18; 2018 PM2.5 Plan, App. K, 48ff, tables 20 through 23.
    \123\ 2016 PM2.5 Plan, App. A, 107ff, Supplemental
materials, Figures S.37-S.52; 2018 PM2.5 Plan, App. K,
131ff, Supplemental materials, Figures S.41-S.52.
    \124\ 2016 PM2.5 Plan, App. A, 46, Figure 13; 2018
PM2.5 Plan, App. K, 54, Figure 14.
---------------------------------------------------------------------------

    The high days are generally captured by the model, even though some
are underpredicted in December at certain monitoring sites such as
Fresno. Overall, the modeled site maxima are comparable to the
measurements; also, the frequency of high and low days generally
matches observations so the annual as well as the daily model
performance is acceptable.
    The EPA evaluated the State's choice of model for the
impracticability demonstration and the extensive discussion in the 2016
PM2.5 Plan about modeling procedures, tests, and performance
analyses, as well as the State's modeling choices, procedures, test,
and performance analyses in the 2018 PM2.5 Plan.\125\ We
find the State's analyses consistent with the EPA's guidance on
modeling for PM2.5 attainment planning purposes. Based on
these reviews, we find that the modeling in the 2016 PM2.5
Plan and 2018 PM2.5

Plan is adequate for the purposes of supporting the RFP demonstration
and the demonstration of impracticability in the 2016 PM2.5
Plan.
---------------------------------------------------------------------------

    \125\ For a more detailed summary of the State's air quality
modeling in the 2018 PM2.5 Plan with respect to the 2006
24-hour PM2.5 NAAQS, rather than the 2012 annual
PM2.5 NAAQS, please refer to the EPA's 2006 NAAQS
Modeling TSD.
---------------------------------------------------------------------------

D. Reasonably Available Control Measures and Control Strategy

1. Requirements for RACM/RACT and Control Strategies
    The general subpart 1 attainment plan requirement for RACM/RACT is
described in CAA section 172(c)(1), which requires that attainment plan
submissions ``provide for the implementation of all reasonably
available control measures as expeditiously as practicable (including
such reductions in emissions from existing sources in the area as may
be obtained through the adoption, at a minimum, of reasonably available
control technology)'' and provide for attainment of the NAAQS.
    The attainment planning requirements specific to PM2.5
under subpart 4 likewise impose an obligation upon states with
nonattainment areas classified as Moderate to develop attainment plans
that require RACM/RACT on sources of direct PM2.5 and all
PM2.5 plan precursors. CAA section 189(a)(1)(C) requires
that Moderate area PM2.5 SIPs contain provisions to assure
that RACM/RACT are implemented no later than four years after
designation of the area. The EPA reads CAA section 172(c)(1) and
189(a)(1)(C) together to require that attainment plans for Moderate
nonattainment areas provide for the implementation of RACM/RACT for
existing sources of PM2.5 and those PM2.5
precursors subject to control in the nonattainment area as
expeditiously as practicable but no later than four years after
designation.\126\
---------------------------------------------------------------------------

    \126\ This interpretation is consistent with guidance provided
in the General Preamble, 13540.
---------------------------------------------------------------------------

    The PM2.5 SIP Requirements Rule defines RACM as ``any
technologically and economically feasible measure that can be
implemented in whole or in part within 4 years after the effective date
of designation of a PM2.5 nonattainment area and that
achieves permanent and enforceable reductions in direct
PM2.5 emissions and/or PM2.5 plan precursor
emissions from sources in the area. RACM includes reasonably available
control technology (RACT).'' \127\ The EPA has historically defined
RACT as the lowest emission limitation that a particular stationary
source is capable of meeting by the application of control technology
that is reasonably available considering technological and economic
feasibility.\128\
---------------------------------------------------------------------------

    \127\ 81 FR 58010, 58035.
    \128\ General Preamble, 13541 and 57 FR 18070, 18073-18074.
---------------------------------------------------------------------------

    Under the PM2.5 SIP Requirements Rule, those control
measures that otherwise meet the definition of RACM but ``can only be
implemented in whole or in part during the period beginning 4 years
after the effective date of designation of a nonattainment area and no
later than the end of the sixth calendar year following the effective
date of designation of the area'' must be adopted and implemented as
``additional reasonable measures.'' \129\
---------------------------------------------------------------------------

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

    States must provide written justification in a SIP submission for
eliminating potential control options from further review on the basis
of technological or economic infeasibility.\130\ An evaluation of
technological feasibility may include consideration of factors such as
a source's process and operating conditions, raw materials, physical
plant layout, and non-air quality and energy impacts (e.g., increased
water pollution, waste disposal, and energy requirements).\131\ An
evaluation of economic feasibility may include consideration of factors
such as cost per ton of pollution reduced (cost-effectiveness), capital
costs, and operating and maintenance costs.\132\ Absent other
indications, the EPA presumes that it is reasonable for similar sources
to bear similar costs of emission reductions. Economic feasibility of
RACM/RACT is thus largely informed by evidence that other sources in a
source category have in fact applied the control technology, process
change, or measure in question in similar circumstances.\133\
---------------------------------------------------------------------------

    \130\ 40 CFR 51.1009(a)(3).
    \131\ 40 CFR 51.1009(a)(3); see also 57 FR 18070, 18073-18074.
    \132\ Id.
    \133\ 57 FR 18070, 18074.
---------------------------------------------------------------------------

    Consistent with these requirements, CARB and SJVUAPCD must
implement RACM, including RACT, for sources of direct PM2.5
and PM2.5 plan precursors no later than April 15, 2019, and
must implement additional reasonable measures for these sources no
later than December 31, 2021.
2. Summary of State's Control Strategy
    The RACM/RACT evaluation for sources of direct PM2.5 and
NOX emissions in the SJV area is presented in Chapter 3 of
the 2016 PM2.5 Plan and in Attachment 1 and Attachment 2 to
the 2016 PM2.5 Plan. Attachment 1 to the 2016
PM2.5 Plan contains (1) a copy of the BACM/BACT and MSM
control strategy evaluation for stationary and area sources that the
District adopted on April 16, 2015, as part of its ``2015 Plan for the
1997 PM2.5 Standard'' (``2015 PM2.5 Plan''), and
(2) a copy of the RACM/RACT control strategy evaluation for stationary
and area sources that the District adopted on June 16, 2016, as part of
its ``2016 Plan for the 2008 8-Hour Ozone Standard'' (``2016 Ozone
Plan'').\134\ Attachment 2 to the 2016 PM2.5 Plan contains
(1) a copy of the BACM/BACT and MSM control strategy evaluation for
mobile sources that CARB adopted on May 21, 2015, as part of the 2015
PM2.5 Plan, and (2) a copy of the RACM/RACT control strategy
evaluation for mobile sources that CARB adopted on July 21, 2016, as
part of the 2016 Ozone Plan.\135\
---------------------------------------------------------------------------

    \134\ 2016 PM2.5 Plan, Attachment 1 (comprising 2015
PM2.5 Plan, App. C (``BACM and MSM for Stationary and
Area Sources'')) and 2016 Ozone Plan, App. C (``Stationary and Area
Source Control Strategy Evaluations''). See also SJVUAPCD Governing
Board Resolution 15-4-7A, April 16, 2015 (adopting the 2015
PM2.5 Plan) and SJVUAPCD Governing Board Resolution 16-6-
20, June 16, 2016 (adopting the 2016 Ozone Plan).
    \135\ 2016 PM2.5 Plan, Attachment 2 (comprising 2015
PM2.5 Plan, App. D (``BACM and MSM for Mobile Sources
(Provided by ARB)'') and 2016 Ozone Plan, App. D (``Mobile Source
Control Strategy''). See also CARB Resolution 15-9, May 21, 2015
(adopting the 2015 PM2.5 Plan) and CARB Resolution 16-8,
July 21, 2016 (adopting the 2016 Ozone Plan).
---------------------------------------------------------------------------

    The 2015 PM2.5 Plan and 2016 Ozone Plan contain
comprehensive analyses to identify potential emission reduction
opportunities for sources of direct PM2.5 and NOX
emissions and to determine whether additional measures would be
technologically and economically feasible for implementation in the
SJV.\136\ The District states in the 2016 PM2.5 Plan that it
has not identified any new emission control technologies that could
further reduce emissions in the SJV area, that the cost of technologies
recently found not to be cost-effective has not changed, and that
potential additional measures remain economically infeasible,
consistent with the analyses and conclusions in the 2015
PM2.5 Plan and the 2016 Ozone Plan.\137\ Based on these
analyses, the District concludes that the 2016 PM2.5 Plan
satisfies the RACM/RACT requirement for stationary and area sources of
direct PM2.5 and NOX emissions. The 2018
PM2.5 Plan, submitted May 10, 2019, supplements these
analyses by providing updated evaluations of potential control measures
for sources of direct PM2.5 and NOX emissions and
the District's rationale for finding that additional

control measures are not technologically and economically feasible for
implementation in the SJV.\138\
---------------------------------------------------------------------------

    \136\ 2016 PM2.5 Plan, Ch. 3, 3-5 to 3-6.
    \137\ Id.
    \138\ 2018 PM2.5 Plan, App. C (``Stationary Source
Control Measure Analyses'').
---------------------------------------------------------------------------

