Document ID: EPA-R09-OAR-2022-0955-0001
Agency: epa
Document Type: Proposed Rule
Title: Approval of Implementation Plans for Air Quality Planning Purposes; State of Nevada; Clark County Second 10-Year Maintenance Plan for the 1997 8-Hour Ozone Standard
Posted Date: 2023-12-21T05:00Z

[Federal Register Volume 88, Number 244 (Thursday, December 21, 2023)]
[Proposed Rules]
[Pages 88300-88308]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-27874]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R09-OAR-2022-0955; FRL-10549-01-R9]

Approval of Implementation Plans for Air Quality Planning 
Purposes; State of Nevada; Clark County Second 10-Year Maintenance Plan 
for the 1997 8-Hour Ozone Standard

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing to 
approve, as a revision of the Nevada state implementation plan (SIP), 
the State's second 10-year plan for maintaining the 1997 8-hour ozone 
standard in Clark County (``Clark County Second Maintenance Plan'' or 
``Plan''). The Clark County Second Maintenance Plan includes, among 
other elements, a base year emissions inventory, a maintenance 
demonstration, contingency provisions, and motor vehicle emissions 
budgets for use in transportation conformity determinations to ensure 
the continued maintenance of the 1997 National Ambient Air Quality 
Standards for ozone (``1997 ozone NAAQS'' or ``1997 8-hour ozone 
standard''). With this proposed rulemaking, the EPA is initiating the 
adequacy process for the 2017, 2023, and 2033 motor vehicle emissions 
budgets. The EPA is proposing these actions because the SIP revision 
meets the applicable statutory and regulatory requirements for such 
plans and motor vehicle emissions budgets.

DATES: Comments must be received on or before January 22, 2024.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R09-
OAR-2022-0955, at https://www.regulations.gov. For comments submitted 
at Regulations.gov, follow the online instructions for submitting 
comments. Once submitted, comments cannot be edited or removed from 
Regulations.gov. 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 https://www.epa.gov/dockets/commenting-epa-dockets. If you need assistance in a 
language other than English or if you are a person with a disability 
who needs a reasonable accommodation at no cost to you, please contact 
the person identified in the FOR FURTHER INFORMATION CONTACT section.

FOR FURTHER INFORMATION CONTACT: Andrew Ledezma, EPA Region IX, 75 
Hawthorne St., San Francisco, CA 94105. By phone: (415) 972-3985 or by 
email at [email protected].

SUPPLEMENTARY INFORMATION: Throughout this document, ``we,'' ``us,'' 
and ``our'' refer to the EPA.

Table of Contents

I. Summary of Proposed Action
II. Background
III. Second 10-Year Maintenance Plan Submittal and Procedural 
Requirements
IV. Requirements for Second 10-Year Maintenance Plans
V. Evaluation of the Clark County Second Maintenance Plan
    A. Monitoring Network Requirements
    B. Attainment Inventory
    C. Maintenance Demonstration
    D. Verification of Continued Attainment
    E. Contingency Provisions
    F. Motor Vehicle Emissions Budgets for Transportation Conformity
VI. Environmental Justice Considerations
VII. Proposed Action and Request for Public Comment
VIII. Statutory and Executive Order Reviews

I. Summary of Proposed Action

    Under Clean Air Act (CAA or ``the Act'') section 110(k)(3), the EPA 
is proposing to approve two submittals from the Nevada Division of 
Environmental Protection (NDEP) as a revision to the Nevada SIP: the 
Clark County Second Maintenance Plan dated December 21, 2021, and a 
supplement to the Clark County Second Maintenance Plan (``Contingency 
Measure Revision'') dated August 16, 2023. In this action, we refer to 
the Clark County Second Maintenance Plan and the Contingency Measure 
Revision collectively as the ``Clark County Second Maintenance Plan 
submittal.''
    The EPA is proposing to find that the maintenance demonstration, 
showing how the area will continue to attain the 1997 8-hour ozone 
NAAQS for 10 additional years beyond the approval the State's first 10-
year plan for maintaining the 1997 8-hour ozone standard in Clark 
County (``Clark County First Maintenance Plan'' or ``first maintenance 
plan'') (i.e., through 2033), and the contingency provisions, 
describing the actions that Clark County will take in the event of a 
future monitored violation, meet all applicable requirements for 
maintenance plans and related contingency provisions in CAA section 
175A. The EPA is also proposing to approve the motor vehicle emissions 
budgets (MVEBs or ``budgets'') in the Clark County Second Maintenance 
Plan because we find they meet the applicable transportation conformity 
requirements under 40 CFR 93.118(e).

II. Background

    Sections 108 and 109 of the CAA govern the establishment, review, 
and revision, as appropriate, of the NAAQS to protect public health and 
welfare. The CAA requires the EPA to periodically review the air 
quality criteria, the science upon which the standards are based, and 
the standards themselves. Ground-level ozone is one of the criteria 
pollutants regulated under the NAAQS.
    Ground-level ozone is generally not emitted directly by sources. 
Rather, directly emitted oxides of nitrogen (NOX) and 
volatile organic compounds (VOC) react in the presence of sunlight to 
form ground-level ozone, as a secondary pollutant, along with other 
secondary compounds. NOX and VOC are ``ozone precursors.'' 
Reduction of peak ground-level ozone concentrations is typically 
achieved through controlling VOC and NOX emissions.
    Scientific evidence indicates that adverse public health effects 
occur following exposure to ozone, particularly in children and adults 
with lung disease. Breathing air containing ozone can reduce lung 
function and inflame airways, which can increase respiratory symptoms 
and aggravate asthma or other lung diseases.\1\
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    \1\ ``Fact Sheet--2008 Final Revisions to the National Ambient 
Air Quality Standards for Ozone,'' dated March 2008.

