[Federal Register Volume 89, Number 74 (Tuesday, April 16, 2024)]
[Proposed Rules]
[Pages 26817-26835]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-08121]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R09-OAR-2023-0448; FRL-11677-01-R9]


Approval and Promulgation of Implementation Plans; State of 
California; Coachella Valley; Extreme Attainment Plan for 1997 8-Hour 
Ozone Standards

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing to 
approve state implementation plan (SIP) revisions submitted by the 
State of California to meet Clean Air Act (CAA) requirements for the 
1997 8-hour ozone

[[Page 26818]]

national ambient air quality standards (NAAQS or ``standards'') in the 
Riverside County (Coachella Valley), CA nonattainment area (``Coachella 
Valley''). These SIP revisions address the ``Extreme'' nonattainment 
area requirements for the 1997 8-hour ozone standards, including the 
requirements for the attainment demonstration, reasonable further 
progress demonstration, and reasonably available control measures 
demonstration, among others.

DATES: Comments must be received on or before May 16, 2024.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R09-
OAR-2023-0448 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: Tom Kelly, Geographic Strategies and 
Modeling Section (AIR-2-2), U.S. Environmental Protection Agency, 
Region IX, (415) 972-3856, [email protected].

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

Table of Contents

I. The 1997 8-Hour Ozone Standards and the Coachella Valley 
Nonattainment Area
    A. Background on the 1997 8-Hour Ozone Standards
    B. The Coachella Valley 1997 8-Hour Ozone Nonattainment Area
II. CAA and Regulatory Requirements for Ozone Nonattainment Area 
SIPs
III. CARB's SIP Submittals To Address the Extreme Requirements for 
the 1997 8-Hour Ozone Standards in the Coachella Valley
    A. CARB's SIP Submittals
    B. CAA Procedural and Administrative Requirements for SIP 
Submittals
IV. Review of the Coachella Valley Ozone Plan
    A. Emissions Inventories
    B. Reasonably Available Control Measures Demonstration and 
Adopted Control Strategy
    C. Attainment Demonstration
    D. Rate of Progress and Reasonable Further Progress 
Demonstrations
    E. Vehicle Miles Travelled Offset Demonstration
    F. Clean Fuels or Advanced Control Technology for Boilers
    G. Other CAA Requirements
V. Environmental Justice Considerations
VI. The EPA's Proposed Action and Public Comment
VII. Statutory and Executive Order Reviews

I. The 1997 8-Hour Ozone Standards and the Coachella Valley 
Nonattainment Area

A. Background on the 1997 8-Hour Ozone Standards

    Ground-level ozone is formed when oxides of nitrogen 
(NOX) and volatile organic compounds (VOC) react in the 
presence of sunlight.\1\ These two pollutants, referred to as ozone 
precursors, are emitted by many types of pollution sources, including 
on- and off-road motor vehicles and engines, power plants and 
industrial facilities, and smaller area sources such as lawn and garden 
equipment and paints.
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    \1\ The State of California uses the term Reactive Organic Gases 
(ROG) rather than VOC in some of its ozone-related SIP submissions. 
As a practical matter, ROG and VOC refer to the same set of chemical 
constituents and for simplicity, we refer to this set of gases as 
VOC.
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    Health effects associated with exposure to ground-level ozone 
include: reduced lung function, making it more difficult for people to 
breathe as deeply and vigorously as normal; irritated airways, causing 
coughing, sore or scratchy throat, pain when taking a deep breath and 
shortness of breath; increased frequency of asthma attacks; 
inflammation of and damage to the lining of the lung; increased 
susceptibility to respiratory infection; and aggravation of chronic 
lung diseases such as asthma, emphysema, and bronchitis. Ozone may 
continue to cause lung damage even when the symptoms have disappeared 
and breathing ozone may contribute to premature death, especially in 
people with heart and lung disease.\2\
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    \2\ EPA, ``Fact Sheet, Final Revisions to the National Ambient 
Air Quality Standards for Ozone,'' March 2008.
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    In 1979, under section 109 of the Clean Air Act (CAA), the EPA 
established primary and secondary NAAQS for ozone at 0.12 parts per 
million (ppm) averaged over a 1-hour period.\3\ On July 18, 1997, the 
EPA revised the primary and secondary standards for ozone to set the 
acceptable level of ozone in the ambient air at 0.08 ppm, averaged over 
an 8-hour period (``1997 8-hour ozone standards'').\4\ The EPA set the 
1997 8-hour ozone standards based on scientific evidence demonstrating 
that ozone causes adverse health effects at lower concentrations and 
over longer periods of time than was understood when the previous 1-
hour ozone standards were set. The EPA determined that the 1997 8-hour 
standards 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. The 8-hour ozone 
standards were further strengthened in 2008 and 2015.\5\ Although the 
1979 1-hour ozone standards and the 1997 8-hour ozone standards have 
subsequently been revoked following the promulgation of more stringent 
ozone standards, certain requirements that had applied under the 
revoked standards continue to apply under the anti-backsliding 
provisions of CAA section 172(e), including an approved attainment 
plan.\6\
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    \3\ 44 FR 8202 (February 8, 1979).
    \4\ 62 FR 38856.
    \5\ In 2008, the EPA revised and strengthened the NAAQS for 
ozone by setting the acceptable level of ozone in the ambient air at 
0.075 ppm, averaged over an 8-hour period. 73 FR 16436 (March 27, 
2008). In 2015, the EPA further tightened the 8-hour ozone standards 
to 0.070 ppm. 80 FR 65292 (October 26, 2015). The EPA has approved 
most elements of the 2008 ozone attainment plan for the Coachella 
Valley. 85 FR 57714 (September 16, 2020). The EPA has yet to act on 
the Coachella Valley attainment plan for the 2015 ozone NAAQS, 
submitted electronically on February 23, 2023. This action applies 
only to the 1997 8-hour ozone standards and does not address 
requirements for the 2008 and 2015 8-hour ozone standards.
    \6\ 80 FR 12264, 12296 (March 6, 2015).
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B. The Coachella Valley 1997 8-Hour Ozone Nonattainment Area

    Following promulgation of a new or revised NAAQS, the EPA is 
required by the CAA to designate areas throughout the nation as 
attaining or not attaining the standards. Effective June 15, 2004, the 
EPA designated nonattainment areas for the 1997 8-hour ozone 
standards.\7\ The designations and classifications for

[[Page 26819]]

the 1997 8-hour ozone standards for California areas are codified at 40 
CFR 81.305. In a rule governing certain facets of implementation of the 
1997 8-hour ozone standards (the ``Phase 1 Rule''), the EPA classified 
the Coachella Valley as ``Serious'' nonattainment for the 1997 8-hour 
ozone standards, with an attainment date no later than June 15, 
2013.\8\ On November 28, 2007, the California Air Resources Board 
(CARB) requested that the EPA reclassify the Coachella Valley 1997 8-
hour ozone nonattainment area from Serious to ``Severe-15.'' The EPA 
granted the reclassification, effective June 4, 2010, with an 
attainment date of not later than June 15, 2019.\9\ On June 11, 2019, 
CARB requested another reclassification for the Coachella Valley, from 
Severe-15 to ``Extreme'' nonattainment, which the EPA granted in a 
final rule published July 10, 2019.\10\ This reclassification to 
Extreme applied only to the portions of the Coachella Valley subject to 
state jurisdiction. At this time, areas of Indian country within the 
nonattainment area remain classified as Severe-15 for the 1997 8-hour 
ozone standards.\11\ On January 15, 2020, we published a final rule 
setting a deadline of February 20, 2021, for the state to submit a SIP 
revision addressing the Extreme requirements of CAA section 182(e) and 
the revised title V and new source review rules for the Coachella 
Valley.\12\
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    \7\ 69 FR 23858 (April 30, 2004).
    \8\ Id. at 23885 and 23886.
    \9\ 75 FR 24409 (May 5, 2010).
    \10\ 84 FR 32841 (July 10, 2019).
    \11\ Id.; see also 40 CFR 81.305.
    \12\ 85 FR 2311 (January 15, 2020). See also proposal at 84 FR 
44801 (August 27, 2019).
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    The EPA previously approved many elements of the Coachella Valley's 
Severe attainment plan in a final rule dated June 12, 2017,\13\ 
including the reasonably available control measure (RACM) demonstration 
as meeting the requirements of CAA section 172(c)(1) and 40 CFR 
51.1105(a)(1) and 51.1100(o)(17); the rate of progress (ROP) and 
reasonable further progress (RFP) demonstrations as meeting the 
requirements of CAA sections 172(c)(2) and 182(c)(2)(B) and 40 CFR 
51.1105(a)(1) and 51.1100(o)(4); the attainment demonstration as 
meeting the requirements of CAA section 182(c)(2)(A) and 40 CFR 
51.1105(a)(1) and 51.1100(o)(12); and the demonstration that the SIP 
submittal provides for transportation control strategies and measures 
sufficient to offset any growth in emissions from growth in vehicle 
miles travelled (VMT) or the number of vehicle trips, and to provide 
for RFP and attainment, as meeting the requirements of CAA section 
182(d)(1)(A) and 40 CFR 51.1105(a)(1) and 51.1100(o)(10). The EPA did 
not act on the contingency measures submitted with the Severe-15 
attainment plan, which were subsequently withdrawn by CARB, and we did 
not act on the motor vehicle emissions budgets, because the associated 
transportation conformity demonstration is not required for a revoked 
NAAQS. The EPA also approved the Enhanced motor vehicle inspection and 
maintenance (I/M) program for the Coachella Valley in a final rule 
published on July 1, 2010.\14\
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    \13\ 82 FR 26854.
    \14\ 75 FR 38023.
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    The Coachella Valley area is located within Riverside County.\15\ 
The Coachella Valley is under the jurisdiction of the South Coast Air 
Quality Management District (SCAQMD or ``District''), which also 
oversees air quality in the upwind South Coast Air Basin. The District 
and CARB are responsible for adopting and submitting plans to attain 
the 1997 8-hour ozone standards for nonattainment areas in their 
jurisdiction.
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    \15\ For a precise description of the geographic boundaries of 
the area, see 40 CFR 81.305.
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    Ground level ozone in the Coachella Valley ``is both directly 
transported from the [South Coast Air Basin] and formed photochemically 
from precursors emitted upwind and within the Coachella Valley.'' \16\ 
The South Coast Air Basin is home to a much larger population than 
Coachella Valley and, based on inventory data from 2018, emissions of 
NOX and VOC in the South Coast Air Basin are more than 20 
times larger than those of Coachella Valley.\17\ Therefore, attainment 
of the 1997 8-hour ozone standards in Coachella Valley is heavily 
dependent on upwind reductions in the South Coast Air Basin. The 
largest sources of precursors are at the coastal and central portions 
of South Coast Air Basin. The area's prevailing winds transport ozone 
precursors inland, forming ozone along the way. Maximum ozone 
concentrations occur ``in the inland valleys of the Basin, extending 
from eastern San Fernando Valley through the San Gabriel Valley into 
the Riverside-San Bernardino area and the adjacent mountains.'' \18\ As 
pollution is further transported through the San Gorgonio Pass into the 
Coachella Valley, ozone concentrations typically decrease from dilution 
with cleaner air, but ozone standards are still exceeded.
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    \16\ SCAQMD, ``Final Coachella Valley Extreme Area Plan for the 
1997 8-Hour Ozone Standard,'' dated December 2020, (``Coachella 
Valley Ozone Plan''), p. 2-1.
    \17\ Id. at 3-13.
    \18\ Id. at 2-1.
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    Air quality in the Coachella Valley has steadily improved in recent 
years. Design values have declined from 0.108 ppm in 2003 to 0.087 ppm 
in 2022.\19\ Design values are used to designate and classify 
nonattainment areas, as well as to assess progress towards meeting the 
air quality standards.\20\
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    \19\ EPA, Design Values Report for the Joshua Tree National 
Monument, Indio, and Palm Springs monitors for 2021, 2021, and 2022, 
March 8, 2023, and contained in the docket for this proposed action.
    \20\ For more information about ozone design values, see 40 CFR 
50, Appendix I.
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II. CAA and Regulatory Requirements for Ozone Nonattainment Area SIPs

    States must implement the 1997 8-hour ozone standards under Title 
1, Part D of the CAA, which includes section 172, ``Nonattainment plan 
provisions,'' and subpart 2, ``Additional Provisions for Ozone 
Nonattainment Areas'' (sections 181-185).
    To assist states in developing effective plans to address ozone 
nonattainment, the EPA issued an implementation rule for the 1997 8-
hour ozone standards (``1997 Ozone Implementation Rule''). This rule 
was finalized in two phases. The first phase of the rule addressed 
classifications for the 1997 8-hour ozone standards; applicable 
attainment dates for the various classifications; the timing of 
emissions reductions needed for attainment; and identified applicable 
requirements, such as clean fuels for boilers.\21\ The second phase 
addressed SIP submittal dates and the requirements for reasonably 
available control technology (RACT) and RACM, RFP, modeling and 
attainment demonstrations, contingency measures, and new source 
review.\22\ The rule was codified at 40 CFR part 51, subpart X.
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    \21\ 69 FR 23951 (April 30, 2004).
    \22\ 70 FR 71612 (November 29, 2005).
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    The EPA announced the revocation of the 1997 8-hour ozone standards 
and the anti-backsliding requirements that apply upon revocation in a 
rulemaking that established final implementation rules for the 2008 8-
hour ozone NAAQS.\23\ Under these anti-backsliding requirements, areas 
that were designated as nonattainment for the 1997 8-hour ozone 
standards at the time the standards were revoked continue to be subject 
to certain SIP requirements that had previously applied based on area 
classifications for the standards.\24\ Thus, although the 1997 8-hour 
ozone standards have been revoked, the Coachella Valley remains subject 
to

[[Page 26820]]

many requirements for these standards as applicable to ``Extreme'' 
nonattainment areas.
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    \23\ 80 FR 12264.
    \24\ Id. at 12296; 40 CFR 51.1105 and 51.1100(o).
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    We discuss the CAA and regulatory requirements for 1997 8-hour 
ozone nonattainment plans in more detail in the following section of 
this proposed rulemaking.

