[Federal Register Volume 86, Number 167 (Wednesday, September 1, 2021)]
[Proposed Rules]
[Pages 49100-49137]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-18764]



[[Page 49099]]

Vol. 86

Wednesday,

No. 167

September 1, 2021

Part II





Environmental Protection Agency





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40 CFR Parts 52 and 81





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Clean Air Plans; California; San Joaquin Valley Moderate Area Plan and 
Reclassification as Serious Nonattainment for the 2012 PM2.5 NAAQS; 
Contingency Measures for the 2006 PM2.5 NAAQS; Proposed Rules

Federal Register / Vol. 86, No. 167 / Wednesday, September 1, 2021 / 
Proposed Rules

[[Page 49100]]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 52 and 81

[EPA-R09-OAR-2021-0543; FRL-8846-01-R9]


Clean Air Plans; California; San Joaquin Valley Moderate Area 
Plan and Reclassification as Serious Nonattainment for the 2012 PM2.5 
NAAQS; Contingency Measures for the 2006 PM2.5 NAAQS

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) proposes to take 
action on portions of four state implementation plan (SIP) revisions 
submitted by California to address Clean Air Act (CAA or ``Act'') 
requirements for the 2012 fine particulate matter (PM<INF>2.5</INF>) 
national ambient air quality standards (NAAQS or ``standards'') and for 
the 2006 PM<INF>2.5</INF> NAAQS in the San Joaquin Valley (SJV) 
PM<INF>2.5</INF> nonattainment area. Specifically, the EPA proposes to 
approve all but the contingency measure element of the submitted 
Moderate area plan for the 2012 PM<INF>2.5</INF> NAAQS, as updated by 
the submitted Serious area plan and related Valley State SIP Strategy, 
as meeting all applicable Moderate area plan requirements for the 2012 
PM<INF>2.5</INF> NAAQS and to approve 2022 motor vehicle emissions 
budgets for use in transportation conformity analyses for the 2012 
PM<INF>2.5</INF> NAAQS. The EPA proposes to disapprove the contingency 
measure element with respect to the ``Moderate'' area requirements for 
the 2012 PM<INF>2.5</INF> NAAQS. The EPA also proposes to reclassify 
the SJV PM<INF>2.5</INF> nonattainment area, including reservation 
areas of Indian country and any other area of Indian country within it 
where the EPA or a tribe has demonstrated that the tribe has 
jurisdiction, as a ``Serious'' nonattainment area for the 2012 
PM<INF>2.5</INF> NAAQS based on the EPA's determination that the area 
cannot practicably attain the standard by the applicable Moderate area 
attainment date of December 31, 2021. Upon final reclassification of 
the SJV as a Serious area for this NAAQS, California would be required 
to submit a Serious area plan for the area that includes a 
demonstration of attainment by the applicable Serious area attainment 
date, which is no later than December 31, 2025, or by the most 
expeditious alternative date practicable. However, we note that 
California has already submitted such Serious area plan that the EPA 
will address in a separate rulemaking. Lastly, the EPA is proposing to 
disapprove the contingency measure element in the Serious area plan for 
the 2006 PM<INF>2.5</INF> NAAQS.

DATES: Any comments on this proposal must be received by October 1, 
2021.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R09-
OAR-2021-0543 at https://www.regulations.gov, or via email to 
<a href="/cdn-cgi/l/email-protection#a1ccc0d8d28fd3ced3d8e1c4d1c08fc6ced7"><span class="__cf_email__" data-cfemail="dbb6baa2a8f5a9b4a9a29bbeabbaf5bcb4ad">[email protected]</span></a>. For comments submitted at Regulations.gov, follow 
the online instructions for submitting comments. Once submitted, 
comments cannot be edited or removed from Regulations.gov. For either 
manner of submission, the EPA may publish any comment received to its 
public docket. Do not submit electronically any information you 
consider to be Confidential Business Information (CBI) or other 
information whose disclosure is restricted by statute. Multimedia 
submissions (e.g., audio or video) must be accompanied by a written 
comment. The written comment is considered the official comment and 
should include discussion of all points you wish to make. The EPA will 
generally not consider comments or comment contents located outside of 
the primary submission (i.e., on the web, cloud, or other file sharing 
system). For additional submission methods, please contact the person 
identified in the FOR FURTHER INFORMATION CONTACT section. For the full 
EPA public comment policy, information about CBI or multimedia 
submissions, and general guidance on making effective comments, please 
visit https://www.epa.gov/dockets/commenting-epa-dockets. If you need 
assistance in a language other than English or if you are a person with 
disabilities who needs a reasonable accommodation at no cost to you, 
please contact the person identified in the FOR FURTHER INFORMATION 
CONTACT section.

FOR FURTHER INFORMATION CONTACT: Rory Mays, Air Planning Office (AIR-
2), EPA Region IX, by phone at (415) 972-3227 or email at 
<a href="/cdn-cgi/l/email-protection#513c3028227f233e2328113421307f363e27"><span class="__cf_email__" data-cfemail="f69b978f85d88499848fb6938697d8919980">[email protected]</span></a>.

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

Table of Contents

I. Background for Proposed Action
II. Summary of San Joaquin Valley 2016 and 2018 PM<INF>2.5</INF> 
Plans
    A. 2016 PM<INF>2.5</INF> Plan Summary
    B. 2018 PM<INF>2.5</INF> Plan Summary
    C. Procedural Requirements for SIPs and SIP Revisions
III. Clean Air Act Requirements for Moderate PM<INF>2.5</INF> 
Nonattainment Area Plans
IV. Review of San Joaquin Valley Plans for Moderate Area 
Requirements
    A. Emissions Inventory
    B. PM<INF>2.5</INF> Precursors
    C. Air Quality Modeling
    D. Reasonably Available Control Measures and Control Strategy
    E. Nonattainment New Source Review Requirements Under CAA 
Section 189(e)
    F. Demonstration That Attainment by Moderate Area Attainment 
Date Is Impracticable
    G. Reasonable Further Progress and Quantitative Milestones
    H. Contingency Measures
    I. Motor Vehicle Emissions Budgets
V. Reclassification as Serious Nonattainment and Serious Area SIP 
Requirements
    A. Reclassification as Serious and Applicable Attainment Date
    B. Clean Air Act Requirements for Serious Area Plans
    C. Statutory Deadline for Submission of Serious Area Plan
VI. Reclassification of Areas of Indian Country
VII. Review of Contingency Measure Element for the 2006 
PM<INF>2.5</INF> NAAQS
    A. Requirements for Contingency Measures
    B. Summary of State's Contingency Measure Element for 2006 
PM<INF>2.5</INF> NAAQS
    C. EPA Evaluation and Proposed Action
VIII. Summary of Proposed Actions and Request for Public Comment
IX. 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 
(PM<INF>2.5</INF>) by lowering the level from 15.0 micrograms per cubic 
meter ([micro]g/m\3\) to 12.0 [micro]g/m\3\ (``2012 PM<INF>2.5</INF> 
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 
PM<INF>2.5</INF> concentrations above these levels.
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    \1\ 78 FR 3086 and 40 CFR 50.18. The EPA first established NAAQS 
for PM<INF>2.5</INF> 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 PM<INF>2.5</INF> NAAQS''). In 
addition, on October 17, 2006, the EPA strengthened the 24-hour 
(daily) NAAQS for PM<INF>2.5</INF> by lowering the level from 65 
[micro]g/m\3\ to 35 [micro]g/m\3\ (``2006 PM<INF>2.5</INF> NAAQS''). 
71 FR 61144 and 40 CFR 50.13. Unless otherwise noted, all references 
to the PM<INF>2.5</INF> standards in this notice are to the 2012 
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 PM<INF>2.5</INF> levels and premature 
mortality. Other important health effects associated with 
PM<INF>2.5</INF> exposure include aggravation of respiratory and 
cardiovascular disease (as indicated by increased hospital admissions, 
emergency room visits,

[[Page 49101]]

absences from school or work, and restricted activity days), changes in 
lung function, and increased respiratory symptoms. Individuals 
particularly sensitive to PM<INF>2.5</INF> exposure include older 
adults, people with heart and lung disease, and children.\2\ 
PM<INF>2.5</INF> can be emitted directly into the atmosphere as a solid 
or liquid particle (``primary PM<INF>2.5</INF>'' or ``direct 
PM<INF>2.5</INF>'') or can be formed in the atmosphere (``secondary 
PM<INF>2.5</INF>'') as a result of various chemical reactions among 
precursor pollutants such as nitrogen oxides (NO<INF>X</INF>), sulfur 
oxides (SO<INF>X</INF>), volatile organic compounds (VOC), and ammonia 
(NH<INF>3</INF>).\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. Under subpart 4 of part D of 
title I of the CAA and applicable implementing regulations, the EPA 
designates areas found to be violating the PM<INF>2.5</INF> NAAQS, and 
areas with emissions that contribute to such violations, as 
nonattainment and classifies them initially as Moderate.\4\ States with 
Moderate areas have to attain the NAAQS as expeditiously as 
practicable, but not later than the end of the sixth calendar year 
after the date of designation.\5\ The EPA reclassifies as Serious those 
Moderate areas that cannot practicably attain the NAAQS by the latest 
statutory attainment date and those areas that fail to attain the NAAQS 
by the applicable attainment date. States with Serious areas are 
subject to more stringent SIP revision requirements and must attain the 
NAAQS as expeditiously as practicable, but not later than the end of 
the tenth calendar year after designation.
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    \4\ CAA section 188(a) and 40 CFR 51.1002(a).
    \5\ CAA section 188(c)(1) and 40 CFR 51.1004(a)(1)(i).
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    On January 15, 2015, the EPA designated and classified the SJV as 
Moderate nonattainment for the 2012 PM<INF>2.5</INF> NAAQS.\6\ With 
respect to the 1997 PM<INF>2.5</INF> NAAQS and the 2006 
PM<INF>2.5</INF> NAAQS, the SJV is designated nonattainment and is 
classified as Serious.\7\ The SJV PM<INF>2.5</INF> 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.\8\ 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. Under State law, the San Joaquin Valley Unified Air Pollution 
Control District (SJVUAPCD or ``District'') has primary responsibility 
for developing plans to provide for attainment of the NAAQS in this 
area. The District works cooperatively with the California Air 
Resources Board (CARB) in preparing these 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 and some categories of consumer products.
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    \6\ 80 FR 2206 (codified at 40 CFR 81.305).
    \7\ See the tables of area designations for the 1997 and 2006 
PM<INF>2.5</INF> NAAQS in 40 CFR 81.305.
    \8\ For a precise description of the geographic boundaries of 
the SJV PM<INF>2.5</INF> nonattainment area, see 40 CFR 81.305.
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    States with areas designated as nonattainment are required to 
submit SIP revisions that address various requirements, including the 
requirement to demonstrate attainment of the NAAQS as expeditiously as 
practicable but no later than the maximum attainment date established 
in the CAA or EPA's implementing regulations. However, states with 
Moderate PM<INF>2.5</INF> nonattainment areas may submit an 
impracticability demonstration, in lieu of a modeled attainment 
demonstration, if the state can establish that the area cannot 
practicably attain a particular PM<INF>2.5</INF> NAAQS by the outermost 
statutory Moderate area attainment date.\9\
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    \9\ 40 CFR 51.1002(b)(1).
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    On May 10, 2019, CARB made two SIP submissions intended to address 
the attainment plan requirements for areas designated as nonattainment 
for the 2012 PM<INF>2.5</INF> NAAQS.\10\ First, the ``2016 Moderate 
Area Plan for the 2012 PM<INF>2.5</INF> Standard'' (``2016 
PM<INF>2.5</INF> Plan'') addresses the Moderate area attainment plan 
requirements and includes a demonstration of impracticability of 
attaining the 2012 PM<INF>2.5</INF> NAAQS in the SJV by the latest 
permissible Moderate area attainment date of December 31, 2021. In this 
document, the EPA is proposing action on all portions of the 2016 
PM<INF>2.5</INF> Plan. Second, the ``2018 Plan for the 1997, 2006, and 
2012 PM<INF>2.5</INF> Standards'' (``2018 PM<INF>2.5</INF> Plan'') 
addresses the Serious area attainment plan requirements for the 2012 
PM<INF>2.5</INF> NAAQS, in anticipation of the reclassification of SJV 
from Moderate to Serious for that PM<INF>2.5</INF> NAAQS. The 2018 
PM<INF>2.5</INF> Plan incorporates by reference the ``San Joaquin 
Valley Supplement to the 2016 State Strategy for the State 
Implementation Plan'' (``Valley State SIP Strategy''), a related plan 
adopted by CARB on October 25, 2018, and submitted to the EPA with the 
2018 PM<INF>2.5</INF> Plan on May 10, 2019. For the purposes of this 
action, the relevant portion of the Valley State SIP Strategy includes 
the control measure commitments associated with the quantitative 
milestones for 2019 and 2022.
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    \10\ CARB submitted the two plans electronically on May 10, 
2019, as an attachment to a letter dated May 9, 2019, from Richard 
W. Corey, Executive Officer, CARB, to Mike Stoker, Regional 
Administrator, EPA Region IX.
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    The 2018 PM<INF>2.5</INF> Plan updates several elements in the 2016 
PM<INF>2.5</INF> Plan, including the base year emissions inventory, 
plan precursor demonstration, controls analysis, reasonable further 
progress (RFP) and quantitative milestones, and motor vehicle emission 
budgets (MVEBs or ``budgets''). In this document, the EPA is proposing 
action on those portions of the 2018 PM<INF>2.5</INF> Plan that apply 
to the Moderate area plan requirements for the 2012 PM<INF>2.5</INF> 
NAAQS. However, the EPA is not, at this time, proposing to act on those 
portions of the 2018 PM<INF>2.5</INF> Plan that are not relevant to our 
evaluation of compliance with Moderate area plan requirements for 2012 
PM<INF>2.5</INF> NAAQS, such as the best available control measures 
(BACM) demonstration, control strategy commitments, attainment 
demonstration, RFP demonstration and quantitative milestones for later 
years, and MVEBs for later years.
    The 2018 PM<INF>2.5</INF> Plan also addresses attainment plan 
requirements for areas classified as Serious for the 2006 
PM<INF>2.5</INF> NAAQS. In 2020, we approved those portions of the 2018 
PM<INF>2.5</INF> Plan that pertain to the 2006 PM<INF>2.5</INF> NAAQS, 
excluding the contingency measures element for the 2006 
PM<INF>2.5</INF> NAAQS.\11\ In this document, we are proposing action 
on the portion of the 2018 PM<INF>2.5</INF> Plan that addresses the 
contingency measure requirement for the 2006 PM<INF>2.5</INF> NAAQS.
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    \11\ 85 FR 44192 (July 22, 2020).
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    Lastly, the 2018 PM<INF>2.5</INF> Plan addresses the contingency 
measure requirement for the 2006 PM<INF>2.5</INF> NAAQS by reference 
to, among other things, a District contingency measure, and emissions 
estimates for the year following the attainment year for use in 
evaluating whether the emissions reductions from the contingency 
measure are

[[Page 49102]]

sufficient.\12\ With respect to the District contingency measure, the 
2018 PM<INF>2.5</INF> Plan calls for the District to amend District 
Rule 4901 (``Wood Burning Fireplaces and Wood Burning Heaters'') to 
include a requirement in the rule with a trigger that would activate 
the requirement should the EPA issue a final rulemaking that SJV failed 
to meet a regulatory requirement necessitating implementation of a 
contingency measure.
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    \12\ 2018 PM<INF>2.5</INF> 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 PM<INF>2.5</INF> 
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 a contingency measure. On July 19, 2019, CARB submitted 
the amended rule to the EPA for approval.\13\ We have already taken 
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.\14\ 
Rather, we approved the new provision (section 5.7.3) into the SIP as 
part of our approval of the entire amended rule 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. 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 2016 PM<INF>2.5</INF> Plan for the 2012 PM<INF>2.5</INF> 
NAAQS and the contingency measure element in the 2018 PM<INF>2.5</INF> 
Plan for the 2006 PM<INF>2.5</INF> NAAQS.
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    \13\ Letter dated July 19, 2019, from Richard W. Corey, 
Executive Officer, CARB, to Mike Stoker, Regional Administrator, EPA 
Region IX.
    \14\ 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).
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II. Summary of San Joaquin Valley 2016 and 2018 PM<INF>2.5</INF> Plans

A. 2016 PM2.5 Plan Summary

    The SJVUAPCD Governing Board adopted the 2016 PM<INF>2.5</INF> Plan 
on September 15, 2016, and CARB adopted the plan on January 24, 
2019.\15\ CARB submitted the plan to the EPA on May 10, 2019.
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    \15\ SJVUAPCD Governing Board Resolution 16-9-10, September 15, 
2016, and CARB Resolution 19-1, January 24, 2019.
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    The 2016 PM<INF>2.5</INF> Plan is organized into three chapters, 
five appendices, and two attachments. Chapter 1 (``Introduction'') 
provides general background, including discussion of the federal 
PM<INF>2.5</INF> standards, PM<INF>2.5</INF> pollution and health 
effects in the SJV, challenges to attaining the standards, and the 
District's public process. Chapter 2 (``Impracticability Demonstration 
and Request for Reclassification'') presents CARB and the District's 
demonstration, based on air quality modeling, that attaining the 2012 
PM<INF>2.5</INF> NAAQS by the latest permissible attainment date of 
December 31, 2021, is impracticable, and a request for reclassification 
to Serious. Chapter 3 (``Demonstration of Federal Clean Air Act 
Requirements'') describes how the 2016 PM<INF>2.5</INF> Plan addresses 
the federal requirements for Moderate PM<INF>2.5</INF> nonattainment 
areas, including a plan precursor demonstration, reasonably available 
control measures, RFP, quantitative milestones, contingency measures, 
stationary source permitting, and transportation conformity. The 2016 
PM<INF>2.5</INF> Plan includes the following five technical appendices:
    <bullet> Appendix A (``Air Quality Modeling'') provides the State's 
photochemical air quality modeling in support of the plan's 
impracticability demonstration and precursor demonstration;
    <bullet> Appendix B (``Emissions Inventory'') presents the base 
year and future year emissions inventory for direct PM<INF>2.5</INF>, 
NO<INF>X</INF>, ammonia, SO<INF>X</INF>, and VOC;
    <bullet> Appendix C (``SIP Creditable Incentive-Based Emission 
Reductions'') provides a demonstration of NO<INF>X</INF> emission 
reductions from heavy-duty off-road vehicle engine vehicle replacements 
under the 2011 Carl Moyer Guidelines in support of the plan's Moderate 
contingency measure element;
    <bullet> Appendix D (``New Source Review and Emission Reduction 
Credits'') discusses the use of emission reduction credits (ERCs) in 
the context of the plan; and
    <bullet> Appendix E (``Summary of Significant Comments and 
Responses'') summarizes significant comments received during the 
District's 2016 public review period and the District's responses 
thereto.
    In addition, the 2016 PM<INF>2.5</INF> Plan includes Attachment 1 
(``Stationary and Area Source Control Measure Analyses'') and 
Attachment 2 (``Mobile Source Control Measure Analyses''), which 
together resubmit the State's 2015 analyses that the District's 
stationary and area source control measures and CARB's mobile source 
control measures represent BACM and most stringent measures (MSM).
    Lastly, on December 13, 2019, CARB submitted the following two 
additional documents that CARB had prepared for the 2016 
PM<INF>2.5</INF> Plan and made available for public review along with 
the plan, but had inadvertently omitted them from the May 10, 2019 SIP 
submission to the EPA: \16\ (i) The ``Staff Report, ARB Review of the 
San Joaquin Valley 2016 Moderate Area Plan for the 2012 
PM<INF>2.5</INF> Standard,'' released September 16, 2016 (``CARB 2016 
Staff Report''), that provides CARB's staff review of the 2016 
PM<INF>2.5</INF> Plan, including brief summaries for each of the 
Moderate area plan requirements; and (ii) the ``Modeling Emission 
Inventory for the PM<INF>2.5</INF> State Implementation Plan in the San 
Joaquin Valley,'' August 23, 2016 (``2016 Modeling Emissions 
Inventory'') that describes the development of the 2016 
PM<INF>2.5</INF> Plan's modeling emissions inventory, estimation of the 
2013 base year emissions inventory, the methodology used to develop the 
base year and baseline emissions inventory, and quality assurance of 
the modeling emissions inventory.
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    \16\ Letter dated December 11, 2019, from Richard W. Corey, 
Executive Officer, CARB, to Mike Stoker, Regional Administrator, EPA 
Region IX, with enclosures.
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B. 2018 PM2.5 Plan Summary

    The SJVUAPCD Governing Board adopted the 2018 PM<INF>2.5</INF> Plan 
on November 15, 2018, and CARB adopted the plan on January 24, 
2019.\17\ CARB submitted the 2018 PM<INF>2.5</INF> Plan to the EPA on 
May 10, 2019, concurrently with the 2016 PM<INF>2.5</INF> Plan.
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    \17\ SJVUAPCD Governing Board Resolution 18-11-16, November 15, 
2018, and CARB Resolution 19-1, January 24, 2019.
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    The following portions of the 2018 PM<INF>2.5</INF> Plan and 
related support documents apply to the Moderate area attainment plan 
requirements for the 2012 PM<INF>2.5</INF> NAAQS in the SJV: (i) 
Chapter 4 (``Attainment Strategy for PM<INF>2.5</INF>''); (ii) Chapter 
7 (``Demonstration of Federal Requirements for the 2012 
PM<INF>2.5</INF> Standard''); \18\ (iii) numerous

[[Page 49103]]

appendices to the 2018 PM<INF>2.5</INF> Plan; (iv) CARB's ``Staff 
Report, Review of the San Joaquin Valley 2018 Plan for the 1997, 2006, 
and 2012 PM<INF>2.5</INF> Standards,'' release date December 21, 2018 
(``CARB 2018 Staff Report''); \19\ and (v) the State's and District's 
board resolutions adopting the 2018 PM<INF>2.5</INF> Plan.\20\
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    \18\ Chapter 5 (``Demonstration of Federal Requirements for the 
1997 PM<INF>2.5</INF> Standard'') and Chapter 6 (``Demonstration of 
Federal Requirements for the 2006 PM<INF>2.5</INF> Standard'') of 
the 2018 PM<INF>2.5</INF> Plan pertain to the 1997 PM<INF>2.5</INF> 
NAAQS and 2006 PM<INF>2.5</INF> NAAQS, respectively. The EPA has 
acted on Chapter 6 in our rulemaking for the 2006 PM<INF>2.5</INF> 
NAAQS. See 80 FR 44192 (July 22, 2020). The EPA has proposed to act 
on Chapter 5 as part of a separate rulemaking on the 1997 annual 
PM<INF>2.5</INF> NAAQS. See 86 FR 38652 (July 22, 2021).
    \19\ The CARB 2018 Staff Report includes CARB's review of, among 
other things, the 2018 PM<INF>2.5</INF> 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 2018 Staff 
Report [on the 2018 PM<INF>2.5</INF> Plan].
    \20\ CARB Resolution 19-1, ``2018 PM<INF>2.5</INF> 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 PM<INF>2.5</INF> 
Standards,'' November 15, 2018.
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    The appendices to the 2018 PM<INF>2.5</INF> Plan, in order of their 
evaluation in this proposal, include the following: (i) Appendix 
(``App.'') B (``Emissions Inventory''); (ii) 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 2018 Staff Report; (iii) control 
strategy appendices, including App. C (``Stationary Source Control 
Measure Analyses'') and App. D (``Mobile Source Control Measures 
Analyses''); and (iv) App. H (``RFP, Quantitative Milestones, and 
Contingency''). The 2018 PM<INF>2.5</INF> Plan addresses requirements 
for MVEBs in the ``Transportation Conformity'' section of App. D.\21\
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    \21\ See D-119 to D-131.
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    The 2018 PM<INF>2.5</INF> 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 appendices on ``Public Education and Technology Advancement'' 
(App. F), ``Ambient PM<INF>2.5</INF> Data Analysis'' (App. A), ``New 
Source Review and Emission Reduction Credits'' (App. I) and ``Summary 
of Significant Comments and Responses'' (App. M), as well other 
chapters and appendices that are primarily relevant to the Serious area 
plan requirements, including App. E (``Incentive-Based Strategy''), 
App. J (``Modeling Emission Inventory''), App. K (``Modeling Attainment 
Demonstration''), and App. L (``Modeling Protocol'').
    Lastly, on February 11, 2020, CARB submitted, via the EPA State 
Planning Electronic Collaboration System, a revised version of App. H 
(``RFP, Quantitative Milestones, and Contingency'') that replaces the 
version submitted with the 2018 PM<INF>2.5</INF> Plan on May 10, 2019. 
All references to App. H of the 2018 PM<INF>2.5</INF> Plan in this 
proposed rule are to the revised version of Appendix H submitted 
February 11, 2020.

C. Procedural Requirements for SIPs and SIP Revisions

    Sections 110(a)(1) and (2) and 110(l) of the CAA require each state 
to provide reasonable public notice and an opportunity for a public 
hearing prior to the adoption and submittal 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 an opportunity for a 
public hearing was provided consistent with the EPA's implementing 
regulations in 40 CFR 51.102.
    Both the District and CARB satisfied applicable statutory and 
regulatory requirements for reasonable public notice and hearing prior 
to adoption and submission of the 2016 PM<INF>2.5</INF> Plan and the 
2018 PM<INF>2.5</INF> Plan. The District provided public notice and 
opportunity for public comment prior to its September 15, 2016 public 
hearing on and adoption of the 2016 PM<INF>2.5</INF> Plan.\22\ CARB 
also provided public notice and opportunity for public comment prior to 
its October 20, 2016 public hearing,\23\ where the 2016 
PM<INF>2.5</INF> Plan was tabled.
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    \22\ SJVUAPCD, ``Notice of Public Hearing, Adopt the Proposed 
2016 Moderate Area Plan for the 2012 PM<INF>2.5</INF> Standard,'' 
August 16, 2016, and SJVUAPCD Governing Board Resolution 16-9-10.
    \23\ CARB, ``Notice of Public Meeting to Consider the 2016 
PM<INF>2.5</INF> State Implementation Plan for the San Joaquin 
Valley,'' September 20, 2016.
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    Subsequently, the District provided public notice and opportunity 
for public comment prior to its November 15, 2018 public hearing on and 
adoption of the 2018 PM<INF>2.5</INF> Plan.\24\ CARB also provided 
public notice and opportunity for public comment prior to its January 
24, 2019 public hearing,\25\ when CARB adopted the 2016 
PM<INF>2.5</INF> Plan and the 2018 PM<INF>2.5</INF> Plan.\26\ 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.<SUP>27 28</SUP> 
Therefore, we find that the 2016 PM<INF>2.5</INF> Plan and the 2018 
PM<INF>2.5</INF> Plan meet the procedural requirements for public 
notice and hearing in CAA sections 110(a) and 110(l) and 40 CFR 51.102.
---------------------------------------------------------------------------

    \24\ SJVUAPCD, ``Notice of Public Hearing for Adoption of 
Proposed 2018 PM<INF>2.5</INF> Plan for the 1997, 2006, and 2012 
Standards,'' October 16, 2018, and SJVUAPCD Governing Board 
Resolution 18-11-16.
    \25\ CARB, ``Notice of Public Meeting to Consider the 2018 
PM<INF>2.5</INF> State Implementation Plan for the San Joaquin 
Valley,'' December 21, 2018.
    \26\ CARB Resolution 19-1. See also J&K Court Reporting, LLC, 
``Meeting, State of California Air Resources Board,'' October 20, 
2016 (transcript of CARB's public hearing), 186-190.
    \27\ For the 2016 PM<INF>2.5</INF> Plan: CARB, ``Board Meeting 
Comments Log,'' available at https://www.arb.ca.gov/lispub/comm/bccommlog.php?listname=sjvpmplan2016 (accessed August 20, 2021); J&K 
Court Reporting, LLC, ``Meeting, State of California Air Resources 
Board,'' October 16, 2016 (transcript of CARB's public hearing), 
available at https://ww3.arb.ca.gov/board/mt/2016/mt102016.pdf 
(accessed December 29, 2020); and 2016 PM<INF>2.5</INF> Plan, App. E 
(``Summary of Significant Comments and Responses''), noting that no 
comments were received during the District's 2016 public review.
    \28\ For the 2018 PM<INF>2.5</INF> Plan: 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 PM<INF>2.5</INF> 
Plan, App. M (``Summary of Significant Comments and Responses'').
---------------------------------------------------------------------------

    We present our evaluation of the 2016 PM<INF>2.5</INF> Plan (and 
2018 PM<INF>2.5</INF> Plan as applicable to the Moderate area 
attainment plan requirements for the 2012 PM<INF>2.5</INF> NAAQS) in 
Section IV of this proposed rule. We present our evaluation of the 2018 
PM<INF>2.5</INF> Plan as applicable to the contingency measure 
requirements for the 2006 PM<INF>2.5</INF> NAAQS in section VII of this 
proposed rule.