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[[Page 88301]]

    In 1997, the EPA revised the NAAQS for ozone, setting it at 0.08 
parts per million (ppm) averaged over an 8-hour time frame.\2\ The EPA 
set the 1997 8- hour ozone standard based on scientific evidence 
demonstrating that ozone causes adverse health effects at lower ozone 
concentrations and over longer periods of time, than was understood 
when the pre-existing 1-hour ozone standard was set. The EPA determined 
that the 1997 8-hour ozone NAAQS would be more protective of human 
health, especially for children and adults who are active outdoors, and 
individuals with a pre-existing respiratory disease, such as asthma.\3\
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    \2\ 62 FR 38856 (July 18, 1997).
    \3\ On March 27, 2008 (73 FR 16436), the EPA promulgated a 
revised 8-hour ozone standard of 0.075 ppm (the 2008 8-hour ozone 
standard), and on May 21, 2012, the EPA designated the entire state 
of Nevada unclassifiable/attainment for the 2008 8-hour ozone 
standard (77 FR 30088). This rulemaking relates only to the 1997 8-
hour ozone standard and does not relate to the 2008 8-hour ozone 
standard.
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    In 2004, the EPA designated areas of the country with respect to 
the 1997 8-hour ozone NAAQS.\4\ Under the EPA's ``Phase 1'' 
implementation rule for the 1997 8-hour ozone standard \5\ an area was 
classified under subpart 2 based on its 8-hour ozone design value 
(i.e., the 3-year average annual fourth-highest daily maximum 8-hour 
average ozone concentration at the worst-case monitoring site in the 
area or in its immediate downwind environs), if it had a 1-hour ozone 
design value \6\ at the time of designation at or above 0.121 ppm. All 
other areas were covered under subpart 1 based on their 8-hour ozone 
design values.\7\ Clark County was designated as a subpart 1 ozone 
nonattainment area by the EPA on April 30, 2004, based on air quality 
monitoring data from 2001-2003. The designation became effective on 
June 15, 2004. On September 17, 2004, the EPA reduced the geographic 
extent of the ozone nonattainment area to encompass a portion, but not 
all, of Clark County.\8\
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    \4\ 69 FR 23858 (April 30, 2004).
    \5\ 69 FR 23951, (April 30, 2004).
    \6\ The design value for the 1-hour ozone standard is the 
fourth-highest daily maximum 1-hour ozone concentration over a 
three-year period at the worst-case monitoring site in the area.
    \7\ 69 FR 23951. The design value for the 8-hour standard is the 
three-year average of the annual fourth-highest daily maximum 8-hour 
ozone concentration at the worst-case monitoring site in the area.
    \8\ 69 FR 55956 (September 17, 2004), 70 FR 71612 (November 29, 
2005), and 40 CFR 81.329. The boundaries of the Clark County ozone 
nonattainment area are defined in 40 CFR 81.329. Specifically, the 
area is defined as: ``That portion of Clark County that lies in 
hydrographic areas 164A, 164B, 165, 166, 167, 212, 213, 214, 216, 
217, and 218 but excluding the Moapa River Indian Reservation and 
the Fort Mojave Indian Reservation.'' The area includes a 
significant portion of the unincorporated portions of central and 
southern Clark County, as well as the cities of Las Vegas, 
Henderson, North Las Vegas, and Boulder City.
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    In South Coast Air Quality Management Dist. v. EPA \9\ the U.S. 
Court of Appeals for the District of Columbia Circuit (D.C. Circuit, or 
``Court'') vacated the EPA's Phase 1 implementation rule for the 1997 
8-hour ozone standard.\10\ In response to several petitions for 
rehearing, the D.C. Circuit clarified that the Phase 1 rule was vacated 
only for those parts of the rule that had been successfully 
challenged.\11\ The decision left intact the Court's rejection of the 
EPA's reasons for implementing the 8-hour ozone standard in certain 
nonattainment areas under subpart 1 in lieu of subpart 2 of the CAA.
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    \9\ 472 F.3d 882 (D.C. Cir. 2007).
    \10\ 69 FR 23951.
    \11\ 472 F.3d 882 (D.C. Cir. 2007).
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    On May 14, 2012, in response to the Court's vacatur of the 
provision of the Phase 1 rule for the 1997 8-hour ozone standard that 
placed certain nonattainment areas, including Clark County solely under 
subpart 1, the EPA classified Clark County as a marginal ozone 
nonattainment area under subpart 2 of the CAA.\12\
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    \12\ 77 FR 28424.
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    On March 29, 2011, the EPA determined that the Clark County 8-hour 
ozone nonattainment area had attained the 1997 8-hour ozone NAAQS, 
based on complete, quality-assured, and certified ambient air 
monitoring data that showed the area monitored attainment of the 1997 
8-hour ozone NAAQS for the 2007-2009 monitoring period.\13\
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    \13\ 76 FR 17343.
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    On April 11, 2011, NDEP submitted the Clark County First 
Maintenance Plan and requested that the EPA redesignate the Clark 
County 8-hour ozone nonattainment area to attainment for the 1997 8-
hour ozone standard. On January 8, 2013, the EPA approved the Clark 
County First Maintenance Plan, and redesignated the area from 
nonattainment to attainment of the 1997 8-hour ozone NAAQS.\14\
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    \14\ 78 FR 1149.
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    On October 31, 2018, NDEP submitted a Revision to Motor Vehicle 
Emissions Budgets in Ozone Redesignation Request and Maintenance Plan 
(``2018 Ozone Maintenance Plan Revision''). The 2018 Ozone Maintenance 
Plan Revision updated elements of the Clark County First Maintenance 
Plan, including the attainment inventory, the maintenance 
demonstration, and the budgets. The 2018 Ozone Maintenance Plan 
Revision established ozone season budgets of 52.96 and 86.74 tons per 
day (tpd) for VOC and NOX, respectively, for 2022 so that 
the area would have updated budgets available to use for transportation 
conformity determinations with respect to the 2015 National Ambient Air 
Quality Standards for ozone (``2015 ozone NAAQS'').\15\ On August 27, 
2019, the EPA conditionally approved the 2018 Ozone Maintenance Plan 
revisions, based on commitments to submit an additional SIP revision to 
reduce the safety margin allocations for the budgets within one year of 
the final conditional approval.\16\
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    \15\ 84 FR 33038 (July 11, 2019).
    \16\ 84 FR 44699.
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    On September 30, 2020, NDEP submitted an additional Revision to 
Motor Vehicle Emissions Budgets for the 1997 ozone NAAQS, Clark County, 
Nevada (``2020 Ozone Maintenance Plan Revision''). The 2020 Ozone 
Maintenance Plan Revision was prepared in response to the EPA's 
conditional approval of the 2018 Ozone Maintenance Plan Revision. The 
2020 Ozone Maintenance Plan Revision revised certain budgets from the 
2018 Ozone Maintenance Plan Revision to prevent interference with 
Reasonable Further Progress (RFP) or attainment of the 2008 and 2015 
ozone NAAQS. The 2020 Ozone Maintenance Plan Revision established 
budgets of 23.92 and 32.16 tons per average summer day \17\ for VOC and 
NOX, respectively, for 2022. On October 28, 2021, with the 
submittal of the 2020 Ozone Maintenance Plan Revision, the EPA approved 
the updates to the attainment inventory, the maintenance demonstration, 
and the budgets to the Clark County First Maintenance Plan.\18\
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    \17\ According to ``Emissions Inventory Guidance for 
Implementation of Ozone and Particulate Matter National Ambient Air 
Quality Standards (NAAQS) and Regional Haze Regulations,'' dated May 
2017, terminology used has changed from ``summer day'' emissions to 
``ozone season'' emissions. However, ``average summer day'' 
emissions are used in this instance to stay consistent between motor 
vehicle emissions budgets of different ozone standards.
    \18\ 86 FR 59643.
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    On January 24, 2022, NDEP submitted the Clark County Second 
Maintenance Plan showing how the area will continue to attain the 1997 
8-hour ozone national ambient air quality standard (NAAQS) for 10 
additional years beyond the approval the State's first 10-year plan.
    Lastly, on August 16, 2023, NDEP submitted the Contingency Measure 
Revision, which revised the contingency measure section of the Clark 
County Second Maintenance Plan. In this action, we are proposing action 
on the

