PM2.5 and NOX in the SJV, identification of
potential control measures for such sources, assessment of the
stringency and feasibility of the potential control measures, and
adoption and implementation of feasible control measures.\128\ CARB
further discusses its current mobile source control program and
additional mobile source measures in the Valley State SIP Strategy.
Appendix D of the 2018 PM2.5 Plan also describes the current
efforts of the eight local jurisdiction metropolitan planning
organizations (MPOs) to implement cost-effective transportation control
measures (TCMs) in the SJV.\129\ Based on these analyses, CARB
concludes that all best available control measures for mobile sources
are in place in the SJV for NOX and directly emitted
PM2.5 for purposes of meeting the BACM/BACT requirement for
the 2012 annual PM2.5 NAAQS.
---------------------------------------------------------------------------

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

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

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

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

    We provide an evaluation of many of the District's control measures
for stationary sources and area sources in section III of the EPA's
``Technical Support Document, EPA Evaluation, San Joaquin Valley
Serious Area Plan for the 2012 Annual PM2.5 NAAQS,''
December 2021 (``EPA's 2012 Annual PM2.5 TSD'').
    Mobile source categories for which CARB has primary responsibility
for reducing emissions in California include most new and existing on-
and non-road engines and vehicles and motor vehicle fuels. The SJV
PM2.5 Plan's BACM demonstration provides a general
description of CARB's key mobile source programs and regulations and a
comprehensive table listing on-road and non-road mobile source
regulatory actions taken by CARB since 1985.\131\
---------------------------------------------------------------------------

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

    Appendix D of the 2018 PM2.5 Plan describes the current
efforts of the eight local jurisdiction MPOs to implement cost-
effective TCMs in the SJV.\132\ TCMs are projects that reduce air
pollutants from transportation sources by reducing vehicle use, traffic
congestion, or vehicle miles traveled. The eight MPOs in the SJV
currently implement TCMs as part of the Congestion Mitigation and Air
Quality cost effectiveness policy adopted by the eight local
jurisdiction MPOs and in the development of each Regional
Transportation Plan (RTP). The Congestion Mitigation and Air Quality
policy, which is included in a number of the District's prior
attainment plan submissions for the ozone and PM2.5 NAAQS,
provides a standardized process for distributing 20% of the Congestion
Mitigation and Air Quality funds to projects that meet a minimum cost
effectiveness threshold beginning in fiscal year 2011. The MPOs
revisited the minimum cost effectiveness standard during the
development of their 2018 RTPs and 2019 Federal Transportation
Improvement Program and concluded that they were implementing all
reasonable transportation control measures.\133\ Appendix D of the
District's ``2016 Ozone Plan for 2008 8-Hour Ozone Standard,'' adopted
June 16, 2016, contains a listing of adopted TCMs for the SJV.\134\
---------------------------------------------------------------------------

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

    We have reviewed the State's and District's analysis and
determination in the SJV PM2.5 Plan that their baseline
mobile, stationary, and area source control measures meet the
requirements for BACM for sources of direct PM2.5 and
applicable PM2.5 plan precursors (i.e., NOX) for
purposes of the 2012 annual PM2.5 NAAQS. In our review, we
considered our evaluation of the State's and District's rules in
connection with our approval of the demonstrations for BACM (including
BACT) and MSM for the 2006 24-hour PM2.5 NAAQS.\135\ We
conclude that the evaluation processes followed by CARB and the
District in the SJV PM2.5 Plan to identify potential BACM
were generally consistent with the requirements of the PM2.5
SIP Requirements Rule, the State's and District's evaluation of
potential measures is appropriate, and the State and District have
provided reasoned justifications for their rejection of potential
measures based on technological or economic infeasibility. We also
agree with the District's conclusion that the eight MPOs are
implementing all reasonable TCMs in the SJV and propose to find that
these TCMs implement BACM for transportation sources.
---------------------------------------------------------------------------

    \135\ 85 FR 44192. The EPA provides a more detailed evaluation
of many of the District's control measures for stationary and area
sources in two supporting documents: The EPA's ``Technical Support
Document, EPA Evaluation of BACM/MSM, San Joaquin Valley
PM2.5 Plan for the 2006 PM2.5 NAAQS,''
February 2020; and the EPA's ``Response to Comments Document for the
EPA's Final Action on the San Joaquin Valley Serious Area Plan for
the 2006 PM2.5 NAAQS,'' June 2020.
---------------------------------------------------------------------------

    For the foregoing reasons, we propose to find that the SJV
PM2.5 Plan provides for the implementation of BACM for
sources of direct PM2.5 and NOX as expeditiously
as practicable in accordance with the requirements of CAA section
189(b)(1)(B), and in satisfaction of the Serious area plan requirements
for the 2012 annual PM2.5 NAAQS.

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

    Section 189(e) of the CAA specifically requires that the control
requirements applicable to major stationary sources of direct
PM2.5 also apply to major stationary sources of
PM2.5 precursors, except where the Administrator determines
that such sources do not contribute significantly to PM2.5
levels that exceed the standards in the area.\136\ The control
requirements applicable to major stationary sources of direct
PM2.5 in a Serious PM2.5 nonattainment area
include, at minimum, the requirements of a nonattainment NSR permit
program meeting the requirements of CAA sections 172(c)(5) and
189(b)(3). The publication of our final action to reclassify the SJV
area as Serious nonattainment for the 2012 annual PM2.5
NAAQS established a deadline of June 27, 2023, for the State to submit
nonattainment NSR SIP revisions addressing the requirements of CAA
sections 189(b)(3) and 189(e) of the Act for the 2012 annual
PM2.5 NAAQS.\137\
---------------------------------------------------------------------------

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

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

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

F. Attainment Demonstration

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

strategy provides for attainment of the PM2.5 NAAQS as
expeditiously as practicable.\139\ For purposes of determining the
attainment date that is as expeditious as practicable, the state must
conduct future year modeling that takes into account emissions growth,
known controls (including any controls determined to be RACM, RACT, and
additional reasonable measures, and BACM, BACT, and additional feasible
measures), and any other emissions controls that are needed for
expeditious attainment of the NAAQS.\140\ The regulatory requirements
for Serious area plans are codified at 40 CFR 51.1010 (control strategy
requirements) and 40 CFR 51.1011(b) (attainment demonstration and
modeling requirements).
---------------------------------------------------------------------------

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

    CARB and the District's aggregate tonnage commitments sum to 33.88
tpd NOX and 2.2 tpd direct PM2.5 emission
reductions. We provide further detail on CARB and the District's
aggregate tonnage commitments in sections IV.F.3.b and IV.F.3.d of this
proposed rule and in section IV.B of the EPA's 2012 Annual
PM2.5 TSD.
    We note that the SJV PM2.5 Plan generally relies on
annual average emission inventory and control strategy estimates,
consistent with the annual average form of the 2012 annual
PM2.5 NAAQS. Table 4 provides a summary of the 2013 base
year emissions and the reductions from baseline measures, additional
State measures, and additional District measures that the Plan projects
will result in attainment of the 2012 annual PM2.5 NAAQS in
the SJV by December 31, 2025.\150\
---------------------------------------------------------------------------