III. Clean Air Act Requirements for Moderate PM<INF>2.5</INF> 
Nonattainment Area Plans

    With respect to the statutory requirements for particulate matter 
(PM) attainment plans, the general nonattainment area planning 
requirements of title I, part D of the CAA are found in subpart 1, and 
the attainment planning requirements specifically for PM are found in 
subpart 4.
    The EPA has a longstanding general guidance document that 
interprets the 1990 amendments to the CAA, commonly referred to as the 
General Preamble for the Implementation of Title I of the Clean Air Act 
Amendments of 1990 (``General Preamble'').\29\ The General Preamble 
addresses the relationship between the subpart 1 and subpart 4 
requirements and provides recommendations to states for meeting certain 
statutory requirements for PM attainment plans. As explained in the 
General Preamble, specific requirements applicable to Moderate area 
attainment plan SIP submissions for the PM NAAQS are set forth in 
subpart 4 of part

[[Page 49104]]

D, title I of the Act, but such SIP submissions must also meet the 
general attainment planning provisions in subpart 1 of part D, title I 
of the Act, to the extent these provisions ``are not otherwise subsumed 
by, or integrally related to,'' the more specific subpart 4 
requirements.\30\ The EPA provided further guidance to States on PM 
plan submissions in the Addendum to the General Preamble (``General 
Preamble Addendum'').\31\
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    \29\ General Preamble, 57 FR 13498 (April 16, 1992).
    \30\ Id. at 13538.
    \31\ 59 FR 41998 (August 16, 1994).
---------------------------------------------------------------------------

    To implement the PM<INF>2.5</INF> NAAQS, the EPA has also 
promulgated the ``Fine Particle Matter National Ambient Air Quality 
Standard: State Implementation Plan Requirements; Final Rule'' 
(``PM<INF>2.5</INF> SIP Requirements Rule'').\32\ The PM<INF>2.5</INF> 
SIP Requirements Rule establishes regulatory requirements and provides 
additional guidance applicable to attainment plan submissions for the 
PM<INF>2.5</INF> NAAQS, including the 2012 annual PM<INF>2.5</INF> 
NAAQS and the 2006 24-hour PM<INF>2.5</INF> NAAQS, addressed in this 
section and section VII, respectively, of this proposed rule.
---------------------------------------------------------------------------

    \32\ 81 FR 58010 (August 24, 2016).
---------------------------------------------------------------------------

    The general subpart 1 statutory requirements for attainment plans 
include the following: (i) The section 172(c)(1) requirement for 
reasonably available control measures (RACM)/reasonably available 
control technology (RACT) and attainment demonstrations; (ii) the 
section 172(c)(2) requirement to RFP; (iii) the section 172(c)(3) 
requirement for emissions inventories; (iv) the section 172(c)(5) 
requirement for a nonattainment new source review (NNSR) permitting 
program; and (v) the section 172(c)(9) requirement for contingency 
measures.
    The more specific subpart 4 statutory requirements for Moderate 
PM<INF>2.5</INF> nonattainment areas include the following: (i) The 
section 189(a)(1)(A) and 189(e) NNSR permit program requirements; (ii) 
the section 189(a)(1)(B) requirement for attainment demonstrations; 
(iii) the section 189(a)(1)(C) requirement for RACM; and (iv) the 
section 189(c) requirements for RFP and quantitative milestones. Under 
subpart 4, states with Moderate PM<INF>2.5</INF> nonattainment areas 
must provide for attainment in the area as expeditiously as practicable 
but no later than the latest permissible attainment date under CAA 
section 188(c), i.e., December 31, 2021, for the 2012 PM<INF>2.5</INF> 
NAAQS in the SJV, unless the EPA determines, per section 188(b)(1), 
that the area cannot practicably attain the NAAQS by the Moderate area 
attainment date.\33\ In addition, under subpart 4, direct 
PM<INF>2.5</INF> and all precursors to the formation of 
PM<INF>2.5</INF> are subject to control unless the EPA approves a 
demonstration from the state establishing that a given precursor does 
not contribute significantly to PM<INF>2.5</INF> levels that exceed the 
PM<INF>2.5</INF> NAAQS in the area.\34\
---------------------------------------------------------------------------

    \33\ Generally, under CAA section 188(c), the latest permissible 
attainment date for a Moderate nonattainment area is the end of the 
sixth calendar year after the area's designation as nonattainment. 
Because the EPA designated and classified the San Joaquin Valley as 
a Moderate nonattainment area for the 2012 PM<INF>2.5</INF> NAAQS 
effective April 15, 2015 (80 FR 2206, 2217-2218), the latest 
permissible attainment date for these NAAQS in the San Joaquin 
Valley is December 31, 2021.
    \34\ 40 CFR 51.1006 and 51.1009.
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IV. Review of San Joaquin Valley Plans for Moderate Area Requirements

A. Emissions Inventory

1. Requirements for Emissions Inventories
    Section 172(c)(3) of the CAA 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. We refer to this inventory as the ``base year inventory.'' The 
EPA has established regulatory requirements for base year and other 
emissions inventories in the PM<INF>2.5</INF> SIP Requirements Rule 
\35\ and issued guidance concerning emissions inventories for 
PM<INF>2.5</INF> nonattainment areas.\36\
---------------------------------------------------------------------------

    \35\ 40 CFR 51.1008.
    \36\ 81 FR 58010, 58078-58079 and ``Emissions Inventory Guidance 
for Implementation of Ozone and Particulate Matter National Ambient 
Air Quality Standards (NAAQS) and Regional Haze Regulations,'' EPA, 
May 2017 (``Emissions Inventory Guidance''), available at https://www.epa.gov/air-emissions-inventories/air-emissions-inventory-guidance-implementation-ozone-and-particulate.
---------------------------------------------------------------------------

    The base year emissions inventory 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 PM<INF>2.5</INF> 
NAAQS, the base year emissions inventory must include direct 
PM<INF>2.5</INF> emissions, separately reported filterable and 
condensable PM<INF>2.5</INF> emissions,\37\ and emissions of all 
chemical precursors to the formation of secondary PM<INF>2.5</INF>: 
NO<INF>X</INF>, SO<INF>2</INF>, VOC, and ammonia.\38\ In addition, the 
emissions inventory base year for a Moderate PM<INF>2.5</INF> 
nonattainment area must be one of the three years (i.e., 2011-2013) for 
which monitored data were used to designate the area as nonattainment, 
or another technically appropriate year justified by the state in its 
Moderate area attainment plan submission.\39\
---------------------------------------------------------------------------

    \37\ The Emissions Inventory Guidance identifies the types of 
sources for which the EPA expects states to provide condensable PM 
emissions inventories. Emissions Inventory Guidance, section 4.2.1 
(``Condensable PM Emissions''), 63-65.
    \38\ 40 CFR 51.1008.
    \39\ 40 CFR 51.1008(a)(1)(i).
---------------------------------------------------------------------------

    In its SIP submission, a state must include documentation 
explaining how it calculated emissions data. In estimating mobile 
source emissions, a state should use the latest emissions models and 
planning assumptions available at the time it develops the SIP 
submission. 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.<SUP>40 41</SUP> At the time the 2016 PM<INF>2.5</INF> Plan and 
2018 PM<INF>2.5</INF> Plan were developed, California was required to 
use EMFAC2014 to estimate tailpipe and brake and tire wear emissions of 
PM<INF>2.5</INF>, NO<INF>X</INF>, SO<INF>2</INF>, and VOC from on-road 
mobile sources.\42\
---------------------------------------------------------------------------

    \40\ The EPA released an update to AP-42 in January 2011 that 
revised the equation for estimating paved road dust emissions based 
on an updated data regression that included new emissions tests 
results. (76 FR 6328, February 4, 2011). CARB used the revised 2011 
AP-42 methodology in developing on-road mobile source emissions.
    \41\ AP-42 has been published since 1972 as the primary source 
of the EPA's emission factor information. It contains emission 
factors and process information for more than 200 air pollution 
source categories. A source category is a specific industry sector 
or group of similar emitting sources. The emission factors have been 
developed and compiled from source test data, material balance 
studies, and engineering estimates.
    \42\ The EMFAC model (short for EMission FACtor) is a computer 
model developed by CARB. The EPA approved and announced the 
availability of EMFAC2014 for use in SIP development and 
transportation conformity in California on December 14, 2015 (80 FR 
77337). The EPA's approval of the EMFAC2014 emissions model for SIP 
and conformity purposes was effective on the date of publication in 
the Federal Register. On August 15, 2019, the EPA approved and 
announced the availability of EMFAC2017, the latest update to the 
EMFAC model for use by state and local governments to meet CAA 
requirements (84 FR 41717). EMFAC2017 was not available to the State 
and District at the time they were developing the 2016 
PM<INF>2.5</INF> Plan and had only recently been submitted to the 
EPA on July 20, 2018, prior to the adoption of the 2018 
PM<INF>2.5</INF> Plan.
---------------------------------------------------------------------------

    In addition to the base year inventory submitted to meet the 
requirements of CAA section 172(c)(3), a state must also submit future 
``baseline inventories'' for the projected attainment year, each RFP 
milestone year, and any other year of significance for meeting 
applicable CAA requirements.\43\ By baseline inventories we mean 
projected emissions inventories for future years that account for, 
among other things, the ongoing

[[Page 49105]]

effects of economic growth and adopted emission control requirements. 
The SIP submission should include documentation to explain how the 
state calculated the emissions projections.
---------------------------------------------------------------------------

    \43\ 40 CFR 51.1008(a)(2) and 51.1012(a)(2); see also Emissions 
Inventory Guidance.
---------------------------------------------------------------------------

2. Summary of State's Emissions Inventories
    Within the 2016 PM<INF>2.5</INF> Plan, the annual average planning 
inventories for direct PM<INF>2.5</INF> and all PM<INF>2.5</INF> 
precursors (NO<INF>X</INF>, ammonia, SO<INF>X</INF>,\44\ and VOC) for 
the SJV PM<INF>2.5</INF> nonattainment area, together with 
documentation for the inventories, are found in Appendix B (``Emissions 
Inventory''). In addition, Appendix A (``Air Quality Modeling'') 
contains inventory documentation specific to the air quality modeling 
inventories. These portions of the 2016 PM<INF>2.5</INF> Plan contain 
annual average daily emission inventories for 2013 thru 2022 projected 
from the 2012 actual emissions inventory,\45\ including the 2013 base 
year, the 2019 RFP baseline year, the 2021 Moderate area attainment 
year, and the 2022 post-attainment RFP year. The winter average daily 
inventory is used to evaluate sources of emissions for attainment of 
the 2012 PM<INF>2.5</INF> NAAQS in the 2016 PM<INF>2.5</INF> Plan.\46\
---------------------------------------------------------------------------

    \44\ The 2016 PM<INF>2.5</INF> Plan generally uses ``sulfur 
oxides'' or ``SO<INF>X</INF>'' in reference to SO<INF>2</INF> as a 
precursor to the formation of PM<INF>2.5</INF>. We use 
SO<INF>X</INF> and SO<INF>2</INF> interchangeably throughout this 
notice.
    \45\ 2016 PM<INF>2.5</INF> Plan, App. B, B-18.
    \46\ The 2016 PM<INF>2.5</INF> Plan includes annual average and 
winter day average inventories for PM<INF>2.5</INF> planning 
purposes. The winter average daily planning inventory corresponds to 
the months of November through April, when daily, ambient 
PM<INF>2.5</INF> concentrations are typically highest. 2016 
PM<INF>2.5</INF> Plan, App. B, B-19. The base year inventory is from 
the California Emissions Inventory Development and Reporting System 
(CEIDARS) and future year inventories were estimated using the 
California Emission Projection Analysis Model (CEPAM) version 1.04.
---------------------------------------------------------------------------

    Similarly, within the 2018 PM<INF>2.5</INF> Plan, the annual 
average planning inventories for direct PM<INF>2.5</INF> and all 
PM<INF>2.5</INF> precursors, together with documentation for the 
inventories, are found in Appendix B (``Emissions Inventory''). In 
addition, Appendix J (``Modeling Emission Inventory'') contains 
inventory documentation specific to the air quality modeling 
inventories. These portions of the 2018 PM<INF>2.5</INF> Plan contain 
annual average daily emission inventories for 2013 thru 2028 projected 
from the 2012 actual emissions inventory, \47\ including the 2013 base 
year, the 2019 and 2022 RFP baseline years, the 2025 Serious area 
attainment year, and the 2028 post-attainment RFP year. Both the annual 
average and the winter average daily inventories are used to evaluate 
sources of emissions for attainment of the 2012 PM<INF>2.5</INF> NAAQS 
in the 2018 PM<INF>2.5</INF> Plan.\48\
---------------------------------------------------------------------------

    \47\ 2018 PM<INF>2.5</INF> Plan, App. B, B-18.
    \48\ 2018 PM<INF>2.5</INF> Plan, App. B, B-19. The base year 
inventory is from CEIDARS and future year inventories were estimated 
using CEPAM, version 1.05.
---------------------------------------------------------------------------

    The base year inventories for stationary sources were developed 
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 2016 PM<INF>2.5</INF> Plan and 2018 
PM<INF>2.5</INF> Plan.\49\ Importantly, CARB and the District updated 
the emissions inventory in the 2018 PM<INF>2.5</INF> Plan using the 
latest available activity data and emission methodologies available at 
the time of plan development. The 2013 base year, annual average 
emissions inventories for most source categories did not change or only 
changed plus or minus 0.1 tons per day (tpd) between the two plans.\50\ 
However, the base year emissions inventory from several important 
source categories were smaller in the 2018 PM<INF>2.5</INF> Plan 
relative to the 2016 PM<INF>2.5</INF> Plan based on the latest 
information. These include a 1.2 tpd decrease in direct 
PM<INF>2.5</INF> emissions from residential fuel combustion based on a 
2016 emissions inventory methodology update,\51\ a 0.4 tpd decrease in 
direct PM<INF>2.5</INF> emissions from farming operations based on 
updated estimates by the California Department of Conservation of 
harvested acreage in 2010-2020 rather than 2000-2009,\52\ and a 0.9 tpd 
decrease in NO<INF>X</INF> emissions from trains based on updated 
locomotive data from 2016 on Class I and Class II railroads.\53\ 
Overall, for the 2013 base year, total emissions of both direct 
PM<INF>2.5</INF> and NO<INF>X</INF> were 0.9 tpd smaller in the 2018 
PM<INF>2.5</INF> Plan relative to the 2016 PM<INF>2.5</INF> Plan.
---------------------------------------------------------------------------

    \49\ 2016 PM<INF>2.5</INF> Plan, App. B, section B.3 
(``Emissions Inventory Summary and Methodology''), and 2018 
PM<INF>2.5</INF> Plan, App. B, section B.2 (``Emissions Inventory 
Summary and Methodology'').
    \50\ For example, paved road dust direct PM<INF>2.5</INF> 
emissions decreased 0.1 tpd while off-road equipment NO<INF>X</INF> 
emissions increased by 0.1 tpd between the 2016 and 2018 
PM<INF>2.5</INF> Plans.
    \51\ 2018 PM<INF>2.5</INF> Plan, App. B, B-26.
    \52\ 2018 PM<INF>2.5</INF> Plan, App. B, B-27.
    \53\ 2018 PM<INF>2.5</INF> Plan, App. B, B-34.
---------------------------------------------------------------------------

    Furthermore, the 2016 PM<INF>2.5</INF> Plan's emissions inventory 
does not separately report filterable and condensable PM<INF>2.5</INF> 
emissions. However, the 2018 PM<INF>2.5</INF> Plan includes background, 
methodology, and inventories of condensable and filterable 
PM<INF>2.5</INF> emissions from stationary point and non-point 
combustion sources that are expected to generate condensable 
PM<INF>2.5</INF>.\54\ It provides filterable and condensable emissions 
estimates, expressed as annual PM<INF>2.5</INF> emissions (tons per 
year), for all of the identified source categories for the years 
applicable to the Moderate area timeframe, including the 2013 base 
year, the 2019 RFP year, the 2021 Moderate area attainment year, and 
the 2022 post-attainment RFP year, as well as subsequent years.
---------------------------------------------------------------------------

    \54\ 2018 PM<INF>2.5</INF> Plan, App. B, B-42 to B-44. The EPA 
has approved the emissions inventory submission for the 2006 
PM<INF>2.5</INF> NAAQS in the SJV, including the filterable and 
condensable PM<INF>2.5</INF> inventories. 85 FR 44192 (July 22, 
2020) (final rule); and 85 FR 17382, 17389 (March 27, 2020) 
(proposed rule).
---------------------------------------------------------------------------

    CARB used EMFAC2014 to estimate on-road motor vehicle emissions 
based on transportation activity data from the 2014 Regional 
Transportation Plan adopted by the transportation planning agencies in 
the SJV.\55\ Re-entrained paved road dust emissions were calculated 
using a CARB methodology consistent with the EPA's AP-42 road dust 
methodology.\56\ CARB also provided emissions inventories for off-road 
equipment, including aircraft, trains, recreational boats, construction 
equipment, and farming equipment, among others. CARB uses a suite of 
category-specific models to estimate off-road emissions for many 
categories and, where a new model was not available, used the 
OFFROAD2007 model.\57\
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    \55\ 2016 PM<INF>2.5</INF> Plan, App. B, B-33; and 2018 
PM<INF>2.5</INF> Plan, App. B, B-37. We note that the vehicle miles 
traveled data used in the 2018 PM<INF>2.5</INF> Plan's emissions 
inventory is from the final 2017 Federal Transportation Improvement 
Program from each of the SJV's eight metropolitan planning 
organizations.
    \56\ 2016 PM<INF>2.5</INF> Plan, App. B, B-26; and 2018 
PM<INF>2.5</INF> Plan, App. B, B-28.
    \57\ 2016 PM<INF>2.5</INF> Plan, App. B, B-33 through B-35; and 
2018 PM<INF>2.5</INF> Plan, App. B, B-38 through B-40.
---------------------------------------------------------------------------

    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.\58\ 
In the 2016 PM<INF>2.5</INF> Plan and 2018 PM<INF>2.5</INF> 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 
2022 RFP year and the projected 2025 attainment year, respectively.\59\ 
The plans identify growth factors, control factors, and estimated 
offset use between 2013 and 2022, and between 2013 and 2025, for direct 
PM<INF>2.5</INF>, NO<INF>X</INF>, SO<INF>X</INF>, and VOC emissions by 
source category and lists all pre-base year ERCs

[[Page 49106]]

issued by the District for PM<INF>10</INF>,\60\ NO<INF>X</INF>, 
SO<INF>X</INF>, and VOC emissions, by facility.\61\
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    \58\ 2016 PM<INF>2.5</INF> Plan, App. B, B-19; and 2018 
PM<INF>2.5</INF> Plan, App. B, B-19.
    \59\ 2016 PM<INF>2.5</INF> Plan, App. D, D-1 through D-5; and 
2018 PM<INF>2.5</INF> Plan, App. I, I-1 through I-5.
    \60\ Particulate matter with a diameter of 10 microns or less.
    \61\ 2016 PM<INF>2.5</INF> Plan, App. D, tables D-1 through D-5; 
and 2018 PM<INF>2.5</INF> Plan, App. I, tables I-1 through I-5.
---------------------------------------------------------------------------

    Table 1 provides a summary of the 2018 PM<INF>2.5</INF> Plan's 
winter (24-hour) average inventories in tpd of direct PM<INF>2.5</INF> 
and PM<INF>2.5</INF> precursor emissions for the 2013 base year. Table 
2 provides a summary of 2018 PM<INF>2.5</INF> Plan's annual average 
inventories of direct PM<INF>2.5</INF> and PM<INF>2.5</INF> 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, 
impracticability demonstration, RFP demonstration, and MVEBs in the 
2018 PM<INF>2.5</INF> Plan with respect the Moderate area requirements.

  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.
\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.

3. EPA Evaluation and Proposed Action
    Consistent with the requirement that inventories be based on the 
most current and accurate information available to the State and 
District at the time they were developing the plans and inventories, 
our evaluation for the SJV for the 2012 PM<INF>2.5</INF> NAAQS relies 
primarily on the emissions inventories in the 2018 PM<INF>2.5</INF> 
Plan. The inventories in the 2018 PM<INF>2.5</INF> Plan include the 
latest version of California's mobile source emissions model, 
EMFAC2014, that had been approved by the EPA at the time, and the EPA's 
most recent AP-42 methodology for paved road dust. The inventories 
comprehensively address all source categories in the SJV 
PM<INF>2.5</INF> nonattainment area and are consistent with the EPA's 
inventory guidance.
    In accordance with 40 CFR 51.1008(a), the 2013 base year is one of 
the three years for which monitored data were used for designating the 
area, and it represents annual average emissions of all sources within 
the nonattainment area. Direct PM<INF>2.5</INF> and PM<INF>2.5</INF> 
precursors are included in the inventories, and filterable and 
condensable direct PM<INF>2.5</INF> emissions are identified 
separately.
    With respect to future year baseline projections, we have reviewed 
the growth and control factors and find them acceptable and thus 
conclude that the future baseline emissions projections in the 2016 
PM<INF>2.5</INF> Plan and 2018 PM<INF>2.5</INF> Plan reflect 
appropriate calculation methods and the latest planning assumptions at 
the time the State and District were developing the plans and 
inventories. 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.
    Given the State's impracticability demonstration for attaining the 
2012 PM<INF>2.5</INF> NAAQS in the SJV by the outermost Moderate area 
attainment date, the 2016 PM<INF>2.5</INF> Plan describes the District 
rules achieving post-2013 emission reductions that contribute towards 
attaining the NAAQS.\62\ In our rulemaking on the State's attainment 
plan for the 2006 PM<INF>2.5</INF> NAAQS in the SJV, we reviewed the 
baseline measures identified as 2018 PM<INF>2.5</INF> Plan baseline 
controls to ensure that the measures that are relied upon in the plan 
have been submitted and approved as part of the California SIP.\63\ 
That set of 2018 PM<INF>2.5</INF> Plan baseline measures includes all

[[Page 49107]]

those baseline measures identified in the 2016 PM<INF>2.5</INF> Plan's 
RFP demonstration as achieving emission reductions post-2013. Based on 
that review, we confirm that the stationary and area source baseline 
measures in the 2016 PM<INF>2.5</INF> Plan and 2018 PM<INF>2.5</INF> 
Plan are approved into the SIP and support the emissions reductions for 
future years in the SJV. 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.\64\ We therefore find 
that the future year baseline projections in the 2016 PM<INF>2.5</INF> 
Plan and 2018 PM<INF>2.5</INF> Plan are properly supported by SIP-
approved stationary, area, and mobile source measures.\65\
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    \62\ 2016 PM<INF>2.5</INF> Plan, Table 3-2. This includes 
District rules for open burning; boilers, steam generators, and 
process heaters; flares; glass melting furnaces; stationary internal 
combustion engines; and residential wood burning.
    \63\ EPA, ``Technical Support Document, General Evaluation, San 
Joaquin Valley PM<INF>2.5</INF> Plan for the 2006 PM<INF>2.5</INF> 
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 PM<INF>2.5</INF> Plan, along with 
information on the EPA's approval of these rules.
    \64\ See, e.g., 81 FR 39424 (June 16, 2016), 82 FR 14447 (March 
21, 2017), and 83 FR 23232 (May 18, 2018).
    \65\ The baseline emissions projections in the 2016 
PM<INF>2.5</INF> Plan assume implementation of CARB's zero emissions 
vehicle (ZEV) sales mandate and greenhouse gas (GHG) standards, 
based on the approved EMFAC2014 model and assumptions that were 
available at the time of the SIP's development. On September 27, 
2019, the U.S. Department of Transportation and the EPA (the 
Agencies) issued a notice of final rulemaking for 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). In response to 
SAFE I, CARB developed EMFAC off-model adjustment factors to account 
for anticipated changes in on-road emissions. On March 12, 2020, the 
EPA informed CARB that the EPA considers these adjustment factors to 
be acceptable for future use. See letter dated March 12, 2020, from 
Elizabeth J. Adams, EPA Region IX, to Steven Cliff, CARB. 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 
that it is impracticable for the SJV 2012 PM<INF>2.5</INF> Moderate 
area to attain by the Moderate area attainment date of December 31, 
2021.
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    For these reasons, we are proposing to approve the 2013 base year 
emissions inventory in the 2018 PM<INF>2.5</INF> 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 2016 
PM<INF>2.5</INF> Plan and 2018 PM<INF>2.5</INF> Plan satisfy the 
requirements of 40 CFR 51.1008(a)(2) and 51.1012(a)(2) and provide an 
adequate basis for the control measure, RFP, and impracticability 
demonstrations in the 2016 PM<INF>2.5</INF> Plan and 2018 
PM<INF>2.5</INF> Plan, respectively.

B. PM2.5 Precursors

1. Requirements for Control of PM<INF>2.5</INF> Precursors
    The provisions of subpart 4 of part D, title I of the CAA do not 
define the term ``precursor'' for purposes of PM<INF>2.5</INF>, 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 
NO<INF>X</INF>, SO<INF>2</INF>, VOC, and ammonia as precursors to the 
formation of PM<INF>2.5</INF>. Accordingly, the attainment plan 
requirements of subpart 4 apply to emissions of all four precursor 
pollutants and direct PM<INF>2.5</INF> from all types of stationary, 
area, and mobile sources, except as otherwise provided in the Act 
(e.g., in CAA section 189(e)).
    Section 189(e) of the Act requires that the control requirements 
for major stationary sources of direct PM<INF>10</INF> (which includes 
PM<INF>2.5</INF>) also apply to major stationary sources of 
PM<INF>10</INF> precursors, except where the Administrator determines 
that such sources do not contribute significantly to PM<INF>10</INF> 
levels that exceed the standard in the area. Section 189(e) contains 
the only express exception to the control requirements under subpart 4 
(e.g., requirements for RACM, RACT, BACM, best available control 
technology (BACT), MSM, and NNSR) for sources of direct 
PM<INF>2.5</INF> and PM<INF>2.5</INF> precursor emissions. 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 PM<INF>2.5</INF> 
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 PM<INF>10</INF> precursors in the nonattainment area 
under CAA section 172(c)(1) and subpart 4,\66\ 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 
PM<INF>10</INF> levels in the nonattainment area.\67\
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    \66\ General Preamble, 13539-13542.
    \67\ Courts have upheld this approach to the requirements of 
subpart 4 for PM<INF>10</INF>. See, e.g., Assoc. of Irritated 
Residents v. EPA, et al., 423 F.3d 989 (9th Cir. 2005).
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    Under the PM<INF>2.5</INF> 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 PM<INF>2.5</INF> levels that exceed 
the standard in the area.\68\ If the EPA determines that the 
contribution of the precursor to PM<INF>2.5</INF> 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.\69\
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    \68\ 40 CFR 51.1006(a)(1).
    \69\ Id.
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    We are evaluating the 2016 PM<INF>2.5</INF> Plan and 2018 
PM<INF>2.5</INF> Plan with respect to the Moderate area requirements in 
accordance with the presumption embodied within subpart 4 that all 
PM<INF>2.5</INF> precursors must be addressed in the State's evaluation 
of potential control measures, unless the State adequately demonstrates 
that emissions of a particular precursor or precursors do not 
contribute significantly to ambient PM<INF>2.5</INF> levels that exceed 
the PM<INF>2.5</INF> NAAQS in the nonattainment area. In reviewing any 
determination by the State to exclude a PM<INF>2.5</INF> precursor from 
the required evaluation of potential control measures, we consider both 
the magnitude of the precursor's contribution to ambient 
PM<INF>2.5</INF> concentrations in the nonattainment area and the 
sensitivity of ambient PM<INF>2.5</INF> concentrations in the area to 
reductions in emissions of that precursor.
2. Summary of State's Precursor Demonstrations
    The State presents analyses of PM<INF>2.5</INF> precursors in both 
the 2016 PM<INF>2.5</INF> Plan and the 2018 PM<INF>2.5</INF> Plan and 
primarily relies on sensitivity-based contribution analyses to 
determine whether each PM<INF>2.5</INF> plan precursor contributes 
significantly to ambient PM<INF>2.5</INF> levels that exceed the 2012 
PM<INF>2.5</INF> NAAQS. We summarize below key points from the State's 
analyses and conclusions for each pollutant, focusing on the three 
precursors (ammonia, SO<INF>X</INF>, and VOC) that the State concludes 
do not contribute significantly to PM<INF>2.5</INF> levels that exceed 
the 2012 PM<INF>2.5</INF> NAAQS in the SJV.
    In the 2016 PM<INF>2.5</INF> Plan, the State's precursor 
demonstration and conclusions are found in section 2.3 (``Summary of 
Modeling Results''), section 3.3 (``Precursor

[[Page 49108]]

Demonstration''), and Appendix A (``Air Quality Modeling''). The State 
estimates that baseline anthropogenic emissions of NO<INF>X</INF>, 
ammonia, SO<INF>X</INF>, and VOC will decrease by 38 percent (%), 1%, 
2%, and 8%, respectively, between 2013 and 2021.\70\ The State does not 
present a concentration-based analysis of the contribution of each 
precursor to ambient PM<INF>2.5</INF> concentrations, but does estimate 
PM<INF>2.5</INF> component concentrations in the 2013 base year across 
all SJV monitoring sites.\71\ The concentrations indicate that each 
precursor may have a significant impact on PM<INF>2.5</INF> levels.\72\ 
The State presents a sensitivity-based precursor analysis using the 
modeled response of ambient PM<INF>2.5</INF> concentrations to a 15% 
increase or decrease in the future baseline emissions of each precursor 
in 2025 (the latest permissible attainment year if the area is 
reclassified to Serious for the 2012 PM<INF>2.5</INF> NAAQS).\73\ For 
each precursor, the State then takes the difference between the 
PM<INF>2.5</INF> concentrations from the 15% increase and the 15% 
decrease to estimate the ambient PM<INF>2.5</INF> response to a 30% 
change in the precursor, and reviews the resulting change at each 
monitor to see whether any response exceeds a threshold of 0.2 
[micro]g/m\3\.\74\
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    \70\ 2016 PM<INF>2.5</INF> Plan, 2-4 and Table 2-1.
    \71\ Id. at Table 2-4.
    \72\ Using the species assignments recommended in the Draft 
Precursor Demonstration Guidance (on page 21) the relevant 
concentrations are as follows: For NO<INF>X</INF>, the nitrate and 
associated ammonium is up to 7.1 [micro]g/m\3\; for SO<INF>2</INF>, 
sulfate is up to 1.7 [micro]g/m\3\; for ammonia, the sum of ammonium 
and nitrate is up to 7.1 [micro]g/m\3\; for VOC the only available 
concentration is for ``OM'' (organic matter), which is up to 8.7 
[micro]g/m\3\, and is likely much higher than the secondary organic 
aerosol that is relevant for VOC as a PM<INF>2.5</INF> precursor. 
All these values are well above the 0.2 [micro]g/m\3\ threshold.
    \73\ 2016 PM<INF>2.5</INF> Plan, App. A, section 5.4 
(``Precursor Sensitivity Analysis'').
    \74\ For the annual PM<INF>2.5</INF> NAAQS, the EPA generally 
expects that a precursor demonstration showing that the air quality 
impact of a given precursor at all relevant locations does not 
exceed a contribution threshold of 0.2 [mu]g/m\3\ will be adequate 
to exempt sources of that precursor from control requirements. 
PM<INF>2.5</INF> Precursor Guidance, 17.
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    The responses range from 0.5 [micro]g/m\3\ to 1.5 [micro]g/m\3\ for 
NO<INF>X</INF>; from 0.1 [micro]g/m\3\ to 0.2 [micro]g/m\3\ for 
ammonia; from 0.1 [micro]g/m\3\ to 0.2 [micro]g/m\3\ for 
SO<INF>X</INF>; and from -0.1 [micro]g/m\3\ to 0.1 [micro]g/m\3\ for 
VOC.\75\ The State concludes that emissions of NO<INF>X</INF> (as well 
as direct PM<INF>2.5</INF>) contribute significantly to ambient 
PM<INF>2.5</INF> levels that exceed the PM<INF>2.5</INF> NAAQS but 
ammonia, SO<INF>X</INF>, and VOC do not contribute significantly to 
such exceedances.\76\ The 2016 PM<INF>2.5</INF> Plan, Appendix A, 
section 5.5 (``Discussion of Precursor Sensitivity'') includes 
additional discussion of ammonia's and VOC's role in the formation of 
ammonium nitrate and VOC's role in the formation of secondary organic 
aerosols.
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    \75\ 2016 PM<INF>2.5</INF> Plan, App. A, tables 24, 26, 28, and 
27, respectively.
    \76\ Id. at 2-6 and 3-3, and App. A, A-52. We note that direct 
PM<INF>2.5</INF> emissions are considered a primary source of 
ambient PM<INF>2.5</INF> (i.e., no further formation in the 
atmosphere is required), and therefore is not considered a precursor 
pollutant under subpart 4, which may differ from a more generalized 
understanding of what contributes to ambient PM<INF>2.5</INF>.
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    In the 2018 PM<INF>2.5</INF> Plan, the State's precursor 
demonstration and conclusions are found in Chapter 7 (``Demonstration 
of Federal Requirements for 2012 PM<INF>2.5</INF> Standard'') and 
Appendix G (``Precursor Demonstration''). CARB also provides clarifying 
information on its precursor assessment, including an Attachment A to 
its letter transmitting the 2018 PM<INF>2.5</INF> Plan to the EPA \77\ 
and further clarifications in four 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 
SO<INF>X</INF> 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''); 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 NO<INF>X</INF>, 
ammonia, SO<INF>X</INF>, and VOC will decrease by 64%, 1%, 6%, and 9%, 
respectively, between 2013 and 2025.\79\ The 2018 PM<INF>2.5</INF> Plan 
provides both concentration-based and sensitivity-based analyses of 
precursor contributions to ambient PM<INF>2.5</INF> concentrations in 
the SJV. Based on these analyses, the State concludes that emissions of 
NO<INF>X</INF> (as well as direct PM<INF>2.5</INF>) contribute 
significantly to ambient PM<INF>2.5</INF> levels that exceed the 
PM<INF>2.5</INF> NAAQS in the SJV but ammonia, SO<INF>X</INF>, and VOC 
do not contribute significantly to such exceedances.
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    \79\ 2018 PM<INF>2.5</INF> Plan, Ch. 7, 7-5 and Table 7-2. 
Notably, the estimated 64% reduction in NO<INF>X</INF> from 2013 to 
2025 (per the 2018 PM<INF>2.5</INF> Plan) is much larger than the 
estimated 38% reduction in NO<INF>X</INF> from 2013 to 2021 (per the 
2016 PM<INF>2.5</INF> Plan), reflecting both additional years of 
reductions and additional reductions anticipated from the 2018 
PM<INF>2.5</INF> Plan control strategy. We also note that a copy of 
the contents of the 2018 PM<INF>2.5</INF> Plan, App. G appears in 
the CARB 2018 Staff Report, App. C4 (``Precursor Demonstrations for 
Ammonia, SO<INF>X</INF>, and ROG'').
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    While these analyses are primarily designed to evaluate the role of 
precursors in attaining the 2006 24-hour PM<INF>2.5</INF> NAAQS by 2024 
and the 2012 annual PM<INF>2.5</INF> NAAQS by 2025, they are important 
to the consideration of precursors for the State's Moderate area plan 
because they are based on updated data (e.g., updated emissions 
inventories, as discussed in section IV.A of this proposed rule), use 
an updated methodology to evaluate the sensitivity of ambient 
PM<INF>2.5</INF> to a range of precursor emission reductions, 
consistent with the EPA's guidance, and best reflect the State's 
understanding of the control strategies being implemented in the SJV.
    We summarize the State's analyses and conclusions in the following 
paragraphs. For ammonia, SO<INF>X</INF>, and VOC, CARB assesses the 
2015 annual average concentration of each precursor in ambient 
PM<INF>2.5</INF> at Bakersfield, for which the necessary speciated 
PM<INF>2.5</INF> data is available and where the highest 
PM<INF>2.5</INF> design values have been recorded in most years, and 
compares those concentrations to the recommended annual average 
contribution threshold of 0.2 [micro]g/m\3\ from the EPA's ``Draft 
PM<INF>2.5</INF> Precursor Guidance'' \80\ available at the time the 
State developed the SIP.\81\ The 2015 annual average contributions of 
ammonia, SO<INF>X</INF>, and VOC are 5.2 [micro]g/m\3\, 1.6 [micro]g/
m\3\ and 6.2 [micro]g/m\3\, respectively.
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    \80\ ``PM<INF>2.5</INF> 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.
    \81\ 2018 PM<INF>2.5</INF> Plan, App. G, 3. The 2018 
PM<INF>2.5</INF> Plan presents a graphical representation of annual 
average ambient PM<INF>2.5</INF> components (i.e., crustal 
particulate matter, elemental carbon, organic matter, ammonium 
sulfate, and ammonium nitrate) for 2011-2013 for Bakersfield, 
Fresno, and Modesto. 2018 PM<INF>2.5</INF> Plan, Ch. 3, 3-3 to 3-4.
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    Given that these levels are well above the EPA's recommended 
contribution threshold in the Draft PM<INF>2.5</INF> Precursor 
Guidance, the State models the sensitivity of ambient PM<INF>2.5</INF> 
in the SJV to reductions in each precursor pollutant. For direct 
PM<INF>2.5</INF> and NO<INF>X</INF>, the State models the sensitivity 
of ambient PM<INF>2.5</INF> in the SJV to a 30% reduction in 
anthropogenic emissions of each pollutant in 2013, 2020, and 2024.\82\ 
The State concludes that direct PM<INF>2.5</INF> and NO<INF>X</INF> 
emissions reductions will continue to have a significant impact on 
annual