III. CARB's SIP Submittals To Address the Extreme Requirements for the 
1997 8-Hour Ozone Standards in the Coachella Valley

A. CARB's SIP Submittals

1. The Coachella Valley Ozone Plan
    On December 29, 2020, CARB submitted the ``Final Coachella Valley 
Extreme Area Plan for the 1997 8-Hour Ozone Standard,'' dated December 
2020 (``Coachella Valley Ozone Plan'' or ``Plan''), to the EPA as a 
revision to the California SIP.\25\ The Plan addresses many of the 
Extreme nonattainment area requirements for the Coachella Valley for 
the 1997 8-hour ozone standards.
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    \25\ Letter dated December 28, 2020, from Richard W. Corey, 
CARB, to John W. Busterud, EPA, Subject: ``Coachella Valley Extreme 
Area Plan for the 1997 8-Hour Ozone Standard'' (submitted 
electronically December 29, 2020).
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    The Coachella Valley Ozone Plan includes the District's resolution 
of approval for the Plan (District Board Resolution 20-22) and the 
executive order commemorating CARB's adoption of the Plan as a revision 
to the California SIP (Executive Order S-20-34).\26\ The Plan addresses 
the requirements for emissions inventory; RACM demonstration and 
adopted control strategy; attainment demonstration; ROP and RFP 
demonstrations; and clean fuels for boilers.
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    \26\ SCAQMD Board Resolution 20-22, December 4, 2020; Executive 
Order S-20-34, ``Coachella Extreme Ozone Plan SIP Submittal,'' 
December 28, 2020.
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    The Plan is organized into an executive summary, seven sections, 
and three appendices. Section 1, ``Introduction,'' identifies the 
nonattainment area and the nonattainment status for all EPA ozone 
standards, including the 1997 8-hour ozone standards; provides a 
history of air quality planning for the 1997 8-hour ozone standards; 
and explains the purpose of the Plan. Section 2, ``Air Quality 
Trends,'' describes the formation of ground-level ozone generally and 
specific factors that contribute to ozone formation in the Coachella 
Valley, and provides historic monitoring data and related discussion. 
Section 3, ``Base Year and Future Year Emissions,'' describes the 
methodology used for the area's emissions inventories, citing to the 
``Final 2016 Air Quality Management Plan'' (``2016 AQMP'') \27\ where 
appropriate, and discusses the modeled inventories in detail. Section 
4, ``Control Strategy,'' describes District and CARB rules that will 
achieve the emissions reductions relied upon in the Plan. Section 5, 
``Future Air Quality,'' describes the modeling approach, including 
inputs, assumptions, methodology, and weight of evidence analysis 
(WOE). Section 6, ``Other Clean Air Act Requirements'' addresses 
various Extreme area requirements, including for RFP, RACT, RACM, 
contingency measures, offsetting of increases in VMT, NSR requirements, 
use of clean fuels or advanced control technology for boilers, and 
traffic control measures during heavy traffic hours. Sections 7 through 
9 address various procedural requirements, including compliance with 
the California Environmental Quality Act, and notice and comment 
procedures. The Plan includes three supporting appendices, which 
describe the emissions inventories and existing District and CARB rules 
and regulations relied on in the Plan.
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    \27\ SCAQMD, ``Final 2016 Air Quality Management Plan,'' dated 
March 2017, submitted electronically by CARB to the EPA on April 27, 
2017, and approved by the EPA on September 16, 2020 (85 FR 57714). 
The 2016 AQMP includes a Coachella Valley attainment plan for the 
2008 ozone standards.
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2. The Coachella Valley VMT Offset Demonstration
    On March 18, 2021,\28\ CARB submitted the ``VMT Offset 
Demonstration.'' \29\ The VMT Offset Demonstration is intended to show 
compliance with the requirement at CAA section 182(d)(1) for 
nonattainment areas classified Severe or Extreme to adopt sufficient 
transportation control strategies (TCSs) and transportation control 
measures (TCMs) to offset any growth in VMT.
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    \28\ Letter dated March 15, 2021, from Richard W. Corey, CARB, 
to Deborah Jordan, EPA (submitted electronically March 18, 2021).
    \29\ CARB, ``Staff Report, 2020 Coachella Valley Vehicle Miles 
Traveled Emissions Offset Demonstration,'' January 22, 2021.
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    The VMT Offset Demonstration contains an Executive Summary, 
Introduction, Methodology, Staff Recommendations, and appendices. The 
appendices contain the following sections: ``Sensitivity Test to 
Estimate Emissions for the 2023 Attainment Year with Motor Vehicle 
Control Program Frozen at 2002;'' ``EMFAC2014 Analysis;'' \30\ 
``EMFAC2011 Analysis;'' \31\ and ``Summary.''
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    \30\ EMFAC2014 is the 2014 version of CARB's Emissions Factor 
model.
    \31\ EMFAC2011 is the 2011 version of CARB's Emissions Factor 
model.
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    The VMT Offset Demonstration includes a base year emissions 
estimate and three different estimates for the 2023 attainment year. 
One estimate has 2023 on-road vehicle emissions controls frozen as the 
requirements existed in 2002. One estimate shows 2023 emissions 
freezing the VMT at the levels from 2002. The final estimate reflects 
expected emissions for 2023 based on the submitted control strategy, 
which, as described further in Section IV.E of this document, must be 
less than both previous estimates for 2023 for an adequate VMT offset 
demonstration.
    As the VMT Offset Demonstration explains, several post-2002 
emissions control measures are factored into EMFAC2017 (the latest CARB 
model for on-road emissions at the time the demonstration was prepared) 
and cannot be removed. To correct this, the VMT Offset Demonstration 
includes the results of a sensitivity analysis to determine the 
emissions reductions associated with CARB's Advanced Clean Cars program 
and the Truck and Bus Regulations (calculated using EMFAC2014), and the 
additional stringency of CARB's inspection and maintenance programs 
(calculated using EMFAC2011).

B. CAA Procedural and Administrative Requirements for SIP Submittals

    CAA sections 110(a)(1) and (2) and 110(l) require a state to 
provide reasonable public notice and opportunity for public hearing 
prior to the adoption and submittal of a SIP or SIP revision. To meet 
this requirement, every SIP submittal should include evidence that the 
state provided adequate public notice and an opportunity for a public 
hearing, consistent with the EPA's implementing regulations in 40 CFR 
51.102.
    The SCAQMD provided public notice of its intent to approve the 
Coachella Valley Ozone Plan on November 4, 2020.\32\ The public comment 
period ended with a public hearing on December 4, 2020; no comments 
were submitted during the public hearing.\33\ The SCAQMD responded to 
written comments in Section 9 of the Plan. The SCAQMD Governing Board 
documented the adoption of the Plan in Board Resolution 20-22, dated 
December 4, 2020. In addition to the comment period and hearing, the 
SCAQMD convened several steering committees and advisory groups 
beginning in August

[[Page 26821]]

2020.\34\ As documented in Executive Order S-20-34, CARB determined 
that the Plan met the requirements of the Act, adopted the Plan, and 
ordered it to be submitted to the EPA for inclusion in the SIP.
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    \32\ SCAQMD, Proof of Publication for Notice of Public Hearing, 
dated November 4, 2020.
    \33\ SCAQMD, Draft Minutes of Public Hearing, dated December 4, 
2020.
    \34\ SCAQMD, Governing Board Package for the Coachella Valley 
Extreme Area Plan, dated December 4, 2020, Public Process, page 3.
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    The Plan includes proof of publication for the notice of the 
District public hearings, as evidence that all hearings were properly 
noticed. Therefore, we find the Coachella Valley Ozone Plan meets the 
procedural requirements of CAA sections 110(a) and 110(l).
    CARB provided public notice of its intent to approve the VMT Offset 
Demonstration on January 21, 2021. The public comment period ended with 
a board meeting on February 25, 2021. One person commented during the 
public meeting, urging progress in addressing air pollution in the 
Coachella Valley without directly addressing the VMT Offset 
Demonstration. The CARB Governing Board documented the adoption of the 
VMT Offset Demonstration in Board Resolution 21-1, dated February 25, 
2021.
    CAA section 110(k)(1)(B) requires that the EPA determine whether a 
SIP submittal is complete within 60 days of receipt. This section of 
the CAA also provides that any plan that the EPA has not affirmatively 
determined to be complete or incomplete is deemed complete by operation 
of law six months after the date of submittal. The SIP submittal for 
the Coachella Valley Ozone Plan became complete by operation of law on 
June 28, 2021, and the submittal for the VMT Offset Demonstration 
became complete by operation of law on September 18, 2021.

IV. Review of the Coachella Valley Ozone Plan

A. Emissions Inventories

1. Requirements for Emissions Inventories
    CAA section 182(a)(1) requires each state with an ozone 
nonattainment area classified under subpart 2 to submit a 
``comprehensive, accurate, current inventory of actual emissions from 
all sources'' of the relevant pollutants in accordance with guidance 
provided by the Administrator. While this inventory is not a specific 
requirement under the anti-backsliding provisions at 40 CFR 51.1105 and 
51.1100(o), it provides support for demonstrations required under these 
anti-backsliding rules. Additionally, a baseline emissions inventory is 
needed for the attainment demonstration and for meeting RFP 
requirements. The 1997 Ozone Implementation Rule identifies 2002 as the 
baseline year for RFP purposes.\35\ Emissions inventory guidance issued 
by EPA sets specific planning requirements pertaining to future 
milestone years for reporting RFP and to attainment demonstration 
years.\36\ Key RFP analysis years in the RFP demonstration include 2008 
and every subsequent 3 years until the attainment date.
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    \35\ 69 FR 23951, 23980 (April 30, 2004).
    \36\ 70 FR 71612.
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    We have evaluated the emissions inventories in the Coachella Valley 
Ozone Plan to determine if they are consistent with EPA guidance and 
adequate to support the Plan's RACM, RFP, ROP, and attainment 
demonstrations.
2. Emissions Inventories in the Coachella Valley Ozone Plan
    Chapter 3 and Appendix I of the Plan contain detailed emissions 
estimates. The District's process for developing these emissions 
estimates followed a similar methodology to the inventories in the 2016 
AQMP.\37\ In general, Appendix III of the 2016 AQMP includes a more 
detailed discussion of this methodology, and the Plan explains relevant 
differences between the two emissions estimates.
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    \37\ 2016 AQMP, approved by the EPA on September 16, 2020 (85 FR 
57714).
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    The Plan's emissions estimates are seasonally adjusted to summer 
emissions when ozone concentrations are highest. The Plan divides 
emissions into the four categories of ``point,'' ``area,'' ``on-road,'' 
and ``off-road'' sources, with point and area sources grouped as 
``stationary sources'' in summary tables. The base year for the 
emissions estimates is 2018. As Chapter 3 of the Plan explains, that 
data was projected to 2020 and 2023. Appendix I also contains full 
emissions breakdowns projected back to 2002 (the baseline year for the 
RFP demonstration), and forward to 2020 (a milestone year in the RFP 
demonstration) and 2023 (the attainment year). Table 1 compares 
emissions for 2002, 2018, 2020, and 2023.

                              Table 1--Coachella Valley NOX and VOC Emissions Inventory Summaries for 2002, 2018, and 2023
                                                 [Average summer weekday emissions in tons per day] \a\
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                                                                                      NOX                                         VOC
                            Category                             ---------------------------------------------------------------------------------------
                                                                     2002       2018       2020       2023       2002       2018       2020       2023
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Combined Point and Area Sources.................................       1.40       1.59       1.14       1.18       7.63       7.18       7.74       8.32
On-Road Mobile Sources..........................................      41.07      11.18       9.53       6.85      10.47       3.89       3.33       2.90
Other Mobile Sources............................................      11.77       5.56       5.10       4.30       4.76       3.30       3.23       3.22
                                                                 ---------------------------------------------------------------------------------------
    Totals......................................................      54.24      18.33      15.77      12.33      22.85      14.37      14.30      14.44
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\a\ Source: Coachella Valley Ozone Plan, Appendix I for 2002, Table 3-1 for 2018, and Table 3-2 for 2023.

    As described in the Plan, SCAQMD Rule 301 requires stationary 
sources emitting 4 tons per year (tpy) or more of NOX or VOC 
to report facility emissions directly to the District.
    Sources with NOX and VOC emissions below these 
thresholds are classified as area sources. The area source category 
includes aggregated emissions data from processes that are individually 
small and widespread. CARB and SCAQMD jointly estimate emissions for 
more than 400 area source categories. Appendix I of the Plan includes 
aggregate categories, such as consumer products, but not every 
individual category (e.g., hairspray). The Plan states that ``emissions 
from these sources are estimated using specific activity information 
and emission factors. Activity data are usually obtained from survey 
data or scientific reports, e.g., Energy Information Administration 
reports for fuel consumption other than natural gas fuel, Southern 
California Gas Company for natural gas consumption, paint supplier data 
under SCAQMD

[[Page 26822]]

Rule 314, `Fees for Architectural Coatings,' and District databases.'' 
\38\ Emission factors are values representing the amount of 
NOX or VOC per amount of fuel, hours of operation, or some 
other measurement. The Plan's emission factors are based on ``rule 
compliance factors, source tests, manufacturer's product or technical 
specification data, default factors (mostly from AP-42, the EPA's 
published emission factor compilation), or weighted emission factors 
derived from the point source facilities' annual emissions reports.'' 
\39\ Area source emissions are based on emissions projections for 2018 
and 2023 from the 2016 AQMP, ``using growth and control factors derived 
from regulatory and socio-economic data.'' \40\
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    \38\ Id.
    \39\ Id. at 3-2.
    \40\ Id.
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    For on-road mobile source emissions, which consists of emissions 
from trucks, automobiles, buses, and motorcycles, the Plan uses the 
vehicle activity from the ``2016-2040 Regional Transportation Plan/
Sustainable Communities Strategy'' (``2016-2040 RTP/SCS'') developed by 
the Southern California Association of Governments (SCAG). The Plan's 
mobile source emission factors come from CARB's 2017 emissions factor 
model, known as ``EMFAC2017,'' which was the latest model available for 
estimating on-road motor vehicle emissions in California at the time of 
its submission.\41\
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    \41\ EMFAC is short for EMission FACtor. The EPA announced the 
availability of the EMFAC2017 model for use in state implementation 
plan development and transportation conformity in California on 
August 15, 2019. 84 FR 41717. The EPA's approval of the EMFAC2017 
emissions model for SIP and conformity purposes was effective on the 
date of publication of the notice in the Federal Register.
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    The Plan also contains off-road NOX and VOC inventories 
developed by CARB using category-specific methods and models.\42\ The 
off-road mobile source category includes aircraft, trains, ships, and 
off-road vehicles and equipment used for construction, farming, 
commercial, industrial, and recreational activities. The 2016 AQMP 
provides the growth factors used to project base year emissions for the 
off-road sources.\43\
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    \42\ Detailed information on CARB's off-road motor vehicle 
emissions inventory methodologies is found at: https://ww2.arb.ca.gov/msei-road-documentation.
    \43\ 2016 AQMP, Appendix III, pp. III-1-24 to III-1-27.
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    Future emissions forecasts are primarily based on demographic and 
economic growth projections provided by SCAG, and control factors 
developed by the District in reference to the 2018 base year. Growth 
factors used to project these baseline inventories are derived mainly 
from data obtained from SCAG.\44\
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    \44\ 2016 AQMP, 7-25, and Appendix III, p. III-2-6.
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3. Proposed Action on the Emissions Inventories
    We have reviewed the emissions inventories in the Coachella Valley 
Ozone Plan and the inventory methodologies used by the District and 
CARB for consistency with CAA section 182(a)(1) and EPA guidance. We 
find that the base year and projected attainment year inventories are 
comprehensive, accurate, and current inventories of actual and 
projected emissions of NOX and VOC in the Coachella Valley 
as of the date of the submittal. Accordingly, we propose to find that 
these inventories provide an appropriate basis for the various other 
elements of the Coachella Valley Ozone Plan, including the RACM, ROP, 
RFP, and attainment demonstrations. The technical support document 
(TSD) accompanying this proposed rulemaking identifies SCAQMD rules 
submitted to the EPA for SIP approval after submittal of the Coachella 
Valley Ozone Plan and compares emissions in the Plan with emissions in 
the previously approved Severe attainment plan.\45\
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    \45\ EPA, Region IX, ``Technical Support Document, Approval and 
Promulgation of Implementation Plans; State of California; Coachella 
Valley; Extreme Attainment Plan for 1997 8-Hour Ozone Standards, 
Docket: EPA-R09-OAR-2023-0448, Additional Supporting Information for 
Notice of Proposed Rulemaking,'' March 2024.
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B. Reasonably Available Control Measures Demonstration and Adopted 
Control Strategy