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

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

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

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

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

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

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

    In the 2018 PM2.5 Plan, the State explains that mobile
sources emit over 85% of the NOX in the SJV and that CARB
has adopted and amended regulations to reduce public exposure to diesel
particulate matter, which includes direct PM2.5, and
NOX, from ``fuel sources, freight transport sources like
heavy-duty diesel trucks, transportation sources like passenger cars
and buses, and non-road sources like large construction equipment.''
\153\
---------------------------------------------------------------------------

    \153\ 2018 PM2.5 Plan, Ch. 4, 4-9 and Valley State
SIP Strategy, 4. For CARB's analysis of its mobile source measures
for BACM and MSM, see 2018 PM2.5 Plan, App. D, including
analyses for on-road light-duty vehicles and fuels (starting page D-
17), on-road heavy-duty vehicles and fuels (starting page D-35), and
non-road sources (starting page D-64).
---------------------------------------------------------------------------

    Given the need for substantial emissions reductions from mobile and
area sources to meet the NAAQS in California nonattainment areas, the
State of California has developed stringent control measures for on-
road and non-road mobile sources and the fuels that power them.
California has unique authority under CAA section 209 (subject to a
waiver by the EPA) to adopt and implement new emissions standards for
many categories of on-road vehicles and engines and new and in-use non-
road vehicles and engines. The EPA has approved multiple mobile source
regulations for which waivers or authorizations have been issued as
revisions to the California SIP.\154\
---------------------------------------------------------------------------

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

    CARB's mobile source program extends beyond regulations that are
subject to the waiver or authorization process set forth in CAA section
209 to include standards and other requirements to control emissions
from in-use heavy-duty trucks and buses, gasoline and diesel fuel
specifications, and many other types of mobile sources. Generally,
these regulations have also been submitted and approved as revisions to
the California SIP.\155\
---------------------------------------------------------------------------

    \155\ See, e.g., the EPA's approval of standards and other
requirements to control emissions from in-use heavy-duty diesel
trucks, 77 FR 20308 (April 4, 2012), and revisions to the California
on-road reformulated gasoline and diesel fuel regulations, 75 FR
26653 (May 12, 2010).
---------------------------------------------------------------------------

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

    \156\ 2018 PM2.5 Plan, Ch. 4, 4-3. For the District's
analysis of its stationary source measures for BACM and MSM, see
2018 PM2.5 Plan, App. C.
    \157\ Id. at Ch. 4, Table 4-1.
    \158\ See EPA Region IX's website for information on District
control measures that have been approved into the California SIP,
available at: https://www.epa.gov/sips-ca/epa-approved-san-joaquin-valley-unified-air-district-regulations-california-sip.
---------------------------------------------------------------------------

    First, the District amended Rule 4905 (``Natural Gas-fired, Fan-
type, Residential Central Furnaces'') on June 21, 2018, to extend the
period during which manufacturers may pay emission fees in lieu of
meeting the rule's NOX emission limits.\159\ CARB submitted
the amended rule to the EPA on November 21, 2018. However, the District
amended Rule 4905 once more on October 15, 2020, to further extend the
period during which manufacturers of weatherized furnaces may pay
emission fees in lieu of meeting the rule's NOX emission
limits.\160\ CARB submitted the rule as amended October 15, 2020, to
the EPA on December 30, 2020, and simultaneously withdrew the rule as
amended June 21, 2018.\161\ The EPA has not yet proposed any action on
this submission.
---------------------------------------------------------------------------

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

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

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

    \162\ 81 FR 17390 (March 29, 2016) (approving Rule 4905 as
amended January 22, 2015).
    \163\ EPA Region IX, ``Technical Support Document for EPA's
Proposed Rulemaking for the California State Implementation Plan
(SIP), San Joaquin Valley Unified Air Pollution Control District's
Rule 4905, Natural Gas-Fired, Fan-Type Central Furnaces,'' October
5, 2015, n. 8.
    \164\ 2018 PM2.5 Plan, App. C, C-290.
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    Second, the 2018 PM2.5 Plan lists Rule 4203
(``Particulate Matter Emissions from Incineration of Combustible
Refuse'') as a baseline measure. This rule has not been approved into
the California SIP.\165\ Appendix C of the 2018 PM2.5 Plan
indicates, however, that the emissions inventory for incineration of
combustible refuse is 0.00 tpd of NOX and 0.00 tpd direct
PM2.5 from 2013 through 2025.\166\ Thus, although the
District included this rule as a baseline measure, there are no
meaningful reductions associated with this rule that would affect the
attainment demonstration in the SJV PM2.5 Plan.
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    \165\ The EPA does not have any pending SIP submission for Rule
4203.
    \166\ 2018 PM2.5 Plan, App. C, C-46.
---------------------------------------------------------------------------

    In sum, although Table 4-1 of the 2018 PM2.5 Plan
identifies two baseline measures that are not creditable for SIP
purposes at this time, we conclude that the total emission reductions
attributed to these two measures in the future baseline inventories
would not materially affect the attainment demonstration in the Plan.
(b) Additional Measures and Aggregate Commitments
    The SJV PM2.5 Plan identifies a series of additional
CARB and District commitments to achieve emission reductions through
additional control measures beyond baseline measures that will
contribute to expeditious attainment of the 2012 annual
PM2.5 NAAQS. As discussed in section IV.F.2 of this proposed
rule, for mobile sources, CARB's commitment identifies a list of 12
State regulatory measures and 3 incentive-based measures that CARB has
committed to propose to its Board for consideration by specific
years.\167\ For stationary sources, the District's commitment
identifies a list of nine regulatory measures and three incentive-based
measures that the District has committed to propose to its Board for
consideration by specific years.\168\ The Plan contains CARB and the
District's estimates of the emission reductions that would be achieved
by each of these additional measures, if adopted.\169\
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    \167\ CARB Resolution 18-49, Attachment A and Valley State SIP
Strategy, Table 7 (``State Measures and Schedule for the San Joaquin
Valley'').
    \168\ SJVUAPCD Governing Board Resolution 18-11-16 and 2018
PM2.5 Plan, Table 4-4 (``Proposed Regulatory Measures'')
and Table 4-5 (``Proposed Incentive-Based Measures'').
    \169\ 2018 PM2.5 Plan, Ch. 4, Table 4-3 (''Emission
Reductions from District Measures'') and Table 4-9 (''San Joaquin
Valley Expected Emission Reductions from State Measures'') and
Valley State SIP Strategy, Table 8 (``San Joaquin Valley Expected
Emission Reductions from State Measures'').
---------------------------------------------------------------------------

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

documentation in development for forthcoming regulations.\178\
---------------------------------------------------------------------------

    \177\ ``Progress Report and Technical Submittal for the 2012
PM2.5 Standard San Joaquin Valley,'' October 19, 2021.
Transmitted to the EPA by letter dated October 20, 2021, from
Richard W. Corey, Executive Officer, CARB, to Deborah Jordan, Acting
Regional Administrator, EPA Region IX. See sections of 2021 Progress
Report entitled ``Progress in Implementing District Measures'' and
``Progress in Implementing CARB Measures.''
    \178\ 2021 Progress Report, tables 2 and 3.
---------------------------------------------------------------------------