[[Page 49109]]

and 24-hour PM<INF>2.5</INF> design values in the SJV, with 
NO<INF>X</INF> reductions being particularly important.\83\
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    \82\ 2018 PM<INF>2.5</INF> Plan, Ch. 7, 7-7. The sensitivity-
based analysis used the same modeling platform as that used for the 
2018 PM<INF>2.5</INF> Plan's attainment and RFP demonstrations. CARB 
modeled the impacts of both NO<INF>X</INF> reductions and direct 
PM<INF>2.5</INF> reductions, but the direct PM<INF>2.5</INF> results 
were used only as a point of comparison, as direct PM<INF>2.5</INF> 
emissions must be regulated in all PM<INF>2.5</INF> nonattainment 
areas.
    \83\ Id. Ch. 7, 7-7; and 2018 PM<INF>2.5</INF> Plan, App. G, 2. 
CARB presents its sensitivity analysis for emission reductions in 
direct PM<INF>2.5</INF> and NO<INF>X</INF> in the plan's attainment 
demonstration appendix. 2018 PM<INF>2.5</INF> Plan, App. K, Table 46 
(annual average design values) and Table 50 (24-hour average design 
values).
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    For ammonia, SO<INF>X</INF>, and VOC, the State then models the 
sensitivity of ambient PM<INF>2.5</INF> to 30% and 70% reductions in 
anthropogenic emissions of each precursor pollutant in 2013 (the 2018 
PM<INF>2.5</INF> Plan's base year), 2020 (the modeled attainment year 
for the 1997 PM<INF>2.5</INF> NAAQS), and 2024 (the modeled attainment 
year for the 2006 PM<INF>2.5</INF> NAAQS, and proxy for the modeled 
attainment year of 2025 for the 2012 PM<INF>2.5</INF> NAAQS).\84\ 
Depending on the analysis year and percentage precursor emission 
reduction, the sensitivity of ambient PM<INF>2.5</INF> to reductions in 
annual average precursor emissions ranges from 0.08 [micro]g/m\3\ to 
2.30 [micro]g/m\3\ for ammonia; from -0.05 [micro]g/m\3\ to 0.15 
[micro]g/m\3\ for SO<INF>X</INF>; and from -0.50 [micro]g/m\3\ to 0.40 
[micro]g/m\3\ for VOC.\85\
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    \84\ 2018 PM<INF>2.5</INF> Plan, Ch. 7, 7-7. The 2018 
PM<INF>2.5</INF> Plan precursor demonstration assumes that 2025 
attainment year sensitivities are very similar to those modeled in 
2024. 2018 PM<INF>2.5</INF> Plan, App. G, 10. We note that the State 
only modeled 30% and 70% reductions in SO<INF>X</INF> for 2013, 
finding that the sensitivity of ambient PM<INF>2.5</INF> to such 
changes were below the EPA's recommended threshold.
    \85\ Id. at App. G, tables 2 through 7 for ammonia, tables 8 and 
9 for SO<INF>X</INF>, and tables 10 through 15 for VOC.
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    For ammonia, the modeled sensitivity of ambient PM<INF>2.5</INF> 
levels to a 30% or 70% emission reduction exceed 0.2 [micro]g/m\3\ in 
certain years at specific monitoring sites. We provide a detailed 
summary of these modeling results and our evaluations thereof in the 
``Technical Support Document, EPA Evaluation of Ammonia Precursor 
Demonstration, San Joaquin Valley Moderate Area PM<INF>2.5</INF> Plan 
for the 2012 PM<INF>2.5</INF> NAAQS,'' August 2021 (``EPA's Ammonia 
Precursor TSD''). In contrast, for SO<INF>X</INF> and VOC, the modeled 
sensitivity of ambient PM<INF>2.5</INF> levels to a 30% or 70% emission 
reduction in either precursor is below 0.2 [micro]g/m\3\, including a 
disbenefit at certain monitoring sites (i.e., ambient PM<INF>2.5</INF> 
level increase), in all scenarios except one. For 2013, the State's 
modeling shows an ambient PM<INF>2.5</INF> change greater than 0.2 
[micro]g/m\3\ in response to a 70% VOC emission reduction. According to 
the State, however, such sensitivity results do not reflect the 
atmospheric chemistry in the SJV given the projected emission 
reductions from 2013 to 2024 for all four PM<INF>2.5</INF> precursors, 
especially for VOC and NO<INF>X</INF>.\86\
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    \86\ For a more detailed summary of the State's precursor 
demonstration in the 2018 PM<INF>2.5</INF> Plan for the 2006 24-hour 
PM<INF>2.5</INF> NAAQS, see the EPA's ``Technical Support Document, 
EPA Evaluation of PM<INF>2.5</INF> Precursor Demonstration, San 
Joaquin Valley PM<INF>2.5</INF> Plan for the 2006 PM<INF>2.5</INF> 
NAAQS,'' February 2020 (``EPA's 24-hour PM<INF>2.5</INF> Precursor 
TSD'').
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    The State supplements the sensitivity analysis, particularly for 
ammonia, with consideration of additional information, including 
factors identified in the Draft PM<INF>2.5</INF> Precursor Guidance, 
such as emission trends, the appropriateness of future year versus base 
year sensitivity, available emission controls, and the severity of 
nonattainment.\87\ The PM<INF>2.5</INF> Precursor Guidance confirms 
that these factors may be relevant to a sensitivity-based contribution 
analysis.\88\
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    \87\ 2018 PM<INF>2.5</INF> Plan, App. G, 5.
    \88\ PM<INF>2.5</INF> Precursor Guidance, 18-19 (consideration 
of additional information), 31 (available emission controls), and 
35-36 (appropriateness of future year versus base year sensitivity).
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    For ammonia, the State notes that a 53% reduction in (baseline) 
NO<INF>X</INF> emissions is projected to occur between 2013 and 
2024,\89\ so the conditions in the early years will not persist and the 
future year (2024) is more representative of the Valley's ambient 
conditions than earlier years. The 2018 PM<INF>2.5</INF> 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 PM<INF>2.5</INF> 
Plan's precursor demonstration presents extensive support for the 
State's conclusion regarding an ambient excess of ammonia relative to 
NO<INF>X</INF>, i.e., that particulate ammonium nitrate formation is 
NO<INF>X</INF>-limited, beyond that presented in the 2016 
PM<INF>2.5</INF> Plan's precursor demonstration.
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    \89\ 2018 Plan, App. G, 8.
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3. EPA Evaluation and Proposed Action
    The EPA has evaluated the State's precursor demonstrations in the 
2016 PM<INF>2.5</INF> Plan, as supplemented and updated by the 
precursor demonstrations in the 2018 PM<INF>2.5</INF> Plan, as well as 
other relevant information available to the EPA, consistent with the 
PM<INF>2.5</INF> SIP Requirements Rule and the recommendations in the 
PM<INF>2.5</INF> Precursor Guidance. Based on this evaluation, the EPA 
agrees with the State's conclusion that NO<INF>X</INF> emissions 
contribute significantly to ambient PM<INF>2.5</INF> levels that exceed 
the 2012 PM<INF>2.5</INF> NAAQS in the SJV and that NO<INF>X</INF> 
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, 
SO<INF>X</INF>, and VOC based on a conclusion that emissions of these 
precursor pollutants do not contribute significantly to ambient 
PM<INF>2.5</INF> levels that exceed the 2012 PM<INF>2.5</INF> NAAQS in 
the SJV.
    The State based its analyses on the latest available data and 
studies concerning ambient PM<INF>2.5</INF> 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 PM<INF>2.5</INF> (i.e., in 2015). Given the 
absolute concentrations in 2015 were above the EPA's recommended 
contribution thresholds for both the 24-hour and annual average 
PM<INF>2.5</INF> NAAQS, the State proceeded to a sensitivity-based 
analysis, consistent with the PM<INF>2.5</INF> SIP Requirements Rule.
    For the sensitivity-based analysis, the State performed its 
analyses in a straightforward application of the EPA's recommended 
approach--i.e., for each modeled year and level of emissions reduction 
(in percentages), the State estimated the ambient PM<INF>2.5</INF> 
response using the procedure recommended in the PM<INF>2.5</INF> 
Precursor Guidance, and compared the result to the EPA's recommended 
contribution threshold.\90\ The EPA finds that the performance of the 
photochemical models were adequate for use in estimating the ambient 
PM<INF>2.5</INF> responses.\91\ In particular, for the 2018 
PM<INF>2.5</INF> Plan precursor demonstration, the State considered the 
EPA's recommended range of emission reductions (30% to 70%) for the 
2013 base year, 2020 (an interim year), and 2024 (as a proxy for the 
projected 2025 attainment year for the 2012 PM<INF>2.5</INF> NAAQS), 
and quantified

[[Page 49110]]

the estimated response of ambient PM<INF>2.5</INF> concentrations to 
precursor emission changes in the SJV.
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    \90\ For the 2016 PM<INF>2.5</INF> Plan precursor demonstration, 
CARB modeled a 15% increase and 15% decrease in a precursor and took 
the difference between the resulting PM<INF>2.5</INF> concentrations 
to estimate the ambient PM<INF>2.5</INF> response to a 30% change in 
the precursor, rather than a straight 30% reduction, which would be 
expected to slightly understate the response, as described in the 
EPA's Ammonia Precursor TSD. Nevertheless, this is a reasonable 
approach and the State consulted with the EPA on whether this 
approach using then-available modeling runs would be acceptable.
    \91\ For the 2018 PM<INF>2.5</INF> Plan, the model performance 
is discussed further in section J (``Air Quality Model 
Performance'') of the EPA's ``Technical Support Document, EPA 
Evaluation of Air Quality Modeling, San Joaquin Valley 
PM<INF>2.5</INF> Plan for the 2006 PM<INF>2.5</INF> NAAQS,'' 
February 2020 (``EPA's Modeling TSD''). See further discussion in 
section IV.C of this proposed rule.
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    The State's emissions projections in the 2016 PM<INF>2.5</INF> Plan 
and the 2018 PM<INF>2.5</INF> Plan show that baseline emissions of each 
of these precursors will decrease from the 2013 base year to 2021 and 
2025, respectively (i.e., none of these pollutants is projected to 
increase). These decreases are included in the State's modeled 
projections of ambient PM<INF>2.5</INF> 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 PM<INF>2.5</INF> Precursor Guidance.\92\
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    \92\ PM<INF>2.5</INF> Precursor Guidance, 35.
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    In the subsections that follow, we summarize below our evaluation 
of the State's precursor demonstrations for ammonia, SO<INF>X</INF>, 
and VOC for purposes of the 2012 PM<INF>2.5</INF> NAAQS in the SJV.
a. Ammonia Precursor Demonstration
    In the 2016 PM<INF>2.5</INF> Plan, CARB estimates the ambient 
PM<INF>2.5</INF> response to a 30% reduction in emissions in 2025 and, 
in the 2018 PM<INF>2.5</INF> Plan, CARB estimates the ambient 
PM<INF>2.5</INF> response to both a 30% and a 70% emission reduction in 
2013, 2020, and 2024. We have evaluated CARB's sensitivity-based 
contribution analyses for 2013, 2020, and 2024 (in the 2018 
PM<INF>2.5</INF> Plan) and for 2025 (in the 2016 PM<INF>2.5</INF> 
Plan), and CARB's determination that 2024, as a proxy for the projected 
attainment year of 2025, is more representative of conditions in the 
SJV for purposes of a sensitivity-based analysis, as discussed in the 
following paragraphs. We find it appropriate for the State to consider 
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. We provide a detailed evaluation of the State's precursor 
demonstration for ammonia emissions in the EPA's Ammonia Precursor TSD.
    As part of its analysis in the 2016 PM<INF>2.5</INF> Plan, CARB 
estimates that the ambient PM<INF>2.5</INF> response to a 30% reduction 
in ammonia emissions would range from 0.1 [micro]g/m\3\ to 0.2 
[micro]g/m\3\ in 2025 with 3 of 16 monitoring sites having a response 
of 0.2 [micro]g/m\3\. However, the precursor demonstration in the 2018 
PM<INF>2.5</INF> Plan indicates that the ambient response to a 30% 
ammonia emission reduction would exceed the EPA's recommended 
contribution threshold of 0.2 [micro]g/m\3\ at a number of monitoring 
sites, primarily in the 2013 and 2020 analysis years. For example, the 
sensitivity results for a 30% reduction in ammonia emission reductions 
in 2020 (the closest analysis year to 2021), show that the ambient 
PM<INF>2.5</INF> response at 9 of 15 monitoring sites would exceed the 
0.2 [micro]g/m\3\ threshold. We consider two lines of reasoning 
provided by the State to support its conclusion that ammonia emissions 
do not contribute significantly to ambient PM<INF>2.5</INF> levels that 
exceed the 2012 PM<INF>2.5</INF> NAAQS in the SJV.
    First, multiple researchers have suggested that ammonia emissions 
are underestimated in the SJV by a factor of two to five or more.\93\ 
This conclusion is based on comparing ambient and satellite 
measurements to model results that incorporate estimates of ammonia 
emissions and comparing monitoring or modeling results to what would be 
expected based on the size(s) of the ammonia and other precursor (e.g., 
NO<INF>X</INF>) emission inventories. In a supplemental 
transmittal,\94\ CARB described the results of two analyses confirming 
the likely underestimation of ammonia emissions. CARB compared 
Community Multiscale Air Quality (CMAQ) model predictions of ammonia 
with the 2013 DISCOVER-AQ \95\ aircraft measurements and found that 
ammonia was underpredicted, and noted that this would result in the 
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. As a result of the likely 
ammonia emissions underestimation, the modeled response to ammonia 
precursor reductions in the 2018 PM<INF>2.5</INF> Plan's precursor 
demonstration may be unrealistically large.
---------------------------------------------------------------------------

    \93\ See, e.g., Parrish, D., ``Synthesis of Policy Relevant 
Findings from the CalNex 2010 Field Study, Final Report to the 
Research Division of the California Air Resources Board,'' 2014, 63, 
https://www.esrl.noaa.gov/csd/projects/calnex/; and Kelly, J.T. et 
al. 2018, ``Modeling NH<INF>4</INF>NO<INF>3</INF> 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 4731. See also the EPA's Ammonia Precursor 
TSD for further discussion of ammonia research studies.
    \94\ CARB's April 26, 2021, Precursor Clarification.
    \95\ NASA, ``Deriving Information on Surface conditions from 
COlumn and VERtically Resolved Observations Relevant to Air 
Quality,'' available at https://www.nasa.gov/mission_pages/discover-aq/index.html.
---------------------------------------------------------------------------

    If ammonia emissions were increased in the modeling to correct the 
likely underestimation, then modeled ammonia would be more abundant 
relative to nitrate; particulate nitrate formation would be more 
NO<INF>X</INF>-limited, and less responsive to ammonia reductions; and 
the modeled response to ammonia reductions would be lower than is 
reported in the 2018 PM<INF>2.5</INF> Plan's precursor demonstration 
and likely below the EPA's recommended contribution threshold at most 
monitors in 2021.
    In addition, an upward revision in the ammonia emission estimate 
would make the model response more consistent with the ambient 
measurement studies discussed in the submittal.\96\ The relevant 
studies suggest a very low ambient sensitivity to ammonia, based on 
measured excess ammonia relative to NO<INF>X</INF>, the abundance of 
particulate nitrate relative to gaseous NO<INF>X</INF>, and the large 
abundance of ammonia relative to nitric acid.\97\ The studies all 
conclude that there is a large amount of ammonia left over after 
reacting with NO<INF>X</INF>, so that ammonia emission reductions would 
be expected mainly to reduce the amount of ammonia excess, rather than 
to reduce the particulate amonium nitrate.
---------------------------------------------------------------------------

    \96\ 2018 PM<INF>2.5</INF> 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.
    \97\ Lurmann et al. 2006, ``Processes Influencing Secondary 
Aerosol Formation in the San Joaquin Valley during Winter,'' Journal 
of the Air & Waste Management Association (1995) 56(12):1679-93, 
https://doi.org/10.1080/10473289.2006.10464573; Markovic et al., 
2014, ``Measurements and modeling of the inorganic chemical 
composition of fine particulate matter and associated precursor 
gases in California's San Joaquin Valley during CalNex 2010,'' 
Journal of Geophysical Research--Atmospheres, 119, 6853-6866, 
https://doi.org/10.1002/2013JD021408. CalNex, or California Research 
at the Nexus of Air Quality and Climate Change, was a NOAA-sponsored 
field study during summer 2010. https://www.esrl.noaa.gov/csd/projects/calnex/.
---------------------------------------------------------------------------

    Based on these evaluations, we find that a correction to the likely 
underestimation of the ammonia emission inventory would likely result 
in a modeled response to ammonia reductions below the 0.2 [micro]g/m\3\ 
contribution threshold in 2021.
    Second, the air quality benefit of ammonia emission reductions is 
projected to decline steeply over time and both the Moderate and 
Serious area plans for the 2012 PM<INF>2.5</INF> NAAQS for the SJV have 
been submitted to the EPA. While a concentration-based analysis is the 
initial step for a precursor demonstration under the PM<INF>2.5</INF> 
SIP Requirements Rule,\98\ a precursor

[[Page 49111]]

demonstration may then proceed to a sensitivity-based contribution 
analysis \99\ to consider how sensitive ambient PM<INF>2.5</INF> levels 
would be to emissions reductions. Precursor concentration alone does 
not account for complications of meteorology and chemistry; ambient 
PM<INF>2.5</INF> may be relatively insensitive to emissions reductions 
and, in some circumstances, emissions reductions may even result in 
increased ambient PM<INF>2.5</INF>, i.e., show a ``disbenefit.'' \100\
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    \98\ 40 CFR 51.1006 (a)(1)(i).
    \99\ 40 CFR 51.1006 (a)(1)(ii).
    \100\ An example of a disbenefit is ``sulfate replacement,'' 
which can occur at intermediate ammonia levels when there is not 
enough ammonia to fully react with the SO<INF>X</INF> and 
NO<INF>X</INF> present. Reducing SO<INF>X</INF> emissions reduces 
ambient particulate ammonium sulfate. For each ammonium sulfate, two 
ammonium ions are freed; both can combine with a nitrate, forming 
two particulate ammonium nitrate molecules. The net result of the 
SO<INF>X</INF> emissions decrease is then an increase in ambient 
PM<INF>2.5</INF> concentration. See also the EPA's 24-hour 
PM<INF>2.5</INF> Precursor TSD, 17-18; and West, J.J., Ansari, A.S., 
Pandis, S.N., 1999, ``Marginal PM<INF>2.5</INF>: Nonlinear aerosol 
mass response to sulfate reductions in the eastern United States,'' 
Journal of the Air & Waste Management Association, 49, 1415-1424. 
https://doi.org/10.1080/10473289.1999.10463973.
---------------------------------------------------------------------------

    In selecting the analysis year for a precursor demonstration, we 
find it 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. Based on these considerations, 
we find it reasonable for the State to focus on the ambient 
PM<INF>2.5</INF> 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 PM<INF>2.5</INF> NAAQS. 
We consider the precursor demonstration in the 2018 PM<INF>2.5</INF> 
Plan as part of this evaluation, because the 2018 PM<INF>2.5</INF> Plan 
contains a Serious area attainment plan for the 2012 PM<INF>2.5</INF> 
NAAQS based on modeled emissions projections for 2024 and 2025 that are 
relevant to our evaluation of the ammonia precursor demonstration in 
the 2016 PM<INF>2.5</INF> Plan. The 2018 PM<INF>2.5</INF> Plan provides 
updated analyses with comprehensive modeling and additional information 
beyond that provided in the 2016 PM<INF>2.5</INF> Plan, and the 2024 
model results in the 2018 PM<INF>2.5</INF> Plan corroborate the 2025 
model results in the 2016 PM<INF>2.5</INF> Plan.
    The State's precursor demonstrations in the 2016 PM<INF>2.5</INF> 
Plan and the 2018 PM<INF>2.5</INF> Plan show 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 PM<INF>2.5</INF> level, and by 37% 
averaged over all monitoring sites. In absolute terms, the ambient 
PM<INF>2.5</INF> response declines from 0.24 [micro]g/m\3\ in 2020 to 
0.12 [micro]g/m\3\ in 2024 at Bakersfield-Planz, and from 0.23 
[micro]g/m\3\ to 0.14 [micro]g/m\3\ as averaged over all monitoring 
sites, with the decline being generally larger for the sites with the 
highest projected PM<INF>2.5</INF> levels. Thus, between 2020 and 2024, 
the number of sites at which modeled sensitivity exceeds the 0.2 
[micro]g/m\3\ threshold declines from 9 of 15 to 1 or 2 of 
15.<SUP>101 102</SUP> As discussed above, ammonia sensitivity declines 
because of the shifting atmospheric chemistry caused by NO<INF>X</INF> 
emissions decreases. NO<INF>X</INF> emissions are projected to decrease 
27% between 2020 and 2024 due to baseline measures (e.g., existing 
motor vehicle controls). The decreased NO<INF>X</INF> emissions will 
make ammonia more abundant relative to NO<INF>X</INF>, and even less of 
a limiting factor on PM<INF>2.5</INF> formation. In other words, the 
model response in the future attainment year 2024 gives a more 
realistic assessment of the potential effect of ammonia controls than 
past or current conditions.
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    \101\ 2018 PM<INF>2.5</INF> Plan, App. G, tables 4 & 5, G-11. 
The result for the Madera site is unclear since its monitored 
concentrations are biased high.
    \102\ For 2025, the 2016 PM<INF>2.5</INF> Plan states there are 
no sites are above the contribution threshold. The sensitivities 
show similar declines from 2020 to 2025 of 58% for the monitoring 
site with the highest projected PM<INF>2.5</INF> level and 46% 
averaged over all monitoring sites. Because only a single decimal 
place is provided for 2025, the percent declines are more 
approximate. Extrapolating the 2018 PM<INF>2.5</INF> Plan results to 
2025, the percent declines are 55% and 40%, respectively, which are 
comparable to those for 2024.
---------------------------------------------------------------------------

    Moreover, given the likely underestimate in ammonia emissions in 
the SJV, 2024 modeling results may be more representative even of 
current conditions than 2020 modeling results. For example, if 2013 
ammonia emissions are underestimated by a factor of three, as suggested 
by the CalNex summary report,\103\ then the 2013 ratio of ammonia to 
NO<INF>X</INF> emissions of 1.04 should be about 3.1, instead. The 
emissions ratio of ammonia to NO<INF>X</INF> in 2024 is 2.2, which is 
closer to 3.1 than the emissions ratio of ammonia to NO<INF>X</INF> in 
2020, which is 1.6.\104\ Using 2024 modeling results partly compensates 
for the likely ammonia emissions underestimation.
---------------------------------------------------------------------------

    \103\ Parrish, D., ``Synthesis of Policy Relevant Findings from 
the CalNex 2010 Field Study, Final Report to the Research Division 
of the California Air Resources Board,'' 2014, 63, https://www.esrl.noaa.gov/csd/projects/calnex/.
    \104\ 2018 PM<INF>2.5</INF> Plan, App. B, tables B-2 
(``NO<INF>X</INF>'') and B-5 (``Ammonia''), annual average tpd, 
Grand Total for San Joaquin Valley, B-7 and B-16. The ammonia to 
NO<INF>X</INF> ratio is 329.2/317.2 = 1.04 in 2013; 325.9/203.3 = 
1.6 in 2020; and 324.6/148.9 = 2.2 in 2024.
---------------------------------------------------------------------------

    Finally, the decision on whether to control ammonia does not affect 
the attainment year for the 2012 annual PM<INF>2.5</INF> NAAQS. From 
the 2020 sensitivity results,\105\ a 30% reduction in ammonia emissions 
would reduce the projected PM<INF>2.5</INF> level in 2021 \106\ by 0.24 
[micro]g/m\3\. The design value would decrease from a 2020 baseline 
value of 14.6 [micro]g/m\3\ down to 14.3 [micro]g/m\3\. The State uses 
a 30% ammonia emission reduction as an upper bound in the modeling but 
shows that even a 70% ammonia emission reduction would reduce the 
design value to only 13.8 [micro]g/m\3\. The result of a 30% or even a 
70% ammonia emission reduction, if those were possible, would still be 
well above the NAAQS level of 12.0 [micro]g/m\3\. Attainment would 
remain impracticable in 2021. A decision to evaluate and possibly adopt 
additional ammonia controls in the 2016 PM<INF>2.5</INF> Plan would not 
remove the need for a Serious area plan identifying a later attainment 
year for the 2012 PM<INF>2.5</INF> NAAQS.
---------------------------------------------------------------------------

    \105\ 2018 PM<INF>2.5</INF> Plan, App. G, tables 4 and 6.
    \106\ Sensitivity for the year 2021 is being represented by 
model results for 2020. Given the declining NO<INF>X</INF> emissions 
and corresponding decline in ammonia sensitivity, the actual 
PM<INF>2.5</INF> response to ammonia reductions for 2021 would be 
lower than stated.
---------------------------------------------------------------------------

    Such reductions would also have little effect in 2025. Based on the 
2024 sensitivity results,\107\ if ammonia emissions were reduced by 
30%, the area's 12.0 [micro]g/m\3\ design value would be reduced by 
0.12 [micro]g/m\3\, which would not be considered significant (it is 
below the EPA's recommended threshold of 0.2 [micro]g/m\3\). A 70% 
reduction might lower the design value by 0.36 [micro]g/m\3\ to 11.7 
[micro]g/m\3\. Conceivably that could result in attainment of the 2012 
PM<INF>2.5</INF> NAAQS in 2024 rather than 2025, but it is not clear 
whether reductions of that magnitude are feasible.
---------------------------------------------------------------------------

    \107\ 2018 PM<INF>2.5</INF> 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 
NO<INF>X</INF> emissions.
---------------------------------------------------------------------------

    In sum, we find that the State quantified the sensitivity of 
ambient PM<INF>2.5</INF> levels to reductions in ammonia emissions 
using appropriate modeling techniques that performed well; there is 
likely an underestimation of ammonia emissions in the SJV and, if 
corrected, the modeled response to ammonia reductions would be lower 
than reported; and the State's choice of 2024 and 2025 as the reference 
points for purposes of evaluating the sensitivity of

[[Page 49112]]

ambient PM<INF>2.5</INF> 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 PM<INF>2.5</INF> levels that exceed 
the 2012 PM<INF>2.5</INF> NAAQS in the SJV.
b. SO<INF>X</INF> Precursor Demonstration0.05
    As described in section IV.B.2 of this proposed rule, in the 2016 
PM<INF>2.5</INF> Plan, CARB estimated the ambient PM<INF>2.5</INF> 
response to a 30% reduction in SO<INF>X</INF> emissions in 2025 to 
range from 0.1 [micro]g/m\3\ to 0.2 [micro]g/m\3\, with half the 
monitoring sites having a response of 0.2 [micro]g/m\3\. In the 2018 
PM<INF>2.5</INF> Plan, CARB estimated the 2013 ambient PM<INF>2.5</INF> 
response to a 30% SO<INF>X</INF> emission reduction to range from -0.01 
[micro]g/m\3\ to 0.07 [micro]g/m\3\ and estimated the ambient 
PM<INF>2.5</INF> response to a 70% SO<INF>X</INF> emission reduction to 
range from -0.05 [micro]g/m\3\ to 0.15 [micro]g/m\3\.\108\ The State 
also provides an emissions trend chart that shows SO<INF>X</INF> 
emissions to be steady at approximately 8 tpd from 2013 through 2024. 
Given that the relative levels of SO<INF>X</INF> and ammonia emissions 
over that timeframe remain similar, the State concludes that the 2013 
sensitivities are also representative of future years.\109\ The State 
also provides the ambient PM<INF>2.5</INF> responses in 2013, 2020, and 
2024 to 30% and 70% reductions in SO<INF>X</INF> emissions, all of 
which are below the 0.2 [micro]g/m\3\ contribution threshold.\110\
---------------------------------------------------------------------------

    \108\ 2018 PM<INF>2.5</INF> Plan, App. G, 15-16, tables 8 and 9.
    \109\ 2018 PM<INF>2.5</INF> Plan, App. G, 15.
    \110\ CARB's September 2019 Precursor Clarification.
---------------------------------------------------------------------------

    We note that the 2016 PM<INF>2.5</INF> Plan's sensitivity estimates 
for 2025 are at or below the EPA's recommended contribution threshold 
of 0.2 [micro]g/m\3\, and that the 2018 PM<INF>2.5</INF> 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 that the latter precursor demonstration 
was based on updated data and an updated methodology, and the steady 
SO<INF>X</INF> 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 SO<INF>X</INF> 
precursor demonstration. The supplemental results provided by the State 
for 2020 and 2024 support this conclusion.
    Therefore, on the basis of these modeled ambient PM<INF>2.5</INF> 
responses to SO<INF>X</INF> emission reductions in the SJV, and the 
facts and circumstances of the area, the EPA proposes to approve the 
State's demonstration that SO<INF>X</INF> emissions do not contribute 
significantly to ambient PM<INF>2.5</INF> levels that exceed the 2012 
PM<INF>2.5</INF> NAAQS in the SJV.
c. VOC Precursor Demonstration
    In the 2016 PM<INF>2.5</INF> Plan, CARB estimated the ambient 
PM<INF>2.5</INF> response to a 30% difference in VOC emissions in 2025 
to range from -0.1 [micro]g/m\3\ to 0.1 [micro]g/m\3\. In the 2018 
PM<INF>2.5</INF> Plan, the State found that the ambient 
PM<INF>2.5</INF> response to VOC emission reductions were generally 
below the EPA's recommended contribution threshold of 0.2 [micro]g/
m\3\, and often predicted an increase in ambient PM<INF>2.5</INF> 
levels in response to such reductions (i.e., a disbenefit), except for 
a 70% emission reduction for the 2013 base year, where the State 
predicted the ambient PM<INF>2.5</INF> response to be above both 
recommended thresholds at a majority of sites.\111\
---------------------------------------------------------------------------

    \111\ 2018 PM<INF>2.5</INF> Plan, App. G, 18-19, tables 10 and 
11.
---------------------------------------------------------------------------

    We note that the 2016 PM<INF>2.5</INF> Plan's sensitivity estimates 
for 2025 are at or below the EPA's recommended contribution threshold 
of 0.2 [micro]g/m\3\, and that the 2018 PM<INF>2.5</INF> 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.\112\ Finally, the State concludes that VOC 
emissions do not contribute significantly to PM<INF>2.5</INF> levels 
that exceed the 2012 PM<INF>2.5</INF> NAAQS.
---------------------------------------------------------------------------

    \112\ 2018 PM<INF>2.5</INF> Plan, App. G, 19-20.
---------------------------------------------------------------------------

    The EPA has evaluated and agrees with the State's determination in 
the 2018 PM<INF>2.5</INF> Plan that the projected 2024 attainment year 
is more representative of conditions in the SJV for sensitivity-based 
analyses and that VOC reductions in 2024 would mostly result in a 
disbenefit to ambient PM<INF>2.5</INF> levels. The EPA agrees that the 
9% VOC emissions decrease from 2013 to 2024 supports reliance on the 
2024 modeling results. Furthermore, there is a large decrease in 
NO<INF>X</INF> emissions over this period, as described in section 
IV.B.2 of this proposed rule, that affects the atmospheric chemistry 
with respect to ambient PM<INF>2.5</INF> formation from VOC emissions. 
The 9% VOC emission reductions and the vast majority of NO<INF>X</INF> 
emissions reductions are expected to result from baseline measures 
already in effect. Therefore, we find it reasonable to rely on future 
year 2024 modeled responses to VOC reductions. The EPA also finds 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 ``Technical Support Document, EPA Evaluation of PM<INF>2.5</INF> 
Precursor Demonstration, San Joaquin Valley PM<INF>2.5</INF> Plan for 
the 2006 PM<INF>2.5</INF> NAAQS,'' February 2020 (``EPA's 2006 NAAQS 
Precursor TSD''), VOC reductions led to less peroxyacetyl nitrate 
formation, and greater availability of nitrate to form particulate 
ammonium nitrate.\113\
---------------------------------------------------------------------------

    \113\ EPA's 2006 NAAQS Precursor TSD, 22.
---------------------------------------------------------------------------

    For these reasons, we propose to approve the State's demonstration 
that VOC emissions do not contribute significantly to ambient 
PM<INF>2.5</INF> levels that exceed the 2012 PM<INF>2.5</INF> NAAQS in 
the SJV.

