[Federal Register Volume 85, Number 62 (Tuesday, March 31, 2020)]
[Proposed Rules]
[Pages 17810-17818]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2020-06348]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R09-OAR-2014-0812; FRL-10006-85-Region 9]


Air Quality State Implementation Plan Approval; Nevada; 
Infrastructure Requirements for the 2010 Sulfur Dioxide National 
Ambient Air Quality Standard

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing to 
approve the remaining portion of a state implementation plan (SIP) 
revision submitted by the State of Nevada. This revision addresses the 
interstate transport requirements of the Clean Air Act (CAA) with 
respect to the 2010 1-hour sulfur dioxide (SO2) primary 
national ambient air quality standard (NAAQS). In this action, the EPA 
is proposing to determine that Nevada will not contribute significantly 
to nonattainment or interfere with maintenance of the 2010 1-hour 
SO2 NAAQS in any other state. We are taking comments on this 
proposal and plan to follow with a final action.

DATES: Comments must be received on or before April 30, 2020.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R09-
OAR-2014-0812 at http://www.regulations.gov, or via email to 
kelly.thomasp@epa.gov. For comments submitted at Regulations.gov, 
follow the online instructions for submitting comments. Once submitted, 
comments cannot be removed or edited from Regulations.gov. For either 
manner of submission, the EPA may publish any comment received to its 
public docket. Do not submit electronically any information you 
consider to be confidential business information (CBI) or other 
information whose disclosure is restricted by statute. Multimedia 
submissions (audio, video, etc.) must be accompanied by a written 
comment. The written comment is considered the official comment and 
should include discussion of all points you wish to make. The EPA will 
generally not consider comments or comment contents located outside of 
the primary submission (i.e., on the web, cloud, or other file sharing 
system). For additional submission methods, please contact the person 
identified in the FOR FURTHER INFORMATION CONTACT section. For the full 
EPA public comment policy, information about CBI or multimedia 
submissions, and general guidance on making effective comments, please 
visit http://www.epa.gov/dockets/commenting-epa-dockets.

FOR FURTHER INFORMATION CONTACT: Tom Kelly, EPA Region IX, (415) 972-
3856, kelly.thomasp@epa.gov.

SUPPLEMENTARY INFORMATION: Throughout this document, ``we,'' ``us,'' or 
``our'' refer to the EPA.
    Table of Contents
I. Background
II. Section 110(a)(2)(D)(i)(I)--Interstate Transport
    A. General Requirements and Historical Approaches for Criteria 
Pollutants
    B. Nevada's SIP Submittal
    C. The EPA's Evaluation of Prong 1--Significant Contribution to 
Nonattainment
    D. The EPA's Evaluation of Prong 2--Interference With 
Maintenance
III. Proposed Action

[[Page 17811]]

IV. Statutory and Executive Order Reviews

I. Background

    On June 22, 2010, the EPA promulgated a revised primary NAAQS for 
SO2 at a level of 75 parts per billion (ppb), based on a 3-
year average of the annual 99th percentile of 1-hour daily maximum 
concentrations.\1\ Pursuant to section 110(a)(1) of the CAA, states are 
required to submit SIPs meeting the applicable requirements of section 
110(a)(2) within three years after promulgation of a new or revised 
NAAQS or a shorter period as the EPA may prescribe. These SIPs, which 
the EPA has historically referred to as ``infrastructure SIPs,'' are to 
provide for the ``implementation, maintenance, and enforcement'' of 
such NAAQS, and the requirements are designed to ensure that the 
structural components of each state's air quality management program 
are adequate to meet the state's responsibility under the CAA. Section 
110(a) of the CAA imposes the obligation upon states to make a SIP 
submission to the EPA for a new or revised NAAQS, but the contents of 
individual state submissions may vary depending upon the facts and 
circumstances. The content of the revisions proposed in SIP submissions 
may also vary depending upon what provisions are already contained in 
the state's approved SIP.
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    \1\ 75 FR 35520.
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    On June 3, 2013, the State of Nevada submitted a revision to its 
SIP addressing the requirements of section 110(a)(2) of the CAA with 
respect to the 2010 SO2 NAAQS (``2013 Nevada SIP 
revision''). On November 3, 2015, the EPA partially approved and 
partially disapproved portions of the 2013 Nevada SIP revision for the 
2010 SO2 NAAQS.\2\ However, at that time, the EPA did not 
take action on the section 110(a)(2)(D)(i)(I), interstate transport 
portion of the 2013 Nevada SIP revision.\3\ The EPA is now proposing to 
act on that portion of the 2013 Nevada SIP revision for the 2010 
SO2 NAAQS.
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    \2\ The EPA's final rule (80 FR 67652) addressed all elements of 
the three separate SIP submittals for 2008 ozone, 2010 nitrogen 
oxides, and 2010 SO2, with the exception of interstate 
transport requirements (prongs 1 and 2) for 2008 ozone, addressed in 
a subsequent rulemaking (82 FR 9164, February 3, 2017), and prongs 1 
and 2 of the interstate transport requirements for 2010 
SO2 addressed in this proposal.
    \3\ In addition to section 110(a)(2)(D)(i)(I) provisions for 
SO2, the EPA did not act on the section 
110(a)(2)(D)(i)(I) provisions of Nevada's SIP submittal for the 2008 
ozone NAAQS that was part of the same rulemaking. The EPA approved 
the section 110(a)(2)(D)(i)(I) portion of Nevada's submittal for the 
2008 ozone NAAQS in a subsequent rulemaking, 82 FR 9164 (February 3, 
2017).
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II. Section 110(a)(2)(D)(i)(I)--Interstate Transport

