix categories follows the
table.

Application of Four General Criteria (40 CFR 228.5)

Minimize Interference with Other Activities (a.).  The first of the four
general criteria requires that a determination be made as to whether the
proposed site or its use will minimize interference with other uses of
the marine environment.  This determination was made by overlaying
individual uses with the resources presented in the Siuslaw Ocean
Dredged Material Disposal Site Evaluation (USACE 1992) and the more
recent appendices prepared for this evaluation.  The report presented
the overlays on a base map giving bathymetry and location of the
previous ocean disposal sites in the ZSF.  The more interactions between
various uses and limited resources exist, the more critical the area. 
The overlay process was used to minimize interference with other uses of
the ocean.  The selection of features to use for this determination was
dependent on whether the resource was considered limited.



Table   SEQ Table \* ARABIC  2 .  Proposed Siuslaw North and South ODMDS
Conflict Matrix

AREA OF

CONSIDERATION 1/	CONFLICT 2/	POTENTIAL CONFLICT	NO CONFLICT	BENEFICIAL
USE	COMMENTS	RELEVANT SPECIFIC FACTORS

11 Specific Factors 3/

(40 CFR 228.6)	RELEVANT GENERAL

CRITERIA

4 General Criteria 4/

(40 CFR 228.5)

1.  Unusual Topography/Unique Bottom Features

	X

	1, 6, 8, 11	a

2.  Physical Sediment Compatibility

	X

	3, 4, 9	b, d

3.  Chemical Sediment Compatibility

	X

Periodic monitoring conducted	3, 4, 7, 9	a, b, d

4.  Influence of Past Disposal

X

	Mounding due to past disposal	5, 7, 9, 10	a, b, d

5.  Living Resources of Limited Distribution

	X

	2, 3, 6, 8, 11	a, b, d

6.  Commercial Fisheries

X

	Salmon, pelagic fish, crabs	2, 8	a, b

7.  Recreational Fisheries

X

	Salmon, pelagic fish	2, 8	a, b

8.  Breeding/Spawning Areas

	X

	2, 8	a, b

9.  Nursery Areas

X

	Juvenile flatfish and crabs.	2, 8	a, b

10.  Feeding Areas

X

	Juvenile/adult salmonids, marine mammals, pelagic birds	2, 8	a, b

11.  Migration Routes

X

	Marine mammals, salmonids, pelagic and shore birds	2, 8	a, b

12.  Critical Habitat of Threatened or Endangered Species

	X

No critical habitat present	2, 8	a, b

13.  Spatial Distribution of Benthos

	X

	2, 8, 10	a, b

14.  Marine Mammals

X

	Potential impact to resident and migratory species	2, 8	a, b

15.  Mineral Deposits

	X

	1, 8	a, b, 

16.  Navigation Hazard

X

	Navigation of small boats around the dredge	1, 8	a, b, d

17.  Other Uses of Ocean

(cables, pipelines, etc)

	X

	8	a, b, d

18.  Degraded Areas

	X

	4, 6, 7	a, b, d

19.  Water Column Chemical/Physical Characteristics

	X

	4, 6, 9	a, b, d

20.  Recreational Uses

X

	Inconvenience to recreational boats	2, 8, 11	a, b, d

21.  Cultural/Historic Sites

	X

No shipwrecks identified	11	b

22.  Physical Oceanography - Waves/Circulation

	X

	1, 3, 6, 7	a, b, d

23.  Direction of Transport/Potential for Settlement

	X

	1, 3, 6, 7	a, b, d

24.  Monitoring

	X

	5	a, d

25.  Shape/Size of Site

	X

	1, 4, 7	d

26.  Size of Buffer Zone

	X

	2, 3, 4, 7, 11	b, d

27.  Potential for Cumulative Effects

	X

	4, 7	d

Conflict Matrix Tables Legend

1/  Definition of “Areas of Consideration”

1.  Unusual Topography/Unique Bottom Features:  Would placement of
material in this candidate site affect physical bottom feature that is
unique within the local or regional area?

2.  Physical Sediment Compatibility:  Does the candidate site have
similar sediment characteristics to anticipated dredged material?

3.  Chemical Sediment Compatibility:  Does the candidate site have
similar chemical characteristics to anticipated dredged material?

4.  Influence of Past Disposal:  Would placement of material in this
candidate site be affected by previous disposal of dredge material?

5.  Living Resources of Limited Distribution:  Would placement of
material in this candidate site affect any living resources that do not
have a coast-wide distribution?

6.  Commercial Fisheries:  Would placement of material in this candidate
site affect any commercial fishing activity (resource impacts are
covered in 8-11)?

7.  Recreational Fisheries:  Would placement of material in this
candidate site affect any recreational fishing activity (resource
impacts are covered in 8-11)?

8.  Breeding/Spawning Areas:  Would placement of material in this
candidate site affect breeding and spawning areas of any species?

9.  Nursery Areas:  Would placement of material in this candidate site
affect nursery areas of any species?

10.  Feeding Areas:  Would placement of material in this candidate site
affect feeding areas of any species?

11.  Migration Routes:  Would placement of material in this candidate
site affect migration routes of species?

12.  Critical Habitat of Threatened or Endangered Species:  Would
placement of material in this candidate site affect critical habitat of
threatened or endangered species?

13.  Spatial Distribution of Benthos:  Would placement of material in
this candidate site change the benthic invertebrate community structure
(e.g., fine-gain species to coarse-grain species, etc)?

14.  Marine Mammals:  Would placement of material in this candidate site
affect marine mammals or their habitat (e.g., gray whale feeding areas
etc)?

15.  Mineral Deposits:  Would any known mineral deposits be affected by
the placement of material?

16.  Navigation Hazard:  Would the placement of material create a
navigation hazard?

17.  Other Uses of Ocean:  Would placement of material impact other uses
of the ocean not addressed elsewhere, such as cables, pipelines, tow
boat lanes, and pilot transfer points?

18.  Degraded Areas:  Would disposal in this candidate site continue to
affect or improve the degraded area?

19.  Water Column Chemical/Physical Characteristics:  Would placement of
material in this candidate site affect water column chemical/physical
characteristics?

20.  Recreational Uses:  Would placement of material affect recreational
uses?

21.  Cultural/Historic Sites:  Would placement of material in this
candidate site impact or protect a cultural/historic site?

22.  Physical Oceanography, Waves/Circulation:  Would placement of
material affect wave/circulation patterns?

23.  Direction of Transport/Potential for Settlement:  Would placement
of material affect direction of sediment transport and/or potential for
settlement?

24.  Monitoring:  Would use of this candidate site affect either
on-going monitoring or the ability to monitor using conventional
methods?  Monitoring typically would include periodic hydrographic
surveys and could include sediment sampling or biological data
collection.

25.  Shape/Size of Candidate Site:  Is the candidate site suitable for
the operation and maneuverability 

of a dredge?

Is it oriented so the dredge can place material while heading into the
waves?

Is the depth of water sufficient to open the hopper doors/dump scow?