    With respect to mobile sources, the 2016 PM2.5 Plan
states that CARB has implemented the most stringent mobile source
emissions control program in the nation, including emission standards
for new vehicles, in-use programs for exiting vehicles and fleets,
cleaner fuels, and incentive programs to accelerate penetration of
cleanest vehicles.\139\ CARB states that its analyses of these mobile
source control measures are presented in the 2015 PM2.5 Plan
and the 2016 Ozone Plan (included as Attachment 2 to the 2016
PM2.5 Plan) and states that there are no additional
reasonably available control measures that would advance attainment of
the PM2.5 NAAQS in the SJV.\140\ Based on these analyses,
CARB concludes that the 2016 PM2.5 Plan satisfies the RACM/
RACT requirement for mobile sources of direct PM2.5 and
NOX emissions. The 2018 PM2.5 Plan, submitted May
10, 2019, supplements these analyses by providing updated evaluations
of CARB's mobile source control measures and its rationale for finding
that additional control measures are not technologically and
economically feasible for implementation in the SJV at this time.\141\
---------------------------------------------------------------------------

    \139\ 2016 PM2.5 Plan, 3-6.
    \140\ CARB 2016 Staff Report, 13.
    \141\ 2018 PM2.5 Plan, App. D (``Mobile Source
Control Measure Analyses'').
---------------------------------------------------------------------------

    Finally, with respect to transportation control measures (TCMs),
the 2016 PM2.5 Plan states that the eight county
metropolitan planning organizations (MPOs) of the SJV (``SJV MPOs'')
identified and evaluated all TCMs during development of the plan.\142\
The plan states that the SJV MPOs implement TCMs in CAA section 108(f)
consistent with the Congestion Mitigation and Air Quality cost
effectiveness policy when developing each MPO's Regional Transportation
Plan. In 2016 the Valley MPOs revisited the minimum cost effectiveness
standard for TCMs during the development of the MPOs' 2017 Federal
Transportation Improvement Program.\143\ The District concludes that
the Valley MPOs are implementing all reasonable TCMs under the MPOs'
jurisdictions and that adoption of additional TCMs would not expedite
attainment of the 2012 PM2.5 NAAQS in the SJV.\144\ The 2018
PM2.5 Plan, submitted May 10, 2019, supplements these
analyses by providing an updated discussion of the transportation
control measures being implemented in the SJV.\145\
---------------------------------------------------------------------------

    \142\ 2016 PM2.5 Plan, 3-6.
    \143\ 2016 PM2.5 Plan, 3-23 to 3-24. See also 2016
PM2.5 Plan, Attachment 2, App. D, section D.2.2 (D-16
through D-18) and Attachment D (``Adopted Transportation Control
Measures'').
    \144\ 2016 PM2.5 Plan, 3-6.
    \145\ 2018 PM2.5 Plan, App. D, D-127 to D-128 (noting
that the MPOs revisited the minimum cost effectiveness standard
during the development of their 2018 Regional Transportation Plans
and 2019 Federal Transportation Improvement Program and concluded
that they were implementing all reasonable transportation control
measures).
---------------------------------------------------------------------------

3. EPA's Evaluation and Proposed Action
    We have reviewed the State and District's demonstrations in the
2016 PM2.5 Plan concerning RACM/RACT and additional
reasonable measures for mobile, stationary, and area sources of direct
PM2.5 and one PM2.5 plan precursor (i.e.,
NOX) in the SJV. Our evaluation relies primarily on our
previous evaluations of the State and District rules in connection with
our February 12, 2019 approval of the SJV RACM demonstration for the
2008 ozone NAAQS (for NOX emission sources) \146\ and in
connection with our July 22, 2020 approval of the State and District's
demonstrations to meet the BACM (including BACT) and MSM requirements
for the 2006 PM2.5 NAAQS.\147\ We provide a detailed
discussion of these evaluations in the technical support document for
this proposed rule.\148\ Based on these reviews, we propose to find
that the District's rules provide for the implementation of RACM and
additional reasonable measures \149\ for stationary and area sources of
direct PM2.5 and NOX and that CARB's current
program implements RACM and additional reasonable measures for mobile
sources of direct PM2.5 and NOX emissions for
purposes of the 2012 PM2.5 NAAQS in the SJV.
---------------------------------------------------------------------------

    \146\ 84 FR 3302.
    \147\ 85 FR 44192 (final rule approving 2018 PM2.5
Plan as meeting, inter alia, BACM/BACT and MSM requirements for 2006
PM2.5 NAAQS). Because the RACM/RACT and additional
reasonable measure control strategy in the 2016 PM2.5
Plan is very similar to the BACM/BACT and MSM control strategy in
the 2018 PM2.5 Plan, and because the State's and
District's control measure evaluations in the 2016 PM2.5
Plan substantially overlap with their BACM/BACT and MSM control
evaluations in the 2018 PM2.5 Plan, we rely primarily on
our evaluation of the State's and District's BACM/BACT and MSM
control measure evaluations in the 2018 PM2.5 Plan (see
proposed rule, 85 FR 17382 (March 27, 2020) and final rule, 85 FR
44192) to support our evaluation of the RACM/RACT and additional
reasonable measure control strategy in the 2016 PM2.5
Plan.
    \148\ EPA, Region IX, Air Division, ``Technical Support
Document, EPA Evaluation of RACM/RACT and Additional Reasonable
Measures, San Joaquin Valley Moderate Area Plan for the 2012
PM2.5 NAAQS,'' August 2021.
    \149\ The 2018 PM2.5 Plan identifies Rule 4901
(``Wood Burning Fireplaces and Wood Burning Heaters''), as amended
June 20, 2019, as an additional reasonable measure that is scheduled
for implementation beginning in 2020. 2018 PM2.5 Plan,
Table 4-4 (``Proposed Regulatory Measures''). The EPA approved Rule
4901 into the California SIP on July 22, 2020. 85 FR 44206 (final
rule approving Rule 4901) and 85 FR 44192 (determination that Rule
4901 implements BACM and MSM for residential wood burning).
---------------------------------------------------------------------------

    With respect to transportation controls, we find that the SJV MPOs
have well-established TCM development programs in which TCMs are
continuously identified, reviewed, and evaluated throughout the
transportation planning process. Overall, we believe that the programs
developed and administered by CARB and the SJV MPOs provide for the
implementation of RACM and additional reasonable measures for sources
of direct PM2.5 and NOX in the SJV.
    For these reasons, we propose to find that the 2016
PM2.5 Plan provides for the implementation of RACM and
additional reasonable measures for all sources of direct
PM2.5 and NOX as expeditiously as practicable,
for purposes of implementing the 2012 PM2.5 NAAQS in the SJV
in accordance with the requirements of CAA section 189(a)(1)(C) and 40
CFR 51.1009.

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

    Section 189(e) of the CAA specifically requires that the control
requirements applicable to major stationary sources of direct
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.\150\ The control
requirements applicable to major stationary sources of direct
PM2.5 in a Moderate PM2.5 nonattainment area
include, at a minimum, the requirements of an NNSR permit program
meeting the requirements of CAA sections 172(c)(5) and 189(a)(1)(A). In
the PM2.5 SIP Requirements Rule, we established a deadline
for states to submit NNSR plan revisions to implement the
PM2.5 NAAQS 18 months after an area is initially designated
and classified as a Moderate nonattainment area.\151\
---------------------------------------------------------------------------

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

    California submitted NNSR SIP revisions for the SJV to address the
subpart 4 requirements for Moderate PM2.5 nonattainment
areas on May 19,

2011.\152\ The EPA fully approved these SIP revisions on September 17,
2014.\153\ California also submitted NNSR SIP revisions for the SJV to
address the subpart 4 requirements for Moderate and Serious
PM2.5 nonattainment areas on November 20, 2019. The EPA is
evaluating this SIP submission and will act on it in a separate
rulemaking. Accordingly, in this action, the EPA is not addressing the
NNSR control requirements that apply to major stationary sources of
direct PM2.5 and PM2.5 precursors in the SJV
under CAA section 189(e).
---------------------------------------------------------------------------

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

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

1. Requirements for Attainment/Impracticability of Attainment
Demonstrations
    Section 189(a)(1)(B) of the CAA requires that each Moderate area
attainment plan include a demonstration that the plan provides for
attainment by the applicable Moderate area attainment date or,
alternatively, that attainment by such date is impracticable. This
provision explicitly requires that a demonstration of attainment be
based on air quality modeling but does not require such modeling for an
impracticability demonstration. Although the EPA expects that most
impracticability demonstrations will also be supported by air quality
modeling, it may be possible in some cases to support an
impracticability demonstration with ambient PM2.5 data and
other relevant non-modeling information.\154\
---------------------------------------------------------------------------