A. General Requirements and Historical Approaches for Criteria 
Pollutants

    Section 110(a)(2)(D)(i)(I) requires states to include in their SIPs 
provisions prohibiting any source or other type of emissions activity 
in one state from emitting any air pollutant in amounts that will 
contribute significantly to nonattainment, or interfere with 
maintenance, of the NAAQS in another state. The two clauses of this 
section are referred to as prong 1 (significant contribution to 
nonattainment) and prong 2 (interference with maintenance of the 
NAAQS). The EPA commonly refers to SIP revisions addressing the 
requirements of section 110(a)(2)(D)(i)(I) as ``good neighbor SIPs'' or 
``interstate transport SIPs.''
    The EPA's most recent infrastructure SIP guidance, the September 
13, 2013 ``Guidance on Infrastructure State Implementation Plan (SIP) 
Elements under Clean Air Act Sections 110(a)(1) and 110(a)(2),'' did 
not explicitly include criteria for how the Agency would evaluate 
infrastructure SIP submissions intended to address section 
110(a)(2)(D)(i)(I).\4\ With respect to certain pollutants, such as 
ozone and particulate matter, the EPA has addressed interstate 
transport in eastern states in the context of regional rulemaking 
actions that quantify state emissions reduction obligations.\5\ In 
other actions, such as the EPA actions on western interstate transport 
SIPs addressing ozone and particulate matter, the EPA has considered a 
variety of factors on a case-by-case basis to make a weight of evidence 
determination as to whether emissions from one state interfere with the 
attainment and maintenance of the NAAQS in another state. In such 
actions, the EPA has considered available information such as current 
air quality, emissions data and trends, meteorology, and topography.\6\
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    \4\ At the time the September 13, 2013 guidance was issued, the 
EPA was litigating challenges raised with respect to its Cross State 
Air Pollution Rule (``CSAPR''), 76 FR 48208 (Aug. 8, 2011), designed 
to address the CAA section 110(a)(2)(D)(i)(I) interstate transport 
requirements with respect to the 1997 ozone and the 1997 and 2006 
PM2.5 NAAQS. CSAPR was vacated and remanded by the D.C. 
Circuit in 2012 pursuant to EME Homer City Generation, L.P. v. EPA, 
696 F.3d 7. The EPA subsequently sought review of the D.C. Circuit's 
decision by the Supreme Court, which was granted in June 2013. As 
the EPA was in the process of litigating the interpretation of 
section 110(a)(2)(D)(i)(I) at the time the infrastructure SIP 
guidance was issued, the EPA did not issue guidance specific to that 
provision. The Supreme Court subsequently vacated the D.C. Circuit's 
decision and remanded the case to that court for further review. 134 
S.Ct. 1584 (2014). On July 28, 2015, the D.C. Circuit issued a 
decision upholding CSAPR, but remanding certain elements for 
reconsideration. 795 F.3d 118.
    \5\ See, e.g., NOX SIP Call, 63 FR 57371 (October 27, 
1998); Clean Air Interstate Rule (CAIR), 70 FR 25172 (May 12, 2005); 
CSAPR, 76 FR 48208 (August 8, 2011); CSAPR Update, 81 FR 74504 
(October 26, 2016).
    \6\ See, e.g., Approval and Promulgation of Implementation 
Plans; State of California; Interstate Transport of Pollution; 
Significant Contribution to Nonattainment and Interference With 
Maintenance Requirements, Proposed Rule, 76 FR 14616, 14616-14626 
(March 17, 2011); Final Rule, 76 FR 34872 (June 15, 2011); Approval 
and Promulgation of State Implementation Plans; State of Colorado; 
Interstate Transport of Pollution for the 2006 24-Hour 
PM2.5 NAAQS, Proposed Rule, 80 FR 27121, 27124-27125 (May 
12, 2015); Final Rule, 80 FR 47862 (August 10, 2015).
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1. The EPA's Approach for Addressing the Interstate Transport 
Requirements of the 2010 Primary SO2 NAAQS in Nevada
    As previously noted, section 110(a)(2)(D)(i)(I) requires an 
evaluation of any source or other type of emissions activity in one 
state and how emissions from these source categories may impact air 
quality in other states. The EPA believes that a reasonable starting 
point for determining which sources and emissions activities in Nevada 
are likely to impact downwind air quality with respect to the 2010 
SO2 NAAQS is to use information in the National Emissions 
Inventory (NEI).\7\ The NEI is a comprehensive and detailed estimate of 
air emissions of criteria pollutants, criteria pollutant precursors, 
and hazardous air pollutants from air emissions sources, that is 
updated every three years using information provided by the states. At 
the time of this proposed rulemaking, the most recently available 
complete dataset is the 2014 NEI. The analysis in this proposed 
rulemaking also relies on facility-reported emissions data, the most 
recent of which is for 2017.\8\ In addition, our analysis uses trends 
data, which the EPA prepares annually.\9\ Trends data include facility 
reported emissions data and data extrapolated by the EPA from the most 
recent NEI year.
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    \7\ For additional information, see: https://www.epa.gov/air-emissions-inventories/national-emissions-inventory.
    \8\ Data downloaded on October 9, 2019, from: https://www.epa.gov/air-emissions-inventories/2017-national-emissions-inventory-nei-data, dataset: 2017NEI_Aug2019_PT, and contained in 
the docket for this notice.
    \9\ State Annual Emission Trend data can be downloaded from 
https://www.epa.gov/air-emissions-inventories/air-pollutant-emissions-trends-data. Trends data does not include event emissions, 
such as forest fires.
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    Although SO2 is emitted from similar point and nonpoint 
sources, as is

[[Page 17812]]

directly emitted fine particulate matter (PM2.5) \10\ and 
the precursors to both ozone and PM2.5, interstate transport 
of SO2 is unlike the transport of PM2.5 or ozone 
because SO2 emissions sources usually do not have long range 
SO2 impacts. The transport of SO2 relative to the 
1-hour NAAQS is more analogous to the transport of lead (Pb) relative 
to the Pb NAAQS in that emissions of SO2 typically result in 
1-hour pollutant impacts of possible concern only near the emissions 
source. However, ambient 1-hour concentrations of SO2 do not 
decrease as quickly with distance from the source as do 3-month average 
concentrations of Pb, because SO2 gas is not removed by 
deposition as rapidly as are Pb particles and because SO2 
typically has a higher emissions release height than Pb. Emitted 
SO2 has wider ranging impacts than emitted Pb, but it does 
not have such wide-ranging impacts that its treatment in a manner 
similar to ozone or PM2.5 would be appropriate. Accordingly, 
while the approaches that the EPA has adopted for ozone or 
PM2.5 transport would be too regionally focused for 
SO2, the approach for Pb transport would be too tightly 
circumscribed to the source. SO2 transport is therefore a 
unique case and requires a different approach.
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    \10\ Includes particles with an aerodynamic diameter of less 
than or equal to 2.5 micrometers.
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    In this proposed rulemaking, as in prior SO2 transport 
analyses, we focus on a 50 kilometer (km) wide zone because the 
physical properties of SO2 result in relatively localized 
pollutant impacts near an emissions source that drop off with distance. 
Given the properties of SO2, the EPA selected a spatial 
scale with dimensions from four to 50 km from point sources--the 
``urban scale''--to assess trends in area-wide air quality that might 
impact downwind states.\11\ As discussed further in section III.B, the 
EPA selected the urban scale as appropriate for assessing trends in 
both area-wide air quality and the effectiveness of large-scale 
pollution control strategies at SO2 point sources. The EPA's 
selection of this transport distance for SO2 is based upon 
40 CFR 58, Appendix D, Section 4.4.4(4), ``Urban scale'', which states 
that measurements in this scale would be used to estimate 
SO2 concentrations over large portions of an urban area with 
dimensions from four to 50 km. The American Meteorological Society/
Environmental Protection Agency Regulatory Model is the EPA's preferred 
modeling platform for regulatory purposes for near-field dispersion of 
emissions for distances up to 50 km. (Appendix W of 40 CFR part 
51).\12\ Thus, the EPA has applied the 50-km zone as a reasonable 
distance to evaluate emissions source impacts into neighboring states 
and to assess air quality monitors within 50 km of the State's border.
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    \11\ For the definition of spatial scales for SO2, 
see 40 CFR part 58, Appendix D, section 4.4 (``Sulfur Dioxide 
(SO2) Design Criteria''). For further discussion on how 
the EPA applies these definitions with respect to interstate 
transport of SO2, see the EPA's notice of proposed 
rulemaking on Connecticut's SO2 transport SIP. 82 FR 
21351, 21352, 21354 (May 8, 2017).
    \12\ The EPA provided non-binding technical assistance document 
(i.e., ``SO2 NAAQS Designations Modeling Technical 
Assistance Document'') to assist states and other parties in their 
efforts to characterize air quality through air dispersion modeling 
for sources that emit SO2. This draft document was first 
released in spring 2013. Revised drafts were released in February 
and August of 2016 (see https://www.epa.gov/sites/production/files/2016-06/documents/so2modelingtad.pdf).
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    Current implementation strategies for the 2010 primary 
SO2 NAAQS include the flexibility to characterize air 
quality for stationary sources via either data collected at ambient air 
quality monitors sited to capture the points of maximum concentration, 
or air dispersion modeling.\13\ The EPA's assessment of SO2 
emissions from fuel combustion categories in Nevada and their potential 
on neighboring states is informed by all available data at the time of 
this rulemaking and include: SO2 ambient air quality; 
SO2 emissions and emissions trends; SIP-approved regulations 
that directly address SO2; and other SIP-approved 
regulations, which may yield reductions of SO2. This notice 
describes the EPA's weight of evidence evaluation of the 2013 Nevada 
SIP revision to satisfy the requirements of CAA section 
110(a)(2)(D)(i)(I).\14\
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    \13\ Data Requirements Rule for the 2010 1-Hour Sulfur Dioxide 
(SO2) Primary National Ambient Air Quality Standard (80 
FR 51052, August 21, 2015).
    \14\ The EPA notes that the evaluation of other states' 
satisfaction of section 110(a)(2)(D)(i)(I) for the 2010 
SO2 NAAQS can be informed by similar factors found in 
this proposed rulemaking but may not be identical to the approach 
taken in this or any future rulemaking for Nevada, depending on 
available information and state-specific circumstances.
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B. Nevada's SIP Submittal

