[Federal Register Volume 86, Number 247 (Wednesday, December 29, 2021)]
[Proposed Rules]
[Pages 74310-74352]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-27796]



[[Page 74309]]

Vol. 86

Wednesday,

No. 247

December 29, 2021

Part IV





Environmental Protection Agency





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40 CFR Part 52





Clean Air Plans; 2012 Fine Particulate Matter Serious Nonattainment 
Area Requirements; San Joaquin Valley, California; Proposed Rule

Federal Register / Vol. 86 , No. 247 / Wednesday, December 29, 2021 / 
Proposed Rules

[[Page 74310]]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R09-OAR-2021-0884; FRL-9292-01-R9]


Clean Air Plans; 2012 Fine Particulate Matter Serious 
Nonattainment Area Requirements; San Joaquin Valley, California

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA or ``Agency'') 
proposes to approve portions of two state implementation plan (SIP) 
revisions submitted by the State of California to meet Clean Air Act 
(CAA or ``Act'') requirements for the 2012 annual fine particulate 
matter (PM2.5) national ambient air quality standards (NAAQS 
or ``standards'') in the San Joaquin Valley (SJV) Serious nonattainment 
area. Specifically, the EPA proposes to approve the State's Serious 
area plan for the 2012 annual PM2.5 NAAQS, submitted May 10, 
2019, for all Serious PM2.5 area requirements (except 
contingency measures), including emissions inventories, best available 
control measures, demonstrations of attainment and reasonable further 
progress, quantitative milestones, and motor vehicle emission budgets. 
We may, however, reconsider this proposal if, based on new information 
or public comments, we find that the State has not satisfied the 
statutory criteria for a Serious area PM2.5 attainment plan. 
The EPA also proposes to disapprove the portions of the State's Serious 
area plan, and the contingency provisions of a third SIP submission 
regarding residential wood burning, that pertain to the Serious area 
contingency measurement requirements for the 2012 annual 
PM2.5 NAAQS.

DATES: Any comments must arrive by January 28, 2022.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R09-
OAR-2021-0884, at https://www.regulations.gov. For comments submitted 
at Regulations.gov, follow the online instructions for submitting 
comments. Once submitted, comments cannot be edited or removed from 
Regulations.gov. The EPA may publish any comment received to its public 
docket. Do not submit electronically any information you consider to be 
Confidential Business Information (CBI) or other information whose 
disclosure is restricted by statute. Multimedia submissions (audio, 
video, etc.) must be accompanied by a written comment. The written 
comment is considered the official comment and should include 
discussion of all points you wish to make. The EPA will generally not 
consider comments or comment contents located outside of the primary 
submission (i.e., on the web, cloud, or other file sharing system). For 
additional submission methods, please contact the person identified in 
the FOR FURTHER INFORMATION CONTACT section. For the full EPA public 
comment policy, information about CBI or multimedia submissions, and 
general guidance on making effective comments, please visit https://www.epa.gov/dockets/commenting-epa-dockets.

FOR FURTHER INFORMATION CONTACT: Rory Mays, Air Planning Office (AIR-
2), EPA Region IX, (415) 972-3227, [email protected].

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

Table of Contents

I. Background for Proposed Action
II. Summary and Completeness Review of Applicable SIP Submissions
    A. San Joaquin Valley 2018 PM2.5 Plan
    B. Valley State SIP Strategy
    C. Rule 4901 Contingency Provision
III. Clean Air Act Requirements for PM2.5 Serious Area 
Plans
IV. Review of the San Joaquin Valley PM2.5 Serious Area 
Plan
    A. Emissions Inventory
    B. PM2.5 Precursors
    C. Air Quality Modeling
    D. Best Available Control Measures
    E. Nonattainment New Source Review Requirements Under CAA 
Section 189(e)
    F. Attainment Demonstration
    G. Reasonable Further Progress and Quantitative Milestones
    H. Contingency Measures
    I. Motor Vehicle Emission Budgets
V. Summary of Proposed Actions and Request for Public Comment
VI. Statutory and Executive Order Reviews

I. Background for Proposed Action

    On January 15, 2013, the EPA strengthened the primary annual NAAQS 
for particulate matter with a diameter of 2.5 microns or less 
(PM2.5) by lowering the level from 15.0 micrograms per cubic 
meter ([micro]g/m\3\) to 12.0 [micro]g/m\3\ (``2012 annual 
PM2.5 NAAQS'').\1\ The EPA established these standards after 
considering substantial evidence from numerous health studies 
demonstrating that serious health effects are associated with exposures 
to PM2.5 concentrations above these levels.
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    \1\ 78 FR 3086 and 40 CFR 50.18. The EPA first established NAAQS 
for PM2.5 on July 18, 1997 (62 FR 38652), including 
annual standards of 15.0 [micro]g/m\3\ based on a 3-year average of 
annual mean concentrations and 24-hour (daily) standards of 65 
[micro]g/m\3\ based on a 3-year average of 98th percentile 24-hour 
concentrations (40 CFR 50.7) (``1997 PM2.5 NAAQS''). In 
addition, on October 17, 2006, the EPA strengthened the 24-hour 
(daily) NAAQS for PM2.5 by lowering the level from 65 
[micro]g/m\3\ to 35 [micro]g/m\3\ (``2006 24-hour PM2.5 
NAAQS''). 71 FR 61144 and 40 CFR 50.13. Unless otherwise noted, all 
references to the PM2.5 standards in this notice, 
including all instances of ``2012 annual PM2.5 NAAQS,'' 
are to the 2012 primary annual NAAQS of 12.0 [micro]g/m\3\ codified 
at 40 CFR 50.18.
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    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 days), changes in lung function, and increased respiratory 
symptoms. Individuals particularly sensitive to PM2.5 
exposure include older adults, people with heart and lung disease, and 
children.\2\ Sources can emit PM2.5 directly into the 
atmosphere as a solid or liquid particle (``primary PM2.5'' 
or ``direct PM2.5'') or it can form in the atmosphere 
(``secondary PM2.5'') as a result of various chemical 
reactions among precursor pollutants such as nitrogen oxides 
(NOX), sulfur oxides (SOX), volatile organic 
compounds (VOC), and ammonia (NH3).\3\
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    \2\ 78 FR 3086, 3088.
    \3\ 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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    Following promulgation of a new or revised NAAQS, the EPA is 
required by CAA section 107(d) to designate areas throughout the nation 
as attaining or not attaining the NAAQS. On January 15, 2015, the EPA 
designated and classified the SJV as Moderate nonattainment for the 
2012 annual PM2.5 NAAQS.\4\ The EPA has approved the State's 
demonstration that it was impracticable to attain the 2012 annual 
PM2.5 NAAQS by the outermost December 31, 2021 Moderate area 
attainment date and related plan elements addressing the Moderate area 
requirements for the 2012 annual PM2.5 NAAQS, except for the 
contingency measure element, which the EPA disapproved.\5\ In that same 
action, the EPA reclassified the SJV as a Serious nonattainment area 
for these NAAQS.
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    \4\ 80 FR 2206 (codified at 40 CFR 81.305).
    \5\ 86 FR 67343 (November 26, 2021).
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    On December 27, 2021, the effective date of the SJV's 
reclassification as a Serious PM2.5 nonattainment area, the 
SJV will become subject to a new statutory attainment date no later 
than the end of the tenth calendar year following designation (i.e., 
December

[[Page 74311]]

31, 2025) and the requirement to submit a Serious area plan satisfying 
the requirements of CAA Title I, part D, including the requirements of 
subpart 4, for the 2012 annual PM2.5 NAAQS.\6\ As explained 
in the EPA's final reclassification action, the Serious area plan for 
the SJV must include, among other things, provisions to assure that, 
under CAA section 189(b)(1)(B), the best available control measures 
(BACM) for the control of direct PM2.5 and PM2.5 
precursors shall be implemented no later than four years after the area 
is reclassified and a demonstration (including air quality modeling) 
that the plan provides for attainment 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). As 
described in our final action reclassifying the SJV as a Serious 
PM2.5 nonattainment area, California must adopt and submit a 
SIP submission addressing the Serious nonattainment area requirements 
for the 2012 annual PM2.5 NAAQS within 18 months (i.e., by 
June 27, 2023), for emissions inventories, BACM, and nonattainment new 
source review (NSR), and by December 31, 2023, for the attainment 
demonstration and related planning requirements.
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    \6\ Id. at 67347.
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    The SJV 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.\7\ The area is home to four million people and is the 
nation's leading agricultural region. 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. The CAA assigns primary 
responsibility to the state for developing plans to attain the NAAQS. 
Under State law, California divides this responsibility between the San 
Joaquin Valley Unified Air Pollution Control District (SJVUAPCD or 
District) and the California Air Resources Board (CARB) in preparing 
attainment plans. Authority for regulating sources under state 
jurisdiction in the SJV is split 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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    \7\ For a precise description of the geographic boundaries of 
the SJV PM2.5 nonattainment area, see 40 CFR 81.305.
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II. Summary and Completeness Review of Applicable SIP Submissions

    The EPA is proposing action on portions of three SIP revisions 
submitted by CARB to meet the Serious nonattainment area requirements 
for the 2012 annual PM2.5 NAAQS in the SJV. Specifically, 
the EPA is proposing to act on those portions of the following two plan 
submissions that pertain to the Serious area requirements for the 2012 
annual PM2.5 NAAQS: 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''); \8\ and the ``San Joaquin Valley Supplement to the 2016 State 
Strategy for the State Implementation Plan,'' adopted by CARB on 
October 25, 2018 (``Valley State SIP Strategy'').
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    \8\ The 2018 PM2.5 Plan was developed jointly by CARB 
and the District.
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    We refer to the relevant portions of these SIP submissions 
collectively in this proposal as the ``SJV PM2.5 Plan'' or 
``Plan.'' The SJV PM2.5 Plan addresses attainment plan 
requirements for multiple PM2.5 NAAQS in the SJV, including 
the Serious area attainment plan requirements for the 2012 annual 
PM2.5 NAAQS. CARB submitted the SJV PM2.5 Plan to 
the EPA as a revision to the California SIP on May 10, 2019.\9\ It 
became complete by operation of law on November 10, 2019.\10\
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    \9\ Letter dated May 9, 2019, from Richard W. Corey, Executive 
Officer, CARB, to Mike Stoker, Regional Administrator, EPA Region 
IX. Previously, in separate rulemakings, the EPA has finalized 
action on the portions of the SJV PM2.5 Plan that pertain 
to the 1997 annual PM2.5 NAAQS, the 2006 24-hour 
PM2.5 NAAQS, and the Moderate area plan for the 2012 
annual PM2.5 NAAQS. See 86 FR 67329 (November 26, 2021) 
(final rule regarding the 1997 annual PM2.5 NAAQS); 85 FR 
44192 (July 22, 2020) (final rule regarding the 2006 24-hour 
PM2.5 NAAQS, except contingency measures); and 86 FR 
67343 (final rule regarding the Moderate area plan for the 2012 
annual PM2.5 NAAQS and contingency measures for the 2006 
24-hour PM2.5 NAAQS). The EPA has also separately 
proposed action on the portions of the SJV PM2.5 Plan 
that pertain to the 1997 24-hour PM2.5 NAAQS. 86 FR 53150 
(September 24, 2021).
    \10\ We note that, with respect to plans previously required for 
the 1997, 2006, and 2012 PM2.5 NAAQS, including the 
Moderate area plan only for the 2012 annual PM2.5 NAAQS, 
the EPA had made findings of failure to submit effective January 7, 
2019, that triggered sanctions clocks. 83 FR 62720 (December 6, 
2018). Following the May 10, 2019 submission of the 2018 
PM2.5 Plan and Valley State SIP Strategy, the EPA 
affirmatively determined that the SIP submissions addressed the 
deficiency that was the basis for such findings, resulting in the 
termination of the associated sanctions clocks. Letter dated June 
24, 2020, from Elizabeth Adams, Director, Air and Radiation 
Division, EPA Region IX, to Richard W. Corey, Executive Officer, 
CARB. However, neither the findings nor completeness determination 
applied to the Serious area plan for the 2012 annual 
PM2.5 NAAQS as it was not yet required.
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    In addition, the EPA is proposing action on the portion of a third 
SIP submission that pertains to SJVUAPCD Rule 4901, as amended by the 
District on June 20, 2019, and submitted to the EPA on July 19, 2019 
(``Rule 4901 Contingency Provision''). The EPA has already taken final 
action on the rule modification for this submission.\11\ In this action 
we are evaluating the submission for purposes of addressing the 
contingency measures requirement in the SJV for the 2012 annual 
PM2.5 NAAQS.
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    \11\ 85 FR 44206 (July 22, 2020) (final approval of District 
Rule 4901); 85 FR 1131, 1132-33 (January 9, 2020) (proposed approval 
of District Rule 4901). Completeness review for this submission was 
conducted and described in that action. See also 86 FR 67329 
(removing the contingency provision from the SIP).
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    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 adequate public notice was given and that an opportunity 
for a public hearing was provided consistent with the EPA's 
implementing regulations in 40 CFR 51.102.
    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.

A. San Joaquin Valley 2018 PM2.5 Plan

    The following portions of the 2018 PM2.5 Plan and 
related support documents address the Serious area requirements for the 
2012 annual PM2.5 NAAQS in the SJV: (i) Chapter 4 
(``Attainment Strategy for PM2.5''); (ii) Chapter 7 
(``Demonstration of Federal Requirements for the 2012 PM2.5 
Standard''); \12\ (iii) numerous appendices to the 2018 
PM2.5 Plan; (iv) 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 (``CARB

[[Page 74312]]

Staff Report''); \13\ and (v) 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).\14\ The 
SJVUAPCD Governing Board Resolution 18-11-16 includes emission 
reduction commitments on which the SJV PM2.5 Plan 
relies.\15\
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    \12\ Chapter 5 (``Demonstration of Federal Requirements for the 
1997 PM2.5 Standard'') and Chapter 6 (``Demonstration of 
Federal Requirements for the 2006 PM2.5 Standard'') of 
the 2018 PM2.5 Plan pertain to the 1997 PM2.5 
NAAQS and 2006 24-hour PM2.5 NAAQS, respectively.
    \13\ The CARB Staff Report includes CARB's review of, among 
other things, the 2018 PM2.5 Plan's control strategy and 
attainment demonstration. Letter dated December 11, 2019, from 
Richard W. Corey, Executive Officer, CARB to Mike Stoker, Regional 
Administrator, EPA Region IX, transmitting the CARB Staff Report.
    \14\ 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.
    \15\ SJVUAPCD Governing Board Resolution 18-11-16, paragraph 6, 
10-11.
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    The appendices to the 2018 PM2.5 Plan, in order of their 
evaluation in this proposed rule, include: (i) App. B (``Emissions 
Inventory''); (ii) App. A (``Ambient PM2.5 Data Analysis''); 
(iii) a plan precursor demonstration and clarifications, including App. 
G (``Precursor Demonstration'') and Attachment A (``Clarifying 
information for the San Joaquin Valley 2018 Plan regarding model 
sensitivity related to ammonia and ammonia controls'') to the CARB 
Staff Report; (iv) control strategy appendices, including App. C 
(``Stationary Source Control Measure Analyses''), App. D (``Mobile 
Source Control Measures Analyses''), and App. E (``Incentive-Based 
Strategy''); (v) modeling appendices, including App. J (``Modeling 
Emission Inventory''), App. K (``Modeling Attainment Demonstration''), 
and App. L (``Modeling Protocol''); (vi) App. H (``RFP, Quantitative 
Milestones, and Contingency''); and (vii) App. I (``New Source Review 
and Emission Reduction Credits''). The 2018 PM2.5 Plan 
addresses motor vehicle emission budget requirements in the 
``Transportation Conformity'' section of App. D (pages D-119 to D-131). 
The 2018 PM2.5 Plan also includes an Executive Summary, 
Introduction (Ch. 1), chapters on ``Air Quality Challenges and Trends'' 
(Ch. 2) and ``Health Impacts and Health Risk Reduction Strategy'' (Ch. 
3), and an appendix on ``Public Education and Technology Advancement'' 
(App. F).
    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.\16\ 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.\17\ The SIP 
submission includes proof of publication of notices for the respective 
public hearings. It also includes copies of the written and oral 
comments received during the State's and District's public review 
processes and the agencies' responses thereto.\18\ Therefore, we 
reaffirm that the 2018 PM2.5 Plan meets the procedural 
requirements for public notice and hearing in CAA sections 110(a) and 
110(l) and 40 CFR 51.102. The 2018 PM2.5 Plan became 
complete by operation of law on November 10, 2019, pursuant to CAA 
section 110(k)(1)(B).
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    \16\ 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.
    \17\ 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.
    \18\ 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, App. M (``Summary of Significant 
Comments and Responses'').
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B. Valley State SIP Strategy

    CARB developed the ``Revised Proposed 2016 State Strategy for the 
State Implementation Plan'' (``2016 State Strategy'') to support 
attainment planning in the SJV and Los Angeles-South Coast Air Basin 
(``South Coast'') ozone nonattainment areas.\19\ In its resolution 
adopting the 2016 State Strategy (CARB Resolution 17-7), the Board 
found that the 2016 State Strategy would achieve 6 tons per day (tpd) 
of NOX emission reductions and 0.1 tpd of direct 
PM2.5 emission reductions in the SJV by 2025 from source 
categories under the regulatory authority of CARB. The resolution 
directed CARB staff to work with the SJVUAPCD to identify additional 
reductions from sources under District regulatory authority as part of 
a comprehensive plan to attain all of the PM2.5 NAAQS for 
the SJV and to return to the Board with a commitment to achieve 
additional emission reductions from mobile sources.\20\
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    \19\ The EPA has approved certain commitments made by CARB in 
the 2016 State Strategy for purposes of attaining the ozone NAAQS in 
the SJV and South Coast ozone nonattainment areas. See, e.g., 84 FR 
3302 (February 12, 2019) and 84 FR 52005 (October 1, 2019).
    \20\ CARB Resolution 17-7, ``2016 State Strategy for the State 
Implementation Plan,'' March 23, 2017, 6-7.
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    CARB responded to this resolution by developing and adopting the 
``San Joaquin Valley Supplement to the 2016 State Strategy for the 
State Implementation Plan'' (``Valley State SIP Strategy'') to support 
the 2018 PM2.5 Plan. The State's May 10, 2019 SIP submission 
incorporates by reference the Valley State SIP Strategy as adopted by 
CARB on October 25, 2018, and submitted to the EPA on November 16, 
2018.\21\
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    \21\ Letter dated May 9, 2019, from Richard W. Corey, Executive 
Officer, CARB, to Mike Stoker, Regional Administrator, EPA Region 
IX, 2.
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    The Valley State SIP Strategy includes an Introduction (Ch. 1), a 
chapter on ``Measures'' (Ch. 2), and a ``Supplemental State Commitment 
from the Proposed State Measures for the Valley'' (Ch. 3). Much of the 
content of the Valley State SIP Strategy is reproduced in Chapter 4 
(``Attainment Strategy for PM2.5'') of the 2018 
PM2.5 Plan.\22\ The Valley State SIP Strategy also includes 
CARB Resolution 18-49, which, among other things, commits CARB to 
achieve specific amounts of NOX and PM2.5 
emission reductions by specific years, for purposes of attaining the 
PM2.5 NAAQS in the SJV.\23\
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    \22\ For example, Table 2 (proposed mobile source measures and 
schedule), Table 3 (emissions reductions from proposed mobile source 
measures), and Table 4 (summary of emission reduction measures) of 
the Valley State SIP Strategy correspond to tables 4-8, 4-9, and 4-
7, respectively, of the 2018 PM2.5 Plan, Chapter 4.
    \23\ CARB Resolution 18-49, ``San Joaquin Valley Supplement to 
the 2016 State Strategy for the State Implementation Plan,'' October 
25, 2018, 5.
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    CARB provided the required public notice and opportunity for public 
comment prior to its October 25, 2018 public hearing on and adoption of 
the Valley State SIP Strategy.\24\ The SIP submission includes proof of 
publication of the public notice for this public hearing. It also 
includes copies of the written and oral comments received during the 
State's public review process and CARB's responses thereto.\25\ 
Therefore, we reaffirm that the Valley State SIP Strategy meets the 
procedural requirements for public notice and hearing in CAA sections 
110(a) and 110(l) and 40 CFR 51.102. The Valley State SIP Strategy 
became complete by operation of law on November 10, 2019, pursuant to 
CAA section 110(k)(1)(B).
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    \24\ CARB, ``Notice of Public Meeting to Consider the San 
Joaquin Valley Supplement to the 2016 State Strategy for the State 
Implementation Plan,'' September 21, 2018, and CARB Resolution 18-
49.
    \25\ CARB, ``Board Meeting Comments Log,'' November 2, 2018 and 
compilation of written comments; and J&K Court Reporting, LLC, 
``Meeting, State of California Air Resources Board,'' October 25, 
2018 (transcript of CARB's public hearing).
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C. Rule 4901 Contingency Provision

    Lastly, the 2018 PM2.5 Plan addresses the contingency 
measure requirements for the 2012 annual PM2.5 NAAQS by 
reference to, among other things, a District contingency measure, and

[[Page 74313]]

emissions estimates for the year following the attainment year for use 
in evaluating whether the emissions reductions from the contingency 
measure are sufficient.\26\ With respect to the District contingency 
measure, the 2018 PM2.5 Plan calls for the District to amend 
District Rule 4901 (``Wood Burning Fireplaces and Wood Burning 
Heaters'') to include a provision in the rule with a trigger that would 
activate the requirements of the contingency measure should the EPA 
issue a determination or final rulemaking that the SJV failed to meet a 
regulatory requirement necessitating implementation of a contingency 
measure.
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    \26\ 2018 PM2.5 Plan, App. H (revised February 11, 
2020), H-24 to H-26.
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    In response to the commitment made in the 2018 PM2.5 
Plan, in June 2019 the District adopted amendments to Rule 4901, 
including a new provision (codified as section 5.7.3 of the amended 
rule) that is structured to function as a contingency measure. On July 
19, 2019, CARB submitted the amended rule to the EPA for approval.\27\ 
The EPA took final action to approve the amended Rule 4901 (including 
the new section 5.7.3) into the California SIP, but in our approval we 
noted that we were not evaluating the contingency measure in section 
5.7.3 of revised Rule 4901 for compliance with all requirements of the 
CAA and the EPA's implementing regulations that apply to such 
measures.\28\ Rather, we approved the new provision (section 5.7.3) 
into the SIP as part of our approval of the entire amended rule as SIP 
strengthening because the provision strengthens the rule by providing a 
possibility of additional curtailment days and thus potentially 
additional emissions reductions. We indicated that we would evaluate 
whether section 5.7.3, in conjunction with other submitted provisions, 
meets the statutory and regulatory requirements for contingency 
measures in a future action.\29\ In this document, we are evaluating 
District Rule 4901, and in particular section 5.7.3, in the context of 
our action on the contingency measure element in the 2018 
PM2.5 Plan for the 2012 annual PM2.5 NAAQS.
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    \27\ Letter dated July 19, 2019, from Richard W. Corey, 
Executive Officer, CARB, to Mike Stoker, Regional Administrator, EPA 
Region IX.
    \28\ 85 FR 44206 (July 22, 2020) (final approval of District 
Rule 4901); 85 FR 1131, 1132-33 (January 9, 2020) (proposed approval 
of District Rule 4901).
    \29\ The EPA subsequently removed section 5.7.3 of Rule 4901 
from the California SIP. 86 FR 67329 (final rule on 1997 annual 
PM2.5 NAAQS portion of the SJV PM2.5 Plan, 
including final disapproval of the contingency measures element for 
those NAAQS).
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III. Clean Air Act 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: \30\
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    \30\ 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 the best available control measures 
(BACM), including best available control technology (BACT), for the 
control of direct PM2.5 and all 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, 2025, for the SJV for the 2012 
annual PM2.5 NAAQS) (CAA sections 188(c)(2) and 
189(b)(1)(A)(i));
    (4) Plan provisions that require reasonable further progress (RFP) 
(CAA section 172(c)(2));
    (5) Quantitative milestones which are to be achieved every three 
years until the area is redesignated attainment and which 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'' \31\ thresholds 
from 100 tons per year (tpy) to 70 tpy (CAA section 189(b)(3)).
---------------------------------------------------------------------------

    \31\ 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).
---------------------------------------------------------------------------

    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 state's 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).
    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''); \32\ (2) ``State 
Implementation Plans; General Preamble for the Implementation of Title 
I of the Clean Air Act Amendments of 1990; Supplemental'' (``General 
Preamble Supplement''); \33\ 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'').\34\ 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 standards.\35\ We discuss these 
regulatory requirements and interpretations of the Act as appropriate 
in our evaluation of the State's submissions below.
---------------------------------------------------------------------------

    \32\ 57 FR 13498 (April 16, 1992).
    \33\ 57 FR 18070 (April 28, 1992).
    \34\ 59 FR 41998 (August 16, 1994).
    \35\ 81 FR 58010.

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[[Page 74314]]

IV. Review of the San Joaquin Valley PM2.5 Serious Area Plan

A. Emissions Inventory

1. Requirements for Emissions Inventories
    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, including Serious area 
requirements, in the PM2.5 SIP Requirements Rule and 
codified these requirements in 40 CFR 51.1008.\36\ The EPA has also 
issued guidance concerning emissions inventories for PM2.5 
nonattainment areas.\37\
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    \36\ Id. at 58078-58079.
    \37\ EPA, ``Emissions Inventory Guidance for Implementation of 
Ozone and Particulate Matter National Ambient Air Quality Standards 
(NAAQS) and Regional Haze Regulations,'' 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 should 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,\38\ and emissions of all chemical 
precursors to the formation of secondary PM2.5: Nitrogen 
oxides (NOX), sulfur dioxide (SO2), volatile 
organic compounds (VOC), and ammonia (NH3).\39\ In addition, 
the emissions inventory base year for a Serious PM2.5 
nonattainment area must be one of the three years for which monitored 
data were used to reclassify the area to Serious, or another 
technically appropriate year justified by the state in its Serious area 
plan submission.\40\
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    \38\ The Emissions Inventory Guidance identifies the types of 
sources for which the EPA expects states to provide condensable PM 
emission inventories. Emissions Inventory Guidance, section 4.2.1 
(``Condensable PM Emissions''), 63-65.
    \39\ 40 CFR 51.1008.
    \40\ 40 CFR 51.1008(b)(1).
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    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 it developed the submission. 
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 SJV PM2.5 Plan was 
EMFAC2014.\41\ Following CARB's submission of the Plan, the EPA 
approved EMFAC2017, the latest revision to this motor vehicle emissions 
model for SIP purposes.\42\ States are also required to use the EPA's 
``Compilation of Air Pollutant Emission Factors'' (``AP-42'') road dust 
method for calculating re-entrained road dust emissions from paved 
roads.\43\
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    \41\ 80 FR 77337 (December 14, 2015). EMFAC is short for 
EMission FACtor. The EPA announced the availability of the EMFAC2014 
motor vehicle emissions model, effective on the date of publication 
in the Federal Register, for use in state implementation plan 
development and transportation conformity in California. We note 
that CARB's use of EMFAC2014 in developing the emission inventories 
for the Serious area plan for the 2012 annual PM2.5 NAAQS 
preceded the requirement to adopt and submit such Serious area plan.
    \42\ 84 FR 41717 (August 15, 2019).
    \43\ 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 emission tests 
results. 76 FR 6328 (February 4, 2011). CARB used the revised 2011 
AP-42 methodology in developing on-road mobile source emissions. 
``Miscellaneous Process Methodology 7.9 Entrained Road Travel, Paved 
Road Dust,'' CARB, November 2016.
---------------------------------------------------------------------------

    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.\44\ These future emissions projections are 
necessary components of the attainment demonstration required under CAA 
section 189(b)(1) and the demonstration of RFP required under section 
172(c)(2).\45\ Emissions projections for future years (which are 
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 it calculated the emissions 
projections. Where a state chooses to allow new major stationary 
sources or major modifications to use emission reductions 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.\46\
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    \44\ 40 CFR 51.1008 and 51.1012. Also, see Emissions Inventory 
Guidance, section 3 (``SIP Inventory Requirements and 
Recommendations'').
    \45\ 40 CFR 51.1004, 51.1008, 51.1011, and 51.1012.
    \46\ 40 CFR 51.165(a)(3)(ii)(C)(1).
---------------------------------------------------------------------------

Summary of State's Submission
    The State included summaries of the planning emissions inventories 
for direct PM2.5 and all PM2.5 precursors 
(NOX, SOX,\47\ VOC,\48\ and ammonia) and the 
documentation for the inventories for the SJV 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'') contains inventory documentation specific to the air 
quality modeling inventories. These portions of the 2018 
PM2.5 Plan contain annual average daily emission inventories 
for 2013 through 2028 projected from the 2012 actual emissions 
inventory,\49\ including the 2013 base year, the 2019 and 2022 RFP 
milestone years, the 2025 Serious area attainment year, and a 2028 
post-attainment RFP year. The State used both the annual average and 
the winter average daily inventories to evaluate emission sources for 
the 2012 annual PM2.5 NAAQS in the 2018 PM2.5 
Plan.\50\
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    \47\ 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 
notice.
    \48\ 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 notice.
    \49\ 2018 PM2.5 Plan, App. B, B-18.
    \50\ Id. at App. B, B-19. The base year inventory is from 
CEIDARS and future year inventories were estimated using CEPAM, 
version 1.05.
---------------------------------------------------------------------------

    The State selected 2013 for the base year emission inventory, 
building on the 2012 actual emissions inventory and considering 
available air quality data, trends, and field studies.\51\ 
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) \52\ of the South Coast Air Quality Management District 
(SCAQMD) and to maintain consistency across various California air 
quality plans.\53\ The State then projected the

[[Page 74315]]

2013 base year emissions inventory (also referred to as the planning 
emissions inventory), presented in Appendix B of the Plan, from that 
2012 actual emission inventory. Regarding the modeling emissions 
inventory, developed from the base year emissions inventory, the State 
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.\54\
---------------------------------------------------------------------------

    \51\ Id. at App. L, 11-12.
    \52\ 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.
    \53\ 2018 PM2.5 Plan, App. B, B-18.
    \54\ Id. at App. L, 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 
SJV, underscoring its use as a conservative base year for modeling 
attainment of the 2012 annual PM2.5 NAAQS. 2018 
PM2.5 Plan, Ch. 7, 7-6.
---------------------------------------------------------------------------

    In addition, simultaneously with submission of the 2018 
PM2.5 Plan, the State submitted the Moderate area plan for 
the SJV for the 2012 annual PM2.5 NAAQS, adopted by the 
District in 2016, that similarly used 2013 for the base year emissions 
inventory (``2016 PM2.5 Plan''). In that plan, the State 
included a modeling demonstration that it would be impracticable for 
the SJV to attain the 2012 annual PM2.5 NAAQS by the 
outermost Moderate area attainment date of December 31, 2021.\55\ The 
modeling demonstration used three overlapping design value periods 
covering 2010-2014 and the 2013 base year emissions inventory to model 
the ambient air quality in 2021.
---------------------------------------------------------------------------

    \55\ 2016 PM2.5 Plan, Ch. 2, section 2.3 (``Summary 
of Modeling Results'') and App. A (``Air Quality Modeling''). The 
EPA has summarized the State's impracticability demonstration in 
greater detail in our proposed rule on the 2016 PM2.5 
Plan. 86 FR 49100, 49113 (September 1, 2021).
---------------------------------------------------------------------------

    The State developed base year inventories in the 2018 
PM2.5 Plan for stationary sources using actual emissions 
reports made by facility operators. The State developed the base year 
emissions inventories for area sources using the most recent models and 
methodologies available at the time the State was developing the 2018 
PM2.5 Plan.\56\ The 2018 PM2.5 Plan 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.\57\ It provides filterable and condensable emissions 
estimates, expressed as annual PM2.5 emissions (tons per 
year), for all of the identified source categories for the years 
relevant for the 2012 annual PM2.5 NAAQS Serious area plan 
requirements, including the 2013 base year, the 2019 and 2022 RFP 
years, the 2025 Serious area attainment year, and a 2028 post-
attainment RFP year.
---------------------------------------------------------------------------

    \56\ 2018 PM2.5 Plan, App. B, section B.2 
(``Emissions Inventory Summary and Methodology'').
    \57\ Id. at App. B, B-42 to B-44.
---------------------------------------------------------------------------

    CARB used EMFAC2014, which was the EPA-approved model at the time 
CARB developed and submitted the inventories, to estimate on-road motor 
vehicle emissions based on transportation activity data from the 2014 
Regional Transportation Plans adopted by the transportation planning 
agencies in the SJV.\58\ Re-entrained paved road dust emissions were 
calculated using a CARB methodology consistent with the EPA's AP-42 
road dust methodology.\59\ 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.\60\
---------------------------------------------------------------------------

    \58\ Id. at App. B, B-37. We note that the vehicle miles 
traveled data used in the 2018 PM2.5 Plan's emissions 
inventory is from the final 2017 Federal Transportation Improvement 
Program from each of the SJV's eight metropolitan planning 
organizations.
    \59\ Id. at App. B, B-28.
    \60\ Id. at App. B, 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.\61\ 
In the 2018 PM2.5 Plan, the District provides for use of 
pre-base year ERCs as offsets by accounting for such ERCs in the 
projected emissions inventory for the 2025 attainment year.\62\ The 
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,\63\ 
NOX, SOX, and VOC emissions by facility.\64\
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    \61\ Id. at App. B, B-19.
    \62\ Id. at App. I, I-1 through I-5.
    \63\ Particulate matter with a diameter of 10 microns or less.
    \64\ 2018 PM2.5 Plan, App. I, tables I-1 through I-5.
---------------------------------------------------------------------------

    Table 1 provides a summary of the 2018 PM2.5 Plan's 
winter (24-hour) average inventories in tpd of direct PM2.5 
and PM2.5 precursor emissions for the 2013 base year. Table 
2 provides a summary of the 2018 PM2.5 Plan's annual average 
inventories of direct PM2.5 and PM2.5 precursor 
emissions for the 2013 base year. For purposes of this proposal, these 
annual average inventories provide bases primarily for our evaluation 
of the precursor demonstration, control measure analysis, attainment 
demonstration, RFP demonstration, and motor vehicle emissions budgets 
(``budgets'') in the 2018 PM2.5 Plan with respect to the 
Serious area attainment plan requirements for the 2012 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 through B-5.