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

    Section 188(c) of the CAA states, in relevant part, that the
Moderate area attainment date ``shall be as expeditiously as
practicable but no later than the end of the sixth calendar year after
the area's designation as nonattainment . . . .'' For the SJV, which
was initially designated as nonattainment for the 2012 PM2.5
standard effective April 15, 2015, the applicable Moderate area
attainment date under section 188(c) for this standard is as
expeditiously as practicable but no later than December 31, 2021.
    In SIP submissions that demonstrate impracticability, the state
should document how its required control strategy in the attainment
plan represents the application of RACM/RACT and additional reasonable
measures, at minimum, to existing sources. The EPA believes it is
appropriate to require adoption of all available control measures that
are reasonable, i.e., technologically and economically feasible, in
areas that do not demonstrate timely attainment, even where those
measures cannot be implemented within the 4-year timeframe for
implementation of RACM/RACT under CAA section 189(a)(1)(C). The
impracticability demonstration will then be based on a showing that the
area cannot attain by the applicable attainment date, notwithstanding
implementation of the required controls.
2. Summary of State's Impracticability Demonstration
    The 2016 PM2.5 Plan includes a demonstration, based on
air quality modeling, that even with the implementation of RACM/RACT
and additional reasonable measures for all appropriate sources,
attainment by December 31, 2021, is not practicable. The
impracticability demonstration is included in Appendix A of the 2016
PM2.5 Plan. As described in section IV.C.2 of this proposed
rule, the projected 2021 control scenario design value is 14.8
[micro]g/m\3\ at Bakersfield-Planz, which is typically the monitoring
site that records the highest PM2.5 levels in the SJV.
    As further described in section IV.C.2 of this proposed rule, the
2018 PM2.5 Plan includes a modeled demonstration that
projects annual PM2.5 concentrations in 2020 that provides
additional information on which to judge the practicability of
attaining by 2021 in that it is the closest analysis year available and
represents modeling based on updated data. These projections lend
support for the 2016 PM2.5 Plan conclusion that the 2012
annual PM2.5 standard will not be met in the SJV in 2021.
    Table 3 shows the projected annual PM2.5 concentrations
at the four PM2.5 monitoring sites in the SJV that are
equipped with comprehensive particulate matter species
characterization, as well as Bakersfield-Planz, given that it is the
site with the highest annual PM2.5 concentrations in the
base year and projected future year. From the 2016 PM2.5
Plan, the projections are for 2021 (latest permissible Moderate area
attainment year); from the 2018 PM2.5 Plan, the projections
are for 2020 (the analysis year closest to 2021).

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

3. EPA Evaluation and Proposed Action
    The impracticability demonstration in the 2016 PM2.5
Plan is based on air quality modeling that is generally consistent with
applicable EPA guidance. We find the modeling adequate to support the
impracticability demonstration in the plan, as discussed in section
IV.C.3 of this notice. Similarly, the attainment modeling demonstration
in the 2018 PM2.5 Plan is generally consistent with
applicable EPA guidance and provides additional support that it is
impracticable to attain the 2012 PM2.5 NAAQS by 2021.
    We have also evaluated the State's control measure demonstration,
which relies on its BACM/MSM

demonstration, as updated by the 2018 PM2.5 Plan, and find
that it provides for the expeditious implementation of all RACM/RACT
and additional reasonable measures that may feasibly be implemented at
this time, consistent with the requirements of CAA sections 172(c)(1)
and 189(a)(1)(C) for the 2012 PM2.5 NAAQS in the SJV, as
discussed in section IV.D of this notice.
    Finally, we have reviewed available monitored data to assess the
practicability of attaining by 2021. Specifically, the certified 2018-
2020 annual average design value for SJV is 17.6 [micro]g/m\3\ (at
Bakersfield-Planz), with exceedances of the 12.0 [micro]g/m\3\ standard
throughout the area.\155\ We note that the SJV may have experienced
higher than normal PM2.5 concentrations in 2018 and 2020 due
to wildfires in the surrounding areas during the summer and fall
months.\156\ This monitored data similarly supports the State's
demonstration that it is impracticable to attain the 2012
PM2.5 NAAQS by the end of 2021.
---------------------------------------------------------------------------

    \155\ EPA design value workbook dated May 24, 2021,
``pm25_designvalues_2018_2020_final_05_24_21.xlsx,'' worksheets
``Table 1a'' and ``Table 5a.'' The certified design value includes
all available data; no data flagged for exceptional events have been
excluded. The EPA's Air Quality System (AQS) contains ambient air
pollution data collected by federal, state, local, and tribal air
pollution control agencies from thousands of monitors. More
information is available at: https://www.epa.gov/aqs. See also EPA,
2010-2020 AQS Design Value Report, AMP480, June 30, 2021.
    \156\ Concentrations at all 17 monitors in the SJV with data
spanning 2018 to 2020 are significantly higher in 2018 and 2020
relative to concentrations in 2019, possibly due to the wildfires in
those years. 86 FR 38652, 38665, Table 5 (July 22, 2021) (proposed
rule on the 2018 PM2.5 Plan for the 1997 annual
PM2.5 NAAQS of 15.0 [micro]g/m\3\). Notwithstanding the
potential effect of wildfires, ambient PM2.5 levels in
the SJV remain well above the 2012 PM2.5 NAAQS standard
of 12.0 [micro]g/m\3\.
---------------------------------------------------------------------------

    Based on this evaluation, we propose to approve the State's
demonstration in the 2016 PM2.5 Plan that attainment of the
2012 PM2.5 NAAQS in the SJV by the Moderate area attainment
date of December 31, 2021, is impracticable, consistent with the
requirements of CAA section 189(a)(1)(B)(ii). On this basis, we also
propose to reclassify the SJV as a Serious nonattainment area, which
would trigger requirements for the State to submit a Serious area
attainment plan consistent with the requirements of subparts 1 and 4 of
part D, title I of the Act (as described in section V of this notice).

G. Reasonable Further Progress and Quantitative Milestones

1. Requirements for Reasonable Further Progress and Quantitative
Milestones
    Section 172(c)(2) of the CAA states that all nonattainment area
plans shall require RFP. In addition, CAA section 189(c) requires that
all PM2.5 nonattainment area plans include quantitative
milestones that the state must achieve every three years until the area
is redesignated to attainment and that demonstrate RFP. Section 171(1)
defines RFP as ``such annual incremental reductions in emissions of the
relevant air pollutant as are required by [Part D] or may reasonably be
required by the Administrator for the purpose of ensuring attainment of
the applicable [NAAQS] by the applicable date.'' Neither subpart 1 nor
subpart 4 of part D, title I of the Act requires a set percentage of
emission reductions that states must achieve in any given year for
purposes of satisfying the RFP requirement.
    For purposes of the PM2.5 NAAQS, the EPA has interpreted
the RFP requirement to require that nonattainment area plans show
annual incremental emission reductions sufficient to maintain generally
linear progress toward attainment by the applicable deadline.\157\ As
discussed in the EPA's guidance in the General Preamble Addendum,\158\
requiring linear progress in reductions of direct PM2.5 and
any individual precursor in a PM2.5 plan may be appropriate
in the following situations:
---------------------------------------------------------------------------

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

     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 contributes significantly to PM2.5 levels over
the standard), and/or
     the emission reductions necessary to attain the
PM2.5 standard are inventory-wide.\159\
---------------------------------------------------------------------------

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

    The General Preamble Addendum indicates that requiring linear
progress may be less appropriate in other situations, such as in
situations where:
     there are a limited number of sources of direct
PM2.5 or a precursor,
     the relationships between individual sources and air
quality are relatively well defined, and/or
     the emission control systems utilized (e.g., at major
point sources) will result in a swift and dramatic emission reductions.
    In nonattainment areas characterized by any of these latter
conditions, RFP may be better represented as stepwise progress as
controls are implemented and achieve significant reductions soon
thereafter. For example, if an area's nonattainment problem can be
attributed to a few major sources, the EPA's guidance indicates that
``RFP should be met by `adherence to an ambitious compliance schedule'
which is likely to periodically yield significant emission reductions
of direct PM2.5 or a PM2.5 precursor.'' \160\
---------------------------------------------------------------------------

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

    Attainment plans for the PM2.5 NAAQS must include
detailed schedules for compliance with emission regulations in the
nonattainment area and provide corresponding emissions projections for
each applicable milestone year that represent generally linear or
stepwise progress in reducing emissions on an annual basis.\161\ In
reviewing an attainment plan under subpart 4, the EPA considers whether
the annual incremental emission reductions to be achieved are
reasonable in light of the statutory objective of timely attainment.
Although early implementation of the most cost-effective control
measures is often appropriate, states should consider both cost-
effectiveness and pollution reduction effectiveness when developing
implementation schedules for control measures and may implement
measures that are more effective at reducing PM2.5 earlier
to provide greater public health benefits.\162\
---------------------------------------------------------------------------

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

    The PM2.5 SIP Requirements Rule establishes specific
regulatory requirements for purposes of satisfying the Act's RFP
requirements and provides related guidance in the preamble to the rule.
Specifically, under the PM2.5 SIP Requirements Rule, each
PM2.5 attainment plan must contain an RFP analysis that
includes, at a minimum, the following four components: (1) An
implementation schedule for control measures; (2) RFP projected
emissions for direct 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 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.\163\ States should estimate the RFP projected
emissions for each quantitative milestone year by sector on a
pollutant-by-pollutant basis.\164\ In an area that cannot practicably
attain the PM2.5 standard by the applicable Moderate area
attainment date, full implementation of a control strategy that
satisfies the Moderate area control requirements represents RFP towards
attainment.\165\
---------------------------------------------------------------------------