1. Administrative Requirements
    On June 3, 2013, the Nevada Division of Environmental Protection 
(NDEP) submitted to the EPA the 2013 Nevada SIP revision.\15\ The 
submittal includes the following:
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    \15\ Letter dated June 3, 2013, from Colleen Cripps, 
Administrator, NDEP, to Jared Blumenfeld, Regional Administrator, 
EPA Region IX.
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     The Nevada Division of Environmental Protection Portion of 
the Nevada State Implementation Plan for the 2010 Sulfur Dioxide 
Primary NAAQS, and appendices, June 3, 2013;
     State Implementation Plan Revision to Meet the Sulfur 
Dioxide Infrastructure SIP Requirements of the Clean Air Act Sec.  
110(a)(2), and attachments Clark County, Nevada, May 29, 2013;
     The Washoe County Portion of the Nevada State 
Implementation Plan to Meet the Sulfur Dioxide Infrastructure SIP 
Requirements of Clean Air Act Sec.  110(a)(2), and attachments, March 
28, 2013
    The submittal was deemed complete by operation of law on December 
3, 2013.
    The Washoe and the NDEP portions of the submittal state that they 
are not required to make submittals addressing the requirements of CAA 
section 110(a)(2)(D)(i)(I) and cite to a November 19, 2012 memo from 
EPA Administrator Gina McCarthy, which outlined the EPA's intention to 
abide by a 2012 D.C. Circuit decision.\16\
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    \16\ EME Homer City Generation, L.P. v. E.P.A. 696 F.3d 7. The 
EME Homer City Generation, L.P. v. E.P.A. decision addressed CSAPR 
promulgated by the EPA to address the interstate transport 
requirements under section 110(a)(2)(D)(i)(I) with respect to the 
1997 ozone NAAQS, the 1997 PM2.5 NAAQS, and the 2006 
PM2.5 NAAQS. Among other things, the D.C. Circuit held 
that states did not have an obligation to submit SIPs addressing 
section 110(a)(2)(D)(i)(I) interstate transport requirements as to 
any NAAQS until the EPA first quantified each state's emissions 
reduction obligation. On March 25, 2016, the Supreme Court reversed 
the D.C. Circuit opinion, vacating the EME Homer City Generation, 
L.P. v. E.P.A. decision.
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    Despite stating in the NDEP portion of the submittal that it was 
not obligated to address the requirements of CAA section 
110(a)(2)(D)(i)(I), the NDEP included Appendix C ``Interstate Transport 
Analysis for the 2010 Sulfur Dioxide Primary National Ambient Air 
Quality Standard'' (``Appendix C'' or ``transport analysis'') to 
address the aforementioned CAA requirements.
2. The NDEP's Transport Analysis
    As the NDEP's portion of the submittal explains, the Clark County 
Department of Air Quality (Clark County) and Washoe County Board of 
Health (Washoe County) regulate air pollution within their respective 
counties, with the exception of fossil-fuel-fired steam generators. The 
NDEP regulates air pollution in all other counties of the State as well 
as fossil-fuel-fired steam generators throughout the State, including 
Clark County and Washoe County.
    The following summarizes the NDEP's rationale for concluding that 
transport of SO2 from Nevada would not significantly 
contribute to nonattainment, or interfere with

[[Page 17813]]