Can the dredge operate safely?

Is the size of the candidate site large enough for long-term use?

26.  Size of Buffer Zone:  Is the candidates site a sufficient distance
from important resources or features to protect them from any affect of
disposal?

27.  Potential for Cumulative Effects:  Would placement of material
contribute to cumulative affects from other activities?

Conflict Matrix Tables Legend (continued)

2/  Definition of Degrees of Conflict

Conflict:  There will definitely be an adverse impact on the resource or
the use.

Potential Conflict:  There is a possibility of an adverse impact;
however, extent and significance are unknown.

No Conflict:  There will definitely not be an adverse impact on the
resource or the use.

Beneficial Use:  There will be a positive impact on the resource or the
use.

3/  Eleven Specific Factors for Ocean Disposal Site Selection

1.  Geographical position, depth of water, bottom topography, and
distance from coast.

2.  Location in relation to breeding, spawning, nursery, feeding, or
passage areas of living resources in adult or juvenile phases.

3.  Location in relation to beaches or other amenity areas.

4.  Types and quantities of waste proposed to be disposed and proposed
methods of release, including methods of packaging the waste, if any.

5.  Feasibility of surveillance and monitoring.

6.  Dispersal, horizontal transport, and vertical mixing characteristics
of the area, including prevailing current 1 velocity, if any.

7.  Existence and effects of present or previous discharges and dumping
in the area (including cumulative effects).

8.  Interference with shipping, fishing, recreation, mineral extraction,
desalination, shellfish culture, areas of special scientific importance
and other legitimate uses of the ocean.

9.  Existing water quality and ecology of the site, as determined by
available data or by trend assessment or baseline surveys.

10.  Potential for the development or recruitment of nuisance species
within the disposal site.

11.  Existence at or in close proximity to the site of any significant
natural or cultural features of historical importance.

4/  Four General Criteria for the Selection of Ocean Disposal Sites

a.  The dumping of material into the ocean will be permitted only at
sites or in areas selected to minimize the interference of disposal
activities with other activities in the marine environment, particularly
avoiding areas of existing fisheries or shell fisheries, and regions of
heavy commercial or recreational navigation.

b.  Locations and boundaries of disposal sites will be chosen so that
temporary perturbations in water quality or other environmental
conditions during initial mixing caused by disposal operations anywhere
within the site can be expected to be reduced to normal ambient seawater
levels or to undetectable contaminant concentrations or effects before
reaching any beach, shoreline, marine sanctuary, or known geographically
limited fishery or shell fishery.

c.  Effective January 1, 2009, this paragraph, 40 CFR 228.5(c) was
removed and reserved, see 73 Fed. Reg. 74983 (December 10, 2008), and is
therefore no longer a criterion in the regulations. 

d.  The sizes of ocean disposal sites will be limited in order to
localize, for identification and control, any single immediate adverse
impact and to permit the implementation of effective monitoring and
surveillance programs to prevent adverse, long-range impacts.  The size,
configuration, and location of any disposal site will be determined as a
part of the disposal site evaluation or designation study.

e.  EPA will, whenever feasible, designate ocean dumping sites beyond
the edge of the continental shelf and other such sites that have been
historically used.

The following were selected for evaluation of resources of limited
distribution:

1.  Navigation Hazards Area/Other Recreation Areas

2.  Shellfish Areas

3.  Critical Aquatic Resources

4.  Commercial and Sport Fishing Areas

5.  Geological Features

6.  Cultural, Historically Significant Areas

Figure 4 is a composite of the above areas and shows high usage areas
within the vicinity of the Siuslaw ocean disposal sites.  The denser the
pattern overlap, the more interactions between various limited resources
exist, thus the more critical the overlap area.

Figure   SEQ Figure \* ARABIC  4 .  Overlay Evaluation of Individual
Resources

As Figure 4 shows, the adjusted sites are within minimal conflict areas
in the ZSF.  Disposal operations occur generally between June 1 and
October 31 of each year.  While this represents a temporal overlap,
communications with USACE personnel indicate no observable conflicts
between the dredging activities and the fishery.  Appendix A contains a
discussion of all potential conflicts within the ZSF with living
resources, and concludes that there are no major conflicts or
predictable future conflicts.

Minimizes Changes in Water Quality (b).  The second of the four general
criteria requires changes to ambient seawater quality levels occurring
outside the disposal sites to be within water quality criteria, and that
no detectable contaminants reach beaches, shoreline, sanctuaries, or
geographically limited fisheries or shellfisheries.  No significant
contaminant or suspended solids releases are expected with disposal of
Siuslaw sandy material (about 97% of dredged material) or disposal of
finer-grained material (about 3% of dredged material) (see Appendix C).
The proposed sites should not have any long-term impact on the water
quality, with the primary impact of disposal activities on water quality
expected to be the temporary turbidity caused by the physical movement
of sediment through the water column. There should be no water quality
perturbations moving toward a limited resource.  Bottom movement of
deposited material is discussed in Appendix B.

Interim Sites Which Do Not Meet Criteria (c).  Effective as of January
1, 2009, this paragraph, 40 CFR 228.5(c) was removed and reserved. See
73 Fed. Reg. 74983 (December 10, 2008), and is therefore no longer a
criterion in the regulations. 

Size of Sites (d).  The third general criterion requires that the size,
configuration, and location of the site(s) be evaluated as part of the
study, and that the size be limited. 

Since 1977 specific dredged material disposal sites have been used off
the mouth of the Siuslaw River. More than thirty-years of monitoring at
Siuslaw and other Oregon ODMDS have shown that original 1977 Interim
Site configurations were too limited in size. Potential mounding limited
long-term site capacity, and since there has been a history of mounding
at the smaller previously utilized sites, it is clear that new
designated sites should be larger to increase capacity and enhance
dispersal.  

The USACE 1992 Siuslaw Ocean Dredged Material Disposal Site Evaluation
report identified two ODMDSs north and south of the entrance. These
sites have been used under the Corps Section 103 site selection
authority since 1997. This tripled the area available for dredged
material placement compared to the relatively small 1977 Interim Site.
Based upon annual bathymetric monitoring of the Section 103 sites from
1981 to 2009 (See Appendix B figures B-4 through B-8), EPA proposes to
ensure long-term disposal capacity by enlarging the designated sites --
doubling the South Site and expanding the North Site into shallower
water.  Two sites are again being proposed, to ensure site managers can
be responsive to the specifics of each dredging season based on dredge
schedules and recorded seasonal sediment transport patterns north and
south along the Oregon coast. 

The proposed sites are located within the generally homogeneous sandy
habitat off the mouth of the Siuslaw River, within a reasonable haul
distance from dredging areas and generally removed from other use
conflicts. They encompass previously used and monitored sites, so past
monitoring data may be used to manage the sites. The proposed sites now
incorporate shallow and deep water areas. Use of the shallower portion
of the North Site will facilitate increased sediment transport thereby
increasing long-term site capacity. Preferential utilization of the
shallow portions of the North Site also meets the management goal of
keeping material in the littoral system. However, as seen in the 1977
Interim Site, mounding could occur if too much material is placed too
quickly in shallow water. The designation of multiple sites with deeper
areas within the sites, allows site managers to be responsive to annual
and long-term sediment transport patterns. 