[[Page 88302]]

NDEP's Clark County Second Maintenance Plan submittal.

III. Second 10-Year Maintenance Plan Submittal and Procedural 
Requirements

    CAA section 110(a)(1) and (2) and section 110(1) require states to 
provide reasonable notice and public hearing prior to adoption of SIP 
revisions. In this action, we are proposing action on NDEP's January 
24, 2022, submittal of the Clark County Ozone Second Maintenance Plan, 
and NDEP's August 16, 2023, submittal of the Contingency Measure 
Revision as a revision to the Nevada SIP, collectively referred to as 
the Clark County Second Maintenance Plan submittal.
    Following a 30-day public comment period, the Clark County Second 
Maintenance Plan was adopted by the Clark County Board of 
Commissioners, submitted to NDEP, and submitted to the EPA. Appendix B 
of the Clark County Second Maintenance Plan documents the public review 
process followed by Clark County in adopting the plan prior to 
transmittal to NDEP for subsequent submittal to the EPA as a revision 
to the Nevada SIP. The documentation in appendix B provides evidence 
that reasonable notice of a public hearing was provided to the public 
and that a public hearing was conducted prior to adoption. 
Specifically, notice of the availability of, and opening of a 30-day 
comment period on, the draft Clark County Second Maintenance Plan was 
published on October 14, 2021, on the Clark County Department of 
Environment and Sustainability (DES) website, the DES official Facebook 
page, and the DES official Twitter. No comments were submitted.
    On December 7, 2021, the Clark County Board of Commissioners set a 
public hearing for December 21, 2021, to consider and approve the Clark 
County Second Maintenance Plan. The announcement of the public hearing 
was subsequently published on the County's web page. On December 21, 
2021, the Clark County Board of Commissioners adopted the Clark County 
Second Maintenance Plan at the close of the public hearing. Following 
adoption, Clark County DES forwarded the plan to NDEP, the Governor of 
Nevada's designee for SIP matters, and NDEP then submitted the plan as 
a revision to the Nevada SIP to the EPA for approval on January 24, 
2022.
    Appendix A of the Contingency Measure Revision documents the board 
approval process followed by Clark County in adopting the plan prior to 
transmittal to NDEP for subsequent submittal to the EPA as a revision 
to the Nevada SIP. On July 18, 2023, the Clark County Board of 
Commissioners put the Contingency Measure Revision up for public notice 
and adopted the Contingency Measure Revision at the close of the public 
hearing. Following adoption, Clark County DES forwarded the plan to 
NDEP and NDEP then submitted the plan, as a revision to the Nevada SIP, 
to the EPA for approval on August 16, 2023.
    Based on the documentation contained in appendix B of the Plan and 
appendix A of the Contingency Measure Revision, we find that the Clark 
County Second Maintenance Plan submittal satisfies the procedural 
requirements of section 110(l) of the Act.

IV. Requirements for Second 10-Year Maintenance Plans

    Section 175A of the CAA provides the general framework for a 
maintenance plan. The initial 10-year maintenance plan must provide for 
maintenance of the NAAQS for at least 10 years after redesignation, 
including any additional control measures necessary to ensure such 
maintenance. In addition, maintenance plans are to contain contingency 
provisions necessary to ensure the prompt correction of a violation of 
the NAAQS that occurs after redesignation. The contingency measures 
must include, at a minimum, a requirement that the state will implement 
all control measures contained in the nonattainment SIP prior to 
redesignation. Beyond these provisions, section 175A of the CAA does 
not define the content of a second 10-year maintenance plan.
    The primary guidance on maintenance plans and redesignation 
requests is a September 4, 1992, memorandum from John Calcagni, titled 
``Procedures for Processing Requests to Redesignate Areas to 
Attainment'' (Calcagni Memo).\19\ The Calcagni Memo outlines the key 
elements of a maintenance plan, which include verification of continued 
attainment, monitoring network requirements, attainment emissions 
inventory, maintenance demonstration, and a contingency plan. We 
evaluate the Second 10-Year Maintenance Plan based on the satisfactory 
fulfillment of these and all relevant procedural requirements of the 
CAA.
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    \19\ Memorandum dated September 4, 1992, from John Calcagni, 
Director, EPA Air Quality Management Division, to Regional Office 
Air Division Directors, Subject: Procedures for Processing Requests 
to Redesignate Areas to Attainment.
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    CAA section 175A(b) requires states to submit an additional SIP 
revision (Second 10-Year Maintenance Plan) to maintain the NAAQS for an 
additional 10 years after the expiration of the 10-year period covered 
by the initial maintenance plan approved in connection with the 
redesignation of the area from nonattainment to attainment. The 
revision is submitted eight years after the original redesignation 
request and maintenance plan have been approved. The deadline to submit 
Clark County's Second Maintenance Plan was January 8, 2021. On January 
24, 2022, NDEP submitted the Clark County Second Maintenance Plan, to 
meet the requirement for the subsequent maintenance plan under CAA 
section 175A(b). The Clark County Second Maintenance Plan is intended 
to provide for continued maintenance of the 1997 ozone NAAQS for the 
10-year period following the end of the first 10-year period, i.e., 
from 2024 through 2033.