maintenance, of the 2010 SO2 NAAQS in other states.\17\
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    \17\ See C-1 to C-9 (Appendix C) of the NDEP portion of the 2013 
Nevada SIP revision.
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    a. Summary of Nevada's transport analysis regarding nonattainment 
receptors in contiguous states: Arizona and Utah.
    The NDEP's transport analysis cites Clean Air Status and Trends 
Network (CASTNET) monitoring data in Nevada, Utah, Montana, Colorado, 
and Arizona. CASTNET data measure air quality in areas where urban 
influences are minimal, and, thus, are representative of regional 
background levels of air pollution.\18\ According to the NDEP, average 
weekly and seasonal SO2 concentrations from six national 
parks and one national monument in Nevada, Utah, Montana, Colorado, and 
Arizona were below 2 ppb from 2007 to 2012, ``indicating that the 
regional SO2 background concentrations are relatively low, 
which in turn implies that the bulk of the SO2 in the urban 
receptor areas is locally generated and not a regional or transport 
phenomenon.''
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    \18\ The NDEP reviewed CASTNET data at six national parks and 
one national monument in: Nevada (Great Basin National Park), Utah 
(Canyonlands National Park), Montana (Glacier National Park), 
Colorado (Mesa Verde National Park), and Arizona (Grand Canyon 
National Park, Petrified Forest National Park, and Chiricahua 
National Monument).
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    The Nevada transport analysis further explains that Arizona's only 
nonattainment receptors are the Hayden and Miami SO2 
nonattainment planning areas, located in Gila County and Pinal County, 
respectively. Total SO2 emissions from Gila and Pinal 
counties were 29,470 tons from the 2008 NEI. The NDEP notes that 
Nevada's nearest SO2 source, the recently closed Reid 
Gardner Generating Station,\19\ is 305 miles (490 km) from the Miami 
nonattainment area and 330 miles (530 km) from the Hayden nonattainment 
area and emitted only 941 tons of SO2 in 2008, which, for 
illustrative purposes, was about three percent of the SO2 
emissions originating from the Miami and Hayden copper smelters.\20\ 
Additionally, the NDEP states that meteorological data show the 
prevailing wind direction in the southern part of the State is from the 
south-southwest blowing mainly north-northeast (indicating that winds 
in Nevada are generally not blowing south-southeast from Nevada toward 
Hayden and Miami in Arizona).\21\
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    \19\ As discussed in the EPA's rescission of regional haze 
federal implementation plan for the Reid Gardner Generating Station, 
three of the Reid Gardner Generating Station's coal-fired boilers 
ceased operation in 2014 and the fourth ceased operation in 2017. 
See 83 FR 24952, May 31, 2018.
    \20\ This quantity was based on the 2008 NEI.
    \21\ Discussed at C-2 and documented in Figure C.1, Las Vegas, 
Nevada, Wind Rose Plot, 2003-2011, of the 2013 SIP submittal.
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    For Utah, the NDEP states that Salt Lake and Tooele counties are 
classified as nonattainment for the 24-hour and annual 1971 
SO2 NAAQS, but that the counties have not violated those 
NAAQS since 1981.\22\ The Nevada transport analysis concludes that no 
areas in Utah are likely to exceed the 2010 NAAQS based on monitoring 
data indicating that elevated SO2 levels in Salt Lake and 
Tooele counties ceased decades ago, and CASTNET data demonstrating low 
levels of regional background SO2.
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    \22\ The entire state of Utah is attainment/unclassifiable for 
the 2010 SO2 NAAQS, see https://www.ecfr.gov/cgi-bin/text-idx?SID=dab140f1447715b3662a38473ba7df7d&mc=true&node=se40.20.81_1345&rgn=div8 (last visited on May 1, 2019).
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    b. Summary of Nevada's transport analysis regarding attainment 
areas in one contiguous western state: Arizona.
    Nevada's transport analysis identifies four maintenance areas for 
the 1971 SO2 NAAQS in Arizona: The Ajo, Douglas, Morenci, 
and San Manuel SO2 planning areas. In its analysis, Nevada 
summarizes the approved maintenance plans for the areas and states that 
copper smelters were historically the primary source of SO2 
emissions. The transport analysis states that only one smelter, located 
in the San Manuel SO2 maintenance area, remains operational 
and that there have been no recorded monitoring violations of the 
SO2 NAAQS in any of these areas since the mid-1980s.
    c. Summary of Nevada's transport analysis regarding nonattainment 
and maintenance receptor areas in non-contiguous states: Missouri, 
Montana, and New Mexico.
    Nevada's transport analysis also examined transport to 
nonattainment receptors in Missouri and Montana and determined that 
SO2 emissions from Nevada do not contribute to nonattainment 
in those areas based on a comparison of the emissions inventories in 
those states and Nevada, wind patterns, and the distance between those 
states and Nevada.
    In addition, the Nevada transport analysis evaluated maintenance 
receptors in New Mexico and determined that Nevada does not interfere 
with maintenance in that state based on comparison of the emissions 
inventories in New Mexico and Nevada, overall regional background 
levels of SO2, and the distance between New Mexico and 
Nevada.

C. The EPA's Evaluation of Prong 1--Significant Contribution to 
Nonattainment

    Prong 1 of the good neighbor provision requires state plans to 
prohibit emissions that will significantly contribute to nonattainment 
of a NAAQS in another state. In order to evaluate whether Nevada met 
prong 1 for the 2010 SO2 NAAQS, the EPA evaluated the 2013 
Nevada SIP revision with respect to the following two factors: (1) 
SO2 ambient air quality in Nevada and neighboring states; 
and (2) SO2 emissions sources in Nevada and neighboring 
states. Based on the detailed discussion of these factors below, the 
EPA proposes to find that Nevada's SIP meets the interstate transport 
requirements of CAA Section 110(a)(2)(D)(i)(I), prong 1, for the 2010 
SO2 NAAQS.
1. SO2 Ambient Air Quality in Nevada and Neighboring States
    First, the EPA reviewed ambient air quality data in Nevada and 
neighboring states to see whether there were any monitoring sites with 
elevated SO2 concentrations that might warrant further 
investigation with respect to interstate transport of SO2 
from emissions sources near any given monitor. As shown in Table 1, 
there are no violating design values \23\ between 2014 and 2018 in 
Nevada or neighboring states apart from monitors located in the Hayden 
and Miami nonattainment areas in Arizona.\24\
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    \23\ The 2010 l-hour SO2 NAAQS is met at an ambient 
air quality monitoring site when the three-year average of the 
annual (99th percentile) of the daily maximum l-hour average 
concentrations is less than or equal to 75 ppb. This metric is 
referred to as a ``design value'' (in this document referred to as 
the ``SO2 l-hour design value''). The EPA's data handling 
conventions and computations necessary for determining compliance 
with the 2010 1-hour SO2 NAAQS are provided in 40 CFR 
part 50, appendix T.
    \24\ Data for Table 1 is contained in the docket for this 
notice. See SO2 monitor report 2018.pdf, SO2 
monitor report 2017.pdf, and SO2 monitor report 2016.pdf.

[[Page 17814]]



                                              Table 1--SO2 Design Values for Nevada and Neighboring States
                                                                          [ppb]
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                                                                                             Distance to Nevada
           Monitoring site                       State                     Area                 border  (km)        2014-2016    2015-2017    2016-2018
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32-003-0540..........................  NV......................  Las Vegas..............  32 km to AZ and 62 km              7            6            6
                                                                                           to CA.
32-031-0016..........................  NV......................  Reno...................  17 km to CA............            5            5            4
04-007-1001..........................  AZ......................  Hayden NAA\a\..........  419....................          280          295          282
04-007-0009..........................  AZ......................  Miami NAA..............  391....................          146        NA\b\           NA
04-007-0011..........................  AZ......................  Miami NAA..............  391....................          200          221          175
04-007-0012..........................  AZ......................  Miami NAA..............  389....................          194          159          127
04-012-8000..........................  AZ......................  Wenden.................  130....................            3           NA           NA
04-013-3002..........................  AZ......................  Phoenix................  193....................            7            7            7
04-013-9812..........................  AZ......................  Phoenix................  290....................            8            9            8
04-013-9997..........................  AZ......................  Phoenix................  287....................            5            6            6
04-013-1028..........................  AZ......................  Tucson.................  452....................            4            3            2
06-013-0002..........................  CA......................  Concord................  212....................            8            7            8
06-013-1002..........................  CA......................  Bethel Island..........  181....................            4            4            3
06-019-0011..........................  CA......................  Fresno.................  171....................            6            6            6
06-067-0006..........................  CA......................  Arden-Arcade...........  126....................            7            8            2
06-071-0306..........................  CA......................  Victorville............  210....................           18            3            3
06-071-1234..........................  CA......................  Trona..................  110....................            6           13            6
(26-31 Other Monitoring Locations)...  CA......................  All Other Monitors in    216-405................         1-18         1-14         1-16
                                                                  California\c\.
16-001-0010..........................  ID......................  near Boise.............  178....................            4            3            3
16-005-0004..........................  ID......................  Pocatello..............  162....................           39           38           44
16-029-0031..........................  ID......................  Soda Springs...........  216....................           26           30           27
41-051-0080..........................  OR......................  Portland...............  442....................            3            3            3
49-035-3006..........................  UT......................  Salt Lake City.........  183....................           NA           NA           NA
49-035-2005..........................  UT......................  Midvale................  182....................           NA           NA           NA
49-035-3010..........................  UT......................  Salt Lake City.........  178....................           NA           NA           NA
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\a\ NAA--nonattainment area.
\b\ NA--Not available for monitors lacking a valid design value in the given year due to missing or incomplete data.
\c\ This table only includes specific results for monitors within 215 km of the Nevada-California border. Other California monitors are summarized in
  one row.