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

    Section 189(c) requires that attainment plans include quantitative
milestones that demonstrate RFP. The purpose of the quantitative
milestones is to allow for periodic evaluation of the area's progress
towards attainment of the NAAQS consistent with RFP requirements.
Because RFP is an annual emission reduction requirement and the
quantitative milestones are to be achieved every three years, when a
state demonstrates compliance with the quantitative milestone
requirement, it will demonstrate that RFP has been achieved during each
of the relevant three years. Quantitative milestones should provide an
objective means to evaluate progress toward attainment meaningfully,
e.g., through imposition of emission controls in the attainment plan
and the requirement to quantify those required emission reductions. The
CAA also requires states to submit milestone reports (due 90 days after
each milestone), and these reports should include calculations and any
assumptions made by the state concerning how RFP has been met, e.g.,
through quantification of emission reductions to date.\166\ The Act
requires states to include RFP and quantitative milestones even for
areas that cannot practicably attain.
---------------------------------------------------------------------------

    \166\ General Preamble Addendum, 42016-42017.
---------------------------------------------------------------------------

    The CAA does not specify the starting point for counting the three-
year periods for quantitative milestones under CAA section 189(c). In
the General Preamble and General Preamble Addendum, the EPA interpreted
the CAA to require that the starting point for the first three-year
period be the due date for the Moderate area plan submission.\167\
Consistent with this longstanding interpretation of the Act, the
PM2.5 SIP Requirements Rule requires that each plan for a
Moderate PM2.5 nonattainment area contain quantitative
milestones to be achieved no later than milestone dates 4.5 years and
7.5 years from the date of designation of the area.\168\ Because the
EPA designated the SJV nonattainment for the 2012 PM2.5
NAAQS effective April 15, 2015,\169\ the applicable quantitative
milestone dates for purposes of this NAAQS in the SJV are October 15,
2019, and October 15, 2022. Following reclassification of the SJV as
Serious for the 2012 PM2.5 standard, later milestones would
be addressed by the Serious area plan.\170\
---------------------------------------------------------------------------

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

2. Summary of State's Reasonable Further Progress Demonstrations and
Quantitative Milestones
a. 2016 PM2.5 Plan RFP and Quantitative Milestones
    The RFP demonstration and quantitative milestones are discussed in
section 3.5 of the 2016 PM2.5 Plan. The plan estimates that
emissions of direct PM2.5 and NOX will generally
decline from the 2013 base year and states that emissions of each of
these pollutants will remain at or below the levels needed to show
``generally linear progress'' through 2022, the Moderate area post-
attainment milestone year for the 2012 PM2.5 NAAQS.\171\ The
Plan's emissions inventory shows that direct PM2.5 and
NOX are emitted by a large number and range of sources in
the SJV and that the emission reductions needed for these pollutants
are inventory-wide.\172\ The Plan states that all RACM and RACT for
stationary, area, and mobile sources have been identified and adopted,
and identifies the District rules achieving emission reductions post-
2013 in Table 3-2 and CARB regulations contributing to attainment in
Table 3-3.
---------------------------------------------------------------------------

    \171\ 2016 PM2.5 Plan, Table 3-6. We note that
Appendix B (``Emissions Inventory'') of the plan indicates that
emissions of ammonia, SOX, and VOC will also generally
decline from the 2013 base year, but the RFP plan does not address
these three precursor pollutants given the State's conclusion that
they do not contribute significantly to PM2.5 levels that
exceed the 2012 PM2.5 NAAQS in the SJV. 2016
PM2.5 Plan, 3-10.
    \172\ 2016 PM2.5 Plan, App. B.
---------------------------------------------------------------------------

    Table 3-6 of the 2016 PM2.5 Plan presents target RFP
emission levels, based on linear emission reductions from 2013 through
2022, and the RFP projected emissions, based on the plan's baseline
emissions inventory and control strategy (i.e., RACM/RACT and
additional reasonable measures) for each quantitative milestone year
(2019 and 2022).\173\ We reproduce Table 3-6, in part, along with the
plan's 2013 base year inventory from Table 3-5, in Table 4. Based on
these analyses, the District and CARB conclude that their adopted
control strategy will achieve sufficient reductions in emissions of
direct PM2.5 and NOX to result in emission levels
at or below the RFP and quantitative milestone target emission levels
for 2019 and 2022.\174\
---------------------------------------------------------------------------

    \173\ Table 3-6 identifies only emission levels for milestone
years that must be addressed by the Moderate area plan (i.e., 2019
and 2022).
    \174\ 2016 PM2.5 Plan, 3-10, and CARB 2016 Staff
Report, 13.

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

    The 2016 PM2.5 Plan documents the State's conclusion
that all RACM/RACT and additional reasonable measures for these
pollutants are being implemented as expeditiously as practicable and
identifies projected levels of direct PM2.5 and
NOX emissions that reflect full implementation of the State,
District, and SJV MPOs' RACM/RACT and additional reasonable measure
control strategy for these pollutants.\175\ The control strategy that
provides the basis for these emission projections is described in
attachments 1 and 2 of the 2016 PM2.5 Plan.
---------------------------------------------------------------------------

    \175\ 2016 PM2.5 Plan, 3-5 through 3-7; see also
evaluation of RACM/RACT and additional reasonable control measures
in section IV.D of this proposed rule.

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

    For quantitative milestones, the 2016 PM2.5 Plan
identifies 2019 and 2022 as the applicable milestone years and includes
milestones to track the State's and District's implementation of
control measures and to document updated emissions data.\176\ For 2019,
the milestone includes a ``list of measures in the SIP control strategy
and key implementation requirements,'' including compliance milestones
in CARB's Truck and Bus Regulation and in the District's Rule 4901 on
residential wood burning. For 2022, the milestone includes a ``list of
measures in the SIP control strategy and key implementation
requirements,'' including compliance milestones in CARB's Truck and Bus
Regulation.
---------------------------------------------------------------------------

    \176\ 2016 PM2.5 Plan, 3-13.
---------------------------------------------------------------------------

b. 2018 PM2.5 Plan RFP and Quantitative Milestones
    Appendix H of the 2018 PM2.5 Plan provides the State's
updated RFP demonstration and quantitative milestones, based on updated
data (e.g., updated emissions inventories, as discussed in section IV.A
of this proposed rule) for the 2019 and 2022 milestone years. Following
the identification of a transcription error in the RFP tables of
Appendix H, the State submitted a revised version of Appendix H that
corrects the transcription error and provides additional information on
the RFP demonstration.\177\ Given the State's conclusions that ammonia,
SOX, and VOC emissions do not contribute significantly to
PM2.5 levels that exceed the 2012 PM2.5 NAAQS in
the SJV, as discussed in section IV.B of this proposed rule, the RFP
demonstration provided by the State addresses emissions of direct
PM2.5 and NOX.\178\ Similarly, the State
developed quantitative milestones based upon the 2018 PM2.5
Plan's strategy for reducing emissions of direct PM2.5 and
NOX.\179\
---------------------------------------------------------------------------

    \177\ Appendix H to 2018 PM2.5 Plan, submitted
February 11, 2020, via the EPA State Planning Electronic
Collaboration System. This revised version of Appendix H replaces
the version submitted with the 2018 PM2.5 Plan on May 10,
2019. All references to Appendix H in this proposed rule are to the
revised version of Appendix H submitted February 11, 2020.
    \178\ 2018 PM2.5 Plan, App. H, H-1.
    \179\ Id. at H-23 to H-24 (for State milestones) and H-20 to H-
21 (for District milestones).
---------------------------------------------------------------------------

    Like the 2016 PM2.5 Plan, the 2018 PM2.5 Plan
estimates that emissions of direct PM2.5 and NOX
will generally decline from the 2013 base year to the 2022 RFP
milestone year and beyond, and that direct PM2.5 and
NOX are emitted by a large number and range of sources in
the SJV. The 2018 PM2.5 Plan relies on the same set of
identified control measures as the 2016 PM2.5 Plan to
demonstrate RFP through 2022, i.e., the baseline measures reflected in
each plan's emissions inventory.\180\
---------------------------------------------------------------------------

    \180\ 2018 PM2.5 Plan, App. H, H-4 to H-15.
---------------------------------------------------------------------------

    In addition to these baseline measures, the 2018 PM2.5
Plan's control strategy includes specific control measure commitments
for purposes of attaining the 2012 PM2.5 NAAQS by 2025,
including commitments by the State and District to develop and propose
to their respective boards specific regulatory and incentive-based
measures identified in the plan by specific years leading up to 2025,
including 2019 and 2022.\181\ Although the attainment demonstration
does not rely on these control measure commitments for emission
reductions until 2024,\182\ the RFP and quantitative milestone elements
of the 2018 PM2.5 Plan rely on these control measure
commitments to demonstrate that the plan requires RFP toward
attainment.\183\
---------------------------------------------------------------------------

    \181\ CARB Resolution 18-49 (October 25, 2018), 5; 2018
PM2.5 Plan, Ch. 4, Table 4-8; email dated November 12,
2019, from Sylvia Vanderspek, CARB to Anita Lee, EPA Region IX,
``RE: SJV PM2.5 information'' (attaching ``Valley State
SIP Strategy Progress''); CARB 2018 Staff Report, 14; SJVUAPCD
Governing Board Resolution 18-11-16 (November 15, 2018), 10-11; 2018
PM2.5 Plan, Ch. 4, tables 4-4 and 4-5; and email dated
November 12, 2019, from Jon Klassen, SJVUAPCD to Wienke Tax, EPA
Region IX, ``RE: follow up on aggregate commitments in SJV
PM2.5 plan'' (attaching ``District Progress In
Implementing Commitments with 2018 PM2.5 Plan'').
    \182\ 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'').
    \183\ 2018 PM2.5 Plan, App. H, H-4 to H-10
(describing commitments by CARB and SJVUAPCD to adopt additional
measures to fulfill tonnage commitments for 2024 and 2025, including
``action'' and ``implementation'' dates occuring before 2024 to
ensure expeditious progress toward attainment).
---------------------------------------------------------------------------