C. Air Quality Modeling

1. Requirements for Air Quality Modeling
    Section 189(a)(1)(B) of the CAA requires each state in which a 
Moderate area is located to submit a plan that includes a demonstration 
(including air quality modeling) of either (i) attainment of the 
PM<INF>2.5</INF> NAAQS by the applicable attainment date, or (ii) 
attainment by that date is impracticable. The 2016 PM<INF>2.5</INF> 
Plan includes a demonstration that attainment by the Moderate 
attainment date is impracticable.
    The EPA's PM<INF>2.5</INF> modeling guidance \114\ (``Modeling 
Guidance'' and ``Modeling Guidance Update'') recommends that a 
photochemical model, such as the Comprehensive Air Quality Model with 
Extensions or CMAQ, be used to simulate a base case, with 
meteorological and emissions inputs reflecting a base case year, to 
replicate concentrations monitored in that year. The model application 
to the base year undergoes a performance evaluation to ensure that it 
satisfactorily corroborates the concentrations monitored in that year. 
The model may then be used to simulate emissions occurring in other 
years required for a

[[Page 49113]]

plan, namely the base year (which may differ from the base case year) 
and future year.\115\ The modeled response to the emission changes 
between those years is used to calculate relative response factors 
(RRFs) that are applied to the design value in the base year to 
estimate the projected design value in the future year for comparison 
against the NAAQS. Separate RRFs are estimated for each chemical 
species component of PM<INF>2.5</INF>, 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 design value must be speciated 
using available chemical species measurements--that is, each day's 
measured PM<INF>2.5</INF> concentration must be split into its species 
components. The Modeling Guidance provides additional detail on the 
recommended approach.\116\
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    \114\ Memorandum dated November 29, 2018, from Richard Wayland, 
Air Quality Assessment Division, Office of Air Quality Planning and 
Standards (OAQPS), EPA, to Regional Air Division Directors, EPA, 
Subject: ``Modeling Guidance for Demonstrating Air Quality Goals for 
Ozone, PM<INF>2.5</INF>, 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 PM<INF>2.5</INF> 
NAAQS Modeled Attainment Test,'' (``Modeling Guidance Update'').
    \115\ 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.''
    \116\ Modeling Guidance, section 4.4, ``What is the Modeled 
Attainment Tests for the Annual Average PM<INF>2.5</INF> NAAQS.''
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    The EPA has not issued modeling guidance specific to 
impracticability demonstrations but believes that a state seeking to 
make such a demonstration generally should provide air quality modeling 
similar to that required for an attainment demonstration.\117\ The main 
difference is that for an impracticability demonstration, the 
implementation of the SIP control strategy (including RACM) does not 
result in attainment of the standard by the Moderate area attainment 
date.
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    \117\ 81 FR 58010, 58048.
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    For an attainment demonstration, a thorough review of all modeling 
inputs and assumptions (including consistency with EPA guidance) is 
especially important because the modeling must ultimately support a 
conclusion that the plan (including its control strategy) will provide 
for timely attainment of the applicable NAAQS. In contrast, for an 
impracticability demonstration, the end point is a reclassification to 
Serious, which triggers the requirement for a new Serious area 
attainment plan with a new air quality modeling analysis, and a new 
control strategy.\118\ Thus, the Serious area planning process would 
provide an opportunity to refine the modeling analysis and/or correct 
any technical shortcomings in the impracticability demonstration. 
Therefore, the burden of proof will generally be lower for an 
impracticability demonstration compared to an attainment 
demonstration.\119\
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    \118\ CAA section 189(b)(1).
    \119\ 81 FR 58010, 58049.
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2. Summary of State's Air Quality Modeling
    In the 2016 PM<INF>2.5</INF> Plan, the State discussed its air 
quality modeling in section 2.3 (``Summary of Modeling Results'') and 
Appendix A (``Air Quality Modeling'') and concludes that it is not 
practicable to attain the 2012 PM<INF>2.5</INF> NAAQS in the SJV by 
December 31, 2021. The State used CMAQ (version 5.02) to model three 
simulations: A 2013 base year to demonstrate that the model reasonably 
reproduced observed PM<INF>2.5</INF> concentrations, a 2013 reference 
base year simulation that excluded exceptional events such as 
wildfires, and a 2021 future year based on the reference year but using 
projected 2021 emissions. For the base year simulation, CARB conducted 
photochemical modeling with the CMAQ model using inputs developed from 
routinely available meteorological and air quality data, as well as 
more detailed and extensive data from the DISCOVER-AQ field study 
conducted in January to February 2013.
    The State then generated site- and species-specific RRFs for the 
ammonium ion, nitrate ion, sulfate ion, organic carbon, elemental 
carbon, and a combined grouping of other primary PM<INF>2.5</INF> 
material for the 2021 future year simulation and calculated future year 
design values by multiplying the species- and site-specific RRFs by the 
corresponding quarterly mean component concentrations. The State summed 
the quarterly mean components to determine quarterly mean 
PM<INF>2.5</INF> concentrations, which it subsequently averaged to 
determine the annual design values. The future year design values 
reflect the weighted quarterly average concentration from the 
projections of five years of data. The State projected future year 
annual PM<INF>2.5</INF> design values for the 2021 Moderate area 
attainment year for the 2012 PM<INF>2.5</INF> NAAQS.
    The 2021 baseline simulation used emission levels projected from 
the 2013 base year that reflect all control measures adopted by the 
time of the 2016 PM<INF>2.5</INF> Plan's development that would be 
implemented by December 31, 2021. This simulation indicates that the 
2012 annual PM<INF>2.5</INF> standard will not be met in the SJV in 
2021. The projected 2021 control scenario design value is 14.8 
[micro]g/m\3\ at Bakersfield-Planz, which is typically the monitoring 
site that records the highest PM<INF>2.5</INF> levels in the SJV.
    The 2018 PM<INF>2.5</INF> Plan includes a modeled demonstration 
projecting that the SJV will attain the 2012 annual PM<INF>2.5</INF> 
NAAQS by December 31, 2025. It also includes a modeled demonstration 
projecting attainment of the 1997 annual PM<INF>2.5</INF> NAAQS by 
December 31, 2020, with a design value of 14.6 [micro]g/m\3\ at 
Bakersfield-Planz. While the plan does not explicitly have a 
demonstration of impracticability of attaining the 2012 
PM<INF>2.5</INF> NAAQS by 2021, the latter projections of annual 
PM<INF>2.5</INF> concentrations in 2020 provides additional information 
on which to judge the practicability of attaining by 2021 in that it is 
the closest analysis year available and represents modeling based on 
updated data. These projections lend support for the 2016 
PM<INF>2.5</INF> Plan indication that the 2012 annual PM<INF>2.5</INF> 
standard will not be met in the SJV in 2021.
    The Plan's primary discussion of the photochemical modeling appears 
in Appendix K (``Modeling Attainment Demonstration'') of the 2018 
PM<INF>2.5</INF> 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 6.4 (``Attainment 
Demonstration and Modeling'') of the 2018 PM<INF>2.5</INF> Plan. The 
State provides a conceptual model of PM<INF>2.5</INF> 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 PM<INF>2.5</INF> 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

[[Page 49114]]

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 both Appendix A of the 2016 PM<INF>2.5</INF> Plan and 
Appendix K of the 2018 PM<INF>2.5</INF> Plan included statistical and 
graphical measures of model performance.
    The EPA previously evaluated and approved the modeling conducted 
for the 2006 24-hour PM<INF>2.5</INF> NAAQS as part of the 2018 
PM<INF>2.5</INF> Plan; see the EPA's ``Technical Support Document, EPA 
Evaluation of Air Quality Modeling, San Joaquin Valley PM<INF>2.5</INF> 
Plan for the 2006 PM<INF>2.5</INF> NAAQS,'' February 2020 (``EPA's 2006 
NAAQS Modeling TSD'') accompanying that action for details.\120\ The 
conclusions in the EPA's 2006 NAAQS Modeling TSD focused on the 24-hour 
PM<INF>2.5</INF> NAAQS; in this notice we extend the evaluation with 
information specific to the annual PM<INF>2.5</INF> NAAQS. Unless 
otherwise noted, the discussion applies to both the modeling in both 
the 2016 PM<INF>2.5</INF> Plan (Appendix A) and 2018 PM<INF>2.5</INF> 
Plan (Appendix K), since they followed the same model platform 
development procedures, and had identical meteorological inputs, very 
similar emissions inputs, and very similar model performance.
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    \120\ The model performance is discussed further in section J 
(``Air Quality Model Performance'') of the EPA's 2006 NAAQS Modeling 
TSD.
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    Most aspects of the 2018 PM<INF>2.5</INF> 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 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, PM<INF>2.5</INF> 
species, and calendar quarter. But for the 24-hour averaging time, the 
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. The EPA previously found that the procedures used 
in the 2018 PM<INF>2.5</INF> Plan for the 24-hour PM<INF>2.5</INF> 
NAAQS generally followed the EPA's recommendations and were adequate. 
For the current action, the EPA finds that State procedures \121\ for 
estimating future design values for the annual PM<INF>2.5</INF> NAAQS 
generally followed the EPA's recommendations and are adequate.
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    \121\ 2018 PM<INF>2.5</INF> Plan, App. K, 18.
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    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, since calculation of 
the design value for the 24-hour PM<INF>2.5</INF> NAAQS uses the 98th 
percentile concentrations, i.e., the top 2%. For the annual average, 
peak concentrations continue to be important, but lower concentration 
days are also important since 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); and applying the RRF to 
monitored base year concentration anchors the final model prediction to 
unbiased real-world concentrations. Further, RRFs are calculated on a 
quarterly basis, so the bias correction can better account for 
emissions sources and atmospheric chemistry that differ between the 
seasons.
    The 2018 PM<INF>2.5</INF> Plan did not have a separate model 
performance evaluation for the 24-hour and annual PM<INF>2.5</INF> 
averaging times; it used statistical and graphical analyses applicable 
to both. For the most part, the EPA's 2006 NAAQS Modeling TSD did not 
distinguish between the two averaging times either but drew conclusions 
for the 24-hour averaging time rather than the annual averaging time. 
It did note a large negative bias (underprediction) in the ammonium and 
nitrate performance statistics \122\ for the 2nd quarters for 
monitoring sites in Bakersfield, Fresno, and Visalia; and we add here 
that the 3rd quarter has similar negative bias. The negative model bias 
in the 2016 PM<INF>2.5</INF> Plan was slightly better than in the 2018 
PM<INF>2.5</INF> Plan, i.e., the underprediction was slightly less. 
Underprediction of total PM<INF>2.5</INF> 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.\123\ The EPA's 
2006 NAAQS Modeling TSD noted that since those quarters have 
concentrations that are less than half of those in the 1st and 4th, 
this may not be much of a concern for the annual average. (It is of 
less concern for the 24-hour average, since peak 24-hour concentrations 
occur in winter, i.e., in the 1st and 4th quarters.) As noted above, 
the RRF procedure removes much of this bias, so the underprediction in 
the model performance evaluation does not directly translate into an 
underpredicted 2020 design value. In addition, the 2018 
PM<INF>2.5</INF> Plan shows that annual model performance for each 
PM<INF>2.5</INF> species is quite good relative to that seen in other 
modeling studies, for multiple performance statistics.\124\
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    \122\ 2016 PM<INF>2.5</INF> Plan, App. A 48ff, tables 15 through 
18; 2018 PM<INF>2.5</INF> Plan, App. K, 48ff, tables 20 through 23.
    \123\ 2016 PM<INF>2.5</INF> Plan, App. A, 107ff, Supplemental 
materials, Figures S.37-S.52; 2018 PM<INF>2.5</INF> Plan, App. K, 
131ff, Supplemental materials, Figures S.41-S.52.
    \124\ 2016 PM<INF>2.5</INF> Plan, App. A, 46, Figure 13; 2018 
PM<INF>2.5</INF> Plan, App. K, 54, Figure 14.
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    The high 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 the State's choice of model for the 
impracticability demonstration and the extensive discussion in the 2016 
PM<INF>2.5</INF> Plan about modeling procedures, tests, and performance 
analyses, as well as the State's modeling choices, procedures, test, 
and performance analyses in the 2018 PM<INF>2.5</INF> Plan.\125\ We 
find the State's analyses consistent with the EPA's guidance on 
modeling for PM<INF>2.5</INF> attainment planning purposes. Based on 
these reviews, we find that the modeling in the 2016 PM<INF>2.5</INF> 
Plan and 2018 PM<INF>2.5</INF>

[[Page 49115]]

Plan is adequate for the purposes of supporting the RFP demonstration 
and the demonstration of impracticability in the 2016 PM<INF>2.5</INF> 
Plan.
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    \125\ For a more detailed summary of the State's air quality 
modeling in the 2018 PM<INF>2.5</INF> Plan with respect to the 2006 
24-hour PM<INF>2.5</INF> NAAQS, rather than the 2012 annual 
PM<INF>2.5</INF> NAAQS, please refer to the EPA's 2006 NAAQS 
Modeling TSD.
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D. Reasonably Available Control Measures and Control Strategy

1. Requirements for RACM/RACT and Control Strategies
    The general subpart 1 attainment plan requirement for RACM/RACT is 
described in CAA section 172(c)(1), which requires that attainment plan 
submissions ``provide for the implementation of all reasonably 
available control measures as expeditiously as practicable (including 
such reductions in emissions from existing sources in the area as may 
be obtained through the adoption, at a minimum, of reasonably available 
control technology)'' and provide for attainment of the NAAQS.
    The attainment planning requirements specific to PM<INF>2.5</INF> 
under subpart 4 likewise impose an obligation upon states with 
nonattainment areas classified as Moderate to develop attainment plans 
that require RACM/RACT on sources of direct PM<INF>2.5</INF> and all 
PM<INF>2.5</INF> plan precursors. CAA section 189(a)(1)(C) requires 
that Moderate area PM<INF>2.5</INF> SIPs contain provisions to assure 
that RACM/RACT are implemented no later than four years after 
designation of the area. The EPA reads CAA section 172(c)(1) and 
189(a)(1)(C) together to require that attainment plans for Moderate 
nonattainment areas provide for the implementation of RACM/RACT for 
existing sources of PM<INF>2.5</INF> and those PM<INF>2.5</INF> 
precursors subject to control in the nonattainment area as 
expeditiously as practicable but no later than four years after 
designation.\126\
---------------------------------------------------------------------------

    \126\ This interpretation is consistent with guidance provided 
in the General Preamble, 13540.
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    The PM<INF>2.5</INF> SIP Requirements Rule defines RACM as ``any 
technologically and economically feasible measure that can be 
implemented in whole or in part within 4 years after the effective date 
of designation of a PM<INF>2.5</INF> nonattainment area and that 
achieves permanent and enforceable reductions in direct 
PM<INF>2.5</INF> emissions and/or PM<INF>2.5</INF> plan precursor 
emissions from sources in the area. RACM includes reasonably available 
control technology (RACT).'' \127\ The EPA has historically defined 
RACT as the lowest emission limitation that a particular stationary 
source is capable of meeting by the application of control technology 
that is reasonably available considering technological and economic 
feasibility.\128\
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    \127\ 81 FR 58010, 58035.
    \128\ General Preamble, 13541 and 57 FR 18070, 18073-18074.
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    Under the PM<INF>2.5</INF> SIP Requirements Rule, those control 
measures that otherwise meet the definition of RACM but ``can only be 
implemented in whole or in part during the period beginning 4 years 
after the effective date of designation of a nonattainment area and no 
later than the end of the sixth calendar year following the effective 
date of designation of the area'' must be adopted and implemented as 
``additional reasonable measures.'' \129\
---------------------------------------------------------------------------

    \129\ 40 CFR 51.1000, 51.1009(a)(4)(i)(B), and 
51.1009(a)(4)(ii)(B).
---------------------------------------------------------------------------

    States must provide written justification in a SIP submission for 
eliminating potential control options from further review on the basis 
of technological or economic infeasibility.\130\ An evaluation of 
technological feasibility may include consideration of factors such as 
a source's process and operating conditions, raw materials, physical 
plant layout, and non-air quality and energy impacts (e.g., increased 
water pollution, waste disposal, and energy requirements).\131\ An 
evaluation of economic feasibility may include consideration of factors 
such as cost per ton of pollution reduced (cost-effectiveness), capital 
costs, and operating and maintenance costs.\132\ Absent other 
indications, the EPA presumes that it is reasonable for similar sources 
to bear similar costs of emission reductions. Economic feasibility of 
RACM/RACT is thus largely informed by evidence that other sources in a 
source category have in fact applied the control technology, process 
change, or measure in question in similar circumstances.\133\
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    \130\ 40 CFR 51.1009(a)(3).
    \131\ 40 CFR 51.1009(a)(3); see also 57 FR 18070, 18073-18074.
    \132\ Id.
    \133\ 57 FR 18070, 18074.
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    Consistent with these requirements, CARB and SJVUAPCD must 
implement RACM, including RACT, for sources of direct PM<INF>2.5</INF> 
and PM<INF>2.5</INF> plan precursors no later than April 15, 2019, and 
must implement additional reasonable measures for these sources no 
later than December 31, 2021.
2. Summary of State's Control Strategy
    The RACM/RACT evaluation for sources of direct PM<INF>2.5</INF> and 
NO<INF>X</INF> emissions in the SJV area is presented in Chapter 3 of 
the 2016 PM<INF>2.5</INF> Plan and in Attachment 1 and Attachment 2 to 
the 2016 PM<INF>2.5</INF> Plan. Attachment 1 to the 2016 
PM<INF>2.5</INF> Plan contains (1) a copy of the BACM/BACT and MSM 
control strategy evaluation for stationary and area sources that the 
District adopted on April 16, 2015, as part of its ``2015 Plan for the 
1997 PM<INF>2.5</INF> Standard'' (``2015 PM<INF>2.5</INF> Plan''), and 
(2) a copy of the RACM/RACT control strategy evaluation for stationary 
and area sources that the District adopted on June 16, 2016, as part of 
its ``2016 Plan for the 2008 8-Hour Ozone Standard'' (``2016 Ozone 
Plan'').\134\ Attachment 2 to the 2016 PM<INF>2.5</INF> Plan contains 
(1) a copy of the BACM/BACT and MSM control strategy evaluation for 
mobile sources that CARB adopted on May 21, 2015, as part of the 2015 
PM<INF>2.5</INF> Plan, and (2) a copy of the RACM/RACT control strategy 
evaluation for mobile sources that CARB adopted on July 21, 2016, as 
part of the 2016 Ozone Plan.\135\
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    \134\ 2016 PM<INF>2.5</INF> Plan, Attachment 1 (comprising 2015 
PM<INF>2.5</INF> Plan, App. C (``BACM and MSM for Stationary and 
Area Sources'')) and 2016 Ozone Plan, App. C (``Stationary and Area 
Source Control Strategy Evaluations''). See also SJVUAPCD Governing 
Board Resolution 15-4-7A, April 16, 2015 (adopting the 2015 
PM<INF>2.5</INF> Plan) and SJVUAPCD Governing Board Resolution 16-6-
20, June 16, 2016 (adopting the 2016 Ozone Plan).
    \135\ 2016 PM<INF>2.5</INF> Plan, Attachment 2 (comprising 2015 
PM<INF>2.5</INF> Plan, App. D (``BACM and MSM for Mobile Sources 
(Provided by ARB)'') and 2016 Ozone Plan, App. D (``Mobile Source 
Control Strategy''). See also CARB Resolution 15-9, May 21, 2015 
(adopting the 2015 PM<INF>2.5</INF> Plan) and CARB Resolution 16-8, 
July 21, 2016 (adopting the 2016 Ozone Plan).
---------------------------------------------------------------------------

    The 2015 PM<INF>2.5</INF> Plan and 2016 Ozone Plan contain 
comprehensive analyses to identify potential emission reduction 
opportunities for sources of direct PM<INF>2.5</INF> and NO<INF>X</INF> 
emissions and to determine whether additional measures would be 
technologically and economically feasible for implementation in the 
SJV.\136\ The District states in the 2016 PM<INF>2.5</INF> Plan that it 
has not identified any new emission control technologies that could 
further reduce emissions in the SJV area, that the cost of technologies 
recently found not to be cost-effective has not changed, and that 
potential additional measures remain economically infeasible, 
consistent with the analyses and conclusions in the 2015 
PM<INF>2.5</INF> Plan and the 2016 Ozone Plan.\137\ Based on these 
analyses, the District concludes that the 2016 PM<INF>2.5</INF> Plan 
satisfies the RACM/RACT requirement for stationary and area sources of 
direct PM<INF>2.5</INF> and NO<INF>X</INF> emissions. The 2018 
PM<INF>2.5</INF> Plan, submitted May 10, 2019, supplements these 
analyses by providing updated evaluations of potential control measures 
for sources of direct PM<INF>2.5</INF> and NO<INF>X</INF> emissions and 
the District's rationale for finding that additional

[[Page 49116]]

control measures are not technologically and economically feasible for 
implementation in the SJV.\138\
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    \136\ 2016 PM<INF>2.5</INF> Plan, Ch. 3, 3-5 to 3-6.
    \137\ Id.
    \138\ 2018 PM<INF>2.5</INF> Plan, App. C (``Stationary Source 
Control Measure Analyses'').
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    With respect to mobile sources, the 2016 PM<INF>2.5</INF> Plan 
states that CARB has implemented the most stringent mobile source 
emissions control program in the nation, including emission standards 
for new vehicles, in-use programs for exiting vehicles and fleets, 
cleaner fuels, and incentive programs to accelerate penetration of 
cleanest vehicles.\139\ CARB states that its analyses of these mobile 
source control measures are presented in the 2015 PM<INF>2.5</INF> Plan 
and the 2016 Ozone Plan (included as Attachment 2 to the 2016 
PM<INF>2.5</INF> Plan) and states that there are no additional 
reasonably available control measures that would advance attainment of 
the PM<INF>2.5</INF> NAAQS in the SJV.\140\ Based on these analyses, 
CARB concludes that the 2016 PM<INF>2.5</INF> Plan satisfies the RACM/
RACT requirement for mobile sources of direct PM<INF>2.5</INF> and 
NO<INF>X</INF> emissions. The 2018 PM<INF>2.5</INF> Plan, submitted May 
10, 2019, supplements these analyses by providing updated evaluations 
of CARB's mobile source control measures and its rationale for finding 
that additional control measures are not technologically and 
economically feasible for implementation in the SJV at this time.\141\
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    \139\ 2016 PM<INF>2.5</INF> Plan, 3-6.
    \140\ CARB 2016 Staff Report, 13.
    \141\ 2018 PM<INF>2.5</INF> Plan, App. D (``Mobile Source 
Control Measure Analyses'').
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    Finally, with respect to transportation control measures (TCMs), 
the 2016 PM<INF>2.5</INF> Plan states that the eight county 
metropolitan planning organizations (MPOs) of the SJV (``SJV MPOs'') 
identified and evaluated all TCMs during development of the plan.\142\ 
The plan states that the SJV MPOs implement TCMs in CAA section 108(f) 
consistent with the Congestion Mitigation and Air Quality cost 
effectiveness policy when developing each MPO's Regional Transportation 
Plan. In 2016 the Valley MPOs revisited the minimum cost effectiveness 
standard for TCMs during the development of the MPOs' 2017 Federal 
Transportation Improvement Program.\143\ The District concludes that 
the Valley MPOs are implementing all reasonable TCMs under the MPOs' 
jurisdictions and that adoption of additional TCMs would not expedite 
attainment of the 2012 PM<INF>2.5</INF> NAAQS in the SJV.\144\ The 2018 
PM<INF>2.5</INF> Plan, submitted May 10, 2019, supplements these 
analyses by providing an updated discussion of the transportation 
control measures being implemented in the SJV.\145\
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    \142\ 2016 PM<INF>2.5</INF> Plan, 3-6.
    \143\ 2016 PM<INF>2.5</INF> Plan, 3-23 to 3-24. See also 2016 
PM<INF>2.5</INF> Plan, Attachment 2, App. D, section D.2.2 (D-16 
through D-18) and Attachment D (``Adopted Transportation Control 
Measures'').
    \144\ 2016 PM<INF>2.5</INF> Plan, 3-6.
    \145\ 2018 PM<INF>2.5</INF> Plan, App. D, D-127 to D-128 (noting 
that the MPOs revisited the minimum cost effectiveness standard 
during the development of their 2018 Regional Transportation Plans 
and 2019 Federal Transportation Improvement Program and concluded 
that they were implementing all reasonable transportation control 
measures).
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3. EPA's Evaluation and Proposed Action
    We have reviewed the State and District's demonstrations in the 
2016 PM<INF>2.5</INF> Plan concerning RACM/RACT and additional 
reasonable measures for mobile, stationary, and area sources of direct 
PM<INF>2.5</INF> and one PM<INF>2.5</INF> plan precursor (i.e., 
NO<INF>X</INF>) in the SJV. Our evaluation relies primarily on our 
previous evaluations of the State and District rules in connection with 
our February 12, 2019 approval of the SJV RACM demonstration for the 
2008 ozone NAAQS (for NO<INF>X</INF> emission sources) \146\ and in 
connection with our July 22, 2020 approval of the State and District's 
demonstrations to meet the BACM (including BACT) and MSM requirements 
for the 2006 PM<INF>2.5</INF> NAAQS.\147\ We provide a detailed 
discussion of these evaluations in the technical support document for 
this proposed rule.\148\ Based on these reviews, we propose to find 
that the District's rules provide for the implementation of RACM and 
additional reasonable measures \149\ for stationary and area sources of 
direct PM<INF>2.5</INF> and NO<INF>X</INF> and that CARB's current 
program implements RACM and additional reasonable measures for mobile 
sources of direct PM<INF>2.5</INF> and NO<INF>X</INF> emissions for 
purposes of the 2012 PM<INF>2.5</INF> NAAQS in the SJV.
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    \146\ 84 FR 3302.
    \147\ 85 FR 44192 (final rule approving 2018 PM<INF>2.5</INF> 
Plan as meeting, inter alia, BACM/BACT and MSM requirements for 2006 
PM<INF>2.5</INF> NAAQS). Because the RACM/RACT and additional 
reasonable measure control strategy in the 2016 PM<INF>2.5</INF> 
Plan is very similar to the BACM/BACT and MSM control strategy in 
the 2018 PM<INF>2.5</INF> Plan, and because the State's and 
District's control measure evaluations in the 2016 PM<INF>2.5</INF> 
Plan substantially overlap with their BACM/BACT and MSM control 
evaluations in the 2018 PM<INF>2.5</INF> Plan, we rely primarily on 
our evaluation of the State's and District's BACM/BACT and MSM 
control measure evaluations in the 2018 PM<INF>2.5</INF> Plan (see 
proposed rule, 85 FR 17382 (March 27, 2020) and final rule, 85 FR 
44192) to support our evaluation of the RACM/RACT and additional 
reasonable measure control strategy in the 2016 PM<INF>2.5</INF> 
Plan.
    \148\ EPA, Region IX, Air Division, ``Technical Support 
Document, EPA Evaluation of RACM/RACT and Additional Reasonable 
Measures, San Joaquin Valley Moderate Area Plan for the 2012 
PM<INF>2.5</INF> NAAQS,'' August 2021.
    \149\ The 2018 PM<INF>2.5</INF> Plan identifies Rule 4901 
(``Wood Burning Fireplaces and Wood Burning Heaters''), as amended 
June 20, 2019, as an additional reasonable measure that is scheduled 
for implementation beginning in 2020. 2018 PM<INF>2.5</INF> Plan, 
Table 4-4 (``Proposed Regulatory Measures''). The EPA approved Rule 
4901 into the California SIP on July 22, 2020. 85 FR 44206 (final 
rule approving Rule 4901) and 85 FR 44192 (determination that Rule 
4901 implements BACM and MSM for residential wood burning).
---------------------------------------------------------------------------

    With respect to transportation controls, we find that the SJV MPOs 
have well-established TCM development programs in which TCMs are 
continuously identified, reviewed, and evaluated throughout the 
transportation planning process. Overall, we believe that the programs 
developed and administered by CARB and the SJV MPOs provide for the 
implementation of RACM and additional reasonable measures for sources 
of direct PM<INF>2.5</INF> and NO<INF>X</INF> in the SJV.
    For these reasons, we propose to find that the 2016 
PM<INF>2.5</INF> Plan provides for the implementation of RACM and 
additional reasonable measures for all sources of direct 
PM<INF>2.5</INF> and NO<INF>X</INF> as expeditiously as practicable, 
for purposes of implementing the 2012 PM<INF>2.5</INF> NAAQS in the SJV 
in accordance with the requirements of CAA section 189(a)(1)(C) and 40 
CFR 51.1009.

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 
PM<INF>2.5</INF> also apply to major stationary sources of 
PM<INF>2.5</INF> precursors, except where the Administrator determines 
that such sources do not contribute significantly to PM<INF>2.5</INF> 
levels that exceed the standards in the area.\150\ The control 
requirements applicable to major stationary sources of direct 
PM<INF>2.5</INF> in a Moderate PM<INF>2.5</INF> nonattainment area 
include, at a minimum, the requirements of an NNSR permit program 
meeting the requirements of CAA sections 172(c)(5) and 189(a)(1)(A). In 
the PM<INF>2.5</INF> SIP Requirements Rule, we established a deadline 
for states to submit NNSR plan revisions to implement the 
PM<INF>2.5</INF> NAAQS 18 months after an area is initially designated 
and classified as a Moderate nonattainment area.\151\
---------------------------------------------------------------------------

    \150\ General Preamble, 13539 and 13541-13542.
    \151\ 81 FR 58010, 58115.
---------------------------------------------------------------------------

    California submitted NNSR SIP revisions for the SJV to address the 
subpart 4 requirements for Moderate PM<INF>2.5</INF> nonattainment 
areas on May 19,

[[Page 49117]]

2011.\152\ The EPA fully approved these SIP revisions on September 17, 
2014.\153\ California also submitted NNSR SIP revisions for the SJV to 
address the subpart 4 requirements for Moderate and Serious 
PM<INF>2.5</INF> nonattainment areas on November 20, 2019. The EPA is 
evaluating this SIP submission and will act on it in a separate 
rulemaking. Accordingly, in this action, the EPA is not addressing the 
NNSR control requirements that apply to major stationary sources of 
direct PM<INF>2.5</INF> and PM<INF>2.5</INF> precursors in the SJV 
under CAA section 189(e).
---------------------------------------------------------------------------

    \152\ Letter dated May 19, 2011, from Robert D. Fletcher, Deputy 
Executive Officer, CARB, to Jared Blumenfeld, Regional 
Administrator, EPA Region IX.
    \153\ 79 FR 55637.
---------------------------------------------------------------------------

F. Demonstration That Attainment by Moderate Area Attainment Date Is 
Impracticable

1. Requirements for Attainment/Impracticability of Attainment 
Demonstrations
    Section 189(a)(1)(B) of the CAA requires that each Moderate area 
attainment plan include a demonstration that the plan provides for 
attainment by the applicable Moderate area attainment date or, 
alternatively, that attainment by such date is impracticable. This 
provision explicitly requires that a demonstration of attainment be 
based on air quality modeling but does not require such modeling for an 
impracticability demonstration. Although the EPA expects that most 
impracticability demonstrations will also be supported by air quality 
modeling, it may be possible in some cases to support an 
impracticability demonstration with ambient PM<INF>2.5</INF> data and 
other relevant non-modeling information.\154\
---------------------------------------------------------------------------

    \154\ 81 FR 58010, 58048 and 58049.
---------------------------------------------------------------------------

    Section 188(c) of the CAA states, in relevant part, that the 
Moderate area attainment date ``shall be as expeditiously as 
practicable but no later than the end of the sixth calendar year after 
the area's designation as nonattainment . . . .'' For the SJV, which 
was initially designated as nonattainment for the 2012 PM<INF>2.5</INF> 
standard effective April 15, 2015, the applicable Moderate area 
attainment date under section 188(c) for this standard is as 
expeditiously as practicable but no later than December 31, 2021.
    In SIP submissions that demonstrate impracticability, the state 
should document how its required control strategy in the attainment 
plan represents the application of RACM/RACT and additional reasonable 
measures, at minimum, to existing sources. The EPA believes it is 
appropriate to require adoption of all available control measures that 
are reasonable, i.e., technologically and economically feasible, in 
areas that do not demonstrate timely attainment, even where those 
measures cannot be implemented within the 4-year timeframe for 
implementation of RACM/RACT under CAA section 189(a)(1)(C). The 
impracticability demonstration will then be based on a showing that the 
area cannot attain by the applicable attainment date, notwithstanding 
implementation of the required controls.
2. Summary of State's Impracticability Demonstration
    The 2016 PM<INF>2.5</INF> Plan includes a demonstration, based on 
air quality modeling, that even with the implementation of RACM/RACT 
and additional reasonable measures for all appropriate sources, 
attainment by December 31, 2021, is not practicable. The 
impracticability demonstration is included in Appendix A of the 2016 
PM<INF>2.5</INF> Plan. As described in section IV.C.2 of this proposed 
rule, the projected 2021 control scenario design value is 14.8 
[micro]g/m\3\ at Bakersfield-Planz, which is typically the monitoring 
site that records the highest PM<INF>2.5</INF> levels in the SJV.
    As further described in section IV.C.2 of this proposed rule, the 
2018 PM<INF>2.5</INF> Plan includes a modeled demonstration that 
projects annual PM<INF>2.5</INF> concentrations in 2020 that provides 
additional information on which to judge the practicability of 
attaining by 2021 in that it is the closest analysis year available and 
represents modeling based on updated data. These projections lend 
support for the 2016 PM<INF>2.5</INF> Plan conclusion that the 2012 
annual PM<INF>2.5</INF> standard will not be met in the SJV in 2021.
    Table 3 shows the projected annual PM<INF>2.5</INF> concentrations 
at the four PM<INF>2.5</INF> monitoring sites in the SJV that are 
equipped with comprehensive particulate matter species 
characterization, as well as Bakersfield-Planz, given that it is the 
site with the highest annual PM<INF>2.5</INF> concentrations in the 
base year and projected future year. From the 2016 PM<INF>2.5</INF> 
Plan, the projections are for 2021 (latest permissible Moderate area 
attainment year); from the 2018 PM<INF>2.5</INF> Plan, the projections 
are for 2020 (the analysis year closest to 2021).