1. RACM Requirements
    CAA section 172(c)(1) requires that each attainment plan provide 
for the implementation of all reasonable available control measures as 
expeditiously as practicable and provide for attainment of the NAAQS. 
The RACM demonstration requirement is a continuing applicable 
requirement for the Coachella Valley under the EPA's anti-backsliding 
rules that apply for revoked standards.\46\
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    \46\ See 40 CFR 51.1105(a)(1) and 51.1100(o)(17).
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    The EPA has previously provided guidance interpreting the RACM 
requirement in the ``General Preamble for the Implementation of Title I 
of the Clean Air Act Amendments of 1990'' (``General Preamble'') \47\ 
and in a memorandum entitled ``Guidance on Reasonably Available Control 
Measures (RACM) Requirements and Attainment Demonstration Submissions 
for the Ozone NAAQS,'' John Seitz, November 30, 1999 (``Seitz Memo''). 
In summary, EPA guidance provides that to address the requirement to 
adopt all RACM, states should consider all potentially reasonable 
control measures for source categories in the nonattainment area to 
determine whether they are reasonably available for implementation in 
that area and whether they would, if implemented individually or 
collectively, advance the area's attainment date by one year or 
more.\48\
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    \47\ See 57 FR 13498, 13560 (April 16, 1992). The General 
Preamble describes the EPA's preliminary view on how we would 
interpret various SIP planning provisions in title I of the CAA as 
amended in 1990, including those planning provisions applicable to 
the 1-hour ozone standards. The EPA continues to rely on certain 
guidance in the General Preamble to implement the 8-hour ozone 
standards under title I.
    \48\ General Preamble at 13560; see also Memorandum dated 
December 14, 2000, from John S. Seitz, Director, Office of Air 
Quality Planning and Standards, to Regional Air Directors, 
``Additional Submission on RACM from States with Severe One-Hour 
Ozone Nonattainment Area SIPs.''
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    Any measures that are necessary to meet these requirements that are 
not already either federally promulgated, part of the SIP, or otherwise 
creditable in SIPs must be submitted in enforceable form as part of a 
state's attainment plan for the area. CAA section 172(c)(6) requires 
nonattainment plans to include enforceable emissions limitations, and 
such other control measures, means or techniques (including economic 
incentives such as fees, marketable permits, and auctions of emission 
rights), as well as schedules and timetables for compliance, as may be 
necessary or appropriate to provide for attainment of such standards in 
such area by the applicable attainment date.\49\
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    \49\ See also CAA section 110(a)(2)(A).
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    The purpose of the RACM analysis is to determine whether or not 
control measures exist that are economically and technically reasonable 
and that provide emissions reductions that would advance the attainment 
date for nonattainment areas. The EPA defines RACM as any potential 
control measure for application to point, area, on-road, and non-road 
emission source categories that: (1) is technologically feasible; (2) 
is economically feasible; (3) does not cause ``substantial widespread 
and long-term adverse impacts;'' (4) is not ``absurd, unenforceable, or 
impracticable;'' and (5) can advance the attainment date by at least 
one year.\50\
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    \50\ General Preamble at 13560.
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    For ozone nonattainment areas classified as Moderate or above, CAA 
section 182(b)(2) also requires implementation of RACT for all major 
sources of VOC and for each VOC source category for which the EPA has

[[Page 26823]]

issued a Control Techniques Guidelines document. CAA section 182(f) 
requires that RACT under section 182(b)(2) also apply to major 
stationary sources of NOX. In Extreme areas, a major source 
is a stationary source that emits or has the potential to emit at least 
10 tpy of VOC or NOX.\51\ Under the 1997 Ozone 
Implementation rule, states were required to submit SIP revisions 
meeting the RACT requirements of CAA sections 182(b)(2) and 182(f) no 
later than 27 months after designation for the 1997 8-hour ozone 
standards (September 15, 2006, for areas designated in April 2004) and 
to implement the required RACT measures no later than 30 months after 
that submittal deadline.\52\ The EPA has approved the Severe area RACT 
SIP for the SCAQMD for the 1997 ozone standards, which included rules 
applicable to the Coachella Valley.\53\ With the reclassification from 
Severe to Extreme nonattainment, the major source threshold shifts from 
25 tpy to 10 tpy, changing the NOX and VOC sources subject 
to the RACT requirements. While this action does not address the 
Coachella Valley's RACT demonstration, we will consider the rules in 
relevant RACT demonstrations as potentially addressing RACM 
demonstration requirements.
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    \51\ CAA section 182(d).
    \52\ See 40 CFR 51.912(a). Following the reclassification of the 
Coachella Valley to Extreme nonattainment for the 1997 8-hour ozone 
standards, the EPA established a deadline of February 14, 2021, for 
the State to submit SIP revisions addressing the CAA section 
182(b)(2) and 182(f) RACT requirements. 85 FR 2311, 2312 (January 
15, 2020).
    \53\ 73 FR 76947 (December 18, 2008).
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2. Control Strategy and RACM Demonstration in the Coachella Valley 
Ozone Plan
a. The District's Component of the RACM Demonstration
    The RACM demonstration begins on page 6-12 of the Coachella Valley 
Ozone Plan. The Plan's RACM demonstration builds on the SCAQMD's prior 
RACM demonstrations for the Coachella Valley and South Coast Air Basin 
for the 2008 ozone standards in the 2016 AQMP, which the EPA approved 
in 2020.\54\ The Plan supplements this demonstration by evaluating as 
potential RACM new rules put in place after the 2016 AQMP and rules for 
area sources. The SCAQMD compared its rules with rules from other air 
districts within California (i.e., the Sacramento Metropolitan Air 
Quality Management District, the San Joaquin Valley Air Pollution 
Control District, the Ventura County Air Pollution Control District, 
the Antelope Valley Air Quality Management District, and the Mojave 
Desert Air Quality Management District) and from air quality agencies 
in Delaware and Texas.
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    \54\ The Coachella Valley Ozone Plan incorrectly identifies the 
EPA's approval of the RACM demonstration as 82 FR 26854 (June 12, 
2017), but the actual approval was published at 85 FR 57714 
(September 16, 2020).
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    The evaluation of other districts' and states' rules for stationary 
and area sources did not identify any rules as potential RACM. In all 
but a few cases, SCAQMD rules were as stringent or more stringent than 
other rules. Where other rules were more stringent, the SCAQMD still 
determined that its rules provided RACM-level controls. For example, 
the VOC control efficiency of SCAQMD Rule 461, ``Organic Liquid 
Loading,'' is less stringent than another rule (i.e., 90 percent vs. 95 
percent), but actual operational control efficiency at SCAQMD 
facilities exceeded the higher (95 percent) limit. In another example, 
SCAQMD Rule 1162, ``Polyester Resin Operations,'' which regulates more 
than 15 different categories of wood product coatings, has a lower 
limit than another district for one category, high-solid stains (240 
grams per liter vs. 350 grams per liter), but ``for almost all 
categories, Rule 1136 is as stringent as the other agency's rule and 
provides RACM level of control for this source category.'' \55\
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    \55\ Coachella Valley Ozone Plan, Table 6-10 at p. 6-17.
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    The Plan also highlights rules and programs revised since the 
completion of the 2016 AQMP that are anticipated to achieve additional 
reductions when fully implemented as planned. Table 4-1 of the Plan 
shows these measures have collectively further reduced emissions by 6.3 
tons per day (tpd) of NOX and 2.3 tpd of VOC.\56\ These 
reductions would occur primarily in the South Coast Air Basin; however, 
as the Plan explains, the ozone air quality problems of the Coachella 
Valley are primarily caused by transported emissions from within the 
South Coast Air Basin. The TSD for this proposed rulemaking supplements 
the District's analysis with a discussion of rules adopted by the 
SCAQMD since the completion of the Coachella Valley Ozone Plan.
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    \56\ Table 4-1 does not total the emission reductions for all 
measures.
---------------------------------------------------------------------------

    The 2016 AQMP included several commitments for additional emissions 
reductions, such as for the applications of zero or near-zero 
NOX emissions appliances in the residential and commercial 
sectors (CMB-02), additional enhancement in reducing energy use in 
existing residential buildings (ECC-03), and co-benefits from existing 
residential and commercial building energy efficiency mandates (ECC-
02). Collectively, these measures are expected to achieve 2.6 tpd of 
NOX reductions by 2023 in the South Coast Air Basin.\57\ 
Consistent with the emissions reductions from new and recently revised 
rules, the benefits achieved are primarily expected in the South Coast 
Air Basin.
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    \57\ Coachella Valley Ozone Plan, p. 6-20.
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b. Local Jurisdiction Component of the RACM Demonstration
    With respect to on-road mobile sources, we note that SCAG is the 
designated metropolitan planning organization (MPO) for a large portion 
of southern California, including Coachella Valley, and SCAG's 
membership includes local jurisdictions within the Coachella Valley. 
For the 2016 AQMP, SCAG evaluated a list of possible transportation 
control measures (TCMs) as one element of the larger RACM evaluation 
for the plan. TCMs are, in general, measures designed to reduce 
emissions from on-road motor vehicles through reductions in VMT or 
traffic congestion.
    In our final actions on the Severe area RACM requirements for the 
Coachella Valley for the 1997 and 2008 8-hour ozone standards,\58\ we 
concluded that the evaluation processes undertaken by SCAG were 
consistent with the EPA's RACM guidance and found that there were no 
additional RACM, including no additional TCMs that would advance 
attainment of the 1997 8-hour ozone standards in the South Coast Air 
Basin.\59\ More recently, we came to the same conclusion with respect 
to RACM and TCMs for the South Coast in our action on the ozone portion 
of the SCAQMD's ``Final 2012 Air Quality Management Plan.'' \60\
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    \58\ 82 FR 26854 and 85 FR 57714.
    \59\ See also 81 FR 75764 (November 1, 2016) (proposed rule for 
1997 8-hour ozone standards).
    \60\ See 79 FR 29712, 29720 (May 23, 2014) (proposed rule); 79 
FR 52526 (September 3, 2014) (final rule).
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    Although TCMs are implemented in the upwind South Coast Air Basin 
area to meet CAA requirements, neither the SCAQMD nor CARB rely on 
implementation of any TCMs in the Coachella Valley to demonstrate 
implementation of RACM in the Coachella Valley Ozone Plan. The SCAQMD 
and CARB justify the absence of TCMs in the Coachella Valley by 
reference to the significant influence of pollutant transport from the 
South Coast Air Basin on ozone conditions in the Coachella Valley.\61\
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    \61\ See Coachella Valley Ozone Plan, p. 6-29.