V. Evaluation of the Clark County Second Maintenance Plan

    Section 175A of the CAA sets forth the elements of a maintenance 
plan. We interpret this section of the Act to require, in general, the 
following core elements: attainment inventory, maintenance 
demonstration, monitoring network, verification of continued 
attainment, and contingency plan.\20\ Under CAA section 175A, a 
maintenance plan must demonstrate continued attainment of the 
applicable NAAQS for at least ten years after the EPA approves a 
redesignation to attainment. Eight years after redesignation, the State 
must submit a revised maintenance plan that demonstrates continued 
attainment for the subsequent ten-year period following the initial 
ten-year maintenance period. To address the possibility of future NAAQS 
violations, the maintenance plan must contain such contingency 
provisions that the EPA deems necessary to promptly correct any 
violation of the NAAQS that occurs after redesignation of the area. 
Based on our review and evaluation of the plan, as detailed below, we 
are proposing to approve the Clark County Second Maintenance Plan 
submittal because we believe that it meets the requirements of CAA 
section 175A.
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    \20\ Calcagni Memo, 8-13.
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A. Monitoring Network Requirements

    Continued ambient monitoring of an area is generally required over 
the maintenance period. Clark County DES currently operates ozone 
monitors at thirteen sites within the Clark County 8-hour ozone 
maintenance area.

[[Page 88303]]

    In the Clark County Second Maintenance Plan,\21\ Clark County DES 
indicates its intention to continue operation of an air quality 
monitoring network to verify continued attainment of the 1997 8-hour 
ozone NAAQS.\22\ The Clark County Second Maintenance Plan also notes 
that Clark County DES's State and Local Air Monitoring Stations (SLAMS) 
air quality monitoring network (which includes ambient ozone 
monitoring) will be reviewed annually pursuant to 40 CFR 58.20(d) to 
determine whether the system continues to meet the applicable 
monitoring objectives.\23\ We approved Clark County's SLAMS air quality 
network in their Annual Monitoring Network Plan for year 2020 on 
October 28, 2020, prior to Clark County's submittal of the Clark County 
Second Maintenance Plan. We find the County's commitment for continued 
ambient ozone monitoring as set forth in the Clark County Second 
Maintenance Plan to be acceptable.
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    \21\ Clark County Second Maintenance Plan, 20-23.
    \22\ Although the Clark County Second Maintenance Plan is not 
explicit in this regard, we presume that Clark County DES's 
intention to continue operation of a monitoring network means that 
the agency intends to do so consistent with the EPA's monitoring 
requirements in 40 CFR part 58 (``Ambient Air Quality 
Surveillance'').
    \23\ The EPA's requirements for annual review of monitoring 
networks are no longer codified at 40 CFR 58.20(d) but are now found 
at 40 CFR 58.10.
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B. Attainment Inventory

    For maintenance plans, a state should develop a comprehensive and 
accurate inventory of actual emissions for an attainment year which 
identifies the level of emissions in the area which is sufficient to 
maintain the NAAQS. The inventory should be developed consistent with 
the EPA's most recent guidance. For ozone, the inventory should be 
based on typical ozone season day emissions of NOX and VOC.
    In the Clark County First Maintenance Plan, Clark County DES used 
2008 for the attainment year inventory, because 2008 was one of the 
years in the 2007-2009 three-year period when the area first attained 
the 1997 ozone NAAQS.\24\ Clark County DES continued to monitor 
attainment of the 1997 ozone NAAQS in 2017. Therefore, the emissions 
inventory from 2017 represents emissions levels consistent with 
continued attainment (i.e., maintenance) of the NAAQS. Thus, Clark 
County DES selected 2017 as the year for the attainment inventory in 
the Clark County Second Maintenance Plan. We consider the selection of 
the 2017 base year inventory to be appropriate given that it was the 
most recent emissions inventory associated with the reporting schedule 
required under the Air Emissions Reporting Requirements rule at the 
time of Plan drafting.
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    \24\ 76 FR 17343 (Apr. 29, 2011).
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    Table 1 presents the VOC and NOX emissions estimates 
contained in the Clark County Second Maintenance Plan for 2017 and 
presents the Plan's projected emissions inventories of ozone precursors 
in an interim year (2023) and the maintenance plan's horizon year 
(2033).\25\
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    \25\ The emissions inventories reflect county-wide emissions 
which include both the nonattainment area portion of the county and 
the portion of the county designated as ``unclassifiable/
attainment'' for the 1997 8-hour ozone NAAQS. County-wide emissions 
are acceptable to characterize emissions within the Clark County 
ozone nonattainment area because over 95% of the population of the 
county resides in the nonattainment area.

                           Table 1--Clark County 2017 and Projected 2023 and 2033 VOC and NOX Emissions Total Daily Emissions
                                                       [Tpd, average summer ozone season weekday]
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                                                                       2017                            2023                            2033
                    Emissions source                     -----------------------------------------------------------------------------------------------
                                                                VOC             NOX             VOC             NOX             VOC             NOX
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Point Source............................................            2.95           12.34            2.62           11.41            2.63           11.33
Nonpoint Source.........................................           64.69            4.69           67.83            5.03           71.31            4.78
Mobile--On-road.........................................           26.27           42.20           17.85           22.22           11.50           11.13
Mobile--Nonroad.........................................           28.86           37.45           27.24           23.27           27.82           15.37
Airports................................................            1.96           11.90            2.64           15.53            3.05           19.77
Locomotives.............................................            0.07            1.42            0.05            1.21            0.04            0.96
Emission Reduction Bank.................................            0.00            0.00            0.43           22.23            0.43           22.23
Biogenic................................................          362.61            2.43          362.61            2.43          362.61            2.43
                                                         -----------------------------------------------------------------------------------------------
    Total...............................................          487.41          112.43          481.27          103.33          479.39           88.00
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Source: Clark County Second Maintenance Plan, 17, Tables 2-4 and 2-5.
\a\ Emissions associated with the proposed Department of Air Force (DAF) Training Project is included in Airport emissions projections for the 2023 and
  2033 emissions projections for general conformity purposes. Emissions associated with the proposed Southern Nevada Supplemental Airport and proposed
  Sloan Regional Heliport are included for the 2033 emissions projection for general conformity purposes.