[[Page 74316]]

 
\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 through B-5.
\a\ Totals reflect disaggregated emissions and may not add exactly as shown here due to rounding.

EPA Evaluation and Proposed Action
    The inventories in the 2018 PM2.5 Plan include the 
latest version of California's mobile source emissions model, 
EMFAC2014, that the EPA had approved at the time the State made the SIP 
submissions, and the EPA's most recent AP-42 methodology for paved road 
dust. The inventories comprehensively address all source categories in 
the SJV PM2.5 nonattainment area and are consistent with the 
EPA's inventory guidance.
    In accordance with 40 CFR 51.1008(b)(1), the EPA has evaluated the 
State's justification for using 2013 for the base year emissions 
inventory as a technically appropriate inventory year for the 2012 
annual PM2.5 NAAQS Serious area plan for the SJV. In 
particular, the State describes the technical bases for the selection 
of 2013 for the modeling emissions inventory, explaining that 2013 was 
conducive to PM2.5 formation in the SJV; the important 
DISCOVER-AQ field study measured two significant pollution episodes in 
the SJV in January to February 2013; and the 2013 design values (across 
monitoring sites) were relatively high in comparison to other recent 
years,\65\ making it a conservative choice for future air quality 
projections for RFP and attainment of the 2012 annual PM2.5 
NAAQS. We agree that these points make 2013 both a conservative year 
for modeling future air quality and one that aligns the comprehensive, 
accurate, and recent emissions inventory at the time the State 
developed and submitted the 2018 PM2.5 Plan with empirical 
data from the DISCOVER-AQ field study.
---------------------------------------------------------------------------

    \65\ EPA design value workbook dated May 24, 2021, 
``pm25_designvalues_2018_2020_final_05_24_21.xlsx,'' worksheets 
``Table3a.''
---------------------------------------------------------------------------

    The EPA's approval of the State's demonstration that it was 
impracticable to attain the 2012 annual PM2.5 NAAQS by 2021 
and reclassification of the SJV to Serious for the 2012 annual 
PM2.5 NAAQS was based foremost on the State's modeled 
demonstration.\66\ While we also considered the 2018-2020 design values 
(across monitoring sites) as part of our evaluation, such ambient air 
quality data was not available in 2017-2018 when CARB and the District 
were developing the 2018 PM2.5 Plan.
---------------------------------------------------------------------------

    \66\ 86 FR 67343, 67345. See also, 86 FR 49100, 49117-49118 
(proposed rule on State's Moderate area plan).
---------------------------------------------------------------------------

    Therefore, the EPA proposes to find the State's justification for 
selecting 2013 for the base year emissions inventory to be technically 
appropriate, consistent with 40 CFR 51.1008(b)(1). Furthermore, the 
2013 base year represents actual annual average emissions of all 
sources within the nonattainment area. Direct PM2.5 and 
PM2.5 precursors are included in the inventories, and 
filterable and condensable direct PM2.5 emissions are 
identified separately.
    With respect to future year baseline projections, we have reviewed 
the growth and control factors estimated by the State and propose to 
find them acceptable and thus conclude that the future baseline 
emissions projections in the 2018 PM2.5 Plan reflect 
appropriate calculation methods and the latest planning assumptions at 
the time the State and District were developing the Plan and its 
emissions inventory. 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 and area 
sources, the related rules must be approved by the EPA into the SIP.
    In our rulemaking on the State's attainment plan for the 2006 24-
hour PM2.5 NAAQS in the SJV, we reviewed the baseline 
measures identified as 2018 PM2.5 Plan baseline controls to 
ensure that the measures that are relied upon in the plan are submitted 
and approved as part of the California SIP.\67\ We reaffirm that the 
stationary and area source baseline measures in the 2018 
PM2.5 Plan are approved into the SIP and support the 
emissions reductions for future years in the SJV, with two exceptions 
discussed in section IV.F.3.a of the proposed rule that would not 
materially affect the attainment demonstration in the Plan. With 
respect to mobile sources, the EPA has acted in recent years to approve 
CARB mobile source regulations into the state-wide portion of the 
California SIP.\68\ We therefore propose to find that the future year 
baseline projections in the 2018 PM2.5 Plan are properly 
supported by SIP-approved stationary, area, and mobile source 
measures.\69\
---------------------------------------------------------------------------

    \67\ EPA Region IX, ``Technical Support Document, General 
Evaluation, San Joaquin Valley PM2.5 Plan for the 2006 
PM2.5 NAAQS,'' February 2020 (``EPA's General Evaluation 
TSD''). Table V-A of EPA's General Evaluation TSD shows District 
rules with post-2013 compliance dates that are reflected in the 
future year baseline inventories of the 2018 PM2.5 Plan, 
along with information on the EPA's approval of these rules.
    \68\ See, e.g., 81 FR 39424 (June 16, 2016), 82 FR 14447 (March 
21, 2017), and 83 FR 23232 (May 18, 2018).
    \69\ The baseline emissions projections in the 2018 
PM2.5 Plan assume implementation of CARB's zero emissions 
vehicle (ZEV) sales mandate and greenhouse gas (GHG) standards, 
based on the EMFAC2014 model that was the current EPA-approved model 
available at the time of the SIP's development and the assumptions 
that were available at that time. On September 27, 2019, the U.S. 
Department of Transportation and the EPA (the Agencies) issued the 
joint action known as the ``Safer Affordable Fuel-Efficient (SAFE) 
Vehicles Rule Part One: One National Program'' (``SAFE I'') that, 
among other things, withdrew the EPA's 2013 waiver of preemption of 
CARB's ZEV sales mandate and vehicle GHG standards. 84 FR 51310 
(September 27, 2019). See also proposed SAFE rule at 83 FR 42986 
(August 24, 2018). On April 30, 2020 (85 FR 24174), the Agencies 
issued a notice of final rulemaking for the ``The Safer Affordable 
Fuel-Efficient (SAFE) Vehicles Rule for Model Years 2021-2026 
Passenger Cars and Light Trucks'' (``SAFE II''), establishing the 
federal fuel economy and GHG vehicle emissions standards based on 
the August 2018 SAFE proposal. The effect of both SAFE final rules 
(SAFE I and SAFE II) on the on-road vehicle mix in the SJV 
nonattainment area and on the resulting vehicular emissions is 
expected to be minimal during the timeframe addressed in this SIP 
revision. Therefore, we anticipate the SAFE final rules would not 
materially change the demonstration of attainment of the 2012 annual 
PM2.5 NAAQS in the SJV by the Serious area attainment 
date of December 31, 2025.

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

[[Page 74317]]

    For these reasons, we are proposing to approve the 2013 base year 
emissions inventory in the 2018 PM2.5 Plan as meeting the 
requirements of CAA section 172(c)(3) and 40 CFR 51.1008. We are also 
proposing to find that the future year baseline inventories in the 2018 
PM2.5 Plan satisfy the requirements of 40 CFR 51.1008(b)(2) 
and 51.1012(a)(2) and provide an adequate basis for the control 
measure, attainment, and RFP demonstrations for the 2012 annual 
PM2.5 NAAQS in the 2018 PM2.5 Plan.

B. PM2.5 Precursors

Requirements for Control of PM2.5 Precursors
    The provisions of subpart 4 of part D, title I of the CAA 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.'' The EPA has identified 
NOX, SO2, VOC, and ammonia as precursors to the 
formation of PM2.5.\70\ 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 sources, except as otherwise provided in the Act 
(e.g., in CAA section 189(e)).
---------------------------------------------------------------------------

    \70\ 81 FR 58010, 58018.
---------------------------------------------------------------------------

    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 reasonably available control measures (RACM), 
reasonably available control technology (RACT), BACM, BACT, most 
stringent measures (MSM), and nonattainment 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. For example, under the EPA's longstanding 
interpretation of the control requirements that apply to stationary and 
mobile sources of PM10 precursors in the nonattainment area 
under CAA section 172(c)(1) and subpart 4,\71\ a state may demonstrate 
in a SIP submission that control of a certain precursor pollutant is 
not necessary in light of its insignificant contribution to ambient 
PM10 levels in the nonattainment area.\72\
---------------------------------------------------------------------------

    \71\ General Preamble, 13539-13542.
    \72\ 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.\73\ 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.\74\
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    \73\ 40 CFR 51.1006(a)(1).
    \74\ Id.
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    In addition, in May 2019, the EPA issued the ``PM2.5 
Precursor Demonstration Guidance'' (``PM2.5 Precursor 
Guidance''), 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.\75\ 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 differences that are distinguishable 
statistically in monitored data. 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 fails 
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. 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. The EPA's recommended annual 
average contribution threshold for the annual PM2.5 NAAQS is 
0.2 [mu]g/m\3\.\76\
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    \75\ ``PM2.5 Precursor Demonstration Guidance,'' EPA-
454/R-19-004, May 2019, including Memo 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 Memo 
dated November 17, 2016, from Stephen D. Page, Director, OAQPS, EPA 
to Regional Air Division Directors, Regions 1-10, EPA.
    \76\ PM2.5 Precursor Guidance, 17.
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    We are evaluating the 2018 PM2.5 Plan with respect to 
the Serious area attainment plan requirements in accordance with the 
presumption embodied within subpart 4 that the State must address all 
PM2.5 precursors in its 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 the 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 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.
Summary of State's Submission
    The State's precursor demonstration and conclusions are found in 
Chapter 7 (``Demonstration of Federal Requirements for 2012 
PM2.5 Standard'') and Appendix G (``Precursor 
Demonstration'') of the 2018 PM2.5 Plan. CARB also provides 
clarifying information on its precursor assessment, including an 
Attachment A to its letter transmitting the 2018 PM2.5 Plan 
to the

[[Page 74318]]

EPA \77\ and further clarifications in five email transmittals.\78\
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    \77\ Letter dated May 9, 2019, from Richard W. Corey, Executive 
Officer, CARB, to Michael Stoker, Regional Administrator, EPA Region 
IX, Attachment A (``Clarifying information for the San Joaquin 
Valley 2018 Plan regarding model sensitivity related to ammonia and 
ammonia controls'').
    \78\ Email dated June 20, 2019, ``RE: SJV model disbenefit from 
SOX reduction,'' from Jeremy Avise, CARB, to Scott 
Bohning, EPA Region IX, with attachment (``CARB's June 2019 
Precursor Clarification''); email dated September 19, 2019, ``FW: 
SJV species responses,'' from Jeremy Avise, CARB, to Scott Bohning, 
EPA Region IX, 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, 
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'').
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    The State estimates that anthropogenic emissions of NOX, 
ammonia, SOX, and VOC will decrease by 64 percent (%), 1%, 
6%, and 9%, respectively, between 2013 and 2025.\79\ The 2018 
PM2.5 Plan provides both concentration-based and 
sensitivity-based analyses of precursor contributions to ambient 
PM2.5 concentrations in the SJV. Based on these analyses, 
the State concludes that emissions of NOX (as well as direct 
PM2.5) contribute significantly to ambient PM2.5 
levels that exceed the PM2.5 NAAQS in the SJV but ammonia, 
SOX, and VOC do not contribute significantly to such 
exceedances.
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    \79\ 2018 PM2.5 Plan, Ch. 7, 7-5 and Table 7-2. We 
also note that a copy of the contents of the 2018 PM2.5 
Plan, App. G appears in the CARB Staff Report, App. C4 (``Precursor 
Demonstrations for Ammonia, SOX, and ROG'').
---------------------------------------------------------------------------

    We summarize the State's analyses and conclusions for ammonia, 
SOX, and VOC in the following paragraphs. For a more 
detailed summary of the precursor demonstration in the Plan, please 
refer to two EPA technical support documents (TSDs): The first covers 
all the precursors and the second one specifically addresses ammonia. 
The first TSD is 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 PM2.5 Precursor TSD''), which provides the 
EPA's summary of the State's precursor analyses for all four 
PM2.5 precursors. Most of our analysis in the EPA's 
PM2.5 Precursor TSD is applicable to the portion of the Plan 
pertaining to the Serious area plan for the 2012 annual 
PM2.5 NAAQS. For example, the State's precursor 
demonstration used 2015 annual average concentration data for its 
concentration-based analysis, examined both 24-hour and 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 both 24-hour average and annual average ambient 
PM2.5 concentrations to emission reductions of each 
PM2.5 precursor. Our evaluation of such factors, as 
described in the EPA's PM2.5 Precursor TSD, is similarly 
applicable for the 2012 annual PM2.5 NAAQS.
    With respect to ammonia emission reductions, the EPA's 
PM2.5 Precursor TSD summarizes the State's analysis of 24-
hour average sensitivity of ambient PM2.5 concentrations 
across monitoring sites and years (see Table 2 of the EPA's 
PM2.5 Precursor TSD). The EPA's second TSD, ``Technical 
Support Document, EPA Evaluation of Ammonia Precursor Demonstration, 
San Joaquin Valley Moderate Area PM2.5 Plan for the 2012 
PM2.5 NAAQS,'' August 2021 (``EPA's Ammonia Precursor 
TSD''), summarizes the annual average sensitivity of ambient 
PM2.5 concentrations to ammonia emission reductions (see 
Table 2 of the EPA's Ammonia Precursor TSD) and provides further 
summary and context with respect to the State's ammonia precursor 
demonstration for the 2012 annual PM2.5 NAAQS.
    For ammonia, SOX, and VOC, CARB assesses the 2015 annual 
average concentration of each precursor in ambient PM2.5 at 
Bakersfield, for which the necessary speciated PM2.5 data 
was available and where the highest PM2.5 design values have 
been recorded in most years, and compares those concentrations to the 
recommended annual average contribution threshold of 0.2 [mu]g/
m\3\.\80\ CARB concludes that the 2015 annual average contributions of 
ammonia, SOX, and VOC are 5.2 [mu]g/m\3\, 1.6 [mu]g/m\3\ and 
6.2 [mu]g/m\3\, respectively.
---------------------------------------------------------------------------

    \80\ 2018 PM2.5 Plan, App. G, 3. The 2018 
PM2.5 Plan presents a graphical representation of annual 
average ambient PM2.5 components (i.e., crustal 
particulate matter, elemental carbon, organic matter, ammonium 
sulfate, and ammonium nitrate) for 2011-2013 for Bakersfield, 
Fresno, and Modesto. 2018 PM2.5 Plan, Ch. 3, 3-3 to 3-4.
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    For ammonia, SOX, and VOC, the State modeled the 
sensitivity of ambient PM2.5 to 30% and 70% 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 
PM2.5 NAAQS; and 2024 is the modeled attainment year for the 
2006 24-hour PM2.5 NAAQS. For the 2012 annual 
PM2.5 NAAQS, the modeled attainment year is 2025, but the 
State did not conduct precursor sensitivity modeling for that 
additional year. Instead the State assumed that 2024 and 2025 would 
have very similar results; \81\ and results for 2024 were used as a 
proxy for those of 2025. Emissions totals for those two years are 
within 0.2% of each other for all pollutants, except that 
NOX emissions are 3% lower in 2025.\82\ Depending on the 
analysis year and percentage precursor emission reduction, the 
sensitivity of ambient PM2.5 to reductions in annual average 
precursor emissions ranges from 0.08 [mu]g/m\3\ to 2.30 [mu]g/m\3\ for 
ammonia; from -0.05 [mu]g/m\3\ to 0.15 [mu]g/m\3\ for SOX; 
and from -0.50 [mu]g/m\3\ to 0.40 [mu]g/m\3\ for VOC.\83\
---------------------------------------------------------------------------

    \81\ Id. at Ch. 7, 7-7, and App. G, 10.
    \82\ 2018 PM2.5 Plan, App. B. As discussed below, the 
lower NOX emissions in 2025 compared to 2024 mean that 
the PM2.5 response to ammonia reductions would be lower 
than those stated in the Plan's precursor demonstration; using 2024 
results is more conservative than using 2025 results.
    \83\ Id. at App. G, tables 2 through 7 for ammonia, tables 8 and 
9 for SOX, and tables 10 through 15 for VOC.
---------------------------------------------------------------------------

    For ammonia, the modeled sensitivity of ambient PM2.5 
levels to a 30% or 70% emission reduction exceeds 0.2 [mu]g/m\3\ in 
certain years at specific monitoring sites. As discussed in section 
IV.B.3.a of this proposed rule, for the 30% reduction results for 2024, 
upon which the State primarily relied, 2 out of 15 monitoring sites 
have responses above the threshold and the ambient PM2.5 
response declines substantially from 2020 to 2024, with the decline 
being generally larger for the sites with the highest projected 
PM2.5 levels. In contrast, for SOX and VOC, the 
modeled sensitivity of ambient PM2.5 levels to a 30% or 70% 
emission reduction in either precursor is below 0.2 [mu]g/m\3\ in all 
model scenarios except one, including a disbenefit (i.e., ambient 
PM2.5 levels increase when precursor emissions are reduced) 
at some monitoring sites for both precursors. For 2013, the State's 
modeling shows an ambient PM2.5 change greater than 0.2 
[mu]g/m\3\ at 7 out of 15 monitoring sites in response to a 70% VOC 
emission reduction. According to the State, however, such sensitivity 
results do not reflect the current atmospheric chemistry in the SJV 
given the projected emission reductions from 2013 to 2024 for all four 
PM2.5 precursors, especially for VOC and NOX, as 
further described in this proposed rule.

[[Page 74319]]

    The State supplemented the sensitivity analysis, particularly for 
ammonia, with consideration of additional information such as emission 
trends, the appropriateness of future year versus base year 
sensitivity, available emission controls, and the severity of 
nonattainment.\84\ 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.\85\
---------------------------------------------------------------------------

    \84\ Id. at App. G, 5.
    \85\ PM2.5 Precursor Guidance, 18-19 (consideration 
of additional information), 31 (available emission controls), and 
35-36 (appropriateness of future year versus base year sensitivity).
---------------------------------------------------------------------------

    The State notes that a 53% reduction in (baseline) NOX 
emissions is projected to occur between 2013 and 2024,\86\ so the 
conditions in the early years will not persist and the future year is 
more representative of the Valley's ambient conditions than earlier 
years. The 2018 PM2.5 Plan's precursor demonstration also 
presents a review of District agricultural rules that control VOC 
emissions and also provide ammonia co-benefits. The State concludes 
that a 30% reduction is a reasonable upper bound on the ammonia 
reductions to model. Finally, the 2018 PM2.5 Plan's 
precursor demonstration presents extensive support for the State's 
conclusion regarding an ambient excess of ammonia relative to 
NOX, i.e., that particulate ammonium nitrate formation is 
NOX-limited, and will become increasingly NOX-
limited as NOX reductions increase into the future.
---------------------------------------------------------------------------

    \86\ 2018 PM2.5 Plan, App. G, 8.
---------------------------------------------------------------------------

EPA Evaluation and Proposed Action
    The EPA has evaluated the State's precursor demonstration in the 
2018 PM2.5 Plan, as well as other relevant information 
available to the EPA, consistent with the PM2.5 SIP 
Requirements Rule and the recommendations in the PM2.5 
Precursor Guidance. Based on this evaluation, the EPA agrees with the 
State's conclusion that NOX emissions contribute 
significantly to ambient PM2.5 levels that exceed the 2012 
annual PM2.5 NAAQS in the SJV and that NOX 
emission sources, therefore, remain subject to control requirements 
under subparts 1 and 4 of part D, title I of the Act. Additionally, for 
the reasons provided in the following paragraphs, the EPA proposes to 
approve the State's comprehensive precursor 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 2012 annual PM2.5 
NAAQS in the SJV.
    The State based its analyses on the latest available data and 
studies concerning ambient PM2.5 formation in the SJV from 
precursor emissions. For the required concentration-based analysis, the 
State assessed the absolute annual average contribution of each 
precursor to ambient PM2.5 (i.e., in 2015). Given that the 
absolute concentrations in 2015 were above the EPA's recommended 
contribution thresholds for both the 24-hour and annual average 
PM2.5 NAAQS, the State proceeded to a sensitivity-based 
analysis, consistent with 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, and compared the result to the EPA's recommended contribution 
threshold. In particular, the State considered the EPA's recommended 
range of emission reductions (30% to 70%) for the 2013 base year, 2020 
(an interim year), and the 2024 future year, and quantified the 
estimated response of ambient PM2.5 concentrations to 
precursor emission changes in the SJV.
    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 both 2021 and 2025. These decreases are 
included in the State's modeled projections of ambient PM2.5 
levels in the SJV 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.\87\
---------------------------------------------------------------------------

    \87\ PM2.5 Precursor Guidance, 35.
---------------------------------------------------------------------------

    In the subsections that follow, we summarize our evaluation of the 
State's precursor demonstrations for ammonia, SOX, and VOC 
for purposes of the 2012 annual PM2.5 NAAQS in the SJV.
(a) Ammonia Precursor Demonstration
    In the 2018 PM2.5 Plan, CARB estimates the ambient 
PM2.5 response to both a 30% and a 70% emissions reduction 
in 2013, 2020, and 2024. We have evaluated CARB's sensitivity-based 
contribution analyses for 2013, 2020, and 2024 (in the 2018 
PM2.5 Plan) and CARB's determination that 2024 results are 
representative of conditions in the SJV for purposes of a sensitivity-
based analysis, as discussed in the following paragraphs. The EPA's 
PM2.5 Precursor Guidance explicitly provides for 
consideration of a future year, such as the attainment year.\88\ We 
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% 
modeled ammonia emissions reduction in its precursor demonstration for 
ammonia. The State primarily relied on the 30% reduction results after 
concluding that 30% was a reasonable upper bound on potential ammonia 
reductions, based on past research on ammonia emissions and potential 
control options for agricultural sources. The EPA agrees that this is a 
reasonable upper bound on ammonia emissions reductions to use in the 
precursor demonstration, as discussed in EPA's approval of the 
precursor demonstration for the 2006 24-hour PM2.5 
NAAQS.\89\ We provide a detailed evaluation of the State's precursor 
demonstration for ammonia emissions in the EPA's Ammonia Precursor TSD.
---------------------------------------------------------------------------

    \88\ Id.
    \89\ 85 FR 17382 (March 27, 2020), 17395; EPA's PM2.5 
Precursor TSD, 13.
---------------------------------------------------------------------------

    The precursor demonstration in the 2018 PM2.5 Plan 
indicates that the ambient response to a 30% ammonia emission reduction 
would exceed the EPA's recommended contribution threshold of 0.2 [mu]g/
m\3\ for 14 out of 15 monitoring sites in the 2013 analysis year, and 
at 9 out of 15 for the 2020 analysis year. For the 2024 analysis year, 
2 of the 15 sites would exceed the contribution threshold, Madera and 
Hanford. In absolute terms, the ambient PM2.5 response 
declines from 0.24 [mu]g/m\3\ in 2020 to 0.12 [mu]g/m\3\ in 2024 at 
Bakersfield-Planz, the highest concentration site. The Madera and 
Hanford responses decline, respectively, from 0.36 to 0.21 [mu]g/m\3\, 
and from 0.42 to 0.26 [mu]g/m\3\. The average response over all 
monitoring sites declines from 0.23 [mu]g/m\3\ to 0.14 [mu]g/m\3\, with 
the decline being generally larger for the sites with the highest 
projected PM2.5 levels.
    While the Madera and Hanford responses to ammonia reductions are 
above the contribution threshold, additional information about these 
locations leads the EPA to give these responses lower weight in the 
overall assessment of whether ammonia contributes significantly to 
PM2.5 levels. The State notes that the 2013 base year Madera 
monitored concentrations are

[[Page 74320]]

biased high,\90\ which would lead to model estimates of the response to 
ammonia reductions that are biased high (because for model projections, 
relative responses of the model to emissions changes are applied to 
monitored concentrations). While the State did not discuss the evidence 
for this in detail in its 2018 PM2.5 Plan, it is consistent 
with an analysis of Madera measured concentrations that the State 
provided in a prior PM2.5 plan for the SJV.\91\ The EPA has 
previously discussed that the Madera data for the limited period of 
2011 to 2013 are not representative for purposes of an attainment 
demonstration.\92\
---------------------------------------------------------------------------

    \90\ 2018 PM2.5 Plan, App. G, 14.
    \91\ ``Assessment of the Representativeness of 2011 
PM2.5 Beta Attenuation Monitor Data from Madera,'' in 
``Staff Report, ARB Review of San Joaquin Valley PM2.5 
State Implementation Plan,'' adopted by CARB on May 21, 2015, App. 
A, ``Weight of Evidence Analysis.''
    \92\ 81 FR 6936, 6971 (February 9, 2016). The conclusion that 
2011-2013 Madera data was biased high was based on it not fitting 
the north-south concentration gradient historically seen in 
relations to other monitors, a comparison to data from a second 
monitor at the same site, and the return to the historic pattern 
after adjustments were made to instrument operation after checking 
its zero point. The data is considered valid in the EPA's Air 
Quality System (AQS) for purposes of assessing whether the NAAQS is 
met. However, the EPA considered it to be anomalously high for that 
period, and not representative for use in modeling. Adjusted 
substituted data from nearby monitors had concentrations about 10% 
lower, and were accepted by the EPA for the demonstration of 
attainment of the 1997 annual PM2.5 NAAQS.
---------------------------------------------------------------------------

    For the 2018 PM2.5 Plan precursor demonstration, 
Madera's ambient PM2.5 response in 2024 to a 30% ammonia 
emissions reduction was 0.21 [mu]g/m\3\, just 5% above EPA's 
recommended contribution threshold of 0.2 [mu]g/m\3\. Because the 2024 
modeling starting point was a base design value using monitored 
concentrations from 2010-2014, if more typical Madera concentrations 
were used, it is likely that the 2024 Madera response to ammonia 
reductions would be below the contribution threshold. Moreover, given 
the NOX emission reductions that are projected to continue 
from 2024 to 2025, the EPA expects that PM2.5 sensitivity to 
ammonia reductions would decrease from the 0.21 [mu]g/m\3\ unadjusted 
value in 2024 to a lower value in 2025, likely decreasing even the 
unadjusted, biased-high value to below the threshold.
    There is also information suggesting that the Hanford response to 
ammonia reductions may be lower than indicated in the State's 2018 
PM2.5 Plan precursor demonstration. An independent study 
using aircraft and surface data from the winter 2013 DISCOVER-AQ \93\ 
campaign, a key period in the 2018 PM2.5 Plan's 2013 base 
year, found that the Community Multiscale Air Quality (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).\94\ If the model's ammonia concentrations were 
higher to better match observations, then there would be relatively 
more ammonia per NOX; ammonia then would be less of a 
limiting factor for particulate ammonium nitrate formation and the 
model response to ammonia reductions would be lower. This phenomenon is 
described more fully below.
---------------------------------------------------------------------------

    \93\ 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.
    \94\ 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, 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.
---------------------------------------------------------------------------

    The 2018 PM2.5 Plan did not include an evaluation of 
model performance for ammonia per se (just for particulate ammonium), 
but in supplemental transmittals \95\ CARB described the results of two 
analyses confirming the likely underestimation of ammonia. CARB 
compared CMAQ model predictions of ammonia with the 2013 DISCOVER-AQ 
aircraft measurements and found that ammonia was underpredicted, and 
noted that this would result in the PM2.5 response to 
ammonia reductions being overpredicted. CARB also compared 2017 
satellite measurements of ammonia with CMAQ model predictions and found 
that modeled ammonia concentrations were half of the magnitude of the 
satellite observations at some locations, and the modeled average in 
the SJV was about 25% less than observed. CARB concluded that the model 
tends to overpredict the sensitivity of ammonium nitrate formation to 
ammonia emission reductions. CARB also speculated that the 
underprediction could be partly be explained by the underestimation of 
ammonia emissions using current methodologies.\96\ If modeled ammonia 
concentrations were closer to observations, e.g., via increased 
emissions in the model, then the modeled response to ammonia precursor 
reductions would be lower than shown in the 2018 PM2.5 
Plan's precursor demonstration. An increase in modeled ambient ammonia 
(such as via a larger emissions estimate) would also make the model 
response more consistent with the evidence from the ambient measurement 
studies that are discussed next.
---------------------------------------------------------------------------

    \95\ CARB's April 19, 2021, Precursor Clarification and CARB's 
April 26, 2021, Precursor Clarification.
    \96\ As discussed in EPA's Ammonia Precursor TSD, there is 
evidence that ammonia emisions are underestimated, based on 
comparsons between satellite measurements and what would be expected 
from emissions inventories.
---------------------------------------------------------------------------

    As additional information for assessing the contribution of ammonia 
to PM2.5, the State discussed evidence from multiple ambient 
measurement studies.\97\ 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. 
These ambient studies provide strong evidence independent of the 
modeling that PM2.5 would respond only weakly to ammonia 
emissions reductions.
---------------------------------------------------------------------------

    \97\ 2018 PM2.5 Plan, 6-7, and App. G, G-9 to G-10; 
the CARB 2018 Staff Report, App. C, 12-15; and Submittal Letter, 
Attachment A. These studies are also discussed in the EPA's 
PM2.5 Precursor TSD.
---------------------------------------------------------------------------

    Another consideration is that the PM2.5 benefit of 
ammonia emission reductions is projected to decline steeply over time. 
In selecting the analysis year for a precursor demonstration, we 
believe it is appropriate to consider changes in 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.\98\ The ``anticipated growth or loss of sources . . . or trends 
in ambient speciation data and precursor emissions'' \99\ are among the 
``facts and circumstances of the area'' \100\ 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