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[[Page 26824]]

c. The Statewide Component of the RACM Demonstration
    CARB has primary responsibility for reducing emissions in 
California from new and existing on-road and off-road engines and 
vehicles, motor vehicle fuels, and consumer products. CARB has been a 
leader in the development of stringent control measures for on-road and 
off-road mobile sources, fuels, and consumer products. Because of this 
role, the Plan identifies CARB's 2016 State Strategy as a key component 
of the control strategy necessary to attain the State's ozone goals, 
which includes attaining the 1997 ozone NAAQS. The Plan states that 
California has received waivers and authorizations for over 100 
regulations and lists several recent examples, such as rules governing 
light-, medium-, and heavy-duty vehicles; off-road vehicles and 
engines; and other sources including motorcycles, recreational boats, 
off-road recreational vehicles, cargo handling equipment, and 
commercial harbor craft.\62\ The Plan highlights reductions achieved 
through ``more stringent engine emissions standards, in-use 
requirements, incentive funding, and other policies and initiatives'' 
since the EPA's 2019 approval of the South Coast Air Basin RACM 
demonstration for the 2008 ozone standards.\63\
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    \62\ Coachella Valley Ozone Plan, p. 6-26.
    \63\ Id. at 6-28 et seq.
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    The CARB portion of the RACM evaluation also covers consumer 
products. CARB regulates VOC emissions from more than 130 consumer 
products, with the most recent rule revisions in 2018. The federal 
regulations for consumer products were last amended in 1998.\64\ Since 
submittal of the Plan, CARB has submitted additional consumer product 
regulations for approval into the SIP, but EPA has yet to act on this 
submittal.\65\
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    \64\ Id. at 6-29.
    \65\ Letter dated April 25, 2023, from Steve S. Cliff, CARB, to 
Martha Guzman, EPA Region IX, transmitting 2021 amendments to CARB's 
consumer product regulations (submitted electronically April 25, 
2023).
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3. The EPA's Evaluation of the Control Strategy and RACM
    We find that the Coachella Valley Ozone Plan includes a thorough 
update of the District's RACM demonstration for the 2008 ozone 
standards from the 2016 AQMP that we previously approved in 2020.\66\ 
This updated demonstration focuses on new rules put in place by five 
California air districts and two states since completion of the 2016 
AQMP, and we propose to find that it demonstrates that the District's 
stationary source controls represent RACM for the 1997 8-hour ozone 
standards.
---------------------------------------------------------------------------

    \66\ 85 FR 57714.
---------------------------------------------------------------------------

    With respect to mobile sources, we find that CARB's current program 
addresses the full range of mobile sources in the South Coast Air Basin 
and Coachella Valley through regulatory programs for both new and in-
use vehicles. Moreover, we find that the process conducted by CARB to 
prepare the 2016 State Strategy was reasonably designed to identify 
additional available measures within CARB's jurisdiction, and that CARB 
has adopted those measures that are reasonably available. As noted in 
the TSD supporting this rulemaking, following submittal of the 2016 
State Strategy, CARB has continued to submit mobile source control 
measures, such as the Heavy-Duty Inspection and Maintenance Regulation, 
which expands the inspection of heavy-duty trucks beyond particulate 
matter emissions to include the equipment controlling NOX 
emissions.
    With respect to TCMs, we find that SCAG's process for identifying 
additional TCM RACM and conclusion that the TCMs being implemented in 
the South Coast Air Basin are inclusive of all TCM RACM to be 
reasonably justified and supported. For the 2016 AQMP, given the 
minimal and diminishing emissions benefits generally associated with 
TCMs, no combination of TCMs implemented in the Coachella Valley could 
have contributed to advancing the attainment date in the Coachella 
Valley, and no TCMs are reasonably available for implementation in the 
Coachella Valley for the purposes of meeting the RACM requirement.\67\
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    \67\ While not required for CAA purposes, the 2016-2040 RTP/SCS 
includes a list of projects for the Coachella Valley, some of which 
represent the types of projects often identified as TCMs, such as 
traffic signalization projects and bike lane projects. 2016-2040 
RTP/SCS, Appendix, ``Project List.''
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    Additionally, we find that CARB's consumer products program 
generally exceeds the controls in place throughout other areas of the 
country. The additional commitments included in the 2016 State Strategy 
further strengthen this program by achieving additional VOC reductions. 
Some of the committed measures have already been submitted to the EPA, 
including lower VOC emission limits for seven consumer product 
categories.\68\
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    \68\ Letter dated April 25, 2023, from Steve S. Cliff, CARB to 
Martha Guzman, EPA Region IX, transmitting 2021 amendments to CARB's 
consumer product regulations (submitted electronically April 25, 
2023).
---------------------------------------------------------------------------

    While the Plan does not quantify the amount of reductions necessary 
to advance attainment by one year, in view of the current timing of 
this proposed approval, the Coachella Valley no longer has a practical 
opportunity to advance attainment prior to 2023. Therefore, the EPA is 
proposing to find that the Coachella Valley Ozone Plan provides for 
implementation of all RACM necessary to demonstrate expeditious 
attainment of the 1997 8-hour ozone standards in the Coachella Valley, 
consistent with the applicable requirements of CAA section 172(c)(1) 
and 40 CFR 51.1105(a)(1) and 51.1100(o)(17).

C. Attainment Demonstration

1. Statutory and Regulatory Requirements
    CAA section 182(c)(2)(A) requires that a plan for an ozone 
nonattainment area classified Serious or above include a 
``demonstration that the plan . . . will provide for attainment of the 
ozone [NAAQS] by the applicable attainment date. This attainment 
demonstration must be based on photochemical grid modeling or any other 
analytical method determined . . . to be at least as effective.'' The 
attainment demonstration predicts future ambient concentrations for 
comparison to the NAAQS, making use of available information on 
measured concentrations, meteorology, and current and projected 
emissions inventories of ozone precursors, including the effect of 
control measures in the Plan.
    In accordance with 40 CFR 51.903(a), areas classified Extreme for 
the 1997 ozone NAAQS must demonstrate attainment as expeditiously as 
practicable, but no later than 20 years after the effective date of 
designation to nonattainment. The Coachella Valley was designated 
nonattainment for the 1997 ozone NAAQS effective June 15, 2004,\69\ and 
accordingly, the area must demonstrate attainment of the standards by 
June 15, 2024. An attainment demonstration must show attainment of the 
standards by the calendar year prior to the attainment date, so in 
practice, Extreme nonattainment areas must demonstrate attainment in 
2023.
---------------------------------------------------------------------------

    \69\ 69 FR 23858.
---------------------------------------------------------------------------

    The EPA's recommended procedures for modeling ozone as part of an 
attainment demonstration are contained in ``Modeling Guidance for 
Demonstrating Air Quality Goals for Ozone, PM2.5, and 
Regional Haze,'' EPA 454/R-18-009, November 2018

[[Page 26825]]

(``Modeling Guidance'').\70\ The Modeling Guidance includes 
recommendations for a modeling protocol, model input preparation, model 
performance evaluation, use of model output for the numerical NAAQS 
attainment test, and modeling documentation. Air quality modeling is 
performed using meteorology and emissions from a base year, and the 
predicted concentrations from this base case modeling are compared to 
air quality monitoring data from that year to evaluate model 
performance.
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    \70\ The EPA modeling guidance is available on the EPA website 
at: https://www.epa.gov/scram/state-implementation-plan-sip-attainment-demonstration-guidance; direct link: https://www3.epa.gov/ttn/scram/guidance/guide/O3-PM-RH-Modeling_Guidance-2018.pdf. Additional EPA modeling guidance can be found in 40 CFR 51 
Appendix W, ``Guideline on Air Quality Models,'' 82 FR 5182 (January 
17, 2017); available at https://www.epa.gov/scram/clean-air-act-permit-modeling-guidance.
---------------------------------------------------------------------------

    Once the model performance is determined to be acceptable, future 
year emissions are simulated with the model. The relative (or percent) 
change in modeled concentrations due to future emissions reductions 
provides a relative response factor (RRF). Each monitoring site's RRF 
is applied to its monitored base period design value to provide the 
future design value for comparison to the NAAQS. The Modeling Guidance 
also recommends supplemental air quality analyses, which may be used as 
part of a weight of evidence (WOE) analysis. A WOE analysis 
corroborates the attainment demonstration by considering evidence other 
than the main air quality modeling attainment test, such as trends and 
additional monitoring and modeling analyses.
    The Modeling Guidance also does not require a particular year to be 
used as the base year for 1997 8-hour ozone plans.\71\ The Modeling 
Guidance states that the most recent year of the National Emissions 
Inventory may be appropriate for use as the base year for modeling, but 
that other years may be more appropriate when considering meteorology, 
transport patterns, exceptional events, or other factors that may vary 
from year to year.\72\ Therefore, the base year used for the attainment 
demonstration need not be the same year used to meet the requirements 
for emissions inventories and RFP.
---------------------------------------------------------------------------

    \71\ Modeling Guidance, 35.
    \72\ Id.
---------------------------------------------------------------------------

    With respect to the list of adopted measures, CAA section 172(c)(6) 
requires that nonattainment area plans include enforceable emissions 
limitations, and such other control measures, means or techniques 
(including economic incentives such as fees, marketable permits, and 
auctions of emission rights), as well as schedules and timetables for 
compliance, as may be necessary or appropriate to provide for timely 
attainment of the NAAQS.\73\
---------------------------------------------------------------------------

    \73\ See also CAA section 110(a)(2)(A).
---------------------------------------------------------------------------

2. Summary of the State's Submission
a. Photochemical Modeling
    Chapter 5 of the Coachella Valley Ozone Plan includes a description 
of photochemical modeling performed by the SCAQMD for the 1997 8-hour 
ozone standards. The modeling relies on a 2018 model base year and 
projects design values to demonstrate attainment of the 1997 ozone 
NAAQS in 2023.
    Chapter 5, ``Future Air Quality,'' of the Plan, includes a 
description of current air quality in the Coachella Valley, a summary 
of the ozone modeling approach, a model performance evaluation, results 
of the NAAQS attainment test, an unmonitored area analysis, an 
assessment of ozone sensitivity to NOX and VOC reductions, 
and a WOE analysis. The Plan uses the same approach that is outlined in 
more detail in the 2016 AQMP, with some updates to the modeling 
platform, input databases, and emissions inventories. Like the 2016 
AQMP, the Plan uses the EPA recommended Community Multiscale Air 
Quality Modeling System (CMAQ, version 5.0.2) modeling platform. An 
overview of the modeling approach and modeling protocol can be found in 
the 2016 AQMP, Appendix V, ``Modeling and Attainment Demonstrations,'' 
Chapter 1, ``Modeling Overview,'' and Chapter 2 ``Modeling Protocol.'' 
While the 2016 AQMP used 2012 as the model base year, the Plan uses 
2018 as the model base year on which to develop meteorological 
conditions and emissions inventories. Meteorological fields were 
developed for 2018 using the Weather Research and Forecasting Model 
(WRF, version 4.0.3) from the National Center for Atmospheric Research. 
Input information and model evaluation for WRF version 4.03 can be 
found in the SCAQMD, ``Final 2022 Air Quality Management Plan,'' 
adopted December 2, 2022 (``2022 AQMP''), Appendix V, Chapter 3, 
``Meteorological Modeling and Sensitivity Analyses.''
    CMAQ and WRF are both recognized in the Modeling Guidance as 
technically sound, state-of-the-art models. The areal extent and the 
horizontal and vertical resolution used in these models is adequate for 
modeling Coachella Valley ozone. The WRF modeling uses routinely 
available meteorological and air quality data collected during 2018. 
Those data cover May through September, a period that spans the period 
of highest ozone concentrations in the Coachella Valley. The District 
evaluated the WRF model performance and concluded that the WRF 
simulation for 2018 provided representative meteorological fields that 
well characterized the observed conditions. The District's conclusions 
were supported by statistical metrics and hourly time series plots of 
water vapor mixing ratio, wind speed, direction, and temperature for 
the southern California domain as well an evaluation of the predicted 
planetary boundary layer height and the coast-to-inland temperature 
gradient.
    Ozone model performance statistics are described in the Coachella 
Valley Ozone Plan at Chapter 5.\74\ This chapter includes a table of 
statistics recommended in the Modeling Guidance and hourly ozone time 
series plots for 2018. The hourly time series and statistics show 
generally good model performance, though many individual daily ozone 
peaks are underpredicted.\75\ Note that, because only relative changes 
are used from the modeling, the underprediction of ozone concentrations 
does not mean that future concentrations will be underestimated.
---------------------------------------------------------------------------

    \74\ Coachella Valley Ozone Plan, Chapter 5, 5-4--5-5.
    \75\ Coachella Valley Ozone Plan, Figure 5-2.
---------------------------------------------------------------------------

    After model performance for the 2018 base case was accepted, the 
model was applied to develop RRFs for the attainment demonstration. 
This entailed running the model with the same meteorological inputs as 
before, but with adjusted emissions inventories to reflect the expected 
changes between 2018 and the 2023 attainment year. The base year or 
``reference year'' modeling inventory was the same as the inventory for 
the modeling base case. The 2023 inventory projects the base year into 
the future by including the effect of economic growth and emissions 
control measures. The set of 153 days from May 1 through September 30, 
2018, was simulated and analyzed to determine 8-hour average maximum 
ozone concentrations for the 2018 and 2023 emissions inventories. To 
develop the RRFs for the 1997 8-hour ozone standards, only the top 10 
days were used, consistent with the Modeling Guidance.\76\
---------------------------------------------------------------------------

    \76\ Modeling Guidance, section 4.2.1.
---------------------------------------------------------------------------

    The Modeling Guidance addresses attainment demonstrations with 
ozone NAAQS based on 8-hour averages and for the 1997 ozone NAAQS the

[[Page 26826]]

Coachella Valley Ozone Plan carries out the attainment test procedure 
consistent with the Modeling Guidance. The RRFs are calculated as the 
ratio of future to base year concentrations; these were then applied to 
weighted base year design values for each monitor to arrive at future 
year design values.\77\ Ozone is measured continuously at two locations 
in the Coachella Valley at the Palm Springs and Indio air monitoring 
stations. The modeled 2023 ozone design value at the Palm Springs site 
(the higher of the two sites) is 0.0832 ppm; this value demonstrates 
attainment of the 1997 ozone NAAQS.\78\
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    \77\ The Modeling Guidance recommends that RRFs be applied to 
the average of three 3-year design values centered on the base year. 
For a 2018 base year, recommended design values would be 2016-2018, 
2017-2019, and 2018-2020. This amounts to a 5-year weighted average 
of individual year 4th high concentrations, centered on the base 
year of 2018, and so is referred to as a weighted design value. The 
Coachella Valley Ozone Plan was adopted in December 2020, before 
2020 monitoring data was available, so the Plan instead uses design 
values for 2015-2017, 2016-2018, and 2017-2019.
    \78\ Coachella Valley Ozone Plan, 5-6.
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    The Plan modeling includes an ``Unmonitored Area Analysis'' (UAA) 
to assess whether locations without a monitor can reach attainment; the 
standard attainment test procedure covers only locations with a 
monitor. A UAA is recommended in the Modeling Guidance, but not 
required in the 1997 Ozone Implementation Rule--Phase 2.\79\ Consistent 
with EPA Guidance, the District calculated five-year weighted design 
values for all monitoring stations that meet EPA's data quality 
requirements within the modeling domain and spatially interpolated 
concentrations for the area between the design values. RRFs were then 
applied to the interpolated measurement field to calculate future year 
design values. The District asserts that when all valid ozone design 
values were interpolated, they were too sparsely populated near the 
boundary of Coachella Valley to reasonably guide design value contours. 
To compensate, the District excluded the Morongo monitor and added 
several pseudo-monitors throughout the domain to guide the 
interpolation.\80\ With these modifications the predicted future design 
values are all below the level of the 1997 8-hour ozone standards 
throughout the domain.
---------------------------------------------------------------------------

    \79\ 70 FR 71612.
    \80\ Coachella Valley Ozone Plan, p. 5-6.
---------------------------------------------------------------------------