    Specifically, for the 2019 milestone year, Appendix H of the 2018
PM2.5 Plan describes the District's quantitative milestone
as a report on ``[t]he status of SIP measures adopted between 2017 and
2019 as per the schedule included in the adopted Plan, including
Residential Wood Burning Strategy and Commercial Under-Fired
Charbroiler incentive-based strategy.'' \184\ The schedule for
development of new or revised SIP measures is in Chapter 4 of the 2018
PM2.5 Plan and identifies an ``action date'' between 2017
and 2019 for one District measure: ``Rule 4901, Wood Burning Fireplaces
and Wood Burning Heaters (Hot-spot Strategy).'' \185\
---------------------------------------------------------------------------

    \184\ 2018 PM2.5 Plan, App. H, H-20.
    \185\ Id. at Ch. 4, 4-12 (Table 4-4). See also email dated
November 12, 2019, from Jon Klassen, SJVUAPCD to Wienke Tax, EPA
Region IX, ``RE: follow up on aggregate commitments in SJV
PM2.5 plan'' (attaching ``District Progress In
Implementing Commitments with 2018 PM2.5 Plan,'' stating
the District's intent to take action on the listed rules and
measures by beginning the public process on each measure and then
proposing the rule or measure to the SJVUAPCD Governing Board).
---------------------------------------------------------------------------

    Appendix H describes CARB's quantitative milestones as a report on
three measure-specific milestones: (1) Actions taken between 2017 and
2019 to implement the Truck and Bus Regulation that required
particulate filters and cleaner engine standards on existing heavy-duty
diesel trucks and buses in California; (2) implementation of the ``In-
Use Off-Road Diesel-Fueled Fleets Regulation'' (the ``Off-Road
Regulation'') that began in 2014 for large fleets and in 2017 for
medium fleets and limited emissions from existing off-road diesel
vehicles operated in California; and (3) the ``status of SIP measures
adopted between 2017 and 2019, including the California Low-NOX Engine
Standard for new on-road heavy-duty engines used in medium- and heavy-
duty trucks purchased in California.'' \186\ The schedule for
development of new or revised CARB measures is in Chapter 4 of the 2018
PM2.5 Plan and identifies ``action'' dates between 2017 and
2019 for eight CARB measures: ``Lower Opacity Limits for Heavy-Duty
Vehicles,'' ``Amended Warranty Requirements for Heavy-Duty Vehicles,''
the ``Low-NOX Engine Standard,'' ``Innovative Clean
Transit,'' ``Advanced Clean Local Trucks (Last Mile Delivery),''
``Zero-Emission Airport Shuttle Buses,'' ``Zero-Emission Airport Ground
Support Equipment,'' and ``Transport Refrigeration Units Used for Cold
Storage.'' \187\
---------------------------------------------------------------------------

    \186\ Id. at H-23.
    \187\ Id. at 4-28 (Table 4-8). See also email dated November 12,
2019, from Sylvia Vanderspek, CARB to Anita Lee, EPA Region IX,
``RE: SJV PM2.5 information'' (attaching ``Valley State
SIP Strategy Progress'') and CARB 2018 Staff Report, 14-15 (stating
CARB's intent to ``bring to the Board or take action on the list of
proposed State measures for the Valley'' by the action dates
specified in Table 2).
---------------------------------------------------------------------------

    For the 2022 milestone year, Appendix H of the 2018
PM2.5 Plan describes the District's quantitative milestone
as a report on ``[t]he status of SIP measures adopted between 2019 and
2022 as per the schedule included in the adopted Plan, including
Residential Wood Burning Strategy and Commercial Under-Fired
Charbroiler incentive-based strategy.'' \188\ The schedule for
development of new or revised SIP measures in the 2018 PM2.5
Plan identifies ``action dates'' between 2019 and 2022 for 12 District
measures listed in tables 4-4 and 4-5 of Chapter 4, including, for
example, ``Rule 4311, Flares,'' ``Rule 4702, Internal Combustion
Engines,'' and ``Rule 4354,

Glass Melting Furnaces.'' \189\ Appendix H describes CARB's
quantitative milestone as a report on two measure-specific milestones:
(1) Actions taken between 2019 and 2022 to implement the Truck and Bus
Regulation that required particulate filters and cleaner engine
standards on existing heavy-duty diesel trucks and buses in California,
and (2) the ``status of SIP measures adopted between 2019 and 2022,
including Advanced Clean Cars 2 and the Heavy-Duty Vehicle Inspection
and Maintenance Program.'' The schedule for development of new or
revised CARB measures in the 2018 PM2.5 Plan identifies
``action'' dates between 2019 and 2022 for 13 CARB measures listed in
Table 4-8 of Chapter 4, including, for example, the ``Heavy-Duty
Vehicle Inspection and Maintenance Program,'' ``Small Off-Road
Engines,'' and the ``Low-Emission Diesel Fuel Requirement.'' \190\
---------------------------------------------------------------------------

    \188\ 2018 PM2.5 Plan, App. H, H-20.
    \189\ Id. at Ch. 4, 4-12 and 4-13 (tables 4-4 and 4-5). See also
email dated November 12, 2019, from Jon Klassen, SJVUAPCD to Wienke
Tax, EPA Region IX, ``RE: follow up on aggregate commitments in SJV
PM2.5 plan'' (attaching ``District Progress In
Implementing Commitments with 2018 PM2.5 Plan,'' stating
the District's intent to take action on the listed rules and
measures by beginning the public process on each measure and then
proposing the rule or measure to the SJVUAPCD Governing Board).
    \190\ Id. at 4-28 (Table 4-8). See also email dated November 12,
2019, from Sylvia Vanderspek, CARB to Anita Lee, EPA Region IX,
``RE: SJV PM2.5 information'' (attaching ``Valley State
SIP Strategy Progress'') and CARB 2018 Staff Report, 14-15 (stating
CARB's intent to ``bring to the Board or take action on the list of
proposed State measures for the Valley'' by the action dates
specified in Table 2).
---------------------------------------------------------------------------

    Appendix H of the 2018 PM2.5 Plan identifies October 15,
2019, and October 15, 2022, as applicable milestone dates for the 2012
PM2.5 NAAQS.\191\ Table H-11 in Appendix H presents the RFP
projected emissions levels for 2019 and 2022, based on the plan's
emissions inventory and baseline measures. We reproduce Table H-11, in
part, along with the 2018 PM2.5 Plan's base year inventory
for 2013 from Appendix B, in Table 5.
---------------------------------------------------------------------------

    \191\ 2018 PM2.5 Plan, App. H, Table H-12.

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

    The majority of the NOX and PM2.5 reductions
from 2013 to 2019 and 2022 result from CARB's current mobile source
control program, which provides significant ongoing reductions in
emissions of direct PM2.5 and NOX from on-road
and non-road mobile sources, such as light duty vehicles, heavy-duty
trucks and buses, non-road equipment, and fuels. The District has also
adopted numerous stationary and area source rules for direct
PM2.5 and NOX emission sources that are projected
to contribute to RFP towards attainment of the PM2.5
standards. These include control measures for stationary internal
combustion engines, residential fireplaces and woodstoves, glass
manufacturing facilities, agricultural burning sources, and various
sizes of boilers, steam generators, and process heaters used in
industrial operations. CARB's mobile source BACM and MSM analysis in
Appendix D of the 2018 PM2.5 Plan and the District's
stationary and area source BACM and MSM analysis in Appendix C of the
2018 PM2.5 Plan provide a more comprehensive overview of
each of these programs and regulations, among many others.\192\
---------------------------------------------------------------------------

    \192\ 2018 PM2.5 Plan, App. D, Ch. IV, and App. C.
---------------------------------------------------------------------------

3. EPA Evaluation and Proposed Action
a. Reasonable Further Progress
    The EPA has evaluated the RFP demonstrations in the 2016
PM2.5 Plan and 2018 PM2.5 Plan (Appendix H) and
proposes to find that they satisfy the statutory and regulatory
requirements for RFP. Because the RFP demonstration in Appendix H of
the 2018 PM2.5 Plan is based on updated emissions data and
updated information about the control strategies being implemented in
the SJV, we focus our evaluation on Appendix H of the 2018
PM2.5 Plan.
    First, the 2016 PM2.5 Plan and 2018 PM2.5
Plan document the State's, District's, and MPOs' conclusions that they
are implementing all RACM/RACT and additional reasonable measures for
direct PM2.5 and NOX emissions in the SJV as
expeditiously as practicable.\193\ The 2018 PM2.5 Plan also
identifies the State's and District's schedules for developing and
proposing certain new or revised control measures listed in their
respective control measure commitments. These schedules are found in
tables 4-4, 4-5, and 4-8 of the 2018 PM2.5 Plan and in Table
H-2 of Appendix H.
---------------------------------------------------------------------------

    \193\ The RACM/RACT and additional reasonable measures control
strategy that provides the basis for the RFP demonstration is
described in attachments 1 and 2 of the 2016 PM2.5 Plan.
---------------------------------------------------------------------------

