[Federal Register Volume 88, Number 134 (Friday, July 14, 2023)]
[Proposed Rules]
[Pages 45276-45323]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-14687]



[[Page 45275]]

Vol. 88

Friday,

No. 134

July 14, 2023

Part II





Environmental Protection Agency





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40 CFR Part 52





Air Quality State Implementation Plans; Approvals and Promulgations: 
California; 1997 Annual Fine Particulate Matter Serious and Clean Air 
Act Section 189(d) Nonattainment Area Requirements; San Joaquin Valley, 
CA; Proposed Rule

  Federal Register / Vol. 88, No. 134 / Friday, July 14, 2023 / 
Proposed Rules  

[[Page 45276]]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R09-OAR-2023-0263; FRL-10941-01-R9]


Air Quality State Implementation Plans; Approvals and 
Promulgations: California; 1997 Annual Fine Particulate Matter Serious 
and Clean Air Act Section 189(d) Nonattainment Area Requirements; San 
Joaquin Valley, CA

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) is proposing to 
approve portions of state implementation plan (SIP) revisions submitted 
by the State of California to meet Clean Air Act (CAA or ``Act'') 
requirements for the 1997 annual fine particulate matter 
(PM2.5) national ambient air quality standards (NAAQS or 
``standards'') in the San Joaquin Valley PM2.5 nonattainment 
area. Specifically, the EPA is proposing to approve those portions of 
the submitted SIP revisions as they pertain to the Serious 
nonattainment area and CAA section 189(d) requirements for the 1997 
annual PM2.5 NAAQS, except for the requirement for 
contingency measures. In addition, the EPA is proposing to approve 2020 
and 2023 motor vehicle emissions budgets and the trading mechanism for 
use in transportation conformity analyses for the 1997 annual 
PM2.5 NAAQS. The EPA will accept comments on this proposed 
rule during a 30-day public comment period.

DATES: Any comments on this proposal must be received by August 14, 
2023.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R09-
OAR-2023-0263 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 (e.g., 
audio or video) 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: Ashley Graham, Geographic Strategies 
and Modeling Section (AIR-2-2), EPA Region IX, 75 Hawthorne Street, San 
Francisco, CA 94105, (415) 972-3877, or by email at 
[email protected].

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

Table of Contents

I. Background for Proposed Action
    A. PM2.5 NAAQS
    B. San Joaquin Valley PM2.5 Designations, 
Classifications, and SIP Revisions
II. Summary and Completeness Review of the San Joaquin Valley 
PM2.5 Plan
    A. 2018 PM2.5 Plan and 15 [micro]g/m\3\ SIP Revision
    B. Procedural Requirements for SIPs and SIP Revisions
III. Clean Air Act Requirements for PM2.5 Serious Area 
Plans and for Serious PM2.5 Areas That Fail To Attain
    A. Requirements for PM2.5 Serious Area Plans
    B. Requirements for Serious PM2.5 Areas That Fail To 
Attain
IV. Review of the San Joaquin Valley PM2.5 Plan for the 
1997 Annual PM2.5 NAAQS
    A. Emissions Inventories
    B. PM2.5 Precursors
    C. Attainment Plan Control Strategy
    D. Attainment Demonstration and Modeling
    E. Reasonable Further Progress and Quantitative Milestones
    F. Motor Vehicle Emission Budgets
    G. Nonattainment New Source Review Requirements Under CAA 
Section 189(e)
V. Environmental Justice Considerations
VI. CAA Section 110(a)(2)(E)(i) ``Necessary Assurances'' and Title 
VI of the Civil Rights Act of 1964
VII. Summary of Proposed Action and Request for Public Comment
VIII. Statutory and Executive Order Reviews

I. Background for Proposed Action

A. PM2.5 NAAQS

    Under section 109 of the CAA, the EPA has established NAAQS for 
certain pervasive air pollutants (referred to as ``criteria 
pollutants'') and conducts periodic reviews of the NAAQS to determine 
whether the EPA should revise or establish new NAAQS to protect public 
health.
    On July 18, 1997, the EPA revised the NAAQS for particulate matter 
by establishing new NAAQS for particles with an aerodynamic diameter 
less than or equal to a nominal 2.5 micrometers (PM2.5).\1\ 
The EPA established primary and secondary annual and 24-hour standards 
for PM2.5.\2\ The EPA set the annual primary and secondary 
standards at 15.0 micrograms per cubic meter ([mu]g/m\3\) based on a 
three-year average of annual mean PM2.5 concentrations, and 
set the 24-hour primary and secondary standards at 65 [mu]g/m\3\ based 
on the three-year average of the 98th percentile of 24-hour 
PM2.5 concentrations at each monitoring site within an 
area.\3\ Collectively, we refer herein to the 1997 annual and 24-hour 
PM2.5 NAAQS as the ``1997 PM2.5 NAAQS'' or ``1997 
PM2.5 standards.''
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    \1\ 62 FR 38652.
    \2\ For a given air pollutant, ``primary'' NAAQS are those 
determined by the EPA as requisite to protect the public health, 
allowing an adequate margin of safety, and ``secondary'' standards 
are those determined by the EPA as requisite to protect the public 
welfare from any known or anticipated adverse effects associated 
with the presence of such air pollutant in the ambient air. See CAA 
section 109(b).
    \3\ 40 CFR 50.7.
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    On October 17, 2006, the EPA revised the level of the 24-hour 
PM2.5 NAAQS to 35 [mu]g/m\3\,\4\ and on January 15, 2013, 
the EPA revised the level of the primary annual PM2.5 NAAQS 
to 12.0 [mu]g/m\3\.\5\ Even though the EPA lowered the 24-hour and 
annual PM2.5 NAAQS, the 1997 24-hour PM2.5 NAAQS 
remain in effect and the 1997 primary annual PM2.5 NAAQS 
remains in effect in areas designated nonattainment for that NAAQS.\6\
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    \4\ 71 FR 61144.
    \5\ 78 FR 3086.
    \6\ 40 CFR 50.13(d).
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    The EPA established each of the PM2.5 NAAQS after 
considering substantial evidence from numerous health studies 
demonstrating that serious health effects are associated with exposures 
to PM2.5 concentrations above these levels. Epidemiological 
studies have shown statistically significant correlations between 
elevated PM2.5 levels and premature mortality. Other 
important health effects associated with PM2.5 exposure 
include aggravation of respiratory and cardiovascular disease (as 
indicated by increased hospital admissions, emergency room visits, 
absences from school or work, and restricted activity dates), changes 
in lung function and increased respiratory

[[Page 45277]]

symptoms, and new evidence for more subtle indicators of cardiovascular 
health. Individuals particularly sensitive to PM2.5 exposure 
include older adults, people with heart and lung disease, and 
children.\7\
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    \7\ EPA, Air Quality Criteria for Particulate Matter, No. EPA/
600/P-99/002aF and EPA/600/P-99/002bF, October 2004.
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    PM2.5 can be particles emitted by sources directly into 
the atmosphere as a solid or liquid particle (``primary 
PM2.5'' or ``direct PM2.5''), or can be particles 
that form in the atmosphere as a result of various chemical reactions 
from PM2.5 precursor emissions emitted by sources 
(``secondary PM2.5''). The EPA has identified the precursors 
of PM2.5 to be oxides of nitrogen (``NOX''), 
sulfur oxides (``SOX''), volatile organic compounds 
(``VOC''), and ammonia.\8\
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    \8\ For example, see 72 FR 20586, 20589 (April 25, 2007).
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B. San Joaquin Valley PM2.5 Designations, Classifications, 
and SIP Revisions

    Following promulgation of a new or revised NAAQS, the EPA is 
required under CAA section 107(d) to designate areas throughout the 
nation as attainment, nonattainment, or unclassifiable for the NAAQS. 
Effective April 5, 2005, the EPA established the initial air quality 
designations for the 1997 annual and 24-hour PM2.5 NAAQS, 
using air quality monitoring data for the three-year periods of 2001-
2003 and 2002-2004.\9\ The EPA designated the San Joaquin Valley as 
nonattainment for both the 1997 annual PM2.5 NAAQS (15.0 
[micro]g/m\3\) and the 1997 24-hour PM2.5 NAAQS (65 
[micro]g/m\3\).\10\
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    \9\ 70 FR 944 (January 5, 2005).
    \10\ 40 CFR 81.305.
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    The San Joaquin Valley PM2.5 nonattainment area 
encompasses over 23,000 square miles and includes all or part of eight 
counties: San Joaquin, Stanislaus, Merced, Madera, Fresno, Tulare, 
Kings, and the valley portion of Kern.\11\ The area is home to four 
million people and is one of the nation's leading agricultural regions. 
Stretching over 250 miles from north to south and averaging 80 miles 
wide, it is partially enclosed by the Coast Mountain range to the west, 
the Tehachapi Mountains to the south, and the Sierra Nevada range to 
the east. Under State law, the San Joaquin Valley Unified Air Pollution 
Control District (SJVUAPCD or ``District'') has primary responsibility 
for developing plans to provide for attainment of the NAAQS in this 
area. The District works cooperatively with the California Air 
Resources Board (CARB) in preparing attainment plans. Authority for 
regulating sources under State jurisdiction in the San Joaquin Valley 
is split under State law between the District, which has responsibility 
for regulating stationary and most area sources, and CARB, which has 
responsibility for regulating most mobile sources.
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    \11\ For a precise description of the geographic boundaries of 
the San Joaquin Valley nonattainment area, see 40 CFR 81.305.
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    At the time of the initial designations for the 1997 
PM2.5 NAAQS, the EPA interpreted the CAA to require 
implementation of the NAAQS under the general nonattainment plan 
requirements of subpart 1.\12\ Under subpart 1, states were required to 
submit nonattainment plan SIP submissions within three years of the 
effective date of designations, that, among other things, provided for 
implementation of reasonably available control measures (RACM), 
reasonable further progress (RFP), contingency measures, and a modeled 
attainment demonstration showing attainment of the NAAQS as 
expeditiously as practicable but no later than five years from the 
designation (in this instance, no later than April 5, 2010) unless the 
state justified an attainment date extension of up to five years.\13\
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    \12\ 72 FR 20586.
    \13\ CAA sections 172(a)(2), 172(c)(1), 172(c)(2), and 
172(c)(9).
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    Between 2007 and 2011, California submitted six nonattainment plan 
and supporting SIP revisions to address nonattainment area planning 
requirements for the 1997 PM2.5 NAAQS in the San Joaquin 
Valley,\14\ which we refer to collectively as the ``2008 
PM2.5 Plan.'' On November 9, 2011, the EPA approved the 
portions of the 2008 PM2.5 Plan, as revised in 2009 and 
2011, that addressed attainment of the 1997 PM2.5 NAAQS in 
the San Joaquin Valley nonattainment area, except for the attainment 
contingency measures, which we disapproved.\15\ We also granted the 
State's request to extend the attainment deadline for the 1997 
PM2.5 NAAQS in the San Joaquin Valley to April 5, 2015.\16\
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    \14\ 76 FR 69896, n. 2 (November 9, 2011).
    \15\ Id. at 69924.
    \16\ Id.
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    Following a January 4, 2013 decision of the U.S. Court of Appeals 
for the D.C. Circuit remanding the EPA's 2007 implementation rule for 
the 1997 PM2.5 NAAQS,\17\ the EPA published a final rule on 
June 2, 2014, classifying the San Joaquin Valley as a ``Moderate'' 
nonattainment area for the 1997 PM2.5 NAAQS under subpart 4, 
part D of title I of the Act.\18\ In that action, the EPA acknowledged 
that states must meet both subpart 1 and subpart 4 requirements in 
nonattainment plan SIP submissions for the 1997 24-hour and annual 
PM2.5 NAAQS and provided states with additional time to 
supplement or withdraw and resubmit any pending nonattainment plan SIP 
submissions.
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    \17\ Natural Resources Defense Council v. EPA, 706 F.3d. 428 
(D.C. Cir. 2013) (``NRDC''). In NRDC, the court held that the EPA 
erred in implementing the 1997 PM2.5 standards solely 
pursuant to the general implementation requirements of subpart 1, 
without also considering the requirements specific to nonattainment 
areas for particles less than or equal to 10 [micro]m in diameter 
(PM10) in subpart 4, part D of title I of the CAA. The 
court reasoned that the plain meaning of the CAA requires 
implementation of the 1997 PM2.5 standards under subpart 
4 because PM2.5 falls within the statutory definition of 
PM10 and is thus subject to the same statutory 
requirements as PM10. The court remanded the rule, 
without vacatur, and instructed the EPA ``to repromulgate these 
rules pursuant to Subpart 4 consistent with this opinion.''
    \18\ 79 FR 31566.
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    Effective May 7, 2015, the EPA reclassified the San Joaquin Valley 
as a ``Serious'' nonattainment area for the 1997 PM2.5 NAAQS 
based on our determination that the State could not practicably attain 
these NAAQS in the San Joaquin Valley nonattainment area by the latest 
statutory Moderate area attainment date, i.e., April 5, 2015.\19\ Upon 
reclassification as a Serious area, the State became subject to the 
requirement of CAA section 188(c)(2) to attain the 1997 
PM2.5 NAAQS as expeditiously as practicable but no later 
than ten years after designation, i.e., by no later than December 31, 
2015. California submitted its Serious area plan for the 1997 
PM2.5 NAAQS for the San Joaquin Valley in two submissions 
dated June 25, 2015, and August 13, 2015, including a request under 
section 188(e) to extend the attainment date for the 1997 24-hour 
PM2.5 NAAQS by three years (to December 31, 2018) and to 
extend the attainment date for the 1997 annual PM2.5 NAAQS 
by five years (to December 31, 2020). On February 9, 2016, the EPA 
proposed to approve most of the Serious area plan and to grant the 
State's request for extensions of the December 31, 2015 attainment 
date.\20\ However, on October 6, 2016, after considering public 
comments, the EPA denied California's request for these extensions of 
the attainment dates.\21\ Consequently, on November 23, 2016, the EPA 
determined that the San Joaquin Valley had failed to attain the 1997 
24-hour and annual PM2.5 NAAQS

[[Page 45278]]

by the December 31, 2015 Serious area attainment date.\22\ This 
determination triggered a requirement for California to submit a new 
SIP submission for the 1997 24-hour and annual PM2.5 NAAQS 
for the San Joaquin Valley that satisfies the requirements of CAA 
section 189(d). The statutory deadline for this additional SIP 
submission was December 31, 2016. The EPA did not finalize the actions 
proposed on February 9, 2016, with respect to the submitted Serious 
area plan.\23\
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    \19\ 80 FR 18528 (April 7, 2015).
    \20\ 81 FR 6936. California's request for extension of the 
Serious Area attainment date for the San Joaquin Valley accompanied 
its Serious Area attainment plan for the 1997 PM2.5 NAAQS 
and related motor vehicle emission budgets, submitted June 25, 2015 
and August 13, 2015, respectively.
    \21\ 81 FR 69396.
    \22\ 81 FR 84481.
    \23\ 81 FR 69396, 69400.
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    On December 6, 2018, the EPA determined that California had failed 
to submit a complete section 189(d) attainment plan for the 1997 24-
hour and annual PM2.5 NAAQS, among other required SIP 
submissions for the San Joaquin Valley, by the statutory deadlines.\24\ 
This finding, which became effective on January 7, 2019, triggered 
clocks under CAA section 179(a) for the application of emissions offset 
sanctions 18 months after the finding, and highway funding sanctions 6 
months thereafter, unless the EPA affirmatively determined that the 
State made a complete SIP submission addressing the identified failure 
to submit deficiencies.\25\ The finding also triggered the obligation 
under CAA section 110(c) for the EPA to promulgate a federal 
implementation plan no later than two years after the finding, unless 
the State has submitted, and the EPA has approved, the required SIP 
submission.\26\
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    \24\ 83 FR 62720.
    \25\ Id. at 62723.
    \26\ Id.
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    On May 10, 2019, CARB submitted the ``2018 Plan for the 1997, 2006, 
and 2012 PM2.5 Standards,'' adopted by the SJVUAPCD on 
November 15, 2018, and by CARB on January 24, 2019 (``2018 
PM2.5 Plan'').\27\ The 2018 PM2.5 Plan addresses 
the Serious area nonattainment plan and CAA section 189(d) requirements 
for the 1997 24-hour and annual PM2.5 NAAQS, among other 
requirements for the 2006 and 2012 PM2.5 NAAQS.\28\ The 2018 
PM2.5 Plan incorporates by reference the ``San Joaquin 
Valley Supplement to the 2016 State Strategy for the State 
Implementation Plan'' (``Valley State SIP Strategy''), a related plan 
adopted by CARB on October 25, 2018, and submitted to the EPA with the 
2018 PM2.5 Plan on May 10, 2019.\29\ CARB clarified in its 
submittal letter that the 2018 PM2.5 Plan superseded past 
submissions to the EPA that the agency had not yet acted on for the 
1997 PM2.5 NAAQS, including the 2015 Serious area attainment 
plan submissions.\30\ On June 24, 2020, the EPA issued a letter finding 
these submissions complete and terminating the sanctions clocks under 
CAA section 179(a).\31\
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    \27\ Letter dated May 9, 2019, from Richard Corey, Executive 
Officer, CARB, to Mike Stoker, Regional Administrator, EPA Region 9.
    \28\ The EPA previously acted on those portions of the 2018 
PM2.5 Plan that pertain to the 2006 24-hour 
PM2.5 NAAQS (except for contingency measures) (85 FR 
44192, July 22, 2020), and Moderate area planning requirements for 
the 2012 annual PM2.5 NAAQS and 2006 24-hour 
PM2.5 NAAQS contingency measures (86 FR 67343, November 
26, 2021). On December 29, 2021, the EPA proposed action on those 
portions of the plan that pertain to the Serious area requirements 
for the 2012 annual PM2.5 NAAQS (86 FR 74310). On October 
5, 2022, the EPA issued a supplemental proposal with respect to the 
Serious area requirements for the 2012 PM2.5 NAAQS (87 FR 
60494), and on October 27, 2022, California withdrew those portions 
of the plan that pertained to those requirements (letter dated 
October 27, 2022, from Steven S. Cliff, Executive Officer, CARB, to 
Martha Guzman, Regional Administrator, EPA Region IX).
    \29\ Id.
    \30\ The 2015 Serious area attainment plan submissions include 
the ``2015 Plan for the 1997 Standard'' (submitted by CARB on June 
25, 2015) and motor vehicle emission budgets (submitted by CARB 
August 13, 2015)
    \31\ Letter dated June 24, 2020, from Elizabeth J. Adams, 
Director, Air and Radiation Division, EPA Region IX, to Richard 
Corey, Executive Officer, CARB, Subject: ``RE: Completeness Finding 
for State Implementation Plan (SIP) Submissions for San Joaquin 
Valley for the 1997, 2006, and 2012 Fine Particulate Matter 
(PM2.5) National Ambient Air Quality Standards (NAAQS) 
and Termination of Clean Air Act (CAA) Sanction Clocks.''
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    On January 28, 2022, the EPA approved those portions of the 2018 
PM2.5 Plan that pertain to the 1997 24-hour PM2.5 
NAAQS, except for the contingency measure element, which the EPA 
disapproved.\32\ As part of that action, the EPA also finalized a 
determination that the San Joaquin Valley attained the 1997 24-hour 
PM2.5 NAAQS by the applicable attainment date of December 
31, 2020 and that therefore the requirement for contingency measures no 
longer applies in the San Joaquin Valley nonattainment area for the 
1997 24-hour PM2.5 NAAQS.\33\ Because the EPA found that the 
State has satisfied its planning obligations for the San Joaquin Valley 
with respect to the 1997 24-hour PM2.5 NAAQS, this proposed 
action addresses only the requirements for the 1997 annual 
PM2.5 NAAQS.
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    \32\ 87 FR 4503 (January 28, 2022).
    \33\ Id at 4506.
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    On July 22, 2021, the EPA proposed to partially approve and 
partially disapprove portions of the 2018 PM2.5 Plan that 
address attainment of the 1997 annual PM2.5 NAAQS in the San 
Joaquin Valley nonattainment area.\34\ The EPA proposed to approve the 
2013 base year emissions inventories and disapprove the attainment 
demonstration and related elements, including the comprehensive 
precursor demonstration, five percent annual emissions reductions 
demonstration, best available control measures (BACM) demonstration, 
RFP demonstration, quantitative milestones, and motor vehicle emission 
budgets established for 2017, 2020, and 2023. We proposed to disapprove 
the attainment demonstration and related elements because certified air 
quality data were available that established that the San Joaquin 
Valley area did not attain the 1997 annual PM2.5 NAAQS by 
December 31, 2020, as projected in the 2018 PM2.5 Plan. The 
EPA also proposed to disapprove the contingency measures element 
because of several identified deficiencies, including that the measure 
did not address the potential for failures to meet RFP, to meet a 
quantitative milestone, or to submit a quantitative milestone 
report.\35\ On November 26, 2021, the EPA finalized the partial 
approval and partial disapproval of the 2018 PM2.5 Plan for 
the 1997 annual PM2.5 NAAQS as proposed.\36\
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    \34\ 86 FR 38652.
    \35\ Id. at 38669.
    \36\ 86 FR 67329.
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    As a result of the November 26, 2021 disapprovals, California was 
required to develop and submit a revised attainment plan for the San 
Joaquin Valley area that addresses the applicable CAA requirements, 
including the Serious area plan requirements and the requirements of 
CAA section 189(d), for the 1997 annual PM2.5 NAAQS. In 
accordance with sections 179(d)(3) and 172(a)(2) of the CAA, the 
revised plan must demonstrate attainment of these NAAQS as 
expeditiously as practicable and no later than 5 years from the date of 
the EPA's prior determination that the area failed to attain (i.e., by 
November 23, 2021), except that the EPA may extend the attainment date 
to a date no later than 10 years from the date of this determination 
(i.e., to November 23, 2026), ``considering the severity of 
nonattainment and the availability and feasibility of pollution control 
measures.'' \37\
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    \37\ 81 FR 84481, 84482 (final EPA action determining that the 
San Joaquin Valley had failed to attain the 1997 PM2.5 
NAAQS by the December 31, 2015, Serious area attainment date).
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    On November 8, 2021, CARB submitted the ``Attainment Plan Revision 
for the 1997 Annual PM2.5 Standard'' (``15 [micro]g/m\3\ SIP 
Revision''), adopted by the SJVUAPCD on August 19, 2021, and adopted by 
CARB on September 23, 2021.\38\ In the letter

[[Page 45279]]

accompanying the submission, CARB clarifies that the 15 [micro]g/m\3\ 
SIP Revision amends the 2018 PM2.5 Plan and addresses all 
CAA requirements for the 1997 annual PM2.5 NAAQS except for 
contingency measures, which CARB stated it will address at a later 
date.\39\
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    \38\ Letter dated November 8, 2021, from Richard W. Corey, 
Executive Officer, CARB, to Deborah Jordan, Acting Regional 
Administrator, EPA Region 9. The 15 [micro]g/m\3\ SIP Revision was 
developed jointly by CARB and the District.
    \39\ Id. at 1.
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II. Summary and Completeness Review of the San Joaquin Valley PM2.5 
Plan

    We are proposing action on those portions of the 15 [micro]g/m\3\ 
SIP Revision, 2018 PM2.5 Plan, and Valley State SIP Strategy 
that pertain to the 1997 annual PM2.5 NAAQS. Herein, we 
refer to these three submissions collectively as the ``SJV 
PM2.5 Plan'' or ``Plan.'' The SJV PM2.5 Plan 
addresses Serious area nonattainment plan and CAA section 189(d) 
requirements for the 1997 annual PM2.5 NAAQS in the San 
Joaquin Valley, including the State's demonstration that the area will 
attain the 1997 annual PM2.5 NAAQS by December 31, 2023.

A. 2018 PM2.5 Plan and 15 [micro]g/m\3\ SIP Revision

    CARB and the District describe the 15 [micro]g/m\3\ SIP Revision as 
an ``administrative revision'' to the 2018 PM2.5 Plan that 
``has been prepared as a streamlined document that utilizes the 
existing emissions inventory, air quality analysis and modeling from 
the 2018 PM2.5 Plan.'' \40\ In its submission of the 15 
[micro]g/m\3\ SIP Revision to the EPA, the State included a redline 
strikeout version highlighting the updates that were made relative to 
the 2018 PM2.5 Plan submitted on May 10, 2019, as well as 
final versions of those sections that were revised relative to the 2018 
PM2.5 Plan.
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    \40\ 15 [micro]g/m\3\ SIP Revision, p. 5.
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    The State updated the following portions of the 2018 
PM2.5 Plan and resubmitted them to the EPA as the 15 
[micro]g/m\3\ SIP Revision to address both the Serious area 
requirements in CAA section 189(b) and the CAA section 189(d) 
requirements for the 1997 annual PM2.5 NAAQS in the San 
Joaquin Valley: (i) Chapter 4 (``Attainment Strategy for 
PM2.5''); (ii) Chapter 5 (``Demonstration of Federal 
Requirements for 1997 PM2.5 Standards''); (iii) Appendix D 
(``Mobile Source Control Measure Analyses''); (iv) Appendix H (``RFP, 
Quantitative Milestones, and Contingency''); and (v) Appendix K 
(``Modeling Attainment Demonstration''). The November 8, 2021 submittal 
package also included CARB's ``Staff Report, Proposed SIP Revision for 
the 15 ug/m3 Annual PM2.5 Standard for the San Joaquin 
Valley,'' release date August 13, 2021 (``August 2021 Staff 
Report''),\41\ and the State's and District's board resolutions 
adopting the 15 [micro]g/m\3\ SIP Revision (CARB Resolution 21-21 and 
SJVUAPCD Governing Board Resolution 21-08-13).\42\
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    \41\ CARB's August 2021 Staff Report includes CARB's review of, 
among other things, the control strategy in the 15 [micro]g/m\3\ SIP 
Revision and assessment of the differences between the emissions 
inventories in the Plan and updated inventories more recently 
developed by CARB.
    \42\ CARB Resolution 21-21, ``San Joaquin Valley State 
Implementation Plan Revision for the 15 [mu]g/m\3\ Annual 
PM2.5 Standard,'' September 23, 2021, and SJVUAPCD 
Governing Board Resolution 21-08-13, ``Adopting the San Joaquin 
Valley Unified Air Pollution Control District Proposed Attainment 
Plan Revision For the 1997 Annual PM2.5 Standard,'' 
August 19, 2021.
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    The portions of the Plan that address the requirements for the 1997 
annual PM2.5 NAAQS and that the State did not revise 
relative to the 2018 PM2.5 Plan include: (i) Appendix A 
(``Ambient PM2.5 Data Analysis''); (ii) Appendix B 
(``Emissions Inventory''); (iii) Appendix C (``Stationary Source 
Control Measure Analyses''); (iv) Appendix G (``Precursor 
Demonstration''); (v) Appendix I (``New Source Review and Emission 
Reduction Credits''); (vi) Appendix J (``Modeling Emission 
Inventory''); and (vii) Appendix L (``Modeling Protocol''). The May 10, 
2019 submittal package also included CARB's ``Staff Report, Review of 
the San Joaquin Valley 2018 Plan for the 1997, 2006, and 2012 
PM2.5 Standards,'' release date December 21, 2018 
(``December 2018 Staff Report''); \43\ and the State's and District's 
board resolutions adopting the 2018 PM2.5 Plan (CARB 
Resolution 19-1 and SJVUAPCD Governing Board Resolution 18-11-16).\44\
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    \43\ Letter dated December 11, 2019, from Richard Corey, 
Executive Officer, CARB, to Mike Stoker, Regional Administrator, EPA 
Region 9, transmitting the December 2018 Staff Report. The December 
2018 Staff Report includes CARB's review of, among other things, the 
2018 PM2.5 Plan's control strategy and attainment 
demonstration.
    \44\ CARB Resolution 19-1, ``2018 PM2.5 State 
Implementation Plan for the San Joaquin Valley,'' January 24, 2019, 
and SJVUAPCD Governing Board Resolution 18-11-16, ``Adopting the 
[SJVUAPCD] 2018 Plan for the 1997, 2006, and 2012 PM2.5 
Standards,'' November 15, 2018.
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    As noted above, the 2018 PM2.5 Plan incorporates by 
reference the Valley State SIP Strategy. For the purposes of this 
action, the relevant portions of the Valley State SIP Strategy are the 
mobile source control measure commitments associated with the 
quantitative milestones for the 1997 annual PM2.5 NAAQS.

B. Procedural Requirements for SIPs and SIP Revisions

    CAA sections 110(a)(1) and (2) and 110(l) require each state to 
provide reasonable public notice and opportunity for public hearing 
prior to the adoption and submission of a SIP or SIP revision to the 
EPA. To meet this requirement, every SIP submission 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.
    Both the District and CARB satisfied the applicable statutory and 
regulatory requirements for reasonable public notice and hearing prior 
to adoption and submission of the 2018 PM2.5 Plan and 15 
[micro]g/m\3\ SIP Revision. The District provided public notice and 
opportunity for public comment prior to its November 15, 2018 public 
hearing on and adoption of the 2018 PM2.5 Plan.\45\ CARB 
also provided public notice and opportunity for public comment prior to 
its January 24, 2019 public hearing on and adoption of the 2018 
PM2.5 Plan.\46\ Subsequently, the District provided public 
notice and opportunity for public comment prior to its August 19, 2021 
public hearing on and adoption of the 15 [micro]g/m\3\ SIP 
Revision.\47\ CARB also provided public notice and opportunity for 
public comment prior to its September 23, 2021 public hearing on and 
adoption of the 15 [micro]g/m\3\ SIP Revision.\48\ The SIP submissions 
include proof of publication of notices for the respective public 
hearings. They also include copies of the written and oral comments 
received during the State's and District's public review processes and 
the agencies' responses thereto.49 50 Therefore, we find 
that the

[[Page 45280]]

2018 PM2.5 Plan and 15 [micro]g/m\3\ SIP Revision meet the 
procedural requirements for public notice and hearing in CAA sections 
110(a) and 110(l) and 40 CFR 51.102.
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    \45\ SJVUAPCD, ``Notice of Public Hearing for Adoption of 
Proposed 2018 PM2.5 Plan for the 1997, 2006, and 2012 
Standards,'' October 16, 2018, and SJVUAPCD Governing Board 
Resolution 18-11-16.
    \46\ CARB, ``Notice of Public Meeting to Consider the 2018 
PM2.5 State Implementation Plan for the San Joaquin 
Valley,'' December 21, 2018, and CARB Resolution 19-1.
    \47\ SJVUAPCD, ``Notice of Public Hearing: Adopt Attainment Plan 
Revision for the 1997 Annual PM2.5 Standard,'' July 20, 
2021, and SJVUAPCD Governing Board Resolution 21-08-13.
    \48\ CARB, ``Notice of Public Meeting to Hear an Update on the 
2018 PM2.5 State Implementation Plan for the San Joaquin 
Valley and Consider a State Implementation Plan Revision for the 15 
[micro]g/m\3\ Annual PM2.5 Standard,'' September 23, 
2021, and CARB Resolution 21-21.
    \49\ CARB, ``Board Meeting Comments Log,'' March 29, 2019; J&K 
Court Reporting, LLC, ``Meeting, State of California Air Resources 
Board,'' January 24, 2019 (transcript of CARB's public hearing), and 
2018 PM2.5 Plan, Appendix M (``Summary of Significant 
Comments and Responses'').
    \50\ CARB, ``Board Meeting Comments Log,'' September 23, 2021; 
J&K Court Reporting, LLC, ``Videoconference Meeting, State of 
California Air Resources Board,'' September 23, 2021 (transcript of 
CARB's public hearing).
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    CAA section 110(k)(1)(B) requires the EPA to determine whether a 
SIP submission is complete within 60 days of receipt. This section also 
provides that any plan that the EPA has not affirmatively determined to 
be complete or incomplete will become complete by operation of law six 
months after the date of submission. The EPA's SIP completeness 
criteria are found in 40 CFR part 51, Appendix V.
    We have reviewed the 15 [micro]g/m\3\ SIP Revision for completeness 
and find that it meets the completeness criteria in 40 CFR part 51 
Appendix V. On May 8, 2022, the 15 [micro]g/m\3\ SIP Revision was 
deemed complete by operation of law under CAA section 110(k)(1)(B). The 
2018 PM2.5 Plan and Valley State SIP Strategy became 
complete by operation of law on November 10, 2019, and the EPA 
subsequently issued a letter making an affirmative completeness finding 
and terminating the sanctions clocks under CAA section 179(a) on June 
24, 2020.\51\
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    \51\ Letter dated June 24, 2020, from Elizabeth J. Adams, 
Director, Air and Radiation Division, EPA Region IX, to Richard 
Corey, Executive Officer, CARB, Subject: ``RE: Completeness Finding 
for State Implementation Plan (SIP) Submissions for San Joaquin 
Valley for the 1997, 2006, and 2012 Fine Particulate Matter 
(PM2.5) National Ambient Air Quality Standards (NAAQS) 
and Termination of Clean Air Act (CAA) Sanction Clocks.''
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III. Clean Air Act Requirements for PM2.5 Serious Area Plans and for 
Serious PM2.5 Areas That Fail To Attain

A. Requirements for PM2.5 Serious Area Plans

    Upon reclassification of a Moderate nonattainment area as a Serious 
nonattainment area under subpart 4 of part D, title I of the CAA, the 
Act requires the state to make a SIP submission that addresses the 
following Serious nonattainment area requirements: \52\
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    \52\ 40 CFR 51.1003(b)(1); 81 FR 58010, 58074-58075 (August 24, 
2016).
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    1. A comprehensive, accurate, current inventory of actual emissions 
from all sources of PM2.5 and PM2.5 precursors in 
the area (CAA section 172(c)(3));
    2. Provisions to assure that BACM, including best available control 
technology (BACT), for the control of direct PM2.5 and 
PM2.5 precursors shall be implemented no later than four 
years after the area is reclassified (CAA section 189(b)(1)(B)), unless 
the state elects to make an optional precursor demonstration that the 
EPA approves authorizing the state not to regulate one or more of these 
pollutants;
    3. A demonstration (including air quality modeling) that the plan 
provides for attainment as expeditiously as practicable but no later 
than the end of the tenth calendar year after designation as a 
nonattainment area (i.e., December 31, 2015, for the San Joaquin Valley 
for the 1997 PM2.5 NAAQS);
    4. Plan provisions that require RFP (CAA section 172(c)(2));
    5. Quantitative milestones that are to be achieved every three 
years until the area is redesignated attainment and that demonstrate 
RFP toward attainment by the applicable date (CAA section 189(c));
    6. Provisions to assure that control requirements applicable to 
major stationary sources of PM2.5 also apply to major 
stationary sources of PM2.5 precursors, except where the 
state demonstrates to the EPA's satisfaction that such sources do not 
contribute significantly to PM2.5 levels that exceed the 
standard in the area (CAA section 189(e));
    7. Contingency measures to be implemented if the area fails to meet 
RFP or to attain by the applicable attainment date (CAA section 
172(c)(9)); and
    8. A revision to the nonattainment new source review (NSR) program 
to lower the applicable ``major stationary source'' \53\ thresholds 
from 100 tons per year (tpy) to 70 tpy (CAA section 189(b)(3)).
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    \53\ For any Serious area, the terms ``major source'' and 
``major stationary source'' include any stationary source that emits 
or has the potential to emit at least 70 tons per year of 
PM2.5. CAA section 189(b)(3) and 40 CFR 
51.165(a)(1)(iv)(A)(1)(vii) and (viii) (defining ``major stationary 
source'' in Serious PM2.5 nonattainment areas).
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    A state's Serious area plan must also satisfy the requirements for 
Moderate area plans in CAA section 189(a), to the extent the state has 
not already met those requirements in the Moderate area plan submitted 
for the area. In addition, the Serious area plan must meet the general 
requirements applicable to all SIP submissions under section 110 of the 
CAA, including the requirement to provide necessary assurances that the 
implementing agencies have adequate personnel, funding, and authority 
under section 110(a)(2)(E); and the requirements concerning enforcement 
provisions in section 110(a)(2)(C).

B. Requirements for Serious PM2.5 Areas That Fail To Attain

    In the event that a Serious area fails to attain the 
PM2.5 NAAQS by the applicable attainment date, CAA section 
189(d) requires that ``the State in which such area is located shall, 
after notice and opportunity for public comment, submit within 12 
months after the applicable attainment date, plan revisions which 
provide for attainment of the . . . standard . . .'' An attainment plan 
under section 189(d) must, among other things, demonstrate expeditious 
attainment of the NAAQS within the time period provided under CAA 
section 179(d)(3) and provide for annual reductions in emissions of 
direct PM2.5 or a PM2.5 plan precursor pollutant 
within the area of not less than five percent per year from the most 
recent emissions inventory for the area until attainment.\54\
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    \54\ CAA section 189(d), 40 CFR 51.1004(a)(3), 40 CFR 
51.1010(c).
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    In addition to the requirement to submit control measures providing 
for a five percent reduction in emissions of certain pollutants on an 
annual basis, the EPA interprets CAA section 189(d) as requiring a 
state to submit an attainment plan that includes the same basic 
statutory plan elements that are required for other attainment 
plans.\55\ Specifically, a state must submit to the EPA its plan to 
meet the requirements of CAA section 189(d) in the form of a complete 
attainment plan submission that includes the following elements: \56\
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    \55\ 81 FR 58010, 58098.
    \56\ 40 CFR 51.1003(c)(1).
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    1. A comprehensive, accurate, current inventory of actual emissions 
from all sources of PM2.5 and PM2.5 precursors in 
the area;
    2. A Serious area plan control strategy that ensures that BACM, 
including BACT, for the control of direct PM2.5 and 
PM2.5 precursors are implemented in the area, unless the 
state elects to make an optional precursor demonstration that the EPA 
approves authorizing the state not to regulate one or more of these 
pollutants;
    3. Additional measures (beyond those already adopted in previous 
nonattainment plan SIP submissions for the area as RACM/RACT, BACM/
BACT, and most stringent measures (MSM) (if applicable) \57\) that 
provide for attainment of the NAAQS as expeditiously as practicable 
and, from the date of such submission until attainment, demonstrate 
that the plan will, at a minimum, achieve an annual five percent 
reduction in emissions of direct PM2.5 or any 
PM2.5 plan precursor;
---------------------------------------------------------------------------

    \57\ MSM is applicable if the EPA has previously granted an 
extension of the attainment date under CAA section 188(e) for the 
nonattainment area and NAAQS at issue.
---------------------------------------------------------------------------

    4. A demonstration (including air quality modeling) that the plan 
provides

[[Page 45281]]

for attainment of the NAAQS at issue as expeditiously as practicable;
    5. Plan provisions that require RFP;
    6. Quantitative milestones that the state is to meet every three 
years until the area is redesignated attainment and that demonstrate 
RFP toward attainment by the applicable date;
    7. Contingency measures to be implemented if the state fails to 
meet any requirement concerning RFP or quantitative milestones or to 
attain the NAAQS at issue by the applicable attainment date; and
    8. Provisions to assure that control requirements applicable to 
major stationary sources of PM2.5, also apply to major 
stationary sources of PM2.5 precursors, except where the 
state demonstrates to the EPA's satisfaction that such sources do not 
contribute significantly to PM2.5 levels that exceed the 
NAAQS at issue in the area.
    A state's section 189(d) plan submission must demonstrate 
attainment as expeditiously as practicable, and no later than 5 years 
from the date of the EPA's determination that the area failed to 
attain, except that the Administrator may extend the attainment date to 
no later than 10 years from the failure to attain determination, 
consistent with sections 179(d)(3) and 172(a)(2) of the CAA.\58\
---------------------------------------------------------------------------

    \58\ 81 FR 84481, 84482.
---------------------------------------------------------------------------

    A state with a Serious PM2.5 nonattainment area that 
fails to attain the NAAQS by the applicable Serious area attainment 
date must also address any statutory requirements applicable to 
Moderate and Serious nonattainment area plans under CAA sections 172 
and 189 of the CAA to the extent that those requirements have not 
already been met.\59\ Because the EPA has not previously approved a SIP 
submission for the San Joaquin Valley as meeting the subpart 4 RACM 
Moderate area planning requirements under CAA section 189 for the 1997 
annual PM2.5 NAAQS, the EPA is evaluating relevant portions 
of the SJV PM2.5 Plan for compliance with this requirement. 
In addition, as discussed above, the EPA has not previously approved a 
SIP submission for the San Joaquin Valley as meeting the Serious area 
planning requirements under CAA section 189(b)(1) for the 1997 annual 
PM2.5 NAAQS. Some Serious area planning requirements operate 
on a timeline that is based on the outermost statutory Serious area 
attainment date of the end of the tenth calendar year following the 
area's designation to nonattainment. Because section 189(d) requires a 
state to address any applicable Serious area requirements that the 
state has not already met in the area, and the section 189(d) 
obligations do not come into effect until an area has failed to attain 
the NAAQS by the Serious area attainment date, the EPA is evaluating 
any previously unmet Serious area planning obligations based on the 
current, applicable attainment date appropriate under section 189(d), 
and not the original Serious area attainment date.\60\
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    \59\ 81 FR 58010, 58098.
    \60\ See, e.g., 86 FR 53150 (September 24, 2021) and 87 FR 4503 
(January 28, 2022) (proposed and final actions evaluating a 
previously unmet Serious area planning obligation based on the 
applicable attainment date under section 189(d), not the original 
Serious area attainment date).
---------------------------------------------------------------------------

    The EPA provided its preliminary views on the CAA's requirements 
for particulate matter plans under part D, title I of the Act in the 
following guidance documents: (1) ``State Implementation Plans; General 
Preamble for the Implementation of Title I of the Clean Air Act 
Amendments of 1990'' (``General Preamble''); \61\ (2) ``State 
Implementation Plans; General Preamble for the Implementation of Title 
I of the Clean Air Act Amendments of 1990; Supplemental''; \62\ and (3) 
``State Implementation Plans for Serious PM-10 Nonattainment Areas, and 
Attainment Date Waivers for PM-10 Nonattainment Areas Generally; 
Addendum to the General Preamble for the Implementation of Title I of 
the Clean Air Act Amendments of 1990'' (``General Preamble 
Addendum'').\63\ More recently, in an August 24, 2016 final rule 
entitled, ``Fine Particulate Matter National Ambient Air Quality 
Standards: State Implementation Plan Requirements'' (``PM2.5 
SIP Requirements Rule''), the EPA established regulatory requirements 
and provided further interpretive guidance on the statutory SIP 
requirements that apply to areas designated nonattainment for the 
PM2.5 NAAQS.\64\ We discuss these regulatory requirements 
and interpretations of the Act as appropriate in our evaluation of the 
SJV PM2.5 Plan that follows.
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    \61\ 57 FR 13498 (April 16, 1992).
    \62\ 57 FR 18070 (April 28, 1992).
    \63\ 59 FR 41998 (August 16, 1994).
    \64\ 81 FR 58010.
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IV. Review of the San Joaquin Valley PM2.5 Plan for the 1997 Annual 
PM2.5 NAAQS

    The EPA is evaluating the SJV PM2.5 Plan against the 
Serious area requirements for the 1997 annual PM2.5 NAAQS 
and the section 189(d) requirements for the 1997 annual 
PM2.5 NAAQS, as laid out in Section III of this document. 
Many requirements for both a Serious area plan and a section 189(d) 
plan are structured around the relevant statutory attainment date. The 
latest statutory Serious area attainment date for the San Joaquin 
Valley area was December 31, 2015.\65\ On November 23, 2016, the EPA 
determined that the area failed to attain by the Serious area 
attainment date.
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    \65\ As discussed in Section I.B of this proposal, California 
submitted its Serious area plan for the 1997 annual PM2.5 
NAAQS in two submissions dated June 25, 2015 and August 13, 2015, 
including a request under section 188(e) to extend the attainment 
date for the 1997 annual PM2.5 NAAQS by five years (to 
December 31, 2020). On October 6, 2016, the EPA denied the request 
for an extension, but did not finalize action on the Serious area 
plan submissions. Accordingly, the Serious area attainment date 
remained unchanged: as expeditiously as practicable but no later 
than December 31, 2015.
---------------------------------------------------------------------------

    For the purposes of the section 189(d) requirements, the attainment 
date is the date by which a state can attain the NAAQS as expeditiously 
as practicable, but no later than 5 years from the publication date of 
the final determination of failure to attain, except that the EPA may 
extend the attainment date to a date no later than 10 years from the 
date of the determination (i.e., to November 23, 2026), ``considering 
the severity of nonattainment and the availability and feasibility of 
pollution control measures.'' \66\ The SJV PM2.5 Plan 
projects that attainment will be achieved by December 31, 2023, 
approximately seven years after the determination of failure to attain. 
The EPA is proposing to approve the SJV PM2.5 Plan's 
attainment date in this action.
---------------------------------------------------------------------------

    \66\ CAA section 172(a)(2) and 179(d)(3); 81 FR 84481, 84482. 
The determination of failure to attain published on November 23, 
2016.
---------------------------------------------------------------------------

    When the State submitted the 2018 PM2.5 Plan in 2019, 
the State withdrew its previous Serious area plan that it had developed 
to meet the December 31, 2015 Serious area attainment date. Because the 
State submitted the 2018 PM2.5 Plan and subsequent 15 
[micro]g/m\3\ SIP Revision after the EPA's finding that the area had 
failed to attain by the applicable Serious area attainment date, the 
State could not demonstrate that the area would attain by the Serious 
area attainment date, nor could it address other requirements based on 
this attainment date, such as RFP and quantitative milestones, because 
many of the relevant dates had already passed. As described in Section 
III of this document, in a section 189(d) plan, a state must address 
any statutory requirements applicable to Moderate and Serious 
nonattainment area plans to the extent that it has not already met 
those requirements, but the EPA

[[Page 45282]]

believes that it should base this evaluation on the current applicable 
attainment date under section 189(d). For example, it would be 
illogical to require a state to submit a Serious area modeled 
attainment demonstration that provided for attainment by December 31, 
2015, after the EPA has already determined based on monitoring data 
that the state failed to attain by such date.
    For the purposes of our evaluation of the Serious area plan 
requirements, although the State is required to submit a Serious area 
plan and it must structure such a plan based on the Serious area 
attainment date, it would serve no purpose to evaluate the SJV 
PM2.5 Plan against the now-passed Serious area attainment 
date by which the area has already failed to attain. For example, RFP 
and quantitative milestones normally are dependent upon the attainment 
date. Accordingly, because the State must still meet all Serious area 
plan requirements, even if doing so later in conjunction with the 
section 189(d) plan and its later attainment date, we will evaluate the 
State's compliance with the Serious area plan requirements in light of 
the later section 189(d) attainment date, as appropriate. Where the 
State in the SJV PM2.5 Plan applies the section 189(d) 
attainment date to a Serious area requirement, we will note the 
statutory Serious area timeline and accept the submission in 
fulfillment of the State's Serious area plan obligation but evaluate 
the submission in light of the section 189(d) attainment date.