    The data shown in Table 1 in this document is based on the 2017 
National Emissions Inventory (NEI).\26\ The inventory addresses point 
sources,\27\ nonpoint sources,\28\ on-road mobile, non-road mobile, 
airports, locomotives, Emission Reduction Credits (ERCs),\29\ and 
biogenic \30\ sources. Appendix A to the Clark County Second 
Maintenance Plan contains source-specific descriptions of emissions 
calculation procedures and sources of input data.
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    \26\ The NEI is a comprehensive and detailed estimate of air 
emissions of criteria pollutants, criteria precursors, and hazardous 
air pollutants from air emissions sources. The NEI is released every 
three years based primarily upon data provided by State, Local, and 
Tribal air agencies for sources in their jurisdictions and 
supplemented by data developed by the EPA.
    \27\ The Clark County Second Maintenance Plan uses the term, 
``point sources,'' to refer to those stationary source facilities 
that are required to report their emissions to Clark County DES or 
NDEP.
    \28\ The Clark County Second Maintenance Plan uses the term, 
``nonpoint sources,'' to refer to those stationary and area sources 
that fall below point source reporting levels and that are too 
numerous or small to identify individually.
    \29\ The Clark County Second Maintenance Plan uses the term, 
``ERCs'' to refer to allowances earned through voluntary pollutant 
emission reductions such as equipment shutdowns or voluntarily 
installed controls.
    \30\ For the Clark County Second Maintenance Plan, ``biogenic 
sources'' include agricultural crops; lawn grass; forests that 
produce isoprene, monoterpene, and other VOC emissions; and soils 
that generate trace amounts of NOX.
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    Point sources are stationary sources that have a potential to emit 
(PTE) greater than 100 tons per year of NOX or VOC. Clark 
County DES adopted a lower threshold by including all title V 
stationary sources and minor sources with a PTE greater than 10 tons of 
VOC or 25 tons of NOX per year. Clark County DES based the 
inventory estimates on source reported actual 2017 emissions data but 
adjusted the reported values to reflect a typical ozone

[[Page 88304]]

season day at each emissions unit within the source facilities based on 
information provided by the facilities.
    Nonpoint sources include emissions from equipment, operations and 
activities that are numerous and in total have significant emissions. 
Clark County DES included emissions from minor sources, residential 
combustion, agricultural burning, industrial solvents and graphic arts, 
and degreasing operations. Clark County DES used several methods to 
estimate area source activity levels and emissions, including applying 
local activity levels, apportioning national or statewide activity 
levels to the local level, applying per capita emission factors 
considering county-specific populations and using specific method 
abstracts detailed within the submittal.
    Non-road emissions sources include equipment that either move under 
their own power or can be moved from site to site.
    The on-road emissions sector includes emissions from engines used 
primarily to propel equipment on highways and other roads, including 
passenger vehicles, motorcycles, and heavy-duty diesel trucks. Clark 
County DES used MOVES3, EPA's MOVES3 emissions factors, fleet data from 
Department of Motor Vehicles (DMV) registration data, Coordinated 
Research council (CRC) vehicle speed data, the Regional Transportation 
Commission (RTC) of Southern Nevada's transportation demand modeling 
results, vehicle classification data from the June 2018 Clark County 
Vehicle Classification Study,\31\ and 2017 Highway Performance 
Monitoring System (HPMS) data from the Nevada Department of 
Transportation (NDOT).
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    \31\ Clark County DES completed a vehicle classification study 
in June 2018. The study used 2014-2016 traffic count data collected 
by the Nevada Department of Transportation (NDOT). Clark County DES 
incorporated VMT mix profiles and temporal profiles, which DES 
incorporated into the 2017 MOVES3 input database.
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    Biogenic emissions are from vegetation and soil, and include crops, 
lawn grass, and forests. Clark County DES used the Biogenic Emissions 
Inventory System version 3.61 (BEIS3.61) embedded in the SMOKE 4.7 
model for the month of July to generate average ozone season day 
emissions for Clark County.
    The airport sector includes emissions from aircraft from commercial 
and federal aviation sources. Clark County DES relied on airport-
specific emissions inventory information provided by the Clark County 
Department of Aviation (CCDOA) for the five commercial airports located 
within the nonattainment area.
    Locomotives include emissions from railroad and high-speed 
passenger train emissions. Locomotive emissions were estimated by Clark 
County DES based on local activity data collected for the Clark County 
First Maintenance Plan and predicted emissions from high-speed 
passenger train service.
    ERCs refer to allowances earned through voluntary pollutant 
emissions reductions such as equipment shutdowns or voluntarily 
installed controls. Clark County adopted New Source Review (NSR) rule, 
Section 12.7.5--Emission Reduction credits into the SIP,\32\ allowing 
Clark County to adopt ERCs. In the Clark County First Maintenance Plan, 
Clark County banked NOX and VOC credits from the Clark 
County Department of Air Quality and Environmental Management (DAQEM) 
ERC Bank,\33\ Reid Gardner ERCs,\34\ and Mohave ERCs.\35\ In the Clark 
County Second Maintenance Plan, Clark County noted that ERCs have not 
changed from the Clark County First Maintenance Plan.
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    \32\ 79 FR 62350 (October 17, 2014).
    \33\ See ``DAQEM ERC Bank'' for a list of sources contributing 
to the DAQEM ERC Bank in Clark County.
    \34\ NDEP banked Reid Gardner ERCs after the NV Energy--Reid 
Gardner Station Power Plant, Unit #4 Steam Boiler was controlled 
with a low-NOX burner in January 2010.
    \35\ NDEP banked Mohave ERCs after the permanent shut down and 
dismantling of the Southern California Edison Mohave Generating 
Station in November 2009.
---------------------------------------------------------------------------

    The EPA has reviewed the emissions inventory submitted by Clark 
County and proposes to conclude that the plan's inventory is based on 
reasonable assumptions and methodologies, and that the inventory is 
comprehensive, current, accurate, and consistent with applicable CAA 
provisions and the Calcagni Memo. Therefore, we are proposing that the 
inventory is acceptable for use in demonstrating maintenance of the 
1997 ozone NAAQS.