The proposed sites are oriented for safe and optimal on-site dredge
operations. Oriented with their long axis toward the west and northwest,
the sites allow hopper dredges leaving the Siuslaw to head perpendicular
to the dominant wave direction while disposing of dredged material. 

Finally, in addition to formal site selection criteria and factors, the
size, configuration and locations of the proposed sites meet other
selection and management considerations important to EPA, including 
maximized capacity of the sites (since a Section 102 site designation is
not limited to a predetermined number of years), minimized potential for
mounding and associated safety concerns, maximized volume of material
remaining in the littoral system, and avoidance of effects to unique
resources.  

Sites Off the Continental Shelf or Other Historically Used Sites (e). 
Any potential disposal sites off the continental shelf in the area of
the Siuslaw River would be at least 40 nautical miles offshore.  By
contrast, the Siuslaw ZSF extends a maximum of only 5.14 nautical miles
from shore.  The Siuslaw navigation project could not be economically
maintained using current dredging technology and availability if a site
off the continental shelf was used.  In addition, use of a site off the
continental shelf would result in as loss of sediments from the
nearshore littoral transport system, which could cause detrimental
bottom or shoreline changes in the ZSF.  Further, very little is known
of the ecology of benthic communities on the continental slope, and
disposal in this area could cause impacts of unknown severity. Finally,
relative monitoring and surveillance logistics would be more costly and
difficult at a site located off the continental shelf. For these
reasons, designation of an ODMDS off the continental shelf is not
recommended.  The proposed sites encompass sites that have been
historically used, meeting the second directive of this criterion.

Application of Eleven Specific Factors (40 CFR 228.6)

Geographical Position, Depth of Water, Bottom Topography, and Distance
from the Coast (1).  The proposed North and South ODMDS are
approximately 1 mile offshore from the entrance to the Siuslaw River
(see Figure 1).  Appendix B contains a discussion of the bottom
topography of the proposed sites.  The two designated sites would be
used for disposal of dredged material from the Siuslaw River navigation
project and other permitted projects.

The proposed North ODMDS is 4,800 feet by 2,000 feet with an average
depth of 90 feet (depth ranges from approximately 30-115 feet), and has
the following coordinates (NAD 83):

44o 01’ 31.03”N, 124o 10’ 12.92”W

44o 01’ 49.39”N, 124o 10’ 02.85”W

44o 01’ 31.97”N, 124o 09’ 01.86”W

44o 01’ 13.45”N, 124o 09’ 11.41”W

The proposed South ODMDS is 3,000 feet by 2,000 feet with an average
depth of 100 feet (depth ranges from approximately 80-125 feet), and has
the following coordinates (NAD 83):

44o 00’ 46.72”N, 124o 10’ 26.55”W

44o 01’ 06.41”N, 124o 10’ 24.45”W

44o 01’ 04.12”N, 124o 09’ 43.52”W

44o 00’ 44.45”N, 124o 09’ 45.63”W

Based upon consideration of the location, depth of water, bottom
topography, and distance from the coast, the proposed Siuslaw ocean
disposal sites are expected to be suitable for the disposal of dredged
material when the material is placed in accordance with the SMMP.

Location in Relation to Breeding, Spawning, Nursery, Feeding, or Passage
Areas of Living Resources in Adult or Juvenile Phases (2).  Aquatic
resources of the oceanic region off the mouth of the Siuslaw River are
described in detail in Appendix A.  In addition, EPA evaluated possible
impacts to species and critical habitat listed under the Endangered
Species Act in a Biological Assessment (EPA 2009).  The proposed ocean
disposal sites are located in the nearshore area and many nearshore
pelagic organisms are found in the water column over the sites.  These
include zooplankton (copepods, euphausiids, pteropods, and chaetognaths)
and meroplankton (fish, crab, and other invertebrate larvae).  These
organisms generally display seasonal changes in abundance.  Since they
are present in the oceanic region off of most of the Pacific Coast,
those populations directly off the Siuslaw River are small compared to
the overall coastal populations.  Based on evidence from previous
zooplankton and larval fish studies, it appears that there will be no
impacts to organisms in the water column (Sullivan and Hancock 1977). 

Benthic samples are discussed in detail in Appendix A.  Based on the
analysis of benthic samples collected from the area of the proposed
Siuslaw ocean disposal sites, the sites contain benthic fauna common to
nearshore, sandy, wave-influenced regions that exist along much of the
Pacific Coast in Oregon and Washington.

Sediment in and near the proposed Siuslaw ocean disposal sites consists
of well-sorted, fine sands typical of Pacific Northwest coastal areas
(Appendix C).  The infaunal community of the Siuslaw study area is
dominated by gammarid amphipods and polychaete worms.  The benthos in
the area is typical of the communities found near other ocean disposal
sites along the Oregon Coast, such as Coos Bay areas E and F, the
Siuslaw River, and the Chetco River (Hancock et al., 1981; USACE 1985,
1988a, 1988b, 1990).  This benthic community, largely dominated by very
mobile organisms, provides an important link in the marine food web. 
These organisms serve as a direct food source for other benthic
organisms and demersal fish.  They also play an active role in the
breakdown of organic debris and the tube-building species help stabilize
the marine sediments.  Many of the benthic species in the area are able
to survive in this dynamic environment since they are either very mobile
or are able to react both to natural or human perturbations.  They can
readily recolonize disturbed areas.

The Siuslaw nearshore area supports a variety of pelagic and demersal
fish species and shellfish.  Many of these species have a reproductive
strategy that includes releasing a large quantity of eggs so that some
individuals will survive the substantial mortality common to the species
during the larval and juvenile stages. Crabs in particular release large
number of eggs into the water column.  The larvae that hatch are
planktonic for several months before settling to the bottom of the
estuary and in the nearshore area as young crab.  During this time, they
are subjected to a variety of environmental factors that affect their
survival and have a direct affect on adult population numbers. 

Numerical modeling of the disposal process by Pearson and others (2006)
at the mouth of the Columbia River showed that predicted impact
pressure, shear stress, and mound depth were greatly reduced by
discharge in deep water (e.g., ocean disposal in 230 and 280 feet of
water).  The study found that vulnerability of crabs to compression
(vertical) forces was low and that crabs may be vulnerable to injury
from surge currents.  However, the surge currents from modeling the
deep-water scenarios were not strong enough to mobilize sediment greater
than 1 millimeter or juvenile Dungeness crabs.  Results also suggested
that Dungeness crabs were vulnerable to injury from burial through
effects on crab respiration and survival (Pearson et al., 2006). 
Previous studies showed that under burial with 10 centimeters (about 4
inches) of material, crabs were unable to recover the respiratory
pathway and switched to moving up through the sediment, a process that
occurred over 24 hours.