A. Emissions Inventories

1. Statutory and Regulatory Requirements
    CAA section 172(c)(3) requires that each SIP include a 
comprehensive, accurate, current inventory of actual emissions from all 
sources of the relevant pollutant or pollutants in the nonattainment 
area. The EPA discussed the emissions inventory requirements that apply 
to PM2.5 nonattainment areas in the PM2.5 SIP 
Requirements Rule and codified these requirements in 40 CFR 
51.1008.\67\ The EPA has also issued guidance concerning emissions 
inventories for PM2.5 nonattainment areas.\68\
---------------------------------------------------------------------------

    \67\ 81 FR 58010, 58098-58099.
    \68\ ``Emissions Inventory Guidance for Implementation of Ozone 
and Particulate Matter National Ambient Air Quality Standards 
(NAAQS) and Regional Haze Regulations,'' U.S. EPA, May 2017 
(``Emissions Inventory Guidance''), available at https://www.epa.gov/air-emissions-inventories/air-emissions-inventory-guidance-implementation-ozone-and-particulate.
---------------------------------------------------------------------------

    The base year emissions inventory for a Serious area attainment 
plan or a CAA section 189(d) plan must provide a state's best estimate 
of actual emissions from all sources of the relevant pollutants in the 
area, i.e., all emissions that contribute to the formation of a 
particular NAAQS pollutant. For the PM2.5 NAAQS, the base 
year inventory must include direct PM2.5 emissions, 
separately reported filterable and condensable PM2.5 
emissions,\69\ and emissions of all chemical precursors to the 
formation of secondary PM2.5, i.e., nitrogen oxides 
(NOX), sulfur dioxide (SO2), volatile organic 
compounds (VOC), and ammonia.\70\
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    \69\ The Emissions Inventory Guidance identifies the types of 
sources for which the EPA expects states to provide condensable PM 
emissions inventories. Emissions Inventory Guidance, Section 4.2.1 
(``Condensable PM Emissions''), pp. 63-65.
    \70\ 40 CFR 51.1008(b)(1) and (c)(1).
---------------------------------------------------------------------------

    The emissions inventory base year for a Serious area attainment 
plan must be one of the three years for which monitoring data were used 
to reclassify the area to Serious, or another technically appropriate 
year justified by the state in its Serious area SIP submission.\71\ The 
emissions inventory base year for a Serious PM2.5 
nonattainment area subject to CAA section 189(d) must be one of the 
three years for which the EPA used monitored data to determine that the 
area failed to attain the PM2.5 NAAQS by the applicable 
Serious area attainment date, or another technically appropriate year 
justified by the state in its Serious area SIP submission.\72\
---------------------------------------------------------------------------

    \71\ 40 CFR 51.1008(b)(1).
    \72\ 40 CFR 51.1008(c)(1).
---------------------------------------------------------------------------

    A state's SIP submission must include documentation explaining how 
it calculated emissions data for the inventory. In estimating mobile 
source emissions, a state should use the latest emissions models and 
planning assumptions available at the time the SIP is developed.
    In addition to the base year inventory submitted to meet the 
requirements of CAA section 172(c)(3), the state must also submit a 
projected attainment year inventory and emissions projections for each 
RFP milestone year.\73\ These future emissions projections are 
necessary components of the attainment demonstrations required under 
CAA sections 189(b)(1) and 189(d) and the demonstration of RFP required 
under section 172(c)(2).\74\ Emissions projections for future years 
(referred to in the Plan as ``forecasted inventories'') should account 
for, among other things, the ongoing effects of economic growth and 
adopted emissions control requirements. The state's SIP submission 
should include documentation to explain how the state calculated the 
emissions projections. Where a state chooses to allow new major 
stationary sources or major modifications to use emissions reduction 
credits (ERCs) that were generated through shutdown or curtailed 
emissions units occuring before the base year of an attainment plan, 
the projected emissions inventory used to develop the attainment 
demonstration must explicitly include the emissions from such 
previously shutdown or curtailed emissions units.\75\
---------------------------------------------------------------------------

    \73\ 40 CFR 51.1008 and 51.1012. See also Emissions Inventory 
Guidance, Section 3 (``SIP Inventory Requirements and 
Recommendations'').
    \74\ 40 CFR 51.1004, 51.1008, 51.1011, and 51.1012.
    \75\ 40 CFR 51.165(a)(3)(ii)(C)(1).
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2. Summary of the State's Submission
    The State included summaries of the planning emissions inventories 
for direct PM2.5 and PM2.5 precursors 
(NOX, SOX,\76\ VOC,\77\ and ammonia) and the 
documentation for the inventories for the San Joaquin Valley 
PM2.5 nonattainment area in Appendix B (``Emissions 
Inventory'') and Appendix I (``New Source Review and Emission Reduction 
Credits'') of the 2018 PM2.5 Plan. In addition, Appendix J 
(``Modeling Emission Inventory'') of the 2018 PM2.5 Plan 
contains inventory documentation specific to the air quality modeling 
inventories.
---------------------------------------------------------------------------

    \76\ The SJV PM2.5 Plan generally uses ``sulfur 
oxides'' or ``SOX'' in reference to SO2 as a 
precursor to the formation of PM2.5. We use 
SOX and SO2 interchangeably throughout this 
document.
    \77\ The SJV PM2.5 Plan generally uses ``reactive 
organic gasses'' or ``ROG'' in reference to VOC as a precursor to 
the formation of PM2.5. We use ROG and VOC 
interchangeably throughout this document.
---------------------------------------------------------------------------

    CARB and District staff worked together to develop the emissions 
inventories for the San Joaquin Valley PM2.5 nonattainment 
area. The District worked with operators of the stationary facilities 
in the nonattainment area to develop the stationary source emissions 
estimates. The responsibility for developing emissions estimates for 
area sources such as agricultural burning and paved road dust was 
shared by the District and CARB. CARB staff developed the emissions 
inventories for both on-road and non-road mobile sources.\78\
---------------------------------------------------------------------------

    \78\ The EPA regulations refer to ``non-road'' vehicles and 
engines whereas CARB regulations refer to ``Other Mobile Sources'' 
or ``off-road'' vehicles and engines. These terms refer to the same 
types of vehicles and engines. We refer herein to such vehicles and 
engines as ``non-road'' sources.
---------------------------------------------------------------------------

    The SJV PM2.5 Plan includes winter (24-hour) average and 
annual average daily emissions inventories for the 2013 base year, 
which CARB derived from the 2012 emissions inventory, and

[[Page 45283]]

estimated emissions for forecasted years from 2017 through 2028, as 
developed as part of the 2018 PM2.5 Plan for the attainment 
and RFP demonstrations for the 1997, 2006, and 2012 PM2.5 
NAAQS.\79\ In this proposal, we are evaluating those winter average and 
annual average emissions inventories necessary to support the Serious 
area and CAA section 189(d) nonattainment plans for the 1997 annual 
PM2.5 NAAQS, i.e., the 2013 base year inventory, forecasted 
inventories for the RFP milestone years of 2017, 2020, 2023 (attainment 
year), and 2026 (post-attainment milestone year), and additional 
forecasted emissions inventories for 2018, 2019, 2021, and 2022 to 
support the five percent annual emissions reduction demonstration as 
required by CAA section 189(d). Each inventory includes emissions from 
stationary, area, on-road, and non-road sources.
---------------------------------------------------------------------------

    \79\ 2018 PM2.5 Plan, Appendix B, pp. B-18 to B-19. 
The winter average daily planning inventory corresponds to the 
months of November through April, when daily ambient 
PM2.5 concentrations are typically highest. The base year 
inventory is from the California Emissions Inventory Development and 
Reporting System and future year inventories were estimated using 
the California Emission Projection Analysis Model (CEPAM), 2016 SIP 
Baseline Emission Projections, version 1.05.
---------------------------------------------------------------------------

    The State selected 2013 for the base year emissions inventory, 
building on the 2012 actual emissions inventory and considering 
available air quality data, trends, and field studies.\80\ 
Specifically, the State worked with local air districts and selected 
2012 for the actual emissions inventory as it aligned with the 2012 
data collection year of the Multiple Air Toxics Exposure Study IV 
(MATES IV) \81\ of the South Coast Air Quality Management District 
(SCAQMD) and to maintain consistency across various California air 
quality plans.\82\ The State then projected the 2013 base year 
emissions inventory (also referred to as the planning emissions 
inventory), presented in Appendix B of the 2018 PM2.5 Plan, 
from that 2012 actual emissions inventory. The State developed the 
modeling emissions inventory from the base year emissions inventory, 
and conducted its base case modeling using 2013 for several reasons: 
Analysis of air quality trends, adjusted for meteorology, that 
indicated 2013 as a year conducive to ozone and PM2.5 
formation; availability of research-grade measurements of two 
significant pollution episodes in the DISCOVER-AQ field study of 
January to February 2013; and the relatively high design values for 
2013, making it a conservative choice for attainment modeling.\83\
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    \80\ 2018 PM2.5 Plan, Appendix L, pp. 11-12.
    \81\ Additional information on the MATES IV study performed in 
2012 is available at: https://www.aqmd.gov/home/air-quality/air-quality-studies/health-studies/mates-iv. SCAQMD performed the 
subsequent MATES V study in 2018 and issued the MATES V final report 
in August 2021. See https://www.aqmd.gov/home/air-quality/air-quality-studies/health-studies/mates-v, and ``MATES V, Multiple Air 
Toxics Exposure Study in the South Coast AQMD, Final Report,'' 
SCAQMD, August 2021.
    \82\ 2018 PM2.5 Plan, Appendix B, p. B-18
    \83\ 2018 PM2.5 Plan, Appendix L, p. 12. The State 
presents further information in the ``APPENDIX: San Joaquin Valley 
PM2.5 SIP (2018)'' of Appendix L and highlights that 2013 
was one of the worst years in the decade preceding 2018 for 
PM2.5 pollution in the San Joaquin Valley, underscoring 
its use as a conservative base year for attainment modeling.
---------------------------------------------------------------------------

    CARB developed the base year inventories for stationary sources 
using actual emissions reports from facility operators. The State 
developed the base year emissions inventory for area sources using the 
most recent models and methodologies available at the time the State 
was developing the 2018 PM2.5 Plan.\84\ The Plan also 
includes background, methodology, and inventories of condensable and 
filterable PM2.5 emissions from stationary point and non-
point combustion sources that are expected to generate condensable 
PM2.5.\85\
---------------------------------------------------------------------------

    \84\ 2018 PM2.5 Plan, Appendix B, Section B.2 
(``Emissions Inventory Summary and Methodology'').
    \85\ Id. at B-42 to B-44.
---------------------------------------------------------------------------

    CARB used EMFAC2014 to estimate on-road motor vehicle emissions 
based on transportation activity data from the 2017 Transportation 
Improvement Plan (2017 TIP) adopted by the transportation planning 
agencies in the San Joaquin Valley.\86\ EMFAC2014 was the latest EPA-
approved version of California's mobile source emission factor model 
for estimating tailpipe, brake, and tire wear emissions from on-road 
mobile sources that was available during the State's and District's 
development of the emissions inventories in the 2018 PM2.5 
Plan.\87\ Re-entrained paved road dust emissions were calculated using 
a CARB methodology consistent with the EPA's AP-42 road dust 
methodology.\88\ CARB also provided emissions inventories for non-road 
equipment, including aircraft, trains, recreational boats, construction 
equipment, and farming equipment, among others. CARB uses a suite of 
category-specific models to estimate non-road emissions for many 
categories and, where a new model was not available, used the 
OFFROAD2007 model.\89\
---------------------------------------------------------------------------

    \86\ 2018 PM2.5 Plan, Appendix D, p. D-123.
    \87\ 80 FR 77337 (December 14, 2015). EMFAC is short for 
Emission FACtor. The EPA announced the availability of the EMFAC2014 
model, effective on the date of publication in the Federal Register, 
for use in state implementation plan development and transportation 
conformity in California. Upon that action, EMFAC2014 was required 
to be used for all new regional emissions analyses and CO, 
PM10, and PM2.5 hot-spot analyses that were 
started on or after December 14, 2017, which was the end of the 
grace period for using the prior mobile source emissions model, 
EMFAC2011. On August 15, 2019, the EPA approved EMFAC2017, a 
revision to the mobile source emissions model (84 FR 41717). The 
grace period for new regional emissions analyses began on August 15, 
2019, and ended on August 16, 2021, while the grace period for hot-
spot analyses began on August 15, 2019, and ended on August 17, 
2020. Id. at 41720. On November 15, 2022, the EPA approved 
EMFAC2021, a subsequent revision to the mobile source emissions 
model (87 FR 68483). The grace period for new regional emissions 
analyses began on November 15, 2022, and ends on November 15, 2024, 
while the grace period for hot-spot analyses began on November 15, 
2022, and ends on November 15, 2023. Id. at 68487-68488.
    \88\ 2018 PM2.5 Plan, Appendix B, p. B-28. AP-42 has 
been published since 1972 as the primary source of the EPA's 
emission factor information and is available at https://www.epa.gov/air-emissions-factors-and-quantification/ap-42-compilation-air-emissions-factors. It contains emission factors and process 
information for more than 200 air pollution source categories. A 
source category is a specific industry sector or group of similar 
emitting sources. The emission factors have been developed and 
compiled from source test data, material balance studies, and 
engineering estimates. The EPA released an update to AP-42 in 
January 2011 that revised the equation for estimating paved road 
dust emissions based on an updated data regression that included new 
emissions tests results. 76 FR 6328 (February 4, 2011). CARB used 
the revised 2011 AP-42 methodology in developing on-road mobile 
source emissions; see https://www.arb.ca.gov/ei/areasrc/fullpdf/full7-9_2016.pdf.
    \89\ 2018 PM2.5 Plan, Appendix B, pp. B-38 through B-
40. The EPA regulations refer to ``non-road'' vehicles and engines 
whereas CARB regulations refer to ``Other Mobile Sources'' or ``off-
road'' vehicles and engines. These terms refer to the same types of 
vehicles and engines. We refer herein to such vehicles and engines 
as ``non-road'' sources.
---------------------------------------------------------------------------

    CARB developed the emissions forecasts by applying growth and 
control profiles to the base year inventory. CARB's mobile source 
emissions projections take into account predicted activity rates and 
vehicle fleet turnover by vehicle model year and adopted controls.\90\ 
In addition, the Plan states that the District is providing for use of 
pre-base year ERCs as offsets by accounting for such ERCs in the 
projected 2025 emissions inventory.\91\ The 2018 PM2.5 Plan 
identifies growth factors, control factors, and estimated offset use 
between 2013 and 2025 for direct PM2.5, NOX, 
SOX, and VOC emissions by source category and lists all pre-
base year ERCs issued by the District for PM10, 
NOX, SOX, and VOC emissions, by facility.\92\
---------------------------------------------------------------------------

    \90\ Id. at B-18 and B-19.
    \91\ 2018 PM2.5 Plan, Appendix I, pp. I-1 to I-5.
    \92\ Id. at tables I-1 to I-5.
---------------------------------------------------------------------------

    Table 1 provides a summary of the winter (24-hour) average 
inventories in tons per day (tpd) of direct PM2.5 and 
PM2.5 precursors for the 2013 base year. Table 2 provides a 
summary of annual

[[Page 45284]]

average inventories of direct PM2.5 and PM2.5 
precursors for the 2013 base year. For the purposes of this proposal, 
these annual average inventories provide the bases for our evaluation 
of the precursor demonstration, control measure analysis, attainment 
demonstration, RFP demonstration, and the motor vehicle emission 
budgets (``budgets'') in the SJV PM2.5 Plan with respect to 
the Serious area and CAA section 189(d) requirements for the 1997 
annual PM2.5 NAAQS.

  Table 1--San Joaquin Valley Winter Average Emissions Inventory for Direct PM2.5 and PM2.5 Precursors for the
                                                 2013 Base Year
                                                      [tpd]
----------------------------------------------------------------------------------------------------------------
                                   Direct PM2.5
            Category                                    NOX             SOX             VOC           Ammonia
----------------------------------------------------------------------------------------------------------------
Stationary Sources..............             8.5            35.0             6.9            86.6            13.9
Area Sources....................            41.4            11.5             0.5           156.8           291.5
On-Road Mobile Sources..........             6.4           188.7             0.6            51.1             4.4
Non-Road Mobile Sources.........             4.4            65.3             0.3            27.4             0.0
                                 -------------------------------------------------------------------------------
    Totals \a\..................            60.8           300.5             8.4           321.9           309.8
----------------------------------------------------------------------------------------------------------------
Source: 2018 PM2.5 Plan, Appendix B, tables B-1 to B-5.
\a\ Totals reflect disaggregated emissions and may not add exactly as shown here due to rounding.


  Table 2--San Joaquin Valley Annual Average Emissions Inventory for Direct PM2.5 and PM2.5 Precursors for the
                                                 2013 Base Year
                                                      [tpd]
----------------------------------------------------------------------------------------------------------------
                                   Direct PM2.5
            Category                                    NOX             SOX             VOC           Ammonia
----------------------------------------------------------------------------------------------------------------
Stationary Sources..............             8.8            38.6             7.2            87.1            13.9
Area Sources....................            41.5             8.1             0.3           153.4           310.9
On-Road Mobile Sources..........             6.4           183.1             0.6            49.8             4.4
Non-Road Mobile Sources.........             5.8            87.4             0.3            33.8             0.0
                                 -------------------------------------------------------------------------------
    Totals \a\..................            62.5           317.2             8.5           324.1           329.2
----------------------------------------------------------------------------------------------------------------
Source: 2018 PM2.5 Plan, Appendix B, tables B-1 to B-5.
\a\ Totals reflect disaggregated emissions and may not add exactly as shown here due to rounding.

    CARB explains in its August 2021 Staff Report that although it has 
updated the emissions inventories since development of the 2018 
PM2.5 Plan, the 15 [micro]g/m\3\ SIP Revision ``uses the 
same inventory as the one in the 2018 PM2.5 Plan, which it 
amends, for consistency.'' To support this approach, CARB included in 
its August 2021 Staff Report comparisons between the estimated annual 
NOX and PM2.5 emissions in the 2013 base year 
inventory developed using EMFAC2014 with those developed using the more 
recent EPA-approved version of EMFAC, EMFAC2017. CARB subsequently 
provided similar comparisons for the 2020 RFP and 2023 attainment 
years, as well as comparisons with emissions derived using 
EMFAC2021.\93\ Table 3 shows the comparisons between on-road mobile 
source emissions derived using EMFAC2014, EMFAC2017, and EMFAC2021 for 
NOX and PM2.5 in 2013, 2020, and 2023.
---------------------------------------------------------------------------

    \93\ Email dated March 29, 2022, from Nesamani Kalandiyur, CARB, 
to Karina O'Connor et al., EPA Region IX, Subject: ``RE: EMFAC 
Discussion,'' (``March 2022 EMFAC Clarification''). The email also 
includes model results for the 2026 post-attainment milestone year. 
CARB initially released EMFAC2021 v1.0.0 on January 15, 2021. CARB 
released an updated version, EMFAC2021 v1.0.1, on April 30, 2021, 
and the EPA approved the use of EMFAC2021 for use in SIP development 
on November 15, 2022 (87 FR 68483).

                     Table 3--On-Road Mobile Source NOX and Direct PM2.5 Emissions Derived Using EMFAC2014, EMFAC2017, and EMFAC2021
                                                                          [tpd]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                NOX                                        Direct PM2.5
                                                         -----------------------------------------------------------------------------------------------
                                                               2013            2020            2023            2013            2020            2023
--------------------------------------------------------------------------------------------------------------------------------------------------------
EMFAC2014...............................................           183.1            96.9            57.9             6.5             3.4             3.2
EMFAC2017...............................................           170.0            89.3            61.2             6.8             4.0             3.3
EMFAC2021...............................................           193.5            84.4            54.9             6.1             2.3             1.8
EMFAC2017/EMFAC2014.....................................             93%             92%            106%            106%            116%            105%
EMFAC2021/EMFAC2014.....................................            106%             87%             95%             95%             66%             56%
--------------------------------------------------------------------------------------------------------------------------------------------------------
Source: CARB's March 2022 EMFAC Clarification.

    CARB determined that PM2.5 emissions estimates for 2013 
derived using EMFAC2017 are approximately six percent higher than 
estimates derived using EMFAC2014, and that NOX emissions 
estimates for 2013

[[Page 45285]]

derived using EMFAC2017 are seven percent lower than the emissions 
estimates derived using EMFAC2014. On-road PM2.5 and 
NOX estimates derived using EMFAC2021 are five percent lower 
and six percent higher, respectively, in 2013 as compared with 
estimates from EMFAC2014. In the 2023 attainment year, on-road 
PM2.5 and NOX emissions estimates derived using 
EMFAC2017 are approximately 5 percent and 6 percent higher, 
respectively, than estimates derived using EMFAC2014, whereas on-road 
PM2.5 and NOX emissions estimates derived using 
EMFAC2021 are approximately 44 percent and 5 percent lower, 
respectively, than in EMFAC2014.
    Based on these model results, CARB concludes that the differences 
in emissions derived using the different EMFAC model versions are not 
significant enough to affect the modeled attainment demonstration in 
the 15 [micro]g/m\3\ SIP Revision.
3. The EPA's Review of the State's Submission
    As part of our July 22, 2021 proposed and November 26, 2021 final 
rules,\94\ we reviewed the emissions inventories in the 2018 
PM2.5 Plan that pertain to the 1997 annual PM2.5 
NAAQS and the emissions inventory estimation methodologies used by 
California for consistency with CAA requirements and the EPA's 
guidance. We found that the inventories were based on the most current 
and accurate information available to the State and District at the 
time they were developing the 2018 PM2.5 Plan and 
inventories, including the latest version of California's mobile source 
emissions model that had been approved by the EPA at the time, 
EMFAC2014. We also found that the inventories comprehensively address 
all source categories in the San Joaquin Valley PM2.5 
nonattainment area and are consistent with the EPA's inventory 
guidance. In our November 26, 2021 final action, we approved the 2013 
base year emissions inventories in the 2018 PM2.5 Plan as 
meeting the requirements of CAA section 172(c)(3) and 40 CFR 51.1008 
for purposes of both the Serious area and the CAA section 189(d) 
attainment plans for the 1997 annual PM2.5 NAAQS.\95\
---------------------------------------------------------------------------

    \94\ 86 FR 38652 and 86 FR 67329.
    \95\ 86 FR 67329, 67341.
---------------------------------------------------------------------------

    For purposes of evaluating the 15 [micro]g/m\3\ SIP Revision, we 
have reviewed the additional information comparing the emissions 
derived using EMFAC2014, EMFAC2017, and EMFAC2021 that was provided by 
CARB in its August 2021 Staff Report and subsequent email transmittal. 
The State modeled reductions of direct PM2.5 and 
NOX on-road mobile emissions and calculated the sensitivity 
of the PM2.5 design value per tpd of emissions.\96\ The EPA 
used those sensitivity results with the EMFAC emissions estimates to 
assess the effects of the various EMFAC model version results on the 
attainment demonstration in the Plan. We are proposing to find that 
although NOX and PM2.5 emissions estimates in the 
2023 attainment year are slightly higher in EMFAC2017 than in 
EMFAC2014, the effect on PM2.5 concentrations is small 
enough that the attainment demonstration in the 15 [micro]g/m\3\ SIP 
Revision remains valid.\97\ Furthermore, more up-to-date emissions 
information from EMFAC2021 indicates lower emissions of NOX 
and PM2.5 in the attainment year, indicating that the 
attainment modeling results derived using EMFAC2014 are conservative 
and that the 2023 attainment year design values are expected to be 
lower than those modeled in the Plan.
---------------------------------------------------------------------------

    \96\ 15 [micro]g/m\3\ SIP Revision, Appendix D, p. D-125. 
Transportation Conformity Budgets, Emissions Trading Mechanism, 
Table 21. These sensitivity simulations used the same modeling base 
case as the attainment demonstration for the 15 [micro]g/m\3\ SIP 
Revision.
    \97\ Spreadsheet ``EMFAC update effect on annual 1997 
PM2.5 NAAQS attainment demonstration,'' EPA Region IX, 
May 1, 2023.
---------------------------------------------------------------------------

    With respect to future year emissions projections in the 15 
[micro]g/m\3\ SIP Revision, we have reviewed the growth and control 
factors and are proposing to find them acceptable and thus conclude 
that the future baseline emissions projections in the SJV 
PM2.5 Plan, which reflect ongoing emissions reductions from 
existing (i.e., ``baseline'') control measures as discussed in Section 
IV.C.2.a, reflect appropriate calculation methods and the latest 
planning assumptions. Also, as a general matter, the EPA will approve a 
SIP submission that takes emissions reduction credit for a control 
measure only where the EPA has approved the measure as part of the SIP. 
Thus, for example, to take credit for the emissions reductions from 
newly adopted or amended District rules for stationary sources, the 
related rules must be approved by the EPA into the SIP. Table 2 of the 
EPA's ``Technical Support Document, San Joaquin Valley PM2.5 
Plan Revision for the 1997 Annual PM2.5 NAAQS,'' April 2023 
(``EPA's 1997 Annual PM2.5 TSD'') shows District rules with 
post-2013 compliance dates that are reflected in the future year 
baseline inventories, along with information on the EPA's approval of 
these rules, and shows that stationary source emissions reductions 
assumed by the SJV PM2.5 Plan for future years are supported 
by rules approved as part of the California SIP for the San Joaquin 
Valley. With respect to mobile sources, the EPA has taken action in 
recent years to approve CARB mobile source regulations into the state-
wide portion of the California SIP. We therefore find that the future 
year baseline projections in the SJV PM2.5 Plan are properly 
supported by SIP-approved stationary and mobile source measures.
    For these reasons, we are proposing to find that the 2013 base year 
emissions inventories in the SJV PM2.5 Plan for the 1997 
annual PM2.5 NAAQS continue to satisfy the requirements of 
CAA section 172(c)(3) and 40 CFR 51.1008 for purposes of both the 
Serious area and the CAA section 189(d) attainment plans. We are also 
proposing to find that the forecasted inventories in the Plan for the 
years 2017, 2018, 2019, 2020, 2023, and 2026 provide an adequate basis 
for the BACM, RFP, and the modeled attainment demonstration analyses in 
the SJV PM2.5 Plan.

B. PM2.5 Precursors

1. Statutory and Regulatory Requirements
    Under subpart 4 of part D, title I of the CAA and the 
PM2.5 SIP Requirements Rule, each state containing a 
PM2.5 nonattainment area must evaluate all PM2.5 
precursors for regulation unless, for any given PM2.5 
precursor, the state demonstrates to the Administrator's satisfaction 
that such precursor does not contribute significantly to 
PM2.5 levels that exceed the NAAQS in the nonattainment 
area.\98\ The provisions of subpart 4 do not define the term 
``precursor'' for purposes of PM2.5, nor do they explicitly 
require the control of any specifically identified PM precursor. The 
statutory definition of ``air pollutant,'' in CAA section 302(g), 
however, provides that the term ``includes any precursors to the 
formation of any air pollutant, to the extent the Administrator has 
identified such precursor or precursors for the particular purpose for 
which the term `air pollutant' is used.'' \99\ The EPA has identified 
NOX, SO2, VOC, and ammonia as precursors to the 
formation of PM2.5.\100\ Accordingly, the attainment plan 
requirements of subpart 4 apply to emissions of all four precursor 
pollutants and direct PM2.5 from all types of stationary, 
area, and mobile

[[Page 45286]]

sources, except as otherwise provided in the Act (e.g., in CAA section 
189(e)).
---------------------------------------------------------------------------

    \98\ 81 FR 58010, 58017-58020.
    \99\ CAA section 302(g).
    \100\ 81 FR 58010, 58015.
---------------------------------------------------------------------------

    Section 189(e) of the Act requires that the control requirements 
for major stationary sources of direct PM10 (which includes 
PM2.5) also apply to major stationary sources of 
PM10 precursors, except where the Administrator determines 
that such sources do not contribute significantly to PM10 
levels that exceed the standard in the area. Section 189(e) contains 
the only express exception to the control requirements under subpart 4 
(e.g., requirements for RACM, RACT, BACM, BACT, MSM, and nonattainment 
new source review (NSR)). Although section 189(e) explicitly addresses 
only major stationary sources, the EPA interprets the Act as 
authorizing it also to determine, under appropriate circumstances, that 
regulation of specific PM2.5 precursors from other source 
categories in a given nonattainment area is not necessary.\101\ For 
example, under the EPA's longstanding interpretation of the control 
requirements that apply to stationary and mobile sources of 
PM10 precursors in nonattainment areas under CAA section 
172(c)(1) and subpart 4,\102\ a state may demonstrate in a SIP 
submission that control of a certain precursor pollutant is not 
necessary because it does not contribute significantly to ambient 
PM10 levels in the nonattainment area and is not needed for 
attainment.\103\
---------------------------------------------------------------------------

    \101\ Id. at 58018-58019.
    \102\ General Preamble, 13539-13542.
    \103\ Courts have upheld this approach to the requirements of 
subpart 4 for PM10. See, e.g., Assoc. of Irritated 
Residents v. EPA, et al., 423 F.3d 989 (9th Cir. 2005).
---------------------------------------------------------------------------

    Under the PM2.5 SIP Requirements Rule, a state may elect 
to submit to the EPA a ``comprehensive precursor demonstration'' for a 
specific nonattainment area to show that emissions of a particular 
precursor from all existing sources located in the nonattainment area 
do not contribute significantly to PM2.5 levels that exceed 
the standard in the area.\104\ If the EPA determines that the 
contribution of the precursor to PM2.5 levels in the area is 
not significant and approves the demonstration, the state is not 
required to control emissions of the relevant precursor from existing 
sources in the attainment plan.\105\
---------------------------------------------------------------------------

    \104\ 40 CFR 51.1006(a)(1).
    \105\ Id. A state may also perform a separate, ``NNSR precursor 
demonstration'' to evaluate the sensitivity of PM2.5 
levels in the nonattainment area to an increase in emissions of a 
particular precursor and determine if new major stationary sources 
and major modifications of a precursor would contribute 
significantly to PM2.5 levels that exceed the standard in 
the nonattainment area. 40 CFR 51.1006(a)(3).
---------------------------------------------------------------------------

    In addition, in May 2019, the EPA issued the ``PM2.5 
Precursor Demonstration Guidance'' (``PM2.5 Precursor 
Guidance''),\106\ which provides recommendations to states for 
analyzing nonattainment area PM2.5 emissions and developing 
such optional precursor demonstrations, consistent with the 
PM2.5 SIP Requirements Rule. The EPA developed recommended 
contribution thresholds to help assess whether a precursor 
significantly contributes to PM2.5 levels above the NAAQS. 
The thresholds are based on the size of PM2.5 concentration 
increases that are statistically indistinguishable from the inherent 
variability in the measured atmospheric concentrations.\107\ If the 
chemical component of PM2.5 ambient concentrations 
corresponding to emissions of a precursor (e.g., the concentration of 
sulfate, which corresponds to SO2 emissions) is below the 
threshold, that is evidence that the precursor does not significantly 
contribute. If the precursor is above the threshold in this 
concentration-based test, the State can use a sensitivity-based test, 
in which the modeled sensitivity or response of ambient 
PM2.5 concentrations to changes in emissions of the 
precursor is estimated and then compared to the threshold. The EPA's 
recommended annual average contribution threshold for purposes of the 
2012 annual PM2.5 NAAQS is 0.2 [micro]g/m\3\.\108\ The 
PM2.5 Precursor Guidance explains that this threshold 
represents a percentage of the 2012 annual NAAQS and that ``[d]ifferent 
thresholds may be applicable to other levels and/or forms of the NAAQS 
(either past or future).'' \109\ In addition to comparing the 
concentration or modeled response to the threshold, the State can 
consider other information in assessing whether the precursor 
significantly contributes.
---------------------------------------------------------------------------

    \106\ ``PM2.5 Precursor Demonstration Guidance,'' 
EPA-454/R-19-004, May 2019, including memorandum dated May 30, 2019, 
from Scott Mathias, Acting Director, Air Quality Policy Division and 
Richard Wayland, Director, Air Quality Assessment Division, Office 
of Air Quality Planning and Standards (OAQPS), EPA to Regional Air 
Division Directors, Regions 1-10, EPA. The PM2.5 
Precursor Guidance builds upon the draft version of the guidance, 
released on November 17, 2016 (``Draft PM2.5 Precursor 
Guidance''), which CARB referenced in developing its precursor 
demonstration in the SJV PM2.5 Plan. ``PM2.5 
Precursor Demonstration Guidance, Draft for Public Review and 
Comments,'' EPA-454/P-16-001, November 17, 2016, including 
memorandum dated November 17, 2016, from Stephen D. Page, Director, 
OAQPS, EPA to Regional Air Division Directors, Regions 1-10, EPA.
    \107\ PM2.5 Precursor Guidance, p. 15.
    \108\ Id. at 17.
    \109\ Id. at fn. 20.
---------------------------------------------------------------------------

    As explained in the PM2.5 Precursor Guidance, and 
consistent with the PM2.5 SIP Requirements Rule (40 CFR 
51.1010(a)(2)(ii), 51.1006(a)(1)(ii)), the EPA may require an air 
agency to identify and evaluate potential control measures for a 
precursor to determine the potential emissions reductions achievable, 
in support of a precursor demonstration that relies on a sensitivity 
analysis.\110\ The guidance states that such evaluation is particularly 
important for an area in which the PM2.5 response to a 30 
percent reduction in precursor emissions is close to the contribution 
threshold. In the case of a nonattainment area classified as Serious, 
this analysis would include identification and evaluation of measures 
that would constitute BACM/BACT level control for such pollutant.\111\ 
Consistent with these regulations, the EPA requested that the State 
identify and evaluate potential control measures for ammonia to 
determine the potential emissions reductions achievable for purposes of 
the 1997 annual PM2.5 NAAQS.
---------------------------------------------------------------------------

    \110\ Id. at 31.
    \111\ Id.
---------------------------------------------------------------------------

    We are evaluating the SJV PM2.5 Plan in accordance with 
the presumption embodied within subpart 4, that states must address all 
PM2.5 precursors in the evaluation of potential control 
measures unless the state adequately demonstrates that emissions of a 
particular precursor or precursors do not contribute significantly to 
ambient PM2.5 levels that exceed the PM2.5 NAAQS 
in the nonattainment area. In reviewing any determination by a state to 
exclude a PM2.5 precursor from the required evaluation of 
potential control measures, we consider both the magnitude of the 
precursor's contribution to ambient PM2.5 concentrations in 
the nonattainment area and, where the state has conducted sensitivity-
based analyses, the sensitivity of ambient PM2.5 
concentrations in the area to reductions in emissions of that precursor 
in accordance with the PM2.5 Precursor Guidance.
2. Summary of the State's Submission
    The State presents some results and conclusions from its 
PM2.5 precursor sensitivity analysis in Chapter 5 
(``Demonstration of Federal Requirements for 1997 PM2.5 
Standards''), Section 5.3.1 (``Summary of Modeling Results'') of the 15 
[micro]g/m\3\ SIP Revision, and presents the full

[[Page 45287]]

precursor demonstration in Appendix G (``Precursor Demonstration'') of 
the 2018 PM2.5 Plan.\112\ CARB presents additional modeling 
results in Appendix K (``Modeling Attainment Demonstration'') of the 15 
[micro]g/m\3\ SIP Revision. CARB also provided clarifying information 
on its precursor assessment, including an Attachment A to its letter 
transmitting the 2018 PM2.5 Plan to the EPA \113\ and 
further clarifications in five email transmittals.\114\ CARB's December 
2018 Staff Report and August 2021 Staff Report contain additional 
discussion of the role of ammonia in the formation of ammonium nitrate 
and the role of VOC in the formation of ammonium nitrate and secondary 
organic aerosol.\115\ Lastly, on March 30, 2023, CARB transmitted to 
the EPA a technical supplement titled ``Ammonia: Supplemental 
Information for EPA in Support of 15 [micro]g/m\3\ Annual 
PM2.5 Standard, March 2023'' (``March 2023 Ammonia 
Supplement'') in which CARB and the District ``clarify CARB's 
assessment of ammonia as a precursor to fine particulate matter 
(PM2.5) for the 15 [micro]g/m\3\ annual standard by 
summarizing information previously submitted to EPA and providing new 
detailed control measure analysis'' \116\ to assess potential ammonia 
emissions reductions achievable in the San Joaquin Valley through the 
implementation of best available controls.
---------------------------------------------------------------------------

    \112\ Appendix G was not changed relative to the 2018 
PM2.5 Plan for the 15 [micro]g/m\3\ SIP Revision.
    \113\ Letter dated May 9, 2019, from Richard Corey, Executive 
Officer, CARB, to Michael Stoker, Regional Administrator, EPA Region 
9, Attachment A (``Clarifying information for the San Joaquin Valley 
2018 Plan regarding model sensitivity related to ammonia and ammonia 
controls'').
    \114\ Email dated June 20, 2019, from Jeremy Avise, CARB, to 
Scott Bohning, EPA Region IX, Subject: ``RE: SJV model disbenefit 
from SOX reduction,'' with attachment (``CARB's June 2019 
Precursor Clarification''); email dated September 19, 2019, from 
Jeremy Avise, CARB, to Scott Bohning, EPA Region IX, Subject: ``FW: 
SJV species responses,'' with attachments (``CARB's September 2019 
Precursor Clarification''); email dated October 18, 2019, from Laura 
Carr, CARB, to Scott Bohning, Jeanhee Hong, and Rory Mays, EPA 
Region IX, Subject: ``Clarifying information on ammonia,'' with 
attachment ``Clarifying Information on Ammonia'' (``CARB's October 
2019 Precursor Clarification''); email dated April 19, 2021, from 
Laura Carr, CARB, to Rory Mays, EPA Region IX, Subject: ``Ammonia 
update,'' with attachment ``Update on Ammonia in the San Joaquin 
Valley'' (``CARB's April 19, 2021 Precursor Clarification''); and 
email dated April 26, 2021, from Laura Carr, CARB, to Scott Bohning, 
EPA Region IX, Subject: ``RE: Ammonia update,'' with attachment 
``Ammonia in San Joaquin Valley'' (``CARB's April 26, 2021 Precursor 
Clarification'').
    \115\ December 2018 Staff Report, Appendix C, pp. 9-16, and 
August 2021 Staff Report, pp. 8-9 and Attachment 1. Attachment 1 is 
identical to the attachment to CARB's April 19, 2021 Precursor 
Clarification.
    \116\ Letter dated March 29, 2023, from Steven S. Cliff, 
Executive Officer, CARB, to Martha Guzman, Regional Administrator, 
EPA Region 9, with enclosures.
---------------------------------------------------------------------------

    The SJV PM2.5 Plan provides both concentration-based and 
sensitivity-based analyses of precursor contributions to ambient 
PM2.5 concentrations in the San Joaquin Valley. For the 
concentration-based analysis, CARB assessed the 2015 annual average 
concentration of each precursor in ambient PM2.5 at 
Bakersfield, for which the necessary speciated PM2.5 data 
are available and where the highest PM2.5 design values have 
been recorded in most years. CARB concludes that the 2015 annual 
average contributions of ammonia, SOX, and VOC are 5.2 
[micro]g/m\3\, 1.6 [micro]g/m\3\, and 6.2 [micro]g/m\3\, respectively. 
Given that these levels are above the EPA's recommended contribution 
threshold, the State proceeded with a sensitivity-based analysis.
    CARB's sensitivity-based analysis used the same Community 
Multiscale Air Quality (CMAQ) modeling platform as that used for the 
Plan's attainment demonstration, described in Section IV.D. of this 
proposal. The State modeled the sensitivity of ambient PM2.5 
concentration in the San Joaquin Valley to 30 percent and 70 percent 
reductions in anthropogenic emissions of each precursor pollutant for 
modeled years 2013, 2020, and 2024. The year 2013 is the 2018 
PM2.5 Plan's base year; 2020 is the modeled attainment year 
for the 1997 24-hour PM2.5 NAAQS and former modeled 
attainment year for the 1997 annual PM2.5 NAAQS; and 2024 is 
the modeled attainment year for the 2006 24-hour PM2.5 
NAAQS. For the 1997 annual PM2.5 NAAQS, the revised modeled 
attainment year is 2023, but the State did not conduct precursor 
sensitivity modeling for that additional year. Instead, the State 
assumed that 2023 and 2024 would have very similar results; \117\ and 
results for 2024 were used as a proxy for those in 2023.
---------------------------------------------------------------------------