                          Table 3--Projected Annual PM2.5 Concentrations at Selected Monitoring Sites in the San Joaquin Valley
                                                                      [[micro]g/m3]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                          2016 PM2.5 Plan                                 2018 PM2.5 Plan
                                                         -----------------------------------------------------------------------------------------------
                      Site location                                                         Difference                                      Difference
                                                               2013            2021         (2013-2021)        2013            2020         (2013-2021)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Bakersfield-Planz.......................................            17.3            14.8            -2.5            17.2            14.6            -2.6
Bakersfield-California Ave..............................            16.0            13.6            -2.4            16.0            13.5            -2.5
Visalia North Church....................................            16.2            13.7            -2.5            16.2            13.5            -2.7
Fresno-Garland..........................................            15.0            12.9            -2.1            15.0            12.4            -2.6
Modesto-14th St.........................................            13.0            11.2            -1.8            13.0            11.0            -2.0
--------------------------------------------------------------------------------------------------------------------------------------------------------
Sources: 2016 PM2.5 Plan, Table 2-2, and 2018 PM2.5 Plan, App. K, Table 25.

3. EPA Evaluation and Proposed Action
    The impracticability demonstration in the 2016 PM<INF>2.5</INF> 
Plan is based on air quality modeling that is generally consistent with 
applicable EPA guidance. We find the modeling adequate to support the 
impracticability demonstration in the plan, as discussed in section 
IV.C.3 of this notice. Similarly, the attainment modeling demonstration 
in the 2018 PM<INF>2.5</INF> Plan is generally consistent with 
applicable EPA guidance and provides additional support that it is 
impracticable to attain the 2012 PM<INF>2.5</INF> NAAQS by 2021.
    We have also evaluated the State's control measure demonstration, 
which relies on its BACM/MSM

[[Page 49118]]

demonstration, as updated by the 2018 PM<INF>2.5</INF> Plan, and find 
that it provides for the expeditious implementation of all RACM/RACT 
and additional reasonable measures that may feasibly be implemented at 
this time, consistent with the requirements of CAA sections 172(c)(1) 
and 189(a)(1)(C) for the 2012 PM<INF>2.5</INF> NAAQS in the SJV, as 
discussed in section IV.D of this notice.
    Finally, we have reviewed available monitored data to assess the 
practicability of attaining by 2021. Specifically, the certified 2018-
2020 annual average design value for SJV is 17.6 [micro]g/m\3\ (at 
Bakersfield-Planz), with exceedances of the 12.0 [micro]g/m\3\ standard 
throughout the area.\155\ We note that the SJV may have experienced 
higher than normal PM<INF>2.5</INF> concentrations in 2018 and 2020 due 
to wildfires in the surrounding areas during the summer and fall 
months.\156\ This monitored data similarly supports the State's 
demonstration that it is impracticable to attain the 2012 
PM<INF>2.5</INF> NAAQS by the end of 2021.
---------------------------------------------------------------------------

    \155\ EPA design value workbook dated May 24, 2021, 
``pm25_designvalues_2018_2020_final_05_24_21.xlsx,'' worksheets 
``Table 1a'' and ``Table 5a.'' The certified design value includes 
all available data; no data flagged for exceptional events have been 
excluded. The EPA's Air Quality System (AQS) contains ambient air 
pollution data collected by federal, state, local, and tribal air 
pollution control agencies from thousands of monitors. More 
information is available at: https://www.epa.gov/aqs. See also EPA, 
2010-2020 AQS Design Value Report, AMP480, June 30, 2021.
    \156\ Concentrations at all 17 monitors in the SJV with data 
spanning 2018 to 2020 are significantly higher in 2018 and 2020 
relative to concentrations in 2019, possibly due to the wildfires in 
those years. 86 FR 38652, 38665, Table 5 (July 22, 2021) (proposed 
rule on the 2018 PM<INF>2.5</INF> Plan for the 1997 annual 
PM<INF>2.5</INF> NAAQS of 15.0 [micro]g/m\3\). Notwithstanding the 
potential effect of wildfires, ambient PM<INF>2.5</INF> levels in 
the SJV remain well above the 2012 PM<INF>2.5</INF> NAAQS standard 
of 12.0 [micro]g/m\3\.
---------------------------------------------------------------------------

    Based on this evaluation, we propose to approve the State's 
demonstration in the 2016 PM<INF>2.5</INF> Plan that attainment of the 
2012 PM<INF>2.5</INF> NAAQS in the SJV by the Moderate area attainment 
date of December 31, 2021, is impracticable, consistent with the 
requirements of CAA section 189(a)(1)(B)(ii). On this basis, we also 
propose to reclassify the SJV as a Serious nonattainment area, which 
would trigger requirements for the State to submit a Serious area 
attainment plan consistent with the requirements of subparts 1 and 4 of 
part D, title I of the Act (as described in section V of this notice).

G. Reasonable Further Progress and Quantitative Milestones

1. Requirements for Reasonable Further Progress and Quantitative 
Milestones
    Section 172(c)(2) of the CAA states that all nonattainment area 
plans shall require RFP. In addition, CAA section 189(c) requires that 
all PM<INF>2.5</INF> nonattainment area plans include quantitative 
milestones that the state must achieve every three years until the area 
is redesignated to attainment and that demonstrate RFP. Section 171(1) 
defines RFP as ``such annual incremental reductions in emissions of the 
relevant air pollutant as are required by [Part D] or may reasonably be 
required by the Administrator for the purpose of ensuring attainment of 
the applicable [NAAQS] by the applicable date.'' Neither subpart 1 nor 
subpart 4 of part D, title I of the Act requires a set percentage of 
emission reductions that states must achieve in any given year for 
purposes of satisfying the RFP requirement.
    For purposes of the PM<INF>2.5</INF> NAAQS, the EPA has interpreted 
the RFP requirement to require that nonattainment area plans show 
annual incremental emission reductions sufficient to maintain generally 
linear progress toward attainment by the applicable deadline.\157\ As 
discussed in the EPA's guidance in the General Preamble Addendum,\158\ 
requiring linear progress in reductions of direct PM<INF>2.5</INF> and 
any individual precursor in a PM<INF>2.5</INF> plan may be appropriate 
in the following situations:
---------------------------------------------------------------------------

    \157\ 59 FR 41998, 42015.
    \158\ Id.
---------------------------------------------------------------------------

    <bullet> The pollutant is emitted by a large number and range of 
sources,
    <bullet> the relationship between any individual source or source 
category and overall air quality is not well known,
    <bullet> a chemical transformation is involved (e.g., secondary 
particulate contributes significantly to PM<INF>2.5</INF> levels over 
the standard), and/or
    <bullet> the emission reductions necessary to attain the 
PM<INF>2.5</INF> standard are inventory-wide.\159\
---------------------------------------------------------------------------

    \159\ Id.
---------------------------------------------------------------------------

    The General Preamble Addendum indicates that requiring linear 
progress may be less appropriate in other situations, such as in 
situations where:
    <bullet> there are a limited number of sources of direct 
PM<INF>2.5</INF> or a precursor,
    <bullet> the relationships between individual sources and air 
quality are relatively well defined, and/or
    <bullet> the emission control systems utilized (e.g., at major 
point sources) will result in a swift and dramatic emission reductions.
    In nonattainment areas characterized by any of these latter 
conditions, RFP may be better represented as 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 sources, the EPA's guidance indicates that 
``RFP should be met by `adherence to an ambitious compliance schedule' 
which is likely to periodically yield significant emission reductions 
of direct PM<INF>2.5</INF> or a PM<INF>2.5</INF> precursor.'' \160\
---------------------------------------------------------------------------

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

    Attainment plans for the PM<INF>2.5</INF> NAAQS must include 
detailed schedules for compliance with emission regulations in the 
nonattainment area and provide corresponding emissions projections for 
each applicable milestone year that represent generally linear or 
stepwise progress in reducing emissions on an annual basis.\161\ In 
reviewing an attainment plan under subpart 4, the EPA considers whether 
the annual incremental emission 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<INF>2.5</INF> earlier 
to provide greater public health benefits.\162\
---------------------------------------------------------------------------

    \161\ 40 CFR 51.1012(a) and 59 FR 41998, 42016.
    \162\ Id.
---------------------------------------------------------------------------

    The PM<INF>2.5</INF> SIP Requirements Rule establishes specific 
regulatory requirements for purposes of satisfying the Act's RFP 
requirements and provides related guidance in the preamble to the rule. 
Specifically, under the PM<INF>2.5</INF> SIP Requirements Rule, each 
PM<INF>2.5</INF> attainment plan must contain an RFP analysis that 
includes, at a minimum, the following four components: (1) An 
implementation schedule for control measures; (2) RFP projected 
emissions for direct PM<INF>2.5</INF> and all PM<INF>2.5</INF> 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 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

[[Page 49119]]

attainment year.\163\ States should estimate the RFP projected 
emissions for each quantitative milestone year by sector on a 
pollutant-by-pollutant basis.\164\ In an area that cannot practicably 
attain the PM<INF>2.5</INF> standard by the applicable Moderate area 
attainment date, full implementation of a control strategy that 
satisfies the Moderate area control requirements represents RFP towards 
attainment.\165\
---------------------------------------------------------------------------

    \163\ 40 CFR 51.1012(a).
    \164\ 81 FR 58010, 58056.
    \165\ Id. at 58056, 58057.
---------------------------------------------------------------------------

    Section 189(c) requires that attainment plans include quantitative 
milestones that demonstrate RFP. The purpose of the quantitative 
milestones is to allow for periodic evaluation of the area's progress 
towards attainment of the 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 will 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 emission controls in the attainment plan 
and the requirement to quantify those required emission reductions. The 
CAA also requires states to submit milestone reports (due 90 days after 
each milestone), and these reports should include calculations and any 
assumptions made by the state concerning how RFP has been met, e.g., 
through quantification of emission reductions to date.\166\ The Act 
requires states to include RFP and quantitative milestones even for 
areas that cannot practicably attain.
---------------------------------------------------------------------------

    \166\ 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.\167\ 
Consistent with this longstanding interpretation of the Act, the 
PM<INF>2.5</INF> SIP Requirements Rule requires that each plan for a 
Moderate PM<INF>2.5</INF> nonattainment area contain quantitative 
milestones to be achieved no later than milestone dates 4.5 years and 
7.5 years from the date of designation of the area.\168\ Because the 
EPA designated the SJV nonattainment for the 2012 PM<INF>2.5</INF> 
NAAQS effective April 15, 2015,\169\ the applicable quantitative 
milestone dates for purposes of this NAAQS in the SJV are October 15, 
2019, and October 15, 2022. Following reclassification of the SJV as 
Serious for the 2012 PM<INF>2.5</INF> standard, later milestones would 
be addressed by the Serious area plan.\170\
---------------------------------------------------------------------------

    \167\ General Preamble, 13539 and General Preamble Addendum, 
42016.
    \168\ 40 CFR 51.1013(a)(1).
    \169\ 80 FR 2206.
    \170\ General Preamble Addendum, 42016.
---------------------------------------------------------------------------

2. Summary of State's Reasonable Further Progress Demonstrations and 
Quantitative Milestones
a. 2016 PM<INF>2.5</INF> Plan RFP and Quantitative Milestones
    The RFP demonstration and quantitative milestones are discussed in 
section 3.5 of the 2016 PM<INF>2.5</INF> Plan. The plan estimates that 
emissions of direct PM<INF>2.5</INF> and NO<INF>X</INF> will generally 
decline from the 2013 base year and states that emissions of each of 
these pollutants will remain at or below the levels needed to show 
``generally linear progress'' through 2022, the Moderate area post-
attainment milestone year for the 2012 PM<INF>2.5</INF> NAAQS.\171\ The 
Plan's emissions inventory shows that direct PM<INF>2.5</INF> and 
NO<INF>X</INF> are emitted by a large number and range of sources in 
the SJV and that the emission reductions needed for these pollutants 
are inventory-wide.\172\ The Plan states that all RACM and RACT for 
stationary, area, and mobile sources have been identified and adopted, 
and identifies the District rules achieving emission reductions post-
2013 in Table 3-2 and CARB regulations contributing to attainment in 
Table 3-3.
---------------------------------------------------------------------------

    \171\ 2016 PM<INF>2.5</INF> Plan, Table 3-6. We note that 
Appendix B (``Emissions Inventory'') of the plan indicates that 
emissions of ammonia, SO<INF>X</INF>, and VOC will also generally 
decline from the 2013 base year, but the RFP plan does not address 
these three precursor pollutants given the State's conclusion that 
they do not contribute significantly to PM<INF>2.5</INF> levels that 
exceed the 2012 PM<INF>2.5</INF> NAAQS in the SJV. 2016 
PM<INF>2.5</INF> Plan, 3-10.
    \172\ 2016 PM<INF>2.5</INF> Plan, App. B.
---------------------------------------------------------------------------

    Table 3-6 of the 2016 PM<INF>2.5</INF> Plan presents target RFP 
emission levels, based on linear emission reductions from 2013 through 
2022, and the RFP projected emissions, based on the plan's baseline 
emissions inventory and control strategy (i.e., RACM/RACT and 
additional reasonable measures) for each quantitative milestone year 
(2019 and 2022).\173\ We reproduce Table 3-6, in part, along with the 
plan's 2013 base year inventory from Table 3-5, in Table 4. Based on 
these analyses, the District and CARB conclude that their adopted 
control strategy will achieve sufficient reductions in emissions of 
direct PM<INF>2.5</INF> and NO<INF>X</INF> to result in emission levels 
at or below the RFP and quantitative milestone target emission levels 
for 2019 and 2022.\174\
---------------------------------------------------------------------------

    \173\ Table 3-6 identifies only emission levels for milestone 
years that must be addressed by the Moderate area plan (i.e., 2019 
and 2022).
    \174\ 2016 PM<INF>2.5</INF> Plan, 3-10, and CARB 2016 Staff 
Report, 13.

                     Table 4--2016 PM2.5 Plan: Annual PM2.5 Emissions Inventory for Base Year and Moderate Area Plan Milestone Years
                                                                  [Annual average, tpd]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                   2019 RFP target   2019 projected    2022 RFP target   2022 projected
                           Pollutant                              2013 baseline    emissions level   emissions level   emissions level   emissions level
--------------------------------------------------------------------------------------------------------------------------------------------------------
Direct PM2.5..................................................              63.4              60.8              60.2              59.5              59.5
NOX...........................................................             318.1             229.5             219.4             185.2             185.2
--------------------------------------------------------------------------------------------------------------------------------------------------------
Source: 2016 PM2.5 Plan, tables 3-5 and 3-6. We corrected the 2019 RFP Target Emissions Level for NOX in Table 3-6 to reflect the value in Table 3-5
  that was transcribed incorrectly as 229.1 tpd.

    The 2016 PM<INF>2.5</INF> Plan documents the State's conclusion 
that all RACM/RACT and additional reasonable measures for these 
pollutants are being implemented as expeditiously as practicable and 
identifies projected levels of direct PM<INF>2.5</INF> and 
NO<INF>X</INF> emissions that reflect full implementation of the State, 
District, and SJV MPOs' RACM/RACT and additional reasonable measure 
control strategy for these pollutants.\175\ The control strategy that 
provides the basis for these emission projections is described in 
attachments 1 and 2 of the 2016 PM<INF>2.5</INF> Plan.
---------------------------------------------------------------------------

    \175\ 2016 PM<INF>2.5</INF> Plan, 3-5 through 3-7; see also 
evaluation of RACM/RACT and additional reasonable control measures 
in section IV.D of this proposed rule.

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

[[Page 49120]]

    For quantitative milestones, the 2016 PM<INF>2.5</INF> Plan 
identifies 2019 and 2022 as the applicable milestone years and includes 
milestones to track the State's and District's implementation of 
control measures and to document updated emissions data.\176\ For 2019, 
the milestone includes a ``list of measures in the SIP control strategy 
and key implementation requirements,'' including compliance milestones 
in CARB's Truck and Bus Regulation and in the District's Rule 4901 on 
residential wood burning. For 2022, the milestone includes a ``list of 
measures in the SIP control strategy and key implementation 
requirements,'' including compliance milestones in CARB's Truck and Bus 
Regulation.
---------------------------------------------------------------------------

    \176\ 2016 PM<INF>2.5</INF> Plan, 3-13.
---------------------------------------------------------------------------

b. 2018 PM<INF>2.5</INF> Plan RFP and Quantitative Milestones
    Appendix H of the 2018 PM<INF>2.5</INF> Plan provides the State's 
updated RFP demonstration and quantitative milestones, based on updated 
data (e.g., updated emissions inventories, as discussed in section IV.A 
of this proposed rule) for the 2019 and 2022 milestone years. 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.\177\ Given the State's conclusions that ammonia, 
SO<INF>X</INF>, and VOC emissions do not contribute significantly to 
PM<INF>2.5</INF> levels that exceed the 2012 PM<INF>2.5</INF> 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 
PM<INF>2.5</INF> and NO<INF>X</INF>.\178\ Similarly, the State 
developed quantitative milestones based upon the 2018 PM<INF>2.5</INF> 
Plan's strategy for reducing emissions of direct PM<INF>2.5</INF> and 
NO<INF>X</INF>.\179\
---------------------------------------------------------------------------

    \177\ Appendix H to 2018 PM<INF>2.5</INF> 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 PM<INF>2.5</INF> 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.
    \178\ 2018 PM<INF>2.5</INF> Plan, App. H, H-1.
    \179\ Id. at H-23 to H-24 (for State milestones) and H-20 to H-
21 (for District milestones).
---------------------------------------------------------------------------

    Like the 2016 PM<INF>2.5</INF> Plan, the 2018 PM<INF>2.5</INF> Plan 
estimates that emissions of direct PM<INF>2.5</INF> and NO<INF>X</INF> 
will generally decline from the 2013 base year to the 2022 RFP 
milestone year and beyond, and that direct PM<INF>2.5</INF> and 
NO<INF>X</INF> are emitted by a large number and range of sources in 
the SJV. The 2018 PM<INF>2.5</INF> Plan relies on the same set of 
identified control measures as the 2016 PM<INF>2.5</INF> Plan to 
demonstrate RFP through 2022, i.e., the baseline measures reflected in 
each plan's emissions inventory.\180\
---------------------------------------------------------------------------

    \180\ 2018 PM<INF>2.5</INF> Plan, App. H, H-4 to H-15.
---------------------------------------------------------------------------

    In addition to these baseline measures, the 2018 PM<INF>2.5</INF> 
Plan's control strategy includes specific control measure commitments 
for purposes of attaining the 2012 PM<INF>2.5</INF> NAAQS by 2025, 
including commitments by the State and 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.\181\ Although the attainment demonstration 
does not rely on these control measure commitments for emission 
reductions until 2024,\182\ the RFP and quantitative milestone elements 
of the 2018 PM<INF>2.5</INF> Plan rely on these control measure 
commitments to demonstrate that the plan requires RFP toward 
attainment.\183\
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    \181\ CARB Resolution 18-49 (October 25, 2018), 5; 2018 
PM<INF>2.5</INF> Plan, Ch. 4, Table 4-8; email dated November 12, 
2019, from Sylvia Vanderspek, CARB to Anita Lee, EPA Region IX, 
``RE: SJV PM<INF>2.5</INF> information'' (attaching ``Valley State 
SIP Strategy Progress''); CARB 2018 Staff Report, 14; SJVUAPCD 
Governing Board Resolution 18-11-16 (November 15, 2018), 10-11; 2018 
PM<INF>2.5</INF> 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 
PM<INF>2.5</INF> plan'' (attaching ``District Progress In 
Implementing Commitments with 2018 PM<INF>2.5</INF> Plan'').
    \182\ 2018 PM<INF>2.5</INF> Plan, Ch. 4, Table 4-3 (``Emission 
Reductions from District Measures'') and Table 4-9 (``San Joaquin 
Valley Expected Emission Reductions from State Measures'').
    \183\ 2018 PM<INF>2.5</INF> 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).
---------------------------------------------------------------------------

    Specifically, for the 2019 milestone year, Appendix H of the 2018 
PM<INF>2.5</INF> Plan describes the District's quantitative milestone 
as a report on ``[t]he status of SIP measures adopted between 2017 and 
2019 as per the schedule included in the adopted Plan, including 
Residential Wood Burning Strategy and Commercial Under-Fired 
Charbroiler incentive-based strategy.'' \184\ The schedule for 
development of new or revised SIP measures is in Chapter 4 of the 2018 
PM<INF>2.5</INF> Plan and identifies an ``action date'' between 2017 
and 2019 for one District measure: ``Rule 4901, Wood Burning Fireplaces 
and Wood Burning Heaters (Hot-spot Strategy).'' \185\
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    \184\ 2018 PM<INF>2.5</INF> Plan, App. H, H-20.
    \185\ Id. at 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 
PM<INF>2.5</INF> plan'' (attaching ``District Progress In 
Implementing Commitments with 2018 PM<INF>2.5</INF> 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 milestones as a report on 
three measure-specific milestones: (1) Actions taken between 2017 and 
2019 to implement the Truck and Bus Regulation that required 
particulate filters and cleaner engine standards on existing heavy-duty 
diesel trucks and buses in California; (2) implementation of the ``In-
Use Off-Road Diesel-Fueled Fleets Regulation'' (the ``Off-Road 
Regulation'') that began in 2014 for large fleets and in 2017 for 
medium fleets and limited emissions from existing off-road diesel 
vehicles operated in California; and (3) the ``status of SIP measures 
adopted between 2017 and 2019, including the California Low-NOX Engine 
Standard for new on-road heavy-duty engines used in medium- and heavy-
duty trucks purchased in California.'' \186\ The schedule for 
development of new or revised CARB measures is in Chapter 4 of the 2018 
PM<INF>2.5</INF> Plan and identifies ``action'' dates between 2017 and 
2019 for eight CARB measures: ``Lower Opacity Limits for Heavy-Duty 
Vehicles,'' ``Amended Warranty Requirements for Heavy-Duty Vehicles,'' 
the ``Low-NO<INF>X</INF> Engine Standard,'' ``Innovative Clean 
Transit,'' ``Advanced Clean Local Trucks (Last Mile Delivery),'' 
``Zero-Emission Airport Shuttle Buses,'' ``Zero-Emission Airport Ground 
Support Equipment,'' and ``Transport Refrigeration Units Used for Cold 
Storage.'' \187\
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    \186\ Id. at H-23.
    \187\ Id. at 4-28 (Table 4-8). See also email dated November 12, 
2019, from Sylvia Vanderspek, CARB to Anita Lee, EPA Region IX, 
``RE: SJV PM<INF>2.5</INF> 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 2022 milestone year, Appendix H of the 2018 
PM<INF>2.5</INF> 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.'' \188\ The schedule for 
development of new or revised SIP measures in the 2018 PM<INF>2.5</INF> 
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,

[[Page 49121]]

Glass Melting Furnaces.'' \189\ 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.'' The schedule for development of new or 
revised CARB measures in the 2018 PM<INF>2.5</INF> Plan identifies 
``action'' dates between 2019 and 2022 for 13 CARB measures listed in 
Table 4-8 of Chapter 4, including, for example, the ``Heavy-Duty 
Vehicle Inspection and Maintenance Program,'' ``Small Off-Road 
Engines,'' and the ``Low-Emission Diesel Fuel Requirement.'' \190\
---------------------------------------------------------------------------

    \188\ 2018 PM<INF>2.5</INF> Plan, App. H, H-20.
    \189\ Id. at 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 
PM<INF>2.5</INF> plan'' (attaching ``District Progress In 
Implementing Commitments with 2018 PM<INF>2.5</INF> 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).
    \190\ Id. at 4-28 (Table 4-8). See also email dated November 12, 
2019, from Sylvia Vanderspek, CARB to Anita Lee, EPA Region IX, 
``RE: SJV PM<INF>2.5</INF> 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).
---------------------------------------------------------------------------

    Appendix H of the 2018 PM<INF>2.5</INF> Plan identifies October 15, 
2019, and October 15, 2022, as applicable milestone dates for the 2012 
PM<INF>2.5</INF> NAAQS.\191\ Table H-11 in Appendix H presents the RFP 
projected emissions levels for 2019 and 2022, based on the plan's 
emissions inventory and baseline measures. We reproduce Table H-11, in 
part, along with the 2018 PM<INF>2.5</INF> Plan's base year inventory 
for 2013 from Appendix B, in Table 5.
---------------------------------------------------------------------------

    \191\ 2018 PM<INF>2.5</INF> Plan, App. H, Table H-12.

                     Table 5--2018 PM2.5 Plan: Annual PM2.5 Emissions Inventory for Base Year and Moderate Area Plan Milestone Years
                                                                  [Annual average, tpd]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                   2019 RFP target
                           Pollutant                             2013 Base year    emissions level   2019 projected    2022 RFP target   2022 projected
                                                                                          a          emissions level   emissions level   emissions level
--------------------------------------------------------------------------------------------------------------------------------------------------------
Direct PM2.5..................................................              62.5              59.2              59.2              58.4              58.4
NOX...........................................................             317.2             214.5             214.5             179.8             179.8
--------------------------------------------------------------------------------------------------------------------------------------------------------
Source: 2018 PM2.5 Plan, App. B, tables B-1 and B-2, and App. H, Table H-11.

    The majority of the NO<INF>X</INF> and PM<INF>2.5</INF> reductions 
from 2013 to 2019 and 2022 result from CARB's current mobile source 
control program, which provides significant ongoing reductions in 
emissions of direct PM<INF>2.5</INF> and NO<INF>X</INF> from on-road 
and non-road mobile sources, such as light duty vehicles, heavy-duty 
trucks and buses, non-road equipment, and fuels. The District has also 
adopted numerous stationary and area source rules for direct 
PM<INF>2.5</INF> and NO<INF>X</INF> emission sources that are projected 
to contribute to RFP towards attainment of the PM<INF>2.5</INF> 
standards. These include control measures for stationary internal 
combustion engines, residential fireplaces and woodstoves, glass 
manufacturing facilities, agricultural burning sources, and various 
sizes of boilers, steam generators, and process heaters used in 
industrial operations. CARB's mobile source BACM and MSM analysis in 
Appendix D of the 2018 PM<INF>2.5</INF> Plan and the District's 
stationary and area source BACM and MSM analysis in Appendix C of the 
2018 PM<INF>2.5</INF> Plan provide a more comprehensive overview of 
each of these programs and regulations, among many others.\192\
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    \192\ 2018 PM<INF>2.5</INF> Plan, App. D, Ch. IV, and App. C.
---------------------------------------------------------------------------

3. EPA Evaluation and Proposed Action
a. Reasonable Further Progress
    The EPA has evaluated the RFP demonstrations in the 2016 
PM<INF>2.5</INF> Plan and 2018 PM<INF>2.5</INF> Plan (Appendix H) and 
proposes to find that they satisfy the statutory and regulatory 
requirements for RFP. Because the RFP demonstration in Appendix H of 
the 2018 PM<INF>2.5</INF> Plan is based on updated emissions data and 
updated information about the control strategies being implemented in 
the SJV, we focus our evaluation on Appendix H of the 2018 
PM<INF>2.5</INF> Plan.
    First, the 2016 PM<INF>2.5</INF> Plan and 2018 PM<INF>2.5</INF> 
Plan document the State's, District's, and MPOs' conclusions that they 
are implementing all RACM/RACT and additional reasonable measures for 
direct PM<INF>2.5</INF> and NO<INF>X</INF> emissions in the SJV as 
expeditiously as practicable.\193\ The 2018 PM<INF>2.5</INF> Plan also 
identifies the State's and District's schedules for developing and 
proposing certain new or revised control measures listed in their 
respective control measure commitments. These schedules are found in 
tables 4-4, 4-5, and 4-8 of the 2018 PM<INF>2.5</INF> Plan and in Table 
H-2 of Appendix H.
---------------------------------------------------------------------------

    \193\ The RACM/RACT and additional reasonable measures control 
strategy that provides the basis for the RFP demonstration is 
described in attachments 1 and 2 of the 2016 PM<INF>2.5</INF> Plan.
---------------------------------------------------------------------------

    Second, the RFP demonstration contains projected emission levels 
for direct PM<INF>2.5</INF> and NO<INF>X</INF> for each applicable 
milestone year. These projections are based on continued implementation 
of the existing control measures in the area (i.e., baseline measures) 
and reflect full implementation of the State, District, and MPOs' RACM/
RACT and additional reasonable measures control strategy for these 
pollutants.
    As shown in tables 4 and 5 of this proposed rule, the projected RFP 
emission levels in each plan for 2019 and 2022 are equal to the target 
RFP emission levels in 2019 and 2022, respectively. We note that the 
2013 base year emissions in the 2018 PM<INF>2.5</INF> Plan's emissions 
inventory are 0.9 tpd lower for both direct PM<INF>2.5</INF> and 
NO<INF>X</INF> compared to the base year emissions in the 2016 
PM<INF>2.5</INF> Plan's emissions inventory, and that the 2018 
PM<INF>2.5</INF> Plan's projected RFP emission levels for the 2019 and 
2022 milestone years represent emission reductions that exceed those of 
the 2016 PM<INF>2.5</INF> Plan's projected RFP levels by 0.1 tpd direct 
PM<INF>2.5</INF> and 4.0 tpd NO<INF>X</INF> in 2019, and by 0.2 tpd 
direct PM<INF>2.5</INF> and 4.5 tpd NO<INF>X</INF> in 2022. In other 
words, the 2018 PM<INF>2.5</INF> Plan's RFP demonstration indicates a 
slightly faster pace of emission reductions relative to those in the 
2016 PM<INF>2.5</INF> Plan's RFP demonstration, and thus represents a 
slightly more stringent RFP demonstration than that in the 2016

[[Page 49122]]

PM<INF>2.5</INF> Plan. These projected emissions levels demonstrate 
that the RACM/RACT and additional reasonable measures control strategy 
in the 2016 PM<INF>2.5</INF> Plan will achieve RFP toward attainment.
    Finally, the RFP demonstration shows that overall pollutant 
emissions in each milestone year will be at levels that reflect 
generally linear progress toward attainment. The RFP target emissions 
levels for 2019 and 2022 identified in both the 2016 PM<INF>2.5</INF> 
Plan and the 2018 PM<INF>2.5</INF> Plan reflect consistent progress in 
emission reductions from the 2013 base year to the 2022 post-attainment 
milestone year for the 2012 PM<INF>2.5</INF> NAAQS, based on the 
implementation of the RACT/RACT and additional reasonable measures 
control strategy.
    For these reasons, we propose to determine that the 2016 
PM<INF>2.5</INF> Plan, as revised and supplemented by Appendix H of the 
2018 PM<INF>2.5</INF> Plan, satisfies the requirements for RFP in CAA 
section 172(c)(2) and 40 CFR 51.1012 for the 2012 PM<INF>2.5</INF> 
NAAQS in the SJV.
b. Quantitative Milestones
    The 2016 PM<INF>2.5</INF> Plan identifies the appropriate years 
(2019 and 2022) for quantitative milestones and Appendix H of the 2018 
PM<INF>2.5</INF> Plan identifies specific quantitative milestone dates 
(i.e., October 15, 2019, and October 15, 2022) that are consistent with 
the requirements of 40 CFR 51.1013(a)(4). Both plans also identify the 
target emission levels for direct PM<INF>2.5</INF> and NO<INF>X</INF> 
to be achieved by these milestone dates through implementation of the 
control strategy. Finally, Appendix H of the 2018 PM<INF>2.5</INF> Plan 
identifies commitments by the State and the District to develop and 
propose new or revised control measures on a fixed timeframe, for 
purposes of attaining the 2012 PM<INF>2.5</INF> NAAQS as expeditiously 
as practicable. These target emission levels and associated control 
requirements, together with the State's and District's commitments to 
develop and propose new or revised control measures on a fixed 
timeframe, provide for objective evaluation of the area's progress 
towards attainment of the 2012 PM<INF>2.5</INF> NAAQS.
    The State's quantitative milestones in Appendix H are to implement 
specific baseline measures identified in the plan (i.e., the Truck and 
Bus Regulation and the Off-Road Regulation) and to develop and propose 
several new or revised measures listed in the State's control measure 
commitments that apply to heavy-duty trucks and buses and non-road 
equipment sources.\194\ These commitments to develop and propose 
additional direct PM<INF>2.5</INF> and NO<INF>X</INF> control measures 
for mobile sources are part of CARB's strategy for attaining the 2012 
PM<INF>2.5</INF> NAAQS in the SJV. Similarly, the District's 
quantitative milestones in Appendix H are to develop and propose 
several new or revised 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. These commitments to develop and propose 
additional direct PM<INF>2.5</INF> and NO<INF>X</INF> control measures 
for stationary and area sources are part of the District's strategy for 
attaining the 2012 PM<INF>2.5</INF> NAAQS in the SJV. Thus, the State's 
and District's obligations to implement the identified baseline control 
measures and to fulfil their respective commitments to develop and 
propose new or revised control measures for purposes of attaining the 
2012 PM<INF>2.5</INF> NAAQS provide objective means for evaluating the 
SJV's progress toward timely attainment.
---------------------------------------------------------------------------