    Together, as of December 2021, CARB and the District together have
adopted 18 measures of the 27 control measure commitments in the SJV
PM2.5 Plan and have begun the public process on 5 of the
remaining control measure commitments. For CARB's portion, CARB has
adopted 10 of the 15 measures in its commitment (including one
incentive-based measure) and begun the public process on 3 of its
remaining 5 measures. The adopted measures include, for example, the
Heavy-Duty Vehicle Inspection and Maintenance Program (``Heavy-Duty I/
M''), the California Heavy-Duty Low-NOX Engine Standard, the
Small Off-Road Engines (SORE) regulation, and the Accelerated Turnover
of Agricultural Equipment Incentive Projects (``Agricultural Equipment
Incentive Measure''). For the District's portion of the control measure
commitments, the District has adopted 8 of the 12 measures in its
commitment (including one incentive-based measure) and begun the public
process on two of the remaining four measures. The adopted measures
include, for example, amendments to Rule 4311 (``Flares''), Rule 4702
(``Internal Combustion Engines''), and Rule 4901 (``Woodburning
Fireplaces and Wood Burning Heaters'') (Hot-spot strategy), and the
Residential Wood Burning Devices Incentive Projects measure.
    Accordingly, the EPA considers that, although CARB and the District
have not met the commitment deadlines for several measures, as
discussed further in this proposed rule, they have nonetheless made
substantial progress in developing and adopting the regulatory measures
listed in their respective control measure commitments. We provide
further detail on CARB and the District's control measure commitments
in section IV.A of the EPA's 2012 Annual PM2.5 TSD
(including tables IV-A and IV-B regarding CARB and the District's
control measure commitments, respectively).
    Regarding the remaining nine measures not yet proposed for board
consideration, we note that one measure, Rule 4550 (``Conservation
Management Practices''), has an action year of 2022 in the 2018
PM2.5 Plan (i.e., it is not yet due for board consideration)
and that four regulatory measures and four incentive-based measures are
overdue.
    The four overdue regulatory measures are: The Zero-Emission Airport
Ground Support Equipment measure; the Zero-Emission Off-Road Forklift
Regulation Phase 1 measure; the Low-emission Diesel Fuel Requirement;
and Rule 4692 (``Commercial Under-fired Charbroiling (Hot-spot
Strategy)''). While they have not proposed these measures to their
respective boards, CARB and the District timely began the public
process on each of the four measures. CARB anticipates board
consideration of the diesel fuel measures in 2022 and the forklift
measure as early as 2022 and continues to develop the airport ground
support equipment measure. The District adopted the ``Commercial
Underfired Charbroiling Emission Reduction Strategy'' on December 17,
2020, and continues to evaluate potential amendments to Rule 4692 in
the near future.\179\
---------------------------------------------------------------------------

    \179\ Id. at 8-9, 20-22, and tables 2 and 3.
---------------------------------------------------------------------------

    The four overdue incentive-based control measures are for the
Accelerated Turnover of Trucks and Buses Incentive Projects, the
Accelerated Turnover of Off-road Equipment Incentive Projects, the
Agricultural Operation Internal Combustion Engines Incentive Projects,
and the Commercial Under-fired Charbroiling Incentive Projects. CARB
and the District continue to invest in reducing emissions from these
sources, as well as other incentive programs not named among the 27
control measure commitments, such as those for nut harvesting and
landscape maintenance equipment.\180\ However, while CARB and the
District have discussed the proposed programs at certain board
hearings,\181\ the EPA is not aware that CARB or the District have
started public process for the four incentive-based control measure
commitments as enforceable measures to be submitted for inclusion as
control measures in the California SIP.
---------------------------------------------------------------------------

    \180\ CARB, ``Long-Term Heavy-Duty Investment Strategy,
Including Fiscal Year 2020-21 Three-Year Recommendations for Low
Carbon Transportation Investments,'' (App. D to CARB's ``Proposed
Fiscal Year 2021-22 Funding Plan for Clean Transportation
Incentives''), release date October 8, 2021; and SJVUAPCD,
``Comprehensive Annual Financial Report, Fiscal Year Ended June 30,
2020,'' release date December 23, 2020. See also, 2021 Progress
Report, 3 and 15.
    \181\ For example, CARB staff discussed the Accelerated Turnover
of Trucks and Buses Incentive Measure at its annual 2020 update to
the CARB Board. CARB presentation, ``Update on the 2018
PM2.5 SIP for the San Joaquin Valley,'' October 22, 2020.
District staff discussed and adopted an emission reductions strategy
for commercial under-fired charbroiling, including incentives, in
December 2020. SJVUAPCD, ``Item Number 11: Adopt Proposed Commercial
Under-Fired Charbroiling Emission Reduction Strategy,'' December 17,
2020.
---------------------------------------------------------------------------

    Notwithstanding being overdue in presenting these incentive-based
measures for board consideration, CARB and the District state that they
continue to assess and/or prepare the formal documentation for the
emission reductions from such incentive-based measures that could be
applied towards the aggregate tonnage commitments.\182\ For heavy-duty
trucks and off-road equipment, CARB acknowledges that many of the
project lives do not span the attainment year \183\ and, thus, while
these projects accelerate emission reductions and benefit communities
in the SJV, the projects that qualify for SIP credit may be limited for
the purposes of the 2012 annual PM2.5 NAAQS Serious area
attainment demonstration. Overall, the EPA anticipates that emission
reductions from such projects that qualify for SIP credit (``SIP-
creditable emission reductions'') may be smaller than originally
anticipated in the SJV PM2.5 Plan.
---------------------------------------------------------------------------

    \182\ 2021 Progress Report, 15 and 24.
    \183\ Id. at 24 and 32. Generally, mobile source incentive
projects implemented under the Carl Moyer program are under contract
only during the ``project life'' and may not be credited with SIP
emission reductions after the project life ends. EPA Region IX
``Technical Support Document for EPA's Rulemaking for the California
State Implementation Plan California Air Resources Board Resolution
19-26 San Joaquin Valley Agricultural Equipment Incentive Measure,''
February 2020, 12-13.
---------------------------------------------------------------------------

    CARB and the District point to certain measures that they
anticipate will provide more emission reductions than the original
emission reduction estimates (e.g., larger emission reductions from
Heavy-Duty I/M due to new 2019 state law requirements and new roadside
emissions monitoring) and the addition of the two substitute measures
(the Agricultural Burning Phase-out Measure (adopted) and the In-Use
Locomotive Measure (anticipated for CARB board consideration in 2022))
as compensating for incentive-based measures that may result in less
emission reductions than originally projected.\184\ In its annual
update to the Board on September 23, 2021, CARB staff explained that,
in light of the progress to-date on committed-to regulatory measures
and these two substitute measures, fewer incentive-based emission
reductions would be needed to demonstrate attainment of the 2012 annual
PM2.5 NAAQS.\185\ We further discuss the role of adopted
measures, measures not yet proposed for board consideration (including
incentive-based measures), and the substitute measures in the following
section of this proposed rule.
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    \184\ 2021 Progress Report, 30-31.
    \185\ CARB, ``Valley PM2.5 Implementation Update and
SIP Amendment,'' September 23, 2021, slides 22-25. Slide 25
illustrates a large decrease in the expected funding need from
approximately $5 billion over 2018-2025 to approximately $1 billion
over 2021-2025.