    \117\ 15 [micro]g/m\3\ SIP Revision, Chapter 5, p. 5-8, and 
March 2023 Ammonia Supplement, fn. 35.
---------------------------------------------------------------------------

    In Appendix G of the 2018 PM2.5 Plan, the State compared 
its sensitivity modeling results to the recommended annual average 
contribution threshold of 0.2 [micro]g/m\3\ in the PM2.5 
Precursor Guidance. As discussed in Section IV.B.1, the 0.2 [micro]g/
m\3\ contribution threshold was derived based on the level of the 2012 
annual PM2.5 NAAQS (i.e., 12.0 [micro]g/m\3\). In the March 
2023 Ammonia Supplement, the State explains that adjusting the 
contribution threshold to the level of the 1997 annual PM2.5 
NAAQS (i.e., 15.0 [micro]g/m\3\) results in a contribution threshold of 
0.25 [micro]g/m\3\ and presents an updated evaluation of the modeled 
concentration-based and sensitivity-based analyses for ammonia using 
the 0.25 [micro]g/m\3\ threshold.\118\
---------------------------------------------------------------------------

    \118\ The State did not provide an updated analysis using the 
0.25 [micro]g/m\3\ threshold for SOX or VOC.
---------------------------------------------------------------------------

    In collaboration with the District, the State supplemented the 
sensitivity analysis, particularly for ammonia, with consideration of 
additional information such as emissions trends, the appropriateness of 
future year versus base year sensitivity, the severity of 
nonattainment, and a detailed controls analysis.\119\ These factors 
were identified in the then-available Draft PM2.5 Precursor 
Guidance, as well as in the final PM2.5 Precursor Guidance, 
as factors that may be relevant to a sensitivity-based contribution 
analysis.\120\
---------------------------------------------------------------------------

    \119\ 2018 PM2.5 Plan, Appendix G, pp. 8-10, and 
March 2023 Ammonia Supplement, pp. 13-96.
    \120\ PM2.5 Precursor Guidance, pp. 18-19 
(consideration of additional information), p. 31 (available emission 
controls), and pp. 35-36 (appropriateness of future year versus base 
year sensitivity).
---------------------------------------------------------------------------

    Taken together, these analyses led CARB to conclude that 
NOX remains a plan precursor but that ammonia, 
SOX, and VOC do not contribute significantly to ambient 
PM2.5 levels that exceed the PM2.5 NAAQS in the 
San Joaquin Valley. We summarize the State's analysis and conclusions 
below. For a more detailed summary of the precursor demonstration in 
the Plan, please refer to the EPA's ``Technical Support Document, EPA 
Evaluation of PM2.5 Precursor Demonstration, San Joaquin 
Valley PM2.5 Plan for the 2006 PM2.5 NAAQS,'' 
February 2020 (``EPA's February 2020 Precursor TSD'').
a. Ammonia
    For the ammonia analysis presented in Appendix G of the 2018 
PM2.5 Plan, the State compared the annual precursor 
contributions to 0.2 [micro]g/m\3\, the contribution threshold 
recommended for the 2012 annual PM2.5 NAAQS in the 
PM2.5 Precursor Guidance. The State supplemented this 
analysis in the March 2023 Ammonia Supplement by comparing the annual 
ammonia contributions to the 0.25 [micro]g/m\3\ threshold it derived 
for the 1997 annual PM2.5 NAAQS. For a modeled 30 percent 
ammonia emissions reduction, the ambient PM2.5 responses in 
2013 ranged from 0.20 to 0.72 [micro]g/m\3\ across 15 monitoring sites, 
with all of the sites at or above the 0.2 [micro]g/m\3\ contribution 
threshold and all but two of the sites above the 0.25 [micro]g/m\3\ 
contribution threshold. PM2.5 responses in 2020 ranged from 
0.12 to 0.42 [micro]g/m\3\, with nine sites above the 0.2 [micro]g/m\3\ 
contribution threshold and four sites

[[Page 45288]]

above the 0.25 [micro]g/m\3\ contribution threshold. Responses in 2024 
ranged from 0.08 to 0.26 [micro]g/m\3\, with two sites above the 0.2 
[micro]g/m\3\ contribution threshold and one site above the 0.25 
[micro]g/m\3\ contribution threshold. For a modeled 70 percent ammonia 
emissions reduction, the ambient PM2.5 responses were above 
both thresholds at all 15 sites for all three modeled years.
    The State based its ammonia precursor determination on the 
sensitivity analysis for the future years, using a 30 percent ammonia 
emissions reduction. This was supported by its assessment of research 
studies and the Plan's projected emissions reductions, and its 
assessment of available emissions controls. As explained in the 
PM2.5 Precursor Guidance, precursor responses may be above 
the recommended contribution threshold and yet not contribute 
significantly to levels that exceed the standard in the area.\121\ 
Therefore, the State considered additional information to examine 
whether the identified PM2.5 responses constituted a 
significant contribution to ambient PM2.5 in the San Joaquin 
Valley. The additional information included emissions trends, support 
for the State's reliance on modeling results for a 30 percent ammonia 
emissions reduction, as well as conclusions from research studies.
---------------------------------------------------------------------------

    \121\ PM2.5 Precursor Guidance, p. 18.
---------------------------------------------------------------------------

    The State estimates that NOX emissions in the San 
Joaquin Valley are projected to decrease by 53 percent from 2013 to 
2024, while ammonia emissions are projected to remain relatively flat, 
thereby increasing the relative abundance of ammonia.\122\ Based on the 
Plan's emission reduction projections combined with the research study 
conclusions, the State relies on the modeled responses for the 2024 
future year, rather than the 2013 base year, stating that the future 
year NOX emissions are more representative of San Joaquin 
Valley emissions conditions.\123\ The State references the Draft 
PM2.5 Precursor Guidance, which notes that it may be 
appropriate to model future conditions that are more representative of 
current atmospheric conditions and those conditions expected closer to 
the attainment date.\124\ The State concludes that this in fact applies 
to the San Joaquin Valley.\125\
---------------------------------------------------------------------------

    \122\ March 2023 Ammonia Supplement, pp. 14-15.
    \123\ Id. at 15 and 17.
    \124\ Id. at 13 (referencing Draft PM2.5 Precursor 
Guidance, p. 33). See also PM2.5 Precursor Guidance, p. 
35.
    \125\ Id. at 15.
---------------------------------------------------------------------------

    The State also describes previous research studies that support its 
conclusion that ammonium nitrate PM2.5 formation in the San 
Joaquin Valley is NOX-limited rather than ammonia-
limited.\126\ For example, based on aircraft-borne measurements during 
the 2013 DISCOVER-AQ campaign,\127\ the State concluded that ammonium 
nitrate formation is NOX-limited based on the large amount 
of ``excess ammonia,'' which is defined as the amount of measured 
ammonia left over if all the nitrate and sulfate present were to 
combine with available ammonia to form particulate.\128\ CARB's 
December 2018 Staff Report describes these conclusions in more detail 
and lists results from multiple other recent studies with similar 
conclusions.\129\ The studies suggest a very low ambient sensitivity to 
ammonia, based on measured excess ammonia relative to NOX, 
the abundance of particulate nitrate relative to gaseous 
NOX, and the large abundance of ammonia relative to nitric 
acid. The studies all conclude that there is a large amount of ammonia 
left over after reacting with NOX, so that ammonia emission 
reductions would be expected mainly to reduce the amount of ammonia 
excess, rather than to reduce the particulate amonium nitrate.
---------------------------------------------------------------------------

    \126\ 2018 PM2.5 Plan, Appendix G, pp. 9-10; December 
2018 Staff Report, Appendix C, pp. 12-15; and Attachment A to CARB's 
May 9, 2019, submittal letter.
    \127\ Deriving Information on Surface conditions from COlumn and 
VERtically Resolved Observations Relevant to Air Quality,'' https://www.nasa.gov/mission_pages/discover-aq/index.html.
    \128\ 2018 PM2.5 Plan, Appendix G, Figure 2.
    \129\ December 2018 Staff Report, Appendix C, p. 12; and 
Attachment A to CARB's May 9, 2019 submittal letter. These studies 
are also discussed in the EPA's February 2020 Precursor TSD.
---------------------------------------------------------------------------

    CARB also describes the results of two studies indicating that 
ammonia concentrations may be underestimated in modeling of the 
DISCOVER-AQ early 2013 study period, which would result in the response 
to ammonia reductions being overpredicted.\130\ CARB conducted its own 
analysis comparing 2017 satellite observations with CMAQ model 
predictions and found that modeled ammonia concentrations were half of 
the magnitude of the satellite observations at some locations and that 
the modeled valley-wide average was approximately 25 percent less than 
observed. Taken together, CARB concludes that these studies provide 
evidence that PM2.5 would respond only weakly to ammonia 
emissions reductions.
---------------------------------------------------------------------------

    \130\ CARB's April 19, 2021 Precursor Clarification; CARB's 
April 26, 2021 Precursor Clarification. The modeling used for the 
attainment demonstration has enough excess ammonia to correctly 
predict ammonium nitrate and ammonium sulfate PM2.5 
concentrations, but likely less of an excess than indicated from 
ambient measurements of ammonia itself.
---------------------------------------------------------------------------

    Finally, the State and District provided additional information, 
both in the SJV PM2.5 Plan and in the March 2023 Ammonia 
Supplement, to support its conclusion that 30 percent is a reasonable 
upper bound on the ammonia reductions that are practically available, 
and as a basis for its reliance on the modeling results for a 30 
percent ammonia emissions reduction. This information includes a review 
of ammonia emission reductions achieved nationwide from 2011 to 2017 as 
summarized in the EPA's PM2.5 Precursor Guidance,\131\ an 
evaluation of the main ammonia source categories in the San Joaquin 
Valley,\132\ a summary of existing control measures in the San Joaquin 
Valley that affect ammonia from these sources,\133\ a review of 
existing control measures implemented by other air districts,\134\ and 
an evaluation of additional mitigation options for ammonia sources in 
the Valley.\135\ We briefly summarize the State's analyses and 
conclusions for relying on a 30 percent upper bound in the following 
paragraphs. For a more detailed summary of the State's ammonia control 
measure analysis, please refer to the EPA's 1997 annual 
PM2.5 TSD.\136\
---------------------------------------------------------------------------

    \131\ March 2023 Ammonia Supplement, p. 11. See also 
PM2.5 Precursor Guidance, Section 4.1.1.
    \132\ March 2023 Ammonia Supplement, pp. 20-25.
    \133\ Id. at 25, and 2018 PM2.5 Plan, Appendix C, 
Section C-25.
    \134\ March 2023 Ammonia Supplement, pp. 26-27, and 2018 
PM2.5 Plan, Appendix C, Section C-25.
    \135\ March 2023 Ammonia Supplement, pp. 28-96.
    \136\ EPA, Technical Support Document, ``San Joaquin Valley 
PM2.5 Plan Revision for the 1997 annual PM2.5 
NAAQS,'' April 2023.
---------------------------------------------------------------------------

    First, CARB and the District reason that trends in ammonia 
emissions provided in the PM2.5 Precursor Guidance, which 
show a national increase of 0.8 percent in ammonia emissions between 
2011-2017, are indicative of a lack of controls on ammonia sources 
nationwide.\137\ The March 2023 Ammonia Supplement includes a 
comparison of the guidance trends in ammonia with trends in 
NOX and SO2 over the same period, which decreased 
by 63.6 percent and 31.8 percent, respectively, which CARB and the 
District attribute to control measures to reduce emissions of these 
pollutants. The State acknowledges that new controls for ammonia are 
being researched but states that the recent emissions trends suggest 
that a 30 percent reduction in ammonia is a conservative upper bound on 
what is achievable. To further support that statement, the District and 
State

[[Page 45289]]

collaborated on an evaluation of potential control measures to reduce 
ammonia emissions in the San Joaquin Valley for the March 2023 Ammonia 
Supplement.
---------------------------------------------------------------------------

    \137\ March 2023 Ammonia Supplement, p. 11.
---------------------------------------------------------------------------

    The first step in the control measure evaluation was to 
characterize the key sources of ammonia in the Valley. The three main 
sources of ammonia emissions identified in the Plan are: (1) confined 
animal facilities (CAFs); (2) agricultural fertilizers; and (3) 
composting operations, which together account for 94 percent of the 
Valley's ammonia emissions.\138\ CAFs are subject to District Rule 4570 
(``Confined Animal Facilities''), and composting operations are subject 
to District Rule 4565 (``Biosolids, Animal Manure, and Poultry Litter 
Operations'') and District Rule 4566 (``Organic Material Composting 
Operations''). Although these District rules explicitly apply only to 
VOC emissions from these sources, the State concludes that these rules 
have also resulted in significant reductions in ammonia emissions.\139\ 
Appendix C of the 2018 PM2.5 Plan cites a number of 
scientific studies that address the correlation between VOC and ammonia 
emissions from these emission sources.\140\ Given that CAFs and 
agricultural fertilizers account for 92 percent of the ammonia 
emissions inventory in the San Joaquin Valley,\141\ and that ammonia 
emissions from composting operations account for only 2 percent of the 
ammonia emissions inventory and have already been reduced through 
District Rules 4565 and 4566, the ammonia control measure evaluation 
focused primarily on potential controls for CAFs and agricultural 
fertilizers.
---------------------------------------------------------------------------

    \138\ Id. at 20.
    \139\ Id. at 26 and 96.
    \140\ 2018 PM2.5 Plan, Appendix C, Section C-25.
    \141\ March 2023 Ammonia Supplement, Figure 4.
---------------------------------------------------------------------------

    For CAFs, the District provides an inventory of the types of 
facilities operating in the Valley subject to Rule 4570 and the 
corresponding ammonia emissions from each facility type.\142\ For dairy 
cattle, which accounts for an estimated 67.2 percent of ammonia 
emissions from CAFs, the District assessed how the different CAF 
operations contribute to the overall ammonia inventory. For example, 
the District estimates that 56.6 percent of dairy cattle ammonia 
emissions are from housing dairy cattle in corrals/pens, 11.1 percent 
of emissions are from lagoons and storage ponds, and 12.0 percent of 
emissions occur during land application of liquid manure.\143\
---------------------------------------------------------------------------

    \142\ Id. at Figure 5 and Table 7.
    \143\ Id. at Figure 7.
---------------------------------------------------------------------------

    Next, the District discusses ammonia mitigation measures that are 
already being implemented in the Valley. The District discusses in 
detail in Appendix C of the 2018 PM2.5 Plan how Rule 4570 is 
structured (e.g., to address varying types of CAFs); the five main CAF 
operations/emission sources: feeding, housing (including distinctions 
for housing configurations), solid waste, liquid waste, and land 
application of manure; the control menu requirements for each of those 
five operations; and research papers that estimate ammonia emission 
reductions from some of the measures.\144\ The District explains that 
some of the measures in Rule 4570 are required to be implemented but 
that the rule also requires additional measures to be selected from a 
menu of options.\145\ The menu-based approach is intended to allow 
facilities flexibility to select measures that are the most practical 
and effective for their design and operation given the District's 
findings of variability within the industry.\146\
---------------------------------------------------------------------------

    \144\ 2018 PM2.5 Plan, Appendix C, pp. C-312 to C-
323.
    \145\ Id. and March 2023 Ammonia Supplement, pp. 25-26.
    \146\ Id.
---------------------------------------------------------------------------

    As a first step in assessing whether there are additional feasible 
control measures for CAFs that are not yet being implemented in the 
Valley, the District evaluated other district CAF rules with 
requirements comparable to those in Rule 4570.\147\ The District 
reviewed CAF rules implemented by the South Coast Air Quality 
Management District (AQMD), Bay Area AQMD, Ventura County Air Pollution 
Control District (APCD), Sacramento Metropolitan AQMD, Imperial County 
APCD, and the State of Idaho.\148\ The District also points to 
comparisons between Rule 4570 and two additional sets of requirements 
imposed by Butte County APCD and Yakima Regional Clean Air Agency, as 
conducted for the ``2016 Plan for the 2008 8-hour Ozone Standard.'' 
\149\ Based on comparisons between specific requirements, the State 
concludes that Rule 4570 is more stringent than other district rules 
and no additional requirements are currently being implemented in other 
areas.\150\
---------------------------------------------------------------------------

    \147\ March 2023 Ammonia Supplement, pp. 26-27.
    \148\ 2018 PM2.5 Plan, Appendix C, Section C-25.
    \149\ March 2023 Ammonia Supplement, p. 27.
    \150\ Id.
---------------------------------------------------------------------------

    The second step in the control measure analysis was to review 
scientific research studies on mitigating ammonia emissions from CAFs. 
In Appendix A of the March 2023 Ammonia Supplement, the District 
provides a list of research studies and potential ammonia control 
measures it considered. For each of the 46 mitigation measures 
identified in the literature, the State provides a narrative detailing 
its evaluation of the feasibility of implementation of the measure in 
the San Joaquin Valley.\151\ The State's analysis covers a broad range 
of CAF activities, including animal feeding and housing, and the 
storage, handling, and land application of manure. The analysis also 
addresses a number of other mitigation options, such as pasture and 
range land management, land use changes, and planting a tree shelter 
belt near CAFs.\152\ Based on these evaluations, the State identified 
three measures that could provide further reductions in ammonia 
emissions in the San Joaquin Valley. These measures include 1) reducing 
the crude protein content in feed for beef finishing cattle, 2) 
incorporating solid manure into the soil within 24-hours, and 3) adding 
acidifying amendments to poultry litter and manure.\153\ Based on 
control efficiencies cited in the literature, the District estimates 
that the total emissions reductions achievable from these measures is 
6.6 tons per day (tpd), which is approximately two percent of the 2023 
inventory. For those measures it found to be infeasible in the San 
Joaquin Valley, the District includes a narrative explaining its 
conclusion.
---------------------------------------------------------------------------

    \151\ Id. at 28-85.
    \152\ Id. at 86-88.
    \153\ Id. at 88-89.
---------------------------------------------------------------------------

    Regarding fertilizer application, the State provides an estimate of 
111.2 tpd of ammonia emissions in 2023.\154\ In the 2018 
PM2.5 Plan, the District describes key research assessing 
nitrogen in California, as well as regulations adopted by the 
California Water Resources Control Board, including orders adopted by 
the Central Valley Regional Water Quality Control Board (e.g., a 
Nutrient Management Plan), the Irrigated Lands Regulatory Program 
(e.g., a Nitrogen Management Plan), and other individual orders on 
agricultural operations not subject to those programs.\155\ These 
orders subject agricultural operators, including dairies, bovine 
feedlots, poultry operations, and crop farmers to ``waste discharge 
requirements that protect both surface water and groundwater.'' \156\
---------------------------------------------------------------------------

    \154\ Id. at 89.
    \155\ 2018 PM2.5 Plan, Appendix C, pp. C-339 to C-
343.
    \156\ Id. at C-341.
---------------------------------------------------------------------------

    In the March 2023 Ammonia Supplement, the State supplemented its 
prior analysis by explaining how various state agencies are engaged in 
fertilizer use and application and discussing its efforts to identify 
any

[[Page 45290]]

existing rules or regulations in the nation controlling ammonia 
emissions from this source category.\157\ CARB states that it has not 
identified any measures that are being implemented to reduce ammonia 
and thus, again turns to scientific research studies on ammonia 
mitigation measures to assess the potential emissions reductions that 
could be achieved from fertilizer application. The measures identified 
in the literature for reducing ammonia emissions from fertilizer 
application include optimizing fertilizer use, adding a urease 
inhibitor, mixing and injecting fertilizer into the soil quickly, and 
applying fertilizer during optimal weather conditions. Based on its 
review, the State finds that several of the strategies identified in 
the literature are consistent with strategies recommended by the 
California Department of Food and Agriculture Fertilizer Research and 
Education Program as part of its Irrigation and Nitrogen Management 
training program, which includes overviews of the ``4 R's'' of nitrogen 
management: ``Right source'' of nitrogen at the ``right rate,'' ``right 
time,'' and ``right place.'' \158\ However, the State concludes that 
more research is needed to explore the feasibility and effectiveness of 
requiring some of the identified strategies in California, due in part 
to the warmer and dryer climate conditions in the San Joaquin Valley 
compared to, for example, the European climate in which many of the 
research studies were conducted, and due to the need to explore any 
potential adverse consequences. Thus, the State concludes that 
additional reductions in ammonia from fertilizer application are not 
feasible at this time.\159\
---------------------------------------------------------------------------

    \157\ March 2023 Ammonia Supplement, pp. 89-92.
    \158\ Id. at 92.
    \159\ Id. at 96.
---------------------------------------------------------------------------

    For composting operations and other ammonia sources, the District 
notes that it currently regulates ammonia emissions from composting 
though Rules 4565 and 4566 and states that these rules have reduced 
ammonia emissions by 44 percent. Given that composting amounts to only 
two percent of the total ammonia emissions, the District did not 
provide any further evaluation for this source category. For the 
remaining ammonia sources in the Valley covered under ``other'' source 
category, which amounts to 6 percent of the total inventory, the 
District notes that ammonia emissions are primarily from mobile sources 
and fuel combustion, which it asserts are also already controlled. The 
District concludes that no additional reductions are available from 
composting operations or other ammonia sources.\160\
---------------------------------------------------------------------------

    \160\ Id.
---------------------------------------------------------------------------

    Taken together, the State estimates that ammonia emissions could be 
reduced by 6.6 tpd in the San Joaquin Valley through three additional 
mitigation measures for CAFs, which would amount to a total ammonia 
reduction of 2 percent. Based on this analysis, the State concludes 
that ammonia control measures achieving even the low end of the modeled 
range (i.e., 30 percent) are not feasible for implementation in the San 
Joaquin Valley, and that it is therefore reasonable to treat a 30 
percent ammonia reduction as a conservative upper bound on the 
reductions that are achievable, and to base the analysis in the 
precursor demonstration on the model response to a 30 percent 
reduction.
    In summary, the State's sensitivity analysis presents a range of 
PM2.5 responses to ammonia emissions reductions in multiple 
modeled years. The State describes in the Plan its bases for finding 
that the 2024 future year sensitivity results better represent 
conditions in the San Joaquin Valley than the 2013 base year, and for 
finding a 30 percent ammonia reduction to be a reasonable upper bound 
on the ammonia emissions reductions available for assessing the ammonia 
contribution. Based on these analyses of the modeled response to 
ammonia reductions below the threshold, additional ambient evidence, 
and the amount of reductions available from controls, the State 
concludes that ammonia does not contribute significantly to ambient 
PM2.5 levels above the 1997 annual PM2.5 NAAQS in 
the San Joaquin Valley.
b. SOX
    For SOX, the State compares the annual precursor 
contributions to the contribution threshold of 0.2 [micro]g/m\3\ 
recommended for the 2012 annual PM2.5 NAAQS in the 
PM2.5 Precursor Guidance. For modeled SOX 
emissions reductions of 30 percent and 70 percent, the ambient 
PM2.5 responses in 2013 ranged from -0.05 [micro]g/m\3\ to 
0.15 [micro]g/m\3\ across 15 monitoring sites, which all fall below the 
0.20 [micro]g/m\3\ contribution threshold.\161\ The response was below 
zero in select cases, indicating an increase, rather than a decrease, 
in ambient PM2.5 in response to SOX emissions 
reductions (i.e., a disbenefit). For 2020, the responses to 30 percent 
and 70 percent emissions reductions ranged from -0.01 [micro]g/m\3\ to 
0.16 [micro]g/m\3\ while for 2024, the responses ranged from 0.01 
[micro]g/m\3\ to 0.08 [micro]g/m\3\; these are also all below the 0.2 
[micro]g/m\3\ contribution threshold.\162\
---------------------------------------------------------------------------

    \161\ 2018 PM2.5 Plan, Appendix G, tables 8 and 9.
    \162\ CARB's September 2019 Precursor Clarification, 2020 
analysis tables 7 and 8, and 2024 analysis tables 7 and 8.
---------------------------------------------------------------------------

    To explain the SOX emissions reduction disbenefit that 
is observed in some cases, CARB refers to the non-linearity of 
inorganic aerosol thermodynamics, as described in a study by West et 
al.\163\ The paper discusses how, under certain conditions, reducing 
SOX could free ammonia to combine with nitrate, increasing 
overall PM2.5 mass. To investigate this issue further, CARB 
conducted simulations with the ISORROPIA inorganic aerosol 
thermodynamic equilibrium model used within the CMAQ model and provided 
clarifications to the EPA.\164\ In essence, CARB states that for some 
conditions typical of San Joaquin Valley, ISORROPIA switches to a 
different chemical regime in which the disbenefit occurs. CARB states 
that it is not known how well this model behavior reflects the actual 
atmosphere, but CARB accepts the results because it is a well-known and 
widely used chemical model.
---------------------------------------------------------------------------

    \163\ 15 [micro]g/m\3\ SIP Revision, Appendix K, Section 5.7 
(``PM2.5 Precursor Sensitivity Analysis''); and West, 
J.J., Ansari, A.S., Pandis, S.N., 1999, Marginal PM2.5: 
Nonlinear aerosol mass response to sulfate reductions in the eastern 
United States, Journal of the Air & Waste Management Association, 
49, 1415-1424. https://doi.org/10.1080/10473289.1999.10463973.
    \164\ CARB's June 2019 Precursor Clarification.
---------------------------------------------------------------------------

    The State also provides an emissions trend chart that shows that 
SOX emissions are approximately constant at 8 tpd from 2013 
through 2024. Given that the relative levels of estimated 
SOX and ammonia emissions over the timeframe remain similar, 
the State concludes that 2013 sensitivities are also representative of 
future years.\165\
---------------------------------------------------------------------------

    \165\ 2018 PM2.5 Plan, Appendix G, p. 15. The State 
includes modeling of 30 percent and 70 percent reductions of 
SOX for 2013 only, finding that the sensitivity of 
ambient PM2.5 to such changes were below the EPA's 
recommended threshold, and that the 2020 and 2024 results would 
differ little from 2013 due to the similarity of emissions 
conditions over time. Appendix G, p. 17. CARB's September 2019 
Precursor Clarification provides the 2020 and 2024 sensitivity 
results, which are indeed very close to those for 2013.
---------------------------------------------------------------------------

    Based on the small modeled response of ambient PM2.5 to 
SOX emissions reductions, the constant SOX 
emissions over time, and its scientific understanding of sulfate 
interactions with other molecules in the air, the State concludes that 
SOX does not contribute significantly to ambient 
PM2.5 levels that exceed the 1997 annual

[[Page 45291]]

PM2.5 NAAQS in the San Joaquin Valley.
c. VOC
    For VOC, CARB compared the annual precursor contributions to the 
EPA's recommended contribution threshold for the 2012 PM2.5 
NAAQS of 0.2 [micro]g/m\3\. For a modeled 30 percent VOC emissions 
reduction, the ambient PM2.5 responses in 2013 ranged from 
0.01 [micro]g/m\3\ to 0.16 [micro]g/m\3\ across 15 monitoring sites, 
with all sites below the 0.2 [micro]g/m\3\ contribution threshold.\166\ 
The 2020 and 2024 responses ranged from -0.07 [micro]g/m\3\ to 0.06 
[micro]g/m\3\, with all monitoring sites below the 0.2 [micro]g/m\3\ 
contribution threshold for both years. For a modeled 70 percent VOC 
emissions reduction, the PM2.5 responses in 2013 ranged from 
0.05 [micro]g/m\3\ to 0.40 [micro]g/m\3\, including responses at or 
above the 0.2 [micro]g/m\3\ contribution threshold at 8 of the 15 
sites. However, for 2020 and 2024 all responses were below the 0.2 
[micro]g/m\3\ contribution threshold; 2020 responses ranged from -0.10 
[micro]g/m\3\ to 0.16 [micro]g/m\3\ and the 2024 responses ranged from 
-0.18 [micro]g/m\3\ to 0.08 [micro]g/m\3\. The negative responses to 
VOC reductions represent an increase in PM2.5 levels, i.e., 
a disbenefit. The 2024 results show a disbenefit at 11 of the 15 sites 
for both the 30 percent and the 70 percent VOC emissions reductions 
scenarios.
---------------------------------------------------------------------------

    \166\ 2018 PM2.5 Plan, Appendix G, Table 10.
---------------------------------------------------------------------------

    CARB then considered additional information to assess whether these 
PM2.5 responses constituted a significant contribution to 
ambient PM2.5 in the San Joaquin Valley, including emissions 
trends and an assessment of the modeled disbenefit of VOC emissions 
reductions. VOC emissions are projected to decrease approximately 30 
tpd (or 9 percent) from 2013 to 2024, with approximately 28 out of the 
30 tpd reduction taking place by 2020.\167\ The State concludes that 
the formation of ambient PM2.5 from VOC may therefore differ 
in base and future years and that the sensitivity analysis for 2013, 
which showed some contributions above 0.2 [micro]g/m\3\, is not 
representative of current or future conditions.
---------------------------------------------------------------------------

    \167\ Id. at p. 19 and Figure 5.
---------------------------------------------------------------------------

    CARB explained the modeled disbenefit of VOC reductions as follows: 
emissions of VOC and NOX react in the atmosphere to form 
organic nitrate species, such as peroxyacetyl nitrate, meaning that 
some portion of the NOX emissions is not available to react 
with ammonia to form ammonium nitrate particulate matter. In other 
words, VOC emissions can be a ``sink'' for NOX emissions. 
Reducing VOC emissions therefore reduces the formation of organic 
nitrates, so the sink is smaller and nitrate molecules are freed to 
react with ammonia to form particulate ammonium nitrate.\168\ The State 
further explored the VOC disbenefit based on a 2016 CARB modeling 
assessment provided in Appendix A (``Air Quality Modeling'') of the 
``2016 Moderate Area Plan for the 2012 PM2.5 Standard'' for 
the San Joaquin Valley (``2016 PM2.5 Plan''), which CARB 
submitted to the EPA as a SIP revision on May 10, 2019.\169\
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    \168\ 15 [micro]g/m\3\ SIP Revision, Appendix K, pp. 81-82 
(citing Meng, Z., D. Dabdub, D., Seinfeld, J.H., Chemical Coupling 
Between Atmospheric Ozone and Particulate Matter, Science 277, 116 
(1997). DOI: 10.1126/science.277.5322.116).
    \169\ 2016 PM2.5 Plan, Appendix A, p. A-57. See also 
15 [micro]g/m\3\ SIP Revision, Appendix K, Section 5.7 
(``PM2.5 Precursor Sensitivity Analysis'').
---------------------------------------------------------------------------

    Based on its sensitivity-based analysis of VOC emissions 
reductions, VOC emissions trends, and the scientific understanding of 
VOC chemistry in the San Joaquin Valley, CARB concludes that VOC 
emissions do not contribute significantly to PM2.5 levels 
that exceed the 1997 annual PM2.5 NAAQS in the San Joaquin 
Valley.
3. The EPA's Review of the State's Submission
    The EPA has evaluated the State's precursor demonstration in the 
SJV PM2.5 Plan, consistent with the PM2.5 SIP 
Requirements Rule and the recommendations in the PM2.5 
Precursor Guidance. The State did not present a precursor demonstration 
for NOX, and indeed stated that controlling it is essential 
for the attainment strategy; \170\ NOX emission sources, 
therefore, remain subject to control requirements under subparts 1 and 
4 of part D, title I of the Act. For the reasons provided in the 
following paragraphs, the EPA proposes to approve the State's 
comprehensive demonstrations for ammonia, SOX, and VOC based 
on a conclusion that emissions of these precursor pollutants do not 
contribute significantly to ambient PM2.5 levels that exceed 
the 1997 annual PM2.5 NAAQS in the San Joaquin Valley. For 
further discussion of the EPA's evaluation of the precursor 
demonstration, please see the EPA's February 2020 Precursor TSD, which 
provides the EPA's summary of the State's precursor analyses for all 
four PM2.5 precursors.\171\
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    \170\ 2018 Plan Appendix G, p. 2.
    \171\ Much of the analysis in the EPA's February 2020 Precursor 
TSD is applicable to SJV PM2.5 Plan for the 1997 annual 
PM2.5 NAAQS. For example, the State's precursor 
demonstration used 2015 annual average concentration data for its 
concentration-based analysis, examined annual average sensitivities 
of ambient PM2.5 concentrations to reductions in each 
precursor in 2013, 2020, and 2024, and presented information on 
research studies and emission trends that are relevant for assessing 
the sensitivity of annual average ambient PM2.5 
concentrations to emission reductions of each PM2.5 
precursor. Our evaluation of such factors is similarly applicable 
for the 1997 annual PM2.5 NAAQS and we expand on such 
evaluation for purposes of those NAAQS specifically herein.
---------------------------------------------------------------------------

    The State based its analyses on the latest available data and 
studies concerning ambient PM2.5 formation in the San 
Joaquin Valley from precursor emissions. For the required 
concentration-based analysis, the State assessed the absolute annual 
average contribution of each precursor to ambient PM2.5 in 
2015. Given that the absolute concentrations in 2015 were above the 
EPA's recommended contribution thresholds for both the 2006 24-hour and 
2012 annual average NAAQS, the State proceeded with a sensitivity-based 
analysis, consistent with the recommendations in the PM2.5 
SIP Requirements Rule.
    For the sensitivity-based analysis, the State performed its 
analyses based on the EPA's recommended approach--i.e., for each 
modeled year and level of precursor emissions reduction (in 
percentages), the State estimated the ambient PM2.5 response 
using the procedure recommended in the PM2.5 Precursor 
Guidance. In particular, the State considered the EPA's recommended 
range of emissions reductions (30 percent to 70 percent) for the 2013 
base year, 2020 interim year, and 2024 future year, and quantified the 
estimated response of ambient PM2.5 concentrations to 
precursor emission changes in the San Joaquin Valley.
    The State's emissions projections in the 2018 PM2.5 Plan 
show that baseline emissions of each of these precursors will decrease 
from the 2013 base year to the 2023 attainment year. These decreases 
are included in the State's modeled projections of ambient 
PM2.5 levels in the San Joaquin Valley for purposes of 
demonstrating attainment and RFP. The State's sensitivity analyses are 
consistent with these projections, in accordance with the EPA's 
recommendations in the PM2.5 Precursor Guidance.\172\
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    \172\ PM2.5 Precursor Guidance, p. 35.
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    The EPA is proposing to find that such quantification and CARB's 
consideration of additional information provide an informed basis on 
which to make a determination as to whether ammonia, SOX, 
and VOC contribute significantly to ambient PM2.5 levels 
that exceed the 1997 annual PM2.5 NAAQS in the San Joaquin 
Valley.\173\ If we

[[Page 45292]]

finalize this proposal to approve the State's precursor demonstrations, 
the State will not be required to implement BACM/BACT level controls 
for sources of ammonia, SOX, and VOC for purposes of the SJV 
PM2.5 Plan for 1997 annual PM2.5 NAAQS that is 
the subject of this proposed action. Under 40 CFR 51.1006(b), such 
precursor demonstration approval would apply only to this attainment 
plan. For any new PM2.5 attainment plan that the State is 
required to submit in accordance with 40 CFR 51.1003 for purposes of 
any PM2.5 NAAQS, the State will be required to submit an 
updated precursor demonstration if it seeks to exempt sources of a 
particular precursor from control requirements in that attainment plan. 
In the subsections that follow, we summarize our evaluation of the 
State's precursor demonstrations for each of these three precursor 
pollutants.
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    \173\ The State did not evaluate the 2015 Serious area 
attainment year. Because the year has passed and the area failed to 
attain by the Serious area attainment date, we will evaluate the 
precursor analysis for the Serious area plan based on the current 
section 189(d) projected attainment date of December 31, 2023.
---------------------------------------------------------------------------

a. Ammonia
    We have evaluated CARB's sensitivity-based contribution analyses 
for 2013, 2020, and 2024 in the 2018 PM2.5 Plan and 
supplemental materials provided by the State, as well as CARB's 
determination that the 2024 results are representative of conditions in 
the San Joaquin Valley for purposes of a sensitivity-based analysis for 
the 1997 annual PM2.5 NAAQS. The EPA's PM2.5 
Precursor Guidance explicitly provides for consideration of a future 
year, and we are proposing to find that the State provided sufficient 
justification for relying on modeling results for 2024.\174\
---------------------------------------------------------------------------

    \174\ PM2.5 Precursor Guidance, p. 35.
---------------------------------------------------------------------------

    We also consider it appropriate for the State to take into account 
additional information as part of its evaluation of whether the ammonia 
contribution is significant and to rely on the responses to the 30 
percent modeled ammonia emissions reduction in its precursor 
demonstration for ammonia. The modeled PM2.5 response to the 
30 percent reduction is only marginally above the contribution 
threshold at a single monitoring site in 2024, and the EPA has evidence 
from the State and elsewhere that the response was overestimated, as 
discussed below. Together these suggest that ammonia does not 
contribute significantly to ambient PM2.5 levels. However, 
because the response is so close to the threshold at a 30 percent 
reduction, such a conclusion strongly depends on the emission reduction 
benefit of potential controls being 30 percent or less; larger 
reductions could give responses above the threshold. Therefore, per 40 
CFR 51.1010(a)(2)(ii), the EPA required an analysis of potential 
controls to aid the EPA in its evaluation of the precursor 
demonstration, which the State provided in the March 2023 Ammonia 
Supplement. The response of ambient PM2.5 to an actual 
assessment of the benefit from potential controls could then be used by 
the State to determine whether controlling ammonia would significantly 
affect PM2.5 levels.
    The State relied on the 2024 modeled ambient PM2.5 
responses to a 30 percent reduction in ammonia after concluding that 30 
percent was a reasonable upper bound on potential ammonia reductions, 
based on past research on ammonia emissions and its evaluation of 
potential control options. Based on the EPA's review of the State's 
rationale, including its ammonia control measure analysis, the EPA 
agrees that the reductions that the State could achieve through 
additional available BACM/BACT level controls on ammonia sources would 
be below 30 percent, and thus that the PM2.5 response to the 
ammonia emission reductions available would be below the contribution 
threshold at all sites for purposes of this plan, as discussed in the 
following paragraphs.\175\
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    \175\ Note that the task for the State is not to show whether 
controls could reduce ammonia by 30 percent, though that is the 
focus of the State's March 2023 Ammonia Supplement. The SIP 
requirements rule and the PM2.5 Precursor Guidance do not 
establish potential reductions of 30 percent as a ``bright line'' 
test for determining precursor significance. Rather, information 
from the control evaluation is to be used in conjunction with other 
information to determine whether ammonia reductions are effective in 
reducing PM2.5 levels, and so whether ammonia contributes 
significantly to PM2.5.
---------------------------------------------------------------------------

    The State compared the ammonia modeled sensitivity results in 
Appendix G of the 2018 PM2.5 Plan to the 0.2 [micro]g/m\3\ 
contribution threshold recommended by the EPA for the 2012 annual 
PM2.5 NAAQS in the PM2.5 Precursor Guidance. 
However, in the March 2023 Ammonia Supplement, the State also compared 
the model results against the 0.25 [micro]g/m\3\ contribution threshold 
it calculated based on the level of the 1997 annual PM2.5 
NAAQS. We find that the State's use of a 0.25 [micro]g/m\3\ threshold 
is consistent with the recommendations in the PM2.5 
Precursor Guidance,\176\ and is appropriate for purposes of evaluating 
the modeling results for the 1997 annual PM2.5 NAAQS, given 
the EPA's method of calculating the threshold and the level of the 1997 
annual PM2.5 NAAQS (15.0 [micro]g/m\3\).
---------------------------------------------------------------------------

    \176\ PM2.5 Precursor Guidance, fn. 20.
---------------------------------------------------------------------------

    The precursor demonstration in the SJV PM2.5 Plan 
indicates that the ambient response to a 30 percent ammonia emission 
reduction would exceed the 0.25 [micro]g/m\3\ contribution threshold 
for 13 out of 15 monitoring sites in the 2013 analysis year, and at 4 
out of 15 for the 2020 analysis year. For the 2024 analysis year, 1 of 
the 15 sites (Hanford) would exceed the contribution threshold. In 
absolute terms, the ambient PM2.5 response declines from 
0.24 [micro]g/m\3\ in 2020 to 0.12 [micro]g/m\3\ in 2024 at 
Bakersfield-Planz, the highest concentration site. The Hanford 
responses decline from 0.42 [micro]g/m\3\ in 2020 to 0.26 [micro]g/m\3\ 
in 2024. The average response over all monitoring sites declines from 
0.23 [micro]g/m\3\ to 0.14 [micro]g/m\3\, with the decline being 
generally larger for the sites with the highest projected 
PM2.5 levels.
    While the 2024 Hanford modeled response to a 30 percent ammonia 
reduction is above the contribution threshold, additional information 
about this location leads the EPA to give the response lower weight in 
the overall assessment of whether ammonia contributes significantly to 
PM2.5 levels. An independent study using aircraft and 
surface data from the winter 2013 DISCOVER-AQ \177\ campaign, a key 
period in the SJV PM2.5 Plan's 2013 model base case, found 
that the CMAQ model underestimated ammonia at Hanford by roughly a 
factor of five; Hanford is just outside a region with high ammonia 
emissions in the model (western Tulare County).\178\ If the modeled 
ammonia concentrations were higher to better match observations, there 
would be relatively more ammonia per NOX and the model 
response to ammonia reductions would be lower. This is consistent with 
CARB's conclusions regarding ammonia as described earlier.
---------------------------------------------------------------------------

    \177\ NASA, ``Deriving Information on Surface conditions from 
Column and VERtically Resolved Observations Relevant to Air 
Quality,'' described at https://www.nasa.gov/mission_pages/discover-aq/index.html.
    \178\ Kelly, J.T. et al. 2018, ``Modeling 
NH4NO3 over the San Joaquin Valley during the 
2013 DISCOVER-AQ campaign,'' Journal of Geophysical Research: 
Atmospheres, 123, pp. 4727-4745, https://doi.org/10.1029/2018JD028290 at 4733. The paper notes that, despite the ammonia 
underestimation, model performance was good for particulate ammonium 
nitrate and the ammonium nitrate was not sensitive to the ammonia 
underestimate since its formation was NOX-limited.
---------------------------------------------------------------------------

    In choosing which year's modeled response to ammonia to rely on, 
the EPA considered the State's point that the PM2.5 benefit 
of ammonia emission reductions is projected to decline steeply over 
time. We believe it is appropriate to consider changes in