    In addition to the formal attainment demonstration, the Plan also 
contains a WOE demonstration that includes ambient ozone data and 
trends and a sensitivity analysis using CMAQ 5.3.1, a later version of 
the model to complement the regional photochemical modeling analyses.
b. Control Strategy
    The control strategy for attainment of the 1997 ozone NAAQS in the 
Coachella Valley relies primarily on timely attainment in 2023 of the 
1997 ozone NAAQS in the South Coast Air Basin. As described in the 
Coachella Valley Ozone Plan and in Section I.B of this document, the 
primary cause of ozone in the Coachella Valley is the transport of 
ozone and its precursors from the South Coast Air Basin.
    Because ozone concentrations at the Palm Springs monitor--the only 
monitoring site currently exceeding the 8-hour 1997 ozone NAAQS--are 
more sensitive to changes in NOX than VOCs,\81\ the Plan's 
control strategy relies on NOX reductions and limited VOC 
reductions. Since the EPA's promulgation of the 1997 ozone NAAQS, 
NOX emissions in the South Coast Air Basin have declined by 
76 percent.\82\ Mobile sources, responsible for 80 percent of regional 
NOX emissions, are the primary focus of future emissions 
reductions.
---------------------------------------------------------------------------

    \81\ Coachella Valley Ozone Plan, p. 5-8 and Figure 5-5.
    \82\ Coachella Valley Ozone Plan, p. 4-1.
---------------------------------------------------------------------------

    A thorough discussion of the SCAQMD's control strategy for the 
Coachella Valley appears in the 2016 AQMP. The 2016 AQMP provides the 
District's control strategy through the 2026 attainment year for the 
2008 ozone standards. The Coachella Valley Ozone Plan provides an 
update to that discussion, specifically focusing on the measures 
implemented after the 2016 AQMP that result in emissions reductions by 
2023.
    The South Coast Air Basin control strategy for the 1997 ozone NAAQS 
relies on emissions reductions from already-adopted measures, 
commitments by the District to certain regulatory and nonregulatory 
initiatives and aggregate emissions reductions, and commitments by 
SCAQMD and CARB to certain regulatory and nonregulatory initiatives and 
aggregate emissions reductions. In the 2016 AQMP, already-adopted 
measures are expected to achieve approximately 66 percent of the 
NOX reductions needed from a 2012 base year for the South 
Coast Air Basin to attain the 1997 ozone NAAQS in 2023. To address the 
remaining emissions reductions, which are shown in Table 2, the 2016 
AQMP included District and CARB aggregate commitments to achieve 
additional emissions reductions by 2023. These reductions are discussed 
in the EPA's proposed approval of the 2016 AQMP for the South Coast Air 
Basin.\83\
---------------------------------------------------------------------------

    \83\ 84 FR 28132 (June 17, 2019), Sections III.D.2.B.i and ii.

 Table 2--District and CARB Aggregate Emission Reduction Commitments for
                                  2023
                                  [tpd]
------------------------------------------------------------------------
                  Plan                          NOX             VOC
------------------------------------------------------------------------
SCAQMD \a\..............................              23               6
CARB \b\................................             113           50-51
                                         -------------------------------
    Total...............................             136           56-57
------------------------------------------------------------------------
\a\ Source: 2016 AQMP at Table 4-10.
\b\ Source: 2016 AQMP at Table 4-5.

    The Plan updates this analysis to incorporate more recent SCAQMD 
and CARB rules and programs that continue to achieve emissions 
reductions in future baseline emissions for both the South Coast Air 
Basin and Coachella Valley. For SCAQMD, the revised regulations are 
Regulation XX, ``RECLAIM Program;'' Rule 1111, ``Reduction of 
NOX Emissions form Natural-Gas-Fired, Fan-Type Central 
Furnaces,'' and the CLEANair Furnace Rebate Program; Rule 1146.2, 
``Large Water Heater, Small Boilers and Process Heaters;'' and Rule 
1147, ``NOX Reductions from Miscellaneous Sources.'' The 
District's incentive programs include the Carl Moyer Memorial Air 
Quality Standards Attainment Program to retrofit and replace heavy-duty 
diesel engines;

[[Page 26827]]

Clean School Buses Incentives; and the Surplus Off-Road Opt-In for 
NOX Program for low emission heavy duty engines for off-road 
diesel fleets.\84\ For CARB, the regulations that continue to result in 
improved future emissions estimates include the Advanced Clean Cars 
program, the Truck and Bus Regulation, and the In-Use Large Spark 
Ignition Fleet Regulation.\85\
---------------------------------------------------------------------------

    \84\ Coachella Valley Ozone Plan, pp. 4-2 to 4-4.
    \85\ The complete list of incentive programs is provided on 
pages 4-3 to 4-4 of the Coachella Valley Ozone Plan.
---------------------------------------------------------------------------

    The Plan also highlights rules and programs that continue to 
achieve reductions that have not been factored into the future 
emissions estimates for SCAQMD and CARB. SCAQMD efforts include Rule 
1117, ``Emissions of Oxides of Nitrogen form Glass Melting Furnaces;'' 
Rule 1134, ``Emissions of Oxides from Stationary Gas Turbines''; Rule 
1135, ``Emissions of Oxides of Nitrogen from Electricity Generating 
Facilities;'' and facility-based mobile source measures covering marine 
ports railyards, warehouse/distribution centers, commercial 
developments and new developments and redevelopment projects.\86\ Table 
4-1 shows estimated reductions for these rules and facility-based 
mobile source measures. Some of the measures continue to increase 
reductions in future years, including adopted CARB regulations not 
reflected in the future emissions estimate such as the Innovative Clean 
Transit Regulation; the Zero-Emission Airport Shuttle Regulation; the 
Advanced Clean Truck regulation and the Omnibus Low-NOX 
Regulation. All measures that achieve further emissions reduction and 
not reflected in the future 2023 emissions estimate serve to increase 
the likelihood that the Coachella Valley attains the 1997 ozone NAAQS.
---------------------------------------------------------------------------

    \86\ Id. at 4-4 to 4-6.
---------------------------------------------------------------------------

c. Attainment Demonstration
    Chapter 5 of the Coachella Valley Ozone Plan describes the 
Coachella Valley's progress toward attaining the 1997 ozone standards. 
The Plan summarizes the District's modeling for the area and concludes 
that the measures included in the control strategy (including CARB 
commitments) will result in the area attaining the standards no later 
than 2023. The WOE discussion provides additional discussion of air 
quality trends and projections in the Coachella Valley and determines 
that the area is on track to attain the 1997 ozone NAAQS by 2023.
3. The EPA's Review of the State's Submission
a. Photochemical Modeling
    As discussed in Section III.A of this document, we are proposing to 
approve the base year emissions inventory for the attainment 
demonstration and to find that the future year emissions projections in 
the Coachella Valley Ozone Plan reflect appropriate calculation methods 
and that the latest planning assumptions are properly supported by SIP-
approved stationary source and mobile source measures. The Plan employs 
the modeling protocol from the 2016 AQMP, and Appendix V of that 
document in particular, with updates to the modeling platform, input 
databases, and emissions inventory.\87\ The discussion below addresses 
modeling information included in both the Plan and the 2016 AQMP. 
Because of the importance of ozone transport from the South Coast to 
attainment in the Coachella Valley, and the close interactions of the 
modeling for each area, we have considered the modeling for both the 
Coachella Valley and the South Coast Air Basin. Similar and additional 
discussion for the South Coast Air Basin can be found in our June 17, 
2019 proposed action on the 2016 AQMP.\88\
---------------------------------------------------------------------------

    \87\ Coachella Valley Ozone Plan, p. 5-2 and 5-8.
    \88\ 84 FR 28132.
---------------------------------------------------------------------------

    Based on our review of the Coachella Valley Ozone Plan, the EPA 
finds that the photochemical modeling is adequate for purposes of 
supporting the attainment demonstration.\89\ First, we note the 
discussion of modeling procedures, tests, and performance analyses 
called for in the Modeling Protocol (i.e., 2016 AQMP, Appendix V, 
Chapter 2) and the good model performance (Coachella Valley Ozone Plan, 
Chapter 5). Second, we find the WRF meteorological model results and 
performance statistics, including hourly time series graphs of water 
vapor mixing ratio, wind speed, direction, and temperature for both the 
South Coast and the Coachella Valley, to be satisfactory and consistent 
with our Modeling Guidance.\90\ Performance was evaluated for the 
winter season (January, November, and December 2018) and summer season 
(June, July, and August 2018).\91\ Diurnal variation of temperature, 
humidity, and surface wind are well represented by WRF. Temperature and 
wind speed are more accurate in the summer season than in the winter 
months. The observed temperature gradient from the coast to inland was 
well characterized by WRF. Both the observational data and WRF 
simulation showed distinct diurnal variations in wind speed in the 
summer, with a strong sea breeze in the afternoon responsible for 
transport inland. In general, the WRF simulations reproduce the 
dominant wind direction as the measurement at each station. The diurnal 
cycle in PBL height was well captured by the simulations. Overall, the 
daily WRF simulation for 2018 provided representative meteorological 
fields that characterized the observed conditions well.
---------------------------------------------------------------------------

    \89\ The EPA's review of the modeling and attainment 
demonstration is discussed in greater detail in section V of the TSD 
for this action (``Modeling and Attainment Demonstration'').
    \90\ Modeling Guidance, 30.
    \91\ Temperature, water vapor mixing ratio, and wind speed were 
evaluated in terms of normalized gross bias and normalized gross 
error.
---------------------------------------------------------------------------

    The model performance statistics for ozone are described in Chapter 
5 of the Plan and are based on the statistical evaluation recommended 
in the Modeling Guidance. Model performance was provided for 8-hour 
daily maximum ozone in the nonattainment area. As noted in Section 
IV.C.2.a of this document, the statistics and hourly time series show 
generally good performance, and while many individual daily ozone peaks 
are underpredicted, this does not mean that future concentrations based 
on monitored data and modeled RRFs will be underestimated. In addition, 
the WOE analysis presented provides additional information with respect 
to the observational trends and further supports the model performance.
    Notwithstanding the general sufficiency of the modeling, we find 
that the Plan's UAA analysis does not provide justification for 
excluding the Morongo monitor or for adding pseudo-monitors to alter 
the interpolation. We therefore conclude the UAA is not sufficiently 
supported, and we are not evaluating those results here. However, we 
conclude that based on the density of the ozone monitoring stations 
within the Coachella Valley and upwind, as well as the uncertainty in 
the interpolation due to complex topography, the attainment 
demonstration is adequately supported without a UAA. We recommend that 
CARB and SCAQMD evaluate the continuing adequacy of the existing 
monitors as part of their ambient air monitoring network 5-year network 
assessment.
    The modeling shows that existing control measures from CARB and the 
District, together with the commitments in the 2016 AQMP and further 
updated in the Coachella Valley Ozone Plan, are sufficient to attain 
the 1997 8-hour ozone standards by 2023 at all monitoring sites in the 
Coachella Valley.

[[Page 26828]]

We are proposing to find the air quality modeling adequate to support 
the attainment demonstration for the 1997 ozone NAAQS, based on 
reasonable meteorological and ozone modeling performance, and supported 
by the WOE analysis.
    For additional information, please see the TSD for this action.
b. Control Strategy
    The control strategy in the Coachella Valley Ozone Plan relies 
primarily on previously adopted and future emissions reductions 
detailed in the 2016 AQMP. As described in Section IV.C.2.b of this 
document, a significant portion of the emissions reductions needed to 
attain the 1997 ozone NAAQS in the South Coast by 2023 will be obtained 
through previously adopted measures in the SIP, and the balance of the 
reductions needed for attainment will result from enforceable 
commitments to take certain specific actions within prescribed periods 
and to achieve aggregate tonnage reductions of VOC or NOX by 
specific years. The aggregate commitments provide the remaining 
additional upwind reductions necessary for the Coachella Valley to 
attain the 1997 ozone NAAQS in 2023. In our October 1, 2019 approval of 
the 2016 South Coast Ozone SIP, the EPA approved the control strategy 
to attain the 2008 ozone standards for the Coachella Valley by 2026, 
including CARB's and the District's aggregate commitments, for the 
South Coast to attain the 1997 ozone NAAQS.\92\
---------------------------------------------------------------------------

    \92\ 84 FR 52005.
---------------------------------------------------------------------------

    For the reasons described in that action and based on the 
District's demonstration specific to the Coachella Valley described in 
this section, we propose to find the District's control strategy 
acceptable for purposes of attaining the 1997 8-hour ozone standards in 
the Coachella Valley. For additional information, please see the TSD 
for this action.
c. Attainment Demonstration
    Based on our proposed determinations that the photochemical 
modeling and control strategy are acceptable, we propose to approve the 
attainment demonstration for the 1997 ozone NAAQS in the Coachella 
Valley Ozone Plan as meeting the requirements of CAA section 
182(c)(2)(A) and 40 CFR 51.1105(a)(1) and 51.1100(o)(12). This 
demonstration shows the area attaining the 1997 8-hour ozone standards 
by the outermost statutory attainment date of June 15, 2024.