    \194\ The EPA is excluding the ``Advanced Clean Cars 2'' measure 
from the milestones because this measure is scheduled for 
implementation in 2026, well after both the 2022 post-attainment RFP 
milestone year and the projected 2025 attainment year for the 2012 
PM<INF>2.5</INF> NAAQS in the 2018 PM<INF>2.5</INF> Plan. Valley 
State SIP Strategy, Table 7.
---------------------------------------------------------------------------

    For these reasons, we propose to determine that the 2016 
PM<INF>2.5</INF> Plan, as revised and supplemented by Appendix H of the 
2018 PM<INF>2.5</INF> Plan, satisfies the requirements for quantitative 
milestones in CAA section 189(c) and 40 CFR 51.1013 for the 2012 
PM<INF>2.5</INF> NAAQS in the SJV.
    We note that on January 13, 2020, CARB submitted the SJV ``2019 
Quantitative Milestone Report for the 2012 PM<INF>2.5</INF> NAAQS'' 
(``2019 QM Report'') to the EPA.\195\ The EPA is currently reviewing 
the SJV 2019 QM Report and will determine, as part of its action on the 
submitted report, whether the State and District have met their 
identified quantitative milestones for 2019.
---------------------------------------------------------------------------

    \195\ 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

    We are presenting our review of the SIP submittals for compliance 
with contingency measure requirements in two different sections of this 
document. In this section, we present our review of the submittals with 
respect to the contingency measure requirements for the SJV as a 
Moderate area for the 2012 PM<INF>2.5</INF> NAAQS for which the state 
has submitted an impracticability demonstration. In section VII of this 
document, we present our review of the submittals with respect to the 
contingency measure requirements for the SJV for the 2006 
PM<INF>2.5</INF> NAAQS.
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 PM<INF>2.5</INF> 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 SIP; (2) to 
meet any quantitative milestone in the approved SIP; (3) to submit a 
required quantitative milestone report; or (4) to attain the applicable 
PM<INF>2.5</INF> NAAQS by the applicable attainment date.\196\ 
Contingency measures must be fully adopted rules or control measures 
that are ready to be implemented quickly upon failure to meet RFP or 
failure of the area to meet the relevant NAAQS by the applicable 
attainment date.\197\
---------------------------------------------------------------------------

    \196\ 40 CFR 51.1014(a).
    \197\ 81 FR 58010, 58066 and General Preamble Addendum, 42015.
---------------------------------------------------------------------------

    The EPA does not interpret the requirement for contingency measures 
for failing to attain the NAAQS by the applicable attainment date to 
apply to a Moderate area that a state adequately demonstrates cannot 
practicably attain the NAAQS by the statutory attainment date. Rather, 
the EPA believes it is appropriate for the state to identify and adopt 
these contingency measures in a timely way as part of the Serious area 
attainment plan that it will develop once the EPA reclassifies such an 
area. However, if a state with a Moderate area that the EPA has found 
cannot practicably attain the NAAQS by the attainment date fails to 
meet RFP, when reviewed as part of the quantitative milestone either 
4.5 or 7.5 years after designation, then the requirement to implement 
contingency measures would be triggered as required by CAA section 
172(c)(9).\198\
---------------------------------------------------------------------------

    \198\ 81 FR 58010, 58067.
---------------------------------------------------------------------------

    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 level of

[[Page 49123]]

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.\199\
---------------------------------------------------------------------------

    \199\ 81 FR 58010, 58066. See also General Preamble 13512, 
13543-13544, and General Preamble Addendum, 42014-42015.
---------------------------------------------------------------------------

    To satisfy the requirements of 40 CFR 51.1014, the contingency 
measures adopted as part of a PM<INF>2.5</INF> 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). In a 2016 decision 
called Bahr v. EPA (``Bahr''),\200\ the Ninth Circuit Court of Appeals 
rejected the EPA's interpretation of CAA section 172(c)(9) to allow 
approval of already-implemented control measures as contingency 
measures. In Bahr, the Ninth Circuit concluded that 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). To comply with section 172(c)(9), as 
interpreted in the Bahr decision, a state must develop, adopt, and 
submit one or more contingency measures to be triggered upon a failure 
to meet any RFP requirement, failure to meet a quantitative milestone 
requirement, or failure to attain the NAAQS by the applicable 
attainment date regardless of the extent to which already-implemented 
measures would achieve surplus emission reductions beyond those 
necessary to meet RFP or quantitative milestone requirements and beyond 
those predicted to achieve attainment of the NAAQS.
---------------------------------------------------------------------------

    \200\ Bahr v. EPA, 836 F.3d 1218, 1235-1237 (9th Cir. 2016).
---------------------------------------------------------------------------

2. Summary of State's Contingency Measures
a. 2016 PM<INF>2.5</INF> Plan Contingency Measures
    The 2016 PM<INF>2.5</INF> Plan includes a contingency measure 
element that is intended to address a potential failure to meet RFP 
but, consistent with the plan's demonstration that it is impracticable 
to attain the 2012 PM<INF>2.5</INF> NAAQS by December 31, 2021, that 
does not address a potential failure to attain the NAAQS by the 
applicable attainment date.\201\ Rather, the State and District 
conclude that they intend to identify and adopt contingency measures 
for failure to attain as part of the Serious area attainment plan (and, 
in fact, have done so in the 2018 PM<INF>2.5</INF> Plan). The State and 
District use the plan's RFP analysis through 2022 to calculate the 
amount of direct PM<INF>2.5</INF> and NO<INF>X</INF> emission 
reductions that represents one year's worth of RFP. Specifically, the 
State and District divided the difference in emissions in 2022 and 2013 
by nine to estimate one year's worth of RFP. The 2016 PM<INF>2.5</INF> 
Plan estimates that one year's worth of RFP is 0.4 tpd of direct 
PM<INF>2.5</INF> and 14.8 tpd of NO<INF>X</INF>.\202\ The contingency 
measure element does not address ammonia, SO<INF>X</INF>, and VOC in 
light of the State and District's conclusion that each of these three 
pollutants does not contribute significantly to exceedances of the 2012 
PM<INF>2.5</INF> NAAQS in the SJV. In addition, the contingency measure 
element in the 2016 PM<INF>2.5</INF> Plan only addresses the potential 
failure to meet the 2019 RFP milestone, not the potential failure to 
meet the 2022 RFP milestone.
---------------------------------------------------------------------------

    \201\ 2016 PM<INF>2.5</INF> Plan, 3-13 to 3-17.
    \202\ 2016 PM<INF>2.5</INF> Plan, Table 3-8.
---------------------------------------------------------------------------

    CARB and the District prepared the 2016 PM<INF>2.5</INF> Plan prior 
to the Bahr decision, and thus did not include any contingency measures 
that would only be triggered conditionally and prospectively, upon a 
future failure to meet RFP or other relevant event. Instead, CARB and 
the District relied only on emissions reductions from already-
implemented measures to satisfy the contingency measure requirement. To 
demonstrate sufficient reductions for contingency purposes, the 2016 
PM<INF>2.5</INF> Plan relies on three types of emission reductions: (1) 
0.6 tpd direct PM<INF>2.5</INF> and 9.7 tpd NO<INF>X</INF> emission 
reductions that are surplus to those needed by 2019 to meet that year's 
linear RFP target emissions, (2) 0.3 tpd NO<INF>X</INF> emission 
reductions from the January 2015 amendment to Rule 4905 (``Natural Gas-
Fired, Fan-Type Central Furnaces'') as being surplus to those captured 
in the 2016 PM<INF>2.5</INF> Plan's emissions inventory, and (3) 3.0 
tpd NO<INF>X</INF> of incentive-based emission reductions in 
conjunction with Rule 9610 (``State Implementation Plan Credit for 
Emission Reductions Generated Through Incentive Programs'').\203\
---------------------------------------------------------------------------

    \203\ 2016 PM<INF>2.5</INF> Plan, 3-15 and 3-16. See also 2016 
PM<INF>2.5</INF> Plan, App. C (``SIP Creditable Incentive-Based 
Emission Reductions'').
---------------------------------------------------------------------------

    CARB and the District then established a ratio of 1:8.8 to trade 
direct PM<INF>2.5</INF> emissions for NO<INF>X</INF> emissions based on 
the 2016 PM<INF>2.5</INF> Plan's precursor sensitivity analysis for the 
traditional high design value sites in Bakersfield.\204\ After 
accounting for the 0.4 tpd direct PM<INF>2.5</INF> emission reductions 
that would meet the 2019 RFP target emission reductions, per the 2019 
RFP target emission reductions, the contingency measure element relies 
on this trading ratio to convert 0.2 tpd of additional direct 
PM<INF>2.5</INF> emission reductions in 2019 into 1.8 tpd of 
NO<INF>X</INF> emission reductions equivalent (after rounding to the 
tenths place).\205\ Then, after accounting for NO<INF>X</INF> emission 
reductions that would meet the 2019 RFP target emissions reductions, 
the contingency measure element sums 9.7 tpd of surplus NO<INF>X</INF> 
emission reductions with 0.3 tpd from the 2015 amendment to Rule 4905, 
1.8 tpd from the surplus direct PM<INF>2.5</INF> conversion, and 3.0 
tpd from the incentive-based emission reductions. The sum of these four 
types of reductions equals 14.8 tpd NO<INF>X</INF>, which matches the 
State's estimate of one year's worth of RFP.
---------------------------------------------------------------------------

    \204\ 2016 PM<INF>2.5</INF> Plan, 3-17.
    \205\ Id. at Table 3-7.
---------------------------------------------------------------------------

    Therefore, the 2016 PM<INF>2.5</INF> Plan concludes that these 
emission reductions (equivalent to one year's worth of progress, i.e., 
0.4 tpd direct PM<INF>2.5</INF> and 14.8 tpd NO<INF>X</INF>) are 
sufficient to satisfy the contingency measure requirements for the 2012 
PM<INF>2.5</INF> NAAQS in the SJV.
b. 2018 PM<INF>2.5</INF> Plan Contingency Measures
    The 2018 PM<INF>2.5</INF> Plan addresses the contingency measure 
requirement for the 2012 PM<INF>2.5</INF> NAAQS by reference to the 
contingency measure portion of a 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 
(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

[[Page 49124]]

contingency measures are sufficient.\206\ Recently, CARB withdrew the 
enhanced enforcement contingency measure of the December 2018 SIP 
submission as it pertained to the 2012 PM<INF>2.5</INF> NAAQS in the 
SJV.\207\ In addition, the 2018 PM<INF>2.5</INF> Plan does not include 
updated emissions estimates for the years following the 2019 and 2022 
RFP milestone years with which to evaluate the sufficiency of 
contingency measure intended to address the applicable Moderate area 
requirements for the 2012 PM<INF>2.5</INF> NAAQS. Rather, with respect 
to the 2012 PM<INF>2.5</INF> NAAQS, the contingency measure element of 
the 2018 PM<INF>2.5</INF> Plan only includes estimates for the year 
(2026) following the Serious area attainment year (2025), and thus, 
these estimates are not relevant for evaluating the sufficiency of 
contingency measures submitted to comply with the Moderate area 
requirements for the 2012 PM<INF>2.5</INF> NAAQS.
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    \206\ 2018 PM<INF>2.5</INF> Plan, App. H (revised February 11, 
2020), H-24 to H-26.
    \207\ Letter dated March 19, 2021, from Richard W. Corey, 
Executive Officer, CARB, to Deborah Jordan, Acting Regional 
Administrator, EPA Region IX, with enclosures.
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    Accordingly, we have evaluated the relevant portions of the 2018 
PM<INF>2.5</INF> Plan and District Rule 4901 (specifically, section 
5.7.3 of Rule 4901), and the contingency measure element in the 2016 
PM<INF>2.5</INF> Plan as discussed above, for compliance with the 
applicable requirements for Moderate areas for the 2012 
PM<INF>2.5</INF> NAAQS. However, while the 2018 PM<INF>2.5</INF> Plan 
does not provide updated emissions estimates for the years following 
the 2019 and 2022 RFP milestone years, the updated emission estimates 
in the 2018 PM<INF>2.5</INF> Plan do provide the basis for an updated 
estimate of one year's worth of RFP for the purposes of evaluating the 
sufficiency of contingency measures to meet the applicable Moderate 
area requirements for the 2012 PM<INF>2.5</INF> NAAQS. The updated 
estimates of emissions one year's worth of RFP based on the updated 
emissions estimates in the 2018 PM<INF>2.5</INF> Plan are 0.5 tpd 
direct PM<INF>2.5</INF> and 15.3 tpd NO<INF>X</INF>.\208\ This is 
slightly more reductions than the 0.4 tpd direct PM<INF>2.5</INF> and 
14.8 tpd NO<INF>X</INF> emission reductions estimated as one year's RFP 
within the 2016 PM<INF>2.5</INF> Plan, consistent with the slightly 
faster pace of emission reductions reflected in the 2018 
PM<INF>2.5</INF> Plan and discussed in section IV.G.3 of this proposed 
rule.
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    \208\ The estimate of one year's RFP is based on difference 
between the annual average base year (2013) emissions and the 
corresponding emissions in the 2022 RFP milestone year, per Appendix 
B of the 2018 PM<INF>2.5</INF> Plan, divided by nine (i.e., the 
number of years between 2013 and 2022).
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    With respect to the District contingency measure, the 2018 
PM<INF>2.5</INF> Plan calls for the District to amend District Rule 
4901 (Wood Burning Fireplaces and Wood Burning Heaters) to include a 
requirement in the rule with a trigger that would be activated should 
the EPA issue a final rulemaking that the SJV failed to meet a 
regulatory requirement necessitating implementation of a contingency 
measure. In response to the commitment made in the 2018 
PM<INF>2.5</INF> Plan, in June 2019, the District adopted amendments to 
Rule 4901 including a contingency measure (in section 5.7.3 of the 
amended rule), and, as an attachment to a letter dated July 19, 2019, 
CARB submitted the amended rule to the EPA for approval.\209\ The EPA 
has taken final action to approve amended Rule 4901, but in that 
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.\210\ Rather, we approved the measure into the 
SIP because it strengthened the rule by providing a possibility of 
additional curtailment days, and thus potentially additional emissions 
reductions. We indicated that we would evaluate whether this provision, 
in conjunction with other submitted provisions, meets the statutory and 
regulatory requirements for contingency measures in future actions. In 
this proposal, we are now evaluating District Rule 4901, specifically, 
section 5.7.3, for compliance with the requirements for contingency 
measures for Moderate areas that cannot practicably attain the 2012 
PM<INF>2.5</INF> NAAQS by the applicable Moderate area attainment date.
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    \209\ Letter from Richard W. Corey, Executive Officer, CARB, to 
Mike Stoker, Regional Administrator, EPA Region IX, July 19, 2019.
    \210\ 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).
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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 PM<INF>2.5</INF> concentration was 
forecasted to be between 20-65 [micro]g/m\3\ and imposed a level two 
curtailment when the PM<INF>2.5</INF> concentration was forecasted to 
be above 65 [micro]g/m\3\ or the PM<INF>10</INF> concentration was 
forecasted to be above 135 [micro]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 PM<INF>2.5</INF> threshold for these three 
counties from 20 [micro]g/m\3\ to 12 [micro]g/m\3\, and the level two 
PM<INF>2.5</INF> threshold from 65 [micro]g/m\3\ to 35 [micro]g/m\3\. 
The District did not modify the curtailment thresholds for other 
counties (i.e., Kings, Merced, San Joaquin, Stanislaus, and Tulare 
counties) in the SJV, and those levels remained at 20 [micro]g/m\3\ for 
level one and 65 [micro]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 
PM<INF>2.5</INF> NAAQS by the applicable attainment date, the 
PM<INF>2.5</INF> 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.
3. EPA Evaluation and Proposed Action
    We have evaluated the contingency measure element in the 2016 
PM<INF>2.5</INF> Plan, as amended in the 2018 PM<INF>2.5</INF> Plan, 
and we find that the fact that the element focuses only on direct 
PM<INF>2.5</INF> and NO<INF>X</INF> (and not ammonia, SO<INF>2</INF>, 
and VOC) is acceptable in light of our proposed approval of the 
precursor demonstration in section IV.B of this document.
    PM<INF>2.5</INF> attainment plan SIP submission for Moderate areas 
that cannot practicably attain by the Moderate area attainment date 
must include

[[Page 49125]]

contingency measures for potential failures to meet RFP, submit a 
quantitative milestone report or meet the quantitative milestones 
associated with the period 4.5 and 7.5 years after designation (in this 
case, the 2019 and 2022 RFP milestone years). With respect to both RFP 
milestone years, we find that the contingency measure element is 
inadequate to meet the Moderate area contingency measure requirements 
for several reasons.
    First, the emission reductions relied upon in the contingency 
measure element to show compliance with the contingency measure 
requirement (i.e., those surplus to RFP, reductions from the 2015 
amendments to Rule 4905, and incentive-based emission reductions from 
projects in 2011-2016 in conjunction with District Rule 9610) come from 
measures that are not prospective (i.e., to-be-triggered) but rather 
come from measures that have already been implemented, and thus would 
not constitute contingency measures under CAA section 172(c)(9) 
consistent with the Bahr decision.\211\
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    \211\ We note that the Ninth Circuit's decision in Bahr v. EPA 
was published on September 12, 2016, just three days before the 
SJVUAPCD adopted the 2016 PM<INF>2.5</INF> Plan on September 15, 
2016. Subsequently, the District and CARB addressed the Bahr 
decision within their discussion of contingency measures for the 
Serious area plan for the 2012 PM<INF>2.5</INF> NAAQS in the San 
Joaquin Valley (i.e., the 2018 PM<INF>2.5</INF> Plan).
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    We recognize that the District has taken action to fulfill the 
commitment in the 2018 PM<INF>2.5</INF> Plan to revise District Rule 
4901 to include specific to-be-triggered contingency provisions. 
However, the contingency measure provision (section 5.7.3) added to the 
rule is only triggered by a finding of failure to attain the 
PM<INF>2.5</INF> NAAQS by the applicable attainment date and not by 
failures to meet a quantitative milestone, submit a quantitative 
milestone report, or failure to meet an RFP requirement. Thus, the rule 
does not include contingency provisions to address the types of 
failures that are the triggering events for contingency measures for 
Moderate areas that cannot practicably attain the PM<INF>2.5</INF> 
NAAQS by the applicable attainment date. Therefore, section 5.7.3 of 
District Rule 4901 does not meet the contingency measure requirements 
of CAA section 172(c)(9) and 40 CFR 51.1014 for the SJV with respect to 
Moderate area requirements for the 2012 PM<INF>2.5</INF> NAAQS.
    Second, as a general matter, we find that surplus emissions 
reductions in the years following RFP milestone years can be taken into 
account in determining whether a contingency measure or contingency 
measures are adequate for a given area for a given pollutant 
notwithstanding the fact that the contingency measure or contingency 
measures would not achieve reductions equivalent to one year's worth of 
RFP. However, the contingency measure element in the 2016 
PM<INF>2.5</INF> Plan provides no emissions estimates for the year 
following the 2022 RFP milestone year for such an evaluation. The 
contingency measure element of the nonattainment area plan only 
provides estimates of surplus emissions reductions in 2019.
    Furthermore, with respect to the emissions analysis for 2019, 
neither Rule 9610 (``State Implementation Plan Credit for Emission 
Reductions Generated Through Incentive Programs'') nor the list of Carl 
Moyer incentive projects in Appendix C of the 2016 PM<INF>2.5</INF> 
Plan may be relied upon as a source for surplus emissions reductions 
because Rule 9610 is not an emission reduction measure \212\ and 
because the Carl Moyer incentive projects listed in Appendix C of the 
2016 PM<INF>2.5</INF> Plan do not satisfy CAA requirements for SIP 
emission reduction credit, as interpreted in the EPA's guidance.\213\ 
In addition, the emission reductions that might otherwise be considered 
surplus due to the 2015 adoption of tighter emissions limits in 
District Rule 4905 would not be considered surplus without additional 
documentation because of the option in Rule 4905 to pay mitigation fees 
in lieu of compliance with emissions limits.\214\
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    \212\ 80 FR 19020 (April 9, 2015) (final approval of Rule 9610), 
79 FR 28652 (May 19, 2014) (proposed approval noting that ``[Rule 
9610] does not establish any emission limitation, control measure, 
or other requirement that applies directly to an emission source''), 
and EPA, Region IX Air Division, ``Technical Support Document for 
EPA's Notice of Proposed Rulemaking for the California State 
Implementation Plan, San Joaquin Valley Unified Air Pollution 
Control District's Rule 9610, State Implementation Plan Credit for 
Emission Reductions Generated through Incentive Programs,'' May 
2014, 4-5 (noting that Rule 9610 ``does not apply to any emission 
source and does not directly impact emissions'').
    \213\ The EPA's longstanding position with respect to incentive-
based control measures is that SIP credit may be allowed for such 
measures only where the State submits enforceable mechanisms to 
ensure that the emission reductions necessary to meet applicable CAA 
requirements are achieved--e.g., an enforceable commitment to 
monitor and report on emission reductions achieved and to rectify 
any shortfall in a timely manner. See, e.g., 80 FR 19020, 19026. The 
2016 PM<INF>2.5</INF> Plan does not contain such enforceable 
mechanisms addressing the Carl Moyer projects listed in Appendix C.
    \214\ EPA, Region IX Air Division, ``Technical Support Document 
for EPA's Proposed Rulemaking for the California State 
Implementation Plan (SIP), San Joaquin Valley Unified Air Pollution 
Control District's Rule 4905, Natural Gas-Fired, Fan-Type Central 
Furnaces,'' October 5, 2015, fn. 8. The EPA approved the 2015 
amended version of District Rule 4905 at 81 FR 17390 (March 29, 
2016).
---------------------------------------------------------------------------

    Third, as a general matter, we agree that the use of trading ratios 
established through modeling techniques to convert surplus reductions 
of direct PM<INF>2.5</INF> emissions to equivalent PM<INF>2.5</INF> 
precursor emissions may be appropriate as part of the explanation for 
why a given contingency measure or measures are sufficient in an area 
with respect to a specific NAAQS. In this instance, however, we note 
that reliance on trading surplus direct PM<INF>2.5</INF> reductions for 
NO<INF>X</INF> reductions at a ratio of 1:8.8 may overestimate the 
amount of equivalent NO<INF>X</INF> reductions based on the information 
in the 2018 PM<INF>2.5</INF> Plan. For the 2018 PM<INF>2.5</INF> Plan, 
the State conducted further analysis of the sensitivity of ambient 
PM<INF>2.5</INF> to emission reductions in PM<INF>2.5</INF> precursors, 
as discussed in section IV.I.2 of this proposal. Based on this updated 
analysis for Bakersfield and Fresno sites, the State proposes to use a 
1:6.5 trading ratio between direct PM<INF>2.5</INF> and NO<INF>X</INF> 
for purposes of the 2018 PM<INF>2.5</INF> Plan's MVEBs. This suggests 
that, while for a different CAA purpose (i.e., MVEB rather than 
contingency measures), any excess direct PM<INF>2.5</INF> used for 
evaluation of contingency measures would be equivalent to fewer 
NO<INF>X</INF> emissions reductions than assumed for the 2016 
PM<INF>2.5</INF> Plan.
    Therefore, in light of the deficiencies described in the preceding 
paragraphs, we are proposing to disapprove the contingency measure 
element of the 2016 PM<INF>2.5</INF> Plan, as amended in the 2018 
PM<INF>2.5</INF> Plan, for failure to meet the requirements for 
contingency measures under CAA section 172(c)(9) and 40 CFR 51.1014(a) 
in the SJV with respect to Moderate area requirements for the 2012 
PM<INF>2.5</INF> NAAQS. More specifically, we are proposing to 
disapprove the contingency measure element for failure to provide for 
the implementation of specific measures to be undertaken if the area 
fails, with respect to the 2019 and 2022 RFP milestone years, to meet 
RFP, to submit a quantitative milestone report (2022 RFP milestone year 
only),\215\ or to meet the quantitative milestones and that, once 
triggered, provide sufficient emissions reductions to meet the purposes 
of contingency measures under the CAA and EPA's implementing 
regulations.
---------------------------------------------------------------------------

    \215\ CARB and the District have prepared and submitted the 2019 
quantitative milestone report and we are currently reviewing it for 
adequacy.
---------------------------------------------------------------------------

I. Motor Vehicle Emissions Budgets

1. Requirements for Motor Vehicle Emissions Budgets
    Section 176(c) of the CAA requires federal actions in nonattainment 
and

[[Page 49126]]

maintenance areas to conform to the SIP's goals of eliminating or 
reducing the severity and number of violations of the NAAQS and 
achieving timely attainment of the standards. Conformity to the SIP's 
goals means that such actions will not: (1) Cause or contribute to 
violations of a NAAQS, (2) worsen the severity of an existing 
violation, or (3) delay timely attainment of any NAAQS or any interim 
milestone.
    Actions involving Federal Highway Administration (FHWA) or Federal 
Transit Administration (FTA) funding or approval are subject to the 
EPA's transportation conformity rule, codified at 40 CFR part 93, 
subpart A. Under this rule, MPOs in nonattainment and maintenance areas 
coordinate with state and local air quality and transportation 
agencies, the EPA, the FHWA, and the FTA to demonstrate that an area's 
regional transportation plans and transportation improvement programs 
conform to the applicable SIP. This demonstration is typically done by 
showing that estimated emissions from existing and planned highway and 
transit systems are less than or equal to the MVEBs contained in all 
control strategy SIPs. An attainment, maintenance, or RFP SIP should 
include budgets for the attainment year, each required RFP milestone 
year, and the last year of the maintenance plan, as appropriate. 
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.\216\
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    \216\ 40 CFR 93.118(e)(4)(v).
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    Under the PM<INF>2.5</INF> SIP Requirements Rule, each attainment 
plan submittal for a Moderate PM<INF>2.5</INF> nonattainment area must 
contain quantitative milestones to be achieved no later than 4.5 years 
and 7.5 years after the date the area was designated 
nonattainment.\217\ The second of these milestone dates, October 15, 
2022,\218\ falls after the latest permissible Moderate area attainment 
date for the SJV, which is December 31, 2021. As the EPA explained in 
the preamble to the PM<INF>2.5</INF> SIP Requirements Rule, it is 
important to include a post-attainment year quantitative milestone to 
ensure that, if the area fails to attain by the attainment date, the 
EPA can continue to monitor the area's progress toward attainment while 
the state develops a new attainment plan.\219\ Moderate area plans 
demonstrating that attainment by the Moderate area attainment date is 
impracticable must, therefore, include budgets for both of the 
milestone dates. States that submit impracticability demonstrations for 
Moderate areas under CAA section 189(a)(1)(B)(ii), however, are not 
required to submit budgets for the attainment year because the 
submitted SIP does not demonstrate attainment.\220\
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    \217\ 40 CFR 51.1013(a)(1).
    \218\ Because the SJV was designated nonattainment effective 
April 15, 2015, the first milestone date is October 15, 2019, and 
the second milestone date is October 15, 2022. 80 FR 2206.
    \219\ 81 FR 58010, 58058 and 58063-58064.
    \220\ Id. at 58055.
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    PM<INF>2.5</INF> plans should identify budgets for direct 
PM<INF>2.5</INF>, NO<INF>X</INF>, and all other PM<INF>2.5</INF> 
precursors for which on-road emissions are determined to contribute 
significantly to PM<INF>2.5</INF> levels in the area for each RFP 
milestone year and the attainment year, if the plan demonstrates 
attainment. All direct PM<INF>2.5</INF> SIP budgets should include 
direct PM<INF>2.5</INF> motor vehicle emissions from tailpipes, brake 
wear, and tire wear. With respect to PM<INF>2.5</INF> from re-entrained 
road dust and emissions of VOC, SO<INF>2</INF>, and/or ammonia, the 
transportation conformity provisions of 40 CFR part 93, subpart A, 
apply only if the EPA Regional Administrator or the director of the 
state air agency has made a finding that transportation-related 
emissions of these pollutants within the area are a significant 
contributor to the PM<INF>2.5</INF> 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.\221\ 
Additionally, as the EPA explained in its May 6, 2005 transportation 
conformity rule amendments for the PM<INF>2.5</INF> NAAQS, it is not 
necessary for a SIP to explicitly state that VOC, SO<INF>2</INF>, and/
or ammonia are insignificant precursors. Instead, states should 
consider the on-road contribution of all four precursors to the 
PM<INF>2.5</INF> problem as they develop their SIPs and establish 
emissions budgets for those precursors for which on-road emissions need 
to be addressed in order to attain the PM<INF>2.5</INF> standard as 
expeditiously as practicable. Conformity determinations must address 
all precursors for which the SIP establishes a budget and need not 
address those precursors for which the state has not established a 
budget because the emissions of that precursor are insignificant.\222\
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    \221\ 40 CFR 93.102(b)(3), 93.102(b)(2)(v), and 93.122(f); see 
also transportation conformity rule preambles at 69 FR 40004, 40031-
40036 (July 1, 2004), 70 FR 24280, 24283-24285 (May 6, 2005) and 70 
FR 31354 (June 1, 2005).
    \222\ 70 FR 24280, 24287 (May 6, 2005).
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    By contrast, transportation conformity requirements apply with 
respect to emissions of NO<INF>X</INF> unless both the EPA Regional 
Administrator and the director of the state air agency have made a 
finding that transportation-related emissions of NO<INF>X</INF> within 
the nonattainment area are not a significant contributor to the 
PM<INF>2.5</INF> 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.\223\
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    \223\ 40 CFR 93.102(b)(2)(iv).
---------------------------------------------------------------------------

    The criteria for insignificance determinations are provided in 40 
CFR 93.109(f). In order for a pollutant or precursor to be considered 
an insignificant contributor, 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/
precursor for a NAAQS violation to occur. Insignificance determinations 
are based on factors such as air quality, SIP motor vehicle control 
measures, trends and projections of motor vehicle emissions, and the 
percentage of the total SIP inventory that is comprised of motor 
vehicle emissions. The EPA's rationale for providing for insignificance 
determinations is described in the July 1, 2004, revision to the 
transportation conformity rule.\224\
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    \224\ 69 FR 40004.
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    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 budget during a 
public comment period; and (3) making a finding of adequacy or 
inadequacy. 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)).
    For budgets to be approvable, they must meet, at a minimum, the 
EPA's adequacy criteria (40 CFR 93.118(e)(4)). To meet these 
requirements, the budgets must be consistent with the attainment and 
RFP requirements and reflect all of the motor vehicle control measures

[[Page 49127]]

contained in the attainment and RFP demonstrations.\225\
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    \225\ 40 CFR 93.118(e)(4)(iii), (iv) and (v). For more 
information on the transportation conformity requirements and 
applicable policies on MVEBs, please visit our transportation 
conformity website at: http://www.epa.gov/otaq/stateresources/transconf/index.htm.
---------------------------------------------------------------------------

2. Summary of State's Motor Vehicle Emissions Budgets
    The 2016 PM<INF>2.5</INF> Plan includes budgets for direct 
PM<INF>2.5</INF> and NO<INF>X</INF> for 2019 (RFP milestone year) and 
2022 (post-attainment RFP milestone year) and no other year given the 
plan's demonstration of the impracticability of attaining the 2012 
PM<INF>2.5</INF> NAAQS by 2021.\226\ Similarly, for the Moderate area 
timeframe, the 2018 PM<INF>2.5</INF> Plan includes budgets for direct 
PM<INF>2.5</INF> and NO<INF>X</INF> for 2019 and 2022 RFP milestone 
years.\227\ We consider the 2019 and 2022 RFP milestone budgets from 
the 2018 PM<INF>2.5</INF> Plan as superseding the corresponding budgets 
from the 2016 PM<INF>2.5</INF> Plan.
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    \226\ 2016 PM<INF>2.5</INF> Plan, Table 3-11.
    \227\ 2018 PM<INF>2.5</INF> Plan, App. D, Table 3-3.
---------------------------------------------------------------------------

    The budgets in both the 2016 PM<INF>2.5</INF> Plan and the 2018 
PM<INF>2.5</INF> Plan were calculated using EMFAC2014 and the latest 
modeled vehicle activity data (vehicle miles traveled and speed 
distributions) available at the time of plan development. In the case 
of the 2016 PM<INF>2.5</INF> Plan, vehicle activity data are derived 
from the draft 2017 Federal-Statewide Transportation Improvement 
Program (2017 FSTIP) from each of the SJV's eight MPOs. The 2018 
PM<INF>2.5</INF> Plan budgets are based on updated motor vehicle 
activity data from the most recently amended 2017 FSTIP (as of January 
2018) from each of the SJV's eight MPOs. The budgets reflect annual 
average emissions consistent with the annual averaging period of the 
2012 PM<INF>2.5</INF> NAAQS and the 2018 PM<INF>2.5</INF> Plan's RFP 
demonstration.
    As with the 2016 PM<INF>2.5</INF> Plan, the 2018 PM<INF>2.5</INF> 
Plan includes direct PM<INF>2.5</INF> budgets for tailpipe, brake wear, 
and tire wear emissions, but does not include paved road dust, unpaved 
road dust, and road construction dust emissions. The 2018 
PM<INF>2.5</INF> Plan also includes budgets for NO<INF>X</INF>, as a 
regulated precursor under the plan, but does not include budgets for 
VOC, SO<INF>2</INF>, or ammonia.\228\ The budgets included in the 2018 
PM<INF>2.5</INF> Plan with respect to the Moderate area timeframe are 
shown in Table 6.
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    \228\ 2018 PM<INF>2.5</INF> Plan, App. D, D-121 to D-123.