[[Page 45293]]

atmospheric chemistry that may occur between the base or current year 
and the attainment year because the changes may ultimately affect the 
nonattainment area's progress toward expeditious attainment. The 
PM2.5 Precursor Guidance explicitly states that a future 
year may be used, and that there are a multitude of considerations in 
choosing the analysis year.\179\ The ``anticipated growth or loss of 
sources . . . or trends in ambient speciation data and precursor 
emissions'' \180\ are among the ``facts and circumstances of the area'' 
\181\ to consider in determining the significance of a precursor. The 
Guidance states that a future year could be more appropriate if it 
better represents the period that sources will operate in. As discussed 
in more detail below, the 2024 model results better represent the 
period that ammonia sources will operate in than 2013 and 2020 because 
of the steep decline in NOX emissions projected to occur by 
2023 and 2024. We consider it reasonable for the State to focus on the 
ambient PM2.5 response to ammonia emission reductions in 
2024, rather than 2013 or 2020, as the modeled response in 2024 in the 
San Joaquin Valley better reflects the potential benefit of ammonia 
control measures for purposes of expeditious attainment of the 1997 
annual PM2.5 NAAQS.
---------------------------------------------------------------------------

    \179\ PM2.5 Precursor Guidance, p. 35.
    \180\ Id. at 18.
    \181\ PM2.5 SIP Requirements Rule, 40 CFR 
51.1006(a)(1)(ii).
---------------------------------------------------------------------------

    The State's precursor demonstration in the SJV PM2.5 
Plan shows that ambient sensitivity to ammonia emissions reductions in 
the San Joaquin Valley declines steeply over time. Between 2020 and 
2024, the modeled response to a 30 percent ammonia emissions reduction 
declines by 50 percent at the Bakersfield-Planz monitoring site, which 
has the highest projected PM2.5 level, and by 37 percent 
averaged over all monitoring sites. As noted above, in absolute terms, 
the ambient PM2.5 response declines from 0.24 [micro]g/m\3\ 
in 2020 to 0.12 [micro]g/m\3\ in 2024 at Bakersfield-Planz, and from 
0.23 [micro]g/m\3\ to 0.14 [micro]g/m\3\ as averaged over all 
monitoring sites, with the decline being generally larger for the sites 
with the highest projected PM2.5 levels. Thus, between 2020 
and 2024, the number of sites at which modeled sensitivity exceeds the 
0.25 [micro]g/m\3\ threshold for the 1997 annual PM2.5 NAAQS 
declines from 4 out of 15 down to 1 out of 15.\182\ As discussed 
earlier, ammonia sensitivity declines because of the shifting 
atmospheric chemistry caused by NOX emissions decreases. 
NOX emissions are projected to decrease by 27 percent 
between 2020 and 2024 due to baseline measures (e.g., existing motor 
vehicle controls), with 91 percent of those emissions reductions 
occurring between 2020 and 2023.\183\ That is, NOX emissions 
in 2023 are 24 percent lower than NOX emissions in 2020 and 
3 percent higher than NOX emissions in 2024. Thus, 
conditions in 2024 are anticipated to be much more similar to those in 
2023 compared to 2020. The decreased NOX emissions will make 
ammonia more abundant relative to NOX, and even less of a 
limiting factor on PM2.5 formation. In other words, the 
model response in the future year 2024 gives a more realistic 
assessment of the potential effect of ammonia controls than past 
conditions.\184\
---------------------------------------------------------------------------

    \182\ 2018 PM2.5 Plan, Appendix G, tables 4 and 5.
    \183\ NOX emissions in 2020, 2023, and 2024 are 203.3 
tpd, 153.6 tpd, and 148.9 tpd, respectively.
    \184\ Since precursor sensitivity modeling results were not 
available for the specific year of 2023, the EPA estimated the 2023 
PM2.5 response to a 30 percent ammonia reduction using 
the modeling results for 2020 and 2024. As for the 2024 modeled 
sensitivities, we found that Hanford was the only site that would be 
above the 0.25 [micro]g/m\3\ contribution threshold for 2023, with a 
response of 0.27 [micro]g/m\3\. Thus, the results of this exercise 
do not change our conclusions. Spreadsheet ``Estimated 2023 annual 
PM2.5 sensitivity to ammonia reductions.xlsx,'' EPA 
Region IX, June 26, 2023.
---------------------------------------------------------------------------

    Additionally, the ambient studies described by the State and in 
independent research studies provide strong evidence that 
PM2.5 would respond only weakly to ammonia emissions 
reductions. As described above, those include a large measured excess 
of ammonia relative to the amount of nitrate available to interact with 
it to form PM2.5, and satellite and aircraft measurements 
indicating a larger amount of ammonia than is derived in model 
predictions. This evidence reflects actual measurements of the 
atmosphere, independent of uncertainties in the modeling and 
independent of estimates of ammonia and other emissions that are input 
to the model.
    Finally, the EPA has reviewed the additional information provided 
by the State to support its assertion that 30 percent is a reasonable 
upper bound on the ammonia reductions that could be achieved in the San 
Joaquin Valley and the State's reliance on the 30 percent sensitivity 
modeling results for the precursor demonstration for the 1997 annual 
PM2.5 NAAQS. The EPA proposes to find that the additional 
information adequately supports the conclusion that potential ammonia 
controls would yield less than a 30 percent reduction, such that the 
resulting decrease in ambient PM2.5 concentration would be 
below the contribution threshold. As discussed in Section IV.B.1 of 
this document, the PM2.5 Precursor Guidance indicates that 
the EPA may require air agencies to identify and evaluate potential 
emissions controls in support of a precursor demonstration that relies 
on a sensitivity analysis, particularly for an area in which the 
PM2.5 response to a 30 percent reduction in precursor 
emissions is close to the contribution threshold. For the San Joaquin 
Valley, the modeled response to a single site, Hanford, is just above 
the 0.25 [micro]g/m\3\ threshold for the 1997 annual PM2.5 
NAAQS at 0.26 [micro]g/m\3\. Furthermore, several analyses show ambient 
ammonia concentrations are underestimated at Hanford and so we believe 
that the 2024 modeled response of 0.26 [micro]g/m\3\ is likely 
overestimated. Supporting that conclusion is the evidence of the large 
ambient excess of ammonia relative to nitrate, which suggests that the 
actual PM2.5 response to reductions in ammonia emissions 
would be very small, and less than the response seen in the modeling. 
Thus, we conclude that in the San Joaquin Valley, the PM2.5 
response to a 30 percent reduction in ammonia emissions is close to the 
contribution threshold and that the State's approach to evaluate 
additional information in support of the precursor demonstration 
sensitivity analysis, including additional potential ammonia control 
measures, is consistent with the EPA's recommendations in the 
PM2.5 Precursor Guidance and responsive to the EPA's request 
for such additional information and analysis.
    As discussed in Section IV.B.2.a of this document, the State began 
its analysis to identify and evaluate potential emissions controls for 
ammonia by characterizing key ammonia source categories in the Valley 
(i.e., CAFs, agricultural fertilizers, and composting operations), and 
identifying existing rules that have resulted in ammonia emission 
reductions from these sources. Specifically, the State discusses the 
ammonia control effectiveness of a number of existing rules designed to 
reduce VOC emissions from these sources.\185\ While there are no 
ammonia-specific controls in place for these source categories, the EPA 
agrees with the District's information indicating that some of the 
management practices in the District's rules to reduce VOC emissions 
also reduce ammonia

[[Page 45294]]

emissions by limiting ammonia formation and volatilization.\186\
---------------------------------------------------------------------------

    \185\ 2018 PM2.5 Plan, Appendix C, pp. C-311 to C-
358.
    \186\ For example, see 2018 PM2.5 Plan, Appendix C, 
p. C-313 (for CAFs).
---------------------------------------------------------------------------

    Regarding the analysis for CAFs, we find that the District provided 
a thorough evaluation of potential ammonia mitigation measures by CAF 
type and activity through its comparison of the applicability and 
requirements of Rule 4570 with comparable rules that are being 
implemented in other air districts and its review of scientific 
research studies. In considering the technical feasibility of each 
identified measure, the District assessed factors such as how the 
measure compares with requirements already being implemented under 
District Rule 4570, the compatibility of the measure with the types of 
CAFs operating in the Valley (considering, for example, CAF size and 
common practices employed), compatibility of the measure with the 
climate conditions in the Valley, and any cobenefits and/or undesirable 
consequences of implementing the measure.
    Based on its evaluation, the District determined that several 
measures identified in the literature are already required in the San 
Joaquin Valley by Rule 4570 (e.g., washing floors and other soiled 
areas in livestock facilities), or by other State regulations (e.g., 
requirements to carefully time manure application as required by the 
California Regional Water Quality Control Board).187 188 For 
measures that the District identified as feasible for implementation in 
the San Joaquin Valley, the District provided information detailing how 
it estimated the potential ammonia emission reductions that could be 
achieved based on control efficiencies cited in the literature. For 
measures that the State determined to be infeasible in the San Joaquin 
Valley, the District provided a narrative justification for its 
conclusion.
---------------------------------------------------------------------------

    \187\ March 2023 Ammonia Supplement, pp. 47-49.
    \188\ Id. at 77.
---------------------------------------------------------------------------

    Reasons for concluding that a particular measure is infeasible 
included that the measure is not conducive to the type, size, or 
standard practices of CAFs operating in the Valley; the measure is not 
compatible with the hot, dry, drought climate conditions in the Valley; 
the measure is not economically feasible; or that the measure would 
have undesirable consequences (e.g., adverse effects on water quality, 
reduced dairy cattle milk production). The District also concluded that 
more research is needed to examine the technical and/or economic 
feasibility of implementing some of the measures in the Valley 
specifically. For those measures that the District found to be 
economically infeasible (e.g., biofilters and wet scrubbers, 
oxygenation of liquid manure lagoons), it provided detailed cost 
analyses to support its assertion.\189\ Based on our review of the 
District's controls analysis for CAFs, we find that the District 
provided a robust analysis of its Rule 4570 and a thorough review of 46 
possible mitigation measures for reducing ammonia emissions from CAFs 
in the San Joaquin Valley.
---------------------------------------------------------------------------

    \189\ Id. at 59-60 and Appendix B.
---------------------------------------------------------------------------

    For fertilizer application, the State emphasizes that it has not 
identified any SIP-approved requirements that are being implemented in 
other areas. Thus, it describes regulations adopted by other California 
State agencies to control fertilizer application, such as regulations 
adopted by the California Water Resources Board, and otherwise focuses 
its review on several research studies on reducing ammonia emissions 
from synthetic fertilizer application. Based on its review of 
mitigation options in the literature, the State concludes that some of 
the mitigation strategies are already required by current State 
regulations, and that further research is needed to explore the 
feasibility and effectiveness of those measures that are not currently 
in practice.
    Regarding State regulations that are currently in place to control 
fertilizer application, we generally agree with the State that those 
regulations are likely to enhance the retention of nitrogen from manure 
and nitrogen-based chemical fertilizers in the San Joaquin Valley and 
to limit the loss of nitrogen as pollution to water and air, thereby 
potentially reducing ammonia emissions. Additionally, as discussed 
earlier, District Rules 4570 and 4565 have provisions that reduce 
ammonia emissions by addressing the land application of manure from 
CAFs and of biosolids, animal manure, and poultry litter from 
composting operations. The EPA believes that the State's review of both 
existing ammonia mitigation measures and the research literature is an 
appropriate and thorough method for identifying potential measures. We 
also believe it reasonable that the State concludes that several of the 
specific mitigation strategies identified in the literature, such as 
optimizing fertilizer use, are already being implemented in the San 
Joaquin Valley due to these current State regulations and co-benefits 
such as reduced cost to farmers, and that more research is needed to 
assess the feasibility of other additional measures identified. Based 
on our review, and the fact that the State did not identify any ammonia 
mitigation measures for fertilizer application being implemented in 
other areas, we conclude that the State's overall conclusions are 
reasonable.
    For composting and other sources, the District notes that 
significant ammonia reductions are already being achieved by existing 
rules, including a 44 percent reduction from composting operations from 
Rules 4565 and 4566, and reductions from mobile source and fuel 
combustion measures. As discussed earlier, the EPA agrees that Rules 
4565 and 4566 have reduced ammonia emissions in the Valley. We also 
agree that the State's stringent controls for on-road mobile sources 
have resulted in ammonia reductions from those sources. While the State 
continues to work to reduce emissions from mobile sources to reduce 
NOX and other pollutants in the Valley, since on-road mobile 
sources account for approximately one percent of the ammonia emissions 
inventory,\190\ any ammonia reductions achievable through additional 
on-road mobile source controls would be small. The District states that 
it did not identify any additional potential mitigation measures for 
these source categories.
---------------------------------------------------------------------------

    \190\ 2018 PM2.5 Plan, Appendix B, Table B-5.
---------------------------------------------------------------------------

    While we generally find that the State provided a robust review of 
existing regulations and potential additional mitigation measures in 
the research literature, we note that a limitation of the District's 
analysis is that there remains some uncertainty as to how much 
reduction is currently being achieved by State and District rules and 
thus if some incremental additional reduction may be available. For 
fertilizer application specifically, the District does not attempt to 
quantify or otherwise substantiate the scale of ammonia emission 
reductions from existing regulations, nor their enforceability, which 
confounds the prospects for quantifying how much additional reductions 
may be available. Furthermore, while the District provides a detailed 
controls analysis for CAFs, with regard to Rule 4570, as the EPA has 
previously noted,\191\ the State has not sufficiently substantiated its 
calculation of the 100 tpd of ammonia emission reductions attributed to 
Rule 4570. In the 2018 PM2.5 Plan, the State references an 
analysis from 2006 that relied on a different baseline emissions 
inventory, but has not supplemented this analysis, or reconciled it 
with more recent

[[Page 45295]]

emissions inventory data.\192\ While the EPA agrees that meaningful 
ammonia reductions have been achieved from Rule 4570, there remains 
some uncertainty as to the precise magnitude of those reductions. 
Notwithstanding this uncertainty, as discussed in more detail below, 
given the scarcity of additional feasible measures identified by the 
State, and the scale of potential additional emissions reductions 
available in the context of the sensitivity of PM2.5 to 
ammonia reductions in the nonattainment area for the 1997 annual 
PM2.5 NAAQS, we find that the controls analysis provided by 
the State is sufficient to support its conclusion that that ammonia 
emissions do not contribute significantly to ambient PM2.5 
levels that exceed the 1997 annual PM2.5 NAAQS in the San 
Joaquin Valley.
---------------------------------------------------------------------------

    \191\ 81 FR 69396, 69397-69398 (October 6, 2016) and 87 FR 
60494, 60503-60504 (October 5, 2022).
    \192\ 2018 PM2.5 Plan, Appendix C, pp. C-311 to C-339 
and SJVUAPCD, ``Final Draft Staff Report, Proposed Re-Adoption of 
Rule 4570 (Confined Animal Facilities),'' June 18, 2009, at Appendix 
F, ``Ammonia Reductions Analysis for Proposed Rule 4570 (Confined 
Animal Facilities),'' June 15, 2006 (discussing various assumptions 
underlying the District's calculation of ammonia emission factors 
without identifying relevant emissions inventories).
---------------------------------------------------------------------------

    Based on its analysis, the State concludes that significant ammonia 
reductions have already been achieved in the San Joaquin Valley through 
existing State regulations and standard practices, and that the 
potential additional ammonia emissions reductions achievable through 
the implementation of additional best available controls is two percent 
of the total ammonia emissions in the San Joaquin Valley. This value is 
well below the lower end (i.e., 30 percent) of the ammonia reductions 
that the State modeled for analytical purposes for its sensitivity-
based analysis. While there remains some uncertainty as to the ammonia 
reductions that are currently being achieved by existing rules and 
standard practices, and thus the additional reductions that could be 
achieved by those rules and practices, we believe the State has 
provided sufficient evidence to support its assertion that the 
additional available reductions are less than 30 percent.
    Specifically, the District has made a convincing case that 
significant ammonia reductions have already been achieved through 
District Rule 4570 and that few additional mitigation measures could 
provide only modest further reductions from CAFs, which account for 58 
percent of the total ammonia inventory. Similarly, the State has 
provided support for its assertion that additional reductions are not 
feasible from the fertilizer, composting, and other smaller source 
categories through its analysis of potential fertilizer controls, in 
particular, in addition to information regarding controls that are 
already in place for these source categories.\193\ Based on our review 
of the analysis, we conclude that the potential reduction from 
available controls would be well below 30 percent. Given that the 
State's modeled sensitivities of PM2.5 concentrations to a 
30 percent ammonia reduction are approximately at or below the 
threshold used for identifying an impact that is significant for the 
1997 annual PM2.5 NAAQS, and that potential reductions would 
be below 30 percent, the EPA agrees that the response of 
PM2.5 to an ammonia reduction of a percentage smaller than 
30 percent would be below the contribution threshold, indicating that 
ammonia does not contribute significantly to ambient PM2.5 
concentrations for purposes of the SJV PM2.5 Plan for the 
1997 annual PM2.5 NAAQS.
---------------------------------------------------------------------------

    \193\ The State has not provided an estimate of the reductions 
that are currently being achieved for the fertilizer category, which 
accounts for 34 percent of the total ammonia emissions inventory. 
Nevertheless, even if ammonia emissions from fertilizers could be 
reduced by a very high percentage (e.g., 70 percent), that would 
correspond to a smaller percentage reduction of the total ammonia 
emissions. Such conservatively high reductions from fertilizers 
added to the potential ammonia reductions from CAFs identified by 
the State would still amount to less than a 30 percent reduction of 
the total ammonia emissions.
---------------------------------------------------------------------------

    In summary, we conclude that the State quantified the sensitivity 
of ambient PM2.5 levels to reductions in ammonia emissions 
using appropriate modeling techniques, the modeled response to ammonia 
reductions is likely lower than reported, and the State's choice of 
2024 as the reference point for purposes of evaluating the sensitivity 
of ambient PM2.5 levels to ammonia emissions reductions is 
well-supported. The State also provided strong evidence to support its 
conclusion that additional controls on ammonia sources would achieve 
ammonia emissions reductions well below 30 percent, including its 
estimate, following review of the measures the State and District 
consider feasible, that the reductions available are approximately 2 
percent. Since the modeled ambient PM2.5 response to a 30 
percent ammonia reduction is only marginally above the contribution 
threshold at a single monitoring site, that response may be 
overestimated, and potential reductions are below 30 percent, the 
PM2.5 response to additional ammonia controls would be below 
the contribution threshold. Based on these considerations, the EPA 
proposes to approve the State's demonstration that ammonia emissions do 
not contribute significantly to ambient PM2.5 levels that 
exceed the 1997 annual PM2.5 NAAQS in the San Joaquin 
Valley.
    We note that this proposed determination is specific to the facts 
and circumstances of this particular plan--including but not limited to 
the specific level of the 1997 annual PM2.5 NAAQS and the 
proportional modeling response needed to be considered significant, the 
State's modeling indicating that ammonia levels the San Joaquin Valley 
are at or below the contribution threshold for the 1997 annual 
PM2.5 NAAQS, the unique atmospheric conditions in the Valley 
in which the PM2.5 response to reductions in ammonia 
emissions would be relatively small, the demonstration that 
the potential reductions from additional control measures that are not 
currently being implemented would be below 30 percent, and the current 
limited research in key areas of ammonia controls--and that it does not 
pre-determine the outcome of significance determinations of precursors 
in the future.
b. SOX
    For SOX, the 2018 PM2.5 Plan's sensitivity 
estimates for 2013 are well below the EPA's recommended threshold for 
both the 30 percent and 70 percent emission reduction scenarios and are 
even negative for some monitoring sites. Given those results and the 
steady SOX emission levels over 2013 to 2023 (as opposed to 
increases), the EPA agrees with the State's conclusion that the 2013 
modeled sensitivities provide a sufficient basis for the SOX 
precursor demonstration. The supplemental results provided by the State 
for 2020 and 2024 support this conclusion.
    Therefore, based on these modeled ambient PM2.5 
responses to SOX emissions reductions in the San Joaquin 
Valley, and on the facts and circumstances of the area, the EPA 
proposes to approve the State's demonstration that SOX 
emissions do not contribute significantly to ambient PM2.5 
levels that exceed the 1997 annual PM2.5 NAAQS in the San 
Joaquin Valley. We note that this proposed determination is specific to 
the facts and circumstances of this particular plan and that it does 
not pre-determine the outcome of significance determinations of 
precursors in the future.
c. VOC
    For VOC, the State found that the ambient PM2.5 response 
to VOC emissions reductions were generally

[[Page 45296]]

below the EPA's recommended contribution threshold of 0.2 [mu]g/m\3\, 
and predicted an increase in ambient PM2.5 levels in 
response to VOC reductions (i.e., a disbenefit) at 2 out of 15 
monitoring sites in 2020, and at 11 out 15 sites in 2024. Only for a 70 
percent emissions reduction for the 2013 base year did the State 
predict the ambient PM2.5 response to be above the threshold 
at a majority of sites.\194\
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    \194\ 2018 PM2.5 Plan, Appendix G, tables 10 and 11.
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    The EPA has evaluated and agrees with the State's determination in 
the 2018 PM2.5 Plan that the modeling for future years is 
more representative of conditions in the San Joaquin Valley than the 
2013 modeling for sensitivity-based analyses and the State's resulting 
conclusion that the contribution from VOC emissions is not significant. 
The EPA agrees that the 8.6 percent decrease in VOC emissions from 2013 
to 2020 and the 9.2 percent projected decrease from 2013 to 2024 favors 
reliance on the future year modeling results. Furthermore, there is a 
large decrease in NOX emissions over this period, as 
discussed in Section IV.B.2 of this proposed rule, that affects the 
atmospheric chemistry with respect to ambient PM2.5 
formation from VOC emissions. The 9.2 percent VOC emissions reductions 
and the vast majority of NOX emissions reductions are 
expected to result from baseline measures already in effect. Therefore, 
we conclude that it is reasonable to rely on future year 2020 or 2024 
modeled responses to VOC emissions reductions. The EPA also concludes 
that the State provided a reasonable explanation for the VOC emissions 
reduction disbenefit and evidence that it occurs in the San Joaquin 
Valley.
    For these reasons, we propose to approve the State's demonstration 
that VOC emissions do not contribute significantly to ambient 
PM2.5 levels that exceed the 1997 annual PM2.5 
NAAQS in the San Joaquin Valley. We note that this proposed 
determination is specific to the facts and circumstances of this 
particular plan and that it does not pre-determine the outcome of 
significance determinations of precursors in the future.

C. Attainment Plan Control Strategy

1. Statutory and Regulatory Requirements
    Section 189(b)(1)(B) of the Act requires for any Serious 
PM2.5 nonattainment area that the state submit provisions to 
assure that best available control measures (BACM), including controls 
that reflect best available control technology (BACT), for the control 
of PM2.5 and PM2.5 precursors shall be 
implemented no later than four years after the date the area is 
reclassified as a Serious area. The EPA has defined BACM in the 
PM2.5 SIP Requirements Rule to mean ``any technologically 
and economically feasible control measure that can be implemented in 
whole or in part within four years after the date of reclassification 
of a Moderate PM2.5 nonattainment area to Serious and that 
generally can achieve greater permanent and enforceable emissions 
reductions in direct PM2.5 emissions and/or emissions of 
PM2.5 plan precursors from sources in the area than can be 
achieved through the implementation of RACM on the same source(s). BACM 
includes best available control technology (BACT).'' \195\
---------------------------------------------------------------------------

    \195\ 40 CFR 51.1000 (definitions). In longstanding guidance, 
the EPA has similarly defined BACM to mean, ``among other things, 
the maximum degree of emissions reduction achievable for a source or 
source category, which is determined on a case-by-case basis 
considering energy, environmental, and economic impacts.'' General 
Preamble Addendum, 42010, 42013.
---------------------------------------------------------------------------

    Because the 2015 Serious area attainment date has passed, and the 
EPA found that the area failed to attain by the Serious area attainment 
date, we are evaluating the submission for compliance with the BACM/
BACT requirements now, in conjunction with the State's SIP submission 
intended to meet both the Serious area and section 189(d) plan 
requirements.
    The EPA generally considers BACM a control level that goes beyond 
existing RACM-level controls, for example by expanding the use of RACM 
controls or by requiring preventative measures instead of 
remediation.\196\ Indeed, because states are required to implement BACM 
and BACT when a Moderate nonattainment area is reclassified as Serious 
due to its inability to attain the NAAQS through implementation of 
``reasonable'' measures, it is logical that ``best'' control measures 
should represent a more stringent and potentially more technologically 
advanced or more costly level of control.\197\ If RACM and RACT level 
controls of emissions have been insufficient to reach attainment, then 
the CAA title I, part D, subpart 4 provisions for PM2.5 
nonattainment plans contemplate the implementation of more stringent 
controls, controls on more sources, or other adjustments to the control 
strategy are necessary to attain the NAAQS in the area. Thus, BACM/BACT 
determinations are to be ``generally independent'' of attainment for 
purposes of implementing the PM2.5 NAAQS.\198\
---------------------------------------------------------------------------

    \196\ 81 FR 58010, 58081 and General Preamble Addendum, 42011, 
42013.
    \197\ Id. and General Preamble Addendum, 42009-42010.
    \198\ PM2.5 SIP Requirements Rule, 58081-58082. See 
also, General Preamble Addendum, 42011.
---------------------------------------------------------------------------

    Under the PM2.5 SIP Requirements Rule, those control 
measures that otherwise meet the definition of BACM/BACT but ``can only 
be implemented in whole or in part beginning four years after 
reclassification'' are referred to as ``additional feasible measures.'' 
\199\ In accordance with the requirements of CAA section 172(c)(6), a 
Serious area plan must include any additional feasible measures to 
control emissions of direct PM2.5 and PM2.5 
precursors that are necessary and appropriate to provide for attainment 
of the relevant NAAQS as expeditiously as practicable and no later than 
the applicable attainment date.\200\
---------------------------------------------------------------------------

    \199\ 40 CFR 51.1000, 40 CFR 51.1010(a)(4)(ii).
    \200\ Because the Serious area attainment year has passed and 
the area failed to attain by the Serious area attainment date, we 
will evaluate the BACM/BACT and additional feasible measure analysis 
for the Serious area plan with respect to the current section 189(d) 
projected attainment date of December 31, 2023.
---------------------------------------------------------------------------

    Consistent with longstanding guidance provided in the General 
Preamble Addendum, the preamble to the PM2.5 SIP 
Requirements Rule discusses the following steps for states to follow to 
identify and select emission controls needed to meet the BACM/BACT and 
additional feasible measures requirements of 40 CFR 51.1010:
    (1) Develop a comprehensive emissions inventory of all sources of 
PM2.5 and PM2.5 precursors from major and non-
major stationary point sources, area sources, and mobile sources;
    (2) Identify potential control measures for all sources or source 
categories of emissions of PM2.5 and relevant 
PM2.5 plan precursors;
    (3) Determine whether an available control measure or technology is 
technologically feasible;
    (4) Determine whether an available control measure or technology is 
economically feasible; and
    (5) Determine the earliest date by which a control measure or 
technology can be implemented in whole or in part.\201\
---------------------------------------------------------------------------

    \201\ 81 FR 58010, 58083-58085.
---------------------------------------------------------------------------

    The EPA allows states to consider factors such as a source's 
processes and operating procedures, raw materials, physical plant 
layout, and potential environmental effects such as increased water 
pollution, waste disposal, and energy requirements when considering 
technological feasibility.\202\ For purposes of evaluating economic

[[Page 45297]]

feasibility, the EPA allows states to consider factors such as the 
capital costs, operating and maintenance costs, and cost effectiveness 
(i.e., cost per ton of pollutant reduced by a measure or technology) 
associated with the measure or control.\203\ For any potential control 
measure identified through the process described above that is 
eliminated from consideration, states are required to provide detailed 
written justification for doing so on the basis of technological or 
economic feasibility, including how its criteria for determining such 
feasibility are more stringent than those used for determining RACM/
RACT.\204\
---------------------------------------------------------------------------

    \202\ 40 CFR 51.1010(a)(3)(i).
    \203\ 40 CFR 51.1010(a)(3)(ii).
    \204\ 40 CFR 51.1010(a)(3)(iii).
---------------------------------------------------------------------------

    Once these analyses are complete, the state must use this 
information to develop enforceable control measures for all relevant 
source categories in the nonattainment area and submit them to the EPA 
for evaluation as SIP provisions to meet the basic requirements of CAA 
section 110 and any other applicable substantive provisions of the Act. 
The EPA is using these steps as guidelines in the evaluation of the 
BACM and BACT measures and related analyses in the SJV PM2.5 
Plan. Furthermore, because the EPA has not previously taken action to 
approve the California SIP as meeting the subpart 4 Moderate area 
planning requirements under CAA section 189 for the 1997 annual 
PM2.5 NAAQS for the San Joaquin Valley area, the EPA is 
reviewing the SJV PM2.5 Plan for compliance with those 
requirements.\205\
---------------------------------------------------------------------------

    \205\ The EPA does not normally conduct a separate evaluation to 
determine whether a Serious area plan's measures also meet the RACM 
requirements. As explained in the General Preamble Addendum, we 
interpret the BACM requirement as generally subsuming the RACM 
requirement--i.e., if we determine that the measures are indeed the 
``best available,'' we have necessarily concluded that they are 
``reasonably available.'' (General Preamble Addendum, 42010). 
Therefore, a separate analysis to determine if the measures 
represent a RACM level of control is not necessary. A proposed 
approval of a Plan's provisions concerning implementation of BACM is 
also a proposed finding that the Plan provides for the 
implementation of RACM.
---------------------------------------------------------------------------

    The overarching requirement for the CAA section 189(d) attainment 
control strategy is that it provides for attainment of the NAAQS as 
expeditiously as practicable.\206\ The control strategy must include 
any additional measures (beyond those already adopted in previous 
nonattainment plans for the area as RACM/RACT or BACM/BACT) that are 
needed for the area to attain expeditiously. This includes reassessing 
any measures previously rejected during the development of any Moderate 
area or Serious area attainment plan control strategy.\207\ The state 
must also demonstrate that it will, at a minimum, achieve an annual 
five percent reduction in emissions of direct PM2.5 or any 
PM2.5 plan precursor from sources in the area, based on the 
most recent emissions inventory for the area.\208\
---------------------------------------------------------------------------

    \206\ 81 FR 58010, 58100.
    \207\ 40 CFR 50.1010(c)(2)(ii).
    \208\ CAA section 189(d) and 40 CFR 51.1010(c).
---------------------------------------------------------------------------

    In the PM2.5 SIP Requirements Rule, the EPA clarified 
its interpretation of the statutory language in CAA section 189(d) 
requiring a state to submit a new attainment plan to achieve annual 
reductions ``from the date of such submission until attainment,'' to 
mean annual reductions beginning from the due date of such submission 
until the new projected attainment date for the area based on the new 
or additional control measures identified to achieve at least five 
percent emissions reductions annually.\209\ This interpretation is 
intended to make clear that even if a state is late in submitting its 
CAA section 189(d) plan, the area must still achieve its annual five 
percent emissions reductions beginning from the date by which the state 
was required to make its CAA section 189(d) submission, not by some 
later date. Because the deadline for California to submit a section 
189(d) plan for the 1997 annual PM2.5 NAAQS in the San 
Joaquin Valley was December 31, 2016, one year after the December 31, 
2015 attainment date for these NAAQS under CAA section 188(c)(2), the 
starting point for the five percent emissions reduction requirement 
under section 189(d) for this area is 2017.
---------------------------------------------------------------------------

    \209\ 81 FR 58010, 58101.
---------------------------------------------------------------------------

2. Summary of the State's Submission and the EPA's Evaluation and 
Proposed Action
a. Control Strategy
i. Baseline Measures
    The control strategy in the SJV PM2.5 Plan is based 
largely on ongoing emissions reductions from baseline control measures, 
which amount to approximately 98.2 percent of total NOX 
emissions reductions and 93.3 percent of total direct PM2.5 
emissions reductions modeled to result in attainment of the 1997 annual 
PM2.5 NAAQS in the San Joaquin Valley.210 211 As 
we use the term here, baseline measures are State and District 
regulations adopted prior to the development of the 2018 
PM2.5 Plan that continue to achieve emissions reductions 
through the projected 2023 attainment year for the 1997 annual 
PM2.5 NAAQS and beyond. The State describes these baseline 
measures in the 15 [mu]g/m\3\ SIP Revision in Chapter 4 (``Attainment 
Strategy for PM2.5'') \212\ and Appendix D (``Mobile Source 
Control Measure Analyses''), and in Appendix C (``Stationary Source 
Control Measure Analyses'') of the 2018 PM2.5 Plan. The 
State incorporates reductions generated by these baseline measures into 
the projected baseline inventories, and reductions resulting from 
District measures are individually quantified in Appendix C. Table 4 
provides a summary of the 2013 base year emissions and the reductions 
from baseline measures, additional State measures, and additional 
District measures that the Plan projects will result in attainment of 
the 1997 annual PM2.5 NAAQS in the San Joaquin Valley by 
December 31, 2023.
---------------------------------------------------------------------------

    \210\ Because the 2015 Serious area attainment date has passed, 
and the EPA found that the area failed to attain by the Serious area 
attainment date, we are evaluating the control strategy for the 
Serious area requirements based on the timeline associated with the 
current section 189(d) projected attainment date of December 31, 
2023.
    \211\ The EPA calculated these percentages as follows: annual 
average baseline NOX reductions from 2013 to 2023 are 
163.6 tpd of 166.6 tpd modeled to result in attainment (98.2 
percent) and annual average baseline direct PM2.5 
reductions are 4.2 tpd of 4.5 tpd modeled to result in attainment 
(93.3 percent). 2018 PM2.5 Plan, Appendix B; and 15 
[mu]g/m\3\ SIP Revision, Chapter 4 and Appendix K.
    \212\ 15 [mu]g/m\3\ SIP Revision, Chapter 4, Table 4-2.

   Table 4--Summary of the SJV PM2.5 Plan's Annual Average Emission Reductions To Attain the 1997 Annual PM2.5
                                           NAAQS by December 31, 2023
----------------------------------------------------------------------------------------------------------------
                                                                  % of 2013 base   Direct PM2.5   % of 2013 base
                                                    NOX  (tpd)       year NOX          (tpd)        year PM2.5
                                                                     emissions                       emissions
----------------------------------------------------------------------------------------------------------------
A.............................  2013 Base Year             317.2  ..............            62.5  ..............
                                 Emissions.
B.............................  Baseline Measure           163.6            51.6             4.2             6.7
                                 Emissions
                                 Reductions
                                 (2013-2023).
C.............................  Additional CARB              3.0             0.9             0.1             0.2
                                 Measures.

[[Page 45298]]

 
D.............................  Additional                   0.0             0.0             0.2             0.3
                                 District
                                 Measures.
E.............................  Total 2013-2023            166.6            52.5             4.5             7.2
                                 Emissions
                                 Reductions
                                 (B+C+D).
----------------------------------------------------------------------------------------------------------------
Source: 2018 PM2.5 Plan, Appendix B, tables B-1 and B-2; and 15 [mu]g/m\3\ SIP Revision, Appendix K, Table 32.

    In the SJV PM2.5 Plan, the State explains that mobile 
sources emit over 85 percent of the NOX emissions in the San 
Joaquin Valley and that CARB has adopted and amended regulations to 
reduce public exposure to emissions from diesel vehicles and engines, 
which include direct PM2.5 and NOX, from ``fuel 
sources, freight transport sources like heavy-duty diesel trucks, 
transportation sources like passenger cars and buses, and non-road 
sources like large construction equipment.'' \213\
---------------------------------------------------------------------------

    \213\ 15 [mu]g/m\3\ SIP Revision, Chapter 4, p. 4-9. For CARB's 
BACM analysis for mobile source measures, see 15 [mu]g/m\3\ SIP 
Revision, Appendix D, including analyses for on-road light-duty 
vehicles and fuels (starting on page D-17), on-road heavy-duty 
vehicles and fuels (starting on page D-35), and non-road sources 
(starting on page D-64).
---------------------------------------------------------------------------

    Given the need for substantial emissions reductions from mobile and 
area sources to meet the NAAQS in California nonattainment areas, the 
State of California has developed stringent control measures for on-
road and non-road mobile sources and the fuels that power them. 
California has unique authority under CAA section 209 (subject to a 
waiver by the EPA) to adopt and implement new emissions standards for 
many categories of on-road vehicles and engines and new and in-use non-
road vehicles and engines. The EPA has issued numerous waivers and 
authorizations for California's mobile source regulations and has 
approved many such mobile source regulations as revisions to the 
California SIP.\214\
---------------------------------------------------------------------------

    \214\ For example, see 81 FR 39424 (June 16, 2016); 82 FR 14446 
(March 21, 2017); 83 FR 23232 (May 18, 2018); and 88 FR 20688 (April 
6, 2023).
---------------------------------------------------------------------------

    CARB's mobile source program extends beyond regulations that are 
subject to the waiver or authorization process set forth in CAA section 
209 to include standards and other requirements to control emissions 
from in-use heavy-duty trucks and buses, gasoline and diesel fuel 
specifications, and many other types of mobile sources. Generally, 
these regulations have also been submitted by the State and approved by 
the EPA as revisions to the California SIP.\215\
---------------------------------------------------------------------------

    \215\ For example, see the EPA's approval of standards and other 
requirements to control emissions from in-use heavy-duty diesel 
trucks (77 FR 20308, April 4, 2012) and revisions to the California 
on-road reformulated gasoline and diesel fuel regulations (75 FR 
26653, May 12, 2010).
---------------------------------------------------------------------------

    As to stationary and area sources, the State asserts in the SJV 
PM2.5 Plan that stringent regulations adopted for prior 
attainment plans continue to reduce emissions of NOX and 
direct PM2.5.\216\ Specifically, Table 4-1 of the 15 [mu]g/
m\3\ SIP Revision identifies 33 District measures that limit 
NOX and direct PM2.5 emissions.\217\ The EPA has 
approved each of the identified measures into the California SIP,\218\ 
with two exceptions.
---------------------------------------------------------------------------

    \216\ 15 [mu]g/m\3\ SIP Revision, Chapter 4, p. 4-3. For the 
District's BACM analysis of stationary and area source measures, see 
2018 PM2.5 Plan, Appendix C.
    \217\ 15 [mu]g/m\3\ SIP Revision, Chapter 4, Table 4-1.
    \218\ See EPA Region IX's website for information on District 
control measures that have been approved into the California SIP, 
available at: https://www.epa.gov/sips-ca/epa-approved-san-joaquin-valley-unified-air-district-regulations-california-sip.
---------------------------------------------------------------------------

    First, the District amended Rule 4905 (``Natural Gas-fired, Fan-
type, Residential Central Furnaces'') on June 21, 2018, to extend the 
period during which manufacturers may pay emissions fees in lieu of 
meeting the rule's NOX emissions limits.\219\ CARB submitted 
the amended rule to the EPA on November 21, 2018. However, the District 
amended Rule 4905 again on October 15, 2020, to further extend the 
period during which manufacturers of weatherized furnaces must pay 
emission fees in lieu of meeting the rule's NOX emissions 
limits.\220\ CARB submitted the rule as amended on October 15, 2020, to 
the EPA on December 30, 2020, and simultaneously withdrew the rule as 
amended June 21, 2018.\221\ The District amended Rule 4905 once more on 
December 16, 2021, to further extend the implementation period and CARB 
submitted the amended version to the EPA on March, 9, 2022.\222\ The 
EPA has not yet proposed any action on either the December 30, 2020 or 
the March 9, 2022 versions.
---------------------------------------------------------------------------

    \219\ SJVUAPCD, Final Draft Staff Report, ``Proposed Amendments 
to Rule 4905 (Natural Gas-fired, Fan-type Central Furnaces),'' June 
21, 2018, p. 2.
    \220\ SJVUAPCD, ``Item Number X: Adopt Proposed Amendments to 
Rule 4905 (Natural Gas-Fired, Fan-Type Furnaces),'' October 15, 
2020, p. 3, including Final Draft Staff Report, ``Proposed 
Amendments to Rule 4905 (Natural Gas-Fired, Fan-Type Furnaces).''
    \221\ Letter dated December 28, 2020, from Richard W. Corey, 
Executive Officer, CARB, to John Busterud, Regional Administrator, 
EPA Region 9.
    \222\ Letter dated March 9, 2022, from Richard W. Corey, 
Executive Officer, CARB, to Martha Guzman, Regional Administrator, 
EPA Region IX.
---------------------------------------------------------------------------

    The EPA approved a prior version of Rule 4905 into the California 
SIP on March 29, 2016.\223\ As part of that rulemaking, the EPA noted 
that because of the option in Rule 4905 to pay mitigation fees in lieu 
of compliance with emissions limits, emissions reductions associated 
with the rule's emissions limits would not be creditable in any 
attainment plan without additional documentation.\224\ Until the 
District submits the necessary documentation to credit emissions 
reductions achieved by Rule 4905 toward an attainment control strategy, 
this rule is not creditable for SIP purposes. The Plan indicates that 
the District attributed annual average emission reductions of 0.2 tpd 
of NOX reductions between 2013 and 2023 to Rule 4905.\225\ 
These emissions reductions would not materially affect the attainment 
demonstration for the 1997 annual PM2.5 NAAQS in the SJV 
PM2.5 Plan.
---------------------------------------------------------------------------

    \223\ 81 FR 17390 (March 29, 2016) (approving Rule 4905 as 
amended January 22, 2015).
    \224\ EPA, Region IX Air Division, ``Technical Support Document 
for EPA's Proposed Rulemaking for the California State 
Implementation Plan (SIP), San Joaquin Valley Unified Air Pollution 
Control District's Rule 4905, Natural Gas-Fired, Fan-Type Central 
Furnaces,'' October 5, 2015, n. 8.
    \225\ 2018 PM2.5 Plan, Appendix C, p. C-290.
---------------------------------------------------------------------------

    Second, the SJV PM2.5 Plan lists Rule 4203 
(``Particulate Matter Emissions from Incineration of Combustible 
Refuse'') as a baseline measure. This rule has not been approved into 
the California SIP.\226\ Appendix C of the 2018 PM2.5 Plan 
indicates, however, that the emissions inventory for incineration of 
combustible refuse is 0.00 tpd of NOX and 0.00 tpd direct 
PM2.5 from 2013 through 2023.\227\ Thus, although the 
District included this rule as a baseline measure, there are no 
meaningful

[[Page 45299]]

reductions associated with this rule that would affect the attainment 
demonstration in the SJV PM2.5 Plan.
---------------------------------------------------------------------------

    \226\ The EPA does not have any pending SIP submission for Rule 
4203.
    \227\ 2018 PM2.5 Plan, Appendix C, p. C-46.
---------------------------------------------------------------------------

    In sum, although Table 4-1 of the 15 [mu]g/m\3\ SIP Revision 
identifies two baseline measures that are not creditable for SIP 
purposes at this time, we conclude that the total emissions reductions 
attributed to these two measures in the future baseline inventories 
would not materially affect the attainment demonstration in the Plan.
ii. Additional Measures and CARB Commitment
    In addition to baseline control measures, the SJV PM2.5 
Plan identifies several additional control measures that will 
contribute to expeditious attainment of the 1997 annual 
PM2.5 NAAQS. These measures include three regulatory 
measures adopted by CARB or the District following development of the 
2018 PM2.5 Plan, and a commitment by CARB to adopt and 
implement an additional regulatory measure to meet an enforceable 
commitment. The three regulatory measures adopted following development 
of the 2018 PM2.5 Plan include CARB's ``Lower Opacity Limits 
for Heavy-Duty Vehicles'' regulation,\228\ CARB's ``Amended Warranty 
Requirements for Heavy-Duty Vehicles'' regulation,\229\ and the 
District's 2019 amendments to Rule 4901 (``Wood Burning Fireplaces and 
Wood Burning Heaters'').\230\ In addition to these three adopted 
measures, the 15 [mu]g/m\3\ SIP Revision includes a commitment by CARB 
to achieve aggregate emissions reductions of 3.0 tpd of NOX 
and 0.04 tpd of direct PM2.5 (referred to as an ``aggregate 
tonnage commitment'') through adoption of CARB's ``Heavy-Duty Vehicle 
Inspection and Maintenance Program'' (``Heavy-Duty I/M'') (referred to 
as a ``control measure commitment'') and/or substitute measures.\231\ 
Table 5 summarizes the NOX and direct PM2.5 
emissions reductions associated with these additional measures in the 
15 [mu]g/m\3\ SIP Revision.
---------------------------------------------------------------------------

    \228\ Initially adopted via CARB Resolution 18-20 (May 25, 
2018). CARB Resolution 18-20 was repealed on July 26, 2018 via CARB 
Resolution 18-28, which included a modified version of the 
regulation to address public comments. Per direction from CARB 
Resolution 18-28, the regulation was adopted via Executive Order 
R19-001 (March 12, 2019).
    \229\ CARB Resolution 18-24, June 28, 2018.
    \230\ SJVUAPCD Resolution 19-06-22, June 20, 2019.
    \231\ CARB Resolution 21-21, September 23, 2021, p. 6; and 
August 2021 Staff Report, pp. 4-5.