    Second, the RFP demonstration contains projected emission levels
for direct PM2.5 and NOX for each applicable
milestone year. These projections are based on continued implementation
of the existing control measures in the area (i.e., baseline measures)
and reflect full implementation of the State, District, and MPOs' RACM/
RACT and additional reasonable measures control strategy for these
pollutants.
    As shown in tables 4 and 5 of this proposed rule, the projected RFP
emission levels in each plan for 2019 and 2022 are equal to the target
RFP emission levels in 2019 and 2022, respectively. We note that the
2013 base year emissions in the 2018 PM2.5 Plan's emissions
inventory are 0.9 tpd lower for both direct PM2.5 and
NOX compared to the base year emissions in the 2016
PM2.5 Plan's emissions inventory, and that the 2018
PM2.5 Plan's projected RFP emission levels for the 2019 and
2022 milestone years represent emission reductions that exceed those of
the 2016 PM2.5 Plan's projected RFP levels by 0.1 tpd direct
PM2.5 and 4.0 tpd NOX in 2019, and by 0.2 tpd
direct PM2.5 and 4.5 tpd NOX in 2022. In other
words, the 2018 PM2.5 Plan's RFP demonstration indicates a
slightly faster pace of emission reductions relative to those in the
2016 PM2.5 Plan's RFP demonstration, and thus represents a
slightly more stringent RFP demonstration than that in the 2016

PM2.5 Plan. These projected emissions levels demonstrate
that the RACM/RACT and additional reasonable measures control strategy
in the 2016 PM2.5 Plan will achieve RFP toward attainment.
    Finally, the RFP demonstration shows that overall pollutant
emissions in each milestone year will be at levels that reflect
generally linear progress toward attainment. The RFP target emissions
levels for 2019 and 2022 identified in both the 2016 PM2.5
Plan and the 2018 PM2.5 Plan reflect consistent progress in
emission reductions from the 2013 base year to the 2022 post-attainment
milestone year for the 2012 PM2.5 NAAQS, based on the
implementation of the RACT/RACT and additional reasonable measures
control strategy.
    For these reasons, we propose to determine that the 2016
PM2.5 Plan, as revised and supplemented by Appendix H of the
2018 PM2.5 Plan, satisfies the requirements for RFP in CAA
section 172(c)(2) and 40 CFR 51.1012 for the 2012 PM2.5
NAAQS in the SJV.
b. Quantitative Milestones
    The 2016 PM2.5 Plan identifies the appropriate years
(2019 and 2022) for quantitative milestones and Appendix H of the 2018
PM2.5 Plan identifies specific quantitative milestone dates
(i.e., October 15, 2019, and October 15, 2022) that are consistent with
the requirements of 40 CFR 51.1013(a)(4). Both plans also identify the
target emission levels for direct PM2.5 and NOX
to be achieved by these milestone dates through implementation of the
control strategy. Finally, Appendix H of the 2018 PM2.5 Plan
identifies commitments by the State and the District to develop and
propose new or revised control measures on a fixed timeframe, for
purposes of attaining the 2012 PM2.5 NAAQS as expeditiously
as practicable. These target emission levels and associated control
requirements, together with the State's and District's commitments to
develop and propose new or revised control measures on a fixed
timeframe, provide for objective evaluation of the area's progress
towards attainment of the 2012 PM2.5 NAAQS.
    The State's quantitative milestones in Appendix H are to implement
specific baseline measures identified in the plan (i.e., the Truck and
Bus Regulation and the Off-Road Regulation) and to develop and propose
several new or revised measures listed in the State's control measure
commitments that apply to heavy-duty trucks and buses and non-road
equipment sources.\194\ These commitments to develop and propose
additional direct PM2.5 and NOX control measures
for mobile sources are part of CARB's strategy for attaining the 2012
PM2.5 NAAQS in the SJV. Similarly, the District's
quantitative milestones in Appendix H are to develop and propose
several new or revised measures listed in the District's control
measure commitments that apply to sources such as residential wood
burning, conservation management practices, glass melting furnaces, and
internal combustion engines. These commitments to develop and propose
additional direct PM2.5 and NOX control measures
for stationary and area sources are part of the District's strategy for
attaining the 2012 PM2.5 NAAQS in the SJV. Thus, the State's
and District's obligations to implement the identified baseline control
measures and to fulfil their respective commitments to develop and
propose new or revised control measures for purposes of attaining the
2012 PM2.5 NAAQS provide objective means for evaluating the
SJV's progress toward timely attainment.
---------------------------------------------------------------------------

    \194\ The EPA is excluding the ``Advanced Clean Cars 2'' measure
from the milestones because this measure is scheduled for
implementation in 2026, well after both the 2022 post-attainment RFP
milestone year and the projected 2025 attainment year for the 2012
PM2.5 NAAQS in the 2018 PM2.5 Plan. Valley
State SIP Strategy, Table 7.
---------------------------------------------------------------------------

    For these reasons, we propose to determine that the 2016
PM2.5 Plan, as revised and supplemented by Appendix H of the
2018 PM2.5 Plan, satisfies the requirements for quantitative
milestones in CAA section 189(c) and 40 CFR 51.1013 for the 2012
PM2.5 NAAQS in the SJV.
    We note that on January 13, 2020, CARB submitted the SJV ``2019
Quantitative Milestone Report for the 2012 PM2.5 NAAQS''
(``2019 QM Report'') to the EPA.\195\ The EPA is currently reviewing
the SJV 2019 QM Report and will determine, as part of its action on the
submitted report, whether the State and District have met their
identified quantitative milestones for 2019.
---------------------------------------------------------------------------

    \195\ Letter dated January 13, 2020, from Richard W. Corey,
Executive Officer, CARB, to Mike Stoker, Regional Administrator, EPA
Region IX, with enclosures.
---------------------------------------------------------------------------

H. Contingency Measures

    We are presenting our review of the SIP submittals for compliance
with contingency measure requirements in two different sections of this
document. In this section, we present our review of the submittals with
respect to the contingency measure requirements for the SJV as a
Moderate area for the 2012 PM2.5 NAAQS for which the state
has submitted an impracticability demonstration. In section VII of this
document, we present our review of the submittals with respect to the
contingency measure requirements for the SJV for the 2006
PM2.5 NAAQS.
1. Requirements for Contingency Measures
    Under CAA section 172(c)(9), states required to make an attainment
plan SIP submission must include contingency measures that they will
implement if the area fails to meet RFP (``RFP contingency measures'')
or fails to attain the NAAQS by the applicable attainment date
(``attainment contingency measures''). Under the PM2.5 SIP
Requirements Rule, states must include contingency measures that will
be implemented following a determination by the EPA that the state has
failed: (1) To meet any RFP requirement in the approved SIP; (2) to
meet any quantitative milestone in the approved SIP; (3) to submit a
required quantitative milestone report; or (4) to attain the applicable
PM2.5 NAAQS by the applicable attainment date.\196\
Contingency measures must be fully adopted rules or control measures
that are ready to be implemented quickly upon failure to meet RFP or
failure of the area to meet the relevant NAAQS by the applicable
attainment date.\197\
---------------------------------------------------------------------------

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

    The EPA does not interpret the requirement for contingency measures
for failing to attain the NAAQS by the applicable attainment date to
apply to a Moderate area that a state adequately demonstrates cannot
practicably attain the NAAQS by the statutory attainment date. Rather,
the EPA believes it is appropriate for the state to identify and adopt
these contingency measures in a timely way as part of the Serious area
attainment plan that it will develop once the EPA reclassifies such an
area. However, if a state with a Moderate area that the EPA has found
cannot practicably attain the NAAQS by the attainment date fails to
meet RFP, when reviewed as part of the quantitative milestone either
4.5 or 7.5 years after designation, then the requirement to implement
contingency measures would be triggered as required by CAA section
172(c)(9).\198\
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    \198\ 81 FR 58010, 58067.
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    The purpose of contingency measures is to continue progress in
reducing emissions while a state revises its SIP to meet the missed RFP
requirement or to correct ongoing nonattainment. Neither the CAA nor
the EPA's implementing regulations establish a specific level of

emission reductions that implementation of contingency measures must
achieve, but the EPA recommends that contingency measures should
provide for emission reductions equivalent to approximately one year of
reductions needed for RFP in the nonattainment area, calculated as the
overall level of reductions needed to demonstrate attainment divided by
the number of years from the base year to the attainment year. In
general, we expect all actions needed to effect full implementation of
the measures to occur within 60 days after the EPA notifies the state
of a failure to meet RFP or to attain.\199\
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    \199\ 81 FR 58010, 58066. See also General Preamble 13512,
13543-13544, and General Preamble Addendum, 42014-42015.
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    To satisfy the requirements of 40 CFR 51.1014, the contingency
measures adopted as part of a PM2.5 attainment plan must
consist of control measures for the area that are not otherwise
required to meet other attainment plan requirements (e.g., to meet
RACM/RACT requirements) and must specify the timeframe within which
their requirements become effective following any of the EPA
determinations specified in 40 CFR 51.1014(a). In a 2016 decision
called Bahr v. EPA (``Bahr''),\200\ the Ninth Circuit Court of Appeals
rejected the EPA's interpretation of CAA section 172(c)(9) to allow
approval of already-implemented control measures as contingency
measures. In Bahr, the Ninth Circuit concluded that contingency
measures must be measures that are triggered and implemented only after
the EPA determines that an area fails to meet RFP requirements or to
attain by the applicable attainment date, and the state must not have
begun to implement such measures before this determination is made.
Thus, already implemented measures cannot serve as contingency measures
under CAA section 172(c)(9). To comply with section 172(c)(9), as
interpreted in the Bahr decision, a state must develop, adopt, and
submit one or more contingency measures to be triggered upon a failure
to meet any RFP requirement, failure to meet a quantitative milestone
requirement, or failure to attain the NAAQS by the applicable
attainment date regardless of the extent to which already-implemented
measures would achieve surplus emission reductions beyond those
necessary to meet RFP or quantitative milestone requirements and beyond
those predicted to achieve attainment of the NAAQS.
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    \200\ Bahr v. EPA, 836 F.3d 1218, 1235-1237 (9th Cir. 2016).
---------------------------------------------------------------------------