C. Maintenance Demonstration

    CAA section 175A(a) requires that the maintenance plan ``provide 
for the maintenance of the national primary ambient air quality 
standard for such air pollutant in the area concerned for at least 10 
years after the redesignation.'' Generally, a state may demonstrate 
maintenance of the ozone NAAQS by either showing that future emissions 
of a pollutant or its precursors will not exceed the level of the 
attainment inventory or by modeling to show that the future mix of 
sources and emissions rates will not cause a violation of the 
NAAQS.\36\ For areas that are required under the Act to submit modeled 
attainment demonstrations, the maintenance demonstration should use the 
same level of modeling.\37\ The Clark County 8-hour ozone nonattainment 
area was not required to submit a modeled attainment demonstration, and 
thus, the Clark County Second Maintenance Plan may demonstrate 
maintenance based on a comparison of existing and future emissions of 
ozone precursors.\38\
---------------------------------------------------------------------------

    \36\ Calcagni Memo, 9-11.
    \37\ Id.
    \38\ A maintenance demonstration need not be based on ozone 
modeling. See Wall v. EPA, 265 F.3d. 426 (6th Cir. 2001); Sierra 
Club v. EPA, 375 F.3d 537 (7th Cir. 2004). See also 66 FR 53094 
(October 19, 2001), and 68 FR 25418 (May 12, 2003).
---------------------------------------------------------------------------

    Clark County used the 2017 national emissions inventory (NEI) data 
as the baseline to develop growth factors for point, nonpoint, and 
locomotive sources. Clark County DES used the EPA 2016 v.1 modeling 
platform emissions data to develop per-year growth adjustment factors 
for point, nonpoint, federal aviation, and locomotives. Clark County 
DES used local activity data to develop commercial airport growth 
factors and conducted MOVES3 modeling to project on-road and non-road 
emissions. The derived growth adjustment factors were used to 
extrapolate emissions to account for a 16-year (2017 through 2033) 
spread. The 2033 growth factors were multiplied by the 2017 actual 
emissions to produce the 2033 projected point source and various other 
stationary source emissions; including Residential Wood Combustion,\39\ 
non-point VOC,\40\ airport,\41\ and locomotive emissions.\42\ An 
interim year (2023) projected emissions inventory is also included. On-
road emissions were estimated for the 2017 base year and for projection 
years 2023 and 2033 and reflect a 32 percent decrease in VMT from 2017 
to 2023 and a 56 percent decrease in VMT from 2017 to 2033 based on 
Regional Transit Commission (RTC) projections.\43\
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    \39\ Clark County Second Maintenance Plan, Appendix A, 23.
    \40\ Clark County Second Maintenance Plan, Appendix A, 24.
    \41\ Clark County Second Maintenance Plan, Appendix A, 29.
    \42\ Clark County Second Maintenance Plan, Appendix A, 31.
    \43\ Clark County Second Maintenance Plan, 27, Table 6-1.
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    In addition to accounting for areawide growth trends, Clark County 
DES added emissions from specific projects that are expected to become 
operational during the second maintenance period,

[[Page 88305]]

including the proposed Southern Nevada Supplemental Airport, the 
proposed Sloan Regional Heliport, and DAF training program in the 
future-year emissions inventories, and also added in ERCs from certain 
stationary sources in the event that the ERCs are used for the purposes 
of issuing permits for new or modified stationary sources in the air 
quality planning area. We have reviewed the methods and assumptions, as 
described in connection with the attainment inventory, that Clark 
County DES used to project emissions to 2023 and 2033 for the various 
source categories and find them to be reasonable.
    Table 1 compares the VOC and NOX emissions estimated for 
the Clark County 8-hour ozone maintenance area for 2017 with those for 
2023 and 2033 by source category. The projected VOC and NOX 
emissions show that VOC and NOX emissions would remain well 
below the attainment levels throughout the second 10-year maintenance 
period and thereby adequately demonstrate maintenance through that 
period.
    In addition, historical monitoring data presented in the plan shows 
a gradual downward trend in ozone design values during 2008-2020. The 
1997 NAAQS level of 80 ppb was achieved in 2009, and the 2020 value of 
74 ppb is well below the NAAQS.\44\ This supports the maintenance 
demonstration, and the EPA expects this downward trend will continue 
given the projected emissions decreases.
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    \44\ Clark County Second Maintenance Plan, 12, Figure 2-1.
---------------------------------------------------------------------------

D. Verification of Continued Attainment

    NDEP and the Clark County Board of County Commissioners have the 
legal authority to implement and enforce the requirements of the Clark 
County Second Maintenance Plan. This includes the authority to adopt, 
implement and enforce any emissions control contingency measures 
determined to be necessary to correct ozone NAAQS violations. To verify 
continued attainment, Clark County DES commits in the Clark County 
Second Maintenance Plan to the continued operation of an ozone 
monitoring network that meets the EPA ambient air quality surveillance 
requirements.
    Secondly, the transportation conformity process represents another 
means by which to verify continued attainment of the 1997 8-hour ozone 
NAAQS in the Clark County 8-hour ozone area given the relative 
importance of motor vehicle emissions to the overall emissions 
inventories of ozone precursors.\45\
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    \45\ Clark County Second Maintenance Plan, Page 15.
---------------------------------------------------------------------------

    Lastly, while not cited in the plan, NDEP and Clark County DES must 
inventory emissions sources and report to the EPA on a periodic basis 
under 40 CFR part 51, subpart A (``Air Emissions Reporting 
Requirements''). These emissions inventory updates will provide a third 
means with which to track emissions in the area relative to those 
projected in the maintenance plan and thereby verify continued 
attainment of the NAAQS. These methods are sufficient for the purpose 
of verifying continued attainment.

E. Contingency Provisions

    Section 175A(d) of the Act requires that maintenance plans include 
contingency provisions, as the EPA deems necessary, to promptly correct 
any violations of the NAAQS that occur after redesignation of the area. 
Such provisions must include a requirement that the State will 
implement all measures with respect to the control of the air pollutant 
concerned which were contained in the SIP for the area before 
redesignation of the area as an attainment area.
    Under section 175A(d), contingency measures identified in the 
contingency plan do not have to be fully adopted at the time of 
redesignation. However, the contingency plan is an enforceable part of 
the SIP and should ensure that the contingency measures are adopted 
expeditiously once they are triggered by a specified event. The 
maintenance plan should clearly identify the measures to be adopted, a 
schedule and procedure for adoption and implementation, and a specific 
timeline for action by the State. As a necessary part of the plan, the 
State should also identify specific indicators or triggers, which will 
be used to determine when the contingency measures need to be 
implemented.
    As required by section 175A of the CAA, Clark County DES has 
adopted a contingency plan to address possible future ozone air quality 
problems.\46\ Clark County DES identifies the trigger date as 60 days 
after a determination of a confirmed violation of the 1997 8-hour ozone 
NAAQS. Within 45 days of the trigger date, Clark County will notify the 
EPA that it is evaluating potential contingency measures. Within 90 
days of the trigger date, Clark County will send a report to the EPA 
and then will initiate a public process to consider the recommended 
contingency measures, including soliciting stakeholder involvement and 
holding public hearings. The necessary emissions control measures will 
be adopted and implemented no later than 18 months after the trigger 
date.
---------------------------------------------------------------------------