    Table 2 lists the annual 99th percentiles for SO2 
monitors that collected either three or four complete quarters of data 
in the specified year but lacked three consecutive years of complete 
data (i.e., a design value) like the monitors in Table 1. Again, the 
only monitor exceeding the 2010 SO2 NAAQS is located in the 
Miami nonattainment area.

                             Table 2--Annual SO2 99th Percentiles for Monitors in Neighboring States Lacking a Design Value
                                                                          [ppb]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                            Distance to
           Monitoring site                       State                     Area           Nevada  border       2016            2017            2018
                                                                                               (km)
--------------------------------------------------------------------------------------------------------------------------------------------------------
04-007-0009..........................  AZ......................  Miami NAA \a\..........             391             120         N/A \b\              NA
49-035-3006..........................  UT......................  Salt Lake City.........             183             N/A               4               3
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ NAA--nonattainment area.
\b\ N/A--Not available, less than three complete quarters of data were collected for this monitor in the given year.

    In concluding that Nevada would not impact receptors in the Hayden 
or Miami nonattainment areas in Arizona, Nevada's submittal noted 
several factors, including the prevailing wind direction in Las Vegas 
to the south and southwest and the significant distance, more than 300 
miles (482 km), between the nonattainment areas and the nearest large 
generator of SO2 emissions in southern Nevada, the now 
closed Reid Gardner Generating Station. At the closest point at 
Nevada's southern tip, the Hayden and Miami nonattainment areas are 350 
km from the Nevada border, far outside the range within which we might 
expect a potential impact from SO2 sources located in 
Nevada, given the localized range of potential 1-hour SO2 
emissions.
    The data presented in Table 1 show that Nevada's SO2 
monitors, with sufficient data to produce valid 1-hour SO2 
design values, indicate that monitored 1-hour SO2 
concentrations in Nevada are between 5 percent (%) and 9% of the 75 ppb 
1-hour SO2 NAAQS. The Reno monitor is located within 50 km 
of the California border and the Las Vegas monitor is located within 50 
km of the Arizona border. The highest SO2 concentration 
within 300 km of Nevada is the Pocatello Idaho monitor, which is 59% of 
the NAAQS based on the 2018 design value and 162 km from the Nevada 
border. The low level of SO2 at these air quality monitors 
in and near Nevada do not, by themselves, indicate any particular 
location that would warrant further investigation with respect to 
SO2 emissions sources that might significantly contribute to

[[Page 17815]]

nonattainment in neighboring states. However, because the monitoring 
network is not necessarily designed to find all locations of high 
SO2 concentrations, this observation is not sufficient 
evidence by itself of an absence of impact at all locations in the 
neighboring states. We have therefore also conducted a source-oriented 
analysis.
2. Analysis of SO2 Emissions Sources in Nevada and 
Neighboring States
    To understand the potential for Nevada's emissions to contribute 
significantly to nonattainment in another state, we begin with a 
summary of the State's SO2 emissions in Table 3 from the 
2014 NEI.\25\ The EPA believes a reasonable starting point for 
determining which sources and emissions activities in Nevada are likely 
to impact downwind air quality in other states with respect to the 2010 
1-hour SO2 NAAQS is by using information in the EPA's 2014 
NEI. The NEI is a comprehensive and detailed estimate of air emissions 
for criteria pollutants, criteria pollutant precursors, and hazardous 
air pollutants from air emissions sources; it is updated every three 
years using information provided by the states and other information 
available to the EPA. The 2014 NEI (version 2) is the most recently 
available complete and quality assured dataset of the NEI that includes 
all emissions categories.
---------------------------------------------------------------------------

    \25\ The EPA's NEI is available at https://www.epa.gov/air-emissions-inventories/national-emissions-inventory.

  Table 3--Summary of 2014 NEI SO2 Emissions Data for Nevada by Source
                               Category a
------------------------------------------------------------------------
                                                          SO2 emissions
                       Category                          (tons per year)
 
------------------------------------------------------------------------
Fuel Combustion, Electric Generation..................            10,277
Fuel Combustion Industrial............................             2,967
Fires.................................................               840
Mobile................................................               556
Fuel Combustion Commercial............................               642
Waste Disposal........................................               293
Industrial Processes (non-combustion).................               540
Other.................................................                61
                                                       -----------------
    Total Nevada SO2 Emissions........................            16,178
------------------------------------------------------------------------
\a\ The sum of the categories does not add to the total due to rounding.

    As shown in Table 3, the majority of SO2 emissions in 
Nevada originate from fuel combustion at point sources. In 2014, 
SO2 emissions from fuel combustion point sources accounted 
for approximately 85% of the State's SO2 emissions.\26\ With 
the closure of the Reid Gardner Generating Station, which accounted for 
over 15% of overall SO2 emissions in the 2014 NEI, the 
SO2 state-wide total should be substantially smaller once 
the 2017 emissions inventory is released. The next largest category of 
emissions is fire. According to the 2014 NEI, approximately 92% of fire 
emissions are from wildfires, which vary in location and quantity of 
emissions from year to year, while most of the other fire emissions 
come from prescribed burning. Of the remaining emissions (mobile, waste 
disposal, non-combustion industrial, and other, which make up 
approximately 9% of the state total), slightly more than half (about 5% 
of the state-wide total or 880 tons) originate in Clark County, which 
contains approximately 75% of Nevada's population, and the rest 
originate elsewhere throughout the State.
---------------------------------------------------------------------------

    \26\ Nevada's fuel combustion point sources listed in Table 3, 
for the purposes of this action, are comprised of all of the ``Fuel 
Combustion'' categories, i.e., Fuel Combustion, Electric Generation; 
Fuel Combustion, Industrial; and Fuel Combustion, Commercial.
---------------------------------------------------------------------------

    Emissions from the other listed source categories are more 
dispersed throughout the State, with the exception of McCarran Airport 
and Sunrise Landfill analyzed later in this notice. Due to the 
dispersed nature of these other source categories, their emissions are 
less likely to cause high ambient concentrations when compared to a 
point source on a ton-for-ton basis. Based on the EPA's analysis of the 
2014 NEI SO2 emissions data, the EPA considers it to be 
appropriate to focus the discussion on SO2 emissions from 
Nevada's larger point sources (i.e., those emitting over 50 tons per 
year (tpy) of SO2), which are located within the ``urban 
scale,'' i.e., within 50 km of one or more state borders.
    Specifically, in 2014 60 percent of the statewide SO2 
emissions came from two facilities.\27\ The first, the North Valmy 
Generating Station, is 124 km from the state border, well beyond the 
50-km threshold zone considered to be a reasonable distance to evaluate 
emissions source impacts to neighboring states for purposes of this 
analysis. In addition, EPA recently considered a modeling analysis 
submitted by the NDEP to support its recommendation that the EPA 
designate the entire State of Nevada as attainment/unclassifiable for 
the 2010 SO2 NAAQS.\28\ The modeling was conducted in 
response to the Final Data Requirements Rule for the 2010 1-Hour 
SO2 Primary NAAQS.\29\ As required by the rule, Nevada 
identified the North Valmy Generating Station as a facility emitting 
more than 2,000 tpy of SO2 in 2014.\30\ Based on modeling 
that shows a maximum SO2 concentration of 63 ppb, the EPA 
determined that the North Valmy Generating Station ``is not modeled to 
cause or contribute to violations of the 2010 SO2 [NAAQS],'' 
and the EPA designated the area around North Valmy Generating Station, 
along with the rest of the State, as attainment/unclassifiable for the 
2010 SO2 NAAQS.\31\
---------------------------------------------------------------------------