      Table 5--Additional NOX and Direct PM2.5 Emission Reductions
------------------------------------------------------------------------
                                          NOX  emissions       PM2.5
   Additional measures relied upon for     reductions in     emissions
 attainment  (beyond baseline measures)     2023  (tpd)    reductions in
                                                            2023  (tpd)
------------------------------------------------------------------------
District's 2019 Revisions to Rule 4901..  ..............             0.2
CARB's Lower Opacity Limits for Heavy-    ..............            0.09
 Duty Vehicles..........................
CARB's Warranty Requirements for Heavy-             0.01  ..............
 Duty Vehicles..........................
CARB's Heavy-Duty I/M...................  ..............            0.04
------------------------------------------------------------------------
Source: 15 [mu]g/m\3\ SIP Revision, Appendix K, Table 32.

    Following CARB's submission of the 15 [mu]g/m\3\ SIP Revision, on 
October 20, 2021, CARB and the District submitted to the EPA the 
``Progress Report and Technical Submittal for the 2012 PM2.5 
Standard San Joaquin Valley'' (2021 Progress Report).\232\ The 2021 
Progress Report describes the State's progress to date in developing 
and adopting the additional measures identified in their control 
measure commitments in the 2018 PM2.5 Plan for purpose of 
attaining the 2012 annual PM2.5 NAAQS.\233\ These measures 
include the additional measures identified in the 15 [mu]g/m\3\ SIP 
Revision (i.e., the measures in Table 5 of this proposal). The 2021 
Progress Report provides status updates on the substance of each 
measure and the timing of board consideration for both adopted and 
remaining control measure commitments. The report also provides a side-
by-side comparison of the original emission reduction estimates in the 
2018 PM2.5 Plan for each control measure commitment and 
updated emission reduction estimates for each measure based on 
technical analyses for adopted measures and draft measures and/or 
documentation in development for forthcoming regulations.\234\ Although 
the purpose of the 2021 Progress Report was to provide an update on the 
progress that CARB and the District have made towards implementing the 
attainment strategy for the 2012 annual PM2.5 NAAQS, some of 
the information provided in the report is relevant to the State's 
progress towards attaining the 1997 annual PM2.5 NAAQS, as 
discussed below.
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    \232\ ``Progress Report and Technical Submittal for the 2012 
PM2.5 Standard San Joaquin Valley,'' October 19, 2021. 
Transmitted to the EPA by letter dated October 20, 2021, from 
Richard W. Corey, Executive Officer, CARB, to Deborah Jordan, Acting 
Regional Administrator, EPA Region IX. See sections of 2021 Progress 
Report entitled ``Progress in Implementing District Measures'' and 
``Progress in Implementing CARB Measures.''
    \233\ As discussed in fn. 28 of this document, the Serious area 
plan for the 2012 PM2.5 NAAQS has since been withdrawn by 
the State.
    \234\ 2021 Progress Report, tables 2 and 3.
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    First, on July 22, 2020, the EPA published its final approval of 
the District's 2019 amendment to Rule 4901 \235\ and concurrently 
credited this measure with annual average emission reductions of 0.2 
tpd direct PM2.5 towards the District's PM2.5 
tonnage commitment in the 2018 PM2.5 Plan for 2024.\236\ As 
described in the EPA's March 27, 2020 proposed rule, this amount of SIP 
credit corresponded to a 75 percent compliance rate (referred to as a 
``rule effectiveness rate''), consistent with EPA guidance on wood 
burning curtailment programs,\237\ rather than a higher 100 percent 
rule effectiveness rate used in the District's original 
calculations.\238\ In the 2021 Progress Report, the State notes this 
conclusion in the EPA's July 22, 2020 final rule approving this measure 
into the SIP and now estimates emission reductions of 0.2 tpd direct 
PM2.5 from this measure, both in the report \239\ and in the 
15 [mu]g/m\3\ SIP Revision.\240\ Consistent with the EPA's July 22, 
2020 final rule, we propose to credit this measure with annual average 
emission reductions of 0.2 tpd direct PM2.5 for purposes of 
attaining the 1997 annual PM2.5 NAAQS by December 31, 2023.
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    \235\ 85 FR 44206.
    \236\ 85 FR 44192, 44204.
    \237\ Strategies for Reducing Wood Smoke, EPA-456/B-13-01, March 
2013, p. 42.
    \238\ 85 FR 17382, 17415.
    \239\ 2021 Progress Report, p. 7 and Table 3.
    \240\ 15 [mu]g/m\3\ SIP Revision, Appendix K, Table 32.
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    Second, in 2018, CARB adopted the Lower Opacity Limits for Heavy-
Duty Vehicles regulation as a revision to the

[[Page 45300]]

Heavy-Duty Vehicle Inspection Program (HDVIP) and Periodic Smoke 
Inspection Program (PSIP). CARB submitted the measure to the EPA on 
February 13, 2020, and on May 10, 2022, the EPA approved the measure 
into the California SIP.\241\ CARB initially estimated in its staff 
report for the measure that it would achieve 1,170 tons of PM emissions 
benefits from the heavy-duty trucking transportation sector from 2019 
to 2025.\242\ In the 15 [mu]g/m\3\ SIP Revision, CARB estimates that 
the Lower Opacity Limits for Heavy-Duty Vehicles regulation will 
achieve 0.09 tpd direct PM2.5 reductions in 2023. CARB later 
clarified via email that it derived this estimate using EMFAC2017 and 
that if it instead used EMFAC2014, consistent with the 15 [mu]g/m\3\ 
SIP Revision, the estimated reductions are 0.01 tpd of direct 
PM2.5 by 2023.\243\ However, CARB has not yet provided its 
analysis of the basis for this emissions reduction estimate for the San 
Joaquin Valley. Therefore, the EPA is not proposing at this time to 
credit this measure with any particular amount of emissions reductions 
toward attainment of the 1997 annual PM2.5 NAAQS in the San 
Joaquin Valley. While the Plan indicates that the State attributed 
annual average emission reductions of 0.09 tpd of PM2.5 
reductions between 2013 and 2023 to the Lower Opacity Limits for Heavy-
Duty Vehicles regulation, these emissions reductions would not 
materially affect the attainment demonstration for the 1997 annual 
PM2.5 NAAQS in the SJV PM2.5 Plan.
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    \241\ 87 FR 27949.
    \242\ CARB, ``Proposed Amendments to the Heavy-Duty Vehicle 
Inspection Program and Periodic Smoke Inspection Program, Staff 
Report: Initial Statement of Reasons,'' release date April 3, 2018, 
p. 15. See also, EPA Region IX, ``Technical Support Document for 
EPA's Rulemaking for the California State Implementation Plan, 
California Air Resources Board--Title 13, Division 3, Chapter 3.5; 
Opacity Testing of Heavy-Duty Diesel Vehicles,'' July 2021, p. 4.
    \243\ Email dated March 3, 2022, from Laura Carr, CARB, to 
Ashley Graham, EPA Region IX, Subject: ``Lower Opacity regulation 
reductions.'' This email is in the docket for this proposed action,
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    Third, CARB adopted the Amended Warranty Requirements for Heavy-
Duty Vehicles regulation on June 28, 2018 (``2018 HD Warranty 
Amendments''). CARB estimates that the measure will achieve 0.01 tpd of 
NOX emissions reductions in 2023. By letter dated October 
22, 2021, CARB submitted a request that the EPA determine that the 2018 
HD Warranty Amendments are within the scope of the previously-granted 
waiver for California's emissions standards and associated test 
procedures for 2007 and subsequent model year heavy-duty diesel vehicle 
engines. Alternatively, CARB requested that the EPA grant California a 
new waiver of preemption for the 2018 HD Warranty Amendments. The EPA 
published a notice of opportunity for public hearing and comment 
concerning CARB's request on June 13, 2022, and the EPA held a public 
hearing on June 29, 2022.\244\ On April 5, 2023, the EPA determined 
that the 2018 HD Warranty Amendments meet the criteria for a new waiver 
under section 209(b) of the CAA.\245\ However, because the measure has 
not been approved into the California SIP, the EPA is not proposing at 
this time to credit this measure with any particular amount of 
emissions reductions toward attainment of the 1997 annual 
PM2.5 NAAQS in the San Joaquin Valley. Given the relatively 
small quantity of reductions from this measure, these emissions 
reductions would not materially affect the attainment demonstration for 
the 1997 annual PM2.5 NAAQS in the SJV PM2.5 
Plan.
---------------------------------------------------------------------------

    \244\ 87 FR 35760.
    \245\ 88 FR 20688.
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    Finally, the 15 [mu]g/m\3\ SIP Revision includes an aggregate 
emissions reduction commitment by CARB to achieve reductions of 3.0 tpd 
of NOX and 0.04 tpd of direct PM2.5 through 
adoption of CARB's Heavy-Duty I/M program and/or substitute 
measures.\246\ These reductions amount to 1.8 percent and 0.9 percent 
of the total NOX and direct PM2.5 reductions, 
respectively, needed to attain the 1997 annual PM2.5 NAAQS. 
CARB adopted the Heavy-Duty I/M measure on December 9, 2021, fulfilling 
CARB's control measure commitment in the 15 [mu]g/m\3\ SIP Revision. 
Implementation of the program began on January 1, 2023. On December 14, 
2022, CARB submitted the measure to the EPA as a revision to the 
California SIP.\247\ The EPA is not proposing to credit the emission 
reductions from the Heavy-Duty I/M program towards the aggregate 
tonnage commitment at this time. The EPA will take such action in a 
separate future rulemaking.
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    \246\ CARB Resolution 21-21, pp. 4-5.
    \247\ Letter dated December 7, 2022, from Steven S. Cliff, 
Ph.D., Executive Officer, to Martha Guzman, Regional Administrator, 
EPA Region IX, with enclosures.
---------------------------------------------------------------------------

    In addition to the baseline and additional measures discussed 
above, CARB notes in its August 2021 Staff Report accompanying the 15 
[micro]g/m\3\ SIP Revision that two additional measures are expected to 
provide for more emissions reductions by the 2023 attainment year for 
the 1997 annual PM2.5 NAAQS.\248\ While the EPA is not 
proposing to credit either of these measures at this time towards the 
aggregate tonnage commitment for the 1997 annual PM2.5 
NAAQS, we agree with the State that they will further reduce ambient 
PM2.5 levels and exposure to PM2.5 pollution for 
communities in the San Joaquin Valley.
---------------------------------------------------------------------------

    \248\ August 2021 Staff Report, pp. 3-4.
---------------------------------------------------------------------------

    The first measure is the Accelerated Turnover of Agricultural 
Equipment Incentive Projects (``Agricultural Equipment Incentive 
Measure''), which includes commitments by CARB to monitor, assess, and 
report on emission reductions, and to achieve emission reductions of 
5.1 tpd NOX and 0.3 tpd direct PM2.5 from the 
2025 baseline inventory in the 2018 PM2.5 Plan by December 
31, 2024.\249\ The State asserts in the August 2021 Staff Report that a 
large portion of those emissions reductions will be achieved by 
2023.\250\ The EPA finalized a partial approval of this measure on 
December 16, 2021, wherein the EPA credited 4.83 tpd NOX and 
0.24 tpd direct PM2.5 towards CARB's tonnage commitments for 
2024 (for attaining the 2006 24-hour PM2.5 NAAQS), and 
calculated 4.46 tpd NOX and 0.26 tpd direct PM2.5 
for 2025 (for attaining the 2012 annual PM2.5 NAAQS).\251\
---------------------------------------------------------------------------

    \249\ EPA Region IX ``Technical Support Document for EPA's 
Rulemaking for the California State Implementation Plan California 
Air Resources Board Resolution 19-26 San Joaquin Valley Agricultural 
Equipment Incentive Measure,'' February 2020, pp. 4-5, 24-25, and 
31.
    \250\ CARB's August 2021 Staff Report, p. 3.
    \251\ 86 FR 73106 (December 27, 2021). The EPA deferred action 
on the NRCS portion of the Agricultural Equipment Incentive Measure.
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    The second measure is the Agricultural Burning Phase-out Measure, 
which for purposes of state law, was adopted by the District on June 
17, 2021,\252\ and concurred on by CARB on June 18, 2021,\253\ and 
later adopted by the District on November 18, 2021, as a revision to 
the California SIP.\254\ Previously, through Rule 4103 (``Open 
Burning''), as amended April 15, 2010, the District restricted the type 
of materials that may be burned and established other conditions and 
procedures for open burning in conjunction with the District's Smoke 
Management Program.\255\ The EPA

[[Page 45301]]

approved Rule 4103 and the associated table of the restrictions on open 
burning by crop category into the California SIP on January 4, 
2012.\256\ The District identifies Rule 4103 as a baseline measure in 
the 2018 PM2.5 Plan.\257\ The Agricultural Burning Phase-out 
Measure, in turn, includes a schedule to phase-out (i.e., introduce 
prohibitions of) agricultural burning for additional crop categories or 
materials accounting for a vast majority of the tonnage of agricultural 
waste in phases starting January 1, 2022, and becoming fully 
implemented by January 1, 2025.\258\ Thus, the State asserts that the 
measure will provide for additional reductions in 2023 not accounted 
for in the attainment demonstration for the in the 15 [micro]g/m\3\ SIP 
Revision for 1997 annual PM2.5 NAAQS.\259\ The EPA approved 
the Agricultural Burning Phase-out Measure into the California SIP on 
June 16, 2022.\260\
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    \252\ SJVUAPCD Resolution 21-06-12, June 17, 2021.
    \253\ Letter dated June 18, 2021, from Richard W. Corey, 
Executive Officer, CARB, to Samir Sheikh, Executive Director, 
SJVUAPCD.
    \254\ SJVUAPCD Resolution 21-11-7, November 18, 2021. See also, 
Letter dated October 20, 2021, from Richard W. Corey, Executive 
Officer, CARB, to Deborah Jordan, Acting Regional Administrator, EPA 
Region IX.
    \255\ SJVUAPCD Rule 4103, as amended April 15, 2010.
    \256\ 77 FR 214 (January 4, 2012). The table of open burning 
restrictions by crop category is codified at 40 CFR 
52.220(c)(388)(i)(B)(3) Table 9-1, Revised Proposed Staff Report and 
Recommendations on Agricultural Burning, approved by the District on 
May 20, 2010.
    \257\ 2018 PM2.5 Plan, Chapter 4, tables 4-2 and 4-3, 
and Appendix C.
    \258\ 2021 Supplemental Report and Recommendations, Table 2-1 
(``Accelerated Reductions by Crop Category'').
    \259\ CARB's August 2021 Staff Report, pp. 3-4.
    \260\ 87 FR 36222.
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iii. Three Factor Test for Enforceable Commitments
    The EPA interprets the CAA to allow for approval of enforceable 
commitments that are limited in scope where circumstances exist that 
warrant the use of such commitments in place of adopted and submitted 
measures.\261\ Specifically, CAA section 110(a)(2)(A) provides that 
each SIP ``shall include enforceable emission limitations and other 
control measures, means or techniques. . .as well as schedules and 
timetables for compliance, as may be necessary or appropriate to meet 
the applicable requirements of [the Act].'' Section 172(c)(6) of the 
Act, which applies to nonattainment SIPs, is virtually identical to 
section 110(a)(2)(A). The language in these sections of the CAA is 
broad, allowing a SIP to contain any ``means or techniques'' that the 
EPA determines are ``necessary or appropriate'' to meet CAA 
requirements, such that the area will attain as expeditiously as 
practicable, but no later than the designated date. Furthermore, the 
express allowance for ``schedules and timetables'' demonstrates that 
Congress understood that all required controls might not have to be in 
place before a SIP could be fully approved.
---------------------------------------------------------------------------

    \261\ Commitments approved by the EPA under CAA section 
110(k)(3) are enforceable by the EPA and citizens under CAA sections 
113 and 304, respectively. In the past, the EPA has approved 
enforceable commitments and courts have enforced these actions 
against states that failed to comply with those commitments. See, 
e.g., American Lung Ass'n of N.J. v. Kean, 670 F. Supp. 1285 (D.N.J. 
1987), aff'd, 871 F.2d 319 (3rd Cir. 1989); NRDC v. N.Y. State Dept. 
of Env. Cons., 668 F. Supp. 848 (S.D.N.Y. 1987); Citizens for a 
Better Env't v. Deukmejian, 731 F. Supp. 1448, recon. granted in 
par, 746 F. Supp. 976 (N.D. Cal. 1990); Coalition for Clean Air v. 
South Coast Air Quality Mgt. Dist., No. CV 97-6916-HLH, (C.D. Cal. 
Aug. 27, 1999). Further, if a state fails to meet its commitments, 
the EPA could make a finding of failure to implement the SIP under 
CAA section 179(a), which starts an 18-month period for the State to 
correct the non-implementation before mandatory sanctions are 
imposed.
---------------------------------------------------------------------------

    Once the EPA determines that circumstances warrant consideration of 
an enforceable commitment to satisfy a CAA requirement, it considers 
three factors in determining whether to approve the enforceable 
commitment: (1) does the commitment address a limited portion of the 
CAA requirement; (2) is the state capable of fulfilling its commitment; 
and (3) is the commitment for a reasonable and appropriate period of 
time.\262\
---------------------------------------------------------------------------

    \262\ The Fifth Circuit Court of Appeals upheld the EPA's 
interpretation of CAA sections 110(a)(2)(A) and 172(c)(6) and the 
Agency's use and application of the three factor test in approving 
enforceable commitments in the 1-hour ozone SIP for Houston-
Galveston. BCCA Appeal Group v. EPA, 355 F.3d 817 (5th Cir. 2003). 
More recently, the Ninth Circuit Court of Appeals upheld the EPA's 
approval of enforceable commitments in ozone and PM2.5 
SIPs for the San Joaquin Valley, based on the same three factor 
test. Committee for a Better Arvin v. EPA, 786 F.3d 1169 (9th Cir. 
2015). But see, Medical Advocates for Healthy Air v. EPA, Case No. 
20-72780, (9th Cir., Apr. 13, 2022) (finding that the EPA did not 
adequately show the State was capable of fulfilling its commitment 
with respect to incentive-based control measure commitments).
---------------------------------------------------------------------------

    With respect to the SJV PM2.5 Plan, circumstances 
warrant the consideration of enforceable commitments as part of the 
attainment demonstration for this area. As discussed in Section 
IV.C.2.a.i of this proposed rule, the majority of the emissions 
reductions needed to demonstrate attainment and RFP in the San Joaquin 
Valley are achieved by rules and regulations adopted prior to the 
State's development of the SJV PM2.5 Plan, i.e., baseline 
measures. As a result of these already-adopted CARB and District 
measures, most air pollution sources in the San Joaquin Valley were 
already subject to stringent rules prior to the development of the SJV 
PM2.5 Plan, leaving fewer and more technologically 
challenging opportunities to reduce emissions. Despite these 
significant emission reductions, as shown in Table 4 of this proposed 
rule, the State needs to reduce NOX and direct 
PM2.5 emission levels by a total of 52.5 percent and 7.2 
percent, respectively, from 2013 base year levels in order to attain 
the 1997 annual PM2.5 NAAQS in the San Joaquin Valley.
    As part of CARBs control measure commitment in the 15 [micro]g/m\3\ 
SIP Revision, it identifies the control measure (i.e., Heavy-Duty I/M) 
that it expects to achieve the additional emissions reductions needed 
for attainment. The timeline needed to develop, adopt, and implement 
the measure extended beyond the timeline for Plan adoption, with board 
consideration scheduled for December 2021 at the time the Plan was 
developed.\263\ As discussed in Section IV.C.2.a.ii of this document, 
CARB adopted the Heavy-Duty I/M measure on December 9, 2021, fulfilling 
CARB's control measure commitment per the schedule in the Plan. Given 
these circumstances, we conclude that reliance on enforceable 
commitments in the SJV PM2.5 Plan is warranted. Therefore, 
we have considered the three factors the EPA uses to determine whether 
the use of enforceable commitments in lieu of adopted measures 
satisfies CAA planning requirements.
---------------------------------------------------------------------------

    \263\ August 2021 Staff Report, p. 4.
---------------------------------------------------------------------------

(1) The Commitment Represents a Limited Portion of Required Reductions
    For the first factor, we look to see if the commitment addresses a 
limited portion of a statutory requirement, such as the amount of 
emissions reductions needed to attain the NAAQS in a nonattainment 
area. As discussed in Section IV.C.2.a.i of this proposed rule, most of 
the total emission reductions needed to attain the 1997 annual 
PM2.5 NAAQS in the San Joaquin Valley by the end of 2023 
will be achieved through implementation of baseline measures and 
additional measures for which the EPA has finalized approval, leaving 
1.8 percent (3 tpd) of the necessary NOX reductions and 0.9 
percent (0.04 tpd) of the necessary direct PM2.5 reductions 
as aggregate tonnage commitments.
    Given the nature of the PM2.5 challenge in the San 
Joaquin Valley, the significant reductions in NOX and direct 
PM2.5 emission levels achieved through implementation of 
baseline measures over the past several decades, and the difficulty of 
identifying additional control measures that are feasible for 
implementation in the area, we consider it reasonable for CARB and the 
District to seek additional time to develop and adopt the last 
increment of emission reductions necessary for attainment by 2023. 
Therefore, we conclude that the

[[Page 45302]]

emission reductions remaining as enforceable commitments in the SJV 
PM2.5 Plan represent a limited portion of the total 
emissions reductions needed to demonstrate attainment of the 1997 
annual PM2.5 NAAQS by December 31, 2023.
(2) The State Is Capable of Fulfilling Its Commitment
    For the second factor, we consider whether the State is capable of 
fulfilling its commitments. As discussed in Section IV.C.2.a.ii of this 
document, CARB has already adopted the regulatory measure (i.e., Heavy-
Duty I/M) it committed to in the SJV PM2.5 Plan for the 1997 
annual PM2.5 NAAQS. The aggregate tonnage commitments 
associated with this measure are 3 tpd of NOX and 0.04 tpd 
of direct PM2.5 in 2023, less than 2 percent of the 
NOX and direct PM2.5 emissions reductions needed 
for attainment by December 31, 2023.\264\
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    \264\ Unlike the aggregate commitments at issue in the Medical 
Advocates case, which relied in-part on incentive-based control 
measure commitments, the aggregate commitment the EPA is proposing 
to approve in this action consists solely of a regulatory measure 
that has already been adopted and submitted by the State and for 
which implementation began on January 1, 2023.
---------------------------------------------------------------------------

    Given CARB's progress in adopting the Heavy-Duty I/M measure it 
committed to in the 15 [micro]g/m\3\ SIP Revision per the schedule in 
the Plan and its continuing efforts to develop additional control 
measures to further reduce NOX and PM2.5 
emissions in the San Joaquin Valley, we propose that CARB is capable of 
fulfilling the remaining increment of NOX emission 
reductions necessary to attain the 1997 annual PM2.5 NAAQS 
in the San Joaquin Valley by December 31, 2023.
    More broadly, we note that CARB will have to submit to the EPA, for 
SIP approval, any control measure that it intends to rely on to satisfy 
the aggregate tonnage commitments in the Plan. Furthermore, if CARB 
intends to substitute reductions in one pollutant to achieve a tonnage 
commitment concerning a different pollutant (e.g., substituting direct 
PM2.5 reductions to satisfy a NOX reduction 
commitment), it must include an appropriate inter-pollutant trading 
(IPT) ratio and the technical basis for such ratio. The EPA will review 
any such IPT ratio and its bases before approving or disapproving the 
measure.
(3) The Commitment Is for a Reasonable and Appropriate Timeframe
    For the third factor, we consider whether the commitment is for a 
reasonable and appropriate period of time. The SJV PM2.5 
Plan includes specific rule adoption and implementation schedules for 
the Heavy-Duty I/M measure to meet CARB's commitment to reduce 
emissions to the levels needed to attain the 1997 annual 
PM2.5 NAAQS in the San Joaquin Valley by 2023. CARB has 
already met its control measure commitment through its December 2021 
adoption of the Heavy-Duty I/M measure and implementation ahead of the 
December 31, 2023 projected attainment date. We consider that these 
schedules provide a reasonable and appropriate amount of time for CARB 
to achieve the remaining emission reductions necessary to attain the 
1997 annual PM2.5 NAAQS in the San Joaquin Valley by 
December 31, 2023. We therefore propose to conclude that the third 
factor is satisfied.
b. Best Available Control Measures
    We are evaluating the State's BACM demonstration for the 1997 
annual PM2.5 NAAQS against the section 189(b)(1)(B) Serious 
area plan BACM requirement, and the section 189(d) plan requirement to 
address all Serious area plan requirements that the State has not 
already met. Because we have already found that the State failed to 
attain the 1997 annual PM2.5 NAAQS in the San Joaquin Valley 
area by the Serious area attainment date, and because we have not 
previously found that the state has met the BACM requirement for 
purposes of the 1997 annual PM2.5 NAAQS, we are evaluating 
the State's submission against the Serious area BACM requirement in 
light of the section 189(d) control plan timeline.
i. Summary of the State's Submission
    The State's BACM demonstration is presented in Appendix C 
(``Stationary Source Controls'') of the 2018 PM2.5 Plan and 
Appendix D (``Mobile Source Control Measure Analyses'') of the 15 
[micro]g/m\3\ SIP Revision.\265\ The State also provided additional 
information regarding building heating appliances, including 
residential natural gas-fired water heaters and furnaces, in a document 
titled ``Building Electrification Technical Supplement for the 1997 
Annual PM2.5 NAAQS'' (``March 2023 Building Heating 
Supplement''), submitted to the EPA on March 30, 2023.\266\
---------------------------------------------------------------------------

    \265\ Appendices C and D also present an MSM analysis for the 
purposes of meeting a precondition for an extension of the Serious 
area attainment date under CAA section 188(e) for the 2006 
PM2.5 NAAQS. The San Joaquin Valley area is not subject 
to the MSM requirement for the 1997 annual PM2.5 NAAQS. 
Thus, the EPA is evaluating the Plan's control strategy for 
implementation of BACM and BACT only.
    \266\ Letter dated March 29, 2023, from Steven S. Cliff, 
Executive Officer, CARB, to Martha Guzman, Regional Administrator, 
EPA Region 9, with enclosures. This letter is in the docket for this 
proposed action.
---------------------------------------------------------------------------

    As discussed in Section IV.A of this proposed rule, Appendix B 
(``Emissions Inventory'') of the 2018 PM2.5 Plan contains 
the planning inventories for direct PM2.5 and all 
PM2.5 precursors (NOX, SOX, VOC, and 
ammonia) for the San Joaquin Valley nonattainment area together with 
documentation to support these inventories. Each inventory includes 
emissions from stationary, area, on-road, and non-road emissions 
sources, and the State specifically identifies the condensable 
component of direct PM2.5 for relevant stationary source and 
area source categories. As discussed in Section IV.B of this proposed 
rule, the State concluded that the Plan should control emissions of 
PM2.5 and NOX to reach attainment. Accordingly, 
the BACM and BACT evaluation in the Plan addresses potential controls 
for sources of those pollutants.
Stationary and Area Sources
    For stationary and area sources, the District identifies the 
sources of direct PM2.5 and NOX in the San 
Joaquin Valley that are subject to District emissions control measures 
and provides its evaluation of these regulations for compliance with 
BACM requirements in Appendix C of the 2018 PM2.5 Plan. As 
part of its process for identifying candidate BACM and considering the 
technical and economic feasibility of additional control measures, the 
District reviewed the EPA's guidance documents on BACM, additional 
guidance documents on control measures for direct PM2.5 and 
NOX emissions sources, and control measures implemented in 
other ozone and PM2.5 nonattainment areas in California and 
other states.\267\ Based on these analyses, the District concludes that 
all best available control measures for stationary and area sources are 
in place in the San Joaquin Valley for NOX and directly 
emitted PM2.5 for purposes of meeting the BACM/BACT 
requirement for the 1997 annual PM2.5 NAAQS. We provide an 
evaluation of many of the District's control measures for stationary 
sources and area sources in Section IV of the EPA's 1997 Annual 
PM2.5 TSD together with recommendations for possible future 
improvements to these rules.
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    \267\ 15 [micro]g/m\3\ SIP Revision, Chapter 4, Section 4.3.1.

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[[Page 45303]]

    As noted earlier, the State provided additional information to the 
EPA to support its BACM analysis for building heating appliances in its 
March 2023 Building Electrification Supplement.\268\ We provide a 
summary of the State's BACM analysis for building heating appliances in 
the paragraphs that follow.
---------------------------------------------------------------------------

    \268\ Letter dated March 29, 2023, from Steven S. Cliff, 
Executive Officer, CARB, to Martha Guzman, Regional Administrator, 
EPA Region 9, with enclosures.
---------------------------------------------------------------------------

    The State provides a summary of its existing rules governing 
building heating appliances, including Rule 4902 (``Residential Water 
Heaters'') and Rule 4905 (``Natural Gas-Fired, Fan-Type Central 
Furnaces''), in Appendix C of the 2018 PM2.5 Plan.\269\ The 
rules are point of sale rules that limit the types of water heaters and 
furnaces that may be sold in the San Joaquin Valley.\270\ The District 
also provides comparisons of its rules with rules in other California 
air districts.\271\ Based on the District's analysis at that time, it 
determined that it was implementing the most stringent requirements 
feasible for such building heating appliances.
---------------------------------------------------------------------------

    \269\ 2018 PM2.5 Plan, Appendix C, sections C.20 and 
C.21.
    \270\ SJVUAPCD Rule 4902 (``Residential Water Heaters''), 
amended March 19, 2009, and SJVUAPCD Rule 4905 (``Natural Gas-Fired, 
Fan-Type Central Furnaces''), amended January 22, 2015.
    \271\ 2018 PM2.5 Plan, Appendix C, sections C.20 and 
C.21.
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    The EPA has previously provided our evaluation of the District's 
BACM demonstration in the 2018 PM2.5 Plan for stationary and 
area sources in general, and several source categories in more detail, 
for purposes of other PM2.5 NAAQS in three documents: (1) 
the EPA's ``Technical Support Document, EPA Evaluation of BACM/MSM, San 
Joaquin Valley PM2.5 Plan for the 2006 PM2.5 
NAAQS,'' February 2020 (``EPA's BACM/MSM TSD''); (2) the EPA's 
``Response to Comments Document for the EPA's Final Action on the San 
Joaquin Valley Serious Area Plan for the 2006 PM2.5 NAAQS,'' 
June 2020 (``EPA's 2020 Response to Comments''); and (3) Section II of 
the EPA's ``Technical Support Document, San Joaquin Valley 
PM2.5 Plan for the 1997 24-hour PM2.5 NAAQS,'' 
August 2021 (``EPA's 1997 24-hour PM2.5 TSD''). In 
particular, the EPA's 2020 Response to Comments presented our 
evaluation of the District's BACM demonstration for residential water 
heaters and residential and commercial, natural gas-fired, fan-type 
central furnaces.\272\ At that time we found that the requirements for 
residential fuel combustion sources covered by Rules 4902 and 4905 
represented BACM.\273\ In addition, the EPA concluded that setting a 
zero-NOX standard for heating appliances in new buildings 
reasonably requires additional consideration and analysis of 
technological and economic feasibility by the District because, per the 
2018 PM2.5 Plan, the most common types of residential water 
heaters and furnaces are those that use natural gas as fuel.
---------------------------------------------------------------------------

    \272\ EPA's 2020 Response to Comments, pp. 142-148, Comment 6.O 
and Response 6.O.
    \273\ Id. at 146-147.
---------------------------------------------------------------------------

    We also noted in the EPA's 2020 Response to Comments that the 
building codes referenced by commenters at that time appeared to be 
green building code ordinances that restrict or prohibit installation 
of natural gas or propane appliances in new construction.\274\ Such 
ordinances, most of which appeared to have been adopted in late 2019 
and early 2020, fell within a category known as ``reach codes,'' which 
are city and county building code standards for energy efficiency that 
exceed California's statewide standards. We stated that California law 
requires local governments to submit proposed ordinances to the 
California Energy Commission for a determination that they will be both 
cost effective and more energy efficient than statewide standards, and 
that compliance with this procedure is necessary for such measures to 
be enforceable.\275\ We also noted that ordinances adopted by city 
councils and county officials are legally distinct from measures 
adopted by the governing boards of the respective air districts and 
that it did not appear at the time that California air districts had 
adopted similar restrictions.
---------------------------------------------------------------------------

    \274\ Id. at 147-148.
    \275\ California 2019 Building Energy Standards, at California 
Code of Regulations (CCR), title 24, part 1, article 1, sec. 10-106 
(``Locally Adopted Energy Standards''); see also https://ww2.energy.ca.gov/title24/2016standards/ordinances.
---------------------------------------------------------------------------

    Since the time of the EPA's actions on the San Joaquin Valley plans 
for the 2006 24-hour and 1997 24-hour PM2.5 standards (i.e., 
2020-2021), additional jurisdictions have adopted natural gas bans, 
appliance standards, and other strategies to reduce emissions from 
building heating devices.\276\ Furthermore, CARB and the Bay Area AQMD 
are moving forward in developing measures to set zero-emission 
standards for space heaters and water heaters. Given these factors, the 
State has supplemented its evaluation of the feasibility of 
strengthening its rules for building heating sources for purposes of 
the EPA's evaluation of the SJV PM2.5 Plan for the 1997 
annual PM2.5 NAAQS.\277\
---------------------------------------------------------------------------

    \276\ We note, for awareness only, that the City of Berkeley 
introduced an ordinance in 2019 prohibiting the installation of 
natural gas infrastructure in most new buildings. In April 2023, the 
Ninth Circuit Court of Appeals reversed and remanded the prior 
district court's rule that upheld the ordinance on the grounds that 
the federal Energy Policy and Conservation Act expressly preempted 
the local ordinance's regulation of ``energy use'' of a product 
covered by the statute. California Restaurant Association v. City of 
Berkeley, No. 21-16278 (9th Cir. 2023).
    \277\ The EPA's evaluation of BACM for NOX emissions 
from building heating appliances in its proposed rule on the State's 
Serious area plan for the 2012 annual PM2.5 NAAQS was the 
subject of adverse comments. (86 FR 74310, December 29, 2021); and 
comment letter dated and received January 28, 2022, from Brent 
Newell, Public Justice, et al., to Rory Mays, EPA, including 
Exhibits 1 through 47. The EPA re-proposed action on portions of 
that Serious area plan, including BACM for building heating 
appliances based on the record available at the time. (87 FR 60494, 
October 5, 2022). However, the State withdrew that original Serious 
area plan on October 27, 2022, and has since supplemented its 
analysis of BACM for this source category, as described herein.
---------------------------------------------------------------------------

    The March 2023 Building Electrification Supplement includes 
analyses from both CARB and the District regarding the stringency of 
the District's current rules, recent efforts across the State of 
California to further reduce emissions from building heating 
appliances, and information supporting the State's assertion that it is 
infeasible, and therefore not required for BACM, to implement a zero-
emission regulation for building heating appliances within the 
timeframe of the Plan for the 1997 annual PM2.5 NAAQS.
    First, the District asserts that its Rules 4902 (``Residential 
Water Heaters''), 4308 (``Boilers, Steam Generators, and Process 
Heaters--0.075 MMBtu/HR to Less Than 2.0 MMBtu/HR''), and 4905 
(``Natural Gas-Fired, Fan-Type Central Furnaces'') include the most 
stringent requirements currently being implemented for water and space 
heaters in the nation and are the most stringent measures feasible for 
implementation in the San Joaquin Valley as of March 2023.\278\ 
Specifically, the District notes that its NOX limits of 10 
and 14 nanograms of NOX per joule of useful heat (ng/J) for 
water and space heaters, respectively, are the same as those 
implemented by the South Coast AQMD and are the most stringent in the 
country.\279\ The District also points to its efforts to reduce 
emissions from home heating through its Fireplace and Woodstove Change-
Out incentive program, which offers support for purchasing and 
installing cleaner space heating appliances.\280\ The District notes

[[Page 45304]]

that the program has helped replace over 21,000 wood burning appliances 
with natural gas inserts, stoves, and fireplaces and that recent 
changes to the program are providing larger incentives for electric 
space heating and cooling heat pumps in Valley homes.\281\
---------------------------------------------------------------------------

    \278\ March 2023 Building Electrification Supplement, p. 1.
    \279\ Id.
    \280\ Id. at 1-2. The EPA proposed to approve the District's 
``Burn Cleaner Fireplace and Woodstove Change-out Incentive 
Measure'' into the California SIP on April 14, 2023 (88 FR 22978).
    \281\ March 2023 Building Electrification Supplement, pp. 1-2.
---------------------------------------------------------------------------

    Next, CARB and the District discuss CARB's commitment and ongoing 
work to develop a statewide zero-emission space and water heater 
regulation. CARB included in its 2022 State SIP Strategy for the State 
Implementation Plan (``2022 State SIP Strategy''), among other 
measures, a commitment to develop a zero-emission standard for space 
and water heaters.\282\ CARB submitted the 2022 State SIP Strategy to 
the EPA for approval into the California SIP on February 23, 2023.\283\ 
CARB reiterated its commitment for a zero-emission standard in the 
Final 2022 Scoping Plan for Achieving Carbon Neutrality (``2022 Scoping 
Plan'').\284\ The 2022 State SIP Strategy and 2022 Scoping Plan 
anticipate implementation of a zero-emission standard for building 
heating appliances starting in 2030, pending rule development and CARB 
Board approval in 2025.\285\
---------------------------------------------------------------------------

    \282\ CARB, 2022 State Strategy for the State Implementation 
Plan, pp. 101-103. Available at https://ww2.arb.ca.gov/sites/default/files/2022-08/2022_State_SIP_Strategy.pdf.
    \283\ Letter dated February 22, 2023, from Steven S. Cliff, 
Executive Director, CARB, to Martha Guzman, Regional Administrator, 
EPA Region IX, with enclosures. The EPA has not yet taken action on 
the 2022 State SIP Strategy.
    \284\ CARB, 2022 Scoping Plan, pp. 211-215 and Appendix F.
    \285\ 2022 State SIP Strategy, Table 3.
---------------------------------------------------------------------------

    Third, the State discusses the technical and economic feasibility 
challenges of implementing a zero-emission standard for space and water 
heaters in the San Joaquin Valley. The State summarizes its position in 
the March 2023 Building Electrification Supplement and refers to 
technical and economic feasibility considerations outlined in Appendix 
F of the 2022 Scoping Plan, which CARB included as an attachment to the 
March 2023 Building Electrification Supplement.
    With regard to technical feasibility, CARB acknowledges that 
electric alternatives to gas-fueled appliances are currently available 
for deployment in some applications but cites various challenges 
related to manufacturing capacity, retrofit complications (e.g., 
physical space constraints), consumer awareness/perception, and 
decreased performance of some units in colder climates.\286\ The State 
asserts that consumer preference for appliance types that they are 
already familiar with is a major barrier to building electrification 
and discusses the need for increased consumer awareness and adoption, 
which would allow manufacturers to take advantage of economies of scale 
and increase production capacity.\287\
---------------------------------------------------------------------------

    \286\ 2022 Scoping Plan, pp. 5-10.
    \287\ Id. at Appendix F, p. 22.
---------------------------------------------------------------------------

    With regard to economic feasibility, CARB provides some qualitative 
comparisons between capital and energy costs for electric and natural 
gas-powered appliances, which vary depending on equipment and 
installation needs, climate zones, and energy rate structures.\288\ 
Costs associated with retrofitting an existing building are expected to 
be higher than those for new construction due to the potential for 
additional installation costs, which may include electrical panel and 
circuit upgrades, rewiring, ductwork modifications, and space 
reconfigurations.\289\ Energy costs are expected to vary depending on 
the characteristics of the appliances and buildings, climate variation, 
consumer use patterns, and utility rate structures.\290\ CARB notes 
that higher energy bills after electrification have the potential to 
especially burden low-income residents of the State and discusses the 
importance of coordinating statewide actions to ensure energy rates are 
structured to support electrification.\291\
---------------------------------------------------------------------------

    \288\ Id. at 11-13.
    \289\ Id. at 16-18.
    \290\ Id. at 12.
    \291\ Id. at 13-14.
---------------------------------------------------------------------------

    Additionally, the State posits that low-income customers may be 
less likely to adopt electric appliances early on due to capital costs 
and could end up paying a larger share of systemwide fossil gas system 
costs as other households move away from natural gas use.\292\ With 
regard to the San Joaquin Valley specifically, the District notes that 
the per capita income of District residents is only 40.5 percent of the 
average per capita income of areas in California that have adopted 
building electrification ordinances to date, creating additional 
challenges for implementation in the Valley.\293\ Furthermore, the 
State notes that care must be taken to ensure that vulnerable 
communities are not adversely affected. For example, some rural and 
tribal areas in California rely on propane or wood burning for heating 
because they are not connected to the State's electric grid or natural 
gas infrastructure.\294\ CARB emphasizes the need for robust community 
engagement to ensure equitable consideration of low-income and 
environmental justice communities in the Valley and identifies a need 
for increased incentive funding to support a successful transition to 
building decarbonization.\295\
---------------------------------------------------------------------------

    \292\ Id. at 15.
    \293\ March 2023 Building Electrification Supplement, pp. 2-3. 
The average per capita income of San Joaquin Valley residents is 
$24,708 while the average per capita income in cities with building 
electrification ordinances is $60,969.
    \294\ Id.
    \295\ Id. at Section 4.
---------------------------------------------------------------------------