D. Rate of Progress and Reasonable Further Progress Demonstrations

1. Rate of Progress
    For areas classified as Moderate or above, CAA section 182(b)(1) 
requires a SIP revision providing for ROP, defined as a one time, 15 
percent actual VOC emissions reduction during the six years following 
the baseline year 1990, or an average of 3 percent per year. While the 
ROP demonstration is a potentially applicable continuing applicable 
requirement, the EPA has already approved the 15 percent VOC only ROP 
demonstration for Coachella Valley for the 1997 8-hour ozone standards, 
so this requirement has been met.\93\
---------------------------------------------------------------------------

    \93\ 82 FR 26854.
---------------------------------------------------------------------------

2. Reasonable Further Progress
a. Requirements
    CAA sections 172(c)(2) and 182(b)(1) require plans for 
nonattainment areas to provide for RFP. RFP is defined in CAA section 
171(1) as ``such annual incremental reductions in emissions of the 
relevant air pollutant as are required by this part or may reasonably 
be required by the Administrator for the purpose of ensuring attainment 
of the applicable [NAAQS] by the applicable date.'' CAA section 
182(c)(2)(B) requires ozone nonattainment areas classified as Serious 
or higher to submit no later than 3 years after designation for the 
1997 8-hour ozone standards an RFP SIP providing for an average of 3 
percent per year of VOC and/or NOX emissions reductions for 
(1) the 6-year period immediately following the baseline year; and (2) 
all remaining 3-year periods after the first 6-year period out to the 
area's attainment date.\94\ The RFP requirement is a continuing 
applicable requirement for the Coachella Valley under the EPA's anti-
backsliding rules that apply once a standard has been revoked. See 40 
CFR 51.1105(a)(1) and 51.1100(o)(4).
---------------------------------------------------------------------------

    \94\ Following the reclassification of the Coachella Valley to 
Extreme nonattainment for the 1997 8-hour ozone standards, the EPA 
established a deadline of February 14, 2021, for the state to submit 
SIP revisions addressing the CAA section sections 172(c)(2) and 
182(b)(1) RFP requirements. 85 FR 2311, 2312.
---------------------------------------------------------------------------

    CAA section 182(c)(2)(C) allows for the substitution of 
NOX emissions reductions in place of VOC reductions to meet 
the RFP requirements. According to the EPA's NOX 
Substitution Guidance,\95\ the substitution of NOX 
reductions for VOC reductions must be done on a percentage basis, 
rather than a straight ton-for-ton exchange. There are two steps for 
substituting NOX for VOC. First, an equivalency 
demonstration must show that the cumulative RFP emissions reductions 
are consistent with the NOX and VOC emissions reductions 
determined in the ozone attainment modeling demonstration. Second, 
specified reductions in NOX and VOC emissions should be 
accomplished after the initial 6-year ROP reductions are achieved and 
before the attainment date, consistent with the continuous RFP emission 
reduction requirement.\96\
---------------------------------------------------------------------------

    \95\ EPA Office of Air Quality Planning and Standards, 
``NOX Substitution Guidance,'' December 1993.
    \96\ As noted in Section IV.D.1 of this document, Coachella 
Valley has already met the 15 percent ROP demonstration requirement.
---------------------------------------------------------------------------

    Section 182(b)(1) requires that reductions exclude emissions 
reductions from four prescribed federal programs (i.e., the federal 
motor vehicle control program, the federal Reid vapor pressure (RVP) 
requirements, any RACT corrections previously specified by the EPA, and 
any I/M program corrections necessary to meet the Basic I/M level); and 
(3) be calculated from an ``adjusted'' baseline relative to the year 
for which the reduction is applicable.
    The adjusted base year inventory must exclude the emissions 
reductions from fleet turnover between 1990 and 1996 and from federal 
RVP regulations promulgated by November 15, 1990, or required under 
section 211(h) of the Act. The net effect of these adjustments is that 
states are not able to take credit for emissions reductions that would 
result from fleet turnover of current federal-standard cars and trucks, 
or from already existing federal fuel regulations. However, the SIP can 
take full credit for the benefits of any post-1990 vehicle emissions 
standards, as well as any other new federal or state motor vehicle or 
fuel programs that will be implemented in the nonattainment area, 
including Tier 1 exhaust standards, new evaporative emissions 
standards, reformulated gasoline, Enhanced I/M, California low 
emissions vehicle program, transportation control measures, etc.
b. RFP Demonstration in the State Submittal
    The Coachella Valley Ozone Plan contains emissions estimates for 
the baseline, milestone, and attainment years.\97\ Tables 3 and 4 show 
the RFP demonstration.\98\ The RFP

[[Page 26829]]

demonstration calculates future year VOC targets from the 2002 
baseline, consistent with CAA 182(c)(2)(B)(i), which requires 
reductions of ``at least 3 percent of baseline emissions each year,'' 
and it substitutes NOX reductions for VOC reductions 
beginning in milestone year 2020 to meet VOC emission targets. The 
District concluded that RFP demonstration meets the applicable 
requirements for each milestone year as well as the attainment year.
---------------------------------------------------------------------------

    \97\ Coachella Valley Ozone Plan, pp. 6-1 to 6-7.
    \98\ The years between 2002 and 2020 were addressed in the 
``Staff Report, Proposed Updates to the 1997 8-Hour Ozone Standard, 
State Implementation Plans; Coachella Valley and Western Mojave 
Desert'' (``2014 SIP Update'') which covered the Coachella Valley's 
Severe area requirements for the 1997 ozone standards. 82 FR 26854.

                     Table 3--Calculation of RFP Demonstration for Coachella Valley--VOC \a\
----------------------------------------------------------------------------------------------------------------
                    VOC emission calculations                        2002 \b\        2020 \b\        2023 \b\
----------------------------------------------------------------------------------------------------------------
1. Baseline VOC (tpd)...........................................           22.85           14.30           14.44
2. Required Percent Reductions from Base Year (%)...............             n/a             51%             60%
3. Target VOC Level (tpd).......................................             n/a            11.2             9.1
4. Cumulative Milestone Year Shortfall (tpd)....................             n/a             3.1             5.3
5. Cumulative Shortfall in VOC (%)..............................             n/a           13.6%           37.1%
6. Incremental Milestone Year Shortfall (%).....................             n/a           13.6%           23.5%
----------------------------------------------------------------------------------------------------------------
\a\ Source: Table 6-1 of the Coachella Valley Ozone Plan.
\b\ Units are tons per day (summer planning) unless otherwise noted.


                     Table 4--Calculation of RFP Demonstration for Coachella Valley--NOX \a\
----------------------------------------------------------------------------------------------------------------
                    NOX emission calculations                        2002 \b\        2020 \b\        2023 \b\
----------------------------------------------------------------------------------------------------------------
1. Baseline NOX Emissions (tpd).................................           54.24           15.77           12.33
2. Reductions in NOX Emissions since Base Year (tpd)............             n/a           38.47           41.91
3. Percent Reductions in NOX Emissions since Base Year..........             n/a           70.9%           77.3%
4. Previous NOX Substitution (%)................................             n/a             n/a           13.6%
5. Percent Available for NOX Substitution (%)...................             n/a           70.9%           63.7%
6. Incremental Milestone Year VOC Shortfall (%).................             n/a           13.6%           23.5%
7. Percent Surplus Reduction (%)................................             n/a           57.3%           40.2%
8. RFP Compliance...............................................             n/a             Yes             Yes
----------------------------------------------------------------------------------------------------------------
\a\ Source: Table 6-2 of the Coachella Valley Ozone Plan. Table 4 of this document has been adapted from Table 6-
  2 to remove adjustments related to use of excess NOX emissions reductions to address the contingency measures
  requirements of CAA sections 179(c)(9) and 182(c)(9). Under the EPA's most recent guidance (described in
  Section IV.G.1 of this document), excess NOX reductions may not be used for this purpose.
\b\ Units are tons per day (summer planning) unless otherwise noted.

    CAA section 182(b)(1)(D) prohibits states from taking credit for 
certain categories of measures in an RFP demonstration. The three 
categories of non-creditable measures identified in CAA sections 
182(b)(1)(D)(iii)-(iv) achieved their reductions many years ago and 
reductions from these measures would have no effect for the RFP 
milestones modeled in the Plan.\99\ All categories of non-creditable 
emissions are considered de minimis for the 2008 or 2015 ozone NAAQS 
(and therefore do not need to be calculated as part of in an RFP 
demonstration for these standards).\100\ While emissions from the 
category identified in CAA section 182(b)(1)(D)(i) (``any measure 
relating to motor vehicle exhaust or evaporative emissions promulgated 
by the Administrator by January 1, 1990'') affect the demonstration for 
the 1997 8-hour ozone standards, the change in this effect becomes 
smaller with each successive milestone year. CARB has provided 
estimates for non-creditable emissions, which are less than 10 percent 
of the base year inventory. For more information about the correction 
to the non-creditable reductions in the 2014 SIP Update, including a 
revised RFP demonstration, see the TSD supporting this proposed rule.
---------------------------------------------------------------------------

    \99\ 80 FR 12264, 12274.
    \100\ 40 CFR 51.1110(a)(7) and 51.1310(a)(7).
---------------------------------------------------------------------------

3. Proposed Action on the ROP and RFP Demonstrations
    As noted in Section IV.D.1 of this document, the EPA has already 
approved a 15-percent ROP plan for the Coachella Valley in our prior 
action on SCAQMD's submittal for the 1997 ozone NAAQS; \101\ therefore, 
we find that the District and CARB have met the ROP requirement for 
this area.
---------------------------------------------------------------------------

    \101\ 82 FR 26854.
---------------------------------------------------------------------------

    Based on our review of the emissions inventory documentation in the 
Coachella Valley Ozone Plan, we find that CARB and the District have 
used the most recent planning and activity assumptions, emissions 
models, and methodologies in developing the RFP baseline and milestone 
year emissions inventories, and that the District and CARB have used an 
appropriate calculation method to demonstrate RFP. For these reasons, 
we have determined that the Plan demonstrates RFP in the 2023 
attainment year, consistent with applicable CAA requirements and EPA 
guidance. We therefore propose to approve the Extreme RFP demonstration 
for the Coachella Valley for the 1997 ozone NAAQS under CAA sections 
172(c)(2), 182(b)(1) and 182(c)(2) and 40 CFR 51.1105(a)(1) and 
51.1100(o)(4).

E. Vehicle Miles Travelled Offset Demonstration

1. Requirements for a VMT Offset Demonstration
    CAA section 182(d)(1)(A) requires a state to submit a revision for 
each area classified as Severe or above to identify and adopt specific 
enforceable transportation control strategies (TCSs) and TCMs to offset 
growth in emissions from growth in VMT or numbers of vehicle trips in 
such area. CAA section 182(d)(1)(A) also requires the SIP to attain 
reductions in motor vehicle emissions consistent with RFP 
demonstrations; and to implement measures as necessary to demonstrate 
attainment. We refer to CAA section 182(d)(1)(A) as the ``VMT offset 
requirement.'' The VMT offset requirement is a continuing applicable 
requirement for the Coachella Valley under the EPA's anti-backsliding 
rules

[[Page 26830]]

that apply once a standard has been revoked.\102\
---------------------------------------------------------------------------

    \102\ 40 CFR 40 CFR 51.1105(a)(1) and 51.1100(o)(10).
---------------------------------------------------------------------------

    In response to the Ninth Circuit Court of Appeals' decision in 
Association of Irritated Residents v. EPA,\103\ we issued a memorandum 
titled ``Implementing Clean Air Act Section 182(d)(1)(A): 
Transportation Control Measures and Transportation Control Strategies 
to Offset Growth in Emissions Due to Growth in Vehicle Miles 
Travelled'' (``August 2012 Guidance'').\104\ The August 2012 Guidance 
discusses the meaning of the terms TCSs and TCMs, and recommends that 
both TCSs and TCMs be included in the emissions calculations made for 
the purpose of determining the degree to which any hypothetical growth 
in emissions due to growth in VMT should be offset. Generally, TCS is a 
broad term that encompasses many types of controls (including, for 
example, motor vehicle emissions limitations, I/M programs, alternative 
fuel programs, other technology-based measures, and TCMs) that would 
fit within the regulatory definition of ``control strategy.'' \105\ TCM 
is defined at 40 CFR 51.100(r) to mean ``any measure that is directed 
toward reducing emissions of air pollutants from transportation 
sources,'' including, but not limited to, measures listed in CAA 
section 108(f), and generally refers to programs intended to reduce the 
VMT, the number of vehicle trips, or traffic congestion, such as 
programs for improved public transit, designation of certain lanes for 
passenger buses and high-occupancy vehicles, trip reduction ordinances, 
and similar measures.
---------------------------------------------------------------------------

    \103\ 632 F.3d. 584, 596-597 (9th Cir. 2011), reprinted as 
amended on January 27, 2012, 686 F.3d 668, further amended February 
13, 2012 (ruling additional TCMs are required whenever vehicle 
emissions are projected to be higher than they would have been had 
VMT not increased, even when aggregate vehicle emissions are 
actually decreasing).
    \104\ EPA, Office of Transportation and Air Quality, 
``Implementing Clean Air Act Section 182(d)(1)(A): Transportation 
Control Measures and Transportation Control Strategies to Offset 
Growth in Emissions Due to Growth in Vehicle Miles Travelled,'' EPA-
420-B-12-053, August 2012.
    \105\ See, e.g., 40 CFR 51.100(n).
---------------------------------------------------------------------------

    The August 2012 Guidance also explains how states may demonstrate 
that the VMT offset requirement is satisfied in conformance with the 
Court's ruling. In the approach recommended by the August 2012 
Guidance, states develop one emission inventory estimate for the base 
year, and three different emissions inventory scenarios for the 
attainment year. Two of these scenarios would represent hypothetical 
emissions scenarios that would provide the basis to identify the 
``growth in emissions'' due solely to the growth in VMT, and one that 
would represent projected actual motor vehicle emissions after fully 
accounting for projected VMT growth and offsetting emissions reductions 
obtained by all creditable TCSs and TCMs. The August 2012 Guidance 
contains specific details on how states might conduct the calculations.
    The base year on-road VOC emissions inventory should be based on 
VMT in that year, and it should reflect all enforceable TCSs and TCMs 
in place in the base year. This would include vehicle emissions 
standards, state and local control programs such as I/M programs or 
fuel rules, and any additional implemented TCSs and TCMs that were 
already required by or credited in the SIP as of the base year.
    The first of the emissions calculations for the attainment year 
would be based on the projected VMT and trips for that year and assume 
that no new TCSs or TCMs beyond those already credited in the base year 
inventory have been put in place since the base year. This calculation 
demonstrates how emissions would hypothetically change if no new TCSs 
or TCMs were implemented, and VMT and trips were allowed to grow at the 
projected rate from the base year. This estimate would show the 
potential for an increase in emissions due solely to growth in VMT and 
trips, representing a no action scenario. Emissions in the attainment 
year in this scenario may be lower than those in the base year due to 
fleet turnover to lower-emitting vehicles. Emissions may also be higher 
if VMT and/or vehicle trips are projected to sufficiently increase in 
the attainment year.
    The second of the attainment year emissions calculations would also 
assume that no new TCSs or TCMs beyond those already credited have been 
put in place since the base year and would also assume no growth in VMT 
and trips between the base year and attainment year. Like the no-action 
attainment year estimate described previously, emissions in the 
attainment year may be lower than those in the base year due to fleet 
turnover, but the emissions would not be influenced by any growth in 
VMT or trips. This emissions estimate, the VMT offset ceiling scenario, 
would reflect the maximum attainment emissions that should be allowed 
to occur under the statute as interpreted by the Ninth Circuit because 
it shows what would happen under a scenario in which no offsetting TCSs 
or TCMs have yet been put in place and VMT and trips are held constant 
during the period from the area's base year to its attainment year.
    These two hypothetical status quo estimates are necessary steps in 
identifying target emission levels. Comparison of the first two 
attainment year calculations would identify whether there was a 
hypothetical growth in emissions due to growth in VMT that needs to be 
offset, and as a result whether further TCMs or TCSs beyond those that 
have been adopted and implemented are needed.
    The third calculation incorporates the emissions that are actually 
expected to occur in the area's attainment year after taking into 
account reductions from all enforceable TCSs and TCMs that were put in 
place after the baseline year. This estimate would be based on the VMT 
and trip levels expected to occur in the attainment year (i.e., the VMT 
and trip levels from the first estimate) and all of the TCSs and TCMs 
expected to be in place and for which the SIP will take credit in the 
area's attainment year, including any TCMs and TCSs put in place since 
the base year. This represents the projected actual (attainment year) 
scenario. If this emissions estimate is less than or equal to the 
emissions ceiling that was established in the second of the attainment 
year calculations, the TCSs or TCMs for the attainment year would be 
sufficient to fully offset the hypothetical growth in emissions 
identified by comparison of the first two attainment year calculations.
    If the projected actual attainment year emissions are greater than 
the VMT offset ceiling established in the second of the attainment year 
emissions calculations even after accounting for post-baseline year 
TCSs and TCMs, the state would need to adopt and implement additional 
TCSs or TCMs. To meet the VMT emissions offset requirement of section 
182(d)(1)(A) as interpreted by the Ninth Circuit, the additional TCSs 
or TCMs would need to offset the growth in emissions and bring the 
actual emissions down to at least the same level as the attainment year 
VMT offset ceiling estimate in the second attainment year calculation.
2. The Coachella Valley VMT Offset Demonstration
    The VMT Offset Demonstration uses EMFAC2017 to estimates on-road 
emissions. EMFAC2017 was the latest EPA-approved motor vehicle 
emissions model for California available at the time the VMT Offset 
Demonstration was prepared.\106\ The EMFAC2017 results,