Vavrinec and others (2007) performed laboratory experiments to isolate
the effects on Dungeness crabs from burial by dredged material, and crab
response and injury caused by tumbling in horizontal surge currents. 
The horizontal surge current experiments showed no damage, 100 percent
survival, and the behavioral capability of crabs to recover their proper
orientation after tumbling.  The crabs either maintained their proper
orientation on the bottom and in the water column, or righted themselves
within 2 seconds after being moved by a 3.2 meter/second (about 10.5
feet/second) surge current.

The crab burial experiments (Vavrinec et al., 2007) showed that survival
from burial increased as burial depth decreased, and survival increased
as crab size increased.  Also, male crabs had a higher survival rate
than female crabs.  When restrained and not allowed an escape response,
all the adult crabs suffocated and died within 24 hours when buried in 8
centimeters of dredged material.  The observations clearly show that
maintaining the respiratory pathway is the key to surviving burial.  For
unrestrained crabs tested in large tanks with sufficient space for
escape response, survival increased substantially.  Escape response and
other adaptive behavior clearly enabled the subadult and adult crabs to
achieve almost 100 percent survival under the same burial depth that
allowed no survival at all for restrained crabs.  For unrestrained age
2+ crabs, predicted survival begins to decrease at burial depths greater
than 10 centimeters, and is less than 10 percent at burial depths
greater than 16 centimeters.  Behavioral observations and survival
results showed that subadult and adult crabs have the capability to
respond to surge currents and burial in ways that substantially reduce
exposure to stress and allow high survival.

The nearshore area off the Siuslaw River supports anadromous salmonids
including coho salmon, summer and winter steelhead, and spring and fall
Chinook salmon, as well as a variety of other pelagic and demersal fish
species.  Seals and sea lions inhabit the lower Siuslaw River and
coastal area.  The Siuslaw nearshore area and shoreline provides
important habitat for shorebirds, waterfowl, herons, and many other
species of birds.  Pelagic birds (e.g., murres, auklets, cormorants)
likely use the area for foraging.  Federally listed species that may be
present in the Siuslaw offshore area were previously discussed in the
Affected Environment, Biological Resources section of this report.

In general, the locations of the proposed ocean disposal sites do not
provide unique breeding, spawning, nursery, feeding, or passage habitat.
 It is unlikely that any of the larger organisms (fish, marine mammals,
etc.) would experience physiological effects as a consequence of
disposal because the resulting turbidity plume and physical disturbance
to the water column would likely cause them to avoid the area.  Based on
modeling completed by the USACE, water column turbidity would be
expected to dissipate within a few minutes to half hour.  Any avoidance
behavior would be limited to the duration of this physical disturbance. 
Indirect impacts could occur if disposal operations changed the value of
the habitat by burying the existing benthic community where dredged
material is deposited.  The benthic community would be expected to
re-colonize within a period of a few weeks to months after disposal,
limiting any effects to forage fish (USACE 1993).  Lastly, evaluation of
past disposal activities has not indicated that any long-term adverse
impacts to living resources have occurred.

Location in Relation to Beaches and other Amenity Areas (3).  The
proposed ocean disposal sites are at least 2,000 feet from the end of
the jetties and 3,000 feet from the nearest beach.  There are no rocks
or pinnacles in the vicinity of either site. The Siuslaw River marks the
northern boundary of the Oregon Dunes National Recreation Area. This
portion of the recreation area contains no developed facilities other
than a paved road that parallels the shoreline and provides access to
the beach and South Jetty area.  Two public recreation areas are located
to the north of the Siuslaw River. Heceta Beach Park is operated by Lane
County with beach access, picnic tables, and restrooms. Harbor Vista
Park is also operated by the county and offers 15 acres of tent and
recreation vehicle camping on a year-round basis. It is one of the few
campgrounds on the Oregon Coast with an ocean view and has restrooms,
showers, a playground and hiking trails. Beachcombing, sightseeing and
clamming are popular activities along the entire coastline. The area
within the Oregon Dunes National Recreation Area receives a greater
amount of use because of availability of public access. The proposed
designation of the Siuslaw North and South ocean disposal sites is not
expected to have any impact on the recreational uses of the adjacent
uplands areas within these recreation areas. 

Types and Quantity of Wastes Proposed to be Disposed of, and Proposed
Methods of Release, including Methods of Packing the Waste, if any (4). 
Dredged material subject to the MPRSA is not a waste.  The sites that
are designated will receive dredged materials transported by either
government or private contractor hopper dredges or dump barges.  Current
hopper dredges or dump barges available for use have capacities ranging
from 800 to 6,000 cy.  This would be the likely volume range of dredged
material deposited in any one dredging placement cycle.  The estimated
volume to be removed annually from the Siuslaw River federal navigation
project will range, but can be placed at the sites in one dredging
season by any combination of private and government dredges.  For
example, volumes from 1997 to 2009 ranged from 22,300 cy to 117,300 cy,
giving a 13-year average annual volume of about 60,000 cy. The dredges
or barges would be under power and moving during disposal.

The bulk of the dredged material to be disposed in the ocean comes from
shoals in and near the Siuslaw River entrance channel.  These shoals
consist primarily of marine sand transported into the entrance as part
of the Heceta Head littoral cell.  The material meets marine sediment
screening level guidelines for chemicals of concern per the Sediment
Evaluation Framework (SEF 2009), is far removed from known sources of
contaminants, and has been characterized under the SEF as suitable for
unconfined open-water disposal.  

The federally maintained entrance channel into the Siuslaw River is
authorized at 18 feet deep and 300 feet wide, and runs from deep water
to river mile (RM) 0.2. From there upstream to the dock at Florence (RM
5.0), the channel is maintained to 16 feet deep and 200 feet wide. A
turning basin, currently maintained by the Corps at 16 feet deep, 400
feet wide and 600 feet long, is located opposite the dock at Florence.
The channel from RM 5.0 upstream to RM 16.5 is an authorized (though not
currently maintained) federal channel, 12 feet deep and 150 feet wide.
At RM 15.8 the channel widens into a turning basin 12 feet deep, 300
feet wide and 500 feet long, also part of the federally authorized, but
not currently maintained channel. 

The channel above RM 5.0 has required very infrequent maintenance. A
pipeline dredge last cleared the shoals at RM 5.5 and 6.0 in 1982. No
dredging has been performed above that point since 1976. Siuslaw River
sediments (to RM 16.1) were last sampled in 2006. These physical and
chemical analyses indicate that the material is primarily sand, meets
marine sediment screening level guidelines for chemicals of concern per
the Sediment Evaluation Framework (SEF 2009), is far removed from known
sources of contaminants, and would be characterized under the SEF as
suitable for unconfined open-water disposal

Feasibility of Surveillance and Monitoring (5).  Monitoring and
surveillance are both feasible within the ZSF and are included as
requirements in the SMMP for these proposed sites (see Appendix F).  At
a minimum, annual bathymetric surveys will be conducted in areas that
receive dredged material.  More frequent surveys will be conducted when
necessary to ensure unacceptable mounding is not occurring that could
pose a threat to navigation safety.  If actual field monitoring of the
disposal activities is required because of a future concern for habitat
changes or limited resources, several research groups are available in
the area to perform any required work.  The proposed Siuslaw ocean
disposal sites are readily accessible.  Most surveillance and monitoring
work can be performed from small, surface research vessels at a
reasonable cost, or from the disposal vessel.