[[Page 74321]]

represent the period that ammonia sources will operate in, because of 
the steep decline in NOX emissions projected to occur by 
2024 and 2025. We consider it reasonable for the State to focus on the 
ambient PM2.5 response to ammonia emission reductions in 
2024, rather than an earlier year, as the modeled response in 2024 in 
the SJV better reflects the potential benefit of ammonia control 
measures for purposes of expeditious attainment of the 2012 annual 
PM2.5 NAAQS.
---------------------------------------------------------------------------

    \98\ PM2.5 Precursor Guidance, 35.
    \99\ Id. at 18.
    \100\ PM2.5 SIP Requirements Rule, 40 CFR 
51.1006(a)(1)(ii).
---------------------------------------------------------------------------

    The State's precursor demonstration in the 2018 PM2.5 
Plan shows that ambient sensitivity to ammonia emission reductions in 
the SJV declines steeply over time. Between 2020 and 2024, the modeled 
response to a 30% ammonia emission reduction declines by 50% at the 
Bakersfield-Planz monitoring site, which has the highest projected 
PM2.5 level, and by 37% averaged over all monitoring 
sites.\101\ As noted above, in absolute terms, the ambient 
PM2.5 response declines from 0.24 [mu]g/m\3\ in 2020 to 0.12 
[mu]g/m\3\ in 2024 at Bakersfield-Planz, which has the highest 
projected PM2.5 design value, and from 0.23 [mu]g/m\3\ to 
0.14 [mu]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 0.2 [mu]g/m\3\ threshold 
declines from 9 out of 15 down to 1 or 2 out of 15.\102\ As discussed 
above, ammonia sensitivity declines because of the shifting atmospheric 
chemistry caused by NOX emissions decreases. NOX 
emissions are projected to decrease 27% between 2020 and 2024 due to 
baseline measures (e.g., existing motor vehicle controls). 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 or current conditions. Between 
2024 and 2025, the attainment year, NOX emissions are 
projected to decrease by an additional 3.5% from 2024 levels,\103\ so 
that the response to ammonia reductions in the attainment year would be 
lower than the 2024 results reported in the Plan.
---------------------------------------------------------------------------

    \101\ Extrapolating the 2018 PM2.5 Plan results to 
2025, the percent declines are 55% and 40%, respectively, which are 
larger still than those for 2024.
    \102\ 2018 PM2.5 Plan, App. G, tables 4 and 5, G-11. 
As discussed above, the response for the Madera site is likely below 
the contribution threshold since its monitored concentrations are 
biased high.
    \103\ Annual average NOX emissions are projected to 
decrease from 148.9 tpd in 2024 to 143.7 tpd in 2025. 2018 
PM2.5 Plan, App. B, Table B-2.
---------------------------------------------------------------------------

    Finally, based on the 2024 sensitivity results,\104\ if ammonia 
emissions were reduced by 30%, the area's projected 12.0 [mu]g/m\3\ 
design value, occurring at the Bakersfield-Planz monitoring site, would 
be reduced by 0.12 [mu]g/m\3\, which would not be considered 
significant (it is below the EPA's recommended threshold of 0.2 [mu]g/
m\3\).
---------------------------------------------------------------------------

    \104\ 2018 PM2.5 Plan, App. G, tables 5 and 7, 11-12. 
The response to 2025 ammonia reductions would be lower than the 
values stated in the text, due to the effect of declining 
NOX emissions.
---------------------------------------------------------------------------

    In sum, we conclude that the State quantified the sensitivity of 
ambient PM2.5 levels to reductions in ammonia emissions 
using appropriate modeling technique; the modeled response to ammonia 
reductions is likely lower than reported; and the State's choice of 
2024 and 2025 as the reference points for purposes of evaluating the 
sensitivity of ambient PM2.5 levels to ammonia emission 
reductions is well-supported. Based on all of 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 2012 annual PM2.5 NAAQS in the SJV.
(b) SOX Precursor Demonstration
    In the 2018 PM2.5 Plan, CARB estimated the 2013 ambient 
PM2.5 response to a 30% SOX emission reduction to 
range from -0.01 [mu]g/m\3\ to 0.07 [mu]g/m\3\ and estimated the 
ambient PM2.5 response to a 70% SOX emission 
reduction to range from -0.05 [mu]g/m\3\ to 0.15 [mu]g/m\3\.\105\ The 
State also provides an emissions trend chart that shows SOX 
emissions to be steady at approximately 8 tpd from 2013 through 2024. 
Given that the relative levels of estimated SOX and ammonia 
emissions over that timeframe remain similar, the State concludes that 
the 2013 sensitivities are also representative of future years.\106\ 
The State also provides the ambient PM2.5 responses in 2013, 
2020, and 2024 to 30% and 70% reductions in SOX emissions, 
all of which are below the 0.2 [mu]g/m\3\ contribution threshold.\107\
---------------------------------------------------------------------------

    \105\ Id. at App. G, 15-16, tables 8 and 9.
    \106\ 2018 PM2.5 Plan, App. G, 15. The State includes 
modeling of 30% and 70% reductions of SOX only for 2013, 
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. App. G, 17. CARB's 
September 2019 Precursor Clarification provides the 2020 and 2024 
sensitivity results, which are indeed very close to those for 2013.
    \107\ CARB's September 2019 Precursor Clarification.
---------------------------------------------------------------------------

    We note that the 2018 PM2.5 Plan's sensitivity estimates 
for 2013 are well below that threshold for both the 30% and 70% 
emission reduction scenarios and even negative for certain monitoring 
sites. Given those results and the steady SOX emission 
levels over 2013 to 2025 (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, on the basis of these modeled ambient PM2.5 
responses to SOX emission reductions in the SJV, and 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 2012 
annual PM2.5 NAAQS in the SJV.
(c) VOC Precursor Demonstration
    In the 2018 PM2.5 Plan, the State found that the ambient 
PM2.5 response to VOC emission reductions were generally 
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 11 out of 15 sites in 2024. Only for a 
70% emission 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.\108\
---------------------------------------------------------------------------

    \108\ 2018 PM2.5 Plan, App. G, 18-19, tables 10 and 
11.
---------------------------------------------------------------------------

    We note that the 2018 PM2.5 Plan's sensitivity estimates 
for 2020 and 2024 are well below that threshold for both the 30% and 
70% emission reduction scenarios, and even negative for certain 
monitoring sites. The State also provides an emissions trend chart that 
shows VOC emissions are projected to decrease by about 30 tpd, or 9% 
between 2013 and 2020 as well as between 2013 and 2024, and concludes 
that 2013 sensitivity results are not representative into the future 
and that the 2020 and 2024 results are representative.\109\ Finally, 
the State concludes that VOC emissions do not contribute significantly 
to PM2.5 levels that exceed the 2012 annual PM2.5 
NAAQS.
---------------------------------------------------------------------------

    \109\ Id. at App. G, 19-20.
---------------------------------------------------------------------------

    The EPA has evaluated and agrees with the State's determination in 
the 2018 PM2.5 Plan that the projected 2024 year is more 
representative of conditions in the SJV for sensitivity-based analyses 
and that VOC reductions in 2024 would mostly result in a

[[Page 74322]]

disbenefit to ambient PM2.5 levels, seen at 11 of 15 
monitoring sites. The EPA agrees that the 9% VOC emissions decrease 
from 2013 to 2024 supports reliance on the 2024 modeling results. 
Furthermore, there is projected to be a large decrease in 
NOX emissions over this period, as described 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% VOC emission 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 2024 modeled responses to VOC reductions. The EPA also 
concludes that the State provided a reasonable explanation for the VOC 
reduction disbenefit and evidence that it occurs in the SJV; as 
discussed in the EPA's PM2.5 Precursor TSD, VOC reductions 
led to less peroxyacetyl nitrate formation, and so to greater 
availability of nitrate to form particulate ammonium nitrate.\110\
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    \110\ EPA's PM2.5 Precursor TSD, 22.
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    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 2012 annual PM2.5 
NAAQS in the SJV.

C. Air Quality Modeling

1. Requirements for Air Quality Modeling
    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 noted in sections I and II of this 
proposed rule, the outermost statutory Serious area attainment date for 
the 2012 annual PM2.5 NAAQS in the SJV is December 31, 2025.
    The PM2.5 SIP Requirements Rule explains that Serious 
area plans under CAA section 189(b) must include a demonstration 
(including air quality modeling) that the control strategy provides for 
attainment of the PM2.5 NAAQS as expeditiously as 
practicable.\111\ 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), and any other emissions controls that are needed for 
expeditious attainment of the NAAQS.
---------------------------------------------------------------------------

    \111\ 40 CFR 51.1011(b)(1); 81 FR 58010, 58087.
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    The EPA's PM2.5 modeling guidance \112\ (``Modeling 
Guidance'' and ``Modeling Guidance Update'') recommends that states use 
a photochemical model, such as the CMAQ model, 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.\113\ The Modeling Guidance recommends that the modeled response 
to the emission changes between the base and future years be used to 
calculate relative response factors (RRFs). The modeled RRFs are then 
applied to the monitored design value in the base year 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. Because each species 
is handled separately, before applying an RRF, the base year 
PM2.5 design value must first be split into its species 
components, using available chemical species measurements. The Modeling 
Guidance provides additional detail on the recommended approach.\114\
---------------------------------------------------------------------------

    \112\ Memorandum dated November 29, 2018, from Richard Wayland, 
Air Quality Assessment Division, OAQPS, EPA, to Regional Air 
Division Directors, EPA, Subject: ``Modeling Guidance for 
Demonstrating Air Quality Goals for Ozone, PM2.5, and 
Regional Haze,'' (``Modeling Guidance''), and Memorandum dated June 
28, 2011, from Tyler Fox, Air Quality Modeling Group, OAQPS, EPA, to 
Regional Air Program Managers, EPA, Subject: ``Update to the 24 Hour 
PM2.5 NAAQS Modeled Attainment Test,'' (``Modeling 
Guidance Update'').
    \113\ 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. The ``base case'' modeling 
simulates measured concentrations for a given time period, using 
emissions and meteorology for that same year. The modeling ``base 
year'' (which can be the same as the base case year) is the 
emissions starting point for the plan and for projections to the 
future year, both of which are modeled for the attainment 
demonstration. Modeling Guidance, 37-38. Note that CARB sometimes 
uses ``base year'' synonymously with ``base case'' and ``reference 
year'' instead of ``base year.''
    \114\ Modeling Guidance, section 4.4, ``What is the Modeled 
Attainment Tests for the Annual Average PM2.5 NAAQS.''
---------------------------------------------------------------------------

2. Summary of State's Submission
    The 2018 PM2.5 Plan includes a modeled demonstration 
projecting that the SJV will attain the 2012 annual PM2.5 
NAAQS by December 31, 2025. The Plan's primary discussion of the 
photochemical modeling appears in Appendix K (``Modeling Attainment 
Demonstration'') of the 2018 PM2.5 Plan. The State briefly 
summarizes the area's air quality problem in Chapter 2.2 (``Air Quality 
Challenges and Trends'') and summarizes the modeling results in Chapter 
7.4 (``Attainment Demonstration and Modeling'') of the 2018 
PM2.5 Plan. The State provides a conceptual model of 
PM2.5 formation in the SJV as part of the modeling protocol 
in Appendix L (``Modeling Protocol''). Appendix J (``Modeling Emission 
Inventory'') describes emission input preparation procedures. The State 
presents additional relevant information in Appendix C (``Weight of 
Evidence Analysis'') of the CARB 2018 Staff Report, which includes 
ambient trends and other data in support of the demonstration of 
attainment by 2025.
3. EPA Evaluation and Conclusion
    CARB's air quality modeling approach investigated the many 
interconnected facets of modeling ambient PM2.5 in the SJV, 
including model input preparation, model performance evaluation, use of 
the model output for the numerical NAAQS attainment test, and modeling 
documentation. Specifically, this required the development and 
evaluation of a conceptual model, modeling protocol, episode (i.e., 
base year) selection, modeling domain, CMAQ model selection, initial 
and boundary condition procedures, meteorological model choice and 
performance, modeling emissions inventory preparation procedures, model 
performance, attainment test procedure, and adjustments to baseline air 
quality for modeling. These analyses are generally consistent with the 
EPA's recommendations in the Modeling Guidance.
    The model performance evaluation in section 5.2 (``CMAQ Model 
Evaluation'') of Appendix K of the 2018 PM2.5 Plan included 
statistical and graphical measures of model performance.
    The EPA's evaluation of the modeling for the 2012 annual 
PM2.5 NAAQS incorporates the evaluation that the EPA 
previously did for other NAAQS in the

[[Page 74323]]

2018 PM2.5 Plan. The EPA previously evaluated and approved 
the modeling conducted for the 2006 24-hour PM2.5 NAAQS as 
part of the 2018 PM2.5 Plan; see 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 2006 NAAQS Modeling TSD'') accompanying that 
action for details.\115\ The conclusions in the EPA's 2006 NAAQS 
Modeling TSD focused on the 2006 24-hour PM2.5 NAAQS; in 
this notice we extend the evaluation with information specific to the 
2012 annual PM2.5 NAAQS.
---------------------------------------------------------------------------

    \115\ The model performance is discussed further in section J 
(``Air Quality Model Performance'') of the EPA's 2006 NAAQS 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. 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 concentrations; this is done for each monitor, 
PM2.5 species, and calendar quarter. But for the 24-hour 
averaging time, the recommended procedure uses the highest individual 
concentration days in each quarter, whereas for the annual average, it 
uses the average of all days in each quarter. For the current action on 
the 2018 PM2.5 Plan, the EPA considers that the State 
procedures \116\ for estimating future design values for the 2012 
annual PM2.5 NAAQS generally followed the EPA's 
recommendations and are adequate.
---------------------------------------------------------------------------

    \116\ 2018 PM2.5 Plan, App. K, 18.
---------------------------------------------------------------------------

    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 2012 annual 
PM2.5 NAAQS using that same information, much of which has 
already been discussed in the EPA's 2006 NAAQS Modeling TSD. For the 
most part, in the EPA's 2006 NAAQS Modeling 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. That TSD did note a relatively large negative 
normalized bias (underprediction) in the ammonium and nitrate 
performance statistics \117\ 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.\118\ The RRF procedure removes much of 
this bias, so the underprediction in the model performance evaluation 
does not translate into an underpredicted 2025 design value. The EPA's 
2006 NAAQS Modeling TSD noted that because those quarters have 
projected concentrations that are less than half of those in the 1st 
and 4th, this may have a small influence on annual average 
concentrations. It has still 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 a for quarter 3, and occurred when 
quarterly total PM2.5 concentration was 9.4 [mu]g/m\3\. By 
contrast, for quarter 1 nitrate had a small overprediction, and 
occurred when quarterly total PM2.5 concentration was 21.1 
[mu]g/m\3\. That is, nitrate predictions have more bias during the 
quarters with low PM2.5 concentrations. This is apparent 
from the Plan's ``bugle'' plot for the four monitors with speciated 
data.\119\ Large (negative) values of bias in nitrate predictions occur 
for the lowest quarterly nitrate concentrations. For the higher 
concentrations that most affect the annual average, nitrate fractional 
bias has a mixture of positive and negative values. For total 
PM2.5, fractional bias has a similar seasonal pattern to 
that of nitrate, with underprediction during quarter 2 and quarter 3 
when quarterly PM2.5 concentration values are in the 5-10 
[mu]g/m\3\ range, and small bias when quarterly concentrations are in 
the 20-30 [mu]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.\120\
---------------------------------------------------------------------------

    \117\ Id. at App. K, 48ff, tables 20 through 23.
    \118\ Id. at App. K, 131ff, Supplemental materials, Figures 
S.41-S.52.
    \119\ Id. at App. K, 53, Figure 13.
    \120\ Id. at App. K, 54, 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 evaluated, in our rulemaking with respect to the 2006 24-
hour PM2.5 NAAQS in the SJV, the State's choice of model and 
the extensive discussion in the 2018 PM2.5 Plan about 
modeling procedures, tests, and performance analyses.\121\ We consider 
the State's analyses consistent with the EPA's guidance on modeling for 
PM2.5 attainment planning purposes. Based on these reviews, 
we propose to find that the modeling in the 2018 PM2.5 Plan 
is adequate for the purposes of supporting

[[Page 74324]]

the State's RFP demonstration and the attainment demonstration.
---------------------------------------------------------------------------

    \121\ For a more detailed summary of the State's air quality 
modeling in the 2018 PM2.5 Plan with respect to the 2006 
24-hour PM2.5 NAAQS, rather than the 2012 annual 
PM2.5 NAAQS, please refer to the EPA's 2006 NAAQS 
Modeling TSD.
---------------------------------------------------------------------------

D. Best Available Control Measures

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 the best available control measures (BACM) 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 4 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).'' \122\
---------------------------------------------------------------------------

    \122\ 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.
---------------------------------------------------------------------------

    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.\123\ Indeed, as implementation of BACM and BACT is 
required 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 costly level of 
control.\124\ If RACM and RACT level controls of emissions have been 
insufficient to reach attainment, the CAA contemplates the 
implementation of more stringent controls, controls on more sources, or 
other adjustments to the control strategy necessary to attain the NAAQS 
in the area.
---------------------------------------------------------------------------

    \123\ 81 FR 58010, 58081 and General Preamble Addendum, 42011, 
42013.
    \124\ Id. and General Preamble Addendum, 42009-42010.
---------------------------------------------------------------------------

    Consistent with longstanding guidance provided in the General 
Preamble Addendum, the preamble to the PM2.5 SIP 
Requirements Rule discusses the following steps for determining BACM 
and BACT:
    1. Develop a comprehensive emission inventory of the sources of 
PM2.5 and PM2.5 precursors;
    2. Identify potential control measures;
    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.\125\
---------------------------------------------------------------------------

    \125\ 81 FR 58010, 58083-58085.
---------------------------------------------------------------------------

    The EPA allows consideration of factors such as physical plant 
layout, energy requirements, needed infrastructure, and workforce type 
and habits when considering technological feasibility. For purposes of 
evaluating economic feasibility, the EPA allows consideration of 
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.\126\
---------------------------------------------------------------------------

    \126\ 40 CFR 51.1010(a)(3) and 81 FR 58010, 58041-58042.
---------------------------------------------------------------------------

    Once these analyses are complete, the state must use this 
information to develop enforceable control measures 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.
2. Summary of State's Submission
    As discussed in section IV.A of this proposed rule, Appendix B 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 SJV 
nonattainment area together with documentation to support these 
inventories. Each inventory includes emissions from stationary, area, 
on-road, and non-road emission sources, and the State specifically 
identifies the condensable component of direct PM2.5 for 
relevant stationary and area source categories. As discussed in section 
IV.B of this proposed rule concerning precursors, the State's analysis 
indicates that the Plan should control emissions of PM2.5 
and NOX in order to reach attainment. Accordingly, the State 
evaluated potential controls for those pollutants in the analysis of 
what is necessary to meet the BACM (including BACT) requirements.
    For stationary and area sources, the District identifies the 
sources of direct PM2.5 and NOX in the SJV that 
are subject to District emission 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 emission sources, and control measures implemented in 
other ozone and PM2.5 nonattainment areas in California and 
other states.\127\ Based on these analyses, the District concludes that 
all best available control measures for stationary and area sources are 
in place in the SJV for NOX and directly emitted 
PM2.5 for purposes of meeting the BACM/BACT requirement for 
the 2012 annual PM2.5 NAAQS.
---------------------------------------------------------------------------

    \127\ 2018 PM2.5 Plan, Ch. 4, section 4.3.1.
---------------------------------------------------------------------------

    For mobile sources, CARB identifies the sources of direct 
PM2.5 and NOX in the SJV that are subject to the 
State's emission control measures and provides its evaluation of these 
regulations for compliance with BACM requirements in Appendix D of the 
2018 PM2.5 Plan. Appendix D describes CARB's process for 
determining BACM, including identification of the sources of direct 
PM2.5 and NOX in the SJV, 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.\128\ CARB 
further discusses its current mobile source control program and 
additional mobile source measures in the Valley State SIP Strategy. 
Appendix D of the 2018 PM2.5 Plan also describes the current 
efforts of the eight local jurisdiction metropolitan planning 
organizations (MPOs) to implement cost-effective transportation control 
measures (TCMs) in the SJV.\129\ Based on these analyses, CARB 
concludes that all best available control measures for mobile sources 
are in place in the SJV for NOX and directly emitted 
PM2.5 for purposes of meeting the BACM/BACT requirement for 
the 2012 annual PM2.5 NAAQS.
---------------------------------------------------------------------------

    \128\ Id. at App. D, Ch. II.
    \129\ Id. at App. D, D-127 and D-128.

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[[Page 74325]]

3. EPA Evaluation and Proposed Action
    The first step in determining BACM is to develop a comprehensive 
emissions inventory of the sources of direct PM2.5 and 
relevant PM2.5 precursors that can be used with modeling to 
determine the effects of these sources on ambient PM2.5 
levels. Based on our review of the emission inventories provided in 
Appendix B of the 2018 PM2.5 Plan and the State's and 
District's identification of the sources subject to control in Appendix 
C and Appendix D, the EPA proposes to find that the Plan appropriately 
identifies all sources of direct PM2.5 and NOX 
that are subject to evaluation for potential control consistent with 
the requirements of subpart 4 of part D, title I of the Act.
    The remaining steps are to identify potential control measures for 
each source category, determine whether available control measures or 
technologies are technologically and economically feasible for 
implementation in the area, and determine the earliest date by which 
those control measures or technologies found to be feasible can be 
implemented, in whole or in part.\130\
---------------------------------------------------------------------------

    \130\ 81 FR 58010, 58083-58085. The EPA's recommended steps for 
a BACM demonstration are substantively similar to the required steps 
for an MSM demonstration in 40 CFR 51.1010(b).
---------------------------------------------------------------------------

    We provide an evaluation of many of the District's control measures 
for stationary sources and area sources in section III of the EPA's 
``Technical Support Document, EPA Evaluation, San Joaquin Valley 
Serious Area Plan for the 2012 Annual PM2.5 NAAQS,'' 
December 2021 (``EPA's 2012 Annual PM2.5 TSD'').
    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.\131\
---------------------------------------------------------------------------

    \131\ 2018 PM2.5 Plan, App. D, Table 17.
---------------------------------------------------------------------------

    Appendix D of the 2018 PM2.5 Plan describes the current 
efforts of the eight local jurisdiction MPOs to implement cost-
effective TCMs in the SJV.\132\ TCMs are projects that reduce air 
pollutants from transportation sources by reducing vehicle use, traffic 
congestion, or vehicle miles traveled. The eight MPOs in the SJV 
currently implement TCMs 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% 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.\133\ 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 SJV.\134\
---------------------------------------------------------------------------

    \132\ Id. at App. D, D-127 and D-128.
    \133\ Id. at App. D, D-127.
    \134\ Id. and SJVUAPCD, ``2016 Ozone Plan for 2008 8-Hour Ozone 
Standard'' (adopted June 16, 2016), App. D, Attachment D, tables D-
10 to D-17.
---------------------------------------------------------------------------

    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 2012 annual PM2.5 NAAQS. In our review, we 
considered our evaluation of the State's and District's rules in 
connection with our approval of the demonstrations for BACM (including 
BACT) and MSM for the 2006 24-hour PM2.5 NAAQS.\135\ We 
conclude that the evaluation processes followed by CARB and the 
District in the SJV PM2.5 Plan to identify potential BACM 
were 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 the eight MPOs are 
implementing all reasonable TCMs in the SJV and propose to find that 
these TCMs implement BACM for transportation sources.
---------------------------------------------------------------------------

    \135\ 85 FR 44192. The EPA provides a more detailed evaluation 
of many of the District's control measures for stationary and area 
sources in two supporting documents: 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; and 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.
---------------------------------------------------------------------------

    For the foregoing reasons, we propose to find that the SJV 
PM2.5 Plan provides for the implementation of BACM 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 the Serious area plan requirements 
for the 2012 annual PM2.5 NAAQS.

E. 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 standards in the area.\136\ 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). The publication of our final action to reclassify the SJV 
area as Serious nonattainment for the 2012 annual PM2.5 
NAAQS established a deadline of June 27, 2023, 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 2012 annual 
PM2.5 NAAQS.\137\
---------------------------------------------------------------------------

    \136\ General Preamble, 13539 and 13541-13542.
    \137\ 86 FR 67343, 67347.
---------------------------------------------------------------------------

    California submitted nonattainment NSR SIP revisions to address the 
subpart 4 requirements for the Serious area attainment plan for SJV on 
November 20, 2019.\138\ We will act on that submission through a 
separate rulemaking, as appropriate.
---------------------------------------------------------------------------

    \138\ Letter dated November 15, 2019, from Richard W. Corey, 
Executive Officer, CARB, to Michael Stoker, Regional Administrator, 
EPA Region IX.
---------------------------------------------------------------------------

F. Attainment Demonstration

1. Requirements for Attainment Demonstration
    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 relevant PM2.5 NAAQS by 
the applicable attainment date. The PM2.5 SIP Requirements 
Rule explains that Serious area attainment plans under CAA sections 
189(b) must include a demonstration (including air quality modeling) 
that the control

[[Page 74326]]

strategy provides for attainment of the PM2.5 NAAQS as 
expeditiously as practicable.\139\ 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 determined to be RACM, RACT, and 
additional reasonable measures, and BACM, BACT, and additional feasible 
measures), and any other emissions controls that are needed for 
expeditious attainment of the NAAQS.\140\ The regulatory requirements 
for Serious area plans are codified at 40 CFR 51.1010 (control strategy 
requirements) and 40 CFR 51.1011(b) (attainment demonstration and 
modeling requirements).
---------------------------------------------------------------------------

    \139\ 40 CFR 51.1011(b)(1); 81 FR 58010, 58087-58088.
    \140\ 40 CFR 51.1010(a); 81 FR 58010, 58089-58090.
---------------------------------------------------------------------------

2. Summary of State's Submission
    The SJV PM2.5 Plan includes a modeled demonstration 
projecting attainment of the 2012 annual PM2.5 NAAQS in the 
SJV by December 31, 2025, based on emission reductions from 
implementation of baseline control measures and the development, 
adoption, and implementation of additional control measures to meet 
specific enforceable commitments. We have summarized the State's air 
quality modeling for demonstrating attainment in section IV.C.2 of this 
proposed rule. Table 3 shows the 2013 base year and 2025 projected 
future year annual PM2.5 design values at monitoring sites 
in the SJV. As recommended by the EPA's guidance, the 2013 base year 
design value for modeling purposes is a weighted average of three 
monitored design values (for 2010-2012, 2011-2013, and 2012-2014), to 
minimize the influence of year-to-year variability. The highest 2025 
projected design value is 12.0 [mu]g/m\3\ at the Bakersfield-Planz and 
Madera monitoring sites, consistent with demonstrating attainment of 
the 12.0 [mu]g/m\3\ level of the 2012 annual PM2.5 
NAAQS.\141\
---------------------------------------------------------------------------

    \141\ As discussed in section IV.B.3.a of this proposed rule, 
the State notes that Madera concentrations are biased high. 2018 
PM2.5 Plan, App. G, 14.

  Table 3--Base Year and Projected Attainment Year Annual PM2.5 Design
          Values at Monitoring Sites in the San Joaquin Valley
------------------------------------------------------------------------
                                      2013 Base design   2025 Projected
           Monitoring site              value ([mu]g/     design value
                                            m\3\)         ([mu]g/m\3\)
------------------------------------------------------------------------
Bakersfield-Planz...................              17.2              12.0
Madera..............................              16.9              12.0
Hanford.............................              16.5              10.5
Visalia.............................              16.2              11.5
Clovis..............................              16.1              11.4
Bakersfield-California..............              16.0              11.0
Fresno-Garland......................              15.0              10.4
Turlock.............................              14.9              11.1
Fresno-Hamilton & Winery............              14.2              10.0
Stockton............................              13.1              10.6
Merced-S. Coffee....................              13.1               9.6
Modesto.............................              13.0               9.9
Merced-M Street.....................              11.0               8.6
Manteca.............................              10.1               8.0
Tranquility.........................               7.7               5.5
------------------------------------------------------------------------
Source: 2018 PM2.5 Plan, Table 7-3.

    The SJV PM2.5 Plan's control strategy to reduce 
emissions from sources of NOX and direct PM2.5 is 
presented in Chapter 4 (``Attainment Strategy for PM2.5'') 
\142\ and related supporting information in the Plan's control strategy 
appendices, including Appendix C (``Stationary Source Control Measure 
Analyses''), Appendix D (``Mobile Source Control Measures Analyses''), 
and Appendix E (``Incentive-Based Strategy''). Most of the projected 
emission reductions are achieved by baseline measures--i.e., the 
combination of State and District measures adopted prior to the State's 
and District's adoption of the Plan--that will achieve ongoing emission 
reductions from the 2013 base year to the 2025 projected attainment 
year.
---------------------------------------------------------------------------

    \142\ Consistent with the State and District's determination 
that ammonia, SOX, and VOC do not contribute 
significantly to PM2.5 levels exceeding the NAAQS in the 
SJV, the Plan's control strategy focuses on reductions in emissions 
of direct PM2.5 and NOX. CARB Staff Report, 
12. Nonetheless, the Plan projects the following annual average 
emission reductions from the 2013 base year to 2025: 0.5 tpd 
reductions in SOX (5.9%), 30.0 tpd reductions in VOC 
(9.3%), and 4.9 tpd reductions in ammonia (1.5%). 2018 
PM2.5 Plan, App. B, tables B-3, B-4, and B-5.
---------------------------------------------------------------------------

    The remainder of the emission reductions are to be achieved by 
additional measures to meet enforceable commitments, including 
potential regulatory and incentive-based measures and, as necessary, 
substitute measures.\143\ In the Valley State SIP Strategy and the 2018 
PM2.5 Plan, CARB and the District, respectively, included 
commitments to take action on specific measures by specific years or to 
develop substitute measures (referred to as ``control measure 
commitments'') and to achieve specified amounts of NOX and 
direct PM2.5 emission reductions by certain dates (referred 
to as ``aggregate tonnage commitments'').\144\ We refer to these 
complementary commitments herein as ``aggregate commitments.''
---------------------------------------------------------------------------

    \143\ In this proposed rule, the term ``substitute measures'' 
means additional control measures that were not identified in CARB 
and the District's original control measure commitments in adopting 
the Valley State SIP Strategy and the 2018 PM2.5 Plan, 
respectively. The ``substitute'' aspect primarily relates to 
emission reductions (i.e., providing emission reductions where any 
adopted measure achieves less emission reductions than originally 
estimated, and/or providing emission reductions in lieu of any 
originally planned measure that is not adopted). They are also 
sometimes referred to as ``alternative measures'' in the SJV 
PM2.5 Plan and adopting resolutions.
    \144\ CARB Resolution 18-49 and SJVUAPCD Governing Board 
Resolution 18-11-16, paragraph 6.