    \46\ Contingency Measure Revision, Section 2, ``Contingency 
Measures Plan.''
---------------------------------------------------------------------------

    Potential contingency measures listed in the maintenance plan are 
those emissions controls or other measures that Clark County, the 
Nevada State Board of Agriculture, and/or the Nevada State 
Environmental Commission may choose to adopt and implement in response 
to the contingency trigger. The contingency measures plan in the 
Contingency Measure Revision lists the following potential contingency 
measures that will be considered for adoption and implementation by the 
applicable State or County agency, but the Plan indicates that the list 
is not to be considered exclusive:
     Reid vapor pressure reduction (i.e., in gasoline sold 
during the summer ozone season; would need to be adopted and 
implemented by the Nevada State Board of Agriculture);
     Inspection/maintenance program changes and additions 
(e.g., lowering the cut points for VOCs and NOX applicable 
to pre-1996 vehicles; would need to be adopted and implemented by the 
State Environmental Commission and/or the State Department of Motor 
Vehicles);
     Consumer and commercial products (Clark County would be 
responsible for adoption and implementation);
     Architectural surface coatings (Clark County would be 
responsible for adoption and implementation);
     Lawn and garden equipment use (Clark County would be 
responsible for adoption and implementation); and
     Establish/enhance trip reduction programs (Clark County 
and the RTC would be responsible for adoption and implementation).
    Upon our review of the plan, we find that the contingency 
provisions of the Contingency Measure Revision clearly identify 
specific contingency measures, contain tracking and triggering 
mechanisms to determine when contingency measures are needed, contain a 
description of the process of recommending and implementing contingency 
measures, and contain specific timelines for action. Thus, we conclude 
that the contingency provisions of the Contingency Measure Revision are 
adequate to ensure prompt correction of a violation and therefore 
comply with section 175A(d) of the Act.

F. Motor Vehicle Emissions Budgets for Transportation Conformity

    Section 176(c) of the CAA requires federal actions in nonattainment 
and

[[Page 88306]]

maintenance areas to conform to the SIP's goals of eliminating or 
reducing the severity and number of violations of the NAAQS and 
achieving expeditious attainment of the standards. Conformity to the 
SIP's goals means that such actions will not: (1) cause or contribute 
to violations of a NAAQS, (2) worsen the severity of an existing 
violation, or (3) delay timely attainment of any NAAQS or any interim 
milestone.
    Actions involving Federal Highway Administration (FHWA) or Federal 
Transit Administration (FTA) funding or approval are subject to the 
EPA's transportation conformity rule, codified at 40 CFR part 93, 
subpart A. Under this rule, RTCs in nonattainment and maintenance areas 
coordinate with state and local air quality and transportation 
agencies, the EPA, FHWA, and FTA to demonstrate that an area's regional 
transportation plans and transportation improvement programs conform to 
the applicable SIP. This demonstration is typically done by showing 
that estimated emissions from existing and planned highway and transit 
systems are less than or equal to the motor vehicle emissions budgets 
(``budgets'') contained in submitted or approved control strategy SIPs 
and maintenance plans.\47\
---------------------------------------------------------------------------

    \47\ Control strategy SIPs refer to RFP and attainment 
demonstration SIPs. 40 CFR 93.101.
---------------------------------------------------------------------------

    These control strategy SIPs and maintenance plans typically set 
budgets for criteria pollutants and/or their precursors to address 
pollution from cars and trucks. Budgets are generally established for 
specific years and specific pollutants or precursors. Maintenance plan 
submittals should identify budgets for transportation-related VOC and 
NOX emissions in the last year of the maintenance period.
    For budgets in a maintenance plan to be approvable, they must meet, 
at a minimum, the EPA's adequacy criteria.\48\ To meet these 
requirements, the budgets must be consistent, when considered with 
emissions from all other sources, with maintenance of the NAAQS and 
reflect all the motor vehicle control measures relied upon for the 
maintenance demonstration. The EPA's process for determining adequacy 
of a budget consists of three basic steps: (1) providing public 
notification of a SIP submission; (2) providing the public the 
opportunity to comment on the MVEB during a public comment period; and 
(3) making a finding of adequacy. The process for determining the 
adequacy of a submitted budget is codified at 40 CFR 93.118(f). The EPA 
can notify the public by either posting an announcement that the EPA 
has received SIP budgets on the EPA's adequacy website, or via a 
Federal Register notice of proposed rulemaking when the EPA reviews the 
adequacy of a maintenance plan budget simultaneously with its review 
and action on the SIP submittal itself.\49\
---------------------------------------------------------------------------

    \48\ 40 CFR 93.118(e)(4) and (5). For more information on the 
transportation conformity requirement and applicable policies on 
MVEBs, please visit our transportation conformity website at: http://www.epa.gov/otaq/stateresources/transconf/index.htm.
    \49\ 40 CFR 93.118(f)(2).
---------------------------------------------------------------------------

    Clark County's Second Maintenance Plan contains VOC and 
NOX budgets for 2017, 2023 and 2033. Any and all comments on 
the approvability of the budgets should be submitted during the comment 
period stated in the DATES section of this document.
    The EPA proposes to approve 2017, 2023, and 2033 budgets in the 
Clark County Second Maintenance Plan for transportation conformity 
purposes in the final rulemaking on Clark County's ozone redesignation 
request. If the EPA approves the budgets in the final rulemaking 
action, the new budgets must be used in future transportation 
conformity determinations for Clark County for the 2015 ozone standard. 
The new budgets, if approved in the final rulemaking, will be effective 
on the date of the EPA's final rulemaking in the Federal Register. The 
applicable VOC and NOX MVEBs for the Clark County ozone 
nonattainment area are defined in table 2.

                   Table 2--Proposed Motor Vehicle Emissions Budgets (MVEBs) for Clark County
----------------------------------------------------------------------------------------------------------------
                                                  VOC (tpd, average summer          NOX (tpd, average summer
                 Budget year                              weekday)                          weekday)
----------------------------------------------------------------------------------------------------------------
2017........................................                             26.27                              42.2
2023........................................                             20.92                             26.77
2033........................................                             15.51                             23.35
----------------------------------------------------------------------------------------------------------------
From Table 6-3 and 6-4 of the Clark County Second Maintenance Plan.