    Lastly, the State discusses the anticipated implementation 
timelines for zero-NOX building electrification standards in 
the context of the San Joaquin Valley Plan for the 1997 annual 
PM2.5 NAAQS. CARB asserts that the public process to develop 
a rulemaking would take at least two years and that more time would be 
needed for implementation.\296\ As discussed earlier, CARB's adoption 
and implementation timeline for a statewide zero-NOX measure 
involves taking a measure to the CARB Board in 2025 and beginning 
implementation in 2030. This timeline was established to allow adequate 
time for CARB to collaborate with the U.S. Department of Energy; 
California Energy Commission; and California Building Standards 
Commission, Department of Housing and Community Development; and to 
provide time for robust public engagement with community-based 
organizations and other key stakeholders. The State asserts that 
emission reductions from building decarbonization are not feasible in 
the timeframe of the SJV PM2.5 Plan, given the 2023 
attainment date for the 1997 annual PM2.5 NAAQS. The 
District has committed in the 2022 Plan for the 2015 8-Hour Ozone 
Standard to evaluate current and upcoming work by CARB and other 
agencies and to evaluate the feasibility of implementing zero-emission 
NOX requirements for building heating sources in the Valley 
as part of their ongoing work to attain the 2015 ozone NAAQS.\297\
---------------------------------------------------------------------------

    \296\ March 2023 Building Electrification Supplement, p. 4.
    \297\ 2022 Plan for the 2015 8-Hour Ozone Standard, Section 
3.3.4.2.1. Available at https://ww2.valleyair.org/rules-and-planning/air-quality-plans/ozone-plans/2022-ozone-plan-for-the-san-joaquin-valley/.
---------------------------------------------------------------------------

Mobile Sources
    For mobile sources, CARB identifies the sources of direct 
PM2.5 and NOX in the San Joaquin Valley that are 
subject to the State's emissions control measures and provides its 
evaluation of these regulations for compliance with BACM requirements 
in Appendix D of the 15 [micro]g/m\3\ SIP Revision. Appendix D 
describes CARB's process for

[[Page 45305]]

determining BACM, including identification of the sources of direct 
PM2.5 and NOX in the San Joaquin Valley, 
identification of potential control measures for such sources, 
assessment of the stringency and feasibility of the potential control 
measures, and adoption and implementation of feasible control 
measures.\298\
---------------------------------------------------------------------------

    \298\ 15 [micro]g/m\3\ SIP Revision, Appendix D, Chapter II.
---------------------------------------------------------------------------

    Mobile source categories for which CARB has primary responsibility 
for reducing emissions in California include most new and existing on- 
and non-road engines and vehicles and motor vehicle fuels. The SJV 
PM2.5 Plan's BACM demonstration provides a general 
description of CARB's key mobile source programs and regulations and a 
comprehensive table listing on-road and non-road mobile source 
regulatory actions taken by CARB since 1985.\299\
---------------------------------------------------------------------------

    \299\ Id. at Table 17.
---------------------------------------------------------------------------

    Appendix D of the 15 [micro]g/m\3\ SIP Revision also describes the 
current efforts of the eight local jurisdiction metropolitan planning 
organizations (MPOs) to implement cost-effective transportation control 
measures (TCMs) in the San Joaquin Valley.\300\ TCMs are projects that 
reduce air pollutants from transportation sources by reducing vehicle 
use, traffic congestion, or vehicle miles traveled. TCMs are currently 
being implemented in the San Joaquin Valley as part of the Congestion 
Mitigation and Air Quality cost effectiveness policy adopted by the 
eight local jurisdiction MPOs and in the development of each Regional 
Transportation Plan (RTP). The Congestion Mitigation and Air Quality 
policy, which is included in a number of the District's prior 
attainment plan submissions for the ozone and PM2.5 NAAQS, 
provides a standardized process for distributing 20 percent of the 
Congestion Mitigation and Air Quality funds to projects that meet a 
minimum cost effectiveness threshold beginning in fiscal year 2011. The 
MPOs revisited the minimum cost effectiveness standard during the 
development of their 2018 RTPs and 2019 Federal Transportation 
Improvement Program and concluded that they were implementing all 
reasonable transportation control measures.\301\ Appendix D of the 
District's ``2016 Ozone Plan for 2008 8-Hour Ozone Standard,'' adopted 
June 16, 2016, contains a listing of adopted TCMs for the San Joaquin 
Valley.\302\
---------------------------------------------------------------------------

    \300\ Id. at D-127 and D-128.
    \301\ Id. at D-127.
    \302\ Id. and SJVUAPCD, ``2016 Ozone Plan for 2008 8-Hour Ozone 
Standard'' (adopted June 16, 2016), Appendix D, Attachment D, tables 
D-10 to D-17.
---------------------------------------------------------------------------

ii. The EPA's Review of the State's Submission
    We have reviewed the State's and District's analysis and 
determination in the SJV PM2.5 Plan that their baseline 
mobile, stationary, and area source control measures meet the 
requirements for BACM for sources of direct PM2.5 and 
applicable PM2.5 plan precursors (i.e., NOX) for 
purposes of the 1997 annual PM2.5 NAAQS. In our review, we 
considered our evaluation of the State's and District's rules and 
supporting information included in the SJV PM2.5 Plan in 
connection with our approval of the demonstrations for BACM (including 
BACT) and MSM for the 2006 24-hour PM2.5 NAAQS,\303\ our 
approval of the demonstration for BACM for the 1997 24-hour 
PM2.5 NAAQS,\304\ and our proposed disapproval of the 
demonstration for BACM for the 2012 annual PM2.5 NAAQS.\305\ 
We are proposing to find that the evaluation processes followed by CARB 
and the District in the SJV PM2.5 Plan to identify potential 
BACM are generally consistent with the requirements of the 
PM2.5 SIP Requirements Rule, the State's and District's 
evaluation of potential measures is appropriate, and the State and 
District have provided reasoned justifications for their rejection of 
potential measures based on technological or economic infeasibility. We 
also agree with the District's conclusion that all reasonable TCMs are 
being implemented in the San Joaquin Valley and that additional TCMs 
are being considered by the metropolitan transportation agencies as 
part of the Congestion Mitigation and Air Quality cost effectiveness 
policy, with strategies adopted to meet their SB375 greenhouse gas 
reduction targets. Therefore, we propose to find that these TCMs 
implement BACM for transportation sources.
---------------------------------------------------------------------------

    \303\ 85 FR 44192.
    \304\ 87 FR 4503 (January 28, 2022).
    \305\ 86 FR 74310.
---------------------------------------------------------------------------

    With regard to building heating appliances, based on the EPA's 
review of the additional information provided in the March 2023 
Building Electrification Supplement, and for the reasons discussed 
below, we are proposing to approve the State's BACM demonstration for 
NOX and direct PM2.5 emissions from building 
heating appliances for purposes of meeting the CAA requirements for the 
1997 annual PM2.5 NAAQS.
    Consistent with the EPA's prior approvals of the State's BACM 
demonstration for building heating emission sources with respect to the 
2006 24-hour and 1997 24-hour PM2.5 NAAQS, we are proposing 
to find that the State provided a thorough review of measures for 
building heating sources that were being implemented in other 
nonattainment areas at the time the 2018 PM2.5 Plan was 
developed, in accordance with 40 CFR 51.1010(a)(2)(i). The State has 
since updated the analysis to reflect the current facts and 
circumstances for controlling emissions from such sources in 2023 by 
providing a feasibility analysis and an updated evaluation of current 
measures and ongoing efforts by the State and local air districts to 
develop more stringent requirements in the future.
    In accordance with 40 CFR 51.1010(a)(3)(iii), the State has 
provided a detailed justification, based on technical and economic 
feasibility constraints, for why a zero-emission standard for building 
heating appliances is not feasible in the timeframe of the SJV 
PM2.5 Plan for the 1997 annual PM2.5 NAAQS (i.e., 
before the projected attainment date). The State summarized various 
challenges that must be overcome, ranging from increased manufacturing 
to coordination with other State agencies to ensure energy rates are 
structured to support electrification. The State emphasized the need 
for careful consideration of potential adverse effects on low-income 
and environmental justice communities and a robust public process. The 
EPA acknowledges the work that is already underway by CARB to develop a 
statewide zero-emission NOX measure for this source category 
and the recent commitment by the District in its plan for the 2015 
ozone NAAQS to continue to study the feasibility of such standard for 
the San Joaquin Valley specifically.
    With regard to efforts currently underway by the Bay Area AQMD, we 
note that on March 15, 2023, Bay Area AQMD adopted amendments to Rule 
9-4 (``Nitrogen Oxides from Fan Type Residential Central Furnaces'') 
and Rule 9-6 (``Nitrogen Oxides Emissions from Natural Gas-Fired 
Boilers and Water Heaters'').\306\ These rules govern point

[[Page 45306]]

of sale emission standards for small, typically residential and 
commercial, water and space heating systems. The amendments to Rule 9-4 
lower the current NOX emission limit for applicable furnaces 
from 40 ng/J by to 14 ng/J (which matches the limit in SJVUAPCD Rule 
4905) with a compliance date of January 1, 2024; followed by a zero-
NOX emission requirement with a compliance date of January 
1, 2029.\307\ The amendments to Rule 9-6 introduce a zero-
NOX emission standard for residential and commercial water 
heaters and boilers to be implemented by January 1, 2027 and January 1, 
2031 depending on equipment heat rate (i.e., the size of the boiler or 
water heater).\308\
---------------------------------------------------------------------------

    \306\ BAAQMD Board Resolution No. 2023-03, A Resolution of the 
Board of Directors of the Bay Area Air Quality Management District 
Amending Regulation 9, Rule 4 (Nitrogen Oxides from Fan-Type 
Residential Furnaces) and Amending Regulation 9, Rule 6 (Nitrogen 
Oxides Emissions from Natural Gas-Fired Boilers and Water Heaters); 
and Certifying a California Environmental Quality Act Environmental 
Impact Report, March 15, 2023.
    \307\ Final Staff Report, Proposed Amendments to Building 
Appliance Rules--Regulation 9, Rule 4: Nitrogen Oxides from Fan Type 
Residential Central Furnaces and Rule 6: Nitrogen Oxides Emissions 
from Natural Gas-Fired Boilers and Water Heaters, p. 8.
    \308\ Id. at 9.
---------------------------------------------------------------------------

    The fifth step in identifying and selecting controls needed to meet 
BACM/BACT requirements in the PM2.5 SIP Requirements Rule 
involves determining the earliest date by which a control measure or 
technology can be implemented in whole or in part. Accordingly, while 
Bay Area AQMD recently adopted zero-emission requirements for building 
heating sources, its timeframes for implementing those standards (i.e., 
2027-2031) do not conflict with the State's conclusion that a zero-
emission standard is not feasible in the timeframe of the SJV 
PM2.5 Plan for the 1997 annual PM2.5 NAAQS (i.e., 
by the December 31, 2023 attainment date).\309\ Based on measures 
currently being implemented by the Bay Area AQMD, South Coast AQMD, and 
other California air districts as discussed in the SJV PM2.5 
Plan and herein, we agree with the State's conclusion that the 
District's current rules include the most stringent requirements that 
are currently being implemented in the nation for this source category.
---------------------------------------------------------------------------

    \309\ Furthermore, in light of CARB's work towards state-wide 
zero-emission requirements for building heating sources, and a 
recent 9th Circuit opinion on a City of Berkeley ordinance (see 
California Restaurant Association v. City of Berkeley, No. 21-16278 
(9th Cir. 2023)), we note that there is uncertainty as to the exact 
timeline on which such requirements may be implemented.
---------------------------------------------------------------------------

    We note that the District is currently working to develop a new 
Serious area attainment plan for purposes of the 2012 annual 
PM2.5 NAAQS in the San Joaquin Valley. Such plan must 
demonstrate attainment of those NAAQS as expeditiously as practicable 
but no later than December 31, 2025, or by the most expeditious 
alternative date practicable and no later than December 31, 2030, in 
accordance with the requirements of CAA sections 189(b) and 188(e). 
Under CAA section 189(b)(1)(B), the Serious area plan for the 2012 
annual PM2.5 NAAQS must include, among other things, 
provisions to assure that the plan provides for implementation of BACM/
BACT and additional feasible measures for the control of direct 
PM2.5 and PM2.5 precursors. Given the longer time 
horizon of the 2012 annual PM2.5 NAAQS, affording additional 
time for potential control measures to achieve emission reductions that 
may assist in attainment of those NAAQS, we note that nothing in this 
proposal should be interpreted as speaking to whether new measures for 
building heating appliances could be implemented in whole or in part 
within the timeframe of the attainment plan for those NAAQS.
    For the foregoing reasons, we propose to find that the SJV 
PM2.5 Plan provides for the implementation of BACM/BACT for 
sources of direct PM2.5 and NOX as expeditiously 
as practicable in accordance with the requirements of CAA section 
189(b)(1)(B), and in satisfaction of both the Serious area and section 
189(d) plan requirements.
c. Section 189(d) Five Percent Requirement
    The SJV PM2.5 Plan's demonstration of annual five 
percent reductions in NOX emissions is in Chapter 5 
(``Demonstration of Federal Requirements for 1997 PM2.5 
Standard''), Section 5.2 (``5% Plan Demonstration'') of the 15 
[micro]g/m\3\ SIP Revision. As shown in Table 6, the demonstration uses 
the 2013 base year inventory as the starting point from which the five 
percent per year emissions reductions are calculated and uses 2017 as 
the year from which the reductions start. The target required reduction 
in 2017 is five percent of the base year (2013) inventory, which is a 
reduction of approximately 15.9 tpd of NOX, and the targets 
for subsequent years are additional reductions of five percent per year 
until the 2023 attainment year. The projected emissions inventories 
reflect NOX emissions reductions achieved by baseline (i.e., 
already adopted) control measures only and the demonstration shows that 
these NOX emissions reductions are greater than the required 
five percent per year.

      Table 6--2017-2023 Annual Five Percent Emissions Reductions Demonstration for the San Joaquin Valley
----------------------------------------------------------------------------------------------------------------
                                         % Reduction                        CEPAM
                                       from 2013 base  5% Target (tpd     Inventory
                 Year                       year            NOX)         v1.05 (tpd            Meets 5%?
                                          (percent)                         NOX)
----------------------------------------------------------------------------------------------------------------
2013 (base year).....................  ..............  ..............           317.3  .........................
2017.................................               5           301.3           233.4  Yes
2018.................................              10           285.5           221.5  Yes
2019.................................              15           269.6           214.5  Yes
2020.................................              20           253.8           203.3  Yes
2021.................................              25           238.0           191.0  Yes
2022.................................              30           222.1           179.8  Yes
2023.................................              35           206.3           153.6  Yes
----------------------------------------------------------------------------------------------------------------
Source: 15 [micro]g/m\3\ SIP Revision, Table 5-2.

    The EPA proposes to find that the State's use of 2017 as the 
starting point from which the five percent per year emissions 
reductions should begin is reasonable and consistent with the CAA. As 
discussed in Section IV.C.1 of this document, the EPA interprets the 
language under CAA section 189(d) to require a state to submit a new 
attainment plan to achieve annual reductions ``from the date of such 
submission until attainment.'' The 15

[[Page 45307]]

[micro]g/m\3\ SIP Revision was submitted by the State on November 8, 
2021, and the 2018 PM2.5 Plan on which it was based was 
submitted by the State on May 10, 2019. However, the Serious area 
attainment deadline for the San Joaquin Valley nonattainment area for 
the 1997 PM2.5 NAAQS was December 31, 2015.\310\ 
Accordingly, a plan submittal to meet the requirements under section 
189(d) was due by December 31, 2016, and reductions were required to 
occur as of that date. The decline in emissions starting in 2017 shows 
that reductions did, in fact, occur within the required timeframe. 
Furthermore, the State's demonstration shows that NOX 
emissions reductions from 2017 to 2023 are greater than the required 
minimum five percent per year. Thus, the EPA proposes to find that the 
SJV PM2.5 Plan meets the CAA 189(d) requirement to provide 
for an annual reduction in PM2.5 or PM2.5 
precursor emissions of not less than five percent per year of the 
amount of such emissions reported in the most recent inventory prepared 
for the area.
---------------------------------------------------------------------------

    \310\ 80 FR 18528.
---------------------------------------------------------------------------

D. Attainment Demonstration and Modeling

1. Statutory and Regulatory Requirements
    Section 189(b)(1)(A) of the CAA requires that each Serious area 
plan include a demonstration (including air quality modeling) that the 
plan provides for attainment of the PM2.5 NAAQS by the 
applicable attainment date. As discussed at the beginning of Section IV 
of this proposal, given that the outermost statutory Serious area 
attainment date for the San Joaquin Valley area (i.e., December 31, 
2015) has passed and that the EPA has already found that the San 
Joaquin Valley area failed to attain by that date, the EPA must 
evaluate the State's plan for attainment by a later attainment date. 
Given that the finding of failure to attain triggered the State's 
obligation to submit a new plan meeting the requirements of section 
189(d), the EPA is evaluating the SJV PM2.5 Plan in light of 
the outermost attainment date required in section 189(d). That section, 
in conjunction with section 172(a)(2), requires that the attainment 
date be as expeditious as practicable, but not later than five years 
following the EPA's finding that the area failed to attain the NAAQS by 
the applicable Serious area attainment date, except that the EPA may 
extend the attainment date to a date no later than 10 years from the 
date of this determination (i.e., to November 23, 2026), ``considering 
the severity of nonattainment and the availability and feasibility of 
pollution control measures.'' In this case, in the 15 [micro]g/m\3\ SIP 
Revision, the State projected such attainment by December 31, 2023.
    In the PM2.5 SIP Requirements Rule, the EPA explained 
that the same general requirements that apply to Moderate and Serious 
area plans under CAA sections 189(a) and 189(b) should apply to plans 
developed pursuant to CAA section 189(d)--i.e., the plan must include a 
demonstration (including air quality modeling) that the control 
strategy provides for attainment of the PM2.5 NAAQS as 
expeditiously as practicable.\311\ For purposes of determining the 
attainment date that is as expeditious as practicable, the state must 
conduct future year modeling that takes into account emissions growth, 
known controls (including any controls that were previously determined 
to be RACM/RACT or BACM/BACT), the five percent per year emissions 
reductions required by CAA section 189(d), and any other emissions 
controls that are needed for expeditious attainment of the NAAQS.
---------------------------------------------------------------------------

    \311\ 40 CFR 51.1011(b)(1); 81 FR 58010, 58102.
---------------------------------------------------------------------------

    The EPA's PM2.5 modeling guidance \312\ (``Modeling 
Guidance'') recommends that states use a photochemical model, such as 
the Comprehensive Air Quality Model with Extensions (CAMx) or Community 
Multiscale Air Quality Model (CMAQ), to simulate a base case, with 
meteorological and emissions inputs reflecting a base case year, to 
replicate concentrations monitored in that year. The Modeling Guidance 
recommends the following procedures for states to use in attainment 
demonstrations. The model should undergo a performance evaluation to 
ensure that it satisfactorily reproduces the concentrations monitored 
in the base case year. The model may then be used to simulate emissions 
occurring in other years required for an attainment plan, namely the 
base year (which may differ from the base case year) and future 
year.\313\ The Modeling Guidance recommends that the modeled response 
to the emissions changes between the base and future years be used to 
calculate relative response factors (RRFs). The modeled RRFs are 
applied to a monitored base design value (computed from monitored 
concentrations in the base year and neighboring years) to estimate the 
projected design value in the future year, which can be compared 
against the NAAQS. In the recommended procedure, the RRFs are 
calculated for each chemical species component of PM2.5, and 
for each quarter of the year, to reflect their differing responses to 
seasonal meteorological conditions and emissions. These quarterly RRFs 
are applied to base period PM2.5 concentrations that have 
been split into species components, using available chemical species 
measurements. The Modeling Guidance provides additional detail on the 
recommended approach.\314\
---------------------------------------------------------------------------

    \312\ Memorandum dated November 29, 2018, from Richard Wayland, 
Air Quality Assessment Division, Office of Air Quality Planning and 
Standards, EPA, to Regional Air Division Directors, EPA, Subject: 
``Modeling Guidance for Demonstrating Air Quality Goals for Ozone, 
PM2.5, and Regional Haze,'' (``Modeling Guidance'').
    \313\ In this section, we use the terms ``base case,'' ``base 
year'' or ``baseline,'' and ``future year'' as described in Section 
2.3 of the EPA's Modeling Guidance. CARB refers to the base year as 
the ``reference year.''
    \314\ Modeling Guidance, Section 4.4, ``What is the Modeled 
Attainment Tests [sic] for the Annual Average PM2.5 
NAAQS.''
---------------------------------------------------------------------------

2. Summary of the State's Submission
    The 15 [micro]g/m\3\ SIP Revision includes a modeled demonstration 
projecting that the San Joaquin Valley will attain the 1997 annual 
PM2.5 NAAQS by December 31, 2023, based on ongoing emissions 
reductions from baseline control measures, reductions from regulatory 
measures adopted by CARB and the District following development of the 
2018 PM2.5 Plan, and a commitment by CARB to adopt and 
implement an additional regulatory measure to meet an enforceable 
commitment. CARB's updated attainment demonstration for the 15 
[micro]g/m\3\ SIP Revision built upon modeling performed for the 2018 
PM2.5 Plan, applying a scaling procedure described below. 
CARB conducted photochemical modeling with the CMAQ model using inputs 
developed from routinely available meteorological and air quality data, 
as well as more detailed and extensive data from the DISCOVER-AQ field 
study conducted in January and February of 2013.\315\ The Plan's 
primary discussion of the photochemical modeling appears in Appendix K 
(``Modeling Attainment Demonstration'') of the 15 [micro]g/m\3\ SIP 
Revision. The State briefly summarizes the area's air quality problem 
in Chapter 2 (``Air Quality Challenges and Trends'') of the 2018 
PM2.5 Plan and the modeling results in Chapter 5 
(``Demonstration of Federal Requirements for 1997 PM2.5 
Standard''), Section 5.3 (``Attainment Demonstration and Modeling'') of 
the 15 [micro]g/m\3\ SIP Revision. The State provides

[[Page 45308]]

a conceptual model of PM2.5 formation in the San Joaquin 
Valley as part of the modeling protocol in Appendix L (``Modeling 
Protocol'') of the 2018 PM2.5 Plan. Appendix J (``Modeling 
Emission Inventory'') of the 2018 PM2.5 Plan describes 
emissions input preparation procedures. The modeling and its 
documentation are mainly identical to those submitted in the 2018 
PM2.5 Plan, except that Chapter 5 and Appendix K were 
updated to document procedures and results specific to the 2023 
attainment demonstration, including the scaling of some model results. 
The following briefly summarizes the submitted modeling; additional 
details appear in the EPA's ``Technical Support Document, EPA 
Evaluation of Air Quality Modeling, San Joaquin Valley PM2.5 
Plan for the 2006 PM2.5 NAAQS,'' February 2020 (``EPA's 
February 2020 Modeling TSD'') accompanying the EPA's action on the 2018 
PM2.5 Plan for the 2006 PM2.5 NAAQS.
---------------------------------------------------------------------------

    \315\ NASA, ``Deriving Information on Surface conditions from 
COlumn and VERtically Resolved Observations Relevant to Air 
Quality,'' available at https://www.nasa.gov/mission_pages/discover-aq/index.html.
---------------------------------------------------------------------------

    CARB developed a photochemical air quality model application for 
simulating PM2.5 in the San Joaquin Valley. CARB started 
with a conceptual model of PM2.5 formation in the area and a 
modeling protocol describing the following modeling procedures. The 
procedures and their outcomes are also documented in Appendix K. CARB 
selected the episode (i.e., base year) to model, the modeling domain, 
and the modeling platform (CMAQ version 5.0.2); developed initial and 
boundary conditions, and base and future year emissions inventories for 
input into the model; and carried out performance evaluations for both 
the meteorological and photochemical modeling. Finally, CARB used the 
modeled PM2.5 concentration outputs in the numerical NAAQS 
attainment test and in an unmonitored area analysis. These procedures 
are generally consistent with the EPA's recommendations in the Modeling 
Guidance.
    For the 1997 annual PM2.5 NAAQS attainment demonstration 
in the 15 [micro]g/m\3\ SIP Revision, the State relied on existing 
model simulations available from previous work for the 2018 
PM2.5 Plan but applied them differently to reflect more 
recent conditions and a revised 2023 attainment date. To estimate the 
2023 design value, the State used existing simulations to calculate 
RRFs, scaled the RRFs to reflect 2018-2023 emissions changes, and then 
applied the RRFs to a 2018 base design value.
    The State relied on three CMAQ simulations: (1) a 2013 base case 
simulation to demonstrate that the model can reasonably reproduce 
monitored PM2.5 concentrations; (2) a 2020 baseline year or 
``reference'' simulation; and (3) a 2024 future year simulation. The 
2020 and 2024 simulations used projected emissions growth and 
reductions due to controls reflecting those respective years. The State 
carried out these simulations for the 2018 PM2.5 Plan for 
2020 and 2024 attainment demonstrations for various PM2.5 
NAAQS.
    While the State continued to rely on these same model simulations 
for the 15 [micro]g/m\3\ SIP Revision, it applied them differently than 
in the 2018 PM2.5 Plan. For the 15 [micro]g/m\3\ SIP 
Revision, the State calculated a five-year weighted average of 
monitored concentrations, centered on 2018, as the base design value, 
and applied RRFs to the 2018 weighted average to predict the 2023 
design value, as in the procedure recommended in the Modeling Guidance. 
The standard RRF would be the ratio of modeled 2023 concentrations to 
modeled 2018 concentrations, so the RRF would represent the modeled 
PM2.5 change resulting from emissions changes between 2018 
and 2023. Since modeling for the years 2018 and 2023 was not available, 
the State first calculated RRFs from the available 2020 and 2024 
simulations, and then scaled them to account for the emissions changes 
that occur between 2018 and 2023, as shown in the equations in Appendix 
K.\316\ This scaling of the RRFs can also be understood in terms of 
model sensitivity to emissions, since the RRF represents the relative 
change in PM2.5 design value that results from a modeled 
emissions change, i.e., a sensitivity. Essentially, the 2020 and 2024 
model results were used to update the estimate of the sensitivity of 
PM2.5 concentration to emissions. That sensitivity was 
applied to the expected 2018-2023 emissions change, yielding an 
estimate of the 2018-2023 ambient PM2.5 change. The net 
result was that the State used emissions to scale the 2020-2024 RRF in 
order to estimate a 2018-2023 RRF, and then applied the 2018-2023 RRF 
to the 2018 base design value to estimate the 2023 design value. For 
conservatism, if a scaled RRF was lower than the original, the State 
used the higher original one so that the projected PM2.5 
concentration would be higher.
---------------------------------------------------------------------------

    \316\ 15 [micro]g/m\3\ SIP Revision, Appendix K, p. 64 and Table 
31.
---------------------------------------------------------------------------

    The State applied the RRFs to a five-year weighted average base 
design value, consistent with Modeling Guidance recommendations, to 
minimize the influence of year-to-year variability. The base design 
value used monitored concentrations from 2016-2020, centered on 2018. 
This updates the attainment demonstration relative to that in the 2018 
PM2.5 Plan, which used a base design value centered on 2012. 
For Bakersfield-Planz, the site with the highest base design value, the 
base design value concentration was 16.3 [micro]g/m\3\. This 
calculation procedure incorporated the 2020 design value despite its 
``adverse meteorological conditions and increased impacts from 
wildfires'' that contributed to the San Joaquin Valley not attaining 
the 1997 annual NAAQS in 2020.\317\ CARB notes that because 2020 was 
unusual due to the COVID-19 pandemic, it also conducted alternative 
base design value calculations, in which it substituted the average of 
2018 and 2019 for 2020, or simply excluded it, yielding Bakersfield 
base design values of 16.2 and 16.4 [micro]g/m\3\, respectively.
---------------------------------------------------------------------------

    \317\ Id. at 60.
---------------------------------------------------------------------------

    Table 7 shows the 2018 base design values and 2023 projected future 
year annual PM2.5 design values at monitoring sites in the 
San Joaquin Valley. The highest 2023 projected design value is 14.7 
[micro]g/m\3\ at the Bakersfield-California monitoring site, which is 
below the 15.0 [micro]g/m\3\ level of the 1997 annual PM2.5 
NAAQS.\318\
---------------------------------------------------------------------------

    \318\ Id. at 61.

Table 7--Projected Future Annual PM2.5 Design Values at Monitoring Sites
                        in the San Joaquin Valley
                             [[micro]g/m\3\]
------------------------------------------------------------------------
                                                               2023
             Monitoring site                 2018 Base       Projected
                                           design value    design value
------------------------------------------------------------------------
Bakersfield--Planz......................            16.3            14.7
Visalia.................................            15.2            14.0
Bakersfield--Golden State...............            15.1            13.6

[[Page 45309]]

 
Hanford.................................            14.8            12.8
Bakersfield--California Ave.............            14.6            13.2
Corcoran................................            14.3            13.3
Fresno--Hamilton & Winery...............            13.9            13.0
Fresno--Garland.........................            13.3            12.4
Clovis..................................            12.2            11.4
Turlock.................................            12.2            11.3
Stockton................................            11.7            11.1
Merced--S Coffee........................            11.5            10.6
Madera..................................            11.3            10.2
Merced--Main Street.....................            11.3            10.8
Modesto.................................            10.6             9.9
Manteca.................................             9.9             9.4
Tranquility.............................             7.5             6.8
------------------------------------------------------------------------
Source: 15 [micro]g/m\3\ SIP Revision, Table 5-6; and Appendix K, Table
  33.

3. The EPA's Review of the State's Submission
    The EPA previously evaluated the modeling relied upon in the 15 
[micro]g/m\3\ SIP Revision in the context of the attainment 
demonstrations in the 2018 PM2.5 Plan for the 1997 24-hour 
PM2.5 NAAQS, the 2006 24-hour PM2.5 NAAQS, and 
the Moderate area plan for the 2012 PM2.5 NAAQS. For more 
details, see the EPA's February 2020 Modeling TSD. Most aspects of the 
2018 PM2.5 Plan modeling and the EPA's evaluation of it are 
the same for the 24-hour and the annual averaging times, and the EPA 
has found them adequate. These include the modeling protocol, choice of 
model, meteorological modeling, modeling emissions inventory, choice of 
model, modeling domain, and procedures for model performance 
evaluation. However, since the evaluation in the February 2020 Modeling 
TSD reached conclusions for 24-hour average PM2.5, here we 
discuss aspects of the modeling relevant for the annual average, 
including for the 1997 annual PM2.5 NAAQS.
    One aspect that differs between the 24-hour and annual averaging 
times is the specific calculation procedure for estimating a future 
design value. In the procedure recommended in the Modeling Guidance for 
both averaging times, the model is used to calculate RRFs, the ratio of 
modeled future concentrations to base year concentrations, and the RRF 
is applied to monitored base year period concentrations; this is done 
for each monitor, PM2.5 species, and calendar quarter. But 
for the 24-hour averaging time, the recommended procedure is to use the 
highest individual concentration days in each quarter, whereas for the 
annual average, the recommended procedure is to use the average of all 
days in each quarter. For the current action on the 15 [micro]g/m\3\ 
SIP Revision, the EPA finds that the State's procedures \319\ for 
estimating 2020 and 2024 design values for annual average 
PM2.5 generally followed the EPA's recommendations and are 
adequate.
---------------------------------------------------------------------------

    \319\ Id. at 19.
---------------------------------------------------------------------------

    As discussed above, to predict 2023 design values, the State relied 
on model results from 2020 and 2024, using emissions differences to 
calculate scaled RRFs to reflect the modeled effect of emissions 
changes between 2018 and 2023, and then applied these to a 2018 base 
design value. This amounted to scaling model results by applying 
modeled PM2.5 sensitivity (concentration change per 
emissions change) to an updated emissions change. The EPA discussed 
this approach with the State prior to development of the 15 [micro]g/
m\3\ SIP Revision. The EPA has approved comparable scaling in other 
plans, such as the San Joaquin Valley ``2008 PM2.5 Plan'' 
for the 1997 PM2.5 NAAQS,\320\ to account for revised 
emissions estimates for trucks and diesel off-road equipment.\321\ The 
EPA proposed to approve similar scaling for the ``2015 Plan for the 
1997 PM2.5 Standard'' \322\ to account for emissions 
inventory changes relative to the 2008 plan.\323\ In comparison with 
scaling approaches used previously, the RRF scaling approach in the 15 
[micro]g/m\3\ SIP Revision has some advantages. The RRFs are calculated 
on a seasonal basis and account for chemical interactions between the 
separate components of PM2.5 since they incorporate modeled 
changes in all the components simultaneously. The approach thus 
accounts for seasonal variation in model responses and for possible 
nonlinear and nonadditive responses to emissions changes. A simpler 
scaling approach might use only the total PM2.5 as opposed 
to individual PM2.5 components, only annual averages instead 
of quarterly averages, or it may assume that sensitivity to individual 
species emissions changes can be directly added. While these are not 
necessarily incorrect, especially for small emissions changes, the 
approach in the 15 [micro]g/m\3\ SIP Revision of scaling RRFs avoids 
potential inaccuracies resulting from the underlying assumptions of 
simpler approaches.
---------------------------------------------------------------------------

    \320\ CARB submitted the ``2008 PM2.5 Plan'' to the 
EPA on June 30, 2008.
    \321\ 76 FR 69896, November 9, 2011.
    \322\ CARB submitted the ``2015 Plan for the 1997 
PM2.5 Standard'' to the EPA on June 25, 2015.
    \323\ 81 FR 6936, February 9, 2016.
---------------------------------------------------------------------------

    The EPA notes that scaling is not the standard approach for an 
attainment demonstration recommended in the EPA's Modeling Guidance. 
Typically, RRFs are calculated directly from a model prediction for a 
base year, which has undergone a performance evaluation against 
observations, and for a future year; the RRFs are then applied to a 
base design value that reflects monitored data representative of the 
base year. In the 15 [micro]g/m\3\ SIP Revision, the State started from 
the standard RRFs, but adjusted them to reflect the emissions changes 
between two future years; 2018 and 2023 are both future with respect to 
the original 2013 model base case year. The State applied the RRFs to 
recent (2018-centered) monitor data, rather than to data reflective of 
the 2013 base

[[Page 45310]]

case year. This scaling approach is self-consistent and takes advantage 
of existing modeling as well as of more recent emissions and monitoring 
data. Given that the 15 [micro]g/m\3\ SIP Revision is an amendment to 
the 2018 PM2.5 Plan to demonstrate attainment within the 
same statutory timeframe required under section 189(d) of the CAA (as 
discussed in Section I.B of this proposal), and that the scaling 
approach is used for estimating future design values for years close to 
those for which modeling is available, the EPA proposes to find the 
scaling approach used in the 15 [micro]g/m\3\ SIP Revision to be 
acceptable.
    As mentioned above, the State calculated alternative base design 
values to exclude the unusual year of 2020. The State did not discuss 
the 2023 design values derived from those calculations. Since the 
alternative base design values are within 0.1 [micro]g/m\3\ of the 16.3 
[micro]g/m\3\ value that was used, and the projected 14.7 [micro]g/m\3\ 
2023 design value is well below the NAAQS level of 15.0 [micro]g/m\3\, 
those alternative design value calculations would not change the 
conclusion of projected attainment in 2023.
    Another modeling aspect that can differ between 24-hour and annual 
average is the focus of the model performance evaluation on the 
respective averaging times. For the 24-hour average, it is especially 
important that modeled concentrations on the highest days are 
comparable to those on the highest monitored days because calculation 
of the design value for the 24-hour PM2.5 NAAQS uses the 
98th percentile concentrations. For the annual average, peak 
concentrations continue to be important, but lower concentration days 
are also important because all days are included in the average. Under- 
and over-predictions on non-peak days may average out and have little 
overall effect on the modeled annual concentration, but systematic 
underprediction on non-peak days could lead to model underprediction of 
the annual average concentration. This problem of model bias is 
mitigated by the use of the model in a relative sense as recommended in 
the Modeling Guidance. In the RRF, model bias ``cancels out'' to a 
degree since it would be present in both its numerator (future year) 
and its denominator (base year). Applying the RRF to monitored base 
year concentration in this way anchors the final model prediction to 
real-world concentrations. Further, the Modeling Guidance recommends 
that RRFs be calculated on a quarterly basis to better account for 
emissions sources and atmospheric chemistry that differ between the 
seasons.
    The 2018 PM2.5 Plan did not include a separate model 
performance evaluation for the 24-hour and annual PM2.5 
averaging times; the State used statistical and graphical analyses 
applicable to both. The EPA evaluated the modeling for the 1997 annual 
PM2.5 NAAQS using that same information, much of which has 
already been discussed in the EPA's February 2020 Modeling TSD. For the 
most part, in the TSD, the EPA did not distinguish between the two 
averaging times either but drew conclusions for the 24-hour averaging 
time rather than the annual averaging time. We did note a relatively 
large negative normalized bias (underprediction) in the ammonium and 
nitrate performance statistics \324\ for the 2nd quarter for monitoring 
sites in Bakersfield, Fresno, and Visalia; and we add here that the 3rd 
quarter has similar negative bias. Underprediction of total 
PM2.5 in the 2nd and 3rd quarters is also evident in time 
series plots for most monitoring sites, though by only a small amount 
for several monitoring sites.\325\ The RRF procedure removes much of 
this bias, such that the underprediction in the model performance 
evaluation does not translate into an underpredicted future design 
value. The EPA's February 2020 Modeling TSD noted that because the 2nd 
and 3rd quarters have projected concentrations that are less than half 
of the concentrations in the 1st and 4th quarters, this may have a 
small influence on annual average concentrations. (It has even less 
influence on the 24-hour average because peak 24-hour concentrations 
typically occur in winter, i.e., in the 1st and 4th quarters). For 
example, the worst quarterly underprediction for nitrate was for the 
3rd quarter and occurred when the quarterly total PM2.5 
concentration was 9.4 [micro]g/m\3\. By contrast, for the 1st quarter, 
there was a small overprediction in nitrate when the quarterly total 
PM2.5 concentration was 21.1 [micro]g/m\3\. That is, nitrate 
predictions are more biased during the quarters with low 
PM2.5 concentrations. This is apparent from the Plan's 
``bugle'' plot for the four monitors with speciated data.\326\ Large 
(negative) biases in nitrate predictions occur for the lowest quarterly 
nitrate concentrations. For the higher concentrations that have the 
largest effect on the annual average, the nitrate fractional bias is 
sometimes positive and sometimes negative. For total PM2.5, 
the fractional bias has a similar seasonal pattern to that of nitrate, 
with underprediction during the 2nd and 3rd quarters when quarterly 
PM2.5 concentration values are in the 5-10 [micro]g/m\3\ 
range, and a small bias when quarterly concentrations are in the 20-30 
[micro]g/m\3\ range. For the overall annual average, performance is 
good relative to that seen in other modeling studies with lower values 
of bias and error for multiple performance statistics for nitrate, as 
well as for the other PM2.5 species and total 
PM2.5.\327\
---------------------------------------------------------------------------

    \324\ 15 [micro]g/m\3\ SIP Revision, Appendix K, tables 20-23.
    \325\ Id. at figures S.41-S.52.
    \326\ Id. at Figure 13.
    \327\ Id. at Figure 14.
---------------------------------------------------------------------------

    The high PM2.5 concentration days are generally captured 
by the model even though some are underpredicted in December at certain 
monitoring sites such as Fresno. Overall, the modeled site maxima are 
comparable to the measurements. Also, the frequency of high and low 
days generally matches observations so the annual, as well as the 
daily, model performance is acceptable.
    The EPA must make several findings in order to approve the modeled 
attainment demonstration in an attainment plan SIP submission. First, 
we must find that the attainment demonstration's technical bases, 
including the emissions inventories and air quality modeling, are 
adequate. As discussed in Section IV.A of this preamble, we have 
previously approved the emissions inventories on which the SJV 
PM2.5 Plan's attainment demonstration and related provisions 
are based. Furthermore, the EPA has evaluated the State's choice of 
model and the extensive discussion in the Modeling Protocol and 
Appendix K about modeling procedures, tests, and performance 
evaluations. We find that the analyses are consistent with the EPA's 
guidance on modeling for PM2.5 attainment planning purposes. 
Based on these reviews, we find that the modeling in the Plan is 
adequate for the purposes of supporting the RFP demonstration and 
demonstration of attainment by December 31, 2023, and are proposing to 
approve the air quality modeling. For further detail, see the EPA's 
February 2020 Modeling TSD.
    Second, we must find that the SIP submittal provides for 
expeditious attainment through the timely implementation of the control 
strategy, including RACM, BACM, and any other emissions controls that 
are needed for expeditious attainment. As discussed in Section IV.C of 
this preamble, we are proposing to approve the control strategy in the 
SJV PM2.5 Plan, including the BACM/BACT demonstration and 
the five percent emissions reduction

[[Page 45311]]

requirement under CAA sections 189(b)(1)(B) and 189(d), respectively.
    Third, the EPA must find that the emissions reductions that are 
relied on for attainment in the SIP submission are creditable. As 
discussed in Section IV.C.2.a of this document, the SJV 
PM2.5 Plan relies principally on rules that have already 
been adopted and implemented by the State, and approved by the EPA, to 
achieve the emissions reductions needed to attain the 1997 annual 
PM2.5 NAAQS in the San Joaquin Valley by December 31, 2023. 
We present our evaluation of the rules in Section IV.C.2.a of this 
document and in Sections III and IV of the EPA's 1997 Annual 
PM2.5 TSD. We find that all but two of these rules are SIP-
creditable and that the total emissions reductions attributed to the 
two measures that are not SIP-creditable have de minimis impacts on the 
attainment demonstration in the Plan. The balance of the reductions 
that the State has modeled to achieve attainment by this date is 
currently represented by an enforceable commitment that accounts for 
1.8 percent of the NOX and 0.9 percent of the direct 
PM2.5 emissions reductions needed for attainment.
    The EPA may accept enforceable commitments in lieu of adopted 
control measures in attainment demonstrations when the circumstances 
warrant it and the commitments meet the three criteria the EPA has 
established for this purpose. The EPA is proposing to find that 
circumstances here warrant the consideration of enforceable commitments 
and that the three criteria are met: (1) The commitment constitutes a 
limited portion of the required emissions reductions; (2) the State has 
demonstrated its capability to meet their commitments; and (3) the 
commitment is for an appropriate timeframe. We therefore propose to 
approve the State's reliance on the enforceable commitments in its 
attainment demonstration.
    Based on these evaluations, we propose to determine that the SJV 
PM2.5 Plan provides for attainment of the 1997 annual 
PM2.5 NAAQS by the most expeditious date practicable, 
consistent with the requirements of CAA section 189(d). We present the 
basis for this proposed determination in Section IV.C.2.a of this 
proposal. Furthermore, because the December 31, 2015 Serious area 
attainment date has passed, and the EPA found that the area failed to 
attain by the Serious area attainment date, we are evaluating the 
State's compliance with the Serious area plan requirements in light of 
the attainment date required under CAA section 189(d).\328\ For the 
reasons described in this section, in addition to our review of the SJV 
PM2.5 Plan's control measure evaluations, the EPA is 
proposing to approve the attainment date of December 31, 2023 in the 
SJV PM2.5 Plan under section 172(a)(2), given the severity 
of nonattainment in the San Joaquin Valley nonattainment area and the 
feasibility of control measures. We are also proposing to determine 
that the Plan meets the Serious area attainment plan requirements under 
CAA section 189(b)(1)(A).
---------------------------------------------------------------------------

    \328\ See CAA section 172(a)(2) and 179(d); 40 CFR 
51.1004(a)(3).
---------------------------------------------------------------------------