2. Summary of State's Contingency Measures
a. 2016 PM2.5 Plan Contingency Measures
    The 2016 PM2.5 Plan includes a contingency measure
element that is intended to address a potential failure to meet RFP
but, consistent with the plan's demonstration that it is impracticable
to attain the 2012 PM2.5 NAAQS by December 31, 2021, that
does not address a potential failure to attain the NAAQS by the
applicable attainment date.\201\ Rather, the State and District
conclude that they intend to identify and adopt contingency measures
for failure to attain as part of the Serious area attainment plan (and,
in fact, have done so in the 2018 PM2.5 Plan). The State and
District use the plan's RFP analysis through 2022 to calculate the
amount of direct PM2.5 and NOX emission
reductions that represents one year's worth of RFP. Specifically, the
State and District divided the difference in emissions in 2022 and 2013
by nine to estimate one year's worth of RFP. The 2016 PM2.5
Plan estimates that one year's worth of RFP is 0.4 tpd of direct
PM2.5 and 14.8 tpd of NOX.\202\ The contingency
measure element does not address ammonia, SOX, and VOC in
light of the State and District's conclusion that each of these three
pollutants does not contribute significantly to exceedances of the 2012
PM2.5 NAAQS in the SJV. In addition, the contingency measure
element in the 2016 PM2.5 Plan only addresses the potential
failure to meet the 2019 RFP milestone, not the potential failure to
meet the 2022 RFP milestone.
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    \201\ 2016 PM2.5 Plan, 3-13 to 3-17.
    \202\ 2016 PM2.5 Plan, Table 3-8.
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    CARB and the District prepared the 2016 PM2.5 Plan prior
to the Bahr decision, and thus did not include any contingency measures
that would only be triggered conditionally and prospectively, upon a
future failure to meet RFP or other relevant event. Instead, CARB and
the District relied only on emissions reductions from already-
implemented measures to satisfy the contingency measure requirement. To
demonstrate sufficient reductions for contingency purposes, the 2016
PM2.5 Plan relies on three types of emission reductions: (1)
0.6 tpd direct PM2.5 and 9.7 tpd NOX emission
reductions that are surplus to those needed by 2019 to meet that year's
linear RFP target emissions, (2) 0.3 tpd NOX emission
reductions from the January 2015 amendment to Rule 4905 (``Natural Gas-
Fired, Fan-Type Central Furnaces'') as being surplus to those captured
in the 2016 PM2.5 Plan's emissions inventory, and (3) 3.0
tpd NOX of incentive-based emission reductions in
conjunction with Rule 9610 (``State Implementation Plan Credit for
Emission Reductions Generated Through Incentive Programs'').\203\
---------------------------------------------------------------------------

    \203\ 2016 PM2.5 Plan, 3-15 and 3-16. See also 2016
PM2.5 Plan, App. C (``SIP Creditable Incentive-Based
Emission Reductions'').
---------------------------------------------------------------------------

    CARB and the District then established a ratio of 1:8.8 to trade
direct PM2.5 emissions for NOX emissions based on
the 2016 PM2.5 Plan's precursor sensitivity analysis for the
traditional high design value sites in Bakersfield.\204\ After
accounting for the 0.4 tpd direct PM2.5 emission reductions
that would meet the 2019 RFP target emission reductions, per the 2019
RFP target emission reductions, the contingency measure element relies
on this trading ratio to convert 0.2 tpd of additional direct
PM2.5 emission reductions in 2019 into 1.8 tpd of
NOX emission reductions equivalent (after rounding to the
tenths place).\205\ Then, after accounting for NOX emission
reductions that would meet the 2019 RFP target emissions reductions,
the contingency measure element sums 9.7 tpd of surplus NOX
emission reductions with 0.3 tpd from the 2015 amendment to Rule 4905,
1.8 tpd from the surplus direct PM2.5 conversion, and 3.0
tpd from the incentive-based emission reductions. The sum of these four
types of reductions equals 14.8 tpd NOX, which matches the
State's estimate of one year's worth of RFP.
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    \204\ 2016 PM2.5 Plan, 3-17.
    \205\ Id. at Table 3-7.
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    Therefore, the 2016 PM2.5 Plan concludes that these
emission reductions (equivalent to one year's worth of progress, i.e.,
0.4 tpd direct PM2.5 and 14.8 tpd NOX) are
sufficient to satisfy the contingency measure requirements for the 2012
PM2.5 NAAQS in the SJV.
b. 2018 PM2.5 Plan Contingency Measures
    The 2018 PM2.5 Plan addresses the contingency measure
requirement for the 2012 PM2.5 NAAQS by reference to the
contingency measure portion of a December 2018 SIP submission that
involved enhanced enforcement of CARB regulations in the SJV, a
commitment to amend the District's residential wood burning rule
(District Rule 4901) to include contingent provisions, and emissions
estimates for the year following the attainment year for use in
evaluating whether the emissions reductions from the

contingency measures are sufficient.\206\ Recently, CARB withdrew the
enhanced enforcement contingency measure of the December 2018 SIP
submission as it pertained to the 2012 PM2.5 NAAQS in the
SJV.\207\ In addition, the 2018 PM2.5 Plan does not include
updated emissions estimates for the years following the 2019 and 2022
RFP milestone years with which to evaluate the sufficiency of
contingency measure intended to address the applicable Moderate area
requirements for the 2012 PM2.5 NAAQS. Rather, with respect
to the 2012 PM2.5 NAAQS, the contingency measure element of
the 2018 PM2.5 Plan only includes estimates for the year
(2026) following the Serious area attainment year (2025), and thus,
these estimates are not relevant for evaluating the sufficiency of
contingency measures submitted to comply with the Moderate area
requirements for the 2012 PM2.5 NAAQS.
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    \206\ 2018 PM2.5 Plan, App. H (revised February 11,
2020), H-24 to H-26.
    \207\ Letter dated March 19, 2021, from Richard W. Corey,
Executive Officer, CARB, to Deborah Jordan, Acting Regional
Administrator, EPA Region IX, with enclosures.
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    Accordingly, we have evaluated the relevant portions of the 2018
PM2.5 Plan and District Rule 4901 (specifically, section
5.7.3 of Rule 4901), and the contingency measure element in the 2016
PM2.5 Plan as discussed above, for compliance with the
applicable requirements for Moderate areas for the 2012
PM2.5 NAAQS. However, while the 2018 PM2.5 Plan
does not provide updated emissions estimates for the years following
the 2019 and 2022 RFP milestone years, the updated emission estimates
in the 2018 PM2.5 Plan do provide the basis for an updated
estimate of one year's worth of RFP for the purposes of evaluating the
sufficiency of contingency measures to meet the applicable Moderate
area requirements for the 2012 PM2.5 NAAQS. The updated
estimates of emissions one year's worth of RFP based on the updated
emissions estimates in the 2018 PM2.5 Plan are 0.5 tpd
direct PM2.5 and 15.3 tpd NOX.\208\ This is
slightly more reductions than the 0.4 tpd direct PM2.5 and
14.8 tpd NOX emission reductions estimated as one year's RFP
within the 2016 PM2.5 Plan, consistent with the slightly
faster pace of emission reductions reflected in the 2018
PM2.5 Plan and discussed in section IV.G.3 of this proposed
rule.
---------------------------------------------------------------------------

    \208\ The estimate of one year's RFP is based on difference
between the annual average base year (2013) emissions and the
corresponding emissions in the 2022 RFP milestone year, per Appendix
B of the 2018 PM2.5 Plan, divided by nine (i.e., the
number of years between 2013 and 2022).
---------------------------------------------------------------------------

    With respect to the District contingency measure, the 2018
PM2.5 Plan calls for the District to amend District Rule
4901 (Wood Burning Fireplaces and Wood Burning Heaters) to include a
requirement in the rule with a trigger that would be activated should
the EPA issue a final rulemaking that the SJV failed to meet a
regulatory requirement necessitating implementation of a contingency
measure. In response to the commitment made in the 2018
PM2.5 Plan, in June 2019, the District adopted amendments to
Rule 4901 including a contingency measure (in section 5.7.3 of the
amended rule), and, as an attachment to a letter dated July 19, 2019,
CARB submitted the amended rule to the EPA for approval.\209\ The EPA
has taken final action to approve amended Rule 4901, but in that
approval, we noted that we were not evaluating the contingency measure
in section 5.7.3 of revised Rule 4901 for compliance with all
requirements of the CAA and the EPA's implementing regulations that
apply to such measures.\210\ Rather, we approved the measure into the
SIP because it strengthened the rule by providing a possibility of
additional curtailment days, and thus potentially additional emissions
reductions. We indicated that we would evaluate whether this provision,
in conjunction with other submitted provisions, meets the statutory and
regulatory requirements for contingency measures in future actions. In
this proposal, we are now evaluating District Rule 4901, specifically,
section 5.7.3, for compliance with the requirements for contingency
measures for Moderate areas that cannot practicably attain the 2012
PM2.5 NAAQS by the applicable Moderate area attainment date.
---------------------------------------------------------------------------