    The MVEBs are the on-road mobile source VOC and NOX 
emissions for Clark County for 2017, 2023 and 2033. The budgets are 
compatible with the 2017, 2023, and 2033 on-road mobile source VOC and 
NOX emissions included in Clark County's 2017, 2023, and 
2033 VOC and NOX emission inventories, as summarized in 
Table 2. The derivation of the budgets is thoroughly discussed in 
Appendix A, Chapter 2 of Clark County's Second Maintenance Plan. While 
the Plan includes budgets for 2017, we are not evaluating the 2017 
budgets because that year would not be used in any future conformity 
determination because the plan contains budgets for 2023 and because 
2017 budgets are not required for the submitted second maintenance 
plan.
    We evaluated the budgets against our adequacy criteria in 40 CFR 
93.118(e)(4) and (5) as part of our review of the budget's 
approvability and expect to complete the adequacy review of the budgets 
concurrent with our final action on the Clark County's Second 
Maintenance Plan. The EPA is not required under its transportation 
conformity rule to find budgets adequate prior to proposing approval of 
them. In this notice, the EPA is announcing that the adequacy process 
for these budgets begins, and the public has 30 days to comment on 
their adequacy, per the transportation conformity rule at 40 CFR 
93.118(f)(2)(i) and (ii).
    Clark County DES developed the budgets for 2023 and 2033 using on-
road motor vehicle emission estimates made using the EPA's MOVES3 
model, fleet data from DMV registration data, CRC vehicle speed data, 
NDOT HPMS data, travel demand modeling from the Regional Transportation 
Commission and vehicle classification data from the June 2018 Clark 
County On-road Vehicle Classification Study.
    As documented in the separate memorandum \50\ included in the 
docket for this rulemaking, we preliminarily conclude that the budgets 
in the Second Maintenance Plan meet each adequacy criterion. While 
adequacy and approval

[[Page 88307]]

are two separate actions, reviewing the budgets in terms of the 
adequacy criteria informs the EPA's decision to propose to approve the 
budgets. We have completed our detailed review and are proposing to 
approve the demonstration of maintenance for the 1997 ozone maintenance 
area through the year 2033. We have also reviewed the budgets in Clark 
County's Second Maintenance Plan and found that they are consistent 
with the maintenance demonstration for which we are proposing approval, 
are clearly identified and precisely quantified, are based on control 
measures that have already been adopted and implemented, and meet all 
other applicable statutory and regulatory requirements including the 
adequacy criteria in 40 CFR 93.118(e)(4) and (5). The EPA is proposing 
to approve the budgets for 2023 and 2033 as part of our approval of 
Clark County's Second Maintenance Plan. At the point when we either 
finalize the adequacy process or approve the budgets as proposed 
(whichever occurs first; note that they could also occur concurrently 
per 40 CFR 93.118(f)(2)(iii)), the budgets must be used by the Regional 
Transportation Commission (i.e., the Metropolitan Planning Organization 
(MPO) for this area) for transportation conformity determinations for 
the Clark County 2015 ozone nonattainment area.
---------------------------------------------------------------------------

    \50\ See the EPA Memorandum dated August 22, 2023 titled: 
Adequacy Documentation for Motor Vehicle Emissions Budgets in Clark 
County Second Maintenance Plan.''
---------------------------------------------------------------------------

VI. Environmental Justice Considerations

    The EPA performed a screening-level analysis using the EPA's 
environmental justice (EJ) screening and mapping tool (``EJSCREEN''). 
Our screening-level analysis included multiple environmental and 
demographic indicators, including the EJSCREEN ``Demographic Index,'' 
which is the average of an area's percentage of minority and low-income 
populations. The Demographic Index of Clark County is at the 68th 
percentile, compared to the United States as a whole.\51\ The results 
of this analysis are being provided for informational and transparency 
purposes.
---------------------------------------------------------------------------

    \51\ Clark County Ozone NAA EJSCREEN Report dated February 10, 
2023.
---------------------------------------------------------------------------

    This action addresses a plan for continued maintenance of the 1997 
ozone NAAQS for Clark County. Approval of this plan does not impose any 
additional regulatory requirements on sources beyond those imposed by 
state law. As discussed in this document, Nevada has demonstrated that 
the Clark County is attaining the 1997 ozone NAAQS and the Clark County 
Second Maintenance Plan provides for the maintenance of the NAAQS for 
the reminder of the maintenance period. We expect that this action will 
generally be neutral or contribute to reduced environmental and health 
impacts on all populations in Clark County, including people of color 
and low-income populations. At a minimum, this action would not worsen 
any existing air quality and is expected to ensure the area is meeting 
requirements to maintain air quality standards. Further, there is no 
information in the record indicating that this action is expected to 
have disproportionately high or adverse human health or environmental 
effects on a particular group of people.

VII. Proposed Action and Request for Public Comment

    Under CAA section 110(k)(3), and for the reasons set forth in this 
document, the EPA is proposing to approve the Clark County Second 
Maintenance Plan submitted by NDEP on January 24, 2022, as a revision 
to the Nevada SIP.\52\ We are proposing to approve the maintenance 
demonstration and contingency provisions as meeting all applicable 
requirements for maintenance plans and related contingency provisions 
in CAA section 175A, and the budgets for 2023 and 2033 (shown in Table 
2) for transportation conformity purposes as we find they meet all 
applicable criteria for such budgets including the adequacy criteria 
under 40 CFR 93.118(e).
---------------------------------------------------------------------------

    \52\ Clark County Second Maintenance Plan (submitted 
electronically January 24, 2022).
---------------------------------------------------------------------------

    We are soliciting comments on these proposed actions. We will 
accept comments from the public for 30 days following publication of 
this proposal in the Federal Register and will consider any relevant 
comments before taking final action.

VIII. 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);
     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
     Will not have disproportionately high and adverse human 
health or environmental effects on minority populations, low-income 
populations and/or indigenous peoples, as specified in Executive Order 
12898 (59 FR 7629, February 16, 1994), as discussed in section VI of 
this proposal.
    In addition, there are no areas of Indian country within the 
planning area, and the state plan for which the EPA is proposing 
approval does not 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 Clark County Second 
Maintenance Plan does not apply, and therefore, this proposed action 
does not have tribal implications and would not, if approved, 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, Nitrogen dioxide, Particulate matter, Sulfur dioxide, 
Reporting and recordkeeping requirements, Volatile organic compounds.

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

[[Page 88308]]

    Dated: December 14, 2023.
Martha Guzman Aceves,
Regional Administrator, Region IX.
[FR Doc. 2023-27874 Filed 12-20-23; 8:45 am]
BILLING CODE 6560-50-P