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

[[Page 74327]]

    CARB's control measure commitments include 12 regulatory measures 
and 3 incentive-based measures with implementation anticipated to start 
no later than 2024.\145\ The District's control measure commitments 
include nine regulatory measures and three incentive-based measures 
with implementation anticipated to start no later than 2024.\146\ We 
provide further detail on CARB and the District's control measure 
commitments both in sections IV.F.3.b and IV.F.3.c of this proposed 
rule and in section IV.A of the EPA's 2012 Annual PM2.5 TSD.
---------------------------------------------------------------------------

    \145\ Valley State SIP Strategy, Table 7. The schedule of 
proposed SIP measures in Table 7 includes two additional CARB 
measures: The second phase of the Advanced Clean Cars Program (``ACC 
2'') and the ``Cleaner In-Use Agricultural Equipment'' measures. 
However, these measures are not scheduled for implementation until 
2026 and 2030, respectively, which is after the January 1, 2025 
implementation deadline under 40 CFR 51.1011(b)(5) for control 
measures necessary for attainment by December 31, 2025. Therefore, 
we are not reviewing these measures as part of the control strategy 
to attain the 2012 annual PM2.5 NAAQS in the SJV.
    \146\ 2018 PM2.5 Plan, Ch. 4, tables 4-3 and 4-5.
---------------------------------------------------------------------------

    CARB's aggregate tonnage commitments are ``to achieve the aggregate 
emissions reductions outlined in the Valley State SIP Strategy of 32 
tpd of NOX and 0.9 tpd of PM2.5 emissions 
reductions in the San Joaquin Valley by 2024 and 2025.'' \147\ The 
Valley State SIP Strategy explains that CARB's overall commitment is to 
``achieve the total emission reductions necessary to attain the federal 
air quality standards, reflecting the combined reductions from the 
existing control strategy and new measures'' and that ``if a particular 
measure does not get its expected emissions reductions, the State is 
still committed to achieving the total aggregate emission reductions.'' 
\148\
---------------------------------------------------------------------------

    \147\ CARB Resolution 18-49.
    \148\ 2018 PM2.5 Plan, Ch. 4, 4-29.
---------------------------------------------------------------------------

    The District's aggregate tonnage commitments are to ``achieve the 
aggregate emissions reductions of 1.88 tpd of NOX and 1.3 
tpd of PM2.5 by 2024/2025'' through adoption and 
implementation of these measures or, if the total emission reductions 
from these rules or measures are less than these amounts, ``to adopt, 
submit, and implement substitute rules and measures that achieve 
equivalent reductions in emissions of direct PM2.5 or 
PM2.5 precursors'' in the same implementation 
timeframes.\149\
---------------------------------------------------------------------------

    \149\ SJVUAPCD Governing Board Resolution 18-11-16, paragraph 6.
---------------------------------------------------------------------------

    CARB and the District's aggregate tonnage commitments sum to 33.88 
tpd NOX and 2.2 tpd direct PM2.5 emission 
reductions. We provide further detail on CARB and the District's 
aggregate tonnage commitments in sections IV.F.3.b and IV.F.3.d of this 
proposed rule and in section IV.B of the EPA's 2012 Annual 
PM2.5 TSD.
    We note that the SJV PM2.5 Plan generally relies on 
annual average emission inventory and control strategy estimates, 
consistent with the annual average form of the 2012 annual 
PM2.5 NAAQS. 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 2012 annual PM2.5 NAAQS in 
the SJV by December 31, 2025.\150\
---------------------------------------------------------------------------

    \150\ Emission reductions from baseline measures are calculated 
as the sum of all stationary, area, and mobile source emission 
reductions from 2013 to 2025 in App. B of the 2018 PM2.5 
Plan.

   Table 4--Summary of the SJV PM2.5 Plan's Annual Average Emission Reductions To Attain the 2012 Annual PM2.5
                                           NAAQS by December 31, 2025
----------------------------------------------------------------------------------------------------------------
                                                                                                    % of 2013-
                                                                  % of 2013 base   Direct PM2.5      base year
                                                     NOX (tpd)       year NOX          (tpd)           PM2.5
                                                                     emissions                       emissions
----------------------------------------------------------------------------------------------------------------
A....................  2013 Base Year Emissions.           317.2  ..............            62.5  ..............
B....................  Baseline Measure Emission           173.5            54.7             4.2             6.7
                        Reductions (2013-2025).
C....................  Additional CARB Measures.              32            10.1             0.9             1.4
D....................  Additional District                  1.88             0.6             1.3             2.1
                        Measures.
E....................  Total 2013-2025 Emission           207.38            65.4             6.4            10.2
                        Reductions (B+C+D).
----------------------------------------------------------------------------------------------------------------
Source: 2018 PM2.5 Plan, Appendix B, tables B-1 and B-2, and Ch. 4, tables 4-3 and 4-7.

3. EPA Evaluation and Proposed Action
    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 proposed rule, the EPA 
proposes to approve the emissions inventories on which the State based 
the SJV PM2.5 Plan's attainment demonstration and related 
provisions. Furthermore, as discussed in section IV.C of this proposed 
rule, the EPA has evaluated the State's choice of model and the 
extensive discussion in the Modeling Protocol about modeling 
procedures, tests, and performance analyses. We consider the analyses 
consistent with the EPA's guidance on modeling for PM2.5 
attainment planning purposes. Based on these reviews, we propose to 
find that the modeling in the Plan is adequate for the purposes of 
supporting the RFP demonstration and demonstration of attainment by 
2025, and thus propose to approve the air quality modeling. For further 
detail, see the EPA's February 2020 Modeling TSD.
    Second, we must find that the attainment plan SIP submission 
provides for expeditious attainment through the timely implementation 
of the control strategy, including RACM, BACM, and any other emission 
controls that are needed for expeditious attainment. In the EPA's final 
rule on the SJV Moderate area plan for the 2012 annual PM2.5 
NAAQS, the EPA approved the State's demonstration of RACM (including 
RACT) and additional reasonable measures for all sources of direct 
PM2.5 and NOX, under CAA section 189(a)(1)(C) and 
40 CFR 51.1009 for purposes of the 2012 annual PM2.5 
NAAQS.\151\ As discussed in section IV.C of this proposed rule, the EPA 
now proposes to approve the SJV PM2.5 Plan's demonstration 
of BACM (including BACT) under CAA section 189(b)(1)(B).
---------------------------------------------------------------------------

    \151\ Our approval of the State's demonstration of RACM and 
additional reasonable measures was informed by the State's control 
stringency demonstrations in both the Moderate area plan (2016 
PM2.5 Plan) and the Serious area plan (2018 
PM2.5 Plan) for the 2012 annual PM2.5 NAAQS in 
the SJV. 86 FR 49100, 49115-49116.
---------------------------------------------------------------------------

    Third, the EPA must find that the emissions reductions that are 
relied on

[[Page 74328]]

for attainment in the SIP submission are creditable. As discussed in 
subsections IV.F.3.a through IV.F.3.e of this proposed rule, the SJV 
PM2.5 Plan relies principally on already adopted and 
approved rules to achieve the emissions reductions needed to attain the 
2012 annual PM2.5 NAAQS in the SJV by December 31, 2025. The 
balance of the reductions that the State has modeled to achieve 
attainment by this date is currently represented by enforceable 
commitments that account for 13.8% of the NOX and 8.0% 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 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 commitments constitute a 
limited portion of the required emissions reductions, (2) both the 
State and the District have demonstrated their capability to meet their 
commitments, and (3) the commitments are for an appropriate timeframe. 
We therefore propose to approve the State's reliance on these 
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 2012 annual 
PM2.5 NAAQS by December 31, 2025, consistent with the 
requirements of CAA sections 189(b)(1)(A). We present the basis for 
this proposed determination in subsections IV.F.3.a through IV.F.3.e of 
this proposal and provide further detail of our evaluation of baseline 
measures and the additional measures and aggregate commitments in 
sections II and IV, respectively, of the EPA's 2012 Annual 
PM2.5 TSD. In the following subsections we first address the 
baseline measures that are in effect in the SJV; we then describe the 
control measure and aggregate tonnage commitments submitted with the 
Plan; next, we evaluate progress that the State and District have made 
since submission of the Plan, on both the control measures and the 
aggregate tonnage commitments; finally we apply the three-factor test 
for reliance on enforceable commitments to demonstrate attainment.
(a) Baseline Measures
    Baseline measures will provide the majority of emissions reductions 
needed to attain the 2012 annual PM2.5 NAAQS in the SJV, 
amounting to approximately 83.7% of the total NOX emission 
reductions and 65.6% of the total direct PM2.5 emission 
reductions necessary to attain.\152\
---------------------------------------------------------------------------

    \152\ The EPA calculated these percentages as follows: Annual 
average baseline NOX reductions from 2013 to 2025 are 
173.5 tpd of 207.38 tpd modeled to result in attainment (83.7%) and 
annual average baseline direct PM2.5 reductions are 4.1 
tpd of 6.3 tpd modeled to result in attainment (65.1%). 2018 
PM2.5 Plan, Ch. 4 and App. B.
---------------------------------------------------------------------------

    In the 2018 PM2.5 Plan, the State explains that mobile 
sources emit over 85% of the NOX in the SJV and that CARB 
has adopted and amended regulations to reduce public exposure to diesel 
particulate matter, which includes 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.'' 
\153\
---------------------------------------------------------------------------

    \153\ 2018 PM2.5 Plan, Ch. 4, 4-9 and Valley State 
SIP Strategy, 4. For CARB's analysis of its mobile source measures 
for BACM and MSM, see 2018 PM2.5 Plan, App. D, including 
analyses for on-road light-duty vehicles and fuels (starting page D-
17), on-road heavy-duty vehicles and fuels (starting page D-35), and 
non-road sources (starting 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 approved multiple mobile source 
regulations for which waivers or authorizations have been issued as 
revisions to the California SIP.\154\
---------------------------------------------------------------------------

    \154\ See, e.g., 81 FR 39424, 82 FR 14447, and 83 FR 23232.
---------------------------------------------------------------------------

    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 and approved as revisions to 
the California SIP.\155\
---------------------------------------------------------------------------

    \155\ See, e.g., 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 sources, in the 2018 PM2.5 Plan, the 
State explains that stringent regulations adopted for prior attainment 
plans continue to reduce emissions of NOX and direct 
PM2.5.\156\ Specifically, Table 4-1 of the 2018 
PM2.5 Plan (``District Rules Reducing PM and NOX 
Emissions in the Valley'') identifies 33 District measures that limit 
NOX and direct PM2.5 emissions.\157\ The EPA has 
approved each of the identified measures into the California SIP,\158\ 
with two exceptions.
---------------------------------------------------------------------------

    \156\ 2018 PM2.5 Plan, Ch. 4, 4-3. For the District's 
analysis of its stationary source measures for BACM and MSM, see 
2018 PM2.5 Plan, App. C.
    \157\ Id. at Ch. 4, Table 4-1.
    \158\ 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 emission fees in lieu of 
meeting the rule's NOX emission limits.\159\ CARB submitted 
the amended rule to the EPA on November 21, 2018. However, the District 
amended Rule 4905 once more on October 15, 2020, to further extend the 
period during which manufacturers of weatherized furnaces may pay 
emission fees in lieu of meeting the rule's NOX emission 
limits.\160\ CARB submitted the rule as amended October 15, 2020, to 
the EPA on December 30, 2020, and simultaneously withdrew the rule as 
amended June 21, 2018.\161\ The EPA has not yet proposed any action on 
this submission.
---------------------------------------------------------------------------

    \159\ SJVUAPCD, Final Draft Staff Report, ``Proposed Amendments 
to Rule 4905 (Natural Gas-fired, Fan-type Central Furnaces),'' 2.
    \160\ SJVUAPCD, ``Item Number X: Adopt Proposed Amendments to 
Rule 4905 (Natural Gas-Fired, Fan-Type Furnaces),'' October 15, 
2020, 3, including Final Draft Staff Report, ``Proposed Amendments 
to Rule 4905 (Natural Gas-Fired, Fan-Type Furnaces).''
    \161\ Letter dated December 28, 2020, from Richard W. Corey, 
Executive Officer, CARB, to John Busterud, Regional Administrator, 
EPA Region IX.
---------------------------------------------------------------------------

    The EPA approved a prior version of Rule 4905 into the California 
SIP on March 29, 2016.\162\ 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 emission limits, emission reductions associated with 
the rule's emission limits would not be creditable in any attainment 
plan without additional documentation.\163\ Until the District submits 
the necessary documentation to credit emission reductions achieved by 
Rule 4905

[[Page 74329]]

toward an attainment control strategy, this rule is not creditable for 
SIP purposes. The 2018 PM2.5 Plan indicates that the 
District attributed annual average emission reductions of 0.31 tpd 
NOX between 2013 and 2025 to Rule 4905.\164\ These emission 
reductions would not materially affect the attainment demonstration in 
the SJV PM2.5 Plan.
---------------------------------------------------------------------------

    \162\ 81 FR 17390 (March 29, 2016) (approving Rule 4905 as 
amended January 22, 2015).
    \163\ EPA Region IX, ``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.
    \164\ 2018 PM2.5 Plan, App. C, C-290.
---------------------------------------------------------------------------

    Second, the 2018 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.\165\ 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 2025.\166\ Thus, although the 
District included this rule as a baseline measure, there are no 
meaningful reductions associated with this rule that would affect the 
attainment demonstration in the SJV PM2.5 Plan.
---------------------------------------------------------------------------

    \165\ The EPA does not have any pending SIP submission for Rule 
4203.
    \166\ 2018 PM2.5 Plan, App. C, C-46.
---------------------------------------------------------------------------

    In sum, although Table 4-1 of the 2018 PM2.5 Plan 
identifies two baseline measures that are not creditable for SIP 
purposes at this time, we conclude that the total emission reductions 
attributed to these two measures in the future baseline inventories 
would not materially affect the attainment demonstration in the Plan.
(b) Additional Measures and Aggregate Commitments
    The SJV PM2.5 Plan identifies a series of additional 
CARB and District commitments to achieve emission reductions through 
additional control measures beyond baseline measures that will 
contribute to expeditious attainment of the 2012 annual 
PM2.5 NAAQS. As discussed in section IV.F.2 of this proposed 
rule, for mobile sources, CARB's commitment identifies a list of 12 
State regulatory measures and 3 incentive-based measures that CARB has 
committed to propose to its Board for consideration by specific 
years.\167\ For stationary sources, the District's commitment 
identifies a list of nine regulatory measures and three incentive-based 
measures that the District has committed to propose to its Board for 
consideration by specific years.\168\ The Plan contains CARB and the 
District's estimates of the emission reductions that would be achieved 
by each of these additional measures, if adopted.\169\
---------------------------------------------------------------------------

    \167\ CARB Resolution 18-49, Attachment A and Valley State SIP 
Strategy, Table 7 (``State Measures and Schedule for the San Joaquin 
Valley'').
    \168\ SJVUAPCD Governing Board Resolution 18-11-16 and 2018 
PM2.5 Plan, Table 4-4 (``Proposed Regulatory Measures'') 
and Table 4-5 (``Proposed Incentive-Based Measures'').
    \169\ 2018 PM2.5 Plan, Ch. 4, Table 4-3 (''Emission 
Reductions from District Measures'') and Table 4-9 (''San Joaquin 
Valley Expected Emission Reductions from State Measures'') and 
Valley State SIP Strategy, Table 8 (``San Joaquin Valley Expected 
Emission Reductions from State Measures'').
---------------------------------------------------------------------------

    CARB's commitments are contained in CARB Resolution 18-49 (October 
25, 2018) and the Valley State SIP Strategy and consist of two parts: A 
control measure commitment and a tonnage commitment. First, CARB has 
committed to ``begin the measure's public process and bring to the 
Board for 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.'' \170\ By email dated November 12, 2019, 
CARB confirmed that it intended to begin the public process on each 
measure by discussing the proposed regulation or program at a public 
meeting (workshop, working group, or Board hearing) or in a publicly-
released document and to then propose the regulation or program to its 
Board.\171\ Second, CARB has committed ``to achieve the aggregate 
emissions reductions outlined in the Valley State SIP Strategy of 32 
tpd of NOX and 0.9 tpd of PM2.5 emissions 
reductions in the San Joaquin Valley by 2024 and 2025.'' \172\ The 
Valley State SIP Strategy explains that CARB's overall commitment is to 
``achieve the total emission reductions necessary to attain the federal 
air quality standards, reflecting the combined reductions from the 
existing control strategy and new measures'' and that ``if a particular 
measure does not get its expected emissions reductions, the State is 
still committed to achieving the total aggregate emission reductions.'' 
\173\
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    \170\ CARB Resolution 18-49, 5.
    \171\ 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 
CARB Staff Report, 14.
    \172\ CARB Resolution 18-49, 5.
    \173\ Valley State SIP Strategy, 7.
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    The District's commitments are contained in SJVUAPCD Governing 
Board Resolution 18-11-16 (November 15, 2018) and Chapter 4 of the 2018 
PM2.5 Plan and similarly consist of two parts: A control 
measure commitment and a tonnage commitment. First, the District has 
committed to ``take action on the rules and measures committed to in 
Chapter 4 of the Plan by the dates specified therein, and to submit 
these rules and measures, as appropriate, to CARB within 30 days of 
adoption for transmittal to EPA as a revision to the [SIP].'' \174\ By 
email dated November 12, 2019, the District confirmed that it intended 
to take action on the listed rules and measures by beginning the public 
process on each measure, i.e., discussing the proposed regulation or 
program at a public meeting, including a workshop, working group, or 
Board hearing, or in a publicly-released document, and then proposing 
the rule or measure to the SJVUAPCD Governing Board.\175\ Second, the 
District has committed to ``achieve the aggregate emissions reductions 
of 1.88 tpd of NOX and 1.3 tpd of PM2.5 by 2024/
2025'' through adoption and implementation of these measures or, if the 
total emission reductions from these rules or measures are less than 
these amounts, ``to adopt, submit, and implement substitute rules and 
measures that achieve equivalent reductions in emissions of direct 
PM2.5 or PM2.5 precursors'' in the same 
implementation timeframes.\176\
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    \174\ SJVUAPCD Governing Board Resolution 18-11-16, 10-11.
    \175\ 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'').
    \176\ SJVUAPCD Governing Board Resolution 18-11-16, 10-11.
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(c) Progress on Control Measure Commitments
    In October 2021, CARB and the District provided the ``Progress 
Report and Technical Submittal for the 2012 PM2.5 Standard 
San Joaquin Valley'' (2021 Progress Report) to describe their progress 
to date in developing and adopting the additional measures identified 
in their control measure commitments. 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.\177\ It also provides a side-by-side comparison of the 
original emission reduction estimates in the SJV PM2.5 Plan 
for each control measure commitment and updated emission reduction 
estimates for each based on technical analyses for adopted measures and 
draft measures and/or

[[Page 74330]]

documentation in development for forthcoming regulations.\178\
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    \177\ ``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.''
    \178\ 2021 Progress Report, tables 2 and 3.
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    Together, as of December 2021, CARB and the District together have 
adopted 18 measures of the 27 control measure commitments in the SJV 
PM2.5 Plan and have begun the public process on 5 of the 
remaining control measure commitments. For CARB's portion, CARB has 
adopted 10 of the 15 measures in its commitment (including one 
incentive-based measure) and begun the public process on 3 of its 
remaining 5 measures. The adopted measures include, for example, the 
Heavy-Duty Vehicle Inspection and Maintenance Program (``Heavy-Duty I/
M''), the California Heavy-Duty Low-NOX Engine Standard, the 
Small Off-Road Engines (SORE) regulation, and the Accelerated Turnover 
of Agricultural Equipment Incentive Projects (``Agricultural Equipment 
Incentive Measure''). For the District's portion of the control measure 
commitments, the District has adopted 8 of the 12 measures in its 
commitment (including one incentive-based measure) and begun the public 
process on two of the remaining four measures. The adopted measures 
include, for example, amendments to Rule 4311 (``Flares''), Rule 4702 
(``Internal Combustion Engines''), and Rule 4901 (``Woodburning 
Fireplaces and Wood Burning Heaters'') (Hot-spot strategy), and the 
Residential Wood Burning Devices Incentive Projects measure.
    Accordingly, the EPA considers that, although CARB and the District 
have not met the commitment deadlines for several measures, as 
discussed further in this proposed rule, they have nonetheless made 
substantial progress in developing and adopting the regulatory measures 
listed in their respective control measure commitments. We provide 
further detail on CARB and the District's control measure commitments 
in section IV.A of the EPA's 2012 Annual PM2.5 TSD 
(including tables IV-A and IV-B regarding CARB and the District's 
control measure commitments, respectively).
    Regarding the remaining nine measures not yet proposed for board 
consideration, we note that one measure, Rule 4550 (``Conservation 
Management Practices''), has an action year of 2022 in the 2018 
PM2.5 Plan (i.e., it is not yet due for board consideration) 
and that four regulatory measures and four incentive-based measures are 
overdue.
    The four overdue regulatory measures are: The Zero-Emission Airport 
Ground Support Equipment measure; the Zero-Emission Off-Road Forklift 
Regulation Phase 1 measure; the Low-emission Diesel Fuel Requirement; 
and Rule 4692 (``Commercial Under-fired Charbroiling (Hot-spot 
Strategy)''). While they have not proposed these measures to their 
respective boards, CARB and the District timely began the public 
process on each of the four measures. CARB anticipates board 
consideration of the diesel fuel measures in 2022 and the forklift 
measure as early as 2022 and continues to develop the airport ground 
support equipment measure. The District adopted the ``Commercial 
Underfired Charbroiling Emission Reduction Strategy'' on December 17, 
2020, and continues to evaluate potential amendments to Rule 4692 in 
the near future.\179\
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    \179\ Id. at 8-9, 20-22, and tables 2 and 3.
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    The four overdue incentive-based control measures are for the 
Accelerated Turnover of Trucks and Buses Incentive Projects, the 
Accelerated Turnover of Off-road Equipment Incentive Projects, the 
Agricultural Operation Internal Combustion Engines Incentive Projects, 
and the Commercial Under-fired Charbroiling Incentive Projects. CARB 
and the District continue to invest in reducing emissions from these 
sources, as well as other incentive programs not named among the 27 
control measure commitments, such as those for nut harvesting and 
landscape maintenance equipment.\180\ However, while CARB and the 
District have discussed the proposed programs at certain board 
hearings,\181\ the EPA is not aware that CARB or the District have 
started public process for the four incentive-based control measure 
commitments as enforceable measures to be submitted for inclusion as 
control measures in the California SIP.
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    \180\ CARB, ``Long-Term Heavy-Duty Investment Strategy, 
Including Fiscal Year 2020-21 Three-Year Recommendations for Low 
Carbon Transportation Investments,'' (App. D to CARB's ``Proposed 
Fiscal Year 2021-22 Funding Plan for Clean Transportation 
Incentives''), release date October 8, 2021; and SJVUAPCD, 
``Comprehensive Annual Financial Report, Fiscal Year Ended June 30, 
2020,'' release date December 23, 2020. See also, 2021 Progress 
Report, 3 and 15.
    \181\ For example, CARB staff discussed the Accelerated Turnover 
of Trucks and Buses Incentive Measure at its annual 2020 update to 
the CARB Board. CARB presentation, ``Update on the 2018 
PM2.5 SIP for the San Joaquin Valley,'' October 22, 2020. 
District staff discussed and adopted an emission reductions strategy 
for commercial under-fired charbroiling, including incentives, in 
December 2020. SJVUAPCD, ``Item Number 11: Adopt Proposed Commercial 
Under-Fired Charbroiling Emission Reduction Strategy,'' December 17, 
2020.
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    Notwithstanding being overdue in presenting these incentive-based 
measures for board consideration, CARB and the District state that they 
continue to assess and/or prepare the formal documentation for the 
emission reductions from such incentive-based measures that could be 
applied towards the aggregate tonnage commitments.\182\ For heavy-duty 
trucks and off-road equipment, CARB acknowledges that many of the 
project lives do not span the attainment year \183\ and, thus, while 
these projects accelerate emission reductions and benefit communities 
in the SJV, the projects that qualify for SIP credit may be limited for 
the purposes of the 2012 annual PM2.5 NAAQS Serious area 
attainment demonstration. Overall, the EPA anticipates that emission 
reductions from such projects that qualify for SIP credit (``SIP-
creditable emission reductions'') may be smaller than originally 
anticipated in the SJV PM2.5 Plan.
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    \182\ 2021 Progress Report, 15 and 24.
    \183\ Id. at 24 and 32. Generally, mobile source incentive 
projects implemented under the Carl Moyer program are under contract 
only during the ``project life'' and may not be credited with SIP 
emission reductions after the project life ends. 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, 12-13.
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    CARB and the District point to certain measures that they 
anticipate will provide more emission reductions than the original 
emission reduction estimates (e.g., larger emission reductions from 
Heavy-Duty I/M due to new 2019 state law requirements and new roadside 
emissions monitoring) and the addition of the two substitute measures 
(the Agricultural Burning Phase-out Measure (adopted) and the In-Use 
Locomotive Measure (anticipated for CARB board consideration in 2022)) 
as compensating for incentive-based measures that may result in less 
emission reductions than originally projected.\184\ In its annual 
update to the Board on September 23, 2021, CARB staff explained that, 
in light of the progress to-date on committed-to regulatory measures 
and these two substitute measures, fewer incentive-based emission 
reductions would be needed to demonstrate attainment of the 2012 annual 
PM2.5 NAAQS.\185\ We further discuss the role of adopted 
measures, measures not yet proposed for board consideration (including 
incentive-based measures), and the substitute measures in the following 
section of this proposed rule.
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    \184\ 2021 Progress Report, 30-31.
    \185\ CARB, ``Valley PM2.5 Implementation Update and 
SIP Amendment,'' September 23, 2021, slides 22-25. Slide 25 
illustrates a large decrease in the expected funding need from 
approximately $5 billion over 2018-2025 to approximately $1 billion 
over 2021-2025.

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[[Page 74331]]

(d) Progress on Aggregate Tonnage Commitments
    As described in section IV.F.2 of this proposed rule, to attain the 
2012 annual PM2.5 NAAQS in the SJV, CARB committed to 
achieve 32 tpd of NOX and 0.9 tpd of PM2.5 
emissions reductions, and the District committed to achieve 1.88 tpd of 
NOX and 1.3 tpd of PM2.5 emissions reductions by 
2025. These aggregate tonnage commitments sum to 33.88 tpd 
NOX and 2.2 tpd direct PM2.5.
    As described in sections IV.F.3.b and IV.F.3.c of this proposed 
rule, CARB and the District have committed to achieve these reductions 
via the 27 control measure commitments, or such other substitute 
measures as may be necessary, to achieve the aggregate tonnage 
commitments for NOX and direct PM2.5. Because the 
State's efforts are ongoing, different control measures are at 
different stages of rule development, rule adoption, submission to the 
EPA, and EPA evaluation and rulemaking. For the purpose of our analysis 
of the State's progress toward achieving its aggregate tonnage 
commitments, we propose to credit reductions from rules that the EPA 
has approved into the SIP, or that EPA has proposed for approval into 
the SIP at the time of this notice. We begin by explaining these 
measures and summing the total reductions from such measures that can 
be credited to CARB and the District's aggregate commitments. For many 
remaining measures, although reductions are not formally SIP credited 
at this time, CARB and the District have made substantial progress 
toward achieving SIP approval, or otherwise advanced their analysis of 
the reductions they are likely to achieve in certain areas since the 
adoption of the Plan. Much of this progress is summarized in the 2021 
Progress Report. After detailing the creditable emission reductions 
achieved in approved rules and rules proposed for approval, we next 
address the State's progress on emission reductions from its remaining 
rule development efforts.
    Of the 18 measures adopted to date, as well as the adoption of an 
important substitute measure (the Agricultural Burning Phase-out 
Measure), the State has submitted 9 measures as revisions to the 
California SIP as of November 2021. The EPA has proposed or finalized 
action on four of these submitted measures, including three with large 
associated emission reductions of direct PM2.5 and/or 
NOX in the SJV, as follows.\186\
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    \186\ The additional measures submitted as SIP revisions for 
which the EPA has not proposed action include: The Innovative Clean 
Transit measure (submitted February 13, 2020); Rules 4311, 4306, and 
4320 (submitted March 12, 2021); and Rule 4702 (submitted October 
15, 2021).
---------------------------------------------------------------------------

    First, on July 22, 2020, the EPA published its final approval of 
the District's 2019 amendment to Rule 4901 \187\ 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 for 2024.\188\ As described in the EPA's March 27, 
2020 proposed rule, this amount of SIP credit corresponded to a 75% 
compliance rate (referred to as a ``rule effectiveness rate''), 
consistent with the EPA's guidance on wood burning curtailment 
programs,\189\ rather than a higher 100% rule effectiveness rate used 
in the District's original calculations.\190\ 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.\191\ 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 2025 (i.e., to subtract 0.2 tpd 
from the reductions of direct PM2.5 emissions that the 
District is required to achieve with its PM2.5 tonnage 
commitment).
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    \187\ 85 FR 44206.
    \188\ 85 FR 44192, 44204.
    \189\ ``Strategies for Reducing Wood Smoke,'' EPA-456/B-13-01, 
March 2013, 42.
    \190\ 85 FR 17382, 17415.
    \191\ 2021 Progress Report, 7 and Table 3.
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    Second, on March 24, 2020, the EPA published its proposal to 
approve the Agricultural Equipment Incentive Measure into the 
California SIP,\192\ including projects funded through the Carl Moyer 
Memorial Air Quality Standards Attainment Program (``Carl Moyer''), 
Funding Agricultural Replacement Measures for Emission Reductions 
(FARMER), and Natural Resources Conservation Service (NRCS) programs. 
The measure 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.\193\ 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).\194\
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    \192\ 85 FR 16588.
    \193\ 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, 4-5, 24-25, and 31.
    \194\ EPA Region IX, ``Air Plan Approval; San Joaquin Valley 
Unified Air Pollution Control District,'' final rule signed December 
16, 2021. The EPA deferred action on the NRCS portion of the 
Agricultural Equipment Incentive Measure.
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    Under longstanding guidance, the EPA has recommended presumptive 
limits on the amounts of emission reductions from certain voluntary and 
other nontraditional measures that may be credited in a SIP. 
Specifically, for voluntary mobile source emission reduction programs, 
the EPA has identified a presumptive limit of 3% of the additional 
emission reductions (beyond reductions from baseline measures) required 
to attain the appropriate NAAQS, and for any particular SIP submittal 
to demonstrate attainment or maintenance of the NAAQS or progress 
toward attainment (RFP), 3% of the specific statutory requirement.\195\ 
The EPA may, however, approve measures for SIP credit in amounts 
exceeding the presumptive limits where a clear and convincing 
justification is made by the State as to why a higher limit should 
apply in a given case.\196\
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    \195\ EPA, ``Guidance on Incorporating Voluntary Mobile Source 
Emission Reduction Programs in State Implementation Plans (SIPs),'' 
October 24, 1997, 5.
    \196\ EPA, ``Incorporating Emerging and Voluntary Measures in a 
State Implementation Plan (SIP),'' October 4, 2004, 9; see also EPA, 
``Guidance on Incorporating Bundled Measures in a State 
Implementation Plan,'' August 16, 2005, 8, n.6, and EPA, ``Diesel 
Retrofit and Replacement Projects: Quantifying and Using Their 
Emission Benefits in SIPs and Conformity: Guidance for State and 
Local Air and Transportation Agencies,'' March 2018, 12.
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    According to the State, the SJV's topography and meteorology 
present significant challenges for air quality. As stated in the 2018 
PM2.5 Plan, ``the surrounding mountains trap pollution and 
block airflow'' and ``[t]emperature inversions, while present to some 
degree throughout the year, can last for days during the winter, 
holding in nighttime accumulations of pollutants.'' \197\ In addition, 
the State notes that the population of the area continues to grow at a 
rate higher than the statewide growth rate, leading to increased 
vehicular traffic along major highways that run through the SJV.\198\ 
Given these unique challenges, both the State and District continue to 
implement both traditional and non-traditional emission reduction 
strategies to attain the PM2.5 standards in the SJV,