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

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

    First, on July 22, 2020, the EPA published its final approval of
the District's 2019 amendment to Rule 4901 \187\ and concurrently
credited this measure with annual average emission reductions of 0.2
tpd direct PM2.5 towards the District's PM2.5
tonnage commitment for 2024.\188\ As described in the EPA's March 27,
2020 proposed rule, this amount of SIP credit corresponded to a 75%
compliance rate (referred to as a ``rule effectiveness rate''),
consistent with the EPA's guidance on wood burning curtailment
programs,\189\ rather than a higher 100% rule effectiveness rate used
in the District's original calculations.\190\ In the 2021 Progress
Report, the State notes this conclusion in the EPA's July 22, 2020
final rule approving this measure into the SIP and now estimates
emission reductions of 0.2 tpd direct PM2.5 from this
measure.\191\ Consistent with the EPA's July 22, 2020 final rule, we
propose to credit this measure with annual average emission reductions
of 0.2 tpd direct PM2.5 for 2025 (i.e., to subtract 0.2 tpd
from the reductions of direct PM2.5 emissions that the
District is required to achieve with its PM2.5 tonnage
commitment).
---------------------------------------------------------------------------

    \187\ 85 FR 44206.
    \188\ 85 FR 44192, 44204.
    \189\ ``Strategies for Reducing Wood Smoke,'' EPA-456/B-13-01,
March 2013, 42.
    \190\ 85 FR 17382, 17415.
    \191\ 2021 Progress Report, 7 and Table 3.
---------------------------------------------------------------------------

    Second, on March 24, 2020, the EPA published its proposal to
approve the Agricultural Equipment Incentive Measure into the
California SIP,\192\ including projects funded through the Carl Moyer
Memorial Air Quality Standards Attainment Program (``Carl Moyer''),
Funding Agricultural Replacement Measures for Emission Reductions
(FARMER), and Natural Resources Conservation Service (NRCS) programs.
The measure includes commitments by CARB to monitor, assess, and report
on emission reductions, and to achieve emission reductions of 5.1 tpd
NOX and 0.3 tpd direct PM2.5 from the 2025
baseline inventory in the 2018 PM2.5 Plan by December 31,
2024.\193\ The EPA finalized a partial approval of this measure on
December 16, 2021, wherein the EPA credited 4.83 tpd NOX and
0.24 tpd direct PM2.5 towards CARB's tonnage commitments for
2024 (for attaining the 2006 24-hour PM2.5 NAAQS), and
calculated 4.46 tpd NOX and 0.26 tpd direct PM2.5
for 2025 (for attaining the 2012 annual PM2.5 NAAQS).\194\
---------------------------------------------------------------------------

    \192\ 85 FR 16588.
    \193\ EPA Region IX ``Technical Support Document for EPA's
Rulemaking for the California State Implementation Plan California
Air Resources Board Resolution 19-26 San Joaquin Valley Agricultural
Equipment Incentive Measure,'' February 2020, 4-5, 24-25, and 31.
    \194\ EPA Region IX, ``Air Plan Approval; San Joaquin Valley
Unified Air Pollution Control District,'' final rule signed December
16, 2021. The EPA deferred action on the NRCS portion of the
Agricultural Equipment Incentive Measure.
---------------------------------------------------------------------------

    Under longstanding guidance, the EPA has recommended presumptive
limits on the amounts of emission reductions from certain voluntary and
other nontraditional measures that may be credited in a SIP.
Specifically, for voluntary mobile source emission reduction programs,
the EPA has identified a presumptive limit of 3% of the additional
emission reductions (beyond reductions from baseline measures) required
to attain the appropriate NAAQS, and for any particular SIP submittal
to demonstrate attainment or maintenance of the NAAQS or progress
toward attainment (RFP), 3% of the specific statutory requirement.\195\
The EPA may, however, approve measures for SIP credit in amounts
exceeding the presumptive limits where a clear and convincing
justification is made by the State as to why a higher limit should
apply in a given case.\196\
---------------------------------------------------------------------------

    \195\ EPA, ``Guidance on Incorporating Voluntary Mobile Source
Emission Reduction Programs in State Implementation Plans (SIPs),''
October 24, 1997, 5.
    \196\ EPA, ``Incorporating Emerging and Voluntary Measures in a
State Implementation Plan (SIP),'' October 4, 2004, 9; see also EPA,
``Guidance on Incorporating Bundled Measures in a State
Implementation Plan,'' August 16, 2005, 8, n.6, and EPA, ``Diesel
Retrofit and Replacement Projects: Quantifying and Using Their
Emission Benefits in SIPs and Conformity: Guidance for State and
Local Air and Transportation Agencies,'' March 2018, 12.
---------------------------------------------------------------------------

    According to the State, the SJV's topography and meteorology
present significant challenges for air quality. As stated in the 2018
PM2.5 Plan, ``the surrounding mountains trap pollution and
block airflow'' and ``[t]emperature inversions, while present to some
degree throughout the year, can last for days during the winter,
holding in nighttime accumulations of pollutants.'' \197\ In addition,
the State notes that the population of the area continues to grow at a
rate higher than the statewide growth rate, leading to increased
vehicular traffic along major highways that run through the SJV.\198\
Given these unique challenges, both the State and District continue to
implement both traditional and non-traditional emission reduction
strategies to attain the PM2.5 standards in the SJV,

including regulatory programs, incentive programs, and rigorous
outreach and education efforts.\199\
---------------------------------------------------------------------------

    \197\ 2018 PM2.5 Plan, Ch. 2, 2-1.
    \198\ Id. at Ch. 2, 2-4.
    \199\ Id. at Ch. 2, 2-2.
---------------------------------------------------------------------------

    Over the past several decades, the State and District have
developed and implemented several comprehensive plans to address
attainment of the NAAQS for ozone and particulate matter.\200\ These
attainment plans have resulted in CARB and District's adoption of
numerous regulations for stationary, area, and mobile sources, many of
which are among the most stringent control measures in the nation.
Given the air quality needs of the area, the numerous control measures
that both the State and District have adopted and implemented in the
San Joaquin Valley to date, the State's and District's successful
implementation of the Carl Moyer program over the last two decades, and
our experience to date quantifying emission reductions achieved through
this program,\201\ we believe it is appropriate to allow the State to
rely on the Agricultural Equipment Incentive Measure to achieve 13.2%
(4.46 tpd) of the additional NOX reductions and 11.8% (0.26
tpd) of the additional direct PM2.5 reductions necessary for
the area to attain the 2012 annual PM2.5 NAAQS by the end of
2025.\202\ Moreover, all Carl Moyer and FARMER projects are subject to
detailed contract provisions that CARB may enforce against the grantee
at any time during the contract term, a program feature that further
supports the State's reliance on the Agricultural Equipment Incentive
Measure for emission reductions exceeding the EPA's presumptive
limits.\203\
---------------------------------------------------------------------------