                    Table 6--2019 and 2022 San Joaquin Valley MVEBs for the 2012 PM2.5 NAAQS
                                              [Annual average, tpd]
----------------------------------------------------------------------------------------------------------------
                                                          2019 (RFP year)           2022 (post-attainment year)
                     County                      ---------------------------------------------------------------
                                                       PM2.5            NOX            PM2.5            NOX
----------------------------------------------------------------------------------------------------------------
Fresno..........................................             0.9            27.6             0.9            21.2
Kern (San Joaquin Valley portion)...............             0.8            25.1             0.8            19.4
Kings...........................................             0.2             5.1             0.2             4.1
Madera..........................................             0.2             4.6             0.2             3.5
Merced..........................................             0.3             9.4             0.3             7.6
San Joaquin.....................................             0.6            12.7             0.6            10.0
Stanislaus......................................             0.4            10.5             0.4             8.1
Tulare..........................................             0.4             9.3             0.4             6.9
----------------------------------------------------------------------------------------------------------------
Source: 2018 PM2.5 Plan, App. D, Table 3-3. Budgets are rounded up to the nearest tenth.

    The 2018 PM<INF>2.5</INF> Plan also includes a proposed trading 
mechanism for transportation conformity analyses that would allow 
future decreases in NO<INF>X</INF> emissions from on-road mobile 
sources to offset any on-road increases in direct PM<INF>2.5</INF> 
emissions. For the 2012 PM<INF>2.5</INF> NAAQS, the State is proposing 
to use the 6.5:1 NO<INF>X</INF>:PM<INF>2.5</INF> ratio. The ratio is 
based on a sensitivity analysis based on a 30% reduction of 
NO<INF>X</INF> or PM<INF>2.5</INF> emissions and the corresponding 
impact on design values at sites in Bakersfield and Fresno (i.e., 
updated analysis relative to the 2008 PM<INF>2.5</INF> Plan for the 
1997 PM<INF>2.5</INF> NAAQS). For the sake of comparison, in approving 
the budgets for the SJV 2008 PM<INF>2.5</INF> Plan for the 1997 
PM<INF>2.5</INF> NAAQS, the EPA approved a trading mechanism for 
transportation conformity analyses that allowed for such one-way trades 
(i.e., only excess NO<INF>X</INF> can be used to offset 
PM<INF>2.5</INF>, not vice versa) at a 9:1 
NO<INF>X</INF>:PM<INF>2.5</INF> ratio.\229\
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    \229\ 76 FR 69896, at 69923 (November 9, 2011).
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    To ensure that the trading mechanism does not affect the ability of 
the SJV to meet the NO<INF>X</INF> budget, the NO<INF>X</INF> emission 
reductions available to supplement the PM<INF>2.5</INF> budget would 
only be those remaining after the NO<INF>X</INF> budget has been 
met.\230\ The Plan also provides that the SJV MPOs shall clearly 
document the calculations used in the trading, along with any 
additional reductions of NO<INF>X</INF> and PM<INF>2.5</INF> emissions 
in the conformity analysis.
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    \230\ 2018 PM<INF>2.5</INF> Plan, App. D, D-126 and D-127.
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    In the submittal letter for the 2018 PM<INF>2.5</INF> 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.\231\
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    \231\ 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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3. EPA Evaluation and Proposed Action
    For the reasons discussed in section IV.F of this proposed rule, we 
are proposing to approve the State's demonstration that it is 
impracticable to attain the 2012 PM<INF>2.5</INF> standard in the SJV 
by the applicable Moderate area attainment date of December 31, 2021, 
and are proposing to reclassify the area as Serious. Accordingly, we 
are proposing action on the Moderate post-attainment year budgets for 
2022 for the 2012 PM<INF>2.5</INF> NAAQS in the SJV. The EPA is not 
reviewing the submitted motor vehicle emissions budgets for 2019 
because that year will not be an applicable conformity analysis year in 
the next conformity analysis for the SJV MPOs. Also, as noted above, we 
consider the 2022 RFP milestone budgets from the 2018 PM<INF>2.5</INF> 
Plan as superseding the corresponding budgets from the 2016 
PM<INF>2.5</INF> Plan and thus are proposing action only on the 
former.\232\
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    \232\ The differences between the two sets of budgets are minor. 
For 2019, there is no difference between the budgets in the 2016 
PM<INF>2.5</INF> Plan and the 2018 PM<INF>2.5</INF> Plan. For 2022, 
there is no difference between the two sets of budgets for direct 
PM<INF>2.5</INF>, and, with the exception of San Joaquin County, the 
difference between the two sets of budgets for NO<INF>X</INF> is 
less than or equal to 0.1 tpd. For San Joaquin County, the 2022 
NO<INF>X</INF> budget is 0.7 tpd higher under the 2018 
PM<INF>2.5</INF> Plan than the corresponding budget from the 2016 
PM<INF>2.5</INF> Plan.
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    The EPA generally first conducts a preliminary review of budgets 
submitted with an attainment or maintenance plan for PM<INF>2.5</INF> 
for

[[Page 49128]]

adequacy, prior to taking action on the plan itself, and did so with 
respect to the PM<INF>2.5</INF> budgets in the 2018 PM<INF>2.5</INF> 
Plan. On June 18, 2019, the EPA announced the availability of the 2018 
PM<INF>2.5</INF> Plan with MVEBs 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.
    The 2018 PM<INF>2.5</INF> Plan establishes budgets for the 2022 RFP 
milestone year for direct PM<INF>2.5</INF> and NO<INF>X</INF>, but not 
for the other PM<INF>2.5</INF> precursor emissions (i.e., VOC, 
SO<INF>2</INF>, and ammonia). We propose to find that it is not 
necessary to establish motor vehicle emissions budgets for 
transportation-related emissions of VOC, SO<INF>2</INF>, and ammonia to 
attain the 2012 annual PM<INF>2.5</INF> NAAQS in the SJV based on our 
proposal to approve the State's demonstration that emissions of VOC, 
SO<INF>2</INF>, and ammonia do not contribute significantly to 
PM<INF>2.5</INF> levels that exceed the 2012 PM<INF>2.5</INF> NAAQS in 
the SJV, as discussed in section IV.B of this proposed rule. Our 
finding in this regard is also supported by information about VOC, 
SO<INF>2</INF>, and ammonia in the 2018 PM<INF>2.5</INF> Plan 
documenting the small contribution by motor vehicles to regional 
precursor inventories and to PM<INF>2.5</INF> design values within the 
SJV.\233\ In addition, based on similar documentation about re-
entrained road dust and construction-related fugitive dust in the 2018 
PM<INF>2.5</INF> Plan and in accordance with 40 CFR 93.102(b)(3) and 
93.122(f), the EPA proposes to find that it is not necessary to include 
re-entrained road dust emissions or road construction dust in the 
direct PM<INF>2.5</INF> budgets for 2012 PM<INF>2.5</INF> NAAQS in the 
SJV.\234\
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    \233\ 2018 PM<INF>2.5</INF> Plan, App. D. pages D-121, D-122 and 
D-123. Motor vehicle emissions of VOC represent approximately 10% of 
the total VOC emissions in the SJV, but VOC controls are generally 
ineffective at reducing ambient PM<INF>2.5</INF> levels. Motor 
vehicle emissions of SO<INF>2</INF> are less than one tpd, and motor 
vehicle emissions of ammonia represent approximately 1% of total 
ammonia emissions in the SJV.
    \234\ Id. Paved and unpaved road dust emissions represent less 
than 17% of the total PM<INF>2.5</INF> emissions in the SJV but 
contribute only approximately 4% to the design values. Construction 
dust emissions are less than 5% of the total PM<INF>2.5</INF> 
emissions in the SJV. In addition, the 2018 PM<INF>2.5</INF> Plan 
does not include additional control measures for these sources.
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    For the reasons discussed in sections IV.G of this proposed rule, 
the EPA proposes to approve the RFP demonstration in the 2018 
PM<INF>2.5</INF> Plan. The 2022 RFP budgets, as shown in Table 6 of 
this proposed rule, are consistent with this demonstration, 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 budgets listed in Table 6. We provide a more detailed 
discussion in the EPA's memo to file regarding MVEB.\235\ We are not 
proposing to approve the 2018 PM<INF>2.5</INF> Plan's budgets that 
pertain solely to the Serious area time frame (i.e., 2025 attainment 
year budget or the post-attainment year 2028 budget for the 2012 
PM<INF>2.5</INF> NAAQS) at this time. The budgets that the EPA is 
proposing to approve relate to the 2012 annual PM<INF>2.5</INF> NAAQS 
only, and our proposed approval does not affect the status of the 
previously-approved MVEBs for the 1997 annual and 24-hour 
PM<INF>2.5</INF> NAAQS and 2006 24-hour PM<INF>2.5</INF> NAAQS and 
related trading mechanisms that remain in effect for that 
PM<INF>2.5</INF> NAAQS.
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    \235\ Memorandum of July 30, 2021, from Rory Mays and Karina 
O'Connor, Air Planning Office, Air and Radiation Division, Region 
IX, EPA, ``EPA Review of 2018 PM<INF>2.5</INF> Plan Transportation 
Conformity Emission Budgets for the 2012 Annual PM<INF>2.5</INF> 
NAAQS (Moderate Area Requirements).''
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    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 PM<INF>2.5</INF> Plan, as allowed for 
under 40 CFR 93.124(b). Furthermore, the trading ratio in the 2018 
PM<INF>2.5</INF> Plan is based on updated air quality modeling and 
analysis relative to the analysis that the 2016 PM<INF>2.5</INF> Plan 
relies on (i.e., analysis and trading ratio in the 2008 
PM<INF>2.5</INF> Plan for the 1997 PM<INF>2.5</INF> NAAQS). The trading 
mechanism in the 2018 PM<INF>2.5</INF> Plan would allow future 
decreases in annual NO<INF>X</INF> emissions from on-road mobile 
sources to offset any on-road increases in annual direct 
PM<INF>2.5</INF> emissions using a 6.5:1 
NO<INF>X</INF>:PM<INF>2.5</INF> ratio for conformity for the 2012 
annual PM<INF>2.5</INF> NAAQS. To ensure that the trading mechanism 
does not affect the ability to meet the NO<INF>X</INF> budget, the plan 
provides that the NO<INF>X</INF> emission reductions available to 
supplement the PM<INF>2.5</INF> budget would only be those remaining 
after the NO<INF>X</INF> 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 
NO<INF>X</INF> and PM<INF>2.5</INF> 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 PM<INF>2.5</INF> Plan and 
finds it is appropriate for transportation conformity purposes in the 
SJV for the 2012 annual PM<INF>2.5</INF> 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 PM<INF>2.5</INF> Plan for the 1997 
PM<INF>2.5</INF> NAAQS \236\ and the 2012 PM<INF>2.5</INF> Plan for the 
2006 24-hour PM<INF>2.5</INF> NAAQS.\237\ The State's approach in the 
previous plans was to model the ambient PM<INF>2.5</INF> effect of 
areawide NO<INF>X</INF> emissions reductions and of areawide direct 
PM<INF>2.5</INF> reductions, and to express the ratio of these modeled 
sensitivities as an interpollutant trading ratio.
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    \236\ 80 FR 1816, 1841 (January 13, 2015) (noting the EPA's 
prior approval of MVEBs for the 1997 annual and 24-hour 
PM<INF>2.5</INF> standards in the 2008 PM<INF>2.5</INF> Plan at 76 
FR 69896).
    \237\ 81 FR 59876 (August 31, 2016).
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    In the updated analysis for the 2018 PM<INF>2.5</INF> 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 
NO<INF>X</INF> and PM<INF>2.5</INF> 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 
NO<INF>X</INF> and PM<INF>2.5</INF> reductions on ambient 24-hour 
concentrations showed NO<INF>X</INF>:PM<INF>2.5</INF> 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.\238\ We find 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 NO<INF>X</INF> for PM<INF>2.5</INF> trading mechanism as 
enforceable components of the transportation conformity program for the 
SJV for the 2012 annual PM<INF>2.5</INF> NAAQS.
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    \238\ 2018 PM<INF>2.5</INF> 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

[[Page 49129]]

SIP revision. As a general matter, such approved budgets cannot be 
superseded 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.\239\
---------------------------------------------------------------------------

    \239\ 40 CFR 93.118(e)(1).
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    In the submittal letter for the 2018 PM<INF>2.5</INF> 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.\240\ The transportation conformity 
rule allows us to limit the approval of budgets.\241\ However, we will 
consider a state's request to limit an approval of its MVEBs only if 
the request includes the following elements: \242\ (1) An 
acknowledgement and explanation as to why the budgets under 
consideration have become outdated or deficient; (2) a commitment to 
update the budgets as part of a comprehensive SIP update; and (3) a 
request that the EPA limit the duration of its approval to the period 
before new budgets have been found to be adequate for transportation 
conformity purposes.
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    \240\ Letter dated May 9, 2019, from Richard W. Corey, Executive 
Officer, CARB, to Mike Stoker, Regional Administrator, EPA Region 
IX, 3.
    \241\ 40 CFR 93.118(e)(1).
    \242\ 67 FR 69141 (November 15, 2002), limiting our prior 
approval of MVEBs in certain California SIPs.
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    CARB's request includes an explanation for why the budgets have 
become, or will become, outdated or deficient. In short, CARB has 
requested that we limit the duration of the approval of the budgets in 
light of the EPA's approval of EMFAC2017, an updated version of the 
EMFAC2014 used for the budgets in the 2018 PM<INF>2.5</INF> Plan.\243\ 
EMFAC2017 updates vehicle mix and emissions data of the previously 
approved version of the EMFAC2014.
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    \243\ On August 15, 2019, the EPA approved and announced the 
availability of EMFAC2017, the latest update to the EMFAC model for 
use by the State and local governments to meet CAA requirements. 84 
FR 41717.
---------------------------------------------------------------------------

    In light of the EPA's approval of EMFAC2017, CARB explains that the 
budgets in the 2018 PM<INF>2.5</INF> Plan, which we are proposing to 
approve in this action, will become outdated and will need to be 
revised using EMFAC2017. In addition, CARB states that, without the 
ability to replace the budgets using the budget adequacy process, the 
benefits of using the updated data may not be realized for a year or 
more after the updated SIP (with the EMFAC2017-derived budgets) is 
submitted, due to the length of the SIP approval process. We find that 
CARB's explanation for limiting the duration of the approval of the 
budgets is appropriate and provides us with a reasonable basis for 
limiting the duration of the approval of the budgets.
    We note that CARB has not committed to update the budgets as part 
of a comprehensive SIP update, but as a practical matter, CARB must 
submit a SIP revision that includes updated demonstrations as well as 
the updated budgets to meet the adequacy criteria in 40 CFR 
93.118(e)(4).\244\ Therefore, we do not need a specific commitment for 
such a plan at this time. For the reasons provided above, and in light 
of CARB's explanation for why the budgets will become outdated and 
should be replaced upon an adequacy finding for updated budgets, we 
propose to limit the duration of our approval of the budgets in the 
2018 PM<INF>2.5</INF> Plan to the period before we find revised budgets 
based on EMFAC2017 to be adequate.
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    \244\ Under 40 CFR 93.118(e)(4), the EPA will not find a budget 
in a submitted SIP to be adequate unless, among other criteria, the 
budgets, when considered together with all other emissions sources, 
are consistent with applicable requirements for RFP and attainment. 
40 CFR 93.118(e)(4)(iv).
---------------------------------------------------------------------------

    Lastly, in section IV.H of this proposed rule, the EPA is proposing 
to disapprove the contingency measure element of the 2016 
PM<INF>2.5</INF> Plan, as amended in the 2018 PM<INF>2.5</INF> Plan, 
with respect to Moderate area requirements for the 2012 
PM<INF>2.5</INF> NAAQS. If the EPA were to finalize the proposed 
disapproval of the 2012 PM<INF>2.5</INF> NAAQS Moderate area 
contingency measure element, the area would be eligible for a 
protective finding under the transportation conformity rule because the 
2016 PM<INF>2.5</INF> Plan and 2018 PM<INF>2.5</INF> Plan reflect 
adopted control measures that fully satisfy the emissions reductions 
requirements for RFP for years 2019 and 2022.\245\
---------------------------------------------------------------------------

    \245\ 40 CFR 93.120(a)(3).
---------------------------------------------------------------------------

V. Reclassification as Serious Nonattainment and Serious Area SIP 
Requirements

A. Reclassification as Serious and Applicable Attainment Date

    Section 188 of the Act outlines the process for classification of 
PM<INF>2.5</INF> nonattainment areas and establishes the applicable 
attainment dates. Under section 188(b)(1) of the Act, the EPA has 
general authority to reclassify at any time before the applicable 
attainment date any area that the EPA determines cannot practicably 
attain the standard by such date. Accordingly, section 188(b)(1) of the 
Act is a general expression of delegated rulemaking authority. In 
addition, subparagraphs (A) and (B) of section 188(b)(1) mandate that 
the EPA reclassify ``appropriate'' PM<INF>10</INF> nonattainment areas 
at specified time frames (i.e., by December 31, 1991, for the initial 
PM<INF>10</INF> nonattainment areas, and within 18 months after the SIP 
submittal due date for subsequent nonattainment areas). These 
subparagraphs do not restrict the EPA's general authority but simply 
specify that, at a minimum, it must be exercised at certain times.\246\
---------------------------------------------------------------------------

    \246\ For a general discussion of the EPA's interpretation of 
the reclassification provisions in section 188(b)(1) of the Act, see 
the General Preamble, 13537-13538.
---------------------------------------------------------------------------

    We have reviewed the air quality modeling and impracticability 
demonstration in the 2016 PM<INF>2.5</INF> Plan, as well as the air 
quality modeling in the 2018 PM<INF>2.5</INF> Plan. Based on our 
review, we agree with the District's conclusion that implementation of 
the State/District's SIP control strategy, including RACM/RACT and 
additional reasonable measures, is insufficient to bring the SJV into 
attainment of the 2012 PM<INF>2.5</INF> NAAQS by the December 31, 2021 
Moderate area attainment deadline. See sections IV.C and IV.F of this 
proposed rule. In addition, we have reviewed recent PM<INF>2.5</INF> 
monitoring data for SJV available in the EPA's Air Quality System (AQS) 
database. These data show that annual PM<INF>2.5</INF> levels in the 
SJV continue to be above 12.0 [micro]g/m\3\, the numerical level of the 
2012 PM<INF>2.5</INF> standard, and the recent trends in the SJV annual 
PM<INF>2.5</INF> levels indicate that the SJV will not attain by the 
end of 2021.\247\
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    \247\ EPA design value workbook dated May 24, 2021, 
``pm25_designvalues_2018_2020_final_05_24_21.xlsx,'' worksheets 
``Table1a'' and ``Table5a,'' and EPA, 2010-2020 AQS Design Value 
Report, AMP480, June 30, 2021.
---------------------------------------------------------------------------

    In accordance with section 188(b)(1) of the Act, the EPA is 
proposing to reclassify the SJV from Moderate to Serious nonattainment 
for the 2012 annual PM<INF>2.5</INF> standard of 12.0 [micro]g/m\3\, 
based on the EPA's determination that the SJV cannot practicably attain 
the standard by the applicable attainment date of December 31, 2021.
    Under section 188(c)(2) of the Act, the attainment date for a 
Serious area ``shall be as expeditiously as practicable but no later 
than the end of the tenth calendar year beginning after the area's 
designation as nonattainment . . .'' The EPA designated the SJV as 
nonattainment for the 2012 PM<INF>2.5</INF> NAAQS effective April 15, 
2015.\248\ Therefore, upon final reclassification of

[[Page 49130]]

the SJV as a Serious nonattainment area, the latest permissible 
attainment date under section 188(c)(2) of the Act, for purposes of the 
2012 PM<INF>2.5</INF> NAAQS in this area, will be December 31, 2025.
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    \248\ 80 FR 2206.
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    Under section 188(e) of the Act, a state may apply to the EPA for a 
single extension of the Serious area attainment date of up to five 
additional years, which the EPA may grant if the state satisfies 
certain statutory conditions. Before the EPA may extend the attainment 
date for a Serious area under section 188(e), the state must: (1) Apply 
for an extension of the attainment date beyond the statutory attainment 
date; (2) demonstrate that attainment by the statutory attainment date 
is impracticable; (3) demonstrate that it has complied with all 
requirements and commitments pertaining to the area in the 
implementation plan; (4) demonstrate to the satisfaction of the 
Administrator that the plan for the area includes the most stringent 
measures that are included in the implementation plan of any state or 
are achieved in practice in any state, and can feasibly be implemented 
in the area; and (5) submit a demonstration of attainment by the most 
expeditious alternative date practicable.\249\
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    \249\ For a discussion of the EPA's interpretation of the 
requirements of section 188(e), see General Preamble Addendum, 
42002; 65 FR 19964 (April 13, 2000) (proposed action on 
PM<INF>10</INF> Plan for Maricopa County, Arizona); 67 FR 48718 
(July 25, 2002) (final action on PM<INF>10</INF> Plan for Maricopa 
County, Arizona); and Vigil v. EPA, 366 F.3d 1025, amended at 381 
F.3d 826 (9th Cir. 2004) (remanding EPA action on PM<INF>10</INF> 
Plan for Maricopa County, Arizona but generally upholding the EPA's 
interpretation of CAA section 188(e)).
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B. Clean Air Act Requirements for Serious Area Plans

    Upon reclassification as a Serious nonattainment area for the 2012 
PM<INF>2.5</INF> NAAQS, California will be required to submit 
additional SIP revisions to satisfy the statutory requirements that 
apply to Serious PM<INF>2.5</INF> nonattainment areas, including the 
requirements of subpart 4 of part D, title I of the Act.
    The Serious area SIP elements that California will be required to 
submit are as follows:
    1. Provisions to assure that BACM,\250\ including BACT for 
stationary sources, for the control of direct PM<INF>2.5</INF> and 
PM<INF>2.5</INF> precursors shall be implemented no later than four 
years after the area is reclassified (CAA section 189(b)(1)(B));
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    \250\ The EPA defines BACM as, among other things, the maximum 
degree of emission 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 and 42014). BACM must be implemented for all 
categories of sources in a Serious PM<INF>2.5</INF> nonattainment 
area unless the State adequately demonstrates that a particular 
source category does not contribute significantly to nonattainment 
of the PM<INF>2.5</INF> standard. (Id. at 42011, 42012).
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    2. a demonstration (including air quality modeling) that the plan 
provides for attainment as expeditiously as practicable but not later 
than December 31, 2025, or where the state is seeking an extension of 
the attainment date under section 188(e), a demonstration that 
attainment by December 31, 2025, is impracticable and that the plan 
provides for attainment by the most expeditious alternative date 
practicable and not later than December 31, 2030 (CAA sections 
189(b)(1)(A), 188(c)(2), and 188(e));
    3. plan provisions that require RFP (CAA section 172(c)(2));
    4. quantitative milestones that are to be achieved every three 
years until the area is redesignated to attainment and that demonstrate 
RFP toward attainment by the applicable date (CAA section 189(c));
    5. provisions to assure that control requirements applicable to 
major stationary sources of PM<INF>2.5</INF> also apply to major 
stationary sources of PM<INF>2.5</INF> precursors, except where the 
state demonstrates to the EPA's satisfaction that such sources do not 
contribute significantly to PM<INF>2.5</INF> levels that exceed the 
standard in the area (CAA section 189(e));
    6. a comprehensive, accurate, current inventory of actual emissions 
from all sources of PM<INF>2.5</INF> and PM<INF>2.5</INF> precursors in 
the area (CAA section 172(c)(3));
    7. contingency measures to be implemented if the area fails to meet 
RFP (including quantitative milestones and related reports) or to 
attain by the applicable attainment date (CAA section 172(c)(9)); and
    8. a revision to the NNSR program to lower the applicable ``major 
stationary source'' \251\ thresholds from 100 tpy to 70 tpy (CAA 
section 189(b)(3)) and to satisfy the subpart 4 control requirements 
for major stationary sources of PM<INF>2.5</INF> precursors (CAA 
section 189(e)).
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    \251\ 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 tpy of PM<INF>10</INF> (CAA 
sections 189(b)(3)).
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    As discussed in section IV.E of this proposed rule, California 
submitted NNSR SIP revisions for the SJV to address the subpart 4 NNSR 
requirements for Serious PM<INF>2.5</INF> nonattainment areas on 
November 20, 2019. The EPA is evaluating this SIP submission and will 
act on it in a separate rulemaking.
    Finally, reclassification of the SJV as Serious nonattainment for 
the 2012 annual PM<INF>2.5</INF> NAAQS would lower the de minimis 
threshold under the CAA's general conformity requirements (40 CFR part 
93, subpart B) from 100 tpy to 70 tpy for PM<INF>2.5</INF> and 
PM<INF>2.5</INF> precursors.\252\ In this case, however, 
reclassification would have no impact on the applicable general 
conformity de minimis thresholds, because the SJV is already subject to 
the 70 tpy de minimis threshold for PM<INF>2.5</INF> and all 
PM<INF>2.5</INF> precursors as a result of the EPA's previous actions 
reclassifying the area as Serious nonattainment for the 1997 annual and 
24-hour PM<INF>2.5</INF> NAAQS and the 2006 24-hour PM<INF>2.5</INF> 
NAAQS.\253\
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    \252\ 40 CFR 93.153(b), 81 FR 58010, 58126.
    \253\ 80 FR 18528 and 81 FR 1514, respectively.
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C. Statutory Deadline for Submission of Serious Area Plan

    When the EPA reclassifies a nonattainment area to a higher 
classification, the CAA sets the parameters for establishing deadlines 
for attainment plan SIP submissions for that higher classification. The 
State has already made submissions intended to address the Serious area 
attainment plan requirements for the 2012 PM<INF>2.5</INF> NAAQS for 
the SJV, yet the EPA reclassification rulemaking must still establish 
the submission deadlines, as discussed in the following paragraphs. 
Among other things, such deadlines make clear the time frame for any 
future SIP submission should the State find the need to withdraw any 
particular element of the Serious area plan requirements (i.e., without 
the submittal of a replacement element meeting the completeness 
criteria).
    For an area reclassified as a Serious nonattainment area before the 
applicable attainment date under CAA section 188(b)(1), section 
189(b)(2) requires the state to submit the required BACM provisions 
``no later than 18 months after reclassification of the area as a 
Serious Area'' and to submit the required attainment demonstration ``no 
later than 4 years after reclassification of the area to Serious.'' 
Section 189(b)(2) establishes outer bounds on the SIP submission 
deadlines as necessary or appropriate to assure consistency among the 
required submissions and to implement the statutory requirements.
    The Act provides the state with up to 18 months after final 
reclassification of an area to Serious to submit the required BACM 
provisions. Because an up-to-date emissions inventory serves as the 
foundation for a state's BACM/BACT determination, the PM<INF>2.5</INF> 
SIP Requirements Rule requires the state to submit the emissions 
inventory required under CAA section 172(c)(3) within 18

[[Page 49131]]

months after the effective date of final reclassification.\254\ 
Similarly, because an effective evaluation of BACM/BACT measures 
requires evaluation of the precursor pollutants that must be controlled 
to provide for expeditious attainment in the area, if the state chooses 
to submit an optional precursor insignificance demonstration to support 
a determination to exclude a PM<INF>2.5</INF> precursor from the 
required control measure evaluations for the area, the EPA requires 
that the state submit any such demonstration by this same date. An 18-
month time frame for submission of these plan elements is consistent 
with both the time frame for submission of BACM/BACT provisions under 
CAA section 189(b)(2) and the time frame for submission of subpart 1 
plan elements under section 172(b) of the Act.\255\
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    \254\ 81 FR 58010, 58077.
    \255\ Section 172(b) requires the EPA to establish, concurrent 
with nonattainment area designations, a schedule extending no later 
than three years from the date of the nonattainment designation for 
states to submit plans or plan revisions meeting the applicable 
requirements of sections 110(a)(2) and 172(c) of the CAA.
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    The PM<INF>2.5</INF> SIP Requirements Rule also establishes a 
specific deadline for submission of the attainment demonstration and 
attainment-related plan elements following discretionary 
reclassification, which is the earlier of four years from the date of 
reclassification, or the end of the eighth calendar year after 
designation.\256\ In this case, the earlier of these two dates will be 
the end of the eighth calendar year after designation--i.e., December 
31, 2023. The attainment-related plan elements required within the same 
timeframe as the attainment demonstration are as follows: (1) The RFP 
demonstration required under section 172(c)(2); (2) the quantitative 
milestones required under section 189(c); (3) any additional control 
measures necessary to meet the requirements of section 172(c)(6); and 
(4) the contingency measures required under section 172(c)(9). Although 
section 189(b)(2) generally provides for up to four years after a 
discretionary reclassification for the state to submit the required 
attainment demonstration, given the timing of this reclassification 
action less than two years before the Moderate area attainment date, it 
is appropriate in this case for the EPA to establish an earlier SIP 
submission deadline to assure timely implementation of the statutory 
requirements.
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    \256\ 81 FR 58010, 58077.
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    Finally, the PM<INF>2.5</INF> SIP Requirements Rule establishes a 
regulatory requirement that the state submit revised NNSR program 
requirements no later than 18 months after final reclassification.\257\ 
The Act does not specify a deadline for the state's submission of SIP 
revisions to meet NNSR program requirements to lower the ``major 
stationary source'' threshold from 100 tpy to 70 tpy (CAA section 
189(b)(3)) and to address the control requirements for major stationary 
sources of PM<INF>2.5</INF> precursors (CAA section 189(e)) \258\ 
following reclassification of a Moderate PM<INF>2.5</INF> nonattainment 
area as Serious nonattainment under subpart 4. Pursuant to the EPA's 
gap-filling authority in CAA section 301(a) and to effectuate the 
statutory control requirements in section 189 of the Act, the 
PM<INF>2.5</INF> SIP Requirements Rule requires the state to submit 
these NNSR SIP revisions, as well as any necessary analysis of and 
additional control requirements for major stationary sources of 
PM<INF>2.5</INF> precursors, no later than 18 months after the 
effective date of final reclassification of the SJV as Serious 
nonattainment for the 2012 PM<INF>2.5</INF> standard. This due date 
will ensure that necessary control requirements for major sources are 
established in advance of the required attainment demonstration. An 18-
month timeframe for submission of the NNSR SIP revisions also aligns 
with the statutory deadline for submission of BACM and BACT provisions 
and the broader analysis of PM<INF>2.5</INF> precursors for potential 
controls on existing sources in the area.
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    \257\ Id. at 58078.
    \258\ Section 189(e) requires that the control requirements 
applicable to major stationary sources of PM<INF>2.5</INF> also 
apply to major stationary sources of PM<INF>2.5</INF> precursors, 
except where the state demonstrates to the EPA's satisfaction that 
such sources do not contribute significantly to PM<INF>2.5</INF> 
levels that exceed the standard in the area.
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    Accordingly, if we finalize our proposal to reclassify the SJV as a 
Serious nonattainment area for the 2012 PM<INF>2.5</INF> NAAQS, 
California would be required to submit the emissions inventory required 
under CAA section 172(c)(3), the BACM/BACT provisions required under 
CAA section 189(b)(1)(B), and any NNSR SIP revisions required to 
satisfy the requirements of CAA sections 189(b)(3) and 189(e) for the 
2012 PM<INF>2.5</INF> NAAQS no later than 18 months after the effective 
date of a final reclassification action. Additionally, California would 
be required to submit the Serious area attainment demonstration and all 
attainment-related plan elements no later than the end of the eighth 
calendar year after designation--i.e., by December 31, 2023.
    We note that the 2018 PM<INF>2.5</INF> Plan submitted on May 10, 
2019, includes a Serious area plan containing an attainment 
demonstration, emissions inventory, attainment-related plan elements, 
and BACM/BACT provisions. Also, the State submitted a SIP revision for 
the Serious area NNSR requirements on November 20, 2019. The EPA 
intends to evaluate and act on the Serious area plan and NNSR SIP 
submissions for the 2012 PM<INF>2.5</INF> NAAQS in the SJV through 
separate rulemakings, as appropriate.