Dispersal, Horizontal Transport and Vertical Mixing Characteristics of
the Area Including Prevailing Current Direction and Velocity, if Any
(6).  The sediments dredged from the Siuslaw River entrance are
predominantly marine sands and fluvial gravels.  Although the Siuslaw
River delivers a large sediment load, the bottom contours suggest a
rapid distribution away from the river mouth.  The beaches seem to be in
equilibrium, suggesting that littoral transport is in balance.  From
bottom current records, there appears to be a net annual transport of
sediment to the north.  There is some southward sediment transport
during summer.  During summer, the current velocities are variable (see
Appendix B).  This is due to the constantly varying river outflow
combined with tidal flows to produce a highly variable influence on the
nearshore circulation.

Sediment movement in the littoral zone consists of two mechanisms
depending upon the size of the sediment.  Anything finer than sand-size
is carried in suspension in the water and is removed offshore relatively
quickly.  The almost total lack of silts and clays within the Siuslaw
ZSF attests to the efficiency of this mechanism.  Sediments sand-size or
coarser may be occasionally suspended by wave action near the bottom,
and are moved by bottom currents or directly as bedload.  Tidal, wind
and wave forces contribute to generating bottom currents, which act in
relation to the sediment grain size and water depth to produce sediment
transport.

Existence and Effects of Current and Previous Discharges and Dumping in
the Area including Cumulative Effects (7).  No cumulative effects have
been documented in the area aside from mounding, i.e. lack of material
dispersal, within the sites as currently configured. The Siuslaw North
and South ODMDS are being proposed because of mounding problems
associated with disposal at the previous 1977 Interim and Section
103-selected ocean disposal sites.  The proposed North and South sites
are located and sized to allow management of the sites – a flexible
disposal strategy implemented within larger sites to minimize mounding.
Per the SMMP, annual bathymetric monitoring will be used to track
changes in site bathymetry and will be used to evaluate potential
mounding.  The preference for disposal of material in the shallow
portions of the proposed North Site will provide the positive cumulative
effect of returning natural material to the Heceta Head littoral cell. 

Interference with Shipping, Fishing, Recreation, Mining Extraction,
Desalination, Fish and Shellfish Culture, Areas of Special Scientific
Importance, and Other Legitimate Uses of the Ocean (8).

	Shipping.  No conflicts with commercial navigation traffic have been
recorded in the long history of hopper dredging activity.  The likely
reason for this is the light commercial traffic in the Siuslaw River
channel.

	Commercial and Recreational Fishing.  Commercial and recreational
fisheries occur in and around the proposed Siuslaw ocean disposal sites
(see Appendix A).  The Siuslaw ZSF area supports a moderate commercial
fishery primarily for salmon, groundfish, and Dungeness crabs.  The
commercial fishing season generally begins in June and runs through
October, subject to established catch quotas. During this period, the
potential exists for conflicts between a dredge and fishing boats. Based
on data from the National Marine Fisheries Service (NMFS 2006) for
commercial fishing, a total of 38 vessels, all commercially registered,
delivered landings to Florence in 2000, in the following West Coast
fisheries: crab, groundfish, highly migratory species, salmon, shrimp,
and other species. Dungeness crab had the highest landing value at
$562,057, while groundfish landings were the largest by weight at 124.3
metric tons. A total of 41 commercial vessels were owned by Florence
residents in 2000, 19 of which participated in the federally-managed
groundfish fishery. 

A locally important recreational salmon fishery exists offshore of the
Siuslaw River.  Based on data from NMFS (2006), there is at least one
sport fishing charter business in Florence. There were seven sport
fishing licensing agents in Florence in 2000, when 4,907 sport fishing
licenses were sold at a value of $80,163. Even though the offshore
salmon fishing can be productive, a rough bar periodically limits this
opportunity for most small pleasure craft.  Salmon fishing is most
popular from May through September when ocean conditions are more
predictable and salmon are feeding in the nearshore area prior to the
fall spawning runs. The year 2000 recreational salmonid catch in the
ocean boat fishery was 250 Chinook salmon and 472 coho salmon.

The Siuslaw jetty fishery is also popular and accounts for a relatively
high number of angler use days.  The jetties are among the best in the
state for catching surf perch.  A smooth bottom offshore of the Siuslaw
River has limited the establishment of substantial bottom fish
populations, however the year 2000 non-salmonid catch was a total of 213
fish including greenstripe, canary, and yelloweye rockfish, and Pacific
halibut. 

	Mineral Extraction.  There are no known metallic mineral deposits
within the Siuslaw ZSF.  No exploratory oil/gas wells have been drilled
offshore near the mouth of the Siuslaw River and no development is
expected in the future.

	Desalination.  There are no desalination plants in the area of the
Siuslaw River.

	Wave Energy.  With the increased interest in alternative energy
sources, various wave energy projects have been proposed off the Oregon
Coast.  The Oregon State Governor, in a November 2007 news release to
the Oregon Fishing Industry, stated that he was asking the Federal
Energy Regulation Commission to limit the permitting of wave energy to
five to seven locations.  Wave energy projects at those locations will
involve numerous generating buoys moored offshore with transmission
lines running to shore distribution facilities.  Currently, no wave
energy projects are proposed off the Siuslaw River.

	Fish and Shellfish Culture.  There are no fish or shellfish culture
operations in the area of the proposed Siuslaw ocean disposal sites.

	Marine Reserves.  The State of Oregon has initiated efforts to
establish a network of state marine reserves as part of an overall
strategy to manage its marine waters and submerged lands.  The overall
purpose would be to protect, sustain, or restore the nearshore marine
ecosystem, its habitats, and species.  A state marine reserve, as
defined by Oregon, is an area within Oregon’s state territorial sea or
adjacent intertidal area that is protected from all extractive
activities including the removal or disturbance of living and non-living
marine resources.  Marine reserves are intended to provide lasting
protection.  Dredging and disposal are identified as disturbances and
would be banned from areas designated as marine reserves.  In 2009,
Oregon authorized two marine reserves, one at Otter Rock off Depoe Bay
and one at Redfish Rocks off Port Orford.  State agencies are to
evaluate potential reserves at Cape Falcon south of Cannon Beach,
Cascade Head near Lincoln City, and Cape Perpetua near Yachats.  State
agencies also have been directed to support a reserve proposal for the
Cape Arago-Seven Devils area, south of Coos Bay.  None of the sites
currently identified are in or near the proposed Siuslaw OSMDS, and all
coastal ocean disposal site designations will have to avoid marine
reserve areas.