E. Reasonable Further Progress and Quantitative Milestones

1. Statutory and Regulatory Requirements
    Section 172(c)(2) of the CAA provides that all nonattainment area 
plans shall require reasonable further progress (RFP) toward 
attainment. In addition, CAA section 189(c) requires that all 
PM2.5 nonattainment area plans include quantitative 
milestones to be achieved every three years until the area is 
redesignated to attainment and that demonstrate RFP. Section 171(l) of 
the Act defines RFP as ``such annual incremental reductions in 
emissions of the relevant air pollutant as are required by [Part D] or 
may reasonably be required by the Administrator for the purpose of 
ensuring attainment of the applicable [NAAQS] by the applicable date.'' 
Neither subpart 1 nor subpart 4 of part D, title I of the Act requires 
that states achieve a set percentage of emissions reductions in any 
given year for purposes of satisfying the RFP requirement. For purposes 
of the PM2.5 NAAQS, the EPA has interpreted the RFP 
requirement to require that the nonattainment area plans show annual 
incremental emissions reductions sufficient to maintain ``generally 
linear progress'' toward attainment by the applicable deadline.\329\
---------------------------------------------------------------------------

    \329\ General Preamble Addendum, 42015.
---------------------------------------------------------------------------

    Attainment plans for PM nonattainment areas should include detailed 
schedules for compliance with emissions control measures in the area 
and provide corresponding annual emissions reductions to be achieved by 
each milestone in the schedule.\330\ In reviewing an attainment plan 
under subpart 4, the EPA considers whether the annual incremental 
emissions reductions to be achieved are reasonable in light of the 
statutory objective of timely attainment. Although early implementation 
of the most cost-effective control measures is often appropriate, 
states should consider both cost-effectiveness and pollution reduction 
effectiveness when developing implementation schedules for control 
measures and may implement measures that are more effective at reducing 
PM2.5 earlier to provide greater public health 
benefits.\331\
---------------------------------------------------------------------------

    \330\ Id. at 42016.
    \331\ Id.
---------------------------------------------------------------------------

    In addition to the EPA's longstanding guidance on the RFP 
requirements for PM, the Agency has established specific regulatory 
requirements for the PM2.5 NAAQS in the PM2.5 SIP 
Requirements Rule for purposes of satisfying the Act's RFP requirements 
and provides related guidance in the preamble to the rule. 
Specifically, under the PM2.5 SIP Requirements Rule, each 
PM2.5 attainment plan must contain an RFP analysis that 
includes, at minimum, the following four components: (1) an 
implementation schedule for control measures; (2) RFP projected 
emissions for direct PM2.5 and all PM2.5 plan 
precursors for each applicable milestone year, based on the anticipated 
control measure implementation schedule; (3) a demonstration that the 
control strategy and implementation schedule will achieve reasonable 
progress toward attainment between the base year and the attainment 
year; and (4) a demonstration that by the end of the calendar year for 
each triennial milestone date for the area, pollutant emissions will be 
at levels that reflect either generally linear progress or stepwise 
progress in reducing emissions on an annual basis between the base year 
and the attainment year.\332\ Additionally, states should estimate the 
RFP projected emissions for each quantitative milestone year by sector 
on a pollutant-by-pollutant basis.\333\
---------------------------------------------------------------------------

    \332\ 40 CFR 51.1012(a).
    \333\ 81 FR 58010, 58056.
---------------------------------------------------------------------------

    Section 189(c) of the Act requires that PM2.5 attainment 
plans include quantitative milestones that demonstrate RFP. The purpose 
of the quantitative milestones is to allow periodic evaluation of the 
area's progress towards attainment of the PM2.5 NAAQS 
consistent with RFP requirements. Because RFP is an annual emission 
reduction requirement and the quantitative milestones are to be 
achieved every three years, when a state demonstrates compliance with 
the quantitative milestone requirement, it should also demonstrate that 
RFP has been achieved during each of the relevant three years. 
Quantitative milestones should provide an objective means to evaluate 
progress toward

[[Page 45312]]

attainment meaningfully, e.g., through imposition of emissions controls 
in the attainment plan and the requirement to quantify those required 
emissions reductions. The CAA also requires a state to submit, within 
90 days after each three-year quantitative milestone date, a milestone 
report that includes technical support sufficient to document 
completion statistics for appropriate milestones, e.g., of the 
calculations and any assumptions made concerning the emission 
reductions to date.\334\
---------------------------------------------------------------------------

    \334\ CAA section 189(c)(2) and 40 CFR 51.1013(b). See also, 
PM2.5 SIP Requirements Rule, 58065 and General Preamble 
Addendum, 42016-42017.
---------------------------------------------------------------------------

    The CAA does not specify the starting point for counting the three-
year periods for quantitative milestones under CAA section 189(c). In 
the General Preamble and General Preamble Addendum, the EPA interpreted 
the CAA to require that the starting point for the first three-year 
period be the due date for the Moderate area plan submission.\335\ In 
keeping with this historical approach, the EPA established December 31, 
2014, the deadline that the EPA established for a state's submission of 
any additional attainment-related SIP elements necessary to satisfy the 
subpart 4 Moderate area requirements for the 1997 PM2.5 
NAAQS, as the starting point for the first three-year period under CAA 
section 189(c) for the 1997 PM2.5 NAAQS in the San Joaquin 
Valley.\336\
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    \335\ General Preamble, 13539, and General Preamble Addendum, 
42016.
    \336\ 79 FR 31566 (final rule establishing subpart 4 Moderate 
area classifications and deadline for related SIP submissions). 
Although this final rule did not affect any action that the EPA had 
previously taken under CAA section 110(k) on a SIP for a 
PM2.5 nonattainment area, the EPA noted that states may 
need to submit additional SIP elements to fully comply with the 
applicable requirements of subpart 4, even for areas with previously 
approved PM2.5 attainment plans, and that the deadline 
for any such additional plan submissions was December 31, 2014. Id. 
at 31569.
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    Under the PM2.5 SIP Requirements Rule, each attainment 
plan submission for an area designated nonattainment for the 1997 
PM2.5 NAAQS before January 15, 2015, must contain 
quantitative milestones to be achieved no later than three years after 
December 31, 2014, and every three years thereafter until the milestone 
date that falls within three years after the applicable attainment 
date.\337\ If the area fails to attain, this post-attainment date 
milestone provides the EPA with the tools necessary to monitor the 
area's continued progress toward attainment while the state develops a 
new attainment plan.\338\ Quantitative milestones must provide for 
objective evaluation of RFP toward timely attainment of the 
PM2.5 NAAQS in the area and include, at minimum, a metric 
for tracking progress achieved in implementing SIP control measures, 
including BACM and BACT, by each milestone date.\339\
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    \337\ 40 CFR 51.1013(a)(4).
    \338\ 81 FR 58010, 58064.
    \339\ Id. at 58064 and 58092.
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    Because the EPA designated the San Joaquin Valley area as 
nonattainment for the 1997 annual PM2.5 NAAQS effective 
April 5, 2005,\340\ the plan for this area must contain quantitative 
milestones to be achieved no later than three years after December 31, 
2014 (i.e., by December 31, 2017), and every three years thereafter 
until the milestone date that falls within three years after the 
applicable attainment date.\341\ For a Serious area attainment plan 
with a statutory attainment date of December 31, 2015, the relevant 
quantitative milestone year is December 31, 2017. However, as discussed 
in Section III of this proposal, the area did not attain by the 
statutory Serious area attainment date and evaluating reasonable 
further progress toward that date does not make sense. We are therefore 
evaluating the Serious area obligations based on the attainment date 
the State must meet in a plan required under CAA section 189(d).\342\ 
To meet CAA section 189(d), the SJV PM2.5 Plan includes a 
demonstration that the area will attain by December 31, 2023. 
Therefore, in accordance with 40 CFR 51.1013(a)(4), the attainment plan 
for this area must contain quantitative milestones to be achieved no 
later than December 31, 2017, December 31, 2020, December 31, 2023, and 
December 31, 2026.
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    \340\ 70 FR 944.
    \341\ 40 CFR 51.1013(a)(4).
    \342\ See CAA section 179(d); 40 CFR 51.1004(a)(3).
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2. Summary of the State's Submission
    Appendix H (``RFP, Quantitative Milestones, and Contingency'') of 
the 15 [micro]g/m\3\ SIP Revision contains the State's RFP 
demonstration and quantitative milestones for the 1997 annual 
PM2.5 NAAQS, and the Valley State SIP Strategy contains the 
control measure commitments that CARB has identified as mobile source 
quantitative milestones.\343\ Given the State's conclusions that 
ammonia, SOX, and VOC emissions do not contribute 
significantly to PM2.5 levels that exceed the 1997 annual 
PM2.5 NAAQS in the San Joaquin Valley, as discussed in 
Section IV.B of this proposed rule, the RFP demonstration provided by 
the State addresses emissions of direct PM2.5 and 
NOX.\344\ Similarly, the State developed quantitative 
milestones based on the Plan's control strategy measures that achieve 
reductions in emissions of direct PM2.5 and 
NOX.\345\ Appendix H of the 15 [micro]g/m\3\ SIP Revision 
identifies the milestone dates of December 31, 2017, December 31, 2020, 
December 31, 2023, and December 31, 2026, for the 1997 annual 
PM2.5 NAAQS.\346\ The RFP analysis in the Plan shows 
generally linear progress toward attainment of the 1997 annual 
PM2.5 NAAQS.
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    \343\ Valley State SIP Strategy, Table 7 (identifying State 
measures scheduled for action between 2017 and 2023, inter alia) and 
CARB Resolution 18-49, ``San Joaquin Valley Supplement to the 2016 
State Strategy for the State Implementation Plan'' (October 25, 
2018), p. 5 (adopting State commitment to begin public processes and 
propose for Board consideration the list of proposed SIP measures 
outlined in the Valley State SIP Strategy and included in Attachment 
A, according to the schedule set forth therein).
    \344\ 15 [micro]g/m\3\ SIP Revision, Appendix H, p. H-1.
    \345\ Id. at H-18 and H-19 (District milestones) and H-21 and H-
22 (State milestones).
    \346\ Id. at Table H-11.
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    We describe the RFP analysis and quantitative milestones in the SJV 
PM2.5 Plan in greater detail below.
Reasonable Further Progress
    The State addresses the RFP and quantitative milestone requirements 
in Appendix H of the 15 [micro]g/m\3\ SIP Revision. The State estimates 
that emissions of direct PM2.5 and NOX will 
generally decline from the 2013 base year to the projected 2023 
attainment year, and beyond to the 2026 post-attainment quantitative 
milestone year. The Plan's emissions inventory shows that direct 
PM2.5 and NOX are emitted by a large number and 
range of sources in the San Joaquin Valley. Table H-2 in Appendix H 
contains an anticipated implementation schedule for District regulatory 
control measures and Table 4-8 in Chapter 4 of the 15 [micro]g/m\3\ SIP 
Revision contains an anticipated implementation schedule for CARB 
control measures in the San Joaquin Valley. Table H-5 in Appendix H 
contains projected emissions for each quantitative milestone year. 
These emissions levels reflect both baseline emissions projections and 
commitments to achieve additional emission reductions through 
implementation of new control measures by 2023.\347\
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    \347\ Id. at tables H-3 (emissions projections based on baseline 
measures), H-4 (reductions from control measure commitments), and H-
5 (emissions projections accounting for controls). The 15 [micro]g/
m\3\ SIP Revision includes commitments for reductions from new 
control measures by 2023.
---------------------------------------------------------------------------

    The SJV PM2.5 Plan identifies emissions reductions 
needed for attainment of the 1997 annual PM2.5 NAAQS by 
2023,\348\ and identifies San Joaquin Valley's progress toward 
attainment in each milestone year.\349\ The State and District set RFP 
targets for

[[Page 45313]]

each of the quantitative milestone years as shown in Table H-8 of 
Appendix H of the 15 [micro]g/m\3\ SIP Revision.
---------------------------------------------------------------------------

    \348\ Id. at Table H-6.
    \349\ Id. at Table H-7.
---------------------------------------------------------------------------

    According to the Plan, reductions in both direct PM2.5 
and NOX emissions from 2013 base year levels result in 
emissions levels consistent with attainment in the 2023 attainment 
year. Based on these analyses, CARB and the District assert that the 
adopted control strategy and additional commitment for reductions from 
Heavy-Duty I/M by 2023 are adequate to meet the RFP requirement for the 
1997 annual PM2.5 NAAQS.
    The State and District's control strategy for attaining the 1997 
annual PM2.5 NAAQS relies on ongoing emissions reductions 
from baseline measures, emissions reductions from three measures 
adopted following the development of the 2018 PM2.5 Plan and 
prior to adoption of the 15 [micro]g/m\3\ SIP Revision, and an 
aggregate tonnage commitment for the remaining reductions needed for 
attainment. The majority of the NOX and PM2.5 
reductions needed for attainment result from CARB's current mobile 
source control program. The attainment control strategy in the Plan is 
projected to achieve total emission reductions of 156 tpd 
NOX and 4.54 tpd direct PM2.5, of which 98 
percent (153 tpd) and 99 percent (4.5 tpd), respectively, are 
attributed to CARB's baseline mobile source program.\350\ These on-
going controls will thus result in additional reductions in 
NOX and direct PM2.5 emissions between the 2013 
base year and 2023 attainment year.\351\
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    \350\ 15 [micro]g/m\3\ SIP Revision, Chapter 4, Table 4-7.
    \351\ 15 [micro]g/m\3\ SIP Revision, Appendix H, Table H-4.
---------------------------------------------------------------------------

    CARB's mobile source control program provides significant ongoing 
reductions in emissions of direct PM2.5 and NOX 
from on-road and non-road mobile sources, such as light duty vehicles, 
heavy-duty trucks and buses, non-road equipment, and fuels. For on-road 
and non-road mobile sources, which represent the largest sources of 
NOX emissions in the San Joaquin Valley, Appendix H of the 
15 [micro]g/m\3\ SIP Revision identifies five mobile source regulations 
and control programs that limit emissions of direct PM2.5 
and NOX: The On-Road Heavy-Duty Diesel Vehicles (In-Use) 
Regulation (``Truck and Bus Regulation''), the In-Use Off-Road Diesel-
Fueled Fleets Regulation (``Off-Road Regulation''), the California Low-
NOX Engine Standard for new on-road heavy-duty engines used 
in medium and heavy-duty trucks purchased in California, Heavy-Duty I/
M, and the second phase of the Advanced Clean Cars Program (``ACC 
2'').\352\ CARB's mobile source BACM analysis in Appendix D of the 15 
[micro]g/m\3\ SIP Revision provides a more comprehensive overview of 
each of these programs and regulations, among many others.\353\ CARB's 
emission projections for mobile sources are presented in the Plan's 
emissions inventory.\354\
---------------------------------------------------------------------------

    \352\ Id. at H-20 and H-21. Because the ACC 2 measure is not 
scheduled for implementation until 2026 (see 15 [micro]g/m\3\ SIP 
Revision, Table 4-8), which is after the January 1, 2023
    implementation deadline under 40 CFR 51.1011(b)(5) for control 
measures necessary for attainment by December 31, 2023, we are not 
reviewing this program as part of the control strategy in the SJV 
PM2.5 Plan.
    \353\ 15 [micro]g/m\3\ SIP Revision, Appendix D, Chapter IV.
    \354\ 2018 PM2.5 Plan, Appendix B.
---------------------------------------------------------------------------

    The District has also adopted numerous stationary and area source 
rules for direct PM2.5 and NOX emission sources 
that are projected to contribute to RFP and attainment of the 
PM2.5 standards. These include control measures for 
stationary internal combustion engines, residential fireplaces, glass 
manufacturing facilities, agricultural burning sources, and various 
sizes of boilers, steam generators, and process heaters used in 
industrial operations. Appendix H of the 15 [micro]g/m\3\ SIP Revision 
identifies stationary source regulatory control measures implemented by 
the District that achieve ongoing PM2.5 and/or 
NOX reductions through the Plan's RFP milestone years and 
the attainment year.\355\ These measures include rule amendments that 
the District adopted in 2019 through 2022, as summarized in Table 2 of 
the EPA's 1997 Annual PM2.5 TSD. The District's stationary 
and area source BACM analysis in Appendix C of the 2018 
PM2.5 Plan provide a more comprehensive overview of each of 
these programs and regulations, among many others.\356\
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    \355\ 15 [micro]g/m\3\ SIP Revision, Appendix H, Table H-2.
    \356\ 15 [micro]g/m\3\ SIP Revision, Appendix D, Chapter IV, and 
Appendix C.
---------------------------------------------------------------------------

Quantitative Milestones
    Appendix H of the 15 [micro]g/m\3\ SIP Revision identifies December 
31 milestone dates for the 2017 and 2020 RFP milestone years, the 2023 
attainment year, and a post-attainment milestone year of 2026.\357\ 
Appendix H also identifies target emissions levels to meet the RFP 
requirement for direct PM2.5 and NOX emissions 
for each of these milestone years \358\ and control measures that CARB 
and the District plan to implement by each of these years, in 
accordance with the control strategy in the Plan.\359\ The identified 
regulatory measures include State measures for light-duty vehicles and 
non-road vehicles and several District measures for stationary and area 
sources.\360\
---------------------------------------------------------------------------

    \357\ 15 [micro]g/m\3\ SIP Revision, Appendix H, Table H-11.
    \358\ Id. at Table H-5.
    \359\ Id. at H-20 and H-21 (for CARB milestones) and H-17 and H-
18 (for District milestones).
    \360\ Id. at H-18 and H-19 (District milestones), and H-21 and 
H-22 (State milestones).
---------------------------------------------------------------------------

    Specifically, for the 2017 milestone year, Appendix H of the 15 
[micro]g/m\3\ SIP Revision describes the District's quantitative 
milestone as a report on the implementation of several District rules, 
and CARB's quantitative milestones as a report on three measure-
specific milestones: (1) actions taken between 2012 and 2017 to 
implement the Truck and Bus Regulation that required particulate 
filters and cleaner engine standards on existing heavy-duty diesel 
trucks and buses in California; (2) implementation of the ``Advanced 
Clean Cars Program'' (``ACC Program'') between 2014 and 2017; and (3) 
implementation of the ``In-Use Off-Road Diesel-Fueled Fleets 
Regulation'' (``Off-Road Regulation'') between 2014 and 2017.\361\
---------------------------------------------------------------------------

    \361\ Id. at H-21 to H-22.
---------------------------------------------------------------------------

    CARB submitted its 2017 Quantitative Milestone Report for the San 
Joaquin Valley to the EPA on December 20, 2018.\362\ The report 
includes a certification that CARB and the District met the 2017 
quantitative milestones identified in the 2018 PM2.5 Plan 
for the 1997 PM2.5 NAAQS and discusses the State's and 
District's progress on implementing the three CARB measures and six 
District measures identified in Appendix H as quantitative milestones 
for the 2017 milestone year. On February 15, 2021, the EPA determined 
that the 2017 Quantitative Milestone Report was adequate.\363\ In our 
evaluation of the 2017 Quantitative Milestone Report, we found that the 
control measures in the Plan are in effect, consistent with the RFP 
demonstration in the SJV PM2.5 Plan for the 1997 annual 
PM2.5 NAAQS, but we noted that the determination of adequacy 
did not constitute approval of any component of the SJV 
PM2.5 Plan.\364\
---------------------------------------------------------------------------

    \362\ Letter dated December 20, 2018, from Richard W. Corey, 
Executive Officer, CARB, to Michael Stoker, Regional Administrator, 
EPA Region IX, with attachment ``2017 Quantitative Milestone Report 
for the 1997 and 2006 NAAQS.''
    \363\ Letter dated February 15, 2021, from Deborah Jordan, 
Acting Regional Administrator, EPA Region IX, to Richard W. Corey, 
Executive Officer, CARB, with enclosure titled ``EPA Evaluation of 
2017 Quantitative Milestone Report.''
    \364\ Id.

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

[[Page 45314]]

    For the 2020 milestone year, Appendix H of the 15 [mu]g/m\3\ SIP 
Revision describes the District's quantitative milestone as a report on 
``[t]he status of SIP measures adopted between 2017 and 2020 as per the 
schedule included in the adopted Plan.\365\ The schedule for 
development of new or revised SIP measures in the 15 [mu]g/m\3\ SIP 
Revision identifies ``action dates'' between 2017 and 2020 for eight 
District measures listed in tables 4-4 and 4-5 of Chapter 4, including, 
for example, ``Rule 4311, Flares,'' ``Rule 4702, Internal Combustion 
Engines,'' and ``Rule 4901, Wood Burning Fireplaces and Wood Burning 
Heaters.'' \366\ Appendix H describes CARB's quantitative milestone as 
a report on two measure-specific milestones: (1) actions taken between 
2017 and 2020 to implement the Truck and Bus Regulation, and (2) the 
``status of SIP measures adopted between 2017 and 2020, including 
Advanced Clean Cars 2 and the Heavy-Duty Vehicle Inspection and 
Maintenance Program.'' The schedule for development of new or revised 
CARB measures in the 15 [mu]g/m\3\ SIP Revision identifies ``action'' 
dates between 2017 and 2020 for 16 CARB measures listed in Table 4-8 of 
Chapter 4, including, for example, the ``Heavy-Duty Vehicle Inspection 
and Maintenance Program'' and ``Small Off-Road Engines.'' \367\
---------------------------------------------------------------------------

    \365\ 15 [mu]g/m\3\ SIP Revision, Appendix H, p. H-18.
    \366\ 15 [mu]g/m\3\ SIP Revision, Chapter 4, tables 4-4 and 4-5. 
See also email dated November 12, 2019, from Jon Klassen, SJVUAPCD 
to Wienke Tax, EPA Region IX, ``RE: follow up on aggregate 
commitments in SJV PM2.5 plan'' (attaching ``District 
Progress In Implementing Commitments with 2018 PM2.5 
Plan,'' stating the District's intent to take action on the listed 
rules and measures by beginning the public process on each measure 
and then proposing the rule or measure to the SJVUAPCD Governing 
Board).
    \367\ Id. at Table 4-8. See also email dated November 12, 2019, 
from Sylvia Vanderspek, CARB to Anita Lee, EPA Region IX, ``RE: SJV 
PM2.5 information'' (attaching ``Valley State SIP 
Strategy Progress'') and December 2018 Staff Report, pp. 14-15 
(stating CARB's intent to ``bring to the Board or take action on the 
list of proposed State measures for the Valley'' by the action dates 
specified in Table 2).
---------------------------------------------------------------------------

    For the 2023 milestone year, the District's quantitative milestone 
is to report on the status of SIP measures adopted between 2020 and 
2023.\368\ The schedule for development of new or revised SIP measures 
in the 15 [mu]g/m\3\ SIP Revision identifies ``action dates'' in 2021 
and 2022 for ``Rule 4354, Glass Melting Furnaces,'' ``Rule 4352, Solid 
Fuel-Fired Boilers, Steam Generators And Process Heaters,'' and ``Rule 
4550, Conservation Management Practices.'' \369\ Appendix H describes 
CARB's quantitative milestone as a report on actions taken between 2020 
and 2023 to implement (1) the Truck and Bus Regulation, and (2) the 
``California Low-NOX Engine Standard for new on-road heavy-duty engines 
used in medium- and heavy-duty trucks purchased in California.'' \370\
---------------------------------------------------------------------------

    \368\ We note that the District's identified quantitative 
milestone for 2023 on page H-18 of Appendix H contains a 
typographical error, as it includes a District report on ``[t]he 
status of SIP measures adopted between 2017 and 2020 as per the 
schedule included in the adopted Plan.'' SJVUAPCD confirmed via an 
email that the District intended to refer here to the status of SIP 
measures adopted between 2020 and 2023, consistent with the schedule 
in the 15 [mu]g/m\3\ SIP Revision. See email dated January 26, 2022, 
from Jon Klassen, SJVUAPCD, to Ashley Graham, EPA Region IX, 
``Subject: FW: 2023 QM Report commitment in Attainment Plan 
Revision.''
    \369\ 15 [mu]g/m\3\ SIP Revision, Chapter 4, Table 4-4.
    \370\ 15 [mu]g/m\3\ SIP Revision, Appendix H, p. H-22.
---------------------------------------------------------------------------

    Finally, for the 2026 milestone year, Appendix H of the 15 [mu]g/
m\3\ SIP Revision describes the District's quantitative milestone as a 
report on (1) ``[i]mplementation of amendments to [the] Residential 
Wood Burning Strategy, including any regulatory amendments to the 
District Burn Cleaner incentive program''; (2) ``[i]mplementation of 
amendments to [the] Commercial Under-Fired Strategy, including any 
regulatory amendments and implementation of [the] related incentive-
based strategy; and (3) ``[t]he status of SIP measures adopted between 
2023 and 2026 as per the schedule included in the adopted Plan.\371\ 
The schedule for development of new or revised SIP measures in the 15 
[mu]g/m\3\ SIP Revision identifies ``implementation begins'' dates of 
2023 and 2024 for seven District measures listed in Table 4-4 of 
Chapter 4, and ``ongoing'' implementation for three incentive-based 
measures in Table 4-5. Appendix H describes CARB's quantitative 
milestone as a report on (1) the number of pieces of agricultural 
equipment upgraded to Tier 4 through 2026 due to the ``Accelerated 
Turnover of Agricultural Tractors Measure,'' and (2) the number of 
trucks and buses upgraded to a low-NOX engine or cleaner 
through 2026 due to the ``Accelerated Turnover of Trucks and Buses 
Measure.'' \372\
---------------------------------------------------------------------------

    \371\ Id. at H-19.
    \372\ Id. at H-22.
---------------------------------------------------------------------------

3. The EPA's Review of the State's Submission
Reasonable Further Progress
    The EPA has evaluated the RFP demonstration in Appendix H of the 15 
[micro]g/m\3\ SIP Revision and, for the following reasons, proposes to 
find that it satisfies the statutory and regulatory requirements for 
RFP.
    First, the Plan contains an anticipated implementation schedule for 
the attainment control strategy, including all BACM and BACT control 
measures and CARB's aggregate tonnage commitment, as required by 40 CFR 
51.1012(a)(1). The implementation schedule is found in tables 4-4, 4-5, 
and 4-8 of the 15 [micro]g/m\3\ SIP Revision and in Table H-2 of 
Appendix H. The 15 [micro]g/m\3\ SIP Revision documents the State's, 
District's, and MPOs' conclusions that they are implementing all BACM/
BACT and additional feasible measures for direct PM2.5 and 
NOX emissions in the San Joaquin Valley as expeditiously as 
practicable.\373\
---------------------------------------------------------------------------

    \373\ The BACM/BACT control strategy that provides the basis for 
these emissions projections is described in Chapter 4, Appendix C, 
and Appendix D of the 15 [micro]g/m\3\ SIP Revision.
---------------------------------------------------------------------------

    Second, the RFP demonstration presents projected emissions levels 
for direct PM2.5 and NOX to be achieved by each 
applicable milestone year as required by 40 CFR 51.1012(a)(2). These 
projections are based on the continued implementation of existing 
control measures in the area (i.e., baseline measures) and the 
commitment by CARB to achieve additional emissions reductions by 2023, 
and reflect full implementation of the State's, District's, and MPOs' 
attainment control strategy for these pollutants.
    Third, the projected emissions levels based on the implementation 
schedule in the Plan demonstrate that the control strategy will achieve 
direct PM2.5 and NOX emissions reductions at 
rates representing generally linear progress towards attainment between 
the 2013 baseline year and the 2023 attainment year as required by 40 
CFR 51.1012(a)(3). The projected emissions levels for 2017, 2020, 2023, 
and 2026 are approximately at or below the target RFP emission levels 
for each year, and the decreases in emissions levels lead to the 
achievement of the reductions required for attainment in 2023. The 
target emissions levels and associated control requirements provide for 
objective evaluation of the area's progress towards attainment of the 
1997 annual PM2.5 NAAQS.
    For these reasons, we propose to determine that the SJV 
PM2.5 Plan satisfies the requirements for RFP in CAA section 
172(c)(2) and 40 CFR 51.1012 for the 1997 annual PM2.5 NAAQS 
in the San Joaquin Valley.
Quantitative Milestones
    Appendix H of the 15 [micro]g/m\3\ SIP Revision identifies 
milestone dates (i.e.,

[[Page 45315]]

December 31 of 2017, 2020, 2023, and 2026) that are consistent with the 
requirements of 40 CFR 51.1013(a)(4). The Plan also identifies target 
emissions levels for direct PM2.5 and NOX to be 
achieved by these milestone dates through implementation of the control 
strategy. These target emissions levels and associated control 
requirements provide for objective evaluation of the area's progress 
towards attainment of the 1997 annual PM2.5 NAAQS.
    CARB and District's quantitative milestones in Appendix H are to 
implement specific measures identified in the Plan. These milestones 
provide an objective means for tracking CARB and the District's 
progress in implementing their respective control strategies and thus, 
provide for objective evaluation of the San Joaquin Valley's progress 
toward timely attainment. For these reasons, we propose to determine 
that the SJV PM2.5 Plan satisfies the requirements for 
quantitative milestones in CAA section 189(c) and 40 CFR 51.1013 for 
the 1997 annual PM2.5 NAAQS in the San Joaquin Valley for 
purposes of both the Serious area and CAA section 189(d) attainment 
plans.
    We note that on April 1, 2021, CARB submitted the San Joaquin 
Valley ``2020 Quantitative Milestone Report for the 1997 and 2006 
NAAQS'' (``2020 QM Report'') to the EPA.\374\ The EPA is currently 
reviewing the 2020 QM Report and will determine, as part of its 
determination on the submitted report, whether the State and District 
have met their identified quantitative milestones for 2020.
---------------------------------------------------------------------------

    \374\ Letter dated March 30, 2021, from Richard W. Corey, 
Executive Officer, CARB, to Deborah Jordan, Acting Regional 
Administrator, EPA Region 9, with enclosure.
---------------------------------------------------------------------------

F. Motor Vehicle Emission Budgets

1. Statutory and Regulatory Requirements
    Section 176(c) of the CAA requires federal actions in nonattainment 
and maintenance areas to conform to the goals of the state's SIP to 
eliminate or reduce the severity and number of violations of the NAAQS 
and achieve timely attainment of the NAAQS. Conformity to the SIP's 
goals means that such actions will not: (1) cause or contribute to 
violations of a NAAQS; (2) increase the frequency or severity of an 
existing violation; or (3) delay timely attainment of any NAAQS or any 
interim milestone.
    Actions involving Federal Highway Administration (FHWA) or Federal 
Transit Administration (FTA) funding or approval are subject to the 
EPA's transportation conformity rule, codified at 40 CFR part 93, 
subpart A (``Transportation Conformity Rule''). Under this rule, 
metropolitan planning organizations (MPOs) in nonattainment and 
maintenance areas coordinate with state and local air quality and 
transportation agencies, the EPA, FHWA, and FTA to demonstrate that an 
area's regional transportation plans (RTPs) and transportation 
improvement programs conform to the applicable SIP. This demonstration 
is typically done by showing that estimated emissions from existing and 
planned highway and transit systems are less than or equal to the motor 
vehicle emission budgets (``budgets'') contained in all control 
strategy plans applicable to the area. An attainment plan for the 
PM2.5 NAAQS must include budgets for each RFP milestone year 
and the attainment year, as appropriate, for direct PM2.5 
and PM2.5 precursors subject to transportation conformity 
analyses. Budgets are generally established for specific years and 
specific pollutants or precursors and must reflect all motor vehicle 
control measures contained in the attainment and RFP 
demonstrations.\375\
---------------------------------------------------------------------------

    \375\ 40 CFR 93.118(e)(4)(v).
---------------------------------------------------------------------------

    Under the PM2.5 SIP Requirements Rule, Serious area 
PM2.5 attainment plans must include appropriate quantitative 
milestones and projected RFP emissions levels for direct 
PM2.5 and all PM2.5 plan precursors in each 
milestone year.\376\ For an area designated nonattainment for the 1997 
PM2.5 NAAQS before January 15, 2015, the attainment plan 
must contain quantitative milestones to be achieved no later than three 
years after December 31, 2014, and every three years thereafter until 
the milestone date that falls within three years after the applicable 
attainment date.\377\ As the EPA explained in the preamble to the 
PM2.5 SIP Requirements Rule, it is important to include a 
post-attainment year quantitative milestone to ensure that, if the area 
fails to attain by the attainment date, the EPA can continue to monitor 
the area's progress toward attainment while the state develops a new 
attainment plan.\378\ Although the post-attainment year quantitative 
milestone is a required element of a Serious area plan, it is not 
necessary to demonstrate transportation conformity for the post-
attainment year or to use the post-attainment year budgets in 
transportation conformity determinations until such time as the area 
fails to attain the 1997 annual PM2.5 NAAQS.
---------------------------------------------------------------------------

    \376\ 40 CFR 51.1012(a), 51.1013(a)(2).
    \377\ 40 CFR 51.1013(a)(4) and 81 FR 58010, 58058 and 58063-
58064. Because the area has failed to attain the 1997 annual 
PM2.5 NAAQS by the Serious area attainment date, the 
applicable attainment date for the purposes of our evaluation is the 
section 189(d) projected attainment date of December 31, 2023.
    \378\ 81 FR 58010, 58063-58064.
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    PM2.5 plans should identify budgets for direct 
PM2.5, NOX, and all other PM2.5 
precursors for which on-road emissions are determined to significantly 
contribute to PM2.5 levels in the area for each RFP 
milestone year and the attainment year, if the plan demonstrates 
attainment. All direct PM2.5 SIP budgets should include 
direct PM2.5 from tailpipe, brake wear, and tire wear motor 
vehicle emissions. With respect to emissions of VOC, SO2, 
and/or ammonia, the transportation conformity provisions of 40 CFR part 
93, subpart A, apply only if the EPA Regional Administrator or the 
director of the state air agency has made a finding that 
transportation-related emissions of these precursors within the area 
are a significant contributor to the PM2.5 nonattainment 
problem and has so notified the MPO and Department of Transportation 
(DOT), or if the applicable implementation plan (or implementation plan 
submission) includes any of these precursors in the approved (or 
adequate) budget as part of the RFP, attainment, or maintenance 
strategy.\379\ With respect to PM2.5 from re-entrained road 
dust, the transportation conformity provisions of 40 CFR part 93, 
subpart A apply if the EPA Regional Administrator or the director of 
the state air agency has made a finding that re-entrained road dust 
emissions within the area are a significant contributor to the 
PM2.5 nonattainment problem and has so notified the MPO and 
DOT, or if the applicable implementation plan (or implementation plan 
submission) includes re-entrained road dust in the approved (or 
adequate) budget as part of the reasonable further progress, 
attainment, or maintenance strategy.\380\ Similarly, for 
PM2.5 from construction emissions, the transportation 
conformity provisions of 40 CFR part 93, subpart A apply if the area's 
implementation plan identifies construction-related fugitive 
PM2.5 as a significant contributor to the nonattainment 
problem.\381\
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    \379\ 40 CFR 93.102(b)(2)(v); see also Conformity Rule preambles 
at 69 FR 40004, 40031-40034 (July 1, 2004) and 70 FR 24280, 24283-
24285 (May 6, 2005).
    \380\ 40 CFR 93.102(b)(3).
    \381\ 40 CFR 93.122(f); see also Conformity Rule preambles at 69 
FR 40004, 40035-40036 (July 1, 2004).
---------------------------------------------------------------------------

    In addition, transportation conformity requirements apply with 
respect to emissions of NOX in PM2.5 areas unless

[[Page 45316]]

both the EPA Regional Administrator and the director of the state air 
agency have made a finding that transportation-related emissions of 
NOX within the nonattainment area are not a significant 
contributor to the PM2.5 nonattainment problem and have so 
notified the MPO and DOT, or the applicable implementation plan (or 
implementation plan submission) does not establish an approved (or 
adequate) budget for such emissions as part of the RFP, attainment, or 
maintenance strategy.\382\
---------------------------------------------------------------------------

    \382\ 40 CFR 93.102(b)(2)(iv).
---------------------------------------------------------------------------

    It is not always necessary for states to establish motor vehicle 
emissions budgets for all PM2.5 precursors. The 
PM2.5 SIP Requirements Rule allows a state to demonstrate 
that emissions of certain precursors do not contribute significantly to 
PM2.5 levels that exceed the NAAQS in a nonattainment area, 
in which case the state may exclude such precursor(s) from its control 
evaluations for the specific NAAQS at issue. If a state successfully 
demonstrates that the emissions of one or more of the PM2.5 
precursors from all sources do not contribute significantly to 
PM2.5 levels in the subject area, then it is not necessary 
to establish motor vehicle emissions budgets for such precursor(s) 
consistent with the applicability requirements of the transportation 
conformity regulations (40 CFR 93.102(b)(2)(v)).\383\
---------------------------------------------------------------------------

    \383\ 81 FR 58010, 58055, 58058, and 58090.
---------------------------------------------------------------------------

    Additionally, the transportation conformity regulations contain 
criteria for determining whether emissions of one or more 
PM2.5 precursors are insignificant for transportation 
conformity purposes.\384\ For a pollutant or precursor to be considered 
an insignificant contributor based on the transportation conformity 
rule's criteria, the control strategy SIP must demonstrate that it 
would be unreasonable to expect that such an area would experience 
enough motor vehicle emissions growth in that pollutant and/or 
precursor for a NAAQS violation to occur. Insignificance determinations 
are based on factors such as air quality, SIP-approved motor vehicle 
control measures, trends and projections of motor vehicle emissions, 
and the percentage of the total attainment plan emissions inventory for 
the NAAQS at issue that is comprised of motor vehicle emissions. The 
EPA's explanation for providing for insignificance determinations is 
described in the July 1, 2004, revision to the Transportation 
Conformity Rule.\385\
---------------------------------------------------------------------------

    \384\ 40 CFR 93.109(f).
    \385\ 69 FR 40004.
---------------------------------------------------------------------------

    Transportation conformity trading mechanisms are allowed under 40 
CFR 93.124 where a state establishes appropriate mechanisms for such 
trades. The basis for the trading mechanism is the SIP attainment 
modeling that establishes the relative contribution of each 
PM2.5 precursor pollutant. The applicability of emissions 
trading between conformity budgets for conformity purposes is described 
in 40 CFR 93.124(b).
    The EPA's process for determining the adequacy of a budget consists 
of three basic steps: (1) notifying the public of a SIP submittal; (2) 
providing the public the opportunity to comment on the budgets during a 
public comment period; and (3) making a finding of adequacy or 
inadequacy.\386\ The EPA can notify the public by either posting an 
announcement that the EPA has received SIP budgets on the EPA's 
adequacy website,\387\ or through a Federal Register notice of proposed 
rulemaking when the EPA reviews the adequacy of an implementation 
plan's budgets simultaneously with its review and action on the SIP 
itself.\388\
---------------------------------------------------------------------------

    \386\ 40 CFR 93.118(f).
    \387\ 40 CFR 93.118(f)(1).
    \388\ 40 CFR 93.118(f)(2).
---------------------------------------------------------------------------

2. Summary of the State's Submission
    The 15 [micro]g/m\3\ SIP Revision includes budgets for direct 
PM2.5 and NOX emissions, calculated using annual 
average daily emissions, for 2017 (RFP milestone year), 2020 (RFP 
milestone year), 2023 (attainment year), and 2026 (post-attainment 
quantitative milestone year).\389\ The Plan establishes separate direct 
PM2.5 and NOX subarea budgets for each county, 
and partial county (for Kern County), in the San Joaquin Valley.\390\ 
CARB calculated the budgets using EMFAC2014.\391\ At the time that the 
emissions inventories and other underlying technical information in the 
2018 PM2.5 Plan was developed, EMFAC2014 was CARB's latest 
version of the EMFAC model for estimating emissions from on-road 
vehicles operating in California that was approved by the EPA. CARB 
calculated the latest modeled vehicle miles traveled and speed 
distributions from the most recently amended 2017 Federal Statewide 
Transportation Improvement Program (FSTIP) for each MPO as of January 
2018. The budgets reflect annual average emissions consistent with the 
annual averaging period for the 1997 annual PM2.5 NAAQS and 
the SJV PM2.5 Plan's RFP and 5 percent demonstrations.
---------------------------------------------------------------------------

    \389\ 15 [micro]g/m\3\ SIP Revision, Appendix D, Table 18.
    \390\ 40 CFR 93.124(c) and (d).
    \391\ EMFAC is short for EMission FACtor. The EPA announced the 
availability of the EMFAC2014 model for use in state implementation 
plan development and transportation conformity in California on 
December 14, 2015. The EPA's approval of the EMFAC2014 emissions 
model for SIP and conformity purposes was effective on the date of 
publication of the notice in the Federal Register.
---------------------------------------------------------------------------

    The direct PM2.5 budgets include tailpipe, brake wear, 
and tire wear emissions but do not include paved road dust, unpaved 
road dust, and road construction dust emissions.\392\ The State is not 
required to include re-entrained road dust in the budgets under section 
93.103(b)(3) and 93.122(f) unless the EPA or the State has made a 
finding that these emissions are significant. Neither the State nor the 
EPA has made such a finding, but the Plan does include a discussion of 
the significance/insignificance factors for re-entrained road 
dust.\393\ The budgets included in the SJV PM2.5 Plan for 
purposes of the 1997 annual PM2.5 NAAQS are shown in Table 
8.
---------------------------------------------------------------------------

    \392\ 15 [micro]g/m\3\ SIP Revision, Appendix D, pp. D-122 and 
D-123.
    \393\ Id. at D-121 and D-122.

                           Table 8--Motor Vehicle Emission Budgets for the San Joaquin Valley for the 1997 Annual PM2.5 NAAQS
                                                                  [Annual average, tpd]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                       2017 (RFP year)           2020 (RFP year)       2023 (Attainment year)     2026 (Post-Attainment
                                                 ------------------------------------------------------------------------------           year)
                     County                                                                                                    -------------------------
                                                     PM2.5         NOX         PM2.5         NOX         PM2.5         NOX         PM2.5         NOX
--------------------------------------------------------------------------------------------------------------------------------------------------------
Fresno..........................................          0.9         28.5          0.9         25.3          0.8         15.1          0.8         14.0
Kern............................................          0.8         28.0          0.8         23.3          0.7         13.3          0.8         12.5
Kings...........................................          0.2          5.8          0.2          4.8          0.2          2.8          0.2          2.6
Madera..........................................          0.2          5.3          0.2          4.2          0.2          2.5          0.2          2.2
Merced..........................................          0.3         10.7          0.3          8.9          0.3          5.3          0.3          4.8

[[Page 45317]]

 
San Joaquin.....................................          0.7         14.9          0.6         11.9          0.6          7.6          0.6          6.7
Stanislaus......................................          0.4         11.9          0.4          9.6          0.4          6.1          0.4          5.4
Tulare..........................................          0.4         10.8          0.4          8.5          0.4          5.2          0.4          4.5
--------------------------------------------------------------------------------------------------------------------------------------------------------
Source: 15 [micro]g/m\3\ SIP Revision, Appendix D, Table 18. Budgets are rounded up to the nearest tenth of a ton.