[[Page 74332]]

including regulatory programs, incentive programs, and rigorous 
outreach and education efforts.\199\
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    \197\ 2018 PM2.5 Plan, Ch. 2, 2-1.
    \198\ Id. at Ch. 2, 2-4.
    \199\ Id. at Ch. 2, 2-2.
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    Over the past several decades, the State and District have 
developed and implemented several comprehensive plans to address 
attainment of the NAAQS for ozone and particulate matter.\200\ These 
attainment plans have resulted in CARB and District's adoption of 
numerous regulations for stationary, area, and mobile sources, many of 
which are among the most stringent control measures in the nation. 
Given the air quality needs of the area, the numerous control measures 
that both the State and District have adopted and implemented in the 
San Joaquin Valley to date, the State's and District's successful 
implementation of the Carl Moyer program over the last two decades, and 
our experience to date quantifying emission reductions achieved through 
this program,\201\ we believe it is appropriate to allow the State to 
rely on the Agricultural Equipment Incentive Measure to achieve 13.2% 
(4.46 tpd) of the additional NOX reductions and 11.8% (0.26 
tpd) of the additional direct PM2.5 reductions necessary for 
the area to attain the 2012 annual PM2.5 NAAQS by the end of 
2025.\202\ Moreover, all Carl Moyer and FARMER projects are subject to 
detailed contract provisions that CARB may enforce against the grantee 
at any time during the contract term, a program feature that further 
supports the State's reliance on the Agricultural Equipment Incentive 
Measure for emission reductions exceeding the EPA's presumptive 
limits.\203\
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    \200\ See, e.g., 69 FR 30005 (May 26, 2004) (approving plan to 
attain the 1987 PM10 NAAQS), 76 FR 69896 (November 9, 
2011) (partially approving and partially disapproving plan to attain 
the 1997 PM2.5 NAAQS), 77 FR 12652 (March 1, 2012) 
(approving plan to attain the 1997 8-hour ozone NAAQS), and 81 FR 
19492 (April 5, 2016) (approving plan to attain the 1979 1-hour 
ozone NAAQS).
    \201\ The EPA has approved two prior incentive-based SIP 
submissions from CARB that rely on Carl Moyer projects for SIP 
emission reduction credit. See 86 FR 3820 (January 15, 2021) (full 
approval of South Coast incentive measure) and 81 FR 53300 (August 
12, 2016) (limited approval/disapproval of ``Emission Reduction 
Report'' for San Joaquin Valley).
    \202\ The EPA calculated these percentages based on the 
additional emission reductions necessary to attain beyond the 
baseline inventory for 2025: 4.46 tpd NOX/33.88 tpd 
NOX = 13.2%; and 0.26 tpd direct PM2.5/2.2 tpd 
direct PM2.5 = 11.8%.
    \203\ 2011 Carl Moyer Guidelines, Part I, Chapter 3, Section Y 
(``Minimum Contract Requirements'') and 2017 Carl Moyer Guidelines, 
Volume I, Part 1, Chapter 3, Section V (``Minimum Contract 
Requirements''), para. 11 (``Repercussions for Nonperformance'').
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    For purposes of the EPA's proposed rule on the Serious area plan 
for the 2012 annual PM2.5 NAAQS, we propose to approve 4.46 
tpd NOX and 0.26 tpd direct PM2.5 for the Carl 
Moyer and FARMER portions of this measure towards CARB's tonnage 
commitments for 2025 (for attaining the 2012 annual PM2.5 
NAAQS).
    Third, CARB adopted the Lower Opacity Limits for Heavy-Duty 
Vehicles measure as revisions to the Heavy-Duty Vehicle Inspection 
Program (HDVIP) and Periodic Smoke Inspection Program (PSIP). CARB 
estimated 1,170 tons of PM emissions benefits from the heavy-duty 
trucking transportation sector from 2019 to 2025.\204\ CARB also 
estimates that this measure will achieve 0.02 tpd direct 
PM2.5 reductions by January 1, 2025.\205\ However, CARB has 
not yet provided its analysis of the basis for this emission reduction 
estimate. Therefore the EPA is not proposing at this time to credit 
this measure with any particular amount of emission reductions towards 
attainment of the 2012 annual PM2.5 NAAQS in the SJV.
---------------------------------------------------------------------------

    \204\ 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, 
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, 4.
    \205\ 2021 Progress Report, 16 and Table 2.
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    Fourth, the Agricultural Burning Phase-out Measure is a significant 
substitute measure that was not part of the State's original control 
measure commitments. The Agricultural Burning Phase-out Measure, for 
purposes of state law, was adopted by the District on June 17, 
2021,\206\ and concurred upon by CARB on June 18, 2021,\207\ and later 
adopted by the District on November 18, 2021, as a revision to the 
California SIP.\208\ 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.\209\ The EPA approved Rule 4103 and the associated 
table of the restrictions on open burning by crop category into the 
California SIP on January 4, 2012.\210\ The District identifies Rule 
4103 as a baseline measure in the 2018 PM2.5 Plan.\211\ 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.\212\ The 
District estimates that this measure will achieve emission reductions 
of 1.04 tpd NOX and 1.54 tpd direct PM2.5 in 
2025.\213\
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    \206\ SJVUAPCD Resolution 21-06-12, June 17, 2021.
    \207\ Letter dated June 18, 2021, from Richard W. Corey, 
Executive Officer, CARB, to Samir Sheikh, Executive Director, 
SJVUAPCD.
    \208\ 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.
    \209\ SJVUAPCD Rule 4103, as amended April 15, 2010.
    \210\ 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.
    \211\ 2018 PM2.5 Plan, Chapter 4, tables 4-2 and 4-3, 
and App. C.
    \212\ 2021 Supplemental Report and Recommendations, Table 2-1 
(``Accelerated Reductions by Crop Category'').
    \213\ SJVUAPCD, ``District 4103 (Open Burning) Technical 
Submittal for Receiving SIP Credit for Reductions in Agricultural 
Burning,'' October 18, 2021, Table 6. See also, Progress Report, 
Table 3.
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    The EPA has evaluated this measure and has proposed to approve the 
measure into the California SIP.\214\ The EPA considers the 
Agricultural Burning Phase-out Measure to be an important new measure 
given the phase-out structure of the measure for most remaining crop 
categories and the large scale of agricultural activities that produce 
such agricultural waste and burning thereof in the SJV. While the 
District assumed a 100% rule effectiveness rate, the EPA noted our 
general guideline of 80% rule effectiveness and that, notwithstanding 
the statements in the 2021 Progress Report regarding the permitting 
requirements for farming operations to burn their waste and the 
enforceability of the measure, the District did not apply a rule 
effectiveness rate nor address all the factors that are relevant to 
determining such a rate.\215\ Therefore, the EPA proposes that an 80% 
rule effectiveness is reasonable for this measure.
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    \214\ EPA Region IX, ``Air Plan Approval; California; San 
Joaquin Valley Unified Air Pollution Control District; Open 
Burning,'' proposed rule signed December 16, 2021.
    \215\ EPA Region IX, ``Technical Support Document for EPA's 
Rulemaking for the California State Implementation Plan, San Joaquin 
Valley Unified Air Pollution Control District's Agricultural Burning 
Phase-Out Measure,'' December 2021.
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    For purposes of reviewing the Serious area plan for the 2012 annual 
PM2.5 NAAQS, the EPA has reviewed the District's method for 
calculating the emission reductions that this measure will achieve by 
January 1, 2025.

[[Page 74333]]

Specifically, the District calculated the annual average emissions of 
agricultural burning following full implementation of the phase-out 
(i.e., by January 1, 2025), considering the tonnages of waste and 
emission factors of each crop category (0.51 tpd NOX and 
0.67 tpd direct PM2.5).\216\ The District then subtracted 
these values (i.e., the additional reductions from the revised measure) 
from the annual average emissions in the baseline emissions inventory 
of the 2018 PM2.5 Plan for the 2025 attainment year (1.55 
tpd NOX and 2.21 tpd direct PM2.5).\217\ The 
resulting difference represents the annual average emission reductions 
to be achieved by the measure (1.04 tpd NOX and 1.54 tpd 
direct PM2.5).\218\
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    \216\ Agricultural Burning Phase-out Measure, Table 6.
    \217\ Id. at Table 4. See also, 2018 PM2.5 Plan, C-15 
(``Emissions Inventory'' table for open burning).
    \218\ Agricultural Burning Phase-out Measure, Table 6.
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    The EPA proposes that this is an appropriate calculation method to 
estimate the emission reductions from the Agricultural Burning Phase-
out Measure. It builds upon the baseline measure in the Plan for this 
source category (i.e., Rule 4103, amended April 15, 2010, and Table 9-
1, adopted May 20, 2010), applies appropriate emission factors, and 
identifies the difference between the Plan's baseline emissions and the 
emissions that would remain following full implementation of the 
measure. The January 1, 2025 deadline for final implementation is also 
consistent with the implementation deadline under 40 CFR 51.1011(b)(5) 
for control measures necessary for attainment by December 31, 2025. 
However, the EPA proposes to apply an 80% rule effectiveness rate, 
rather than the 100% rule effectiveness rate used in the District's 
calculation.\219\ After applying this effectiveness rate, the EPA 
proposes to credit this measure with emissions reductions of 0.83 tpd 
NOX and 1.23 tpd direct PM2.5 in 2025 (i.e., 
subtract these values from the District's tonnage commitments for 
2025). We provide further detail on this measure in sections III.B.1.a 
and IV.B.3.e of the EPA's 2012 Annual PM2.5 TSD.
---------------------------------------------------------------------------

    \219\ EPA Region IX, ``Technical Support Document for EPA's 
Rulemaking for the California State Implementation Plan, San Joaquin 
Valley Unified Air Pollution Control District's Agricultural Burning 
Phase-Out Measure,'' December 2021.
---------------------------------------------------------------------------

    The EPA anticipates finalizing action on the proposed rule on the 
Agricultural Burning Phase-out Measure prior to or concurrent with 
final action on the Serious area plan for the 2012 annual 
PM2.5 NAAQS for the SJV. Accordingly, Table 5 of this 
proposed rule summarizes the total NOX and direct 
PM2.5 emission reductions necessary to attain the 2012 
annual PM2.5 NAAQS in the SJV by December 31, 2025, the 
emission reductions attributed to baseline measures and new control 
strategy measures (including only measures approved or proposed for 
approval into the California SIP), and the emission reductions 
remaining as aggregate tonnage commitments. We estimate that 13.8% of 
the NOX reductions necessary for attainment and 8.0% of the 
direct PM2.5 reductions necessary for attainment remain as 
aggregate tonnage commitments. This remaining commitment is split 
between CARB and the District, as described further in this proposed 
rule. Notably, however, if the approval of the Agricultural Burning 
Phase-out Measure is finalized as proposed, the District will have met 
its direct PM2.5 emission reduction commitment of 1.3 tpd 
and, in fact, exceeded it by 0.13 tpd.\220\
---------------------------------------------------------------------------

    \220\ The direct PM2.5 emission reduction from Rule 
4901 (0.2 tpd) and the Agricultural Burning Phase-out Measure (1.23 
tpd) sum to 1.43 tpd, which exceeds the 1.3 tpd direct 
PM2.5 commitment by 0.13 tpd.

               Table 5--Reductions Needed for Attainment in 2025 and Aggregate Tonnage Commitments
----------------------------------------------------------------------------------------------------------------
                                                                                                   Direct PM2.5
                                                                                    NOX  (tpd)         (tpd)
 
----------------------------------------------------------------------------------------------------------------
A...............................  Total reductions needed from baseline and               207.38             6.4
                                   control strategy measures.
B...............................  Reductions from baseline measures.............           173.5             4.2
C...............................  Reductions from additional measures approved              4.46            0.46
                                   into the California SIP.
D...............................  Reductions from additional measures proposed              0.83            1.23
                                   for approval into the California SIP.
E...............................  Total reductions remaining as commitments (A-B-          28.59            0.51
                                   C-D).
F...............................  Percent of total reductions needed remaining             13.8%            8.0%
                                   as commitments (E/A).
----------------------------------------------------------------------------------------------------------------
Sources: 2018 PM2.5 Plan, Ch. 4, tables 4-3 and 4-7, and Appendix B, tables B-1 and B-2; EPA final rule signed
  December 16, 2021 (partial approval of the Agricultural Equipment Incentive Measure); and EPA proposed rule
  signed December 16, 2021 (proposing to approve the Agricultural Burning Phase-out Measure) and EPA Region IX,
  ``Technical Support Document for EPA's Rulemaking for the California State Implementation Plan, San Joaquin
  Valley Unified Air Pollution Control District's Agricultural Burning Phase-Out Measure,'' December 2021.

    Beyond the three measures that the EPA proposes to credit towards 
the aggregate tonnage commitments, CARB and the District have made 
substantial progress in developing and adopting additional measures, as 
described in the 2021 Progress Report. CARB has provided updated 
emission reduction estimates for 10 additional measures, including 9 
that have been adopted, as well as one substitute measure in 
development. The CARB measure with the largest updated emission 
reduction estimates is Heavy-Duty I/M. In the Valley State SIP 
Strategy, CARB originally estimated that Heavy-Duty I/M would achieve 
6.8 tpd NOX and <0.1 tpd direct PM2.5 in 2025 and 
described the regulatory concepts that would reflect the current (as of 
2018) ``advanced engine and exhaust control technologies, including on-
board diagnostics (OBD).'' \221\ Since that time, as described in the 
2021 Progress Report, California has developed additional provisions 
related to Heavy-Duty I/M that would achieve additional emission 
reductions.\222\
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    \221\ Valley State SIP Strategy, 19-20 and Table 8.
    \222\ 2021 Progress Report, 19. CARB notes that further detail 
on emission reduction calculations can be found in the CARB staff 
report on Heavy-Duty I/M, released October 15, 2021. See, CARB, 
``Staff Report: Initial Statement of Reasons, Public Hearing to 
Consider the Proposed Heavy-Duty Inspection and Maintenance 
Regulation,'' October 8, 2021, (``Heavy-Duty I/M ISOR'') and App. H 
(``Proposed Heavy-Duty Inspection and Maintenance Regulation, 
Standardized Regulatory Impact Assessment'').
---------------------------------------------------------------------------

    In particular, CARB states that California Senate Bill 210, signed 
into law in 2019, enhances the regulatory authority of this program by 
requiring that on-road heavy-duty vehicles comply with Heavy-Duty I/M 
in order to register annually with the California Department of Motor 
Vehicles. CARB also states that the periodic testing component of the 
program would be complemented by ``a new component, roadside emissions 
monitoring (remote sensing devices and/or CARB's Portable Emissions 
AcQuisition System, known as PEAQS) to detect high emitting

[[Page 74334]]

vehicles between periodic test cycles and require additional testing 
and repair to ensure emissions control components are operating 
properly.'' \223\ CARB estimates that Heavy-Duty I/M, as further 
developed since the Valley State SIP Strategy, will achieve 14.7 tpd 
NOX and 0.03 tpd direct PM2.5 in 2025 (i.e., 
roughly half the remaining aggregate commitment for NOX).
---------------------------------------------------------------------------

    \223\ 2021 Progress Report, 19.
---------------------------------------------------------------------------

    The EPA is not proposing to credit that amount of emission 
reductions towards the aggregate tonnage commitments at this time. The 
EPA would only take such action after Heavy-Duty I/M is approved by the 
California Office of Administrative Law, and the State submits the 
measure as a revision to the California SIP. Notwithstanding the fact 
that the EPA is not proposing to credit this program at this time, the 
EPA notes that CARB has developed this first-of-its-kind measure for 
on-road heavy-duty vehicles, documented its extensive regulatory and 
technical analyses in the measure's Initial Statement of Reasons and 
associated appendices,\224\ and explained how the provisions of the 
program have been expanded relative to those originally conceived as of 
2018.
---------------------------------------------------------------------------

    \224\ Heavy-Duty I/M ISOR and, for example, Heavy-Duty I/M ISOR, 
App. D (``Emissions Inventory Methods and Results, Proposed Heavy-
Duty Inspection and Maintenance Regulation'') and App. H (``Proposed 
Heavy-Duty Inspection and Maintenance Regulation, Standardized 
Regulatory Impact Assessment'').
---------------------------------------------------------------------------

    CARB has also been developing a substitute In-Use Locomotive 
Measure and plans to present the measure for board consideration in 
2022.\225\ The regulatory concepts in development for this measure 
include a ``Spending Account, Useful Life Limit, a 30-minute idling 
limit as well as reporting and recordkeeping requirements.'' \226\ CARB 
estimates that this measure will achieve reductions of 1.14 tpd 
NOX and 0.03 tpd direct PM2.5 in 2025.\227\ The 
EPA is aware of CARB's development of an In-Use Locomotive Measure and 
is not proposing to credit any amount of emission reductions towards 
the aggregate tonnage commitments.
---------------------------------------------------------------------------

    \225\ 2021 Progress Report, Table 2.
    \226\ Id. at 20-21. Additional information on CARB's regulatory 
concepts for the In-Use Locomotive Measure are available at: https://ww2.arb.ca.gov/our-work/programs/reducing-rail-emissions-california/locomotives-and-railyards-meetings-workshops.
    \227\ 2021 Progress Report, 21 and Table 2.
---------------------------------------------------------------------------

    The District has similarly provided updated emission reduction 
estimates for eight additional measures, including seven that have been 
adopted. The District measures with the largest updated emission 
reduction estimates include amendments to Rule 4702 (``Internal 
Combustion Engines'') (0.61 tpd NOX), the Residential Wood 
Burning Devices Incentive Projects measure (0.33 tpd direct 
PM2.5), and Rule 4354 (``Glass Melting Furnaces'') (0.5 tpd 
NOX and 0.04 tpd direct PM2.5), as well as 
amendments planned in 2022 to Rule 4550 (``Conservation Management 
Practices'') (0.32 tpd direct PM2.5).
    At this time, the EPA is not proposing to credit towards the 
aggregate tonnage commitments the updated emission reduction estimates 
from these additional CARB and District measures (beyond those we 
propose to credit elsewhere in this proposed rule). The EPA will review 
and take action on the CARB and District measures submitted to date 
(Innovative Clean Transit, Rule 4311, Rule 4306, Rule 4320, and Rule 
4702), as well as measure submissions in the future, in separate 
rulemakings, during which time the public will have an opportunity to 
review and provide comment. Although we are not proposing to credit 
reductions from these measures at this time, we have evaluated the 
updated emission reduction estimates to assess whether NOX 
and/or direct PM2.5 emission reduction commitments would be 
met or, conversely, how much emission reductions would remain of CARB 
and the District's aggregate tonnage commitments.
    Specifically, of the 12 additional measures for which CARB has 
provided updated emission reduction estimates, the emission reductions 
sum to 20.89 tpd NOX and 0.61 tpd direct 
PM2.5.\228\ Similarly, of the eight additional measures for 
which the District has provided updated emission reduction estimates, 
the emission reductions sum to 1.69 tpd NOX and 0.76 tpd 
direct PM2.5.\229\
---------------------------------------------------------------------------

    \228\ The EPA calculated these amounts by summing the updated 
emission reduction estimates for CARB's original set of control 
measures in the 2021 Progress Report, Table 2 (excluding estimates 
marked as ``<<0.01'' or ``N/A''), which sum to 25.35 tpd 
NOX and 0.87 tpd direct PM2.5, and subtracting 
the amount we propose to credit for the Carl Moyer and FARMER 
portions of the Agricultural Equipment Incentive Measure, which are 
4.46 tpd NOX and 0.26 tpd direct PM2.5. EPA's 
2012 Annual PM2.5 TSD, Table IV-A. Given the complex 
legal authorities involved in regulating locomotive emissions, we 
have conservatively excluded from our analysis the emission 
reduction estimates in the 2021 Progress Report for CARB's In-Use 
Locomotive Measure.
    \229\ The EPA calculated these amounts by summing the updated 
emission reduction estimates for the District's original set of 
control measures in the 2021 Progress Report, Table 3 (excluding 
estimates marked as ``- -''or ``TBD'', and excluding the 
Agricultural Burning Phase-out Measure, which was not part of the 
original set), which sum to 1.69 tpd NOX and 0.96 tpd 
direct PM2.5, and subtracting the amount we propose to 
credit for Rule 4901, which is 0.2 tpd direct PM2.5. 
EPA's 2012 Annual PM2.5 TSD, Table IV-B.
---------------------------------------------------------------------------

    The combined emission reductions from these additional measures are 
22.58 tpd NOX and 1.37 tpd direct PM2.5. 
Subtracting these amounts from the remaining aggregate tonnage 
commitments of 28.59 tpd NOX and 0.51 tpd direct 
PM2.5 (i.e., Row E of Table 5 of this proposed rule) would 
result in necessary, remaining reductions of 6.01 tpd NOX to 
achieve the modeled attainment reductions and an excess 0.86 tpd direct 
PM2.5.\230\ Notably, the District would have exceeded its 
aggregate tonnage commitments by 0.64 tpd NOX and 0.89 tpd 
direct PM2.5.\231\ CARB would have remaining emission 
reductions of 6.65 tpd NOX and 0.03 tpd direct 
PM2.5.\232\
---------------------------------------------------------------------------

    \230\ CARB and the District estimate that, considering the 
updated emission reduction estimates for the original and substitute 
measures, the remaining aggregate tonnage commitment would be 4.65 
tpd NOX and an excess of 1.2 tpd direct PM2.5. 
2021 Progress Report, 30. The difference between those sums and the 
EPA's sums is 0.22 tpd NOX and 0.31 tpd direct 
PM2.5, which reflects the difference between the SIP 
credit that we propose for the Agricultural Burning Phase-out 
Measure (0.83 tpd NOX, and 1.23 tpd direct 
PM2.5) and the State's claimed reduction (1.04 tpd 
NOX and 1.54 tpd direct PM2.5), and the 
emission reduction estimate for the In-Use Locomotive Measures (1.14 
tpd NOX and 0.03 tpd direct PM2.5).
    \231\ The emission reduction from Rule 4901 (0.2 tpd direct 
PM2.5), the Agricultural Burning Phase-out Measure (0.83 
tpd NOX and 1.23 tpd direct PM2.5), and 
additional measures sum to 2.52 tpd NOX and 2.19 tpd 
direct PM2.5, which would exceed the District's 1.88 tpd 
NOX and 1.3 tpd direct PM2.5 commitments by 
0.64 tpd NOX and 0.89 tpd direct PM2.5.
    \232\ The emission reduction from the Carl Moyer and FARMER 
portions of the Agricultural Equipment Incentive Measure and 
additional measures sum to 25.35 tpd NOX and 0.87 tpd 
direct PM2.5, which would leave 6.65 tpd NOX 
and 0.03 tpd direct PM2.5 relative to CARB's commitments 
of 32 tpd NOX and 0.9 tpd direct PM2.5.
---------------------------------------------------------------------------

    With respect to CARB's remaining emission reductions for 
NOX, as well as any future decrease in any updated emission 
reduction estimates in the 2021 Progress Report and/or any smaller 
amount of credit that the EPA may approve for those measures, we have 
considered the role of additional measures for which CARB and the 
District have not yet quantified an updated emission reduction 
estimate.
    CARB identifies four measures of its original control measure 
commitments with updated emission reduction estimates of ``<<0.1'' or 
``N/A,'' each of which is overdue. First, the Zero-Emission Airport 
Ground Support Equipment measure, for which the updated year for board 
consideration is not specified, had original emission reduction 
estimates that were quite small at <0.1 tpd NOX and <0.1 tpd 
direct PM2.5. Second, the Low-emission

[[Page 74335]]

Diesel Fuel Requirement, anticipated for 2022 board consideration, had 
original emission reduction estimates of 1 tpd NOX and 0.1 
tpd direct PM2.5. Of these two regulatory measures, we 
assume the latter may result in SIP creditable emission reductions for 
a portion of the 1 tpd NOX, given the one-year delay in 
bringing the measure to the board and corresponding likelihood of one-
year delay in implementation.
    Third and fourth, the Accelerated Turnover of Trucks and Buses 
Incentive Projects measure and the Accelerated Turnover of Off-Road 
Equipment Incentive Projects measure had original emission reduction 
estimates of 8 tpd NOX and 1.5 tpd NOX, 
respectively. As discussed in section IV.F.3.c of this proposed rule, 
CARB states that it continues to assess the emission reductions from 
these two incentive-based measures that could be applied towards the 
aggregate tonnage commitments.\233\ We assume that these measures may 
result in SIP-creditable emission reductions for a portion of the 
combined 9.5 tpd NOX.
---------------------------------------------------------------------------

    \233\ 2021 Progress Report, 24.
---------------------------------------------------------------------------

    In addition, CARB has identified further measures that were not 
included in the original control measure commitments that may provide 
emission reductions toward CARB's aggregate tonnage commitments.\234\ 
These measures include Cargo Handling Equipment Registration, 
Construction and Mining Equipment Measure, and Co-Benefits from the 
Climate Program.
---------------------------------------------------------------------------

    \234\ CARB, ``SJV PM2.5 SIP Measure Tracking,'' 
September 2021, 3. Available at: https://ww2.arb.ca.gov/resources/documents/2018-san-joaquin-valley-pm25-plan.
---------------------------------------------------------------------------

    Similarly, the District identifies three measures of its original 
control measure commitments with updated emission reduction estimates 
of ``- -'' or ``TBD,'' each of which is overdue, which we outline as 
follows. First and second, the regulatory measure and incentive-based 
measure for commercial charbroiling had original emission reduction 
estimates of 0.53 tpd direct PM2.5. The District continues 
to work on this source category, including the evaluation of 
``potential amendments to Rule 4692 in the near future.'' \235\ 
However, we assume that such amendments would not produce 
NOX emission reductions.
---------------------------------------------------------------------------

    \235\ 2021 Progress Report, 9.
---------------------------------------------------------------------------

    Third, the District originally estimated emission reductions of 
1.07 tpd NOX from the combination of regulatory and 
incentive-based measures for stationary internal combustion engines, 
especially with respect to agricultural engines.\236\ Pending the EPA's 
evaluation of the 2021 amendment to Rule 4702, which claims 0.61 
NOX emission reductions in 2025, this would leave 0.46 tpd 
NOX to be achieved by the Agricultural Operation Internal 
Combustion Engines Incentive Projects measure. We assume that this 
measure may result in SIP-creditable emission reductions for a portion 
of the combined 1.07 tpd NOX.
---------------------------------------------------------------------------

    \236\ 2018 PM2.5 Plan, Ch. 4, Table 4-3 and App. E, 
Table E-3.
---------------------------------------------------------------------------

    The EPA does not have information at this time sufficient to 
quantify a precise amount of NOX reductions that would 
result from the Low-emission Diesel Fuel Requirement and incentive-
based measures for heavy-duty trucks, off-road equipment, and 
stationary agricultural internal combustion engines, nor the three 
additional measures identified in CARB's ``SJV PM2.5 SIP 
Measure Tracking,'' September 2021. Notwithstanding this uncertainty, 
CARB and the District state that they are ``committed to fulfilling 
their respective aggregate commitments from the 2018 PM2.5 
Plan and continue to progress in developing their respective measures 
within the Plan'' and that upcoming regulations could achieve more 
reductions than originally anticipated.\237\
---------------------------------------------------------------------------

    \237\ 2021 Progress Report, 2 and 32.
---------------------------------------------------------------------------

    In addition, CARB and the District assert that the District has 
achieved more direct PM2.5 emission reductions than they 
committed to in their aggregate tonnage commitment.\238\ Accordingly, 
they provided additional emissions analysis to assess how excess direct 
PM2.5 emission reductions could be converted to equivalent 
NOX emission reductions using an inter-pollutant trading 
ratio rooted in the sensitivity analyses of the 2018 PM2.5 
Plan.\239\ To be clear, CARB and the District have not formally 
requested that the EPA apply such inter-pollutant trading for purposes 
of fulfilling the aggregate tonnage commitments through an equivalent 
amount of emission reductions. Consistent with past EPA action on 
PM2.5 planning SIP submissions for the SJV,\240\ where the 
State submits a SIP revision that would substitute reductions in one 
pollutant to achieve a tonnage commitment concerning a different 
pollutant (e.g., substituting excess 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 any such SIP revision.
---------------------------------------------------------------------------

    \238\ Id. at 32.
    \239\ Id. at Table 4 and 33-37.
    \240\ For example, the EPA has approved an inter-pollutant 
trading mechanism for use in transportation conformity analyses for 
the 2006 24-hour PM2.5 NAAQS. 85 FR 44192, 44204. In that 
same final rule, the EPA approved the State's demonstration that it 
had fulfilled prior aggregate tonnage commitments, in part, by using 
an inter-pollutant trading approach that the EPA found adequate. 85 
FR 44192, 44205; see also proposed rule at 85 FR 17382, 17406-17407 
and associated EPA's General Evaluation TSD, Table III-C and section 
IV.
---------------------------------------------------------------------------

    Thus, at this time, we are not proposing to approve any particular 
inter-pollutant trading approach for purposes of meeting the aggregate 
tonnage commitments, nor applying any excess reductions of one 
pollutant towards fulfilling a portion of committed reductions of the 
other pollutant. Nevertheless, we note that because, as proposed, the 
District's direct PM2.5 reductions have exceeded their 
aggregate tonnage commitment, these excess reductions add a degree of 
conservativeness to the combined attainment demonstration and control 
plan. In light of the possibility of future interpollutant trading, we 
have qualitatively evaluated the State's inter-pollutant trading 
analysis as part of our assessment of the State's capability to fulfill 
CARB and the District's aggregate tonnage commitments, as discussed 
further in section IV.B.5 of the EPA's 2012 Annual PM2.5 
TSD.
(e) 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.\241\ 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

[[Page 74336]]

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.
---------------------------------------------------------------------------

    \241\ 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: (a) Does the commitment address a limited portion of the 
CAA requirement; (b) is the state capable of fulfilling its commitment; 
and (c) is the commitment for a reasonable and appropriate period of 
time.\242\
---------------------------------------------------------------------------

    \242\ 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 SJV, based on the same three factor test. Committee for 
a Better Arvin v. EPA, 786 F.3d 1169 (9th Cir. 2015).
---------------------------------------------------------------------------

    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 shown in Table 5 of this 
proposed rule, the majority of the emissions reductions needed to 
demonstrate attainment and RFP in the SJV 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 SJV 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 65.4% and 10.2%, 
respectively, from 2013 base year levels in order to attain the 2012 
annual PM2.5 NAAQS by the end of 2025 in the SJV.
    As part of their respective control measure commitments in the SJV 
PM2.5 Plan, CARB and the District identified potential 
control measures that they expected to achieve the additional emissions 
reductions needed for attainment. The timeline needed to develop, 
adopt, and implement these measures extended beyond the year of Plan 
adoption, with most measures originally scheduled for board 
consideration in 2019, 2020, and 2021. Both CARB and the District have 
made substantial progress in adopting the rules and measures listed in 
their respective control measure commitments, as well as one important 
substitute measure, but have not yet completely fulfilled the control 
measure commitments. Given these circumstances, we conclude that CARB 
and District's 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.
(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 shown in Table 5 of this proposed rule, most of the total 
emission reductions needed to attain the 2012 annual PM2.5 
NAAQS in the SJV by the end of 2025 will be achieved through 
implementation of baseline measures and additional measures for which 
the EPA has finalized or proposed approval, leaving 13.8% (28.59 tpd) 
of the necessary NOX reductions and 8.0% (0.51 tpd) of the 
necessary direct PM2.5 reductions as aggregate tonnage 
commitments.
    Given the nature of the PM2.5 challenge in the SJV, 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 District to seek 
additional time to develop and adopt the last increment of emission 
reductions necessary for attainment by 2025.
    Therefore, we conclude that the 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 2012 annual PM2.5 NAAQS by December 31, 
2025.
(2) The State Is Capable of Fulfilling Its Commitment
    For the second factor, we consider whether the State and District 
are capable of fulfilling their commitments. As discussed in section 
IV.F.3.c of this proposed rule and shown in tables IV.A and IV.B of the 
EPA's 2012 Annual PM2.5 TSD, the EPA notes that CARB and the 
District have made substantial progress in developing and adopting the 
regulatory measures listed in their respective control measure 
commitments. Specifically, CARB and the District have adopted 18 
measures of the 27 control measure commitments in the SJV 
PM2.5 Plan. CARB has adopted 10 measures (including one 
incentive-based measure) and begun the public process on 3 of the 
remaining 5 measures. The adopted measures include, for example, Heavy-
Duty I/M, the California Heavy-Duty Low-NOX Engine Standard, 
the SORE regulation, and the Agricultural Equipment Incentive Measure.
    The District has adopted eight measures (including one incentive-
based measure) and begun the public process on two of the remaining 
four measures. The adopted measures include, for example, amendments to 
Rule 4311 (``Flares''), Rule 4702 (``Internal Combustion Engines''), 
and Rule 4901 (``Woodburning Fireplaces and Wood Burning Heaters'') 
(Hot-spot strategy), and the Residential Wood Burning Devices Incentive 
Projects measure.
    As discussed in section IV.3.d of this proposed rule, the remaining 
aggregate tonnage commitments sum to 28.59 tpd NOX and 0.51 
tpd direct PM2.5. We also note that, pending final approval 
of the Agricultural Burning Phase-out Measure, that the District will 
have met its 1.3 tpd direct PM2.5 commitment and, in fact, 
exceeded it by 0.13 tpd. Based on our review of the State's 2021 
Progress Report, CARB has adopted 10 additional measures and advanced 
their development and analysis of two additional measures of the Plan's 
original control measure commitments (one slated for board 
consideration in 2022 and one as early as 2022), and also developed a 
substitute measure (slated for board consideration in 2022). Similarly, 
beyond the two adopted measures (Rule 4901 and the Agricultural Burning 
Phase-out Measure) that the EPA proposes to credit towards the 
aggregate tonnage commitments, the District has adopted seven 
additional measures.
    The updated emission reduction estimates for this series of 
additional CARB and District measures sum to