	Special Scientific Importance.  There are no known transects or other
scientific study locations that would be impacted by disposal at the
proposed Siuslaw ocean disposal sites.

General Discussion of Other Legitimate Uses.  There has not been a
demonstrated conflict with any of the above listed uses at the
historically used ocean disposal sites and no use conflicts are expected
at the two proposed sites.  There is a low potential for future
conflicts given that the area of the proposed sites has no unique value,
is relatively small, and presents few potential conflicts with other
uses in the vicinity.  Since dredged material disposal sites in the
vicinity have been in use for over 30 years, EPA’s designation of the
two proposed Siuslaw ocean disposal sites would not be expected to
result in any change to the existing uses of the area, by any
individuals or groups, or any associated economic benefit of those uses.

It should also be noted that EPA is proposing to designate these ODMDS
primarily in support of the Corps’ operation and maintenance dredging
in the Siuslaw River navigation channel.  The need for that maintenance
dredging was recently underscored by U.S. Coast Guard in a letter dated
March 15, 2010, which characterized the Siuslaw as the most restricted
entrance bar on the coast of Oregon.  The dredging of the entrance bar
at Siuslaw is required annually in order to facilitate many of the other
uses of the area.

The Existing Water Quality and Ecology of the Site as Determined by
Available Data or by Trend Assessment or Baseline Survey (9).  Water and
sediment quality analyses conducted in the study area and experience
with past disposals in this region have not identified any adverse water
quality impacts from ocean disposal of dredged material (see Appendix
C).  The ecology of the offshore area, based mainly on fisheries and
benthic data, is that of a mobile sand community.  Neither the pelagic
or benthic communities should sustain any long-term impacts due to their
mobility and widespread occurrence off the Oregon Coast (see Appendix
A).

Potentiality for the Development or Recruitment of Nuisance Species in
the Disposal Site (10).  Nuisance species are any undesirable
organism(s) not previously found at a disposal site.  They are
transported to, or recruited to, a site because the disposal of dredged
materials creates an environment where they can establish.  Materials to
be dredged and transported to the proposed Siuslaw ocean disposal sites
historically have been classified as uncontaminated marine sands similar
to the sediment present at the sites.  Potential material dredged from
the upstream boat basin access channels may include fine-grained
material, however only limited quantities of fine-grained material from
the boat basin access channels have been placed in the ocean.  Any
material proposed for ocean disposal would be subject to sediment
quality evaluation.  Therefore, it is highly unlikely that nuisance
species could be established at the disposal site since habitat or
contaminant levels are unlikely to change over the long-term.

Existence at or in Close Proximity to the Site of any Significant
Natural or Cultural Features of Historical Importance (11).  The
cultural resources of the Siuslaw River study area is described in
detail in Appendix D.  The cultural resource that has the greatest
potential for impact by use of the proposed ocean disposal sites is
shipwrecks.  Potential shipwreck areas are evaluated in Appendix D. 
Historical records show that there are not any shipwrecks within the
area of the proposed Siuslaw ocean disposal sites.

SUMMARY OF COORDINATION UNDER OTHER APPLICABLE FEDERAL STATUTES

Federal Action

The proposed federal action consists of designation of two ocean
disposal sites at the mouth of the Siuslaw River.  Site designation does
not create or confer rights on any person to use a designated site upon
the effective date of site designation.  Persons or entities who seek to
use a site must first obtain a federal permit, or in the case of the
USACE, meet the substantive permit requirements, in order to actually
use a designated ocean dredged material disposal site.  This process
would include meeting the requirements of applicable statutes and
regulations.  The EPA recognizes, however, that site designation is
intended to have a practical result.  When sites are designated, it is
expected that such sites will be used by persons or entities meeting the
statutory and regulatory criteria for ocean disposal of dredged
material.  Therefore, actual disposal is an indirect effect of site
designation and is included in the evaluation of effects under the below
listed statutes.

Public Comments

EPA received three comments on the proposed rule.  All three comments
supported the Site designations.  One commenter asked whether the Sites
could be extended to run parallel to the coastline in order to create a
“speedbump” resulting in decreased wave energy and erosion on the
beach.  The final Sites include shallow areas (less than 50 ft), where
more material is expected to remain the littoral system, thereby
potentially decreasing potential beach erosion.  The creation of a
nearshore “speedbump” or berm would dissipate wave energy reaching
the beach, but would increase the wave height at the berm, potentially
creating an unacceptable safety risk.  The same commenter asked whether
the sandy dredged material could be used to restore an eroded beach
rather than be disposed in the Sites.  The sandy dredged material in the
vicinity of these Sites is already found in abundance onshore in the
nearby Oregon Dunes Recreation Area and onshore dune fields.  No eroded
beaches in the immediate vicinity of the Sites for which this material
is needed have been identified at this time.  Other general questions
included in this comment letter regarding timing of dredging and
disposal, sediment quality, alternatives, etc. are addressed elsewhere
in this document.

Endangered Species Act

In the Biological Assessment prepared for the proposed action (EPA 2009)
and subsequent supporting documents, EPA concluded that the indirect
effects of designation of the Siuslaw ocean disposal sites:

May affect, but is not likely to adversely affect OC coho salmon, SONCC
coho salmon, and Lower Columbia River coho salmon; no effect to critical
habitat for OC and SONCC coho salmon.

May affect, but is not likely to adversely affect any Chinook ESU; no
effect to critical habitat.

May affect, but is not likely to adversely affect Southern DPS green
sturgeon or designated critical habitat.

Is not likely to jeopardize the continued existence of Southern DPS
Pacific eulachon.

May affect, but is not likely to adversely affect Steller sea lion, blue
whale, fin whale, humpback whale, southern resident killer whale; no
effect to critical habitat.

May affect, but is not likely to adversely affect marbled murrelet,
short-tailed albatross, and brown pelican; no effect to critical
habitat.

No effect on western snowy plover, northern spotted owl, Oregon
silverspot butterfly, Fender’s blue butterfly, Kincaid’s lupine,
Willamette daisy, and Bradshaw’s desert parsley; no effect to critical
habitat.

The EPA initiated consultation under Section 7 of the Endangered Species
Act of 1973, as amended, 16 U.S.C. Sections 1531 to 1544, based on this
documentation with both the U.S. Fish and Wildlife Service and National
Marine Fisheries Service (NMFS) by letter dated July 22, 2009.  USFWS
concurred with EPA’s “may affect, not likely to adversely affect
determination for marbled murrelet, short-tailed albatross, and brown
pelican via letter dated August 24, 2009.  