    The State did not include budgets for VOC, SO2, or 
ammonia. As discussed in Section IV.B of this proposed rule, the State 
submitted a PM2.5 precursor demonstration documenting its 
conclusion that control of these precursors would not significantly 
contribute to attainment of the 1997 annual PM2.5 NAAQS, and 
the EPA is proposing to approve the precursor demonstration. Therefore, 
if the EPA approves the demonstration, consistent with the 
transportation conformity regulation (40 CFR 93.102(b)(2)(v)), the 
State would not be required to submit budgets for these precursors. The 
State included a discussion of the significance/insignificance factors 
for ammonia, SO2, and VOC to demonstrate a finding of 
insignificance under the transportation conformity rule.\394\
---------------------------------------------------------------------------

    \394\ Id.
---------------------------------------------------------------------------

Conformity Trading Mechanism
    The 15 [micro]g/m\3\ SIP Revision also includes a proposed trading 
mechanism for transportation conformity analyses that would allow the 
MPOs in the area to use future decreases in NOX emissions 
from on-road mobile sources to offset any on-road increases in direct 
PM2.5 emissions. In the SJV PM2.5 Plan, the 
approximate weighting ratios of the precursor emissions for annual 
average PM2.5 formation in equivalent tons per day of 
NOX are 6.5 to 1 (i.e., reducing 6.5 tons of NOX 
is equivalent to reducing one ton of PM2.5). Therefore, if 
an MPO found, while preparing a conformity determination that on-road 
emissions of direct PM2.5 were exceeding the direct 
PM2.5 motor vehicle emissions budget, it could use any 
excess NOX reductions to offset the excess direct 
PM2.5 emissions by applying the trading ratio of 6.5 tons of 
NOX emissions to 1 ton of direct PM2.5 emissions. 
This ratio was derived by performing a sensitivity analysis based on a 
30 percent reduction of NOX or PM2.5 emissions 
and calculating the corresponding effect on design values at sites in 
Bakersfield and Fresno (i.e., an updated analysis relative to the 2008 
PM2.5 Plan for the 1997 PM2.5 NAAQS). For 
comparison, in approving the budgets for the 2008 PM2.5 Plan 
for the 1997 PM2.5 NAAQS, the EPA approved a trading 
mechanism for transportation conformity analyses that allowed for such 
one-way trades (i.e., only excess NOX can be used to offset 
PM2.5, not vice versa) at a 9 to 1 NOX to 
PM2.5 ratio.\395\
---------------------------------------------------------------------------

    \395\ 76 FR 69896, 69923 (November 9, 2011).
---------------------------------------------------------------------------

    To ensure that the trading mechanism does not affect the ability of 
the San Joaquin Valley to meet the NOX budget, the 
NOX emission reductions available to supplement the 
PM2.5 budget would only be those remaining after the 
NOX budget has been met.\396\ The Plan also provides that 
the San Joaquin Valley MPOs shall clearly document the calculations 
used in the trading, along with any additional reductions of 
NOX and PM2.5 emissions in the conformity 
analysis.
---------------------------------------------------------------------------

    \396\ 15 [micro]g/m\3\ SIP Revision, Appendix D, pp. D-126 and 
D-127.
---------------------------------------------------------------------------

3. The EPA's Review of the State's Submission
    Generally, the EPA first conducts a preliminary review of budgets 
submitted with an attainment plan for PM2.5 for adequacy, 
prior to taking action on the plan itself, and did so in this case with 
respect to the PM2.5 budgets in the SJV PM2.5 
Plan. On November 15, 2021, the EPA announced the availability of the 
15 [micro]g/m\3\ SIP Revision with budgets and a 30-day public comment 
period. This announcement was posted on the EPA's Adequacy website at: 
https://www.epa.gov/state-and-local-transportation/state-implementation-plans-sip-submissions-currently-under-epa. The comment 
period for this notification ended on December 15, 2021. We did not 
receive any comments during this comment period.
    The EPA determined that the budgets in the 15 [micro]g/m\3\ SIP 
Revision are adequate for use for transportation conformity purposes. 
In a letter dated February 1, 2022, the EPA notified CARB and other 
agencies involved in the interagency consultation process in the San 
Joaquin Valley that we had reviewed the 2020 RFP and 2023 attainment 
year budgets in the 15 [micro]g/m\3\ SIP Revision and found that they 
are adequate for transportation conformity purposes.\397\ The EPA 
announced the availability of the budgets and notified the public of 
the adequacy finding via a Federal Register notice on February 10, 
2022.\398\ This adequacy finding became effective on February 25, 2022 
and the budgets have been used in transportation conformity 
determinations in the San Joaquin Valley area since that date. In this 
action, we are reviewing the budgets for approval into the California 
SIP.
---------------------------------------------------------------------------

    \397\ Letter dated February 1, 2022, from Matthew Lakin, Acting 
Director, Air and Radiation Division, EPA Region IX, to Richard 
Corey, Executive Officer, CARB.
    \398\ 87 FR 7834 (February 10, 2022).
---------------------------------------------------------------------------

    Based on our proposal to approve the State's demonstration that 
emissions of ammonia, SO2, and VOCs do not contribute 
significantly to PM2.5 levels that exceed the 1997 annual 
PM2.5 NAAQS in the San Joaquin Valley, as discussed in 
Section IV.B of this proposal, and the information about ammonia, 
SO2, and VOC emissions in the Plan, the EPA proposes to find 
that it is not necessary to establish motor vehicle emissions budgets 
for transportation-related emissions of ammonia, SO2, and 
VOC to attain the 1997 annual PM2.5 NAAQS in the San Joaquin 
Valley. Based on the information about re-entrained road dust in the 
Plan,\399\ and in accordance with 40 CFR 93.102(b)(3) and 93.122(f), 
the EPA proposes to find that it is not necessary to include re-
entrained road dust emissions in the budgets for 1997 annual 
PM2.5 NAAQS in the San Joaquin Valley.
---------------------------------------------------------------------------

    \399\ 15 [micro]g/m\3\ SIP Revision, Appendix D, pp. D-121 to D-
123.
---------------------------------------------------------------------------

    For the reasons discussed in Sections IV.D and IV.E of this 
proposed rule, the EPA is proposing to approve the

[[Page 45318]]

attainment, RFP, and 5 percent demonstrations, respectively, in the SJV 
PM2.5 Plan. The 2020 RFP and 2023 attainment year budgets, 
as shown in Table 8 of this proposed rule, are consistent with these 
demonstrations, are clearly identified and precisely quantified, and 
meet all other applicable statutory and regulatory requirements 
including the adequacy criteria in 40 CFR 93.118(e)(4) and (5). For 
these reasons, the EPA proposes to approve the 2020 and 2023 budgets 
listed in Table 8. We provide a more detailed discussion in Section VI 
of the EPA's 1997 Annual PM2.5 TSD. We are not proposing to 
approve the 2017 budgets \400\ or the post-attainment year 2026 budgets 
at this time. The budgets that the EPA is proposing to approve relate 
only to the 1997 annual PM2.5 NAAQS, and our proposed 
approval does not affect the status of the previously-approved budgets 
for the 1997 24-hour PM2.5 NAAQS, the 2006 PM2.5 
NAAQS, or the 2012 PM2.5 NAAQS and related trading 
mechanisms that remain in effect for those PM2.5 NAAQS.
---------------------------------------------------------------------------

    \400\ We are not proposing to approve the 2017 budgets because 
such budgets would not be used in any future transportation 
conformity determination because the Plan includes budgets for 2020.
---------------------------------------------------------------------------

    Although the post-attainment year quantitative milestone is a 
required element of the Serious area plan, it is not necessary to 
demonstrate transportation conformity for 2026 or to use the 2026 
budgets in transportation conformity determinations until such time as 
the area fails to attain the 1997 annual PM2.5 NAAQS. 
Therefore, the EPA is not taking action on the submitted budgets for 
2026 in the SJV PM2.5 Plan at this time. Additionally, the 
EPA has not yet started the adequacy process for the 2026 budgets.
    If the EPA were either to find adequate or to approve the post-
attainment milestone year budgets now, those budgets would have to be 
used in transportation conformity determinations that are made after 
the effective date of the adequacy finding or approval even if the San 
Joaquin Valley ultimately attains the PM2.5 NAAQS by the 
attainment date. This would mean that the San Joaquin Valley MPOs would 
be required to demonstrate conformity for the post-attainment date 
milestone year and all later years addressed in the conformity 
determination (e.g., the last year of the metropolitan transportation 
plan) to the post-attainment date RFP budgets rather than the budgets 
associated with the attainment year for the area (i.e., the budgets for 
2023). The EPA does not believe that it is necessary to demonstrate 
conformity using these post-attainment year budgets in areas that 
either the EPA anticipates will attain by the attainment date or in 
areas that attain by the attainment date.
    If the EPA determines that the San Joaquin Valley has failed to 
attain the 1997 annual PM2.5 NAAQS by the applicable 
attainment date, the EPA would begin the budget adequacy and approval 
processes under 40 CFR 93.118 for the 2026 post-attainment year budgets 
concurrent with such determination that the area failed to attain. If 
the EPA finds the 2026 budgets adequate or approves them, those budgets 
must then be used in subsequent transportation conformity 
determinations.\401\ The EPA believes that initiating the process to 
act on the submitted post-attainment year budgets concurrent with a 
determination that the area has failed to attain by the applicable 
attainment date ensures that transportation activities will not cause 
or contribute to new violations, increase the frequency or severity of 
any existing violations, or delay timely attainment or any required 
interim emissions reductions or milestones in the San Joaquin Valley 
PM2.5 nonattainment area, consistent with the requirements 
of CAA section 176(c)(1)(B).
---------------------------------------------------------------------------

    \401\ See 40 CFR 93.109(c).
---------------------------------------------------------------------------

    As noted above, the State included a trading mechanism to be used 
in transportation conformity analyses that would be used in conjunction 
with the budgets in the SJV PM2.5 Plan, as allowed for under 
40 CFR 93.124(b). This trading mechanism would allow MPOs to use future 
decreases in NOX emissions from on-road mobile sources to 
offset any on-road increases in PM2.5 emissions using a 6.5 
to 1 NOX to PM2.5 ratio in transportation 
conformity determinations for the 1997 annual PM2.5 NAAQS. 
To ensure that the trading mechanism does not affect the ability to 
meet the NOX budget, the Plan provides that the 
NOX emissions reductions available to supplement the 
PM2.5 budget would only be those remaining after the 
NOX budget has been met. The San Joaquin Valley MPOs will 
have to document clearly the calculations used in the trading when 
demonstrating conformity, along with any additional reductions of 
NOX and PM2.5 emissions in the conformity 
analysis. The trading calculations must be performed prior to the final 
rounding to demonstrate conformity with the budgets.
    The EPA has reviewed the trading mechanism as described on pages D-
125 to D-127 in Appendix D of the 15 [micro]g/m\3\ SIP Revision and 
finds it is appropriate for transportation conformity purposes in the 
San Joaquin Valley for the 1997 annual PM2.5 NAAQS. The 
methodology for estimating the trading ratio for conformity purposes is 
essentially an update (based on newer modeling) of the approach that 
the EPA previously approved for the 2008 PM2.5 Plan for the 
1997 PM2.5 NAAQS \402\ and the 2012 PM2.5 Plan 
for the 2006 24-hour PM2.5 NAAQS.\403\ The State's approach 
in the previous plans was to model the ambient PM2.5 effect 
of areawide NOX emissions reductions and of areawide direct 
PM2.5 emissions reductions, and to express the ratio of 
these modeled sensitivities as an inter-pollutant trading ratio.
---------------------------------------------------------------------------

    \402\ 80 FR 1816, 1841 (January 13, 2015) (noting the EPA's 
prior approval of budgets for the 1997 annual and 24-hour 
PM2.5 standards in the 2008 PM2.5 Plan at 76 
FR 69896).
    \403\ 81 FR 59876 (August 31, 2016).
---------------------------------------------------------------------------

    In the updated analysis for the SJV PM2.5 Plan, the 
State completed separate sensitivity analyses for the annual and 24-
hour NAAQS and modeled only transportation related sources in the 
nonattainment area. The ratio the State is proposing to use for 
transportation conformity purposes is derived from air quality modeling 
that evaluated the effect of reductions in transportation-related 
NOX and PM2.5 emissions in the San Joaquin Valley 
on ambient concentrations at the Bakersfield-California Avenue, 
Bakersfield-Planz, Fresno-Garland, and Fresno-Hamilton & Winery 
monitoring sites. The modeling that the State performed to evaluate the 
effectiveness of NOX and PM2.5 reductions on 
ambient annual concentrations showed NOX to PM2.5 
ratios that range from a high of 7.1 at the Bakersfield-Planz monitor 
to a low of 6.0 at the two Fresno monitors.\404\ In a recent action on 
the 2018 PM2.5 Plan for the 2012 annual PM2.5 
NAAQS, we found that the State's approach is a reasonable method to use 
to develop ratios for transportation conformity purposes and approved 
the 6.5 to 1 NOX to PM2.5 trading mechanism as an 
enforceable component of the transportation conformity program for the 
San Joaquin Valley for the 2012 PM2.5 NAAQS.\405\ Here, we 
similarly find that the State's approach is reasonable and propose to 
approve the 6.5 to 1 NOX for PM2.5 trading 
mechanism as enforceable components of the transportation conformity 
program for the San Joaquin Valley for

[[Page 45319]]

the 1997 annual PM2.5 NAAQS. If approved, this trading ratio 
will replace the 9 to 1 NOX to PM2.5 trading 
ratio approved for the San Joaquin Valley for analysis years after 2014 
for the 1997 annual PM2.5 NAAQS.\406\
---------------------------------------------------------------------------

    \404\ 15 [micro]g/m\3\ SIP Revision, Appendix D, p. D-126.
    \405\ See 86 FR 49100, 49128 (September 1, 2021) (proposed rule) 
and 86 FR 67343, 67346 (November 26, 2021) (final rule).
    \406\ 76 FR 69896.
---------------------------------------------------------------------------

G. Nonattainment New Source Review Requirements Under CAA Section 
189(e)

    Section 189(e) of the CAA specifically requires that the control 
requirements applicable to major stationary sources of direct 
PM2.5 also apply to major stationary sources of 
PM2.5 precursors, except where the Administrator determines 
that such sources do not contribute significantly to PM2.5 
levels that exceed the NAAQS in the area.\407\ The control requirements 
applicable to major stationary sources of direct PM2.5 in a 
Serious PM2.5 nonattainment area include, at minimum, the 
requirements of a nonattainment NSR permit program meeting the 
requirements of CAA sections 172(c)(5) and 189(b)(3). As part of our 
April 7, 2015 final action to reclassify the San Joaquin Valley area as 
Serious nonattainment for the 1997 PM2.5 standards, we 
established a May 7, 2016 deadline for the State to submit 
nonattainment NSR SIP revisions addressing the requirements of CAA 
sections 189(b)(3) and 189(e) of the Act for the 1997 PM2.5 
NAAQS.\408\
---------------------------------------------------------------------------

    \407\ General Preamble, 13539 and 13541-13542.
    \408\ 80 FR 18528, 18533.
---------------------------------------------------------------------------

    California submitted nonattainment NSR SIP revisions to address the 
subpart 4 requirements for the San Joaquin Valley Serious 
PM2.5 nonattainment area on November 20, 2019.\409\ On June 
28, 2023, the EPA finalized a limited approval and limited disapproval 
of the nonattainment NSR SIP revisions.\410\ We are not taking any 
further action on the submission at this time.
---------------------------------------------------------------------------

    \409\ Letter dated November 15, 2019, from Richard W. Corey, 
Executive Officer, CARB, to Michael Stoker, Regional Administrator, 
EPA Region IX.
    \410\ EPA Region IX, ``Air Plan Revisions; California; San 
Joaquin Valley Air Pollution Control District; Stationary Source 
Permits,'' final rule signed June 28, 2023.
---------------------------------------------------------------------------

V. Environmental Justice Considerations

    Executive Order 12898 requires that federal agencies, to the 
greatest extent practicable and permitted by law, identify and address 
disproportionately high and adverse human health or environmental 
effects of their actions on minority and low-income populations.\411\ 
Additionally, Executive Order 13985 directs federal government agencies 
to assess whether, and to what extent, their programs and policies 
perpetuate systemic barriers to opportunities and benefits for people 
of color and other underserved groups,\412\ and Executive Order 14008 
directs federal agencies to develop programs, policies, and activities 
to address the disproportionate health, environmental, economic, and 
climate impacts on disadvantaged communities.\413\
---------------------------------------------------------------------------

    \411\ 59 FR 7629 (February 16, 1994).
    \412\ 86 FR 7009 (January 25, 2021).
    \413\ 86 FR 7619 (February 1, 2021).
---------------------------------------------------------------------------

    To identify environmental burdens and susceptible populations in 
underserved communities in the San Joaquin Valley nonattainment area 
and to better understand the context of our proposed action on these 
communities, we rely on the EPA's August 2022 screening-level analysis 
for PM2.5 in the San Joaquin Valley using the EPA's 
environmental justice (EJ) screening and mapping tool 
(``EJSCREEN'').414 415 Maps showing census block level data 
for the San Joaquin Valley from EJSCREEN are included in the EPA's 1997 
Annual PM2.5 TSD. The results of this analysis are being 
provided for informational and transparency purposes.
---------------------------------------------------------------------------

    \414\ EJSCREEN provides a nationally consistent dataset and 
approach for combining environmental and demographic indicators. 
EJSCREEN is available at https://www.epa.gov/ejscreen/what-ejscreen. 
The EPA used EJSCREEN to obtain environmental and demographic 
indicators representing each of the eight counties in the San 
Joaquin Valley. We note that the indicators for Kern County are for 
the entire county. While the indicators might have slightly 
different numbers for the San Joaquin Valley portion of the county, 
most of the county's population is in the San Joaquin Valley 
portion, and thus the differences would be small. These indicators 
are included in EJSCREEN reports that are available in the 
rulemaking docket for this action.
    \415\ EPA Region IX, ``EJSCREEN Analysis for the Eight Counties 
of the San Joaquin Valley Nonattainment Area,'' August 2022.
---------------------------------------------------------------------------

    Our screening-level analysis indicates that the ``Demographic 
Index'' for each of the eight counties in the San Joaquin Valley is 
above the national average, ranging from 48 percent in Stanislaus 
County to 61 percent in Tulare County, compared to 36 percent 
nationally. The Demographic Index is the average of an area's percent 
minority and percent low income populations, i.e., the two populations 
explicitly named in Executive Order 12898.\416\ All eight counties are 
above the national average for demographic indices of ``Linguistically 
Isolated Population'' and ``Population with Less than High School 
Education.''
---------------------------------------------------------------------------

    \416\ EJSCREEN reports environmental indicators (e.g., air 
toxics cancer risk, Pb paint exposure, and traffic proximity and 
volume) and demographic indicators (e.g., people of color, low 
income, and linguistically isolated populations). The value for a 
particular indicator measures how the community of interest compares 
with the state, the EPA region, or the national average. For 
example, if a given location is at the 95th percentile nationwide, 
this means that only 5 percent of the U.S. population has a higher 
value than the average person in the location being analyzed. 
EJSCREEN also reports EJ indexes, which are combinations of a single 
environmental indicator with the EJSCREEN Demographic Index. For 
additional information about environmental and demographic 
indicators and EJ indexes reported by EJSCREEN, see EPA, ``EJSCREEN 
Environmental Justice Mapping and Screening Tool--EJSCREEN Technical 
Documentation,'' Section 2 (September 2019).
---------------------------------------------------------------------------

    With respect to pollution, all eight counties are at or above the 
97th percentile nationally for the PM2.5 index and seven of 
the eight counties in the San Joaquin Valley are at or above the 90th 
percentile nationally for the PM2.5 EJ index, which is a 
combination of the Demographic Index and the PM2.5 index. 
Most counties are also above the 80th percentile for each of 11 
additional EJ indices included in the EPA's EJSCREEN analysis. In 
addition, several counties are above the 90th percentile for certain EJ 
indices, including, for example, the Ozone EJ Index (Fresno, Kern, 
Madera, Merced, and Tulare counties), the National Air Toxics 
Assessment (NATA) Respiratory Hazard EJ Index (Madera and Tulare 
counties), and the Wastewater Discharge Indicator EJ Index (Merced, San 
Joaquin, Stanislaus, and Tulare counties).\417\
---------------------------------------------------------------------------

    \417\ Notably, Tulare County is above the 90th percentile for 6 
of the 12 EJ indices in the EPA's EJSCREEN analysis, including the 
PM2.5 EJ Index, which is the highest value among all San 
Joaquin Valley counties.
---------------------------------------------------------------------------

    This proposed action would approve the State's plan for attaining 
the 1997 annual PM2.5 NAAQS. Information on the 1997 annual 
PM2.5 NAAQS and its relationship to negative health impacts 
can be found at 62 FR 38652 (July 18, 1997). We expect that this action 
and resulting emissions reductions will generally be neutral or 
contribute to reduced environmental and health impacts on all 
populations in the San Joaquin Valley, including people of color and 
low-income populations. At a minimum, this action would not worsen 
existing air quality and is expected to ensure the area is meeting 
requirements to attain and/or maintain air quality standards. Further, 
there is no information in the record indicating that this action is 
expected to have disproportionately high or adverse human health or 
environmental effects on a particular group of people.

VI. CAA Section 110(a)(2)(E)(i) ``Necessary Assurances'' and Title VI 
of the Civil Rights Act of 1964

    As discussed in Section III of this proposal, a Serious area plan 
must meet the general requirements applicable to all SIP submissions 
under section 110 of

[[Page 45320]]

the CAA, including the requirement to provide necessary assurances that 
the implementing agencies have adequate personnel, funding, and 
authority under section 110(a)(2)(E). Section 110(a)(2)(E) of the CAA, 
in relevant part and with emphasis added, reads as follows:

    (2) Each implementation plan submitted by a State under this 
chapter shall be adopted by the State after reasonable notice and 
public hearing. Each such plan shall-- . . .
    (E) provide (i) necessary assurances that the State (or, except 
where the Administrator deems inappropriate, the general purpose 
local government or governments, or a regional agency designated by 
the State or general purpose local governments for such purpose) 
will have adequate personnel, funding, and authority under State 
(and, as appropriate, local) law to carry out such implementation 
plan (and is not prohibited by any provision of Federal or State law 
from carrying out such implementation plan or portion thereof), (ii) 
requirements that the State comply with the requirements respecting 
State boards under section 7428 of this title, and (iii) necessary 
assurances that, where the State has relied on a local or regional 
government, agency, or instrumentality for the implementation of any 
plan provision, the State has responsibility for ensuring adequate 
implementation of such plan provision.\418\
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    \418\ 42 U.S.C. 7410(a)(2)(E) (emphasis added).

    The EPA has previously addressed considerations regarding CAA 
section 110(a)(2)(E)(i) specifically as it regards Title VI of the 
Civil Rights Act of 1964 (Title VI) in prior SIP actions. In 2012, the 
EPA explained the following in a SIP action, in response to a comment 
---------------------------------------------------------------------------
regarding this provision:

    El Comit[eacute] asserts that California failed to provide a 
``demonstration'' that its proposed revisions are not prohibited by 
Title VI of the Civil Rights Act. Section 110(a)(2)(E), however, 
does not require a state to ``demonstrate'' it is not prohibited by 
Federal or State law from implementing its proposed SIP revision. 
Rather, this section requires a state to provide ``necessary 
assurances'' of this. Courts have given EPA ample discretion in 
deciding what assurances are ``necessary'' and have held that a 
general assurance or certification is sufficient. (``EPA is entitled 
to rely on a state's certification unless it is clear that the SIP 
violates state law and proof thereof . . . is presented to EPA.'' 
BCCA Appeal Group v. EPA, 355 F.3d 817, 830 fn 11 (5th Cir. 
2003)).\419\
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    \419\ 77 FR 65294, 65302 (October 26, 2012) (footnotes omitted).

    The EPA's position on CAA section 110(a)(2)(E)(i) was ultimately 
upheld by the Ninth Circuit Court of Appeals in a challenge to an EPA 
SIP action.\420\ In that decision, El Comit[eacute], the Ninth Circuit 
stated,
---------------------------------------------------------------------------

    \420\ El Comit[eacute] Para El Bienstar de Earlimart et al. (El 
Comit[eacute]) v. EPA, 786 F.3d 688 (9th Cir. 2015).

    El Comit[eacute]'s argument fails because it misconstrues the 
EPA's burden regarding the ``necessary assurances'' requirement. The 
EPA has a duty to provide a reasoned judgment as to whether the 
state has provided ``necessary assurances,'' but what assurances are 
``necessary'' is left to the EPA's discretion. NRDC, Project on 
Clean Air v. EPA, 478 F.2d 875, 890-91 (1st Cir.1973); see also 
Motor Vehicle Mfrs. Ass'n, 463 U.S. at 43, 103 S.Ct. 2856 (providing 
that an agency's decision is not arbitrary and capricious if it 
considered the relevant data and gave a satisfactory explanation for 
its action).\421\
---------------------------------------------------------------------------

    \421\ Id. at 700.

    What is appropriate for purposes of necessary assurances can vary 
depending upon the nature of the issues in a particular situation. 
Thus, the EPA evaluates a state's compliance with CAA 110(a)(2)(E)(i) 
on a case-by-case basis.
    For purposes of background context, Title VI prohibits recipients 
of federal financial assistance from discriminating on the basis of 
race, color, or national origin. Under the EPA's nondiscrimination 
regulations, which implement Title VI and other federal civil rights 
laws,\422\ recipients of EPA financial assistance are prohibited from 
taking actions in their programs or activities that are intentionally 
discriminatory and/or have an unjustified disparate impact.\423\ This 
includes policies, criteria, or methods of administering programs that 
are neutral on their face but have the effect of discriminating.\424\ 
Under the EPA's regulation, recipients of EPA financial assistance are 
also required to have in place certain procedural safeguards, including 
grievance procedures that assure the prompt and fair resolution of 
external discrimination complaints.\425\
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    \422\ 40 CFR. part 7 and part 5.
    \423\ 40 CFR 7.30 and 7.35.
    \424\ 40 CFR 7.35(b).
    \425\ 40 CFR 7.90.
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    The EPA carries out its mandate to ensure that recipients of EPA 
financial assistance comply with their nondiscrimination obligations by 
investigating administrative complaints filed with the EPA alleging 
discrimination prohibited by Title VI and the other federal civil 
rights laws; \426\ initiating affirmative compliance reviews; \427\ and 
providing technical assistance to recipients to assist them in meeting 
their Title VI obligations. The EPA notes that at the time of this 
proposal, no Title VI complaint has been filed against CARB or the 
District regarding the SJV PM2.5 Plan for the 1997 annual 
PM2.5 NAAQS. Also, the EPA (through the Office of External 
Civil Rights Compliance (OECRC)) has not initiated and is not currently 
conducting a compliance review of either CARB or SJVUAPCD.
---------------------------------------------------------------------------

    \426\ 40 CFR 7.120.
    \427\ 40 CFR 7.115.
---------------------------------------------------------------------------

    In a recent supplemental proposal on the San Joaquin Valley 
attainment plan for the 2012 annual PM2.5 NAAQS, the EPA 
acknowledged that it had not issued national guidance or regulations 
concerning implementation of section 110(a)(2)(E) as it pertains to 
consideration of Title VI in the context of the SIP program.\428\ While 
the EPA's work on this SIP-specific guidance is ongoing as of the time 
of this proposed action, there are resources of general applicability 
concerning Title VI obligations for recipients of federal financial 
assistance.\429\
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    \428\ 87 FR 60494, 60528-30 (October 5, 2022).
    \429\ See ECRCO's Toolkit Chapter I at: https://www.epa.gov/sites/default/files/2017-01/documents/toolkit-chapter1-transmittal_letter-faqs.pdf, January 18, 2017, and Department of 
Justice ``Title VI Legal Manual (Updated)'' at: https://www.justice.gov/crt/fcs/T6Manual6. See also, e.g., EPA, ``Guidance 
on Considering Environmental Justice During the Development of 
Regulatory Actions,'' (May 2015); EPA, ``Technical Guidance for 
Assessing Environmental Justice in Regulatory Analysis,'' (June 
2016); El Comite Para el Bienestar de Earlimart v. EPA, 786 F.3d 688 
(9th Cir. 2015); and S. Camden Citizens in Action v. New Jersey 
Dept. of Envtl. Prot., 145 F. Supp. 2d 446, 501 (D.N.J. 2001), 
opinion modified and supplemented, 145 F. Supp. 2d 505 (D.N.J. 
2001), rev'd, 274 F.3d 771 (3d Cir. 2001) (agency, as recipient of 
federal funding, had obligation under Title VI to consider racially 
disparate adverse impacts when determining whether to issue permit, 
in addition to applicant's compliance with applicable air quality 
standards).
---------------------------------------------------------------------------

State Submission

    On June 15, 2023, CARB submitted to the EPA supplemental 
information from CARB and the District (``Title VI Supplement'') in 
which the State outlines its consideration of Title VI in the context 
of SIP development in order to provide necessary assurances for 
purposes of CAA section 110(a)(2)(E)(i).\430\
---------------------------------------------------------------------------

    \430\ Letter dated June 15, 2023, from Steven S. Cliff, 
Executive Officer, CARB, to Martha Guzman, Regional Administrator, 
EPA Region IX, with enclosures titled ``Title VI of the Civil Rights 
Act of 1964: CARB Supplemental Information for EPA in Support of 15 
[micro]g/m\3\ Annual PM2.5 Standard'' (``CARB Title VI 
Supplement'') and ``San Joaquin Valley Air Pollution Control 
District Write-Up on Title VI of the Civil Rights Act of 1964: 
Supplemental Information for EPA in Support of 15 [micro]g/m\3\ 
Annual PM2.5 Standard'' (``District Title VI 
Supplement'').
---------------------------------------------------------------------------

    The State's Title VI Supplement discusses actions being taken 
locally and statewide by CARB and the California legislature. For 
example, the State's Title VI Supplement discusses California State 
Assembly Bill 617 (``AB 617''), a State law which requires community-
focused and community-driven action to reduce air pollution and improve 
public health in communities that experience

[[Page 45321]]

disproportionate burdens from exposure to air pollutants in California. 
CARB implements AB 617 through its Community Air Protection Program, 
which began implementation in 2018. As of February 2023, 19 communities 
have been selected to receive additional support and opportunities for 
outreach in developing and implementing actions for cleaner air in 
their communities, including four communities in the San Joaquin 
Valley.\431\ In addition, the Title VI Supplement points to development 
of community air monitoring networks to learn about local exposures and 
the development of a racial equity assessment lens to consider benefits 
and burdens of CARB programmatic work in the planning stages. The EPA 
acknowledges CARB's and the District's explanation that these types of 
actions result in engagement with the public in the communities 
affected by this SIP revision, which helps to provide necessary 
assurances as contemplated by section 110(a)(2)(E)(i).
---------------------------------------------------------------------------

    \431\ Id. at 5. The four San Joaquin Valley communities that 
have been selected into the Community Air Protection Program are 
South Central Fresno, Shafter, Stockton, and Arvin/Lamont.
---------------------------------------------------------------------------

    Specific to the SJV PM2.5 Plan for the 1997 annual 
PM2.5 NAAQS, the submission further describes the early and 
enhanced public engagement processes that CARB and the District 
undertook during the development and approval of the 2016 State SIP 
Strategy, Valley State SIP Strategy, 2018 PM2.5 Plan, and 15 
[micro]g/m\3\ SIP Revision, all of which formed the basis for the SJV 
PM2.5 Plan for the 1997 annual PM2.5 NAAQS. CARB 
notes that the State prioritized public participation and describes the 
numerous public meetings and workshops held in Sacramento, Fresno, and 
Bakersfield for community-based organizations and other stakeholders 
during the preparation of the SJV PM2.5 Plan and related 
control measures, including the Heavy-Duty I/M measure.\432\ CARB and 
the District also note that Plan documents were made available for 
public review 30 days prior to board consideration, and that board 
hearings and workshops offered simultaneous Spanish translation 
services and that interpretation in other languages was made available 
on request.\433\
---------------------------------------------------------------------------

    \432\ CARB Title VI Supplement, pp. 3-4.
    \433\ CARB Title VI Supplement, p. 3, and District Title VI 
Supplement.
---------------------------------------------------------------------------

    In addition to discussing the State's processes for public 
engagement during the development of the SJV PM2.5 Plan for 
the 1997 annual PM2.5 NAAQS, the State's Title VI Supplement 
also describes CARB's recent and ongoing efforts to develop and 
implement the 2022 State SIP Strategy.\434\ These efforts include 
soliciting public input on potential control measures through meetings 
with individual community-based organizations, workshops, and webinars, 
and publishing a list of the suggested measures from the public to seek 
additional input. Seve ral of the measures suggested by the public were 
ultimately adopted in the 2022 State SIP Strategy,\435\ and CARB notes 
that public processes will continue as each measure is developed, 
adopted, and implemented by the State.
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    \434\ CARB Title VI Supplement, pp. 4-6.
    \435\ These measures include a regulation developed in 
collaboration with the California Department of Pesticide Regulation 
to reduce VOC emissions from pesticides, and a measure to provide 
small trucking companies with access to zero-emission truck 
incentive funding.
---------------------------------------------------------------------------

    Finally, the State describes its written Civil Rights Policy and 
Discrimination Complaint process.\436\ CARB's Civil Rights Policy 
states in part:
---------------------------------------------------------------------------

    \436\ Id. at 6-8.

    It is the California Air Resources Board (CARB) policy to 
provide fair and equal access to the benefits of a program or 
activity administered by CARB. CARB will not tolerate discrimination 
against any person(s) seeking to participate in, or receive the 
---------------------------------------------------------------------------
benefits of, any program or activity offered or conducted by CARB.

    The state explains that through its Civil Rights Officer, CARB 
coordinates compliance efforts, receives inquiries concerning non-
discrimination requirements, and ensures the agency is complying with 
State and federal reporting and record retention requirements, 
including those required by CARB's Civil Rights Policy, Title VI, and 
40 CFR 7.10 et seq. CARB's Civil Rights Policy includes a process for 
filing a complaint of discrimination against CARB if an individual 
believes they were unlawfully denied full and equal access during the 
administration of the agency's programs and services offered to the 
public. A complaint must be filed within one year of the alleged 
discrimination with the potential for an extension of 90 days if the 
complainant first obtained knowledge of the facts of the alleged 
violation after the expiration of the one-year time limit.
    In this action, the EPA is proposing to find that the State has 
provided adequate necessary assurances for purposes of CAA section 
110(a)(2)(E)(i) for the SJV PM2.5 Plan for the 1997 annual 
PM2.5 NAAQS. The EPA's proposed SIP approval does not 
constitute a formal finding of compliance with Title VI or 40 CFR part 
7. The EPA did not conduct a full Title VI investigation or compliance 
review.\437\ Approval of this SIP submission for purposes of CAA 
110(a)(2)(E)(i) does not affect the EPA's discretion to enforce Title 
VI and/or the EPA's civil rights regulations. The EPA retains full 
authority to process complaints which may result in conducting a Title 
VI investigation or compliance review with respect to CARB and/or this 
SIP action. Nothing in this proposed action is intended to limit or 
impact the EPA's discretion regarding necessary assurances 
determinations in other SIP actions.
---------------------------------------------------------------------------

    \437\ As discussed in Section V of this proposal, the EPA 
conducted an analysis of environmental burdens and susceptible 
populations in underserved communities as part of this action. The 
EPA summarized the results of the EJSCREEN analysis in the EPA's 
1997 Annual PM2.5 TSD and in a worksheet included in the 
docket for this action (EPA Region IX, ``EJSCREEN Analysis for the 
Eight Counties of the San Joaquin Valley Nonattainment Area,'' 
August 2022).
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VII. Summary of Proposed Action and Request for Public Comment

    For the reasons discussed in this proposed rule, under CAA section 
110(k)(3), the EPA is proposing to approve portions of the SJV 
PM2.5 Plan submitted by California that pertain to the 1997 
annual PM2.5 NAAQS in the San Joaquin Valley nonattainment 
area as follows:
    (1) We are proposing to find that the 2013 base year emissions 
inventories continue to satisfy the requirements of CAA section 
172(c)(3) and 40 CFR 51.1008 for purposes of both the Serious area and 
the CAA section 189(d) attainment plans, and to find that the 
forecasted inventories for the years 2017, 2018, 2019, 2020, 2023, and 
2026 provide an adequate basis for the BACM, RFP, five percent, and 
modeled attainment demonstration analyses;
    (2) We are proposing to approve the following elements as meeting 
the Serious nonattainment area planning requirements:
    (a) the BACM/BACT demonstration as meeting the requirements of CAA 
section 189(b)(1)(B) and 40 CFR 51.1010(a);
    (b) the demonstration (including air quality modeling) that the 
Plan provides for attainment as expeditiously as practicable as meeting 
the requirements of CAA sections 179(d) and 189(b) and 40 CFR 
51.1011(b);
    (c) the RFP demonstration as meeting the requirements of CAA 
sections 172(c)(2) and 171(1) and 40 CFR 51.1012; and
    (d) the quantitative milestone demonstration as meeting the 
requirements of CAA section 189(c) and 40 CFR 51.1013;

[[Page 45322]]

    (3) We are proposing to approve the following elements as meeting 
the CAA section 189(d) planning requirements:
    (a) the BACM/BACT demonstration as meeting the requirements of CAA 
sections 189(a)(1)(C) \438\ and 189(b)(1)(B) and 40 CFR 51.1010(c);
---------------------------------------------------------------------------

    \438\ As discussed in Section III.B of this document, a section 
189(d) plan must address any outstanding Moderate or Serious area 
requirements that have not previously been approved. Because we have 
not previously approved a subpart 4 RACM demonstration for the San 
Joaquin Valley nonattainment area, we are also proposing to approve 
the BACM/BACT demonstration in the SJV PM2.5 Plan as 
meeting the subpart 4 RACM/RACT requirement for the area.
---------------------------------------------------------------------------

    (b) the demonstration that the Plan will, at a minimum, achieve an 
annual five percent reduction in emissions of NOX as meeting 
the requirements of CAA section 189(d) and 40 CFR 51.1010(c);
    (c) the demonstration (including air quality modeling) that the 
Plan provides for attainment as expeditiously as practicable as meeting 
the requirements of CAA sections 179(d) and 189(d) and 40 CFR 
51.1011(b);
    (d) the RFP demonstration as meeting the requirements of CAA 
sections 172(c)(2) and 171(1) and 40 CFR 51.1012; and
    (e) the quantitative milestone demonstration as meeting the 
requirements of CAA section 189(c) and 40 CFR 51.1013;
    (4) We are proposing to approve the motor vehicle emission budgets 
for 2020 and 2023 as shown in Table 8 of this proposed rule because 
they are derived from approvable RFP and attainment demonstrations and 
meet the requirements of CAA section 176(c) and 40 CFR part 93, subpart 
A; and
    (5) We are proposing to approve the trading mechanism provided for 
use in transportation conformity analyses for the 1997 annual 
PM2.5 NAAQS, in accordance with 40 CFR 93.124(b).
    As discussed in Section I.B of this document, on November 26, 2021, 
the EPA partially approved and partially disapproved portions of the 
2018 PM2.5 Plan that addressed attainment of the 1997 annual 
PM2.5 NAAQS in the San Joaquin Valley nonattainment area. 
The elements that the EPA disapproved include the attainment 
demonstration, comprehensive precursor demonstration, five percent 
annual emissions reductions demonstration, BACM demonstration, RFP 
demonstration, quantitative milestones, motor vehicle emission budgets, 
and contingency measures. This disapproval was effective on December 
27, 2021. Also effective December 27, 2021, the EPA disapproved the 
contingency measure element of the 2018 PM2.5 Plan as it 
relates to the requirements for the Serious area plan 2006 24-hour 
PM2.5 NAAQS and the Moderate area plan for the 2012 annual 
PM2.5 NAAQS.\439\ In our November 26, 2021 final 
disapprovals, we noted that offset and highway sanctions under CAA 
sections 179(b)(2) and 179(b)(1), respectively, would not apply if 
California submits, and we approve, a SIP submission that corrects all 
of the deficiencies identified in our final actions prior to the 
imposition of sanctions.\440\ This proposed approval, if finalized, 
would remedy several but not all of the deficiencies because this 
action does not address the prior disapprovals of the contingency 
measure requirements for the 1997 annual PM2.5 NAAQS, 2006 
24-hour PM2.5 NAAQS, and 2012 annual PM2.5 NAAQS. 
Therefore, the sanctions will apply in the San Joaquin Valley as 
outlined in the November 26, 2021 final disapprovals unless or until 
California submits, and we approve, a SIP submission or submissions 
meeting the outstanding contingency measure requirements for these 
NAAQS.
---------------------------------------------------------------------------

    \439\ 86 FR 67343.
    \440\ 86 FR 67329.
---------------------------------------------------------------------------

    The EPA is soliciting public comments on the issues discussed in 
this proposed rule. We will accept comments from the public on this 
proposal for the next 30 days.

VIII. Statutory and Executive Order Reviews

    Under the CAA, the Administrator is required to approve a SIP 
submission that complies with the provisions of the CAA 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 CAA. Accordingly, this 
action merely approves state law as meeting Federal requirements and 
does not impose additional requirements beyond those imposed by state 
law. For that reason, this action:
     Is not a significant regulatory action subject to review 
by the Office of Management and Budget under Executive Orders 12866 (58 
FR 51735, October 4, 1993) and 13563 (76 FR 3821, January 21, 2011);
     Does not impose an information collection burden under the 
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
     Is certified as not having a significant economic impact 
on a substantial number of small entities under the Regulatory 
Flexibility Act (5 U.S.C. 601 et seq.);
     Does not contain any unfunded mandate or significantly or 
uniquely affect small governments, as described in the Unfunded 
Mandates Reform Act of 1995 (Pub. L. 104-4);
     Does not have federalism implications as specified in 
Executive Order 13132 (64 FR 43255, August 10, 1999);
     Is not an economically significant regulatory action based 
on health or safety risks subject to Executive Order 13045 (62 FR 
19885, April 23, 1997);
     Is not a significant regulatory action subject to 
Executive Order 13211 (66 FR 28355, May 22, 2001); 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 CAA;
    In addition, the SIP is not approved to apply on any Indian 
reservation land or in any other area where the EPA or an Indian tribe 
has demonstrated that a tribe has jurisdiction. In those areas of 
Indian country, the rule does not have tribal implications and will not 
impose substantial direct costs on tribal governments or preempt tribal 
law as specified by Executive Order 13175 (65 FR 67249, November 9, 
2000).
    Executive Order 12898 (Federal Actions To Address Environmental 
Justice in Minority Populations and Low-Income Populations, 59 FR 7629, 
Feb. 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 SJVUAPCD 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. The EPA 
performed an environmental justice analysis, as is described above in 
the section titled,

[[Page 45323]]

``Environmental Justice Considerations.'' The analysis was done for the 
purpose of providing additional context and information about this 
rulemaking to the public, not as a basis of the action. Due to the 
nature of the action being taken here, this action is expected to have 
a neutral to positive impact on the air quality of the affected area. 
In addition, there is no information in the record upon which this 
decision is based inconsistent with the stated goal of E.O. 12898 of 
achieving 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, Ammonia, 
Incorporation by reference, Intergovernmental relations, Nitrogen 
dioxide, Particulate matter, Reporting and recordkeeping requirements, 
Sulfur dioxide, Volatile organic compounds.

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

    Dated: July 5, 2023.
Martha Guzman Aceves,
Regional Administrator, Region IX.
[FR Doc. 2023-14687 Filed 7-13-23; 8:45 am]
BILLING CODE 6560-50-P