[[Page 74337]]

22.58 tpd NOX and 1.37 tpd direct PM2.5. Relative 
to the original emission reduction estimates in the SJV 
PM2.5 Plan, these estimated emission reductions are more 
robust in that they reflect adopted measures and associated technical 
analyses, as well as further measure development and estimation. 
Pending the additional steps that precede submission of the measures to 
the EPA and the EPA's future evaluation of and rulemaking on each 
measure, subtracting these amounts from the remaining aggregate tonnage 
commitments would result in necessary, remaining reductions of 6.01 tpd 
NOX to achieve the modeled attainment reductions and an 
excess 0.86 tpd direct PM2.5. The District would have 
exceeded its aggregate tonnage commitments by 0.64 tpd NOX 
and 0.89 tpd direct PM2.5. CARB would have remaining 
emission reductions of 6.65 tpd NOX and 0.03 tpd direct 
PM2.5.
    As further discussed in section IV.F.3.d of this proposed rule, we 
have considered the role of additional measures for which CARB and the 
District have not yet quantified an updated emission reduction 
estimate, which includes several CARB and District measures that may 
yet achieve sufficient emission reductions to fulfill the remaining 
aggregate tonnage commitment for NOX. CARB and the District 
state that they are ``committed to fulfilling their respective 
aggregate commitments from the 2018 PM2.5 Plan and continue 
to progress in developing their respective measures within the Plan'' 
and that upcoming regulations could achieve more reductions than 
originally anticipated.\243\
---------------------------------------------------------------------------

    \243\ 2021 Progress Report, 2 and 32.
---------------------------------------------------------------------------

    Beyond the measures discussed above, both CARB and the District 
have well-established incentive grant programs to reduce emissions from 
mobile, stationary, and area sources in the SJV. Funding for the 
State's incentive programs in the SJV comes from various sources 
including the Carl Moyer Program, Proposition 1B Goods Movement 
Emission Reduction Program, Greenhouse Gas Reduction Fund, and the 
Funding Agricultural Replacement Measures for Emission Reductions 
(FARMER) program.\244\ Funding for the District's incentive programs 
comes from a combination of federal, State, and local funding 
mechanisms, including the Diesel Emission Reduction Act (DERA) and 
Target Airshed Grant programs, the Carl Moyer program, and fees 
assessed in the SJV by the California Department of Motor Vehicles and 
by the District through programs for Indirect Source Review, Voluntary 
Emission Reduction Agreements, and large boilers, steam generators, and 
process heaters.\245\
---------------------------------------------------------------------------

    \244\ 2018 PM2.5 Plan, App. E, E-6.
    \245\ Id.
---------------------------------------------------------------------------

    Collectively, these incentive funds have been applied to a wide 
range of emission sources, including heavy-duty trucks, light-duty 
vehicles, mobile agricultural equipment, locomotives, school buses, 
alternative fuel infrastructure, community-based programs, agricultural 
irrigation pumps, residential wood combustion devices, and commercial 
charbroilers.\246\ The Plan identifies the total funding need for 
expeditious attainment as $5 billion, including $3.3 billion for heavy-
duty trucks and buses and $1.4 billion for mobile agricultural 
equipment.\247\
---------------------------------------------------------------------------

    \246\ Id. at App. E, E-8 to E-21.
    \247\ Id. at App. E, Table E-4 (``Incentive Funding Needed for 
Expeditious Attainment''). The CARB Staff Report describes the 
status of current incentive funding and CARB's expectations 
concerning future incentive funding out to 2024 for the SJV. CARB 
Staff Report, section F (``Status of Incentive Funding''), 24-27.
---------------------------------------------------------------------------

    However, CARB staff explained that, in light of the progress to-
date on committed-to regulatory measures and these two substitute 
measures, fewer incentive-based emission reductions may ultimately be 
needed to demonstrate attainment of the 2012 annual PM2.5 
NAAQS.\248\ For heavy-duty trucks and off-road equipment, CARB notes 
that incentives have paid for the turn-over of such equipment, but that 
many of the projects do not have contract lives that span the 
attainment year (2025) and therefore would not be creditable for the 
purposes of the 2012 annual PM2.5 NAAQS. Conversely, CARB 
states that it will achieve 5.1 tpd NOX and 0.3 tpd direct 
PM2.5 emission reductions in 2025 via the Agricultural 
Equipment Incentive Measure, which relies on funding from the Carl 
Moyer, FARMER, and NRCS programs. For the two State-funded programs, 
CARB states that Carl Moyer funding is expected to increase in future 
years, following enactment of California Assembly Bill 1274,\249\ and 
that the recent (fiscal year 2021-2022) state budget provides $212.6 
million for FARMER program statewide \250\--the largest annual amount 
to date. The SJV portion of such FARMER funding has historically been 
80%.\251\ Given our proposal to credit the Agricultural Equipment 
Inventive Measure for significant emission reductions towards CARB's 
aggregate tonnage commitments in 2025, the renewed, large investment in 
the fiscal year 2021-2022 FARMER program, and potential for increases 
in funding for the Carl Moyer program, the EPA anticipates that CARB 
will be able to develop an additional agricultural equipment incentive 
measure that produces SIP-creditable emission reductions.
---------------------------------------------------------------------------

    \248\ CARB, ``Valley PM2.5 Implementation Update and 
SIP Amendment,'' September 23, 2021, slides 22-25. Slide 25 
illustrates a large decrease in the expected funding need from 
approximately $5 billion over 2018-2025 to approximately $1 billion 
over 2021-2025.
    \249\ 2021 Progress Report, 22.
    \250\ Id. at 23.
    \251\ In the inaugural year of the FARMER program, fiscal year 
2017-2018, of the $135 million funding allocated state-wide, $108 
million (80%) was directed to the SJV. Subsequent allocations to the 
SJV were $104.3 million (fiscal year 2018-2019) and $43.84 million 
(fiscal year 2019-2020). CARB, ``Funding Agricultural Replacement 
Measures for Emission Reductions (FARMER) Program, San Joaquin 
Valley APCD,'' as reported through September 30, 2020.
---------------------------------------------------------------------------

    More broadly, whether for regulatory measures or incentive-based 
measures, we note also that CARB and the District 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, where CARB or the District intend 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.
    Given CARB and the District's progress in adopting 18 measures to 
date, their substantial progress toward achieving the aggregate tonnage 
commitments, including the District having met and exceeded its direct 
PM2.5 commitment, their ongoing efforts to develop 
additional measures, and their stated intent to continue to fulfill 
their respective commitments, we propose that CARB and the District are 
capable of fulfilling the remaining increment of NOX 
emission reductions necessary to attain the 2012 annual 
PM2.5 NAAQS in the SJV by December 31, 2025.
(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. As discussed in section II.B 
of this proposed rule, on March 23, 2017, CARB adopted the 2016 State 
Strategy and directed staff to return to the Board with a commitment to 
achieve additional emission reductions from

[[Page 74338]]

mobile sources in the SJV.\252\ CARB responded by developing the Valley 
State SIP Strategy, which includes additional State commitments to 
achieve accelerated emission reductions for purposes of attaining the 
PM2.5 NAAQS in the SJV.
---------------------------------------------------------------------------

    \252\ CARB Resolution 17-7, page 7.
---------------------------------------------------------------------------

    In the Valley State SIP Strategy, CARB recognized that the earlier 
attainment dates for the 1997, 2006, and 2012 PM2.5 NAAQS in 
the SJV, compared to ozone attainment dates in the SJV and elsewhere in 
the State, required accelerating the pace of NOX 
reductions.\253\ Thus, in the Valley State SIP Strategy CARB identified 
and committed to achieve emission reductions of 32 tpd of 
NOX and 0.9 tpd of direct PM2.5 by 2024,\254\ 
significantly greater amounts than those CARB had committed to in the 
2016 State Strategy (6 tpd of NOX and 0.1 tpd of direct 
PM2.5 by 2025).\255\
---------------------------------------------------------------------------

    \253\ Valley State SIP Strategy, 2-3 and 6.
    \254\ CARB Resolution 18-49, page 5.
    \255\ CARB Resolution 17-7, paragraph 7.
---------------------------------------------------------------------------

    The SJV PM2.5 Plan includes specific rule development, 
adoption, and implementation schedules designed to meet CARB and the 
District's commitments to reduce emissions to the levels needed to 
attain the 2012 annual PM2.5 NAAQS in the SJV by 2025. For 
example, the aggregate commitments in the SJV PM2.5 Plan 
include commitments by both CARB and the District to begin the public 
process on each of their respective control measure commitments by 
specific dates ranging from 2015 to 2021. The commitments also identify 
action and implementation dates ranging from 2018 to 2024 for a number 
of CARB and District control measures.\256\
---------------------------------------------------------------------------

    \256\ 2018 PM2.5 Plan, Ch. 4, tables 4-4, 4-5, and 4-
8.
---------------------------------------------------------------------------

    As discussed in section IV.F.3.c of this proposed rule, consistent 
with that schedule, CARB and the District have adopted 18 measures of 
the 27 control measure commitments and timely began public process on 
the 4 remaining regulatory measures. While CARB and the District are 
overdue in proposing the four remaining regulatory measures and the 
remaining four incentive measures to their respective boards, they have 
indicated that they will propose at least two of the remaining 
regulatory measures to their respective boards in 2022, including the 
Low-emission Diesel Fuel Requirement and Rule 4550 (``Conservation 
Management Practices''), and one more regulatory measure, the Zero-
Emission Off-Road Forklift Regulation Phase 1 measure, as early as 
2022.
    We consider that these schedules provide a reasonable and 
appropriate amount of time for CARB and the District to achieve the 
remaining emission reductions necessary to attain the 2012 annual 
PM2.5 NAAQS in the SJV by December 31, 2025. We therefore 
propose to conclude that the third factor is satisfied.

G. Reasonable Further Progress and Quantitative Milestones

1. Requirements for Reasonable Further Progress and Quantitative 
Milestones
    Section 172(c)(2) of the Act 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 contain quantitative 
milestones for purposes of measuring RFP, as defined in CAA section 
171(1), every three years until the EPA redesignates the area to 
attainment. Section 171(1) of the Act defines RFP as the annual 
incremental reductions in emissions of the relevant air pollutant as 
are required by part D, title I of the Act, or as may reasonably be 
required by the Administrator for the purpose of ensuring attainment of 
the NAAQS by the applicable attainment 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 particulate matter NAAQS, RFP has historically 
been met by showing annual incremental emissions reductions sufficient 
to maintain ``generally linear progress'' toward attainment by the 
applicable deadline.\257\ As discussed in EPA guidance in the General 
Preamble Addendum, requiring generally linear progress in reductions of 
direct PM and relevant PM precursors in an attainment plan may be 
appropriate in situations where:
---------------------------------------------------------------------------

    \257\ General Preamble Addendum, 42015.
---------------------------------------------------------------------------

     The pollutant is emitted by a large number and range of 
sources,
     the relationship between any individual source or source 
category and overall air quality is not well known,
     a chemical transformation is involved (e.g., secondary 
particulate significantly contributes to PM levels over the standard), 
and/or
     the emission reductions necessary to attain the 
PM2.5 standards are inventory-wide.\258\
---------------------------------------------------------------------------

    \258\ Id.
---------------------------------------------------------------------------

    The EPA believes that the facts and circumstances of each specific 
area will be relevant to whether the emissions reductions meet the 
agency's expectations for generally linear progress.\259\
---------------------------------------------------------------------------

    \259\ 80 FR 15340, 15386.
---------------------------------------------------------------------------

    The General Preamble Addendum also indicates that requiring 
generally linear progress may be less appropriate in other situations, 
such as:
     Where there are a limited number of sources of direct PM 
or a relevant precursor,
     where the relationships between individual sources and air 
quality are relatively well defined, and/or
     where the emission control systems utilized (e.g., at 
major point sources) will result in swift and dramatic emission 
reductions.
    In nonattainment areas characterized by any of these latter 
conditions, the EPA has recommended that RFP may be met by stepwise 
progress as controls are implemented and achieve significant reductions 
soon thereafter. For example, if an area's nonattainment problem can be 
attributed to a few major stationary sources, EPA guidance recommends 
that states may meet RFP by ``adherence to an ambitious compliance 
schedule'' that is likely to yield significant reductions of direct PM 
or a PM precursor on a periodic basis, rather than on a generally 
linear basis.\260\ The EPA believes that the facts and circumstances of 
each specific area will be relevant to whether the emissions reductions 
meet the agency's expectations for stepwise progress.
---------------------------------------------------------------------------

    \260\ Id.
---------------------------------------------------------------------------

    Plans for PM nonattainment areas should include detailed schedules 
for compliance with emission control measures in the area and provide 
corresponding annual emission reductions to be achieved by each 
milestone in the schedule.\261\ 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 PM earlier to provide greater public health benefits.\262\
---------------------------------------------------------------------------

    \261\ General Preamble Addendum at 42016.
    \262\ Id.
---------------------------------------------------------------------------

    In addition to the EPA's longstanding guidance on the RFP 
requirements for

[[Page 74339]]

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 provided 
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.\263\
---------------------------------------------------------------------------

    \263\ 40 CFR 51.1012(a).
---------------------------------------------------------------------------

    A state intending to meet the RFP requirement on a stepwise basis 
must provide an appropriate justification for the selected 
implementation schedule.\264\ As the EPA explained in the preamble to 
the PM2.5 SIP Requirements Rule, a state that relies on a 
stepwise approach to meeting RFP should include ``a clear rationale and 
supporting information to explain why generally linear progress is not 
appropriate (e.g., due to the nature of the nonattainment problem, the 
types of sources contributing to PM2.5 levels in the area 
and the implementation schedule for control requirements at such 
sources).'' \265\ Additionally, states should estimate the RFP 
projected emissions for each quantitative milestone year by sector on a 
pollutant-by-pollutant basis.\266\
---------------------------------------------------------------------------

    \264\ 40 CFR 51.1012(a)(4).
    \265\ 81 FR 58010, 58057.
    \266\ Id. at 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 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., the calculations and any assumptions made concerning 
emission reductions to date.\267\
---------------------------------------------------------------------------

    \267\ 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.\268\ 
Consistent with this longstanding interpretation of the Act, the 
PM2.5 SIP Requirements Rule requires that each plan for a 
Serious PM2.5 nonattainment area that demonstrates 
attainment by the end of the 10th calendar year following the date of 
designation contain quantitative milestones to be achieved no later 
than milestone dates 7.5 years and 10.5 years from the date of 
designation of the area.\269\ The 2018 PM2.5 Plan includes a 
demonstration of attainment by the end of the 10th calendar year 
following designations (i.e., December 31, 2025). Because the EPA 
designated the SJV nonattainment for the 2012 annual PM2.5 
NAAQS effective April 15, 2015,\270\ the applicable quantitative 
milestone dates for purposes of the submitted Serious area plan for 
this NAAQS in the SJV are October 15, 2022, and October 15, 2025.
---------------------------------------------------------------------------

    \268\ General Preamble, 13539 and General Preamble Addendum, 
42016.
    \269\ 40 CFR 51.1013(a)(2)(i).
    \270\ 80 FR 2206.
---------------------------------------------------------------------------

    Quantitative milestones must provide for objective evaluation of 
reasonable further progress 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.\271\
---------------------------------------------------------------------------

    \271\ 81 FR 58010, 58064 and 58092.
---------------------------------------------------------------------------

2. Summary of State's Submission
    Appendix H (``RFP, Quantitative Milestones, and Contingency'') of 
the 2018 PM2.5 Plan contains the State's RFP demonstration 
and quantitative milestones for the 2012 annual PM2.5 NAAQS. 
Following the identification of a transcription error in the RFP tables 
of Appendix H, the State submitted a revised version of Appendix H that 
corrects the transcription error and provides additional information on 
the RFP demonstration.\272\ Given the State's conclusions that ammonia, 
SOX, and VOC emissions do not contribute significantly to 
PM2.5 levels that exceed the 2012 annual PM2.5 
NAAQS in the SJV, 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.\273\ Similarly, the State 
developed quantitative milestones based upon the Plan's control 
strategy measures that achieve emission reductions of direct 
PM2.5 and NOX.\274\ For the 2012 annual 
PM2.5 NAAQS, the RFP demonstration in the Plan follows a 
stepwise approach due to the time required for CARB and the District 
``to amend rules, develop programs, and implement the emission 
reduction measures.'' \275\ The revised Appendix H provides clarifying 
information on the RFP demonstration, including additional information 
to justify the Plan's stepwise approach to demonstrating RFP. This 
clarifying information did not affect the Plan's quantitative 
milestones. We describe the RFP demonstration and quantitative 
milestones in the SJV PM2.5 Plan in greater detail below.
---------------------------------------------------------------------------

    \272\ Appendix H to 2018 PM2.5 Plan, submitted 
February 11, 2020, via the EPA State Planning Electronic 
Collaboration System. This revised version of Appendix H replaces 
the version submitted with the 2018 PM2.5 Plan on May 10, 
2019. All references to Appendix H in this proposed rule are to the 
revised version of Appendix H submitted February 11, 2020.
    \273\ 2018 PM2.5 Plan, App. H, H-1.
    \274\ Id. at App. H, H-23 to H-24 (for CARB milestones) and H-20 
to H-22 (for District milestones).
    \275\ Id. at App. H, H-4.
---------------------------------------------------------------------------

(a) Reasonable Further Progress
    The State addressed the RFP and quantitative milestone requirements 
in Appendix H to the 2018 PM2.5 Plan submitted in February 
2020. The State estimates that emissions of direct PM2.5 and 
NOX will generally decline from the 2013 base year to the 
projected 2025 attainment 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 SJV. Table H-2 in Appendix H 
contains an anticipated implementation schedule for District

[[Page 74340]]

regulatory control measures and Table 4-8 in Chapter 4 of the 2018 
PM2.5 Plan contains an anticipated implementation schedule 
for CARB control measures in the SJV. Table H-5 in Appendix H 
(reproduced in Table 6 of this proposed rule) contains projected 
emissions for each quantitative milestone year and the attainment year. 
These emission levels reflect both baseline emissions projections and 
commitments to achieve additional emission reductions through 
implementation of new control measures by 2025.\276\
---------------------------------------------------------------------------

    \276\ In App. H, see tables H-3 (emission projections based on 
baseline measures) and H-4 (reductions from control measure 
commitments). The SJV PM2.5 Plan includes commitments for 
reductions from new control measures by 2024 and 2025.

   Table 6--PM2.5 Projected Emissions Inventory for Base and Milestone Years, Including Baseline Measures and
                                         Emission Reduction Commitments
                                              [Annual average, tpd]
----------------------------------------------------------------------------------------------------------------
                                                       2013          2019 \a\          2022            2025
----------------------------------------------------------------------------------------------------------------
                                                                                                   Quantitative
                                                                   Quantitative    Quantitative    milestone and
                    Pollutant                      Baseline year     milestone       milestone      attainment
                                                                                                       year
----------------------------------------------------------------------------------------------------------------
PM2.5...........................................            62.5            59.2            58.4            56.1
NOX.............................................           317.2           214.5           179.8           109.8
----------------------------------------------------------------------------------------------------------------
Source: 2018 PM2.5 Plan, Appendix H, Table H-5.
\a\ 2019 is a quantitative milestone year in the SJV for the 2012 annual PM2.5 NAAQS for purposes of CAA
  requirements for Moderate PM2.5 nonattainment areas.

    Table H-6 and Table H-7 of Appendix H (reproduced in Table 7 of 
this proposed rule) identify the reductions needed for attainment of 
the 2012 annual PM2.5 NAAQS by 2025, and the SJV's projected 
progress toward attainment in each milestone year.

             Table 7--Emission Reductions Needed for Attainment and Achieved in Each Milestone Year
                                                [Annual average]
----------------------------------------------------------------------------------------------------------------
                                                                   Percent reductions achieved in milestone year
                                                    Reductions   -----------------------------------------------
                                                    needed for         2019            2022            2025
                    Pollutant                       attainment   -----------------------------------------------
                                                    (from 2013     Quantitative    Quantitative     Attainment
                                                     baseline)       milestone       milestone         year
----------------------------------------------------------------------------------------------------------------
PM2.5...........................................         6.4 tpd            51.6            64.1             100
NOX.............................................       207.4 tpd            49.5            66.2             100
----------------------------------------------------------------------------------------------------------------
Source: 2018 PM2.5 Plan, Appendix H, tables H-6 and H-7.

    Based on the data in tables 6 and 7 of this proposed rule, CARB and 
the District set RFP targets for the attainment year and quantitative 
milestone years as shown in Table H-11 of Appendix H (reproduced in 
Table 8 of this proposed rule). The targets are consistent with a 
stepwise approach to demonstrating RFP. The emission projections show 
steady reductions over time. The reductions between the 2013 base year 
and the 2019 milestone year (51.6% of the direct PM2.5 
reductions and 49.5% of the NOX reductions needed for 
attainment), which we evaluated in the context of the Moderate area 
requirements for RFP and quantitative milestones, are consistent with a 
generally linear approach to demonstrating RFP. Emissions further 
decrease by the 2022 milestone year but fall short of the rate of 
reductions that would show generally linear progress toward 
attainment.\277\ The Plan relies on a more substantial direct 
PM2.5 and NOX emission reduction by 2025 due, in 
large part, to CARB and the District's commitments to achieve 
additional PM2.5 emission reductions from new measures by 
2025.
---------------------------------------------------------------------------

    \277\ To show generally linear progress, emissions would need to 
decrease by approximately 75% from 2013 to 2022. The projected 
decrease for this span of years is 64.1% for direct PM2.5 
and 66.2% for NOX.
---------------------------------------------------------------------------

    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 2025 attainment 
year. Based on these analyses, CARB and the District assert that the 
adopted control strategy and additional commitments for reductions from 
new control programs by 2025 are adequate to meet the RFP requirement 
for the 2012 annual PM2.5 NAAQS.

                      Table 8--Stepwise RFP Target Emission Levels and Projected Emission Levels for Milestone and Attainment Years
                                                                  [Annual average, tpd]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                        Pollutant                                      2019                            2022                            2025
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                              Target         Projected        Target         Projected        Target         Projected
--------------------------------------------------------------------------------------------------------------------------------------------------------
PM2.5...................................................            59.2            59.2            58.4            58.4            56.1            56.1

[[Page 74341]]

 
NOX.....................................................           214.5           214.5           179.8           179.8           109.8           109.8
--------------------------------------------------------------------------------------------------------------------------------------------------------
Source: 2018 PM2.5 Plan, Appendix H, Table H-11.

    CARB and the District's control strategy in the 2018 
PM2.5 Plan for attaining the 2012 annual PM2.5 
NAAQS relies on ongoing reductions from baseline measures 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 207.4 tpd 
NOX and 6.4 tpd direct PM2.5, of which 78% (162 
tpd) and 73% (4.7 tpd), respectively, are attributed to CARB's baseline 
mobile source program.\278\ These on-going controls will thus result in 
additional reductions in NOX and direct PM2.5 
emissions between the 2013 base year and 2025 attainment year.\279\
---------------------------------------------------------------------------

    \278\ Id. at Ch. 4, Table 4-7.
    \279\ Id. at App. H, 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 SJV, Appendix H of the 2018 
PM2.5 Plan 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'').\280\ CARB's mobile source BACM analysis in Appendix D of the 2018 
PM2.5 Plan provides a more comprehensive overview of each of 
these programs and regulations, among many others.\281\ CARB's emission 
projections for mobile sources are presented in the Plan's emissions 
inventory.\282\
---------------------------------------------------------------------------

    \280\ 2018 PM2.5 Plan, App. H, H-21 and H-22. Because 
the ACC 2 measure is not scheduled for implementation until 2026 
(see 2018 PM2.5 Plan, Table 4-8), which is after the 
January 1, 2025 implementation deadline under 40 CFR 51.1011(b)(5) 
for control measures necessary for attainment by December 31, 2025, 
we are not reviewing this program as part of the control strategy in 
the SJV PM2.5 Plan.
    \281\ 2018 PM2.5 Plan, App. D, Ch. IV.
    \282\ 2018 PM2.5 Plan, App. B.
---------------------------------------------------------------------------

    The Truck and Bus Regulation, first adopted in 2008 and amended in 
2011, has rolling compliance deadlines based on truck engine model year 
(MY). CARB's implementation of the Truck and Bus Regulation includes 
phase-in requirements for PM2.5 and NOX emissions 
reductions that began in 2012 and require nearly all pre-2010 vehicles 
to have exhaust emissions meeting 2010 MY engine emission levels by 
2023.\283\ The 2010 MY engines include particulate filters for direct 
PM2.5 control. By 2016, the particulate filter requirement 
for trucks with a gross vehicle weight rating greater than 26,001 
pounds was fully implemented in the SJV and all heavier trucks with 
1995 and older model year engines were required to have a 2010 engine 
installed or to be replaced by a truck with a 2010 MY engine.\284\
---------------------------------------------------------------------------

    \283\ The State's quantitative milestone report for the 2019 
milestone indicates that the requirement for heavier trucks to 
install diesel particulate filters was fully implemented by 2016. 
CARB and SJVUAPCD, ``2019 Quantitative Milestone Report for the 2012 
PM2.5 NAAQS,'' 7, submitted by letter dated January 13, 
2020, from Richard W. Corey, Executive Officer, CARB, to Mike 
Stoker, Regional Administrator, EPA Region IX, with enclosures, 7.
    \284\ Id.
---------------------------------------------------------------------------

    For non-road vehicles, CARB adopted the Off-Road Regulation in 2007 
to regulate vehicles used in construction, mining, and other industrial 
applications. The Off-Road Regulation requires owners to (1) replace 
older engines or vehicles with newer, cleaner models, (2) retire older 
vehicles or reduce their use, or (3) apply retrofit exhaust 
controls.\285\ Beginning in 2014 for large fleets and in 2017 for 
medium fleets, non-road fleets are required to meet increasingly 
stringent fleet average indices over time.\286\ These indices reflect a 
fleet's overall PM and NOX emissions rates by model year and 
horsepower.
---------------------------------------------------------------------------

    \285\ 2019 QM Report, 9.
    \286\ A fleet average index is an indicator of a fleet's overall 
emissions rate of particulate matter and NOX based on the 
horsepower and model year of each engine in the fleet.
---------------------------------------------------------------------------

    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 2018 PM2.5 Plan 
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.\287\ These measures include seven rule amendments 
that the District adopted in 2019 through 2021, as discussed in section 
IV.F.3.c of this proposed rule and tabulated in Table IV-B of the EPA's 
2012 Annual PM2.5 TSD.
---------------------------------------------------------------------------

    \287\ 2018 PM2.5 Plan, App. H, Table H-2.
---------------------------------------------------------------------------

    With respect to the 2022 milestone year, Rule 4354 was amended in 
2011 to lower certain limits on emissions of NOX, 
SOX, and PM10 from container glass, flat glass, 
and fiberglass manufacturing facilities. Rule 4702 was amended in 2013 
to lower the NOX and SOX emission limits for 
various types of internal combustion engines rated at 25 brake 
horsepower or greater. The District amended Rule 4901 in 2019 to lower 
the thresholds at which ``No Burn'' days will be imposed to limit 
direct PM2.5 emissions from high-polluting wood burning 
heaters and fireplaces during the November through February timeframe 
in three ``hot spot'' counties (Fresno, Kern, and Madera), with 
implementation beginning November 1, 2019. These rules contribute to 
additional emission

[[Page 74342]]

reductions of direct PM2.5 and NOX from the 2013 
base year to the 2022 RFP milestone year. Additional District measures 
to control sources of direct PM2.5 and NOX are 
also presented in the Plan's BACM/MSM analyses and reflected in the 
Plan's baseline emission projections.\288\
---------------------------------------------------------------------------

    \288\ 2018 PM2.5 Plan, App. B and App. C.
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    For the remainder of the emission reductions necessary for 
attainment, the SJV PM2.5 Plan identifies a series of 
additional CARB and District commitments to achieve emission reductions 
through additional control measures and incentive programs that will 
contribute to attainment of the 2012 annual PM2.5 NAAQS by 
2025, as discussed in section IV.F.3.c of this proposed rule. For 
mobile sources, CARB's commitment identifies a list of 12 regulatory 
measures and 3 incentive-based measures that CARB has committed to 
propose to its Board for consideration by specific dates.\289\ For 
stationary and area sources, the District's commitment identifies a 
list of nine regulatory measures and three incentive-based measures 
that the District has committed to propose to its Board for 
consideration by specific dates.\290\ Both CARB and the District have 
committed to achieve specific amounts of reductions in direct 
PM2.5 and NOX emissions by 2025, either through 
implementation of these listed measures or through implementation of 
other control measures that achieve the necessary amounts of emission 
reductions by 2025.\291\
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    \289\ 2018 PM2.5 Plan, Chapter 4, Table 4-8 and CARB 
Resolution 18-49, 5. Table 4-8 of the 2018 PM2.5 Plan 
lists 14 State regulatory measures, but we are excluding from our 
review the ACC 2 measure and the ``Cleaner In-Use Agricultural 
Equipment'' measure because these measures are scheduled for 
implementation in 2026 and 2030, respectively, which fall after the 
January 1, 2025 implementation deadline for control measures 
necessary for attainment by December 31, 2025. 40 CFR 51.1011(b)(5).
    \290\ 2018 PM2.5 Plan, Chapter 4, Table 4-4 and 
SJVUAPCD Governing Board Resolution 18-11-16, 10-11.
    \291\ SJVUAPCD Governing Board Resolution 18-11-16, 10-11 and 
CARB Resolution 18-49, 5.
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    The 2018 PM2.5 Plan discusses a number of additional 
control measures that the District may adopt to meet its aggregate 
tonnage commitment, including additional control requirements for 
flares; boilers, steam generators, and process heaters of various 
sizes; glass melting furnaces; internal combustion engines; 
conservation management practices for agricultural operations; and 
commercial under-fired charbroilers.\292\ In addition, the Plan states 
that the District intends to use incentive programs to reduce emissions 
of direct PM2.5 and NOX from internal combustion 
engines used in agricultural operations, commercial under-fired 
charbroilers, and residential woodburning devices.\293\ The 2018 
PM2.5 Plan establishes deadlines between 2018 and 2023 for 
CARB to take action on and begin implementing the 15 additional mobile 
source control measures that CARB has committed to propose to its Board 
\294\ and similar deadlines between 2019 and 2024 for the District to 
take action on and begin implementing the 12 additional District 
control measures that the District has committed to propose to its 
Board.\295\
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    \292\ 2018 PM2.5 Plan, Chapter 4, 4-12 and 4-15 to 4-
22.
    \293\ Id. at 4-22 to 4-24.
    \294\ 2018 PM2.5 Plan, Chapter 4, Table 4-8 and CARB 
Resolution 18-49, 5.
    \295\ 2018 PM2.5 Plan, tables 4-4 and 4-5, and 
SJVUAPCD Governing Board Resolution 18-11-16, 10-11.
---------------------------------------------------------------------------