	NMFS issued a Biological Opinion (BO) on April 21, 2010.  NMFS
concluded that EPA’s action is not likely to jeopardize the continued
existence of Oregon Coast (OC) coho salmon or southern green sturgeon
(Acipenser medirostris), or to destroy or adversely modify critical
habitat designated for green sturgeon.  NMFS also concluded that EPA’s
action would not likely adversely affect southern green sturgeon,
euchalon, eastern Stellar sea lions, blue whales, fin whales, humpback
whales, Southern Resident Killer whales, marine turtle species, or
critical habitat designated for southern green sturgeon or proposed for
green leatherback turtles.  NMFS concluded that dredging activities were
not interrelated to EPA’s action.  However, NMFS did make a finding
that disposal of dredged material at the Sites by the Corps, the
anticipated primary user of the Sites, was interrelated to EPA’s
action.  

	NMFS then focused its effects analysis on the effects of disposal at
the Sites.  Looking solely to the effects of disposal of dredged
material at the Sites by the Corps from the Corps’ Siuslaw River
Navigation project, NMFS estimated 19 juvenile OC coho salmon per year
were likely to be injured or killed by Corps activities.  NMFS
acknowledged that EPA’s action does not authorize or compel site use
and will not itself result in disposal of dredged material.  NMFS found
that all incidental take will occur at the project-specific level. 
Based on this finding, NMFS did not find a basis to provide a take
authorization in the current BO.  NMFS stated that all take
authorization will occur in subsequent site-specific consultations.  

	Finally NMFS included two discretionary conservation recommendations in
the BO.  The first recommendation suggested collaborating with NMFS and
the Corps on a methodology to evaluate the effects of dredging and
disposal on ESA-listed species.  The second recommendation suggested
undertaking a study to determine seasonal distribution, abundance, and
habitat use of salmon, sturgeon, and marine turtles in the nearshore
within and near the contour of designated ocean dredged material
disposal sites.  Such recommendations are purely advisory in nature. 
EPA appreciates that collaboration on a methodology could be helpful and
supports NMFS and Corps efforts in such an endeavor.  EPA also
appreciates that the study recommended by NMFS could contribute to the
scientific knowledge base but believes that NMFS, the expert Federal
agency on seasonal distribution, abundance and habitat use would be
better suited than EPA to carry out such a study.

Magnuson-Stevens Fishery Conservation and Management Act

In the Essential Fish Habitat (EFH) assessment prepared for the proposed
action (EPA 2009), it was concluded that the designation of the proposed
Siuslaw ocean disposal sites may adversely affect EFH for some flatfish
species (arrowtooth and starry flounder; English, sand, butter, petrale,
rock, and curlfin sole; and Pacific sanddab), big skate, spiny dogfish,
soupfin shark, four coastal pelagic fish species (northern anchovy,
pacific sardine, pacific mackerel, and jack mackerel), and Chinook/coho
salmon.  However, any effects are expected to be minor and temporary and
are not expected to reduce the quality and/or quantity in any
significant way for any EFH for these species.  Additionally, the
following measures were considered by EPA as a way to mitigate any
adverse impacts to designated EFH.  The EPA expects to incorporate these
measures into the SMMP for the proposed Siuslaw ocean disposal sites.

Dredged material to be disposed at the Siuslaw North and South ocean
disposal sites must determined to be suitable for unconfined, aquatic
disposal.  In the event that any dredged material is not suitable for
unconfined, aquatic disposal, the dredged material found unsuitable will
not be disposed at the Siuslaw ocean disposal sites, but will be placed
at acceptable upland disposal sites.

Bathymetry at the Siuslaw North and South ocean disposal sites will be
monitored on a regular basis to ensure that mounding is not occurring.

The EPA initiated consultation under the Magnuson-Stevens Fishery
Conservation and Management Act, 16 U.S.C. Section 1855(b), based on
this documentation with NMFS by letter dated July 22, 2009. 

NMFS response, dated April 16, 2010, concluded that the proposed action
and the effect of disposal at the Sites would have adverse effects on
designated EFH in the form of increased turbidity and decreases in prey
resources.  NMFS provided two “conservation recommendations” seeking
to implement the effects methodology and habitat usage studies included
in the ESA section of the BO.  EPA is responding to these
recommendations separately, by letter as required under the
Magnuson-Stevens Fishery Conservation and Management Act.  

Marine Mammal Protection Act

The EPA determined that the proposed action to designate the proposed
Siuslaw ocean disposal sites would not result in take or incidental take
of any protected marine mammal under the Marine Mammal Protection Act of
1972, as amended, 16 U.S.C. Sections 1361 to 1389.  The Biological
Assessment, which evaluated the possible effects on ESA listed marine
mammals, including Steller sea lions and whales, was provided the NMFS
Office of Protected Resources for review on July 22, 2009.  In their
April 16, 2010 BO, NMFS found that all effects of the action are
expected to be discountable or insignificant for ESA-listed marine
mammals.

Coastal Zone Management Act

EPA submitted a consistency determination pursuant to the Coastal Zone
Management Act, 16 U.S.C. Sections 1451 to 1465, to Oregon’s
Department of Land Conservation and Development (DLCD) by letter dated
January 19, 2010.  Via letter dated April 14, 2010, DLCD concurred with
the EPA that the proposed project is consistent to the maximum extent
practicable with the enforceable policies of the Oregon Coastal
Management Program.

National Historic Preservation Act

National Historic Preservation Act, as amended, 16 U.S.C. Sections 470
to 470a-2, which requires Federal agencies to take into account the
effect of their actions on districts, sites, buildings, structures, or
objects, included in, or eligible for inclusion in the National
Register.  The EPA determined that no historic properties would be
affected by the proposed undertaking, the designation of the proposed
Siuslaw ocean disposal sites.  The EPA provided that determination and
supporting evaluation to the State Historic Preservation Officer in the
Oregon Parks and Recreation Department by letter dated November 24,
2009.  The Tribal Governments, listed in the next section, were copied
on the historic property letter as consulting parties.  By letter dated
December 10, 2009, the State Archaeologist concurred that the project
would have no affect on any known cultural resources.

Tribal Consultation

Government-to-government consultation letters, dated November 24, 2009,
were sent to the Coquille Indian Tribe, the Cow Creek Band of Umpqua
Tribe of Indians, the Confederated Tribes of the Grand Ronde Community,
the Confederated Tribes of the Siletz Indians, and the Confederated
Tribes of the Coos, Lower Umpqua and Siuslaw Indians.  Tribal comments
were also solicited during the NHPA process.  Follow-up phone calls were
made to staff at each of the listed Tribes during January 2010.  No
Tribal comments were received.

SELECTION OF OCEAN DISPOSAL SITES FOR FORMAL DESIGNATION

Based on the evaluation of criteria contained in 40 CFR Part 228, the
Corps and EPA have determined that the Siuslaw River North and South
ocean disposal sites are suitable for designation.  The designation of
the ODMD Sites by EPA will be finalized through formal rulemaking
adopting this Environmental Assessment/MPRSA Criteria Evaluation and the
appendices to support this action.

LITERATURE CITED

Auth, T.D. and R.D. Brodeur.  2006.  Distribution and community
structure of ichthyoplankton off the coast of Oregon in 2000 and 2002. 
Marine Ecology Progress Series 319:199-213.