    \27\ In 2014, the North Valmy Generating Station emitted 7,430 
tons of SO2 and the Reid Gardner Generating Station 
emitted 2,506 tons of SO2, per the 2014 NEI.
    \28\ 83 FR 1098 (January 9, 2018). The North Valmy Generating 
Station is specifically discussed in Chapter 26, Technical Support 
Document: Intended Round 3 Area Designations for the 2010 1-Hour 
SO2 Primary National Ambient Air Quality Standard, EPA, 
August 2017, which is available in the docket for today's notice.
    \29\ This Rule required sources emitting more than 2,000 tpy of 
SO2 to characterize their air quality impacts through 
ambient air monitoring or dispersion modeling.
    \30\ The North Valmy Generating Station generated 1,588 tons of 
SO2 emissions in 2017, per the 2017 NEI, which includes 
only facility reported point source emissions data at this time.
    \31\ Technical Support Document: Chapter 26 Intended Round 3 
Area Designations for the 2010 1-Hour SO2 Primary 
National Ambient Air Quality Standard for Nevada, EPA, page 27, 
August 2017.
---------------------------------------------------------------------------

    The North Valmy Generating Station is located 124 km from the 
Nevada-Oregon border and 125 km from the Nevada-Idaho border. Based on 
2017 facility reported emissions data, Nevada has no other facilities 
emitting more than 50 tpy of SO2 within 50 km of the State's 
border that could potentially combine with the emissions from the North 
Valmy Generating Station to contribute to nonattainment in the nearby 
states of Idaho and Oregon. The closest facility to the North Valmy 
Generating Station is the TS Power Plant, which is slightly more than 
50 km from the North Valmy facility and more than 130 km from the 
Nevada-Idaho and Nevada-Oregon borders. This information supports the 
EPA's proposed conclusion that the North Valmy facility, in combination 
with Nevada's other SO2 emissions sources, will not 
contribute significantly to nonattainment of the 2010 SO2 
NAAQS in any other state.
    The second facility contributing 60 percent of statewide 
SO2 emissions in 2014 is the Reid Gardner Generating Station 
that ceased operation in 2017. Consequently, this facility does not 
warrant further investigation with respect to SO2 emissions 
sources that

[[Page 17816]]

might significantly contribute to nonattainment in neighboring 
states.\32\
---------------------------------------------------------------------------

    \32\ As discussed in the EPA's rescission of regional haze 
federal implementation plan for the Reid Gardner Generating Station, 
three of the Reid Gardener Generating Station's coal-fired boilers 
ceased operation in 2014 and the fourth ceased operation in 2017. 
See 83 FR 24952, May 31, 2018.
---------------------------------------------------------------------------

    Table 4 below shows all other Nevada sources that generated more 
than 50 tpy of SO2 emissions in 2017 located within 50 km of 
the state border, including Nevada's second largest active source of 
SO2 emissions, the McCarran Airport. Table 4 also lists the 
nearest out-of-state neighboring sources emitting above 50 tpy of 
SO2 because elevated levels of SO2, to which 
SO2 emitted in Nevada may have a downwind impact, are most 
likely to be found near such sources.\33\ As shown in Table 4, the 
shortest distance between a Nevada source and a neighboring state 
source, with both emitting more than 50 tpy of SO2, is 167 
km. Furthermore, neighboring states have no sources of SO2 
emissions greater than 50 tpy located within 50 km of the Nevada 
border. Given the localized range of potential 1-hour SO2 
impacts, the data indicate that there are no additional locations in 
neighboring states that would warrant further investigation with 
respect to individual Nevada SO2 emissions sources that 
might contribute to nonattainment of the 2010 SO2 NAAQS.
---------------------------------------------------------------------------

    \33\ Table 4 contains more recent data than Table 3 because the 
EPA has only released facility reported point source data from the 
2017 NEI.

   Table 4--Nevada Sources With SO2 Emissions Greater than 50 tons in 2017 Within 50 km of a Neighboring State
----------------------------------------------------------------------------------------------------------------
                                                                   Distance to
                                                                   the closest     Name of the      Neighboring
                                    2017          Distance to      neighboring       closest         state SO2
        Nevada source           Emissions \a\       border         SO2 source    neighboring SO2    source 2017
                                   (tons)                         more than 50     source more       emissions
                                                                    tpy (km)       than 50 tpy        (tons)
----------------------------------------------------------------------------------------------------------------
McCarran International                    467  37 km (AZ)......             178  Lhoist North              1,678
 Airport, Las Vegas.                                                              America (NA),
                                                                                  Chemical Lime
                                                                                  Nelson Plant.
Republic Services Sunrise                 191  23 km (AZ)......             167  Lhoist NA,                1,678
 (Landfill), Las Vegas.                                                           Chemical Lime
                                                                                  Nelson Plant.
Lockwood Sanitary Landfill,               149  33 km (CA)......             193  Sacramento                  112
 Sparks.                                                                          International
                                                                                  Airport.
Lhoist NA and Granite                     140  32 km (AZ)......             171  Lhoist NA,                1,678
 Construction (Apex), Las                                                         Chemical Lime
 Vegas.                                                                           Nelson Plant.
EP Minerals, Clark Plant,                  82  45 km (CA)......             206  Sacramento                  112
 Clark.                                                                           International
                                                                                  Airport.
Reno-Tahoe International                   53  19 km (CA)......             181  Sacramento                 112
 Airport.                                                                         International
                                                                                  Airport.
----------------------------------------------------------------------------------------------------------------
\a\ Emissions are based on the 2017 facility reported NEI emissions data for point sources downloaded from
  https://www.epa.gov/air-emissions-inventories/2017-national-emissions-inventory-nei-data on October 9, 2019,
  and contained in the docket for this notice.

3. Conclusion
    In order to determine whether Nevada satisfied prong 1 for the 2010 
SO2 NAAQS, the EPA evaluated the State's 2013 SIP revision 
with respect to the following two factors: (1) SO2 ambient 
air quality in Nevada and neighboring states; and (2) SO2 
emissions sources in Nevada and neighboring states. For the first 
factor, we identified no violating monitors near the Nevada border, and 
the only violating monitors in neighboring states are well outside the 
range within which we might expect them to be significantly impacted by 
interstate transport of SO2 from Nevada. For the second 
factor, we identified no SO2 sources within 50 km of the 
Nevada border that are likely contributing to a violation of the 
standard in another state, and we conclude that it is unlikely that 
sources farther from the border are leading to violations. Therefore, 
based on the analysis provided by the State in its SIP submission and 
the factors discussed above, the EPA proposes to find that Nevada will 
not cause or contribute significantly to nonattainment of the 2010 1-
hour SO2 NAAQS in any other state.