    \200\ See, e.g., 69 FR 30005 (May 26, 2004) (approving plan to
attain the 1987 PM10 NAAQS), 76 FR 69896 (November 9,
2011) (partially approving and partially disapproving plan to attain
the 1997 PM2.5 NAAQS), 77 FR 12652 (March 1, 2012)
(approving plan to attain the 1997 8-hour ozone NAAQS), and 81 FR
19492 (April 5, 2016) (approving plan to attain the 1979 1-hour
ozone NAAQS).
    \201\ The EPA has approved two prior incentive-based SIP
submissions from CARB that rely on Carl Moyer projects for SIP
emission reduction credit. See 86 FR 3820 (January 15, 2021) (full
approval of South Coast incentive measure) and 81 FR 53300 (August
12, 2016) (limited approval/disapproval of ``Emission Reduction
Report'' for San Joaquin Valley).
    \202\ The EPA calculated these percentages based on the
additional emission reductions necessary to attain beyond the
baseline inventory for 2025: 4.46 tpd NOX/33.88 tpd
NOX = 13.2%; and 0.26 tpd direct PM2.5/2.2 tpd
direct PM2.5 = 11.8%.
    \203\ 2011 Carl Moyer Guidelines, Part I, Chapter 3, Section Y
(``Minimum Contract Requirements'') and 2017 Carl Moyer Guidelines,
Volume I, Part 1, Chapter 3, Section V (``Minimum Contract
Requirements''), para. 11 (``Repercussions for Nonperformance'').
---------------------------------------------------------------------------

    For purposes of the EPA's proposed rule on the Serious area plan
for the 2012 annual PM2.5 NAAQS, we propose to approve 4.46
tpd NOX and 0.26 tpd direct PM2.5 for the Carl
Moyer and FARMER portions of this measure towards CARB's tonnage
commitments for 2025 (for attaining the 2012 annual PM2.5
NAAQS).
    Third, CARB adopted the Lower Opacity Limits for Heavy-Duty
Vehicles measure as revisions to the Heavy-Duty Vehicle Inspection
Program (HDVIP) and Periodic Smoke Inspection Program (PSIP). CARB
estimated 1,170 tons of PM emissions benefits from the heavy-duty
trucking transportation sector from 2019 to 2025.\204\ CARB also
estimates that this measure will achieve 0.02 tpd direct
PM2.5 reductions by January 1, 2025.\205\ However, CARB has
not yet provided its analysis of the basis for this emission reduction
estimate. Therefore the EPA is not proposing at this time to credit
this measure with any particular amount of emission reductions towards
attainment of the 2012 annual PM2.5 NAAQS in the SJV.
---------------------------------------------------------------------------

    \204\ CARB, ``Proposed Amendments to the Heavy-Duty Vehicle
Inspection Program and Periodic Smoke Inspection Program, Staff
Report: Initial Statement of Reasons,'' release date April 3, 2018,
15. See also, EPA Region IX, ``Technical Support Document for EPA's
Rulemaking for the California State Implementation Plan, California
Air Resources Board--Title 13, Division 3, Chapter 3.5; Opacity
Testing of Heavy-Duty Diesel Vehicles,'' July 2021, 4.
    \205\ 2021 Progress Report, 16 and Table 2.
---------------------------------------------------------------------------

    Fourth, the Agricultural Burning Phase-out Measure is a significant
substitute measure that was not part of the State's original control
measure commitments. The Agricultural Burning Phase-out Measure, for
purposes of state law, was adopted by the District on June 17,
2021,\206\ and concurred upon by CARB on June 18, 2021,\207\ and later
adopted by the District on November 18, 2021, as a revision to the
California SIP.\208\ Previously, through Rule 4103 (``Open Burning''),
as amended April 15, 2010, the District restricted the type of
materials that may be burned and established other conditions and
procedures for open burning in conjunction with the District's Smoke
Management Program.\209\ The EPA approved Rule 4103 and the associated
table of the restrictions on open burning by crop category into the
California SIP on January 4, 2012.\210\ The District identifies Rule
4103 as a baseline measure in the 2018 PM2.5 Plan.\211\ The
Agricultural Burning Phase-out Measure, in turn, includes a schedule to
phase-out (i.e., introduce prohibitions of) agricultural burning for
additional crop categories or materials accounting for a vast majority
of the tonnage of agricultural waste in phases starting January 1,
2022, and becoming fully implemented by January 1, 2025.\212\ The
District estimates that this measure will achieve emission reductions
of 1.04 tpd NOX and 1.54 tpd direct PM2.5 in
2025.\213\
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    \206\ SJVUAPCD Resolution 21-06-12, June 17, 2021.
    \207\ Letter dated June 18, 2021, from Richard W. Corey,
Executive Officer, CARB, to Samir Sheikh, Executive Director,
SJVUAPCD.
    \208\ SJVUAPCD Resolution 21-11-7, November 18, 2021. See also,
Letter dated October 20, 2021, from Richard W. Corey, Executive
Officer, CARB, to Deborah Jordan, Acting Regional Administrator, EPA
Region IX.
    \209\ SJVUAPCD Rule 4103, as amended April 15, 2010.
    \210\ 77 FR 214 (January 4, 2012). The table of open burning
restrictions by crop category is codified at 40 CFR
52.220(c)(388)(i)(B)(3) Table 9-1, Revised Proposed Staff Report and
Recommendations on Agricultural Burning, approved by the District on
May 20, 2010.
    \211\ 2018 PM2.5 Plan, Chapter 4, tables 4-2 and 4-3,
and App. C.
    \212\ 2021 Supplemental Report and Recommendations, Table 2-1
(``Accelerated Reductions by Crop Category'').
    \213\ SJVUAPCD, ``District 4103 (Open Burning) Technical
Submittal for Receiving SIP Credit for Reductions in Agricultural
Burning,'' October 18, 2021, Table 6. See also, Progress Report,
Table 3.
---------------------------------------------------------------------------

    The EPA has evaluated this measure and has proposed to approve the
measure into the California SIP.\214\ The EPA considers the
Agricultural Burning Phase-out Measure to be an important new measure
given the phase-out structure of the measure for most remaining crop
categories and the large scale of agricultural activities that produce
such agricultural waste and burning thereof in the SJV. While the
District assumed a 100% rule effectiveness rate, the EPA noted our
general guideline of 80% rule effectiveness and that, notwithstanding
the statements in the 2021 Progress Report regarding the permitting
requirements for farming operations to burn their waste and the
enforceability of the measure, the District did not apply a rule
effectiveness rate nor address all the factors that are relevant to
determining such a rate.\215\ Therefore, the EPA proposes that an 80%
rule effectiveness is reasonable for this measure.
---------------------------------------------------------------------------

    \214\ EPA Region IX, ``Air Plan Approval; California; San
Joaquin Valley Unified Air Pollution Control District; Open
Burning,'' proposed rule signed December 16, 2021.
    \215\ EPA Region IX, ``Technical Support Document for EPA's
Rulemaking for the California State Implementation Plan, San Joaquin
Valley Unified Air Pollution Control District's Agricultural Burning
Phase-Out Measure,'' December 2021.
---------------------------------------------------------------------------

    For purposes of reviewing the Serious area plan for the 2012 annual
PM2.5 NAAQS, the EPA has reviewed the District's method for
calculating the emission reductions that this measure will achieve by
January 1, 2025.