[[Page 26831]]

however, were adjusted based on a sensitivity analysis using older 
previously approved EMFAC models, EMFAC2011 and EMFAC2014. As the VMT 
Offset Demonstration explains, several post-2002 emissions control 
measures are factored into EMFAC2017 and cannot be removed. To correct 
this, the VMT Offset Demonstration included the results of a 
sensitivity analysis to determine the emissions reductions associated 
with CARB's Advanced Clean Cars I program \107\ and the Truck and Bus 
Regulations \108\ with EMFAC2014, and the additional stringency of 
CARB's I/M programs \109\ calculated using EMFAC2011.\110\
---------------------------------------------------------------------------

    \106\ The EPA approved and announced the availability of 
EMFAC2017, the latest update to the EMFAC model for use by State and 
local governments to meet CAA requirements at that time, in a 
rulemaking published at 84 FR 41717 (August 15, 2019).
    \107\ The EPA approved the Advanced Clean Car program in the 
California SIP on June 16, 2016 (81 FR 39424).
    \108\ The EPA approved the Truck and Bus Rule into the 
California SIP on April 4, 2012 (77 FR 20308).
    \109\ The EPA approved California's I/M program into the 
California SIP on July 1, 2010 (75 FR 38023).
    \110\ Two other control programs started after 2002, the Heavy-
Duty Greenhouse Gas Regulation and Low Carbon Fuel Standard, have no 
impact on VOC emissions. VMT Offset Demonstration, p. 9, n. 9.
---------------------------------------------------------------------------

    All of the EMFAC models calculate emissions from two combustion 
processes (i.e., running exhaust and start exhaust) and four 
evaporative processes (i.e., hot soak, running losses, diurnal losses, 
and resting losses). The models combine trip-based VMT data and speed 
distribution from the 2016-2040 RTP/SCS, along with vehicle data from 
the California Department of Motor Vehicles and the corresponding 
emission rates to calculate emissions.
    Emissions from running exhaust, start exhaust, hot soak, and 
running losses are a function of how much a vehicle is driven. As such, 
emissions from these processes are directly related to VMT and vehicle 
trips, and the State included emissions from them in the calculations 
that provide the basis for the revised Coachella Valley VMT Offset 
Demonstration.\111\ Resting and diurnal losses occur independently of 
vehicle activity were and not considered in the demonstration.\112\
---------------------------------------------------------------------------

    \111\ VMT Offset Demonstration, p. 2.
    \112\ This fact is noted in several locations of the VMT Offset 
Demonstration, e.g., p. 10.
---------------------------------------------------------------------------

    The VMT Offset Demonstration also includes the previously described 
three attainment year scenarios (i.e., no new measures; no VMT Growth 
or VMT offset ceiling; and projected actual) for 2023. Table 5 
summarizes the emissions estimates for the base year and the three 
scenarios.

           Table 5--VMT Offset Inventory Scenarios and Results for the 1997 8-Hour Ozone Standards \a\
----------------------------------------------------------------------------------------------------------------
                                                                VMT                  Controls      VOC Emissions
                    Scenario                     ---------------------------------------------------------------
                                                       Year       1000 miles/day       Year             tpd
----------------------------------------------------------------------------------------------------------------
Base Year.......................................            2002          11,091            2002             8.5
No New Measures.................................            2023          14,508            2002             2.8
No New Measures and No VMT Growth (VMT Offset               2002          11,091            2002             2.0
 Ceiling).......................................
Projected Actual................................            2023          14,508            2018             1.9
----------------------------------------------------------------------------------------------------------------
\a\ Source: Coachella Valley VMT Offset Demonstration, Table 1.

    For the base year scenario, CARB ran the EMFAC2017 model for the 
2002 RFP base year using VMT and starts data corresponding to those 
years. For the no new measures scenario, CARB estimated 2023 on-road 
vehicle emissions using EMFAC2017, considering the estimated increase 
in VMT,\113\ but adding 0.33 tpd to account for the additional 
reductions associated with the Advanced Clean Cars I program, Truck and 
Bus Regulation, and I/M programs that are not creditable reductions in 
these calculations. Likewise, CARB added 0.25 tpd to the VMT offset 
ceiling to account for the same factors.
---------------------------------------------------------------------------

    \113\ This estimate included an additional 0.33 tpd based on the 
sensitivity analysis conducted with the EMFAC2011 and EMFAC2014 
models to account for the EMFAC reductions for CARB's Advanced Clean 
Cars I program, Truck and Bus Regulation, and I/M programs.
---------------------------------------------------------------------------

    For the VMT offset ceiling scenario, the State ran the EMFAC2011 
model for the attainment year but with VMT and starts data 
corresponding to base year values. Like the no action scenario, the 
EMFAC2011 model was adjusted to reflect VOC emissions levels in the 
attainment year without the benefits of the on-road motor vehicle 
control programs implemented after the base year. Thus, the VMT offset 
ceiling scenario reflects hypothetical VOC emissions if the State had 
not put in place any TCSs or TCMs after the base year and if there had 
been no growth in VMT or vehicle trips between the base year and the 
attainment year. As shown in Table 5, CARB estimates VMT offset ceiling 
VOC emissions to be 2.0 tpd in 2023.
    The hypothetical growth in emissions due to growth in VMT and trips 
can be determined from the difference between the VOC emissions 
estimates under the no action scenario and the corresponding estimate 
for the VMT offset ceiling scenario. Based on the values in Table 5, 
the hypothetical growth in emissions due to growth in VMT and trips in 
the Coachella Valley would have been 0.8 tpd (i.e., 2.8 tpd minus 2.0 
tpd). This hypothetical difference establishes the level of emissions 
caused by growth in VMT that need to be offset by the combination of 
post-baseline year TCMs and TCSs and any necessary additional TCMs and 
TCSs.
    For the projected actual scenario calculation, the State included 
the emissions benefits from TCSs and TCMs put in place since the base 
year.\114\ In addition to the measures already discussed, a full list 
of CARB mobile source regulations from 1990 through the Plan's 
development appears in Attachment A-1 of the VMT Offset Demonstration. 
While some of these measures were adopted prior to 2002, all or part of 
their implementation occurred after 2002. CARB determined the area 
complied with the VMT Offset Demonstration because actual emissions did 
not exceed the VMT offset ceiling scenario calculation, in accordance 
with EPA guidance.\115\
---------------------------------------------------------------------------

    \114\ As described in Section IV.B.2.c of this document, the 
TCMs are focused in the South Coast Air Basin, which heavily 
influences air quality in the Coachella Valley due to the downwind 
transport.
    \115\ EPA, Office of Transportation and Air Quality, 
``Implementing Clean Air Act Section 182(d)(1)(A): Transportation 
Control Measures and Transportation Control Strategies to Offset 
Growth in Emissions Due to Growth in Vehicle Miles Travelled,'' EPA-
420-B-12-053, August 2012.
---------------------------------------------------------------------------

3. The EPA's Evaluation of the VMT Offset Demonstration
    CARB's VMT Offset Demonstration uses a 2002 RFP base year. This is 
the same year used for the Coachella Valley

[[Page 26832]]

Severe area VMT offset demonstration for the 1997 ozone NAAQS,\116\ it 
corresponds to the Plan's baseline year for the RFP emissions 
inventory, and we find it appropriate for this demonstration.\117\ 
Further, we find CARB's methodology incorporating sensitivity analysis 
to adjust for the periodic change in emissions control measures and the 
omission of resting and diurnal emissions appropriate.
---------------------------------------------------------------------------

    \116\ 81 FR 75764, 75779.
    \117\ The 2002 RFP base year is also consistent with the 
approach described in the 1997 Ozone Implementation Rule--Phase 2. 
See 70 FR 71612, 71632.
---------------------------------------------------------------------------

    As shown in Table 5, the VMT Offset Demonstration projects actual 
2023 attainment-year VOC emissions of 1.9 tpd in the Coachella Valley, 
which is less than the VMT offset ceiling scenario value of 2.0 tpd. 
Therefore, the VMT Offset Demonstration shows that existing measures 
are sufficient to offset the increase due solely to VMT and additional 
trips, consistent with the methodology in the EPA's August 2012 
Guidance, and that no new TCMs or TCSs are required for the area. We 
are proposing to approve the VMT Offset Demonstration.

F. Clean Fuels or Advanced Control Technology for Boilers

1. Statutory and Regulatory Requirements
    Section 182(e)(3) of the CAA provides that SIPs for Extreme 
nonattainment areas require each new, modified, and existing electric 
utility and industrial and commercial boiler that emits more than 25 
tpy of NOX to either burn as its primary fuel natural gas, 
methanol, or ethanol (or a comparably low-polluting fuel), or use 
advanced control technology, such as catalytic control technologies or 
other comparably effective control methods.
    Additional guidance on this requirement is provided in the General 
Preamble.\118\ In the General Preamble, the EPA states that, for the 
purposes of CAA section 182(a)(3), a boiler should generally be 
considered as any combustion equipment used to produce steam and 
generally does not include a process heater that transfers heat from 
combustion gases to process streams.\119\ In addition, boilers with 
rated heat inputs less than 15 million British thermal units (MMBtu) 
per hour that are oil- or gas-fired may generally be considered de 
minimis and exempt from these requirements because it is unlikely that 
they will exceed the 25 tpy NOX emission limit.\120\
---------------------------------------------------------------------------

    \118\ 57 FR 13498, 13523.
    \119\ 57 FR 13498, 13523.
    \120\ Id at 13524.
---------------------------------------------------------------------------

2. Summary of the State's Submission
    The Coachella Valley Ozone Plan discusses compliance with the 
requirements of CAA section 182(e)(3) by reference to SCAQMD Rules 1146 
(``Emissions of Oxides of Nitrogen from Industrial, Institutional, and 
Commercial Boilers, Steam Generators, and Process Heaters'') and 1135 
(``Emissions of Oxides of Nitrogen from Electricity Generating 
Facilities'').\121\ These rules require the best available retrofit 
control technology (BARCT) for existing boilers. New or modified 
sources with emissions increases are subject to California best 
available control technology (BACT) requirements, which are comparable 
to the federal lowest achievable emissions rate (LAER) requirements for 
major sources as defined in CAA section 171(3). Accordingly, the Plan 
concludes that no additional action is needed to satisfy the CAA 
section 182(e)(3) requirement for the Coachella Valley's 
reclassification to Extreme.
---------------------------------------------------------------------------

    \121\ Coachella Valley Ozone Plan, p. 6-31.
---------------------------------------------------------------------------

3. The EPA's Review of the State's Submission
    In our previous evaluation of the 2016 AQMP, which includes a 
similar documentation of compliance with CAA 182(e)(3), we determined 
that SCAQMD Rules 1303, 1146, and 2004 satisfy the clean fuel or 
advanced control technology for boilers requirement in CAA section 
182(e)(3) for the South Coast Air Basin.\122\ For similar reasons, we 
find that the requirements for new, modified, and existing boilers in 
approved SCAQMD Rules 1303, 1146, and 2004 satisfy the clean fuel or 
advanced control technology for boilers requirement in CAA section 
182(e)(3), and based on this finding, we propose to find the State has 
demonstrated that these requirements are met for the Coachella Valley 
for the 1997 ozone NAAQS.
---------------------------------------------------------------------------

    \122\ 84 FR 28132, 28164.
---------------------------------------------------------------------------

G. Other CAA Requirements

1. Contingency Measures
    Under the CAA, ozone nonattainment areas classified under subpart 2 
as Serious or above must include in their SIPs contingency measures 
consistent with sections 172(c)(9) and 182(c)(9). CAA section 172(c)(9) 
requires states with nonattainment areas to provide for the 
implementation of specific measures to be undertaken if the area fails 
to make RFP or to attain the NAAQS by the applicable attainment date. 
Such measures must be included in the SIP as contingency measures to 
take effect in any such case without further action by the state or the 
EPA. CAA section 182(c)(9) requires states to provide contingency 
measures in the event that an ozone nonattainment area fails to meet 
any applicable RFP milestone. Contingency measures are additional 
controls or measures to be implemented in the event an area fails to 
make RFP or to attain the NAAQS by the attainment date.
    In March 2023, the EPA announced a new draft guidance addressing 
the contingency measures requirement of section 172(c)(9), entitled 
``DRAFT: Guidance on the Preparation of State Implementation Plan 
Provisions that Address the Nonattainment Area Contingency Measure 
Requirements for Ozone and Particulate Matter,'' and provided an 
opportunity for public comment.\123\ The principal differences between 
this draft revised guidance and previous existing guidance on 
contingency measures relate to the EPA's recommendations concerning the 
specific amount of emissions reductions that implementation of 
contingency measures should achieve, and the timing for when the 
emissions reductions from the contingency measures should occur.
---------------------------------------------------------------------------

    \123\ 88 FR 17571 (March 23, 2023).
---------------------------------------------------------------------------

    The Plan explains that the District intends to amend SCAQMD Rule 
445, ``Wood Burning Devices,'' to include potential contingency 
provisions for Coachella Valley for the 1997 8-hour ozone 
standards.\124\ To date, the EPA has not received a submittal to 
address the 1997 ozone contingency measures requirements of CAA 
sections 172(c)(9) and 182(c)(9) for the Coachella Valley. The EPA is 
not proposing action on the Coachella Valley contingency measures 
requirement for the 1997 ozone NAAQS in this rulemaking.
---------------------------------------------------------------------------