D. The EPA's Evaluation of Prong 2--Interference With Maintenance

    Prong 2 of the good neighbor provision requires state plans to 
prohibit emissions that will interfere with maintenance of a NAAQS in 
another state. The EPA considers that reasonable criteria to ensure 
that sources or emissions activities originating within Nevada will not 
interfere with its neighboring states' ability to maintain the NAAQS 
involves a close examination of the following: (1) Air quality trends 
in Nevada and neighboring states; (2) SIP-approved state and county 
measures that limit existing and new facility emissions; and (3) 
ambient concentrations of SO2 in Nevada and neighboring 
states.
1. Air Quality Trends for Nevada and Neighboring States
    As shown in Table 5 below, the statewide Tier 1 SO2 
emissions trends for Nevada and neighboring states have substantially 
decreased over time.\34\ Since 2000, overall SO2 emissions 
have decreased by 89% in Nevada, 66% in Arizona, 82% in California, 77% 
in Idaho, 82% in Oregon, and 74% in Utah. The size and geographic scope 
of these reductions strongly suggest that the reductions are not 
transient effects from temporary causes and suggest that a trend of 
increasing emissions is unlikely to occur in these states.
---------------------------------------------------------------------------

    \34\ Tier 1 emissions trends data do not include event 
emissions, which include forest fires and prescribed or 
intentionally set fires.

                 Table 5--Tier 1 SO2 Emissions Trends for Nevada and Neighboring States (tpy) a
----------------------------------------------------------------------------------------------------------------
              State                    2000            2005            2010            2015            2017
----------------------------------------------------------------------------------------------------------------
Arizona.........................         116,207          89,198          71,706          43,623          39,243
California......................          80,698         155,677          35,769          22,956          22,835
Idaho...........................          23,015          22,962          11,718           5,396           5,386

[[Page 17817]]

 
Nevada..........................          61,689          71,609          14,065          10,352           6,947
Oregon..........................          53,237          24,916          19,625           9,500           8,182
Utah............................          56,039          51,945          28,932          19,865          14,832
----------------------------------------------------------------------------------------------------------------
\a\ Data downloaded from https://www.epa.gov/air-emissions-inventories/air-pollutant-emissions-trends-data
  (State Annual Average Emission Trend) and included in the docket for today's notice. See SO2 Trends Tier
  1.xlsx.

    Table 6 shows the emissions trend since 2008 for all Nevada 
facilities that emitted more than 100 tpy of SO2. While some 
facilities, such as McCarran International Airport, show an increasing 
trend, the increases are small relative to the decreases at the North 
Valmy Generating Station and Reid Gardner Generating Station, and the 
overall downward trend in SO2 emissions in Nevada is 
illustrated by the row showing total point source emissions.

       Table 6--SO2 Emission Trends for Nevada Facilities That Have Emitted More Than 50 tpy Since 2008 a
----------------------------------------------------------------------------------------------------------------
          Facility name               EIS ID           2008            2011            2014            2017
----------------------------------------------------------------------------------------------------------------
NV Energy, North Valmy                   7302011           8,130           3,550           7,430           1,588
 Generating Station.............
McCarran International (Airport)         9392311             264             272             265             467
EP Minerals LLC, Colado Plant...         6030011              72             140              26             250
Republic Services Sunrise.......         9398611             163             197             209             191
Newmont Nevada Energy LLC, TS           12758911             364             250             234             152
 Power Plant....................
Lockwood Sanitary Landfill......         6030711               0              69              43             149
Lhoist North America and Granite         8210711             180             229             152             140
 Const. (Apex)..................
Newmont Mining Corp. Twin Creek          8178211              38               6               6             102
 Mine...........................
Nevada Cement, Fernley Plant....         8179811             282             118             126              90
Barrick Goldstrike Mines Inc.,           8177811              40              28              50              70
 GoldStrike Mine................
Reno Tahoe Airport..............         9376411            NA b              50              25              53
Graymont Western U.S. Pilot Peak         6673911              28              30              23              15
 Plant..........................
(Newmont) Gold Quarry...........         8210011              56              59              15              12
Foreland Refining (Eagle                 8179311              76              85              77               7
 Springs).......................
NV Energy Reid Gardner                   6815611             941           1,423           2,506             c 0
 Generating Station.............
Halliburton Energy Services              7200311             194               3               1               0
 Dunphy Plant & Crusher.........
All Nevada Point Source                       NA          11,598           6,901          11,594           3,710
 Emissions......................
All Nevada Emissions............              NA          20,951          13,578          16,175              NA
----------------------------------------------------------------------------------------------------------------
\a\ Data from the NEI (files 2008 NEI V3, 2011 NEI V2, 2014 NEI V2, and 2017Oct) downloaded to 2002-2017 NV
  Facility Data.xlsx.
\b\ NA--Not available.
\c\ No emissions were reported to the EPA's NEI in 2017 for the Reid Gardner Generating Station, but emissions
  of 168 tons in 2017 were reported to the EPA's Clean Air Markets program (data query on 11/18/2019).

    While these trends do not by themselves demonstrate that Nevada and 
neighboring states will not have issues maintaining the 2010 
SO2 NAAQS, when considered alongside low ambient 
concentrations in Nevada and neighboring states, as illustrated in 
Table 1, they provide further evidence that emissions of SO2 
from Nevada are unlikely to interfere with maintenance of the 
SO2 NAAQS in other states.
2. Nevada's Air Quality Rules
    The 2013 Nevada SIP submittal identifies many rules for controlling 
current and future SO2 or sulfur oxides (SOX) 
emissions.\35\ The rules identified by the NDEP primarily regulate fuel 
combustion from large power plants as well as smaller stationary 
combustion sources (e.g., portable generators). The NDEP retains 
authority over facilities that generate electricity by using steam 
produced from fossil fuels, even if located within Clark or Washoe 
counties. Emissions limits for SOX are set by Nevada 
Administrative Code (NAC) 445B.22095 and NAC 445.22096. NAC 445B.22095 
identifies factors considered in determining best available control 
technology (BACT) for major sources, and NAC 445B.22096 provides 
numeric emissions limits for specific sources where BACT has been 
established for the Nevada Energy Tracy Generating Station and the 
Nevada Energy Fort Churchill Generating Station.\36\ NAC 445B.22047 and 
Article 8.2.1 limit SO2 emissions from the combustion of 
fuel based on the heat input of the fuel in British Thermal Units 
(BTUs). NAC 445B.2205 limits SO2 emissions from other 
processes. Nevada also identified many supporting regulations, such as 
rules covering definitions, calculations, and exemptions, including the 
following: NAC 445B.22043 (``Sulfur emissions: Calculation of total 
feed sulfur''); NAC 445B.22083 (``Construction, major modification or 
relocation of plants to generate electricity using steam produced by 
burning fossil fuels''); NAC 445B.308 (``Prerequisites and conditions 
for issuance of certain operating permits; compliance with applicable 
state implementation plan''); NAC 445B.310 (``Environmental evaluation: 
Applicable sources and other subjects; exemption''); and NAC 445B.311 
(``Environmental evaluation: Contents; and consideration of good 
engineering practice stack height'').\37\
---------------------------------------------------------------------------

    \35\ SOX is a group of gases that includes 
SO2 and other less common oxides of sulfur in the 
atmosphere, see https://www.epa.gov/so2-pollution.
    \36\ This rule also discusses the Mojave Generation Station, 
which has been demolished (82 FR 48769, October 20, 2017), and the 
closed Reid Garner Generating Station.
    \37\ The NDEP implements its minor source (25 tpy) permitting 
through Nevada Revised Statutes 445B.310, 311 and NAC 308. See EPA's 
Technical Support Document, Evaluation of the Nevada Infrastructure 
SIP for 2008 Ozone, 2010 NO2 and 2010 SO2, 19. 
The NDEP implements its major source permitting through a prevention 
of significant deterioration federal implementation plan.