    The anticipated implementation schedule for new CARB measures is 
presented in Table 4-8 of the 2018 PM2.5 Plan and the 
anticipated implementation schedule for new District measures is 
presented both in Table H-2 of Appendix H and in Tables 4-4 and 4-5 of 
the 2018 PM2.5 Plan. We summarize these schedules, as well 
as the compliance schedules for those District measures that have been 
adopted by December 2021, in Table IV-A (for CARB measures) and Table 
IV-B (for District measures) of the EPA's 2012 Annual PM2.5 
TSD. For example, implementation of Rule 4901 began November 1, 2019, 
and implementation for Rules 4311, 4306, 4320, and 4702 will begin 
December 31, 2023.
    Section H.1.3 of Appendix H of the Plan provides the State's and 
District's justifications for the stepwise approach to meeting the RFP 
requirement and the related implementation schedules for new or revised 
control measures. These justifications include the time needed to 
engage in the rulemaking process, including time for state and local 
public processes; the need to provide time for industry to comply with 
new regulatory requirements; the need to resolve feasibility issues for 
emerging technologies; and, for CARB mobile source measures, the need 
for affected industries to prepare technologies and infrastructure for 
market-scale adoption.
    For example, Appendix H of the 2018 PM2.5 Plan states 
that ``time after rule adoption will be necessary for unit 
manufacturers and vendors to make available compliant equipment, and 
for facility operators to source, purchase, and install new units or 
compliant retrofit equipment. Dependent on the source category, 
construction of controls will include engineering, site preparation and 
infrastructure upgrades, unit installation, and operator training on 
proper operation.'' \296\
---------------------------------------------------------------------------

    \296\ 2018 PM2.5 Plan, App. H, H-7.
---------------------------------------------------------------------------

    CARB and the District discussed in greater detail a number of 
specific implementation challenges as part of their justification for 
meeting the RFP requirement by the stepwise approach in the Plan. For 
NOX, the new control measures that CARB and the District 
anticipate implementing toward the end of the attainment period can be 
found in tables 4-4, 4-5, and 4-8 of the 2018 PM2.5 Plan. 
Appendix H of the 2018 PM2.5 Plan provides the following 
explanation for the need to implement the listed measures in a stepwise 
manner:
    ``The objective of many of CARB's new measures is to introduce or 
advance innovative technologies in early stages of development or 
market penetration. In the case of technology-forcing regulations, . . 
. time is needed by the affected industry to ready the technologies, 
including infrastructure, for market-scale adoption, and would have 
been discussed previously by CARB and stakeholders during the measure 
development phase. The time required to facilitate new and innovative 
technologies is a principle driver of the timeline for control measure 
implementation CARB laid out in Table 4-8.'' \297\
---------------------------------------------------------------------------

    \297\ 2018 PM2.5 Plan, App. H, H-8.
---------------------------------------------------------------------------

    CARB provided more specific information regarding two of these 
measures on pages H-9 and H-10 of Appendix H. For instance, the 
development of Heavy-Duty I/M was affirmed by California legislative 
action in 2019, and CARB was working on program design and 
infrastructure to implement new legislative direction.\298\ For the 
California Low-NOX Engine Standard, the implementation 
timeline has been influenced by a multi-year research program to assess 
the feasibility of this standard. The development of these measures has 
now culminated in adoption of Heavy-Duty I/M in December 2021 and the 
California Low-NOX Engine Standard in August 2020, with 
implementation beginning in 2023 and 2024, respectively.
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    \298\ California Senate Bill 210, signed September 20, 2019.
---------------------------------------------------------------------------

    The new direct PM2.5 measures that CARB and the District 
anticipate implementing toward the end of the attainment period can be 
found in Tables 4-4, 4-5, and 4-8 of the 2018 PM2.5 Plan. 
CARB's additional measures are expected to achieve 0.9 tpd of direct

[[Page 74343]]

PM2.5 emission reductions \299\ and the District's 
additional measures are expected to achieve 1.3 tpd of direct 
PM2.5 emission reductions by 2025.\300\ New or revised 
District measures are thus expected to achieve a significant portion of 
CARB and the District's 2.2 tpd direct PM2.5 emission 
reduction commitment for the 2025 attainment year.
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    \299\ 2018 PM2.5 Plan, Ch. 4, Table 4-9.
    \300\ Id. at Table 4-3. As discussed in section IV.F.3.d of this 
proposed rule, pending final approval of the Agricultural Burning 
Phase-out Measure, the District would have met its direct 
PM2.5 emission reduction commitment of 1.3 tpd and, in 
fact, exceeded it by 0.13 tpd.
---------------------------------------------------------------------------

    As discussed in section IV.F.3.c of this proposed rule, CARB and 
the District have adopted 18 measures of the 27 control measure 
commitments, a majority of which will achieve direct PM2.5 
emission reductions in the SJV. In doing so, CARB and the District 
concurrently developed and adopted measures for wide-ranging emission 
sources such as heavy-duty trucks, agricultural equipment, local 
trucks, small off-road engines, flares, boilers, stationary internal 
combustion engines, and residential wood burning.
    With respect to the commercial charbroiling, according to 
information provided in Appendix C of the 2018 PM2.5 Plan, 
the costs associated with retrofitting control technology onto 
equipment at existing restaurants and maintaining such equipment can be 
prohibitively expensive, especially for smaller restaurants.\301\ 
Because of ongoing uncertainties about the technological and economic 
feasibility of controls for under-fired charbroiling (UFC), the 
District adopted a set of registration and reporting provisions in a 
revised version of Rule 4692 that required owners and operators of 
commercial cooking operations with UFCs to register each unit and to 
submit, by January 1, 2019, a one-time informational report providing 
information about the UFC and its operations. CARB submitted this 
revised rule to the EPA on November 16, 2018, and the EPA approved the 
rule amendments into the California SIP on September 14, 2020.\302\
---------------------------------------------------------------------------

    \301\ 2018 PM2.5 Plan, App. C, C-209 to C-210.
    \302\ 85 FR 56521.
---------------------------------------------------------------------------

    While the District has not proposed to its Governing Board 
amendments to Rule 4692 that impose new control requirements on UFCs, 
in presenting the District's ``Commercial Underfired Charbroiling 
Emission Reduction Strategy'' to its Governing Board on December 17, 
2020, the District expressed continued difficulty in identifying 
feasible control technologies for under-fired charbroiling restaurants, 
particularly given the ``unprecedented impacts of the COVID-19 pandemic 
to the restaurant industry'' that limited revenue streams.\303\ 
Nevertheless, the District continues to work on this source category, 
including the evaluation of ``potential amendments to Rule 4692 in the 
near future.'' \304\
---------------------------------------------------------------------------

    \303\ SJVUAPCD, ``Item Number 11: Adopt Proposed Commercial 
Under-fired Charbroiling Emission Reduction Strategy,'' December 17, 
2020, 2.
    \304\ 2021 Progress Report, 9.
---------------------------------------------------------------------------

    The 2018 PM2.5 Plan also shows that a portion of the 
necessary direct PM2.5 emission reductions in 2025 (0.32 of 
2.2 tpd) is expected to result from a revised version of the District's 
Conservation Management Practices (CMP) rule (Rule 4550), which is 
designed to reduce particulate emissions from agricultural 
operations.\305\ The District hosted a public scoping meeting on 
potential amendments to Rule 4550 on December 16, 2021,\306\ and 
anticipates proposing this revised rule to the SJVUAPCD Governing Board 
in 2022 and implementing it beginning in 2024.\307\ As explained in 
Appendix C of the 2018 PM2.5 Plan, an important step in 
developing effective PM2.5 controls for dust from 
agricultural operations is to develop an understanding of the 
effectiveness of CMPs on controlling PM2.5 emissions in the 
Valley.\308\ Towards this end, the District intends to work with 
stakeholders and researchers to evaluate the feasibility and 
effectiveness of additional control measures to reduce PM2.5 
emissions, including: Tilling and other land preparation activities; 
selection of conservation tillage as a CMP for croplands; and CMPs on 
fallow lands that are tilled or otherwise worked with implements of 
husbandry (e.g., a farm tractor drawing a trailer with crops) to reduce 
windblown PM emissions from disturbed fallowed acreage.\309\
---------------------------------------------------------------------------

    \305\ 2018 PM2.5 Plan, Ch. 4, Table 4-3.
    \306\ SJVUAPCD, ``Notice of Public Scoping Meeting, Rule 4550 
(Conservation Management Practices),'' December 2, 2021. The 
District also held a series of workshops from January to March 2020 
with the stated goal of ``assisting growers and dairy families in 
understanding and complying with District Rule 4550.'' SJVUAPCD, 
``Air Quality Workshop Series Focused on Conservation Management 
Practices (CMP) Plans,'' available at https://www.valleyair.org/Workshops/postings/2020/2020_CMP/notice.pdf.
    \307\ 2018 PM2.5 Plan, Ch. 4, Table 4-4.
    \308\ 2018 PM2.5 Plan, App. C, C-203.
    \309\ Id. at C-203.
---------------------------------------------------------------------------

(b) Quantitative Milestones
    Appendix H of the 2018 PM2.5 Plan identifies October 15 
milestone dates for the 2019 and 2022 RFP milestone years, the 2025 
attainment year, and a post-attainment milestone year of 2028.\310\ 
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,\311\ as shown in Table 6 of this 
proposed rule, 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.\312\
---------------------------------------------------------------------------

    \310\ 2018 PM2.5 Plan, App. H, Table H-12.
    \311\ Id. at Table H-5.
    \312\ Id. at H-23 to H-24 (for CARB milestones) and H-20 to H-22 
(for District milestones).
---------------------------------------------------------------------------

    We note, however, that while quantitative milestones are required 
for 2019 in the context of the Moderate area plan for the 2012 annual 
PM2.5 NAAQS in the SJV (corresponding to the 4.5 years after 
the date of designation), we have already evaluated and approved the 
State's quantitative milestones for 2019, as supplemented by the 2018 
PM2.5 Plan.\313\ Therefore, the EPA is not evaluating the 
2019 milestones for purposes of the State's Serious area plan for the 
2012 annual PM2.5 NAAQS in the SJV. Similarly, given that 
the 2018 PM2.5 Plan includes a demonstration of attainment 
by the 10th calendar year following designations, quantitative 
milestones are not required beyond 10.5 years after the date of 
designation (i.e., October 15, 2025). Therefore, the EPA is not 
evaluating the 2028 milestones for purposes of the submitted Serious 
area plan.
---------------------------------------------------------------------------

    \313\ 86 FR 67343, 67346.
---------------------------------------------------------------------------

    The 2018 PM2.5 Plan estimates that emissions of direct 
PM2.5 and NOX will generally decline from the 
2013 base year to the 2025 attainment year and that direct 
PM2.5 and NOX are emitted by a large number and 
range of sources in the SJV. With respect to emission reductions, the 
2018 PM2.5 Plan relies on the baseline measures reflected in 
the Plan's emissions inventory to demonstrate RFP through 2022.\314\
---------------------------------------------------------------------------

    \314\ 2018 PM2.5 Plan, App. H, H-4 to H-15.
---------------------------------------------------------------------------

    In addition to these baseline measures, the 2018 PM2.5 
Plan's control strategy includes specific control measure commitments 
for purposes of attaining the 2012 annual PM2.5 NAAQS by 
2025, including commitments by CARB and the District to develop and 
propose to their respective boards specific regulatory and incentive-
based measures identified in the plan by specific years leading up to 
2025, including 2019 and 2022.\315\ Although

[[Page 74344]]

the attainment demonstration does not rely on these control measure 
commitments for emission reductions until 2025,\316\ the RFP and 
quantitative milestone elements of the 2018 PM2.5 Plan rely 
on these control measure commitments to demonstrate that the plan 
requires RFP toward attainment.\317\
---------------------------------------------------------------------------

    \315\ CARB Resolution 18-49, 5; 2018 PM2.5 Plan, Ch. 
4, Table 4-8; 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''); 
CARB 2018 Staff Report, 14; SJVUAPCD Governing Board Resolution 18-
11-16, 10-11; 2018 PM2.5 Plan, Ch. 4, tables 4-4 and 4-5; 
and 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'').
    \316\ 2018 PM2.5 Plan, Ch. 4, Table 4-3 (``Emission 
Reductions from District Measures'') and Table 4-9 (``San Joaquin 
Valley Expected Emission Reductions from State Measures'').
    \317\ 2018 PM2.5 Plan, App. H, H-4 to H-10 
(describing commitments by CARB and SJVUAPCD to adopt additional 
measures to fulfill tonnage commitments for 2024 and 2025, including 
``action'' and ``implementation'' dates occuring before 2024 to 
ensure expeditious progress toward attainment).
---------------------------------------------------------------------------

    For the 2022 milestone year, Appendix H of the 2018 
PM2.5 Plan describes the District's quantitative milestone 
as a report on ``[t]he status of SIP measures adopted between 2019 and 
2022 as per the schedule included in the adopted Plan, including 
Residential Wood Burning Strategy and Commercial Under-Fired 
Charbroiler incentive-based strategy.'' \318\ The schedule for 
development of new or revised SIP measures in the 2018 PM2.5 
Plan identifies ``action dates'' between 2019 and 2022 for 12 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 4354 (``Glass Melting Furnaces'').\319\
---------------------------------------------------------------------------

    \318\ 2018 PM2.5 Plan, App. H, H-20.
    \319\ 2018 PM2.5 Plan, Ch. 4, 4-12 and 4-13 (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).
---------------------------------------------------------------------------

    Appendix H describes CARB's quantitative milestone as a report on 
two measure-specific milestones: (1) Actions taken between 2019 and 
2022 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, and (2) the ``status of SIP 
measures adopted between 2019 and 2022, including Advanced Clean Cars 2 
and the Heavy-Duty Vehicle Inspection and Maintenance Program.'' \320\ 
The schedule for development of new or revised CARB measures in the 
2018 PM2.5 Plan identifies ``action'' dates between 2019 and 
2022 for 13 CARB measures listed in Table 4-8 of Chapter 4, including, 
for example, Heavy-Duty I/M, the SORE regulation, and the Low-Emission 
Diesel Fuel Requirement.\321\
---------------------------------------------------------------------------

    \320\ 2018 PM2.5 Plan, App. H, H-23.
    \321\ 2018 PM2.5 Plan, Ch. 4, 4-28 (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 CARB 2018 
Staff Report, 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 2025 attainment year, Appendix H of the 2018 
PM2.5 Plan describes the District's quantitative milestone 
as a report on ``[i]mplementation of amendments to Residential Wood 
Burning Strategy, including any regulatory amendments and enhancements 
to the District Burn Cleaner incentive program,'' ``[i]mplementation of 
amendments to the Commercial Under-Fired [Charbroiler] Strategy, 
including any regulatory amendments and implementation of related 
incentive-based strategy,'' and ``[t]he status of SIP measures adopted 
between 2022 and 2025 as per the schedule included in the adopted 
Plan.'' \322\ The schedule for development of new or revised SIP 
control measures in the 2018 PM2.5 Plan identifies ``action 
dates'' between 2022 and 2025 for one District measure: Rule 4550 
(``Conservation Management Practices'').\323\
---------------------------------------------------------------------------

    \322\ 2018 PM2.5 Plan, App. H, H-20 to H-21.
    \323\ 2018 PM2.5 Plan, Ch. 4, 4-12 (Table 4-4). 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).
---------------------------------------------------------------------------

    Appendix H describes CARB's quantitative milestone as a report on 
three measure-specific milestones: (1) ``[i]dentify the number of 
pieces of agricultural equipment turned over to Tier 4 Final due to the 
Accelerated Turnover of Agricultural Tractors Measure through 2025;'' 
(2) ``[i]dentify the number of trucks and buses turned over to a low-
NOX engine or cleaner due to the Accelerated Turnover of 
Trucks and Buses Measure through 2025;'' and (3) ``[t]he status of SIP 
measures adopted between 2022 and 2025, including the proposed Cleaner 
In-Use Agricultural Equipment Measure to incentivize the penetration of 
cleaner agricultural equipment used in California.'' \324\ The schedule 
for development of new or revised CARB measures in the 2018 
PM2.5 Plan identifies ``action'' dates between 2022 and 2025 
for one CARB measure: The Cleaner In-Use Agricultural Equipment 
measure.\325\
---------------------------------------------------------------------------

    \324\ 2018 PM2.5 Plan, App. H, H-23.
    \325\ 2018 PM2.5 Plan, Ch. 4, 4-28 (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 CARB 2018 
Staff Report, 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).
---------------------------------------------------------------------------

3. EPA Evaluation and Proposed Action
(a) Reasonable Further Progress
    We have evaluated the RFP demonstration in Appendix H of the 2018 
PM2.5 Plan and, for the following reasons, propose 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 and the District's aggregate tonnage commitments, 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 2018 PM2.5 Plan and in 
Table H-2 of Appendix H. The 2018 PM2.5 Plan documents the 
State's and District's conclusion that they are implementing all BACM 
and BACT for direct PM2.5 and NOX emissions in 
the Valley as expeditiously as practicable.\326\
---------------------------------------------------------------------------

    \326\ The BACM/BACT control strategy that provides the basis for 
these emissions projections is described in Chapter 4, App. C, and 
App. D of the 2018 PM2.5 Plan.
---------------------------------------------------------------------------

    Second, the RFP demonstration contains projected emission levels 
for direct PM2.5 and NOX for each applicable 
milestone year as required by 40 CFR 51.1012(a)(2). These projections 
are based on continued implementation of the existing control measures 
in the area (i.e., baseline measures) and commitments to achieve 
additional reductions from new measures by 2025, 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 
reasonable further progress toward attainment between the 2013 baseline 
year and the 2025 attainment year as required by 40 CFR 51.1012(a)(3). 
Tables 7 and 8 of this proposed rule show decreases in emissions levels 
in each milestone year, leading to the achievement of the reductions 
required for attainment in 2025.

[[Page 74345]]

    Finally, the RFP demonstration shows that overall pollutant 
emissions will be at levels that reflect stepwise progress between the 
base year and the attainment year and provides a justification for the 
selected implementation schedule, as required by 40 CFR 51.1012(a)(4). 
The steeper decline in emissions by 2025 is primarily due to 
commitments by CARB and the District to achieve reductions from new 
control measures by 2025. CARB and the District's justifications for 
their selected implementation schedules, i.e., for the delay in their 
respective commitments to achieve emissions reductions from new or 
revised control measures, include the time needed for rulemaking 
processes, the time needed for industry to comply with new regulatory 
requirements, the need to resolve feasibility issues for emerging 
technologies, and the time needed to prepare technologies and 
infrastructure for market-scale adoption.
    We note that although both CARB and the District have committed to 
propose to their respective boards certain new or revised control 
measures in the years leading up to the 2025 attainment year, the only 
enforceable commitment in the Plan that requires adoption of control 
measures is the tonnage commitment for reductions by 2025, which 
provides the basis for the stepwise approach to RFP.
(b) Quantitative Milestones
    Appendix H of the 2018 PM2.5 Plan identifies milestone 
dates for the Serious plan (i.e., October 15, 2022, and October 15, 
2025) that are consistent with the requirements of 40 CFR 
51.1013(a)(2)(i) and target emissions levels for direct 
PM2.5 and NOX to be achieved by these milestone 
dates through implementation of the Plan's control strategy. These 
target emission levels and associated control requirements provide for 
objective evaluation of the area's progress towards attainment of the 
2012 annual PM2.5 NAAQS.
    CARB's quantitative milestones in Appendix H are to take action on 
or to implement specific measures listed in the State's control measure 
commitments that apply to heavy-duty trucks and buses, light-duty 
vehicles, and non-road equipment sources and may provide substantial 
reductions in emissions of direct PM2.5 and NOX 
from mobile sources in the SJV. Similarly, the District's quantitative 
milestones in Appendix H are to take action on or to implement specific 
measures listed in the District's control measure commitments that 
apply to sources such as residential wood burning, conservation 
management practices, glass melting furnaces, and internal combustion 
engines and that may provide substantial reductions in emission of 
direct PM2.5 and NOX from stationary sources. 
These milestones provide an objective means for tracking CARB and the 
District's progress in implementing their respective control measure 
and aggregate tonnage commitments and, thus, provide for objective 
evaluation of the SJV'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 2012 annual 
PM2.5 NAAQS in the SJV.
    We note that on January 13, 2020, CARB submitted the ``2019 
Quantitative Milestone Report for the 2012 PM2.5 NAAQS 
(``SJV 2019 QM Report'') for the Moderate area plan to the EPA,\327\ 
which the EPA is currently reviewing.
---------------------------------------------------------------------------

    \327\ Letter dated January 13, 2020, from Richard W. Corey, 
Executive Officer, CARB, to Mike Stoker, Regional Administrator, EPA 
Region IX, with enclosures.
---------------------------------------------------------------------------

H. Contingency Measures

1. Requirements for Contingency Measures
    Under CAA section 172(c)(9), states required to make an attainment 
plan SIP submission must include contingency measures that they will 
implement if the area fails to meet RFP (``RFP contingency measures'') 
or fails to attain the NAAQS by the applicable attainment date 
(``attainment contingency measures''). Under the PM2.5 SIP 
Requirements Rule, states must include contingency measures that will 
be implemented following a determination by the EPA that the state has 
failed: (1) To meet any RFP requirement in the approved attainment 
plan; (2) to meet any quantitative milestone in the approved attainment 
plan; (3) to submit a required quantitative milestone report; or (4) to 
attain the applicable PM2.5 NAAQS by the applicable 
attainment date.\328\ Contingency measures must be fully adopted rules 
or control measures that are ready to be implemented quickly and 
without significant further action by the state or the EPA upon failure 
to meet RFP or failure of the area to meet the relevant NAAQS by the 
applicable attainment date.\329\
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    \328\ 40 CFR 51.1014(a).
    \329\ 81 FR 58010, 58066 and General Preamble Addendum, 42015.
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    The purpose of contingency measures is to continue progress in 
reducing emissions while a state revises its SIP to meet the missed RFP 
requirement or to correct ongoing nonattainment. Neither the CAA nor 
the EPA's implementing regulations establish a specific amount of 
emission reductions that implementation of contingency measures must 
achieve, but the EPA recommends that contingency measures should 
provide for emission reductions equivalent to approximately one year of 
reductions needed for RFP in the nonattainment area, calculated as the 
overall level of reductions needed to demonstrate attainment divided by 
the number of years from the base year to the attainment year. In 
general, we expect all actions needed to effect full implementation of 
the measures to occur within 60 days after the EPA notifies the state 
of a failure to meet RFP or to attain.\330\
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    \330\ 81 FR 58010, 58066. See also General Preamble 13512, 
13543-13544, and General Preamble Addendum, 42014-42015.
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    To satisfy the requirements of 40 CFR 51.1014, the contingency 
measures adopted as part of a PM2.5 attainment plan must 
consist of control measures for the area that are not otherwise 
required to meet other attainment plan requirements (e.g., to meet 
RACM/RACT requirements) and must specify the timeframe within which 
their requirements become effective following any of the EPA 
determinations specified in 40 CFR 51.1014(a). To meet CAA section 
172(c)(9), contingency measures must be measures that are triggered and 
implemented only after the EPA determines that an area fails to meet 
RFP requirements or to attain by the applicable attainment date, and 
the state must not have begun to implement such measures before this 
determination is made. Thus, already-implemented measures cannot serve 
as contingency measures under CAA section 172(c)(9).\331\
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    \331\ See Bahr v. EPA, 836 F.3d 1218, 1235 (9th Cir. 2016), 
Sierra Club v. EPA, 985 F.3d 1055 (DC Cir. 2021), and Assoc. of 
Irritated Residents v. EPA, 10 F.4th 937 (9th Cir. 2021).
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2. Summary of State's Submission
    The 2018 PM2.5 Plan addresses the contingency measure 
requirement for the 2012 annual PM2.5 NAAQS by reference to 
the contingency measure portion of a separate December 2018 SIP 
submission that involved enhanced enforcement of CARB regulations in 
the SJV, a commitment to amend the District's residential wood burning 
rule (i.e., District Rule 4901) to include contingent provisions, and 
emissions estimates for the year following the attainment year for use 
in evaluating whether the emissions reductions from the contingency 
measures are

[[Page 74346]]

sufficient.\332\ In January 2021, CARB withdrew the enhanced 
enforcement portion of the December 2018 SIP submission as it pertained 
to the 2012 annual PM2.5 NAAQS in the SJV.\333\
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    \332\ 2018 PM2.5 Plan, App. H (revised February 11, 
2020), H-24 to H-26.
    \333\ Letter dated January 8, 2021, from Richard W. Corey, 
Executive Officer, CARB, to John W. Busterud, Regional 
Administrator, EPA Region IX, with enclosures.
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    With respect to the District contingency measure, the 2018 
PM2.5 Plan states that the District will amend District Rule 
4901 to include a requirement that would be triggered should the EPA 
issue a final rulemaking that the SJV failed to meet a regulatory 
requirement necessitating implementation of a contingency measure.\334\ 
The District adopted amendments to Rule 4901 on June 20, 2019, 
including a contingency measure in section 5.7.3 of the amended rule, 
and CARB submitted the amended rule to the EPA for approval on July 22, 
2019.\335\ In this proposal, we are evaluating District Rule 4901, 
specifically, section 5.7.3, for compliance with the requirements for 
contingency measures for purposes of meeting the Serious area planning 
requirements for the 2012 annual PM2.5 NAAQS.
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    \334\ 2018 PM2.5 Plan, App. H, H-25.
    \335\ SJVUAPCD Rule 4901, as amended on June 20, 2019, was 
submitted electronically to the EPA on July 22, 2019, as an 
attachment to a letter dated July 19, 2019, from Richard W. Corey, 
Executive Officer, CARB, to Mike Stoker, Regional Administrator, EPA 
Region IX.
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    District Rule 4901 is designed to limit emissions generated by the 
use of wood burning fireplaces, wood burning heaters, and outdoor wood 
burning devices. The rule establishes requirements for the sale/
transfer, operation, and installation of wood burning devices and for 
advertising the sale of seasoned wood consistent with a moisture 
content limit within the SJV.
    The rule includes a two-tiered, episodic wood burning curtailment 
requirement that applies during four winter months, November through 
February. During a level one episodic wood burning curtailment, section 
5.7.1 prohibits any person from operating a wood burning fireplace or 
unregistered wood burning heater but permits the use of a properly 
operated wood burning heater that meets certification requirements and 
has a current registration with the District. Sections 5.9 through 5.11 
impose specific registration requirements on any person operating a 
wood burning fireplace or wood burning heater and section 5.12 imposes 
specific certification requirements on wood burning heater 
professionals. During a level two episodic wood burning curtailment, 
operation of any wood burning device is prohibited by section 5.7.2.
    Prior to the 2019-2020 wood burning season, the District imposed a 
level one curtailment when the PM2.5 concentration was 
forecasted to be between 20-65 [mu]g/m\3\ and imposed a level two 
curtailment when the PM2.5 concentration was forecasted to 
be above 65 [mu]g/m\3\ or the PM10 concentration was 
forecasted to be above 135 [mu]g/m\3\. In 2019, the District adopted 
revisions to Rule 4901 to lower the wood burning curtailment thresholds 
in the ``hot spot'' counties of Madera, Fresno, and Kern. The District 
lowered the level one PM2.5 threshold for these three 
counties from 20 [mu]g/m\3\ to 12 [mu]g/m\3\, and the level two 
PM2.5 threshold from 65 [mu]g/m\3\ to 35 [mu]g/m\3\. The 
District did not modify the curtailment thresholds for other counties 
in the SJV--those levels remained at 20 [mu]g/m\3\ for level one and 65 
[mu]g/m\3\ for level two.
    The District's 2019 revision to Rule 4901 also included the 
addition of a contingency measure in section 5.7.3 of the rule, 
requiring that 60 days following the effective date of an EPA final 
rulemaking that the SJV has failed to attain the 1997, 2006, or 2012 
PM2.5 NAAQS by the applicable attainment date, the 
PM2.5 curtailment levels for any county that has failed to 
attain the applicable standard will be lowered to the curtailment 
levels in place for hot spot counties. The District estimates that the 
potential emissions reduction in direct PM2.5 would be in 
the range of 0.014 tpd (if the contingency is triggered in Kings County 
but not the other non-hot-spot counties) to 0.387 tpd (if the 
contingency is triggered in all five of the non-hot-spot counties), but 
there would be no emissions reduction if, at the time of the 
determination of failure to attain the 2012 annual PM2.5 
NAAQS by the attainment date, violations of the 2012 annual 
PM2.5 NAAQS occurred only at monitors in the hot-spot 
counties.\336\ The corresponding potential NOX emissions 
reduction would be in the range of 0.002 tpd to 0.060 tpd, 
respectively, but as previously noted there would be no emissions 
reduction if the monitored violations occur in the hot-spot counties 
only.\337\
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    \336\ See Table B-13 in Appendix B from the District's Final 
Staff Report (June 20, 2019) for revisions to Rule 4901.
    \337\ NOX emissions reductions from the contingency 
measure are based on the District's estimates for direct 
PM2.5 emissions using the ratio of direct 
PM2.5 to NOX in Table 1 of the District's 
Final Staff Report (June 20, 2019) for revisions to Rule 4901.
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3. EPA Evaluation and Proposed Action
    We have evaluated the contingency measure element of the 2018 
PM2.5 Plan and associated contingency measure in District 
Rule 4901 (i.e., section 5.7.3 of the rule) against the requirements of 
CAA section 172(c)(9) and 40 CFR 51.1014 for both attainment and RFP 
contingency measures, and the related requirements for submission of 
quantitative milestone reports and compliance with quantitative 
milestones. We propose to find that the contingency measure element of 
the 2018 PM2.5 Plan (and contingency measure in District 
Rule 4901) is inadequate to meet the Serious area contingency measure 
requirements for the 2012 annual PM2.5 NAAQS for several 
reasons.
    As noted in our summary of the State's submission, the contingency 
measure in District Rule 4901 is structured to provide for 
implementation if the area fails to attain the 2012 annual 
PM2.5 NAAQS, not before, and is therefore consistent with 
the requirement under CAA section 172(c)(9) that contingency measures 
be prospective and conditional, rather than already being implemented. 
However, as structured, the contingency measure of Rule 4901 (i.e., 
section 5.7.3) would provide for emissions reductions only in Kings, 
Merced, San Joaquin, Stanislaus, and/or Tulare counties, not the ``hot 
spot'' counties of Fresno, Kern, and Madera, and only if a violating 
monitoring site (i.e., a site where the collected data represent a 
violation of the NAAQS) is located in such county. In other words, if 
the EPA's determination of failure to attain the NAAQS by the 
applicable attainment date indicates violations at monitoring sites in 
Fresno and Kern (``hot spot'' counties) and Tulare (non-hot-spot 
county) counties, the contingency measure would provide for emissions 
reductions by lowering the wood burning curtailment thresholds in 
Tulare County only. The ``hot spot'' counties are already subject to 
the lower wood burning curtailment thresholds in the rule and thus 
would not be affected by the finding of failure to attain determination 
and the other non-``hot spot'' counties (i.e., other than Tulare County 
in this example) would not be subject to the lower wood burning 
curtailment thresholds.
    In accordance with 40 CFR 51.1014, the contingency measure in 
District Rule 4901 identifies a specific triggering mechanism. In this 
case, the triggering mechanism in the rule is the EPA's final 
determination that the SJV has failed to attain the 2012 annual 
PM2.5 NAAQS by