Specifically, the District calculated the annual average emissions of
agricultural burning following full implementation of the phase-out
(i.e., by January 1, 2025), considering the tonnages of waste and
emission factors of each crop category (0.51 tpd NOX and
0.67 tpd direct PM2.5).\216\ The District then subtracted
these values (i.e., the additional reductions from the revised measure)
from the annual average emissions in the baseline emissions inventory
of the 2018 PM2.5 Plan for the 2025 attainment year (1.55
tpd NOX and 2.21 tpd direct PM2.5).\217\ The
resulting difference represents the annual average emission reductions
to be achieved by the measure (1.04 tpd NOX and 1.54 tpd
direct PM2.5).\218\
---------------------------------------------------------------------------

    \216\ Agricultural Burning Phase-out Measure, Table 6.
    \217\ Id. at Table 4. See also, 2018 PM2.5 Plan, C-15
(``Emissions Inventory'' table for open burning).
    \218\ Agricultural Burning Phase-out Measure, Table 6.
---------------------------------------------------------------------------

    The EPA proposes that this is an appropriate calculation method to
estimate the emission reductions from the Agricultural Burning Phase-
out Measure. It builds upon the baseline measure in the Plan for this
source category (i.e., Rule 4103, amended April 15, 2010, and Table 9-
1, adopted May 20, 2010), applies appropriate emission factors, and
identifies the difference between the Plan's baseline emissions and the
emissions that would remain following full implementation of the
measure. The January 1, 2025 deadline for final implementation is also
consistent with the implementation deadline under 40 CFR 51.1011(b)(5)
for control measures necessary for attainment by December 31, 2025.
However, the EPA proposes to apply an 80% rule effectiveness rate,
rather than the 100% rule effectiveness rate used in the District's
calculation.\219\ After applying this effectiveness rate, the EPA
proposes to credit this measure with emissions reductions of 0.83 tpd
NOX and 1.23 tpd direct PM2.5 in 2025 (i.e.,
subtract these values from the District's tonnage commitments for
2025). We provide further detail on this measure in sections III.B.1.a
and IV.B.3.e of the EPA's 2012 Annual PM2.5 TSD.
---------------------------------------------------------------------------

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

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

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

               Table 5--Reductions Needed for Attainment in 2025 and Aggregate Tonnage Commitments
----------------------------------------------------------------------------------------------------------------
                                                                                Direct PM2.5
                                                                                NOX  (tpd)         (tpd)

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

    Thus, at this time, we are not proposing to approve any particular
inter-pollutant trading approach for purposes of meeting the aggregate
tonnage commitments, nor applying any excess reductions of one
pollutant towards fulfilling a portion of committed reductions of the
other pollutant. Nevertheless, we note that because, as proposed, the
District's direct PM2.5 reductions have exceeded their
aggregate tonnage commitment, these excess reductions add a degree of
conservativeness to the combined attainment demonstration and control
plan. In light of the possibility of future interpollutant trading, we
have qualitatively evaluated the State's inter-pollutant trading
analysis as part of our assessment of the State's capability to fulfill
CARB and the District's aggregate tonnage commitments, as discussed
further in section IV.B.5 of the EPA's 2012 Annual PM2.5
TSD.
(e) Three-factor Test for Enforceable Commitments
    The EPA interprets the CAA to allow for approval of enforceable
commitments that are limited in scope where circumstances exist that
warrant the use of such commitments in place of adopted and submitted
measures.\241\ Specifically, CAA section 110(a)(2)(A) provides that
each SIP ``shall include enforceable emission limitations and other
control measures, means or techniques . . . as well as schedules and
timetables for compliance, as may be necessary or appropriate to meet
the applicable requirements of [the Act].'' Section 172(c)(6) of the
Act, which

applies to nonattainment SIPs, is virtually identical to section
110(a)(2)(A). The language in these sections of the CAA is broad,
allowing a SIP to contain any ``means or techniques'' that the EPA
determines are ``necessary or appropriate'' to meet CAA requirements,
such that the area will attain as expeditiously as practicable, but no
later than the designated date. Furthermore, the express allowance for
``schedules and timetables'' demonstrates that Congress understood that
all required controls might not have to be in place before a SIP could
be fully approved.
---------------------------------------------------------------------------

    \241\ Commitments approved by the EPA under CAA section
110(k)(3) are enforceable by the EPA and citizens under CAA sections
113 and 304, respectively. In the past, the EPA has approved
enforceable commitments and courts have enforced these actions
against states that failed to comply with those commitments. See,
e.g., American Lung Ass'n of N.J. v. Kean, 670 F. Supp. 1285 (D.N.J.
1987), aff'd, 871 F.2d 319 (3rd Cir. 1989); NRDC v. N.Y. State Dept.
of Env. Cons., 668 F. Supp. 848 (S.D.N.Y. 1987); Citizens for a
Better Env't v. Deukmejian, 731 F. Supp. 1448, recon. granted in
par, 746 F. Supp. 976 (N.D. Cal. 1990); Coalition for Clean Air v.
South Coast Air Quality Mgt. Dist., No. CV 97-6916-HLH, (C.D. Cal.
Aug. 27, 1999). Further, if a state fails to meet its commitments,
the EPA could make a finding of failure to implement the SIP under
CAA section 179(a), which starts an 18-month period for the State to
correct the non-implementation before mandatory sanctions are
imposed.
---------------------------------------------------------------------------

    Once the EPA determines that circumstances warrant consideration of
an enforceable commitment to satisfy a CAA requirement, it considers
three factors in determining whether to approve the enforceable
commitment: (a) Does the commitment address a limited portion of the
CAA requirement; (b) is the state capable of fulfilling its commitment;
and (c) is the commitment for a reasonable and appropriate period of
time.\242\
---------------------------------------------------------------------------

    \242\ The Fifth Circuit Court of Appeals upheld the EPA's
interpretation of CAA sections 110(a)(2)(A) and 172(c)(6) and the
Agency's use and application of the three factor test in approving
enforceable commitments in the 1-hour ozone SIP for Houston-
Galveston. BCCA Appeal Group v. EPA, 355 F.3d 817 (5th Cir. 2003).
More recently, the Ninth Circuit Court of Appeals upheld the EPA's
approval of enforceable commitments in ozone and PM2.5
SIPs for the SJV, based on the same three factor test. Committee for
a Better Arvin v. EPA, 786 F.3d 1169 (9th Cir. 2015).
---------------------------------------------------------------------------