VI. Reclassification of Areas of Indian Country

    Eight Indian tribes are located within the boundaries of the SJV 
nonattainment area for the 2012 PM<INF>2.5</INF> NAAQS. These tribes 
include Big Sandy Rancheria of Western Mono Indians of California, Cold 
Springs Rancheria of Mono Indians of California, Northfork Rancheria of 
Mono Indians of California, Picayune Rancheria of Chukchansi Indians of 
California, Santa Rosa Indian Community of the Santa Rosa Rancheria, 
California, Table Mountain Rancheria, Tejon Indian Tribe, and Tule 
River Indian Tribe of the Tule River Reservation, California.
    We have considered the relevance of our proposal to reclassify the 
SJV as Serious nonattainment for the 2012 PM<INF>2.5</INF> standard for 
each tribe located therein. We believe that the same facts and 
circumstances that support the proposal for the non-Indian country 
lands also support the proposal for reservation areas of Indian country 
\259\ and any other areas of Indian country where the EPA or a tribe 
has demonstrated that the tribe has jurisdiction located within the SJV 
nonattainment area. The EPA is therefore proposing to exercise our 
authority under CAA section 188(b)(1) to reclassify areas of Indian 
country geographically located in the SJV nonattainment area. Section 
188(b)(1) broadly authorizes the EPA to reclassify a nonattainment 
area--including any Indian country located within such an area--that 
the EPA determines cannot practicably attain the relevant standard by 
the applicable attainment date.
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    \259\ ``Indian country'' as defined at 18 U.S.C. 1151 refers to 
the following: ``(a) all land within the limits of any Indian 
reservation under the jurisdiction of the United States Government, 
notwithstanding the issuance of any patent, and including rights-of-
way running through the reservation, (b) all dependent Indian 
communities within the borders of the United States whether within 
the original or subsequently acquired territory thereof, and whether 
within or without the limits of a state, and (c) all Indian 
allotments, the Indian titles to which have not been extinguished, 
including rights-of-way running through the same.''

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[[Page 49132]]

    Directly-emitted PM<INF>2.5</INF> and its precursor pollutants 
(i.e., NO<INF>X</INF>, SO<INF>2</INF>, VOC, and ammonia) are emitted 
throughout a nonattainment area and can be transported throughout that 
nonattainment area. Therefore, boundaries for nonattainment areas are 
drawn to encompass both areas with direct sources of the pollutant 
problem as well as nearby areas in the same airshed. Initial 
classifications apply to the entire nonattainment area, i.e., they 
exactly match the nonattainment area boundaries. The EPA believes this 
approach best ensures public health protection from the adverse effects 
of PM<INF>2.5</INF> pollution. Therefore, it is generally 
counterproductive from an air quality and planning perspective to have 
a disparate classification for a land area located within the 
boundaries of a nonattainment area, such as the reservation areas of 
Indian country contained within the SJV PM<INF>2.5</INF> nonattainment 
area. Violations of the 2012 PM<INF>2.5</INF> standard, which are 
measured and modeled throughout the nonattainment area, as well as 
shared meteorological conditions, would dictate the same conclusion. 
Furthermore, emission increases in portions of a PM<INF>2.5</INF> 
nonattainment area that are left classified as Moderate could 
counteract the effects of efforts to attain the standard within the 
overall area because less stringent requirements would apply in those 
Moderate portions relative to those that would apply in the portions of 
the area reclassified to Serious.
    Uniformity of classification throughout a nonattainment area is 
thus a guiding principle and premise when an area is being 
reclassified. In this particular case, we are proposing to determine, 
based on the State's demonstration and current ambient air quality 
trends, that the entire SJV nonattainment area, including all 
reservations areas of Indian country and any other area located within 
the SJV where a tribe has jurisdiction, cannot practicably attain the 
2012 PM<INF>2.5</INF> standard by the applicable Moderate area 
attainment date of December 31, 2021.
    In light of the considerations outlined above that support 
retention of a uniformly-classified PM<INF>2.5</INF> nonattainment 
area, and our proposal to find that it is impracticable for the area to 
attain by the applicable attainment date, we propose to reclassify the 
entire SJV nonattainment area, including reservation areas of Indian 
country and any other area of Indian country located within it where 
the EPA or a tribe has demonstrated that the tribe has jurisdiction, as 
Serious nonattainment for the 2012 PM<INF>2.5</INF> standard.
    Generally, the effect of reclassification is to lower the 
applicable ``major source'' threshold for purposes of the NNSR program 
and the Title V operating permit program from 100 tpy to 70 tpy,\260\ 
thus subjecting additional new or modified stationary sources to these 
requirements. Reclassification also lowers the de minimis threshold 
under the CAA's general conformity requirements from 100 tpy to 70 
tpy.\261\ In this case, however, reclassification would not change the 
``major source'' thresholds because, as a result of the EPA's January 
2016 reclassification of the SJV as a Serious nonattainment area for 
the 2006 PM<INF>2.5</INF> NAAQS, the area is already subject to the 70 
tpy major source threshold for Serious PM<INF>2.5</INF> nonattainment 
areas in CAA section 189(b)(3).\262\ Likewise, reclassification would 
have no impact on the applicable general conformity de minimis 
thresholds, because the SJV is already subject to the 70 tpy de minimis 
threshold for PM<INF>2.5</INF> and all PM<INF>2.5</INF> precursors as a 
result of the EPA's previous reclassification of the area as Serious 
for the 2006 PM<INF>2.5</INF> NAAQS.\263\
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    \260\ CAA sections 189(b)(3) and 501(2)(B).
    \261\ 40 CFR part 93, subpart B.
    \262\ 81 FR 2993.
    \263\ Id. and 40 CFR 93.153(b).
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    The EPA has contacted tribal officials to invite government-to-
government consultation on this rulemaking effort.\264\ The EPA 
specifically solicits additional comment on this proposed rule from 
tribal officials. We note that although eligible tribes may seek EPA 
approval of relevant tribal programs under the CAA, none of the 
affected tribes will be required to submit an implementation plan as a 
result of this reclassification.
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    \264\ We sent letters dated March 3, 2021, to tribal officials 
offering government-to-government consultation. See also a summary 
of the EPA's outreach to tribes in the San Joaquin Valley; 
memorandum dated August 3, 2021, from Rory Mays, Air Planning 
Office, Air and Radiation Division, EPA Region IX, to Docket No. 
EPA-R09-OAR-2021-0543. We did not receive any request for 
consultation.
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VII. Review of Contingency Measure Element for the 2006 
PM<INF>2.5</INF> NAAQS

A. Requirements for Contingency Measures

    With one exception, the SIP requirements for contingency measures 
that apply to areas classified as Serious for the 2006 PM<INF>2.5</INF> 
NAAQS are the same as those described in section IV.H.1 of this 
document for areas that are classified as Moderate for the 2012 
PM<INF>2.5</INF> NAAQS and cannot practicably attain the NAAQS by the 
statutory attainment date, and thus, are not repeated here. However, in 
addition to the contingency measures requirements that apply to 
Moderate areas with adequate impracticability demonstrations, states 
with areas classified as Serious must identify and adopt contingency 
measures to address the potential for the area to fail to attain the 
NAAQS by the applicable attainment date.

B. Summary of State's Contingency Measure Element for 2006 PM2.5 NAAQS

    The EPA deferred action on the contingency measure element of the 
2018 PM<INF>2.5</INF> Plan for the 2006 PM<INF>2.5</INF> NAAQS when we 
took final action on the other elements in the 2018 PM<INF>2.5</INF> 
Plan for that NAAQS.\265\ In this section of this document, we are 
proposing action on the contingency measure element of the 2018 
PM<INF>2.5</INF> Plan for the 2006 PM<INF>2.5</INF> NAAQS.
---------------------------------------------------------------------------

    \265\ 85 FR 44192, at 44193 (July 22, 2020).
---------------------------------------------------------------------------

    The 2018 PM<INF>2.5</INF> Plan addresses the contingency measure 
requirement for the 2006 24-hour PM<INF>2.5</INF> NAAQS by reference to 
the contingency measure portion of a 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 updated 
emissions estimates for the year following the attainment year for use 
in evaluating whether the emissions reductions from the contingency 
measures are sufficient.\266\ Recently, CARB withdrew the enhanced 
enforcement portion of the December 2018 SIP submission as it pertained 
to the 2006 PM<INF>2.5</INF> NAAQS in the SJV.\267\
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    \266\ 2018 PM<INF>2.5</INF> Plan, App. H (revised February 11, 
2020), H-24 to H-26.
    \267\ Letter dated March 19, 2021, from Richard W. Corey, 
Executive Officer, CARB, to Deborah Jordan, Acting Regional 
Administrator, EPA Region IX, with enclosures.
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    Accordingly, we have evaluated the relevant portions of the 2018 
PM<INF>2.5</INF> Plan and District Rule 4901 (specifically, section 
5.7.3 of Rule 4901) for compliance with the applicable requirements for 
Serious areas for the 2006 PM<INF>2.5</INF> NAAQS.
    With respect to the District contingency measure, the 2018 
PM<INF>2.5</INF> Plan calls for the District to amend District Rule 
4901 to include a requirement in the rule with a trigger that that 
would be activated should the EPA issue a final rulemaking that the SJV 
failed to meet a regulatory requirement necessitating

[[Page 49133]]

implementation of a contingency measure. In response to the commitment 
made in the 2018 PM<INF>2.5</INF> Plan, in June 2019, the District 
adopted amendments to Rule 4901 including a contingency measure (in 
section 5.7.3 of the amended rule), and CARB submitted the amended rule 
to the EPA for approval as an attachment to a letter dated July 19, 
2019.\268\ The EPA has taken final action to approve amended Rule 4901, 
but in that 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.\269\ Rather, we approved the 
measure into the SIP because it strengthened the rule by providing a 
possibility of additional curtailment days, and thus potentially 
additional emissions reductions. We indicated that we would evaluate 
whether this provision, in conjunction with other submitted provisions, 
meets the statutory and regulatory requirements for contingency 
measures in future actions. In this proposal, we are now evaluating 
District Rule 4901, specifically, section 5.7.3, for compliance with 
the requirements for contingency measures for purposes of the 2006 
PM<INF>2.5</INF> NAAQS.
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    \268\ Letter dated July 19, 2019, from Richard W. Corey, 
Executive Officer, CARB, to Mike Stoker, Regional Administrator, EPA 
Region IX.
    \269\ 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).
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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 PM<INF>2.5</INF> concentration was 
forecasted to be between 20-65 [micro]g/m\3\ and imposed a level two 
curtailment when the PM<INF>2.5</INF> concentration was forecasted to 
be above 65 [micro]g/m\3\ or the PM<INF>10</INF> concentration was 
forecasted to be above 135 [micro]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 PM<INF>2.5</INF> threshold for these three 
counties from 20 [micro]g/m\3\ to 12 [micro]g/m\3\, and the level two 
PM<INF>2.5</INF> threshold from 65 [micro]g/m\3\ to 35 [micro]g/m\3\. 
The District did not modify the curtailment thresholds for other 
counties in the SJV, and those levels remained at 20 [micro]g/m\3\ for 
level one and 65 [micro]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 
PM<INF>2.5</INF> NAAQS by the applicable attainment date, the 
PM<INF>2.5</INF> 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 PM<INF>2.5</INF> 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 2006 PM<INF>2.5</INF> NAAQS by 
the attainment date, violations of the 2006 PM<INF>2.5</INF> NAAQS were 
only observed at monitors in the hot-spot counties.\270\ Corresponding 
potential emissions reduction in NO<INF>X</INF> would be in the range 
of 0.002 tpd to 0.060 tpd, respectively, but as noted in the preceding 
paragraphs there may be no emissions reduction if the violations are 
monitored in the hot-spot counties only.\271\
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    \270\ See Table B-13 in Appendix B from the District's Final 
Staff Report (June 20, 2019) for revisions to Rule 4901.
    \271\ NO<INF>X</INF> emissions reductions from the contingency 
measure are based on the District's estimates for direct 
PM<INF>2.5</INF> emissions using the ratio of direct 
PM<INF>2.5</INF> to NO<INF>X</INF> in Table 1 of the District's 
Final Staff Report (June 20, 2019) for revisions to Rule 4901.
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    The 2018 PM<INF>2.5</INF> Plan also provides estimates of regional 
emissions in the year following the attainment year with which to 
evaluate the sufficiency of the emissions reductions from the 
contingency measure (i.e., section 5.7.3 of Rule 4901). For the 2006 
PM<INF>2.5</INF> NAAQS, the attainment year is 2024 and the year after 
the attainment year is therefore 2025.\272\ Based on Table H-5 in the 
2018 PM<INF>2.5</INF> Plan, the annual average emission reductions from 
2024 to 2025 due to baseline measures and CARB and the District's 
aggregate tonnage commitment are estimated to be 0 tpd direct 
PM<INF>2.5</INF> and 5.2 tpd NO<INF>X</INF>. For comparison purposes, 
one year's worth of RFP (based on emissions estimates in the 2018 
PM<INF>2.5</INF> Plan) is approximately 0.6 tpd direct PM<INF>2.5</INF> 
and 18.4 tpd NO<INF>X</INF>.\273\
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    \272\ 85 FR 44192, 44192.
    \273\ One year's worth of RFP is based on the difference between 
the emissions estimates for 2013 and 2024 in Table H-6 of Appendix 
H, divided by 11 (i.e., the number of years from 2013 to 2024).
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C. EPA Evaluation and Proposed Action

    For the 2006 PM<INF>2.5</INF> NAAQS, we have similarly evaluated 
the contingency measure demonstration in the 2018 PM<INF>2.5</INF> Plan 
and associated contingency provision of the 2019 amendment to Rule 
4901. Specifically, we have evaluated the contingency provision 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, the latter of which also 
includes submittal of quantitation milestone reports and compliance 
with quantitative milestones.
    As noted in our summary of the State's submission, the contingency 
provision in District Rule 4901 is structured to provide for 
implementation if the area fails to attain the 2006 PM<INF>2.5</INF> 
NAAQS, not before, and is therefore consistent with CAA section 
172(c)(9). However, as structured by the District, the contingency 
provision 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 
said county. In other words, if the EPA's determination of failure to 
attain the NAAQS by the applicable attainment date indicates violations 
at monitoring location sites in Fresno and Kern (``hot spot'' counties) 
and Tulare (non-hot-spot county) counties, the contingency

[[Page 49134]]

provision would provide for emissions reductions by lowering the wood 
burning curtailment thresholds in only Tulare County. 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 provision 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 2006 
PM<INF>2.5</INF> NAAQS by the applicable attainment date.\274\ 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 provision 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.\275\
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    \274\ Section 5.7.3 of Rule 4901 states that ``the District 
shall notify the public of an Episodic Curtailment for the 
PM<INF>2.5</INF> 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 San Joaquin Valley failed to attain the 
applicable PM<INF>2.5</INF> NAAQS.
    \275\ 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'' when 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 the 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 2006 PM<INF>2.5</INF> 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 
provision of District Rule 4901 provides for such reductions only under 
certain circumstances and should be revised to provide for additional 
emissions reductions in the SJV (if triggered) regardless of which 
monitoring site(s) is determined to be violating the 2006 
PM<INF>2.5</INF> NAAQS as of the attainment date.\276\
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    \276\ 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 2006 PM<INF>2.5</INF> NAAQS by the applicable 
attainment date.
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    Next, we considered the adequacy of the section 5.7.3 of District 
Rule 4901 from the standpoint of the magnitude of emissions reductions 
the measures would provide (if triggered). Neither the CAA nor the 
EPA's implementing regulations for the PM<INF>2.5</INF> NAAQS establish 
a specific amount of emissions reductions that implementation of 
contingency measures must achieve, but we generally expect that 
contingency measures should provide for emissions reductions 
approximately equivalent to one year's worth of RFP, which amounts to 
reductions of approximately 0.6 tpd of direct PM<INF>2.5</INF> and 18.4 
tpd of NO<INF>X</INF> for the 2006 PM<INF>2.5</INF> NAAQS in the 
SJV.\277\ As noted in our summary of the State's submission, the 
emissions reductions from the contingency provisions in District Rule 
4901 would amount to approximately 0.00 tpd to 0.387 tpd of direct 
PM<INF>2.5</INF>, which equates to approximately 0% to 67% of one 
year's worth of RFP for direct PM<INF>2.5</INF>. With respect to 
NO<INF>X</INF> emissions reductions, the contingency provisions 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 NO<INF>X</INF>.
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    \277\ 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 PM<INF>2.5</INF> Plan by 11, i.e., 
the number of years between 2013 and 2024. As part of the EPA's 
final approval of the State's attainment plan for the 2006 
PM<INF>2.5</INF> NAAQS, we concluded that ammonia, SO<INF>X</INF>, 
and VOC emissions do not contribute significantly to ambient 
PM<INF>2.5</INF> levels that exceed the 2006 PM<INF>2.5</INF> NAAQS 
in the San Joaquin Valley. 85 FR 17382, at 17390-17396 (March 27, 
2020) (proposed rule); finalized at 85 FR 44192 (July 22, 2020).
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    The State's contingency measure element in the 2018 
PM<INF>2.5</INF> Plan provides the larger SIP planning context in which 
to judge the adequacy of the amount of emission reductions resulting 
from the contingency measure by calculating the surplus emissions 
reductions estimated to be achieved in the year after the attainment 
year. More specifically, the 2018 PM<INF>2.5</INF> Plan identifies 
additional NO<INF>X</INF> reductions in the year following the 
attainment year of 2024. For the SJV, the estimates of additional 
reductions in the post-attainment year (2025) are 0 tpd direct 
PM<INF>2.5</INF> and 5.2 tpd NO<INF>X</INF>.\278\ Generally, we will 
consider such surplus emissions reductions in evaluating the 
sufficiency of the emissions reductions from contingency measures 
identified by the state, however, in this case, because the identified 
contingency measure may result in no emissions reductions, the larger 
planning context is not relevant to our review of the sufficiency of 
the contingency measure.
---------------------------------------------------------------------------

    \278\ These estimates are based on the annual average emission 
reductions from 2024 to 2025 due to baseline measures and CARB and 
the District's aggregate tonnage commitment in Table H-5 of Appendix 
H (updated February 11, 2020) of the 2018 PM<INF>2.5</INF> Plan. We 
also note that Table H-13 of Appendix H indicates that the year-
over-year reductions for purposes of the 2006 PM<INF>2.5</INF> NAAQS 
is 0.1 tpd direct PM<INF>2.5</INF> and 4.2 tpd NO<INF>X</INF>. 
However, the estimates in Table H-13 reflect emissions changes 
associated only with mobile sources whereas the appropriate 
comparison includes the entire emissions inventory.
---------------------------------------------------------------------------

    For these reasons, we propose to disapprove the contingency measure 
element of the 2018 PM<INF>2.5</INF> Plan under CAA section 179(c)(9) 
and 40 CFR 51.1014 with respect to the State's Serious area attainment 
plan for the 2006 PM<INF>2.5</INF> 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, as the contingency measure element and the contingency 
provision of Rule 4901 lack any to-be-triggered measure for failure to 
meet a quantitative milestone, submit a quantitative milestone report, 
or failure to meet an RFP requirement, we propose that the submission 
is also inadequate for RFP contingency measures.
    Lastly, if the EPA finalizes the proposed disapproval of the 
contingency measure element for the 2006 PM<INF>2.5</INF> NAAQS, the 
area would be eligible for a protective finding under the 
transportation conformity rule because the 2018 PM<INF>2.5</INF> Plan 
reflects adopted control measures and contains enforceable commitments 
that fully satisfy the emissions reductions requirements for RFP and 
attainment for the 2006 PM<INF>2.5</INF> NAAQS.\279\
---------------------------------------------------------------------------

    \279\ 40 CFR 93.120(a)(3).

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[[Page 49135]]

VIII. Summary of Proposed Actions and Request for Public Comment

    Under CAA section 110(k)(3), the EPA is proposing to approve the 
following elements of the 2016 PM<INF>2.5</INF> Plan and 2018 
PM<INF>2.5</INF> Plan submitted by California to address the CAA's 
Moderate area planning requirements for the 2012 PM<INF>2.5</INF> NAAQS 
in the SJV nonattainment area:

    1. The 2013 base year emissions inventories in the 2016 
PM<INF>2.5</INF> Plan, as revised in the 2018 PM<INF>2.5</INF> Plan, 
as meeting the requirements of CAA section 172(c)(3) and 40 CFR 
51.1008(a);
    2. The reasonably available control measures/reasonably 
available control technology demonstration in the 2016 
PM<INF>2.5</INF> Plan, as supplemented in the 2018 PM<INF>2.5</INF> 
Plan, as meeting the requirements of CAA sections 172(c)(1) and 
189(a)(1)(C);
    3. The demonstration in the 2016 PM<INF>2.5</INF> Plan that 
attainment by the Moderate area attainment date of December 31, 
2021, is impracticable as meeting the requirements of CAA section 
189(a)(1)(B)(ii) and 40 CFR 51.1011(a);
    4. The reasonable further progress demonstration in the 2016 
PM<INF>2.5</INF> Plan, as revised in 2018 PM<INF>2.5</INF> Plan, as 
meeting the requirements of CAA section 172(c)(2) and 40 CFR 
51.1012(a);
    5. The quantitative milestones in the 2016 PM<INF>2.5</INF> 
Plan, as revised in the 2018 PM<INF>2.5</INF> Plan and the Valley 
State SIP Strategy, as meeting the requirements of CAA section 
189(c) and 40 CFR 51.1013(a)(1); and
    6. The motor vehicle emissions budgets for 2022 in the 2018 
PM<INF>2.5</INF> Plan as shown in Table 6 of this proposed rule 
because they are derived from an approvable RFP demonstration and 
meet the requirements of CAA section 176(c) and 40 CFR part 93, 
subpart A. With respect to the budgets, we are proposing to limit 
the duration of the approval of the budgets to last only until the 
effective date of the EPA's adequacy finding for any subsequently 
submitted budgets. We are proposing to do so at CARB's request and 
in light of the benefits of using EMFAC2017-derived budgets prior to 
our taking final action on the future SIP revision that includes the 
updated budgets.

    Pursuant to CAA section 110(k)(3), the EPA proposes to disapprove 
the contingency measure element of the 2016 PM<INF>2.5</INF> Plan for 
the 2012 PM<INF>2.5</INF> NAAQS, as revised in the 2018 
PM<INF>2.5</INF> Plan and supplemented by section 5.7.3 of District 
Rule 4901, and the contingency measure element of the 2018 
PM<INF>2.5</INF> Plan for the 2006 PM<INF>2.5</INF> NAAQS, as 
supplemented by section 5.7.3 of District Rule 4901, because, among 
other reasons, the elements include 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, with respect to the contingency measure element 
in the 2018 PM<INF>2.5</INF> Plan for the 2006 PM<INF>2.5</INF> NAAQS 
(as supplemented by section 5.7.3 of District Rule 4901), the element 
includes a specific measure that may not result in any emissions 
reductions following a failure to attain the 2006 PM<INF>2.5</INF> 
NAAQS by the applicable attainment date under certain circumstances.
    If we finalize the disapproval of the contingency measure elements 
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.\280\ 
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.
---------------------------------------------------------------------------

    \280\ 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 the plan two years after the effective date 
of disapproval unless the State submits, and the EPA approves, the 
required SIP submittal. As a result of the EPA's December 6, 2018 
determination that California had failed to submit the required 
contingency measures for the 2006 PM<INF>2.5</INF> NAAQS and the 2012 
PM<INF>2.5</INF> NAAQS, among other required SIP submissions for the 
SJV,\281\ the EPA is already subject to a statutory deadline to 
promulgate a FIP for this purpose no later than two years after the 
effective date of that determination.\282\
---------------------------------------------------------------------------

    \281\ 83 FR 62720.
    \282\ Id.
---------------------------------------------------------------------------

    Also, because we previously approved the Serious area plan RFP and 
attainment demonstrations and the motor vehicle emissions budgets for 
the 2006 PM<INF>2.5</INF> NAAQS,\283\ and because in this proposed rule 
we are proposing to approve the Moderate area plan RACM, additional 
reasonable measures, and RFP demonstrations, and motor vehicle emission 
budgets for the 2012 PM<INF>2.5</INF> NAAQS, we are proposing to issue 
a protective finding under 40 CFR 93.120(a)(3) to the disapproval of 
the contingency measures elements. 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 Plan (RTP) and Transportation Improvement 
Programs (TIP) 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.\284\ 
Under a protective finding, the final disapproval of the contingency 
measures elements would not result in a transportation conformity 
freeze in the SJV PM<INF>2.5</INF> nonattainment area and the MPOs may 
continue to make transportation conformity determinations.
---------------------------------------------------------------------------

    \283\ 85 FR 44192.
    \284\ 40 CFR 93.120(a)(2).
---------------------------------------------------------------------------

    Finally, pursuant to CAA section 188(b)(1), the EPA is proposing to 
reclassify the SJV PM<INF>2.5</INF> nonattainment area, including 
reservation areas of Indian country and any other area where the EPA or 
a tribe has demonstrated that a tribe has jurisdiction within the SJV, 
as Serious nonattainment for the 2012 PM<INF>2.5</INF> standard based 
on the agency's determination that the SJV cannot practicably attain 
the standard by the Moderate area attainment date of December 31, 2021. 
Upon final reclassification as a Serious area, California will be 
required to submit, within 18 months after the effective date of the 
reclassification, an emissions inventory, provisions to assure that 
BACM shall be implemented no later than four years after the date of 
reclassification, and any NNSR SIP revisions required to satisfy the 
requirements of CAA sections 189(b)(3) and 189(e). California will also 
be required to submit, by December 31, 2023, a Serious area plan that 
satisfies the requirements of part D of title I of the Act. This plan 
must include a demonstration that the SJV will attain the 2012 
PM<INF>2.5</INF> standard 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).
    We note that the 2018 PM<INF>2.5</INF> Plan, submitted concurrently 
with the 2016 PM<INF>2.5</INF> Plan on May 10, 2019, includes a Serious 
area attainment demonstration, emissions inventory, attainment-related 
plan elements, and BACM/BACT provisions. The State also submitted a SIP 
submission for the Serious area NNSR requirements on November 20,

[[Page 49136]]

2019. The EPA intends to evaluate and act on the Serious area plan and 
NNSR SIP submissions for the 2012 PM<INF>2.5</INF> NAAQS in the SJV 
through separate rulemakings, as appropriate.\285\
---------------------------------------------------------------------------

    \285\ We are establishing deadlines for submittal of SIP 
revisions that have already been submitted to timely address any 
elements that may be withdrawn in the future.
---------------------------------------------------------------------------

    In addition, because the EPA is proposing to similarly reclassify 
reservation areas of Indian country and any other area of Indian 
country where the EPA or a tribe has demonstrated that the tribe has 
jurisdiction within the SJV PM<INF>2.5</INF> nonattainment area as 
Serious nonattainment for the 2012 PM<INF>2.5</INF> standard, 
consistent with our proposed reclassification of the surrounding non-
Indian country lands, the EPA has invited consultation with interested 
tribes concerning this issue. Although eligible tribes may seek the 
EPA's approval of relevant tribal programs under the CAA, none of the 
affected tribes will be required to submit an implementation plan as a 
result of this reclassification.
    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.

IX. Statutory and Executive Order Reviews

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

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

    The proposed actions are not a significant regulatory action and 
were therefore not submitted to the Office of Management and Budget 
(OMB) for review.

B. Paperwork Reduction Act (PRA)

    The proposed actions do not impose an information collection burden 
under the PRA because they do not contain any information collection 
activities.

C. Regulatory Flexibility Act (RFA)

    I certify that the proposed actions will not have a significant 
economic impact on a substantial number of small entities under the 
RFA. The proposed actions will not impose any requirements on small 
entities. This proposed rule would approve or disapprove State plans as 
meeting federal requirements and would not impose additional 
requirements beyond those imposed by State law. Additionally, the 
proposed rule would reclassify the SJV nonattainment area as Serious 
nonattainment for the 2012 PM<INF>2.5</INF> NAAQS and would not itself 
regulate small entities.

D. Unfunded Mandates Reform Act (UMRA)

    The proposed actions do not contain an unfunded mandate of $100 
million or more as described in UMRA, and does not significantly or 
uniquely affect small governments. This proposed rule would approve or 
disapprove State plans as meeting federal requirements and would not 
impose additional requirements beyond those imposed by State law. 
Additionally, the proposed rule would reclassify the SJV nonattainment 
area as Serious nonattainment for the 2012 PM<INF>2.5</INF> NAAQS and 
would not itself impose any federal intergovernmental mandate. The 
proposed actions would not require any tribe to submit implementation 
plans.

E. Executive Order 13132: Federalism

    The proposed actions do not have federalism implications. They 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

    Executive Order 13175, entitled ``Consultation and Coordination 
with Indian Tribal Governments'' (65 FR 67249, November 9, 2000), 
requires the EPA to develop an accountable process to ensure 
``meaningful and timely input by tribal officials in the development of 
regulatory policies that have tribal implications.'' ``Policies that 
have Tribal implications'' is defined in the Executive Order to include 
regulations that have ``substantial direct effects on one or more 
Indian tribes, on the relationship between the Federal government and 
the Indian tribes, or on the distribution of power and responsibilities 
between the Federal government and Indian Tribes.''
    Eight Indian tribes are located within the boundaries of the SJV 
nonattainment area for the 2012 PM<INF>2.5</INF> NAAQS: The Big Sandy 
Rancheria of Western Mono Indians of California, the Cold Springs 
Rancheria of Mono Indians of California, the Northfork Rancheria of 
Mono Indians of California, the Picayune Rancheria of Chukchansi 
Indians of California, the Santa Rosa Indian Community of the Santa 
Rosa Rancheria, California, the Table Mountain Rancheria, the Tejon 
Indian Tribe, and the Tule River Indian Tribe of the Tule River 
Reservation, California.
    The EPA's proposed actions on the SIP elements submitted by 
California to address the Moderate area requirements for the 2012 
PM<INF>2.5</INF> NAAQS and the contingency measure requirement for the 
2006 PM<INF>2.5</INF> NAAQS would not have tribal implications 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. In those areas of Indian country, the proposed 
actions on the SIP submittals do not have tribal implications and will 
not impose substantial direct costs on tribal governments or preempt 
tribal law as specified by Executive Order 13175.
    The EPA has concluded that the proposed reclassification might have 
tribal implications for the purposes of Executive Order 13175, but 
would not impose substantial direct costs upon the tribes, nor would it 
preempt tribal law. The proposed reclassification from Moderate to 
Serious for a PM<INF>2.5</INF> NAAQS would typically affect the EPA's 
implementation of the new source review program because of the lower 
``major source'' threshold triggered by reclassification (70 tons per 
year for direct PM<INF>2.5</INF> and precursors to PM<INF>2.5</INF>). 
However, because the SJV nonattainment area is already classified as 
Serious for the 1997 and 2006 PM<INF>2.5</INF> NAAQS, the lower 
thresholds already apply within the nonattainment area, and the 
proposed reclassification from Moderate to Serious for the 2012 
PM<INF>2.5</INF> NAAQS would have no additional effect. The same is 
true for any tribal projects that require federal permits, approvals, 
or funding. Such projects are subject to the requirements of the EPA's 
general conformity rule, and federal permits, approvals, or funding for 
the projects would typically become more difficult to obtain because of 
the lower de minimis thresholds triggered by reclassification but, in 
this case, the lower de minimis thresholds already apply within the 
SJV.
    Given the potential implications, the EPA contacted tribal 
officials during the process of developing this proposed rule to 
provide an opportunity to have meaningful and timely input into its 
development. On March 3, 2021, we sent letters to leaders of the eight 
tribes with areas of Indian country in the SJV nonattainment area 
inviting government-to-government consultation on the rulemaking 
effort. We requested that the tribal leaders, or their

[[Page 49137]]

designated consultation representatives, notify us of their interest in 
government-to-government consultation by April 5, 2021. We intend to 
continue communicating with all eight tribes located within the 
boundaries of the SJV nonattainment area for the 2012 PM<INF>2.5</INF> 
NAAQS as we move forward in developing a final rule. The EPA 
specifically solicits additional comment on this proposed rule from 
tribal officials.

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. The proposed rule is not subject 
to Executive Order 13045 because it would approve or disapprove a State 
plan implementing a federal standard, and reclassify the SJV 
nonattainment area as Serious nonattainment for the 2012 
PM<INF>2.5</INF> NAAQS, triggering Serious area planning requirements 
under the CAA. This proposed action does not establish an environmental 
standard intended to mitigate health or safety risks.

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

    This proposed rule 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

    This rulemaking does not involve technical standards.

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

    The EPA has determined that the proposed actions will not have 
potential disproportionately high and adverse human health or 
environmental effects on minority or low-income populations because 
they do not affect the level of protection provided to human health or 
the environment. The proposed actions would only approve or disapprove 
State plans implementing a federal standard, and reclassify the SJV 
nonattainment area as Serious nonattainment for the 2012 
PM<INF>2.5</INF> NAAQS, triggering additional Serious area planning 
requirements under the CAA.

List of Subjects

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.

40 CFR Part 81

    Environmental protection, Air pollution control, Particulate 
matter.

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

    Dated: August 25, 2021.
Elizabeth Adams,
Acting Regional Administrator, Region IX.
[FR Doc. 2021-18764 Filed 8-31-21; 8:45 am]
BILLING CODE 6560-50-P


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