    \124\ Coachella Valley Ozone Plan p. 6-30.
---------------------------------------------------------------------------

2. CAA Section 185 Fees
    Under sections 182(d)(3), (e), and (f) and 185 of the Act, states 
with ozone nonattainment areas classified as Severe or Extreme are 
required to submit a revision to the SIP that would require major 
stationary sources of VOC or NOX to pay a fee upon a failure 
to attain by the applicable attainment date. Under CAA section 185, 
this fee is calculated as $5,000 in 1990 dollars, adjusted for 
inflation, for every ton emitted by the source during the calendar year 
in excess of 80 percent of the source's

[[Page 26833]]

actual emissions in the applicable attainment year.\125\
---------------------------------------------------------------------------

    \125\ CAA section 185(a) and (b).
---------------------------------------------------------------------------

    While the EPA has approved SCAQMD Rule 317 into the SIP for the 1-
hour ozone standards, the SCAQMD has not submitted a rule to address 
the requirement of CAA section 185 for the 1997 8-hour ozone standards. 
We are aware, however, that the SCAQMD is working to create to a rule 
to address this requirement, SCAQMD Rule 317.1, ``Clean Air Act 
Nonattainment Fees for the 8-Hour Ozone Standards.'' The SCAQMD has 
prepared a draft rule and held a workshop to discuss it on November 7, 
2023.\126\ The EPA is not proposing action on the CAA Section 185 fee 
requirement for the 1997 ozone NAAQS in this rulemaking.
---------------------------------------------------------------------------

    \126\ https://www.aqmd.gov/home/rules-compliance/rules/scaqmd-rule-book/proposed-rules/rule-317-and-317-1.
---------------------------------------------------------------------------

3. New Source Review Rules
    Section 182(a)(2)(C) of the CAA requires states to develop SIP 
revisions containing permit programs for each ozone nonattainment area. 
These SIP revisions must include requirements for permits in accordance 
with CAA sections 172(c)(5) and 173 for the construction and operation 
of each new or modified major stationary source for VOC and 
NOX anywhere in the nonattainment area.\127\ In addition, 
CAA section 182(e)(1) requires the permitting offset ratios for 
volatile organic compound and NOX for major sources and 
modifications in an Extreme nonattainment area to be at least 1.5 to 1, 
or at least 1.2 to 1 if the plan requires all existing major sources in 
the nonattainment area to use the best available control technology. 
SCAQMD Rule 1302, ``Definitions,'' and Rule 2000, ``General'' (part of 
the RECLAIM regulations), have been submitted to address these 
requirements.\128\ The EPA has not yet acted on this submittal.
---------------------------------------------------------------------------

    \127\ See also CAA section 182(e).
    \128\ Letter dated February 12, 2021, from Richard W. Corey, 
CARB, to Deborah Jordan, EPA Region IX (submitted electronically on 
February 12, 2021).
---------------------------------------------------------------------------

4. Clean Fuels for Fleets
    Section 182(c)(4)(A) of the CAA requires states to submit SIP 
revisions to implement the clean-fuel vehicle program for fleets 
described at CAA section 246 (``Clean Fuels Fleet Program'') in each 
ozone nonattainment area classified as Serious and above. Section 
182(c)(4)(B) of the CAA allows states to opt out of the federal Clean 
Fuels Fleet Program by submitting a SIP revision consisting of a 
program or programs that will result in at least equivalent long-term 
reductions in ozone precursors and toxic air emissions.
    In 1994, CARB submitted a SIP revision to the EPA to opt out of the 
Clean Fuels Fleet Program. The submittal included a demonstration that 
California's low-emissions vehicle program achieved emissions 
reductions at least as large as would be achieved by the federal 
program. The EPA approved the SIP revision to opt-out of the federal 
program on August 27, 1999.\129\
---------------------------------------------------------------------------

    \129\ 64 FR 46849 (August 27, 1999).
---------------------------------------------------------------------------

    Recent EPA guidance for the 2008 and 2015 ozone standards \130\ 
identifies several methods to demonstrate compliance with the Clean 
Fuels Fleet Program requirement. Among them, a state may submit a 
certification SIP revision if it has ``an approved [Clean Fuels Fleet 
Program] or substitute measure(s) that it is continuing to implement, 
and the state does not plan to make any changes to the program or 
substitute measure(s).'' \131\ Consistent with this guidance, the EPA 
approved the ``California Clean Fuels for Fleets Certification for the 
70 ppb (2015) Ozone Standard,'' which included Coachella Valley, in a 
final rule dated May 25, 2023.\132\ However, because the Plan does not 
contain a certification for the 1997 ozone standards, the EPA is taking 
no action regarding this requirement as part of this action.
---------------------------------------------------------------------------

    \130\ EPA, Office of Transportation and Air Quality, ``Guidance 
for Fulfilling the Clean Fuel Fleets Requirement of the Clean Air 
Act,'' EPA-420-B-22-027, June 2022.
    \131\ Id. at 8.
    \132\ 88 FR 33830.
---------------------------------------------------------------------------

5. Enhanced Monitoring
    Section 182(c)(1) of the CAA requires that all ozone nonattainment 
areas classified as Serious or above implement measures to enhance and 
improve monitoring for ambient concentrations of ozone, NOX, 
and VOC, and to improve monitoring of emissions of NOX and 
VOC. The enhanced monitoring network for ozone is referred to as the 
photochemical assessment monitoring station (PAMS) network. The EPA 
promulgated final PAMS regulations on February 12, 1993.\133\
---------------------------------------------------------------------------

    \133\ 58 FR 8452 (February 12, 1993).
---------------------------------------------------------------------------

    On November 10, 1993, CARB submitted to the EPA a SIP revision 
addressing the PAMS network for six ozone nonattainment areas in 
California, including the Southeast Desert, to meet the enhanced 
monitoring requirements of CAA section 182(c)(1) and the PAMS 
regulations.\134\ The EPA determined that the PAMS SIP revision met all 
applicable requirements for enhanced monitoring and approved the PAMS 
submittal into the California SIP.\135\
---------------------------------------------------------------------------

    \134\ In the designation of the 1997 ozone NAAQS nonattainment 
areas, the Southeast Desert was split into the Los Angeles and San 
Bernardino (Western Mojave Desert) and Coachella Valley 
Nonattainment Areas.
    \135\ 82 FR 45191 (September 28, 2017).
---------------------------------------------------------------------------

    Appendix B, ``Enhanced Ozone Monitoring Plan,'' of the District's 
Five-Year Monitoring Network Assessment, dated June 1, 2020, describes 
the District's plan to address the requirements of section 
182(c)(1).\136\ The EPA has approved the District's review, including 
the Enhanced Ozone Monitoring Plan in a letter dated October 28, 
2020.\137\
---------------------------------------------------------------------------

    \136\ Letter dated June 26, 2020, from Rene Bermudez, SCAQMD, to 
Jennifer Williams, EPA Region IX, transmitting the District's Five-
Year Monitoring Network Assessment.
    \137\ Letter dated October 28, 2020, from Gwen Yoshimura, EPA 
Region IX, to Matt Miyasato, SCAQMD.
---------------------------------------------------------------------------

    Prior to 2006, the EPA's ambient air monitoring regulations in 40 
CFR part 58 (``Ambient Air Quality Surveillance'') set forth specific 
SIP requirements (see former 40 CFR 52.20). In 2006, the EPA 
significantly revised and reorganized 40 CFR part 58.\138\ Under 
revised 40 CFR part 58, SIP revisions are no longer required; rather, 
compliance with EPA monitoring regulations is established through 
review of required annual monitoring network plans.\139\ Therefore, 
based on our review and approval of the 2020 Five-Year Network 
Monitoring Assessment we find the District has adequately addressed the 
enhanced monitoring requirements under CAA section 182(c)(1) for the 
Coachella Valley.
---------------------------------------------------------------------------

    \138\ 71 FR 61236 (October 17, 2006).
    \139\ 40 CFR 58.2(b) now provides ``The requirements pertaining 
to provisions for an air quality surveillance system in the SIP are 
contained in this part.''
---------------------------------------------------------------------------

6. Enhanced Vehicle Inspection and Maintenance Programs
    Section 182(c)(3) of the CAA requires states with ozone 
nonattainment areas classified as Serious or above to implement an 
enhanced motor vehicle inspection and maintenance program in those 
areas. The requirements for those programs are provided in CAA section 
182(c)(3) and 40 CFR part 51, subpart S. The EPA approved the State of 
California's SIP revision addressing this requirement in a final rule 
dated July 1, 2010.\140\
---------------------------------------------------------------------------

    \140\ 75 FR 38023.
---------------------------------------------------------------------------

V. Environmental Justice Considerations

    We expect that this proposed action, if approved, will generally be 
neutral or contribute to a reduction in adverse environmental and 
health impacts on all

[[Page 26834]]

populations in the Coachella Valley, including people of color and low-
income populations in the area. At a minimum, the approved action would 
not worsen any existing air quality and is expected to ensure the area 
is meeting requirements to attain 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. In responding to 
public concerns about environmental justice in eastern Coachella 
Valley, the Plan notes that (1) Assembly Bill 617 funding has reduced 
pollutant emissions in Eastern Coachella Valley by 63.1 tpy of 
NOX, 7.5 tpy of VOC, and 5.3 tpy of diesel particulate 
matter,\141\ and (2) the SCAQMD has provided $966,667 in energy 
efficiency upgrades, reducing energy costs for homes within designated 
environmental justice areas of Indio and Eastern Coachella Valley.\142\ 
The 2016 AQMP also identifies an Environmental Justice Advisory Group 
established to ``advise and assist SCAQMD in protecting and improving 
public health in SCAQMD's most impacted communities through the 
reduction and prevention of air pollution.'' \143\
---------------------------------------------------------------------------

    \141\ Coachella Valley Ozone Plan, p. 9-8. SCAQMD's website 
identifies Assembly Bill 617 Community Air Initiatives as 
``community based efforts that focus on improving air quality and 
public health in environmental justice communities.'' See http://www.aqmd.gov/nav/about/initiatives/environmental-justice/ab617-134.
    \142\ Id.
    \143\ 2016 AQMP p. 9-7.
---------------------------------------------------------------------------

VI. The EPA's Proposed Action and Public Comment

    For the reasons discussed in this document, the EPA is proposing to 
approve the California's SIP submittal for the Coachella Valley 
addressing the Extreme nonattainment areas for the 1997 ozone NAAQS. 
The EPA is proposing to approve the following elements of SCAQMD's 
``Final Coachella Valley Extreme Area Plan for 1997 8 Hour Ozone 
Standard,'' dated December 2020, under CAA section 110(k)(3):
    1. The RACM demonstration as meeting the requirements of CAA 
section 172(c)(1) and 40 CFR 51.1105(a)(1) and 51.1100(o)(17);
    2. The ROP and RFP demonstrations as meeting the requirements of 
CAA sections 172(c)(2) and 182(c)(2)(B) and 40 CFR 51.1105(a)(1) and 
51.1100(o)(4); and
    3. The attainment demonstration as meeting the requirements of CAA 
section 182(c)(2)(A) and 40 CFR 51.1105(a)(1) and 51.1100(o)(12).
    The EPA is also proposing to approve CARB's ``2020 Coachella Valley 
Vehicle Miles Traveled Emissions Offset Demonstration,'' release date 
January 22, 2022. The demonstration provides for transportation control 
strategies and measures sufficient to offset any growth in emissions 
from growth in VMT or the number of vehicle trips, and to provide for 
RFP and attainment, as meeting the requirements of CAA section 
182(d)(1)(A) and 40 CFR 51.1105(a)(1) and 51.1100(o)(10). Additionally, 
we are proposing to find that the State has satisfied the clean fuel or 
advanced control technology for boilers requirement in CAA section 
182(e)(3) for the Coachella Valley for the 1997 ozone NAAQS. The EPA is 
soliciting public comments on the issues discussed in this document. We 
will accept comments from the public on this action for the next 30 
days. We will consider these comments before taking final action.

VII. 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), 13563 (76 FR 3821, January 21, 2011) and 
14094 (88 FR 21879, April 11, 2023);
     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 subject to Executive Order 13045 (62 FR 19885, 
April 23, 1997) because it proposes to approve a state program;
     Is not a significant regulatory action subject to 
Executive Order 13211 (66 FR 28355, May 22, 2001); and
     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.
    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 proposed action 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).
    Furthermore, Executive Order 12898, ``Federal Actions To Address 
Environmental Justice in Minority Populations and Low-Income 
Populations'' (59 FR 7629, February 16, 1994), directs Federal agencies 
to identify and address ``disproportionately high and adverse human 
health or environmental effects'' of their actions on minority 
populations and low-income populations to the greatest extent 
practicable and permitted by law. The EPA defines environmental justice 
(EJ) as ``the fair treatment and meaningful involvement of all people 
regardless of race, color, national origin, or income with respect to 
the development, implementation, and enforcement of environmental laws, 
regulations, and policies.'' The EPA further defines the term fair 
treatment to mean that ``no group of people should bear a 
disproportionate burden of environmental harms and risks, including 
those resulting from the negative environmental consequences of 
industrial, governmental, and commercial operations or programs and 
policies.''
    The State did not evaluate environmental justice considerations as 
part of its SIP submittal; the CAA and applicable implementing 
regulations neither prohibit nor require such an evaluation. However, 
as described in Section IV of this document, the District has taken 
measures to address environmental justice concerns within the Coachella 
Valley. The EPA did not perform an EJ analysis and did not consider EJ 
in this action. Due to the nature of this proposed action, if 
finalized, this action is expected to have

[[Page 26835]]

a neutral to positive impact on the air quality of Coachella Valley. 
Consideration of EJ is not required as part of this action, and there 
is no information in the record inconsistent with the stated goal of 
Executive Order 12898, to achieve environmental justice for people of 
color, low-income populations, and Indigenous peoples.

List of Subjects in 40 CFR Part 52

    Environmental protection, Air pollution control, Incorporation by 
reference, Intergovernmental regulations, Nitrogen dioxide, Ozone, 
Reporting and recordkeeping requirements, Volatile organic compounds.

    Dated: April 9, 2024.
Martha Guzman Aceves,
Regional Administrator, Region IX.
[FR Doc. 2024-08121 Filed 4-15-24; 8:45 am]
BILLING CODE 6560-50-P