    With respect to the SJV PM2.5 Plan, circumstances
warrant the consideration of enforceable commitments as part of the
attainment demonstration for this area. As shown in Table 5 of this
proposed rule, the majority of the emissions reductions needed to
demonstrate attainment and RFP in the SJV are achieved by rules and
regulations adopted prior to the State's development of the SJV
PM2.5 Plan, i.e., baseline measures. As a result of these
already-adopted CARB and District measures, most air pollution sources
in the SJV were already subject to stringent rules prior to the
development of the SJV PM2.5 Plan, leaving fewer and more
technologically-challenging opportunities to reduce emissions. Despite
these significant emission reductions, as shown in Table 4 of this
proposed rule, the State needs to reduce NOX and direct
PM2.5 emission levels by a total of 65.4% and 10.2%,
respectively, from 2013 base year levels in order to attain the 2012
annual PM2.5 NAAQS by the end of 2025 in the SJV.
    As part of their respective control measure commitments in the SJV
PM2.5 Plan, CARB and the District identified potential
control measures that they expected to achieve the additional emissions
reductions needed for attainment. The timeline needed to develop,
adopt, and implement these measures extended beyond the year of Plan
adoption, with most measures originally scheduled for board
consideration in 2019, 2020, and 2021. Both CARB and the District have
made substantial progress in adopting the rules and measures listed in
their respective control measure commitments, as well as one important
substitute measure, but have not yet completely fulfilled the control
measure commitments. Given these circumstances, we conclude that CARB
and District's reliance on enforceable commitments in the SJV
PM2.5 Plan is warranted. Therefore, we have considered the
three factors the EPA uses to determine whether the use of enforceable
commitments in lieu of adopted measures satisfies CAA planning
requirements.
(1) The Commitment Represents a Limited Portion of Required Reductions
    For the first factor, we look to see if the commitment addresses a
limited portion of a statutory requirement, such as the amount of
emissions reductions needed to attain the NAAQS in a nonattainment
area. As shown in Table 5 of this proposed rule, most of the total
emission reductions needed to attain the 2012 annual PM2.5
NAAQS in the SJV by the end of 2025 will be achieved through
implementation of baseline measures and additional measures for which
the EPA has finalized or proposed approval, leaving 13.8% (28.59 tpd)
of the necessary NOX reductions and 8.0% (0.51 tpd) of the
necessary direct PM2.5 reductions as aggregate tonnage
commitments.
    Given the nature of the PM2.5 challenge in the SJV, the
significant reductions in NOX and direct PM2.5
emission levels achieved through implementation of baseline measures
over the past several decades, and the difficulty of identifying
additional control measures that are feasible for implementation in the
area, we consider it reasonable for CARB and District to seek
additional time to develop and adopt the last increment of emission
reductions necessary for attainment by 2025.
    Therefore, we conclude that the emission reductions remaining as
enforceable commitments in the SJV PM2.5 Plan represent a
limited portion of the total emissions reductions needed to demonstrate
attainment of the 2012 annual PM2.5 NAAQS by December 31,
2025.
(2) The State Is Capable of Fulfilling Its Commitment
    For the second factor, we consider whether the State and District
are capable of fulfilling their commitments. As discussed in section
IV.F.3.c of this proposed rule and shown in tables IV.A and IV.B of the
EPA's 2012 Annual PM2.5 TSD, the EPA notes that CARB and the
District have made substantial progress in developing and adopting the
regulatory measures listed in their respective control measure
commitments. Specifically, CARB and the District have adopted 18
measures of the 27 control measure commitments in the SJV
PM2.5 Plan. CARB has adopted 10 measures (including one
incentive-based measure) and begun the public process on 3 of the
remaining 5 measures. The adopted measures include, for example, Heavy-
Duty I/M, the California Heavy-Duty Low-NOX Engine Standard,
the SORE regulation, and the Agricultural Equipment Incentive Measure.
    The District has adopted eight measures (including one incentive-
based measure) and begun the public process on two of the remaining
four measures. The adopted measures include, for example, amendments to
Rule 4311 (``Flares''), Rule 4702 (``Internal Combustion Engines''),
and Rule 4901 (``Woodburning Fireplaces and Wood Burning Heaters'')
(Hot-spot strategy), and the Residential Wood Burning Devices Incentive
Projects measure.
    As discussed in section IV.3.d of this proposed rule, the remaining
aggregate tonnage commitments sum to 28.59 tpd NOX and 0.51
tpd direct PM2.5. We also note that, pending final approval
of the Agricultural Burning Phase-out Measure, that the District will
have met its 1.3 tpd direct PM2.5 commitment and, in fact,
exceeded it by 0.13 tpd. Based on our review of the State's 2021
Progress Report, CARB has adopted 10 additional measures and advanced
their development and analysis of two additional measures of the Plan's
original control measure commitments (one slated for board
consideration in 2022 and one as early as 2022), and also developed a
substitute measure (slated for board consideration in 2022). Similarly,
beyond the two adopted measures (Rule 4901 and the Agricultural Burning
Phase-out Measure) that the EPA proposes to credit towards the
aggregate tonnage commitments, the District has adopted seven
additional measures.
    The updated emission reduction estimates for this series of
additional CARB and District measures sum to

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

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

    Beyond the measures discussed above, both CARB and the District
have well-established incentive grant programs to reduce emissions from
mobile, stationary, and area sources in the SJV. Funding for the
State's incentive programs in the SJV comes from various sources
including the Carl Moyer Program, Proposition 1B Goods Movement
Emission Reduction Program, Greenhouse Gas Reduction Fund, and the
Funding Agricultural Replacement Measures for Emission Reductions
(FARMER) program.\244\ Funding for the District's incentive programs
comes from a combination of federal, State, and local funding
mechanisms, including the Diesel Emission Reduction Act (DERA) and
Target Airshed Grant programs, the Carl Moyer program, and fees
assessed in the SJV by the California Department of Motor Vehicles and
by the District through programs for Indirect Source Review, Voluntary
Emission Reduction Agreements, and large boilers, steam generators, and
process heaters.\245\
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    \244\ 2018 PM2.5 Plan, App. E, E-6.
    \245\ Id.
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    Collectively, these incentive funds have been applied to a wide
range of emission sources, including heavy-duty trucks, light-duty
vehicles, mobile agricultural equipment, locomotives, school buses,
alternative fuel infrastructure, community-based programs, agricultural
irrigation pumps, residential wood combustion devices, and commercial
charbroilers.\246\ The Plan identifies the total funding need for
expeditious attainment as $5 billion, including $3.3 billion for heavy-
duty trucks and buses and $1.4 billion for mobile agricultural
equipment.\247\
---------------------------------------------------------------------------