---------------------------------------------------------------------------

[[Page 17818]]

    Clark County broadly identified permitting rules limiting current 
and future SO2 and hydrogen sulfide emissions. More 
specifically, Clark County permits require the following: Reasonably 
available control technology (RACT) for minor sources (25 tpy for 
SO2) and existing sources with significant emissions 
increases, if a RACT determination has been made; \38\ BACT for major 
new sources and existing sources proposing significant increases in 
attainment areas; \39\ and a limit on maximum increment increases of 
SO2 for areas with a regional haze designation of Class I, 
Class II, or Class III.\40\
---------------------------------------------------------------------------

    \38\ See Air Quality Regulation (AQR) 12.1.3.6(c)(1) and (2).
    \39\ See AQR 12.2.9.1 and 12.2.9.2.
    \40\ Microgram per meter cubed SO2 limits for annual 
mean, 24-hour maximum, and 3-hour maximum, per AQR 12.2.3. The 
discussion of Element A in the EPA's Technical Support Document, 
Evaluation of the Nevada Infrastructure SIP for 2008 Ozone, 2010 
NO2, and 2010 SO2 contains regulatory 
citations for Clark County rules, with the exception of maximum 
increment increases that can be found in the Clark County 
Regulations at AQR 12.2.3. and the variance procedure at 12.2.15.4.
---------------------------------------------------------------------------

    For limiting SO2 emissions, Washoe County identified 
rules that control trace quantities of SOX emissions from 
the storage of petroleum products, gasoline loading, gasoline 
unloading, and the use of organic solvents.\41\ An additional SIP-
approved Washoe County regulation that controls SOX is 
Section 040.060 (``Sulfur Content of Fuel''). It limits the sulfur 
content to 0.7% by weight for solid fuels and 1.0% for liquid fuels 
burned at less than 250 million BTUs of heat input. For fuels burned at 
more than 250 million BTUs of heat input per hour, Section 040.060 
provides a calculation that sets a maximum quantity of sulfur (in 
pounds per hour).
---------------------------------------------------------------------------

    \41\ Washoe Rules 040.070, 040.075, 040.080, and 040.085.
---------------------------------------------------------------------------

    In conclusion, for interstate transport prong 2, we reviewed 
SO2 emissions trends in Nevada and neighboring states, 
Nevada's SIP-approved rules regulating SO2 and 
SOX, and the technical information related to SO2 
ambient air quality and SO2 emissions for interstate 
transport prong 1, as discussed above. Based on (1) the downward trend 
in SO2 emissions in Nevada and neighboring states; (2) SIP-
approved State and local measures that limit existing and new facility 
emissions; and (3) the low ambient concentrations of SO2 in 
Nevada and neighboring states, we propose to determine that the 2013 
Nevada SIP revision demonstrates that SO2 emissions in the 
State will not interfere with maintenance of the 2010 SO2 
NAAQS in any other state, per the requirements of prong 2 of CAA 
section 110(a)(2)(D)(i)(I).

III. Proposed Action

    In light of the above analysis, the EPA is proposing to approve 
Nevada's infrastructure submittal for the 2010 SO2 NAAQS as 
it pertains to section 110(a)(2)(D)(i)(I) of the CAA.
    We will accept comments from the public on these proposals for the 
next 30 days and plan to follow with a final action. The deadline and 
instructions for submission of comments are provided in the DATE and 
ADDRESSES sections at the beginning of this proposed rule.

IV. Statutory and Executive Order Reviews

    Under the Clean Air Act, the Administrator is required to approve a 
SIP submission that complies with the provisions of the Act and 
applicable federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a). 
Thus, in reviewing SIP submissions, the EPA's role is to approve state 
choices, provided that they meet the criteria of the Clean Air Act. 
Accordingly, this proposed action merely proposes to approve state law 
as meeting federal requirements and does not impose additional 
requirements beyond those imposed by state law. For that reason, this 
proposed action:
     Is not a ``significant regulatory action'' subject to 
review by the Office of Management and Budget under Executive Orders 
12866 (58 FR 51735, October 4, 1993) and 13563 (76 FR 3821, January 21, 
2011);
     Is not an Executive Order 13771 (82 FR 9339, February 2, 
2017) regulatory action because SIP approvals are exempted under 
Executive Order 12866;
     Does not impose an information collection burden under the 
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
     Is certified as not having a significant economic impact 
on a substantial number of small entities under the Regulatory 
Flexibility Act (5 U.S.C. 601 et seq.);
     Does not contain any unfunded mandate or significantly or 
uniquely affect small governments, as described in the Unfunded 
Mandates Reform Act of 1995 (Pub. L. 104-4);
     Does not have Federalism implications as specified in 
Executive Order 13132 (64 FR 43255, August 10, 1999);
     Is not an economically significant regulatory action based 
on health or safety risks subject to Executive Order 13045 (62 FR 
19885, April 23, 1997);
     Is not a significant regulatory action subject to 
Executive Order 13211 (66 FR 28355, May 22, 2001);
     Is not subject to requirements of Section 12(d) of the 
National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272 
note) because application of those requirements would be inconsistent 
with the Clean Air Act; and
     Does not provide the EPA with the discretionary authority 
to address disproportionate human health or environmental effects with 
practical, appropriate, and legally permissible methods under Executive 
Order 12898 (59 FR 7629, February 16, 1994).
    In addition, the SIP is not approved to apply on any Indian 
reservation land or in any other area where the EPA or an Indian tribe 
has demonstrated that a tribe has jurisdiction. In those areas of 
Indian country, the rule does not have tribal implications and will not 
impose substantial direct costs on tribal governments or preempt tribal 
law as specified by Executive Order 13175 (65 FR 67249, November 9, 
2000).

List of Subjects in 40 CFR Part 52

    Environmental protection, Air pollution control, Incorporation by 
reference, Intergovernmental relations, Sulfur oxides.

    Authority: 42 U.S.C. 7401 et seq.

    Dated: March 20, 2020.
John Busterud,
Regional Administrator, Region IX.
[FR Doc. 2020-06348 Filed 3-30-20; 8:45 am]
 BILLING CODE 6560-50-P