Auth, T.D., R.D. Brodeur, and K.M. Fisher.  2007.  Diel variation in
vertical distribution of an offshore ichthyoplankton community off the
Oregon Coast.  Fish Bulletin 105:313-326.

Brodeur, R.D., D.M. Gadomski, W.G. Pearcy, H.P. Batchelder, and C.B.
Miller.  1985.  Abundance and distribution of ichthyoplankton in the
upwelling zone off Oregon during anomalous El Niño conditions. 
Estuarine Coastal and Shelf Science 21:365-378.

EPA (U.S. Environmental Protection Agency).  July 2009.  Siuslaw River,
Oregon, Ocean Dredged Material Disposal Site Designation Biological
Assessment and Essential Fish Habitat Assessment.  Region 10, Seattle,
WA.

EPA and USACE (U.S. Environmental Protection Agency and U.S. Army Corps
of Engineers).  1984.  General Approach to Designation Studies for Ocean
Dredged Material Disposal Sites.  Washington D.C.

Hancock, D.R., P.O. Nelson, C.K. Sollitt, and K.J. Williamson.  1981. 
Coos Bay Offshore Disposal Site Investigation Interim Report, Phase I,
February 1979-March 1980.  Report to the U.S. Army Corps of Engineers,
Portland District.  Oregon State University, Corvallis.

Keister, J.E. and W.T. Peterson.  2003.  Zonal and seasonal variations
in zooplankton community structure off the central Oregon Coast,
1998-2000.  Progress in Oceanography 57:341-361.

NMFS (National Marine Fisheries Service).  2006.  Draft Community
Profiles for West Coast and North Pacific Fisheries - Washington,
Oregon, California, and other U.S. States.  Northwest Fisheries Science
Center and Alaska Fisheries Science Center.

Pearson, W.H., M.C. Miller, G.D. Williams, N.P. Kohn, and J.R. Skalski. 
February 2006.  Preliminary Assessment of Potential Impacts to Dungeness
Crabs from Disposal of Dredged Materials from the Columbia River.  PNNL
Report 15477, Pacific Northwest National Laboratory, Richland, WA.

Peterson, W.T. and Miller, C.B.  1977.  Seasonal cycle of zooplankton
abundance and species composition along the central Oregon Coast. 
Fishery Bulletin 75:717–724.

PISCO 2009. Partnership for Interdisciplinary Studies of Coastal Oceans,


	  HYPERLINK
"http://www.piscoweb.org/research/science-by-discipline/coastal-oceanogr
aphy/hypoxia" 
http://www.piscoweb.org/research/science-by-discipline/coastal-oceanogra
phy/hypoxia  

Richardson, S.L.  1973.  Abundance and distribution of larval fishes in
waters off Oregon, May-October 1969, with special emphasis on the
northern anchovy, Engraulis mordax.  Fishery Bulletin 71:697-711.

Richardson, S.L. and W.G. Pearcy.  1977.  Coastal and oceanic larvae in
an area of upwelling off Yaquina Bay, Oregon.  Fishery Bulletin
75:125-145.

SEF (Sediment Evaluation Framework).  May 2009.  Sediment Evaluation
Framework for the Pacific Northwest.  Prepared by U.S. Army Corps of
Engineers Seattle, Portland, and Walla Walla Districts and Northwestern
Division; U.S. Environmental Protection Agency Region 10; Washington
Departments of Ecology and Natural Resources; Oregon Department of
Environmental Quality; Idaho Department of Environmental Quality;
National Marine Fisheries Service; and U.S. Fish and Wildlife Service.

Sherman, T.  January 2007.  Port of Siuslaw Marina and Upper River
Channel Sediment Quality Evaluation Report.  U.S. Army Corps of
Engineers, Portland District, Portland, OR. 

Sherman, T.  February 2007.  Siuslaw River Sediment Quality Evaluation
Report.  U.S. Army Corps of Engineers, Portland District, Portland, OR.

Sullivan, B. and D. Hancock.  1977.  Zooplankton and Dredging, Research
Perspectives and Critical Review.  Water Resources Bulletin B(13).

USACE (U.S. Army Corps of Engineers).  1985.  Yaquina Bay Interim Ocean
Dredged Material Disposal Site Evaluation Study.  Portland District,
Portland, OR.

USACE.  1988a.  Chetco Ocean Dredged Material Disposal Site Evaluation,
Final Report.  Portland District, Portland, OR.

USACE.  1988b.  Rogue Ocean Dredged Material Disposal Site Evaluation,
Final Report.  Portland District, Portland, OR.

USACE.  1990.  Yaquina Bay Ocean Dredged Material Disposal Site Benthic
Infauna Evaluation.  Portland District, Portland, OR.

USACE.  1991.  Siuslaw River Sediment Evaluation, 1991.  Portland
District, Portland, OR.

USACE.  1992.  Siuslaw Ocean Dredged Material Disposal Site Evaluation,
Final Report.  Portland District, Portland, OR.

USACE.  1993.  Tongue Point Monitoring Program 1989-1992 Final Report. 
Prepared by U.S. Army Corps of Engineers, Portland District, Portland OR
and National Marine Fisheries Service, Northwest Fisheries Science
Center, Seattle, WA.

USACE.  1996.  Siuslaw River Sediment Quality Evaluation, 1996. 
Portland District.

USACE.  May 2001.  Siuslaw River Sediment Quality Evaluation.  Portland
District.

USACE.  2009.  Siuslaw Dredged Material Disposal Site, Benthic Infauna
And Demersal Fish Evaluation.  Prepared by Marine Taxonomic Services,
Ltd., Corvallis, OR.

Vavrinec, J., W.H. Pearson, N.P. Kohn, J.R. Skalski, C. Lee, K.D. Hall,
B.A. Romano, M.C. Miller, and T.P. Khangaonkar.  January 2007. 
Laboratory Assessment of Potential Impacts to Dungeness Crabs from
Disposal of Dredged Material from the Columbia River.  Pacific Northwest
National Laboratory, Richland, WA.

 Pursuant to the Ocean Dumping Regulations at 40 CFR § 227.13(b),
dredged material which meets the following criteria is environmentally
acceptable for ocean dumping without further testing:  (1) dredged
material composed primarily of sand, gravel, rock, or any other
naturally occurring bottom material with particle sizes larges than
silt, and the material is found in areas of high current or wave energy
such as streams with large bed loads, or coastal areas with shifting
bars and channels; or (2) dredged material for beach nourishment or
restoration and is composed primarily of sand, gravel, or shell with
particle sizes compatible with material on the receiving beaches; or (3)
when the material is substantially the same as the substrate at the
proposed disposal site and the site from which the material is taken is
far removed from known existing and historical sources of pollution such
that there is a reasonable assurance that the material has not been
contaminated by such pollution.  The use of the SEF screening levels
provides an additional safeguard for material that would otherwise meet
the regulatory criteria for environmentally acceptable material for
ocean dumping without further testing.

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Siuslaw River ODMDS Environmental Assessment and MPRSA Criteria
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