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

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

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

    More broadly, whether for regulatory measures or incentive-based
measures, we note also that CARB and the District will have to submit
to the EPA, for SIP approval, any control measure that it intends to
rely on to satisfy the aggregate tonnage commitments in the Plan.
Furthermore, where CARB or the District intend to substitute reductions
in one pollutant to achieve a tonnage commitment concerning a different
pollutant (e.g., substituting direct PM2.5 reductions to
satisfy a NOX reduction commitment), it must include an
appropriate inter-pollutant trading (IPT) ratio and the technical basis
for such ratio. The EPA will review any such IPT ratio and its bases
before approving or disapproving the measure.
    Given CARB and the District's progress in adopting 18 measures to
date, their substantial progress toward achieving the aggregate tonnage
commitments, including the District having met and exceeded its direct
PM2.5 commitment, their ongoing efforts to develop
additional measures, and their stated intent to continue to fulfill
their respective commitments, we propose that CARB and the District are
capable of fulfilling the remaining increment of NOX
emission reductions necessary to attain the 2012 annual
PM2.5 NAAQS in the SJV by December 31, 2025.
(3) The Commitment is for a Reasonable and Appropriate Timeframe
    For the third factor, we consider whether the commitment is for a
reasonable and appropriate period of time. As discussed in section II.B
of this proposed rule, on March 23, 2017, CARB adopted the 2016 State
Strategy and directed staff to return to the Board with a commitment to
achieve additional emission reductions from

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

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

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

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

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

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

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

G. Reasonable Further Progress and Quantitative Milestones

1. Requirements for Reasonable Further Progress and Quantitative
Milestones
    Section 172(c)(2) of the Act provides that all nonattainment area
plans shall require reasonable further progress (RFP) toward
attainment. In addition, CAA section 189(c) requires that all
PM2.5 nonattainment area plans contain quantitative
milestones for purposes of measuring RFP, as defined in CAA section
171(1), every three years until the EPA redesignates the area to
attainment. Section 171(1) of the Act defines RFP as the annual
incremental reductions in emissions of the relevant air pollutant as
are required by part D, title I of the Act, or as may reasonably be
required by the Administrator for the purpose of ensuring attainment of
the NAAQS by the applicable attainment date. Neither subpart 1 nor
subpart 4 of part D, title I of the Act requires that states achieve a
set percentage of emissions reductions in any given year for purposes
of satisfying the RFP requirement.
    For purposes of the particulate matter NAAQS, RFP has historically
been met by showing annual incremental emissions reductions sufficient
to maintain ``generally linear progress'' toward attainment by the
applicable deadline.\257\ As discussed in EPA guidance in the General
Preamble Addendum, requiring generally linear progress in reductions of
direct PM and relevant PM precursors in an attainment plan may be
appropriate in situations where:
---------------------------------------------------------------------------

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

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

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

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

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

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

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

    Plans for PM nonattainment areas should include detailed schedules
for compliance with emission control measures in the area and provide
corresponding annual emission reductions to be achieved by each
milestone in the schedule.\261\ In reviewing an attainment plan under
subpart 4, the EPA considers whether the annual incremental emissions
reductions to be achieved are reasonable in light of the statutory
objective of timely attainment. Although early implementation of the
most cost-effective control measures is often appropriate, states
should consider both cost-effectiveness and pollution reduction
effectiveness when developing implementation schedules for control
measures, and may implement measures that are more effective at
reducing PM earlier to provide greater public health benefits.\262\
---------------------------------------------------------------------------

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

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

PM, the Agency has established specific regulatory requirements for the
PM2.5 NAAQS in the PM2.5 SIP Requirements Rule
for purposes of satisfying the Act's RFP requirements and provided
related guidance in the preamble to the rule. Specifically, under the
PM2.5 SIP Requirements Rule, each PM2.5
attainment plan must contain an RFP analysis that includes, at minimum,
the following four components: (1) An implementation schedule for
control measures; (2) RFP projected emissions for direct
PM2.5 and all PM2.5 plan precursors for each
applicable milestone year, based on the anticipated control measure
implementation schedule; (3) a demonstration that the control strategy
and implementation schedule will achieve reasonable progress toward
attainment between the base year and the attainment year; and (4) a
demonstration that by the end of the calendar year for each triennial
milestone date for the area, pollutant emissions will be at levels that
reflect either generally linear progress or stepwise progress in
reducing emissions on an annual basis between the base year and the
attainment year.\263\
---------------------------------------------------------------------------

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

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

    \264\ 40 CFR 51.1012(a)(4).
    \265\ 81 FR 58010, 58057.
    \266\ Id. at 58056.
---------------------------------------------------------------------------

    Section 189(c) of the Act requires that PM2.5 attainment
plans include quantitative milestones that demonstrate RFP. The purpose
of the quantitative milestones is to allow periodic evaluation of the
area's progress towards attainment of the PM2.5 NAAQS
consistent with RFP requirements. Because RFP is an annual emission
reduction requirement and the quantitative milestones are to be
achieved every three years, when a state demonstrates compliance with
the quantitative milestone requirement, it should also demonstrate that
RFP has been achieved during each of the relevant three years.
Quantitative milestones should provide an objective means to evaluate
progress toward attainment meaningfully, e.g., through imposition of
emissions controls in the attainment plan and the requirement to
quantify those required emissions reductions. The CAA also requires a
state to submit, within 90 days after each three-year quantitative
milestone date, a milestone report that includes technical support
sufficient to document completion statistics for appropriate
milestones, e.g., the calculations and any assumptions made concerning
emission reductions to date.\267\
---------------------------------------------------------------------------

    \267\ CAA section 189(c)(2) and 40 CFR 51.1013(b). See also,
PM2.5 SIP Requirements Rule, 58065 and General Preamble
Addendum, 42016, 42017.
---------------------------------------------------------------------------

    The CAA does not specify the starting point for counting the three-
year periods for quantitative milestones under CAA section 189(c). In
the General Preamble and General Preamble Addendum, the EPA interpreted
the CAA to require that the starting point for the first three-year
period be the due date for the Moderate area plan submission.\268\
Consistent with this longstanding interpretation of the Act, the
PM2.5 SIP Requirements Rule requires that each plan for a
Serious PM2.5 nonattainment area that demonstrates
attainment by the end of the 10th calendar year following the date of
designation contain quantitative milestones to be achieved no later
than milestone dates 7.5 years and 10.5 years from the date of
designation of the area.\269\ The 2018 PM2.5 Plan includes a
demonstration of attainment by the end of the 10th calendar year
following designations (i.e., December 31, 2025). Because the EPA
designated the SJV nonattainment for the 2012 annual PM2.5
NAAQS effective April 15, 2015,\270\ the applicable quantitative
milestone dates for purposes of the submitted Serious area plan for
this NAAQS in the SJV are October 15, 2022, and October 15, 2025.
---------------------------------------------------------------------------

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

    Quantitative milestones must provide for objective evaluation of
reasonable further progress toward timely attainment of the
PM2.5 NAAQS in the area and include, at minimum, a metric
for tracking progress achieved in implementing SIP control measures,
including BACM and BACT, by each milestone date.\271\
---------------------------------------------------------------------------

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

2. Summary of State's Submission
    Appendix H (``RFP, Quantitative Milestones, and Contingency'') of
the 2018 PM2.5 Plan contains the State's RFP demonstration
and quantitative milestones for the 2012 annual PM2.5 NAAQS.
Following the identification of a transcription error in the RFP tables
of Appendix H, the State submitted a revised version of Appendix H that
corrects the transcription error and provides additional information on
the RFP demonstration.\272\ Given the State's conclusions that ammonia,