[[Page 74347]]

the applicable attainment date.\338\ The rule also specifies a 
timeframe within which its requirements become effective after a 
failure-to-attain determination (i.e., on and after 60 days from the 
effective date of the EPA's final determination), and would take effect 
with minimal further action by the state or the EPA. However, the 
contingency measure in District Rule 4901 does not address the 
potential for State failures to meet a quantitative milestone, submit a 
quantitative milestone report, or failure to meet an RFP 
requirement.\339\
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    \338\ Section 5.7.3 of Rule 4901 states that ``the District 
shall notify the public of an Episodic Curtailment for the 
PM2.5 curtailment levels described in Sections 5.7.1.2 
and 5.7.2.2 for any county that has failed to attain the applicable 
standard.'' (emphasis added) We interpret this to mean that the 
District would apply the more stringent curtailment provisions for 
any county identified in the EPA's final rule making the 
determination that the SJV failed to attain the applicable 
PM2.5 NAAQS.
    \339\ We note that section 5.7.3 of District Rule 4901 applies 
the lower thresholds ``on and after sixty days following the 
effective date of EPA final rulemaking,'' which is appropriate as a 
contingency measure trigger for a failure to attain by the 
applicable attainment date given that the EPA conducts rulemaking to 
make such determinations. However, for the three other contingency 
triggers, i.e., State failures to meet a quantitative milestone, 
submit a quantitative milestone report, or failure to meet an RFP 
requirement, the EPA may not conduct rulemaking but instead make the 
determinations through correspondence directly to the State. Thus, 
we recommend that section 5.7.3 of District Rule 4901 be amended to 
refer to ``EPA final determinations'' rather than to ``EPA final 
rulemaking'' if the rule is amended to include the additional 
contingency measure triggers.
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    In addition, the contingency measure provision of Rule 4901 is not 
structured to achieve any additional emissions reductions if the EPA 
finds that monitoring locations in the ``hot spot'' counties (i.e., 
Fresno, Kern, or Madera Counties) are the only ones in the SJV that are 
violating the 2012 annual PM2.5 NAAQS as of the attainment 
date. To qualify as a contingency measure, a measure must be structured 
to achieve emissions reductions if triggered, and the contingency 
measure of District Rule 4901 provides for such reductions only under 
certain circumstances. If the District intends to retain a contingency 
provision in Rule 4901, the District should revise the rule to provide 
for additional emissions reductions in the SJV (if triggered) 
regardless of which monitoring site(s) is determined to be violating 
the 2012 annual PM2.5 NAAQS as of the attainment date.\340\
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    \340\ The EPA believes that the most straightforward remedy 
under these circumstances would be for the District to amend section 
5.7.3 of Rule 4901 to extend the lower wood burning curtailment 
thresholds region-wide if the EPA determines that the area has 
failed to attain the 2012 annual PM2.5 NAAQS by the 
applicable attainment date.
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    Next, we considered the adequacy of the contingency measure in 
section 5.7.3 of District Rule 4901 from the standpoint of the 
magnitude of emissions reductions the measure would provide if 
triggered. Neither the CAA nor the EPA's implementing regulations for 
the PM2.5 NAAQS establish a specific amount of emissions 
reductions that implementation of contingency measures must achieve, 
but the EPA has long recommended that contingency measures should 
provide for emissions reductions approximately equivalent to one year's 
worth of RFP, which in the case of the Serious area attainment plan 
amounts to reductions of approximately 0.5 tpd of direct 
PM2.5 and 17.3 tpd of NOX for the 2012 annual 
PM2.5 NAAQS in the SJV.\341\ As noted in our summary of the 
State's submission, the emissions reductions from the contingency 
measure in District Rule 4901 would amount to approximately 0.00 tpd to 
0.387 tpd of direct PM2.5, which equates to approximately 0% 
to 77% of one year's worth of RFP for direct PM2.5. With 
respect to NOX emissions reductions, the contingency measure 
in District Rule 4901 would amount to approximately 0.00 tpd to 0.06 
tpd, which equates to approximately 0% to 0.3% of one year's worth of 
RFP for NOX. As such, the emissions reductions from the 
contingency measure in section 5.7.3 of Rule 4901, if triggered, would 
be far less than one year's worth of progress with respect to the 2012 
annual PM2.5 NAAQS in the SJV. District Rule 4901 alone, and 
as currently formulated, would provide insufficient emission reductions 
to meet the contingency measures requirement.
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    \341\ The calculation of one year's worth of RFP is based on 
dividing the values in column E of table H-6 of Appendix H (updated 
February 11, 2020) of the 2018 PM2.5 Plan by 12, i.e., 
the number of years between 2013 and 2025. We consider that the fact 
that this element focuses only on direct PM2.5 and 
NOX (and not ammonia, SO2, and VOC) is 
acceptable in light of our proposed approval of the precursor 
demonstration in section IV.B of this proposed rule.
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    For these reasons, we propose to disapprove the contingency measure 
element of the 2018 PM2.5 Plan (and the related contingency 
measure in District Rule 4901) under CAA section 179(c)(9) and 40 CFR 
51.1014 with respect to the Serious area planning requirements for the 
2012 annual PM2.5 NAAQS in the SJV. While the contingency 
measure provision of the 2019 amendment to Rule 4901 has an adequate 
triggering mechanism for failure to attain, we propose to disapprove it 
because it may result in no emissions reductions if the area fails to 
attain the NAAQS by the applicable attainment date. Furthermore, 
because the contingency measure element and the contingency measure of 
Rule 4901 lack any to-be-triggered measure for failure to meet a 
quantitative milestone, failure to submit a quantitative milestone 
report, or failure to meet an RFP requirement, we propose that the 
submissions are also inadequate with respect to the RFP contingency 
measure requirements. Lastly, the contingency measure element, and the 
associated contingency measure in District Rule 4901, fail to provide 
emissions reductions roughly equivalent to one year's worth of progress 
or to provide an adequate reasoned justification why a smaller amount 
of emissions reductions is appropriate.\342\
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    \342\ 81 FR 58010, 58067. We note that the 2018 PM2.5 
Plan includes estimates of surplus emissions reductions from 
already-implemented measures to support approval of the contingency 
measure; however, a recent Ninth Circuit decision rejected reliance 
on surplus emissions reductions from already-implemented measures as 
the basis for approving a contingency measure element that relied on 
a contingency measure that would provide far less than one year's 
worth of progress. See Assoc. of Irritated Residents v. EPA, 10 
F.4th 937 (9th Cir. 2021).
---------------------------------------------------------------------------

    If the EPA finalizes the proposed disapproval of the contingency 
measure element for the 2012 annual PM2.5 NAAQS and 
finalizes approval of the Plan's RFP demonstration, modeled attainment 
demonstration, and motor vehicle emissions budgets, the area would be 
eligible for a protective finding under the transportation conformity 
rule because the 2018 PM2.5 Plan reflects adopted control 
measures and contains enforceable commitments that fully satisfy the 
emissions reductions requirements for RFP and attainment for the 2012 
annual PM2.5 NAAQS.\343\
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    \343\ 40 CFR 93.120(a)(3).
---------------------------------------------------------------------------

I. Motor Vehicle Emission Budgets

1. Requirements for Motor Vehicle Emission Budgets
    Section 176(c) of the CAA requires federally funded or approved 
actions in nonattainment and maintenance areas to conform to the SIP's 
goals of eliminating or reducing the severity and number of violations 
of the NAAQS and achieving expeditious attainment of the standards. 
Conformity to the SIP's goals means that such actions will not: (1) 
Cause or contribute to new 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

[[Page 74348]]

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 (RTP) and 
transportation improvement programs (TIP) conform to the applicable 
SIP. This demonstration is typically done by showing that estimated 
emissions from existing and planned highway and transit systems are 
less than or equal to the motor vehicle emissions budgets (``budgets'') 
contained in all control strategy plans applicable to the area. An 
attainment or maintenance plan for the PM2.5 NAAQS should 
include budgets for the attainment year, each required RFP milestone 
year, or the last year of the maintenance plan, 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 of the motor vehicle control measures contained in the 
attainment and RFP demonstrations.\344\
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    \344\ 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.\345\ For an area designated nonattainment for the 2012 
annual PM2.5 NAAQS, a Serious area attainment plan that 
demonstrates attainment by the end of the 10th calendar year following 
the date of designation must contain quantitative milestones to be 
achieved no later than 7.5 years and 10.5 years after the date the area 
was designated nonattainment.\346\ Given that the SJV was designated 
nonattainment for the 2012 annual PM2.5 NAAQS effective 
April 15, 2015, the required Serious area milestone dates for the SJV 
are October 15, 2022, and October 15, 2025. Given that the 2018 
PM2.5 Plan includes a demonstration of attainment of these 
NAAQS by December 31, 2025, the attainment year and the 2025 milestone 
year coincide.
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    \345\ 40 CFR 51.1012(a), 51.1013(a)(2).
    \346\ 40 CFR 51.1013(a)(2)(i).
---------------------------------------------------------------------------

    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 motor vehicle emissions from tailpipes, brake 
wear, and tire wear. With respect to PM2.5 from re-entrained 
road dust and 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 emissions of these pollutants 
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 pollutants in the 
approved (or adequate) budget as part of the RFP, attainment, or 
maintenance strategy.\347\
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    \347\ 40 CFR 93.102(b)(3), 93.102(b)(2)(v), and 93.122(f); see 
also Conformity Rule preamble at 69 FR 40004, 40031-36 (July 1, 
2004).
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    In addition, transportation conformity requirements apply with 
respect to emissions of NOX unless 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.\348\
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    \348\ 40 CFR 93.102(b)(2)(iv).
---------------------------------------------------------------------------

    It is not always necessary for states to establish motor vehicle 
emissions budgets for all of the 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 that precursor(s) 
consistent with the applicability requirements of the transportation 
conformity regulations (40 CFR 93.102(b)(2)(iv) and (v)).\349\
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    \349\ 81 FR 58010, 58055, 58058, and 58090.
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    Additionally, the transportation conformity regulations contain 
criteria for determining whether emissions of one or more 
PM2.5 precursors are insignificant for transportation 
conformity purposes.\350\ 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.\351\
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    \350\ 40 CFR 93.109(f).
    \351\ 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 emission 
trading between conformity budgets for conformity purposes is described 
in 40 CFR 93.124(c).
    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.\352\ The EPA can notify the public by either posting an 
announcement that the EPA has received SIP budgets on the EPA's 
adequacy website (40 CFR 93.118(f)(1)), or through a Federal Register 
notice of proposed rulemaking when the EPA reviews the adequacy of an 
implementation plan budget simultaneously with its review and action on 
the SIP itself (40 CFR 93.118(f)(2)).
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    \352\ 40 CFR 93.118(f).

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[[Page 74349]]

Summary of State's Submission
    The 2018 PM2.5 Plan includes budgets for direct 
PM2.5 and NOX emissions for the 2019 and 2022 RFP 
milestone years, the projected attainment year (2025), and one post-
attainment year quantitative milestone (2028).\353\ The Plan 
establishes separate direct PM2.5 and NOX subarea 
budgets for each county, or partial county (for Kern County), in the 
SJV.\354\ CARB calculated the budgets using EMFAC2014,\355\ CARB's 
latest version of the EMFAC model for estimating emissions from on-road 
vehicles operating in California that was approved by EPA at the time 
of Plan development, and the latest modeled vehicle miles traveled and 
speed distributions from the SJV MPOs from the Final 2017 Federal 
Transportation Improvement Plans, adopted in September 2016. The 
budgets reflect annual average emissions consistent with the annual 
averaging period of the 2012 annual PM2.5 NAAQS and the 2018 
PM2.5 Plan's RFP demonstration.
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    \353\ 2018 PM2.5 Plan, App. D, Table 3-3.
    \354\ 40 CFR 93.124(c) and (d).
    \355\ 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.
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    The required budget years applicable to the Serious area plan 
portion of the 2018 PM2.5 Plan for the 2012 annual 
PM2.5 NAAQS are 2022 and 2025. In our previous final rule on 
the State's Moderate area plan for the 2012 annual PM2.5 
NAAQS, we approved the budgets for the 2022 RFP milestone year and, 
therefore, will not be acting on them again in this action.\356\ 
However, we include them as a reference point, given our discussion of 
the 2022 year in section IV.G of this proposed rule. Also, while the 
Plan includes budgets for 2019, consistent with our final rule on the 
Moderate area plan, we are not evaluating the 2019 budgets because 
budgets for that year would not be used in any future conformity 
determination because the plan contains budgets for 2022 and other 
years in the future, and because they are not required for the 
submitted Serious area plan.
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    \356\ 86 FR 67343, 67346.
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    Furthermore, the EPA would begin the motor vehicle emissions budget 
adequacy and approval review processes for the 2028 post-attainment 
milestone year budgets only if the area fails to attain the standard by 
December 31, 2025 (the applicable Serious area attainment date if the 
EPA were to finalize approval of the 2018 PM2.5 Plan's 
attainment demonstration). If found adequate or approved, that would 
result in the 2028 budgets being used in future transportation 
conformity determinations in any area that needed additional emissions 
reductions to attain the PM2.5 NAAQS.
    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.\357\ 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 that control of 
these precursors would not significantly contribute to attainment of 
the 2012 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 also included a discussion of 
the significance/insignificance factors for ammonia, SO2, 
and VOC, which would demonstrate a finding of insignificance under the 
transportation conformity rule.\358\ The State is not required to 
include re-entrained road dust in the budgets under section 
93.103(b)(3) 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. The Plan does include a discussion of the significance/
insignificance factors for re-entrained road dust.\359\ The budgets 
included in the 2018 PM2.5 Plan are shown in Table 9 of this 
proposed rule.
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    \357\ 2018 PM2.5 Plan, App. D, D-122 to D-123.
    \358\ 40 CFR 93.109(f).
    \359\ 2018 PM2.5 Plan, App. D, D-121 and D-122.

         Table 9--Motor Vehicle Emission Budgets for the San Joaquin Valley for the 2012 PM2.5 Standard
                                              [Annual average, tpd]
----------------------------------------------------------------------------------------------------------------
                                                        2022 (RFP year) \a\           2025 (attainment year)
                     County                      ---------------------------------------------------------------
                                                       PM2.5            NOX            PM2.5            NOX
----------------------------------------------------------------------------------------------------------------
Fresno..........................................             0.9            21.2             0.8            14.3
Kern............................................             0.8            19.4             0.8            12.8
Kings...........................................             0.2             4.1             0.2             2.7
Madera..........................................             0.2             3.5             0.2             2.3
Merced..........................................             0.3             7.6             0.3             5.0
San Joaquin.....................................             0.6            10.0             0.6             6.9
Stanislaus......................................             0.4             8.1             0.4             5.6
Tulare..........................................             0.4             6.9             0.4             4.7
----------------------------------------------------------------------------------------------------------------
Source: 2018 PM2.5 Plan, Appendix D, Table 3-3. Budgets are rounded to the nearest tenth of a ton.
\a\ The EPA has already approved the 2022 RFP budgets in our final rule on the State's Moderate area plan for
  the 2012 annual PM2.5 NAAQS in the SJV.

    In the submittal letter for the 2018 PM2.5 Plan, CARB 
requested that the EPA limit the duration of the approval of the 
budgets to the period before the effective date of the EPA's adequacy 
finding for any subsequently submitted budgets.\360\
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    \360\ Letter dated May 9, 2019, from Richard W. Corey, Executive 
Officer, CARB to Mike Stoker, Regional Administrator, EPA Region IX, 
3.
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    The 2018 PM2.5 Plan also includes a proposed trading 
mechanism for transportation conformity analyses that would allow 
future decreases in NOX emissions from on-road mobile 
sources to offset any on-road increases in direct PM2.5 
emissions. In the 2018 PM2.5 Plan, the approximate weighting 
ratios of the precursor emissions for annual average PM2.5 
formation in equivalent tons per

[[Page 74350]]

day of NOX are: 6.5:1 (i.e., reducing 6.5 tons of 
NOX is equivalent to reducing one ton of PM2.5). 
The ratio is based on a sensitivity analysis based on a 30% reduction 
of NOX or PM2.5 emissions and the corresponding 
impact on design values at sites in Bakersfield and Fresno.
    To ensure that the trading mechanism does not affect the ability of 
the SJV 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.\361\ The Plan also provides that the SJV 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.
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    \361\ 2018 PM2.5 Plan, App. D, D-126 and D-127.
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EPA Evaluation and Proposed Action
    The EPA generally first conducts a preliminary review of budgets 
submitted with an attainment or maintenance plan for PM2.5 
for adequacy, prior to taking action on the plan itself, and did so 
with respect to the PM2.5 budgets in the 2018 
PM2.5 Plan. On June 18, 2019, the EPA announced the 
availability of the 2018 PM2.5 Plan 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 July 18, 
2019. We did not receive any comments during this comment period.
    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 2012 annual 
PM2.5 NAAQS in the SJV, as discussed in section IV.B of this 
preamble, 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 2012 annual PM2.5 NAAQS in the SJV.\362\ Based on 
the information about re-entrained road dust in the Plan and in 
accordance with 40 CFR 93.102(b)(3), the EPA proposes to find that it 
is not necessary to include re-entrained road dust emissions in the 
budgets for 2012 annual PM2.5 NAAQS in the SJV.
---------------------------------------------------------------------------

    \362\ 40 CFR 93.102(b)(2)(v).
---------------------------------------------------------------------------

    For the reasons discussed in sections IV.G and IV.F of this 
proposed rule, the EPA is proposing to approve the RFP and attainment 
demonstrations, respectively, in the 2018 PM2.5 Plan. The 
2025 budgets for RFP and attainment, as shown in Table 9 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 2025 budgets listed in Table 9. We provide a more detailed 
discussion in section VI of the EPA's 2012 Annual PM2.5 TSD.
    As discussed in section IV.I.2 of this proposed rule, we have 
already approved the 2022 RFP budgets for the SJV as part of our final 
rule on the State's Moderate area plan for the 2012 annual 
PM2.5 NAAQS, as supplemented by the 2018 PM2.5 
Plan. The budgets that the EPA is proposing to approve relate to the 
2012 annual PM2.5 NAAQS only, and our proposed approval does 
not affect the status of the previously-approved budgets for the 1997 
PM2.5 NAAQS and related trading mechanism, which remain in 
effect for that PM2.5 NAAQS, nor the 2006 24-hour 
PM2.5 NAAQS and related trading mechanism, which remain in 
effect for that PM2.5 NAAQS.\363\
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    \363\ 76 FR 69896, 69923-69924 (final rule approving direct 
PM2.5 and NOX budgets for 2012 and 2014 for 
the 1997 annual and 24-hour PM2.5 NAAQS); and 85 FR 
44192, 44204 (final rule approving direct PM2.5 and 
NOX budgets for 2020, 2023, and 2024 for the 2006 24-hour 
PM2.5 NAAQS). The EPA has also proposed to approve 
budgets from the 2018 PM2.5 Plan for direct 
PM2.5 and NOX for 2017 and 2020 for the 1997 
24-hour PM2.5 NAAQS. 86 FR 53150, 53176-53179.
---------------------------------------------------------------------------

    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 2018 PM2.5 Plan, as allowed for 
under 40 CFR 93.124(b). This trading mechanism would allow future 
decreases in NOX emissions from on-road mobile sources to 
offset any on-road increases in PM2.5, using a 6.5:1 
NOX:PM2.5 ratio. To ensure that the trading 
mechanism does not affect the ability to meet the NOX 
budget, the Plan provides that the NOX emission reductions 
available to supplement the PM2.5 budget would only be those 
remaining after the NOX budget has been met. The SJV 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 through D-127 in Appendix D of the 2018 PM2.5 Plan and 
concludes that it is appropriate for transportation conformity purposes 
in the SJV for the 2012 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 \364\ and the 2012 PM2.5 Plan for the 
2006 24-hour PM2.5 NAAQS.\365\ 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 reductions, and to express the ratio of these modeled 
sensitivities as an inter-pollutant trading ratio.
---------------------------------------------------------------------------

    \364\ 80 FR 1816, 1841 (January 13, 2015) (noting the EPA's 
prior approval of motor vehicle emissions budgets for the 1997 
annual and 24-hour PM2.5 standards in the 2008 
PM2.5 Plan at 76 FR 69896).
    \365\ 81 FR 59876 (August 31, 2016).
---------------------------------------------------------------------------

    In the updated analysis for the 2018 PM2.5 Plan, the 
State completed separate sensitivity analyses for the annual and 24-
hour standards 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 SJV 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:PM2.5 ratios that range 
from a high of 7.1 at the Bakersfield-California Avenue monitor to a 
low of 6.0 at the two Fresno monitors.\366\ We consider that the 
State's approach is a reasonable method to use to develop ratios for 
transportation conformity purposes. We therefore propose to approve the 
6.5:1 NOX for PM2.5 trading mechanism as 
enforceable components of the transportation conformity program for the 
SJV for the 2012 annual PM2.5 NAAQS.
---------------------------------------------------------------------------

    \366\ 2018 PM2.5 Plan, App. D, D-126.
---------------------------------------------------------------------------

    Under the transportation conformity rule, once budgets are 
approved, they cannot be superseded by revised budgets submitted for 
the same CAA purpose and the same year(s) addressed by the previously 
approved SIP until the EPA approves the revised budgets as a SIP 
revision. As a general matter, such approved budgets cannot be 
superseded

[[Page 74351]]

by revised budgets found adequate, but rather only through approval of 
the revised budgets, unless the EPA specifies otherwise in its approval 
of a SIP by limiting the duration of the approval to last only until 
subsequently submitted budgets are found adequate.\367\
---------------------------------------------------------------------------

    \367\ 40 CFR 93.118(e)(1).
---------------------------------------------------------------------------

    In the submittal letter for the 2018 PM2.5 Plan, CARB 
requested that we limit the duration of our approval of the budgets to 
the period before the effective date of the EPA's adequacy finding for 
any subsequently submitted budgets.\368\ However, CARB recently 
clarified that since they have submitted EMFAC2021 for EPA review, they 
no longer request that we limit the duration of our approval.\369\
---------------------------------------------------------------------------

    \368\ Letter dated May 9, 2019, from Richard W. Corey, Executive 
Officer, CARB, to Mike Stoker, Regional Administrator, EPA Region 
IX, 3.
    \369\ Email dated November 30, 2021, from Nesamani Kalandiyur, 
Manager, Transportation Analysis Section, Sustainable Transportation 
and Communities Division, CARB, to Karina O'Connor, Air Planning 
Office, EPA Region IX.
---------------------------------------------------------------------------

    Lastly, in section IV.H of this proposed rule, the EPA is proposing 
to disapprove the contingency measure element of the 2018 
PM2.5 Plan with respect to the Serious area requirements for 
the 2012 annual PM2.5 NAAQS. If the EPA were to finalize the 
proposed disapproval of the 2012 annual PM2.5 NAAQS Serious 
area contingency measure element, the area would be eligible for a 
protective finding under the transportation conformity rule because the 
2018 PM2.5 Plan reflects adopted control measures that fully 
satisfy the emissions reductions requirements for the RFP and 
attainment year of 2025.\370\
---------------------------------------------------------------------------

    \370\ 40 CFR 93.120(a)(3).
---------------------------------------------------------------------------

Summary of Proposed Actions and Request for Public Comment

    For the reasons discussed in this proposed rule, under CAA section 
110(k)(3), the EPA proposes to approve, as a revision to the California 
SIP, the following portions of the SJV PM2.5 Plan for the 
2012 annual PM2.5 NAAQS to address the CAA's Serious area 
planning requirements in the SJV nonattainment area:
    1. The 2013 base year emission inventories (CAA section 172(c)(3) 
and 40 CFR 51.1008(b));
    2. the demonstration that BACM, including BACT, for the control of 
direct PM2.5 and PM2.5 plan precursors will be 
implemented no later than 4 years after the area was reclassified (CAA 
section 189(b)(1)(B) and 40 CFR 51.1010(a));
    3. the demonstration (including air quality modeling) that the Plan 
provides for attainment as expeditiously as practicable but no later 
than December 31, 2025 (CAA sections 189(b)(1)(A) and 40 CFR 
51.1011(b));
    4. plan provisions that require RFP toward attainment by the 
applicable date (CAA section 172(c)(2) and 40 CFR 51.1012(a));
    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 attainment date (CAA section 
189(c) and 40 CFR 51.1013(a)(2)(i));
    6. motor vehicle emissions budgets for 2025 as shown in Table 9 of 
this proposed rule (CAA section 176(c) and 40 CFR part 93, subpart A); 
and
    7. the inter-pollutant trading mechanism provided for use in 
transportation conformity analyses for the 2012 annual PM2.5 
NAAQS, in accordance with 40 CFR 93.124(b).
    We may, however, reconsider this proposal if, based on new 
information or public comments, we find that the State has not 
satisfied the statutory criteria for Serious area PM2.5 
plans.
    Pursuant to CAA section 110(k)(3), the EPA proposes to disapprove 
the contingency measure element of the 2018 PM2.5 Plan for 
the 2012 annual PM2.5 NAAQS, as implemented by section 5.7.3 
of District Rule 4901, under CAA section 179(c)(9) and 40 CFR 51.1014. 
Among other reasons, the element includes no specific measures to be 
undertaken if the state fails to submit a quantitative milestone report 
for the area, or if the area fails to meet RFP or a quantitative 
milestone. In addition, the element includes a specific measure 
(section 5.7.3 of District Rule 4901) that may not result in any 
emissions reductions following a failure to attain the 2012 annual 
PM2.5 NAAQS by the applicable attainment date under certain 
circumstances.
    If we finalize the disapproval of the contingency measure element 
as proposed, the offset sanction in CAA section 179(b)(2) would apply 
in the SJV 18 months after the effective date of a final disapproval, 
and the highway funding sanctions in CAA section 179(b)(1) would apply 
in the area six months after the offset sanction is imposed.\371\ 
Neither sanction will be imposed under the CAA if the State submits and 
we approve, prior to the implementation of the sanctions, a SIP 
revision that corrects the deficiencies that we identify in our final 
action. The EPA intends to work with CARB and the SJVUAPCD to correct 
the deficiencies in a timely manner.
---------------------------------------------------------------------------

    \371\ 40 CFR 52.31.
---------------------------------------------------------------------------

    In addition to the sanctions, CAA section 110(c)(1) provides that 
the EPA must promulgate a federal implementation plan (FIP) addressing 
any disapproved elements of an attainment plan two years after the 
effective date of disapproval unless the State submits, and the EPA 
approves, a SIP submission that cures the disapproved elements.
    Also, we previously approved the Serious area plan RFP and 
attainment demonstrations and the motor vehicle emissions budgets for 
the 2006 24-hour PM2.5 NAAQS \372\ and the Moderate area 
plan RACM, additional reasonable measures, and RFP demonstrations.\373\ 
In this proposed rule, we are proposing to approve the Serious area 
plan BACM/BACT, RFP, and attainment demonstrations, and motor vehicle 
emission budgets for the 2012 annual PM2.5 NAAQS. Because of 
those actions, we are proposing to issue a protective finding under 40 
CFR 93.120(a)(3) to the disapproval of the contingency measure element.
---------------------------------------------------------------------------

    \372\ 85 FR 44192.
    \373\ 86 FR 67343, 67346.
---------------------------------------------------------------------------

    Without a protective finding, the final disapprovals would result 
in a conformity freeze, under which only projects in the first four 
years of the most recent conforming Regional Transportation Plans 
(RTPs) and Transportation Improvement Programs (TIPs) can proceed. 
Generally, during a freeze, no new RTPs, TIPs, or RTP/TIP amendments 
can be found to conform until another control strategy implementation 
plan revision fulfilling the same CAA requirements is submitted, the 
EPA finds its motor vehicle emissions budget(s) adequate pursuant to 
Sec.  93.118 or approves the submission, and conformity to the 
implementation plan revision is determined.\374\ Under a protective 
finding, the final disapproval of the contingency measures elements 
would not result in a transportation conformity freeze in the SJV 
PM2.5 nonattainment area and the MPOs may continue to make 
transportation conformity determinations.
---------------------------------------------------------------------------

    \374\ 40 CFR 93.120(a)(2).
---------------------------------------------------------------------------

    We will accept comments from the public on these proposals for the 
next 30 days. The deadline and instructions for submission of comments 
are provided in the DATES and ADDRESSES sections at the beginning of 
this proposed rule.

[[Page 74352]]

VI. Statutory and Executive Order Reviews

    Additional information about these statutes and Executive Orders 
can be found at https://www.epa.gov/laws-regulations/laws-and-executive-orders.

A. Executive Order 12866: Regulatory Planning and Review and Executive 
Order 13563: Improving Regulation and Regulatory Review

    This action is not a significant regulatory action and was 
therefore not submitted to the Office of Management and Budget (OMB) 
for review.

B. Paperwork Reduction Act (PRA)

    This action does not impose an information collection burden under 
the PRA because this action does not impose additional requirements 
beyond those imposed by state law.

C. Regulatory Flexibility Act (RFA)

    I certify that this action will not have a significant economic 
impact on a substantial number of small entities under the RFA. This 
action will not impose any requirements on small entities beyond those 
imposed by state law.

D. Unfunded Mandates Reform Act (UMRA)

    This action does not contain any unfunded mandate as described in 
UMRA, 2 U.S.C. 1531-1538, and does not significantly or uniquely affect 
small governments. This action does not impose additional requirements 
beyond those imposed by state law. Accordingly, no additional costs to 
state, local, or tribal governments, or to the private sector, will 
result from this action.

E. Executive Order 13132: Federalism

    This action does not have federalism implications. It will not have 
substantial direct effects on the states, on the relationship between 
the national government and the states, or on the distribution of power 
and responsibilities among the various levels of government.

F. Executive Order 13175: Coordination With Indian Tribal Governments

    This action does not have tribal implications, as specified in 
Executive Order 13175, because 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, and will not 
impose substantial direct costs on tribal governments or preempt tribal 
law. Thus, Executive Order 13175 does not apply to this action.

G. Executive Order 13045: Protection of Children From Environmental 
Health Risks and Safety Risks

    The EPA interprets Executive Order 13045 as applying only to those 
regulatory actions that concern environmental health or safety risks 
that the EPA has reason to believe may disproportionately affect 
children, per the definition of ``covered regulatory action'' in 
section 2-202 of the Executive Order. This action is not subject to 
Executive Order 13045 because it does not impose additional 
requirements beyond those imposed by state law.

H. Executive Order 13211: Actions That Significantly Affect Energy 
Supply, Distribution, or Use

    This action is not subject to Executive Order 13211, because it is 
not a significant regulatory action under Executive Order 12866.

I. National Technology Transfer and Advancement Act (NTTAA)

    Section 12(d) of the NTTAA directs the EPA to use voluntary 
consensus standards in its regulatory activities unless to do so would 
be inconsistent with applicable law or otherwise impractical. The EPA 
believes that this action is not subject to the requirements of section 
12(d) of the NTTAA because application of those requirements would be 
inconsistent with the CAA.

J. Executive Order 12898: Federal Actions To Address Environmental 
Justice in Minority Populations and Low-Income Population

    The EPA lacks the discretionary authority to address environmental 
justice in this rulemaking.

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: December 16, 2021.
Deborah Jordan,
Acting Regional Administrator, Region IX.
[FR Doc. 2021-27796 Filed 12-28-21; 8:45 am]
BILLING CODE 6560-50-P