    \209\ Letter from Richard W. Corey, Executive Officer, CARB, to
Mike Stoker, Regional Administrator, EPA Region IX, July 19, 2019.
    \210\ 85 FR 44206 (July 22, 2020) (final approval of District
Rule 4901); 85 FR 1131, 1132-33 (January 9, 2020) (proposed approval
of District Rule 4901).
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    District Rule 4901 is designed to limit emissions generated by the
use of wood burning fireplaces, wood burning heaters, and outdoor wood
burning devices. The rule establishes requirements for the sale/
transfer, operation, and installation of wood burning devices and for
advertising the sale of seasoned wood consistent with a moisture
content limit within the SJV.
    The rule includes a two-tiered, episodic wood burning curtailment
requirement that applies during four winter months, November through
February. During a level one episodic wood burning curtailment, section
5.7.1 prohibits any person from operating a wood burning fireplace or
unregistered wood burning heater but permits the use of a properly
operated wood burning heater that meets certification requirements and
has a current registration with the District. Sections 5.9 through 5.11
impose specific registration requirements on any person operating a
wood burning fireplace or wood burning heater and section 5.12 imposes
specific certification requirements on wood burning heater
professionals. During a level two episodic wood burning curtailment,
operation of any wood burning device is prohibited by section 5.7.2.
    Prior to the 2019-2020 wood burning season, the District imposed a
level one curtailment when the PM2.5 concentration was
forecasted to be between 20-65 [micro]g/m\3\ and imposed a level two
curtailment when the PM2.5 concentration was forecasted to
be above 65 [micro]g/m\3\ or the PM10 concentration was
forecasted to be above 135 [micro]g/m\3\. In 2019 the District adopted
revisions to Rule 4901 to lower the wood burning curtailment thresholds
in the ``hot spot'' counties of Madera, Fresno, and Kern. The District
lowered the level one PM2.5 threshold for these three
counties from 20 [micro]g/m\3\ to 12 [micro]g/m\3\, and the level two
PM2.5 threshold from 65 [micro]g/m\3\ to 35 [micro]g/m\3\.
The District did not modify the curtailment thresholds for other
counties (i.e., Kings, Merced, San Joaquin, Stanislaus, and Tulare
counties) in the SJV, and those levels remained at 20 [micro]g/m\3\ for
level one and 65 [micro]g/m\3\ for level two.
    The District's 2019 revision to Rule 4901 also included the
addition of a contingency measure in section 5.7.3 of the rule,
requiring that 60 days following the effective date of an EPA final
rulemaking that the SJV has failed to attain the 1997, 2006, or 2012
PM2.5 NAAQS by the applicable attainment date, the
PM2.5 curtailment levels for any county that has failed to
attain the applicable standard will be lowered to the curtailment
levels in place for hot spot counties.
3. EPA Evaluation and Proposed Action
    We have evaluated the contingency measure element in the 2016
PM2.5 Plan, as amended in the 2018 PM2.5 Plan,
and we find that the fact that the element focuses only on direct
PM2.5 and NOX (and not ammonia, SO2,
and VOC) is acceptable in light of our proposed approval of the
precursor demonstration in section IV.B of this document.
    PM2.5 attainment plan SIP submission for Moderate areas
that cannot practicably attain by the Moderate area attainment date
must include

contingency measures for potential failures to meet RFP, submit a
quantitative milestone report or meet the quantitative milestones
associated with the period 4.5 and 7.5 years after designation (in this
case, the 2019 and 2022 RFP milestone years). With respect to both RFP
milestone years, we find that the contingency measure element is
inadequate to meet the Moderate area contingency measure requirements
for several reasons.
    First, the emission reductions relied upon in the contingency
measure element to show compliance with the contingency measure
requirement (i.e., those surplus to RFP, reductions from the 2015
amendments to Rule 4905, and incentive-based emission reductions from
projects in 2011-2016 in conjunction with District Rule 9610) come from
measures that are not prospective (i.e., to-be-triggered) but rather
come from measures that have already been implemented, and thus would
not constitute contingency measures under CAA section 172(c)(9)
consistent with the Bahr decision.\211\
---------------------------------------------------------------------------

    \211\ We note that the Ninth Circuit's decision in Bahr v. EPA
was published on September 12, 2016, just three days before the
SJVUAPCD adopted the 2016 PM2.5 Plan on September 15,
2016. Subsequently, the District and CARB addressed the Bahr
decision within their discussion of contingency measures for the
Serious area plan for the 2012 PM2.5 NAAQS in the San
Joaquin Valley (i.e., the 2018 PM2.5 Plan).
---------------------------------------------------------------------------

    We recognize that the District has taken action to fulfill the
commitment in the 2018 PM2.5 Plan to revise District Rule
4901 to include specific to-be-triggered contingency provisions.
However, the contingency measure provision (section 5.7.3) added to the
rule is only triggered by a finding of failure to attain the
PM2.5 NAAQS by the applicable attainment date and not by
failures to meet a quantitative milestone, submit a quantitative
milestone report, or failure to meet an RFP requirement. Thus, the rule
does not include contingency provisions to address the types of
failures that are the triggering events for contingency measures for
Moderate areas that cannot practicably attain the PM2.5
NAAQS by the applicable attainment date. Therefore, section 5.7.3 of
District Rule 4901 does not meet the contingency measure requirements
of CAA section 172(c)(9) and 40 CFR 51.1014 for the SJV with respect to
Moderate area requirements for the 2012 PM2.5 NAAQS.
    Second, as a general matter, we find that surplus emissions
reductions in the years following RFP milestone years can be taken into
account in determining whether a contingency measure or contingency
measures are adequate for a given area for a given pollutant
notwithstanding the fact that the contingency measure or contingency
measures would not achieve reductions equivalent to one year's worth of
RFP. However, the contingency measure element in the 2016
PM2.5 Plan provides no emissions estimates for the year
following the 2022 RFP milestone year for such an evaluation. The
contingency measure element of the nonattainment area plan only
provides estimates of surplus emissions reductions in 2019.
    Furthermore, with respect to the emissions analysis for 2019,
neither Rule 9610 (``State Implementation Plan Credit for Emission
Reductions Generated Through Incentive Programs'') nor the list of Carl
Moyer incentive projects in Appendix C of the 2016 PM2.5
Plan may be relied upon as a source for surplus emissions reductions
because Rule 9610 is not an emission reduction measure \212\ and
because the Carl Moyer incentive projects listed in Appendix C of the
2016 PM2.5 Plan do not satisfy CAA requirements for SIP
emission reduction credit, as interpreted in the EPA's guidance.\213\
In addition, the emission reductions that might otherwise be considered
surplus due to the 2015 adoption of tighter emissions limits in
District Rule 4905 would not be considered surplus without additional
documentation because of the option in Rule 4905 to pay mitigation fees
in lieu of compliance with emissions limits.\214\
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    \212\ 80 FR 19020 (April 9, 2015) (final approval of Rule 9610),
79 FR 28652 (May 19, 2014) (proposed approval noting that ``[Rule
9610] does not establish any emission limitation, control measure,
or other requirement that applies directly to an emission source''),
and EPA, Region IX Air Division, ``Technical Support Document for
EPA's Notice of Proposed Rulemaking for the California State
Implementation Plan, San Joaquin Valley Unified Air Pollution
Control District's Rule 9610, State Implementation Plan Credit for
Emission Reductions Generated through Incentive Programs,'' May
2014, 4-5 (noting that Rule 9610 ``does not apply to any emission
source and does not directly impact emissions'').
    \213\ The EPA's longstanding position with respect to incentive-
based control measures is that SIP credit may be allowed for such
measures only where the State submits enforceable mechanisms to
ensure that the emission reductions necessary to meet applicable CAA
requirements are achieved--e.g., an enforceable commitment to
monitor and report on emission reductions achieved and to rectify
any shortfall in a timely manner. See, e.g., 80 FR 19020, 19026. The
2016 PM2.5 Plan does not contain such enforceable
mechanisms addressing the Carl Moyer projects listed in Appendix C.
    \214\ EPA, Region IX Air Division, ``Technical Support Document
for EPA's Proposed Rulemaking for the California State
Implementation Plan (SIP), San Joaquin Valley Unified Air Pollution
Control District's Rule 4905, Natural Gas-Fired, Fan-Type Central
Furnaces,'' October 5, 2015, fn. 8. The EPA approved the 2015
amended version of District Rule 4905 at 81 FR 17390 (March 29,
2016).
---------------------------------------------------------------------------

    Third, as a general matter, we agree that the use of trading ratios
established through modeling techniques to convert surplus reductions
of direct PM2.5 emissions to equivalent PM2.5
precursor emissions may be appropriate as part of the explanation for
why a given contingency measure or measures are sufficient in an area
with respect to a specific NAAQS. In this instance, however, we note
that reliance on trading surplus direct PM2.5 reductions for
NOX reductions at a ratio of 1:8.8 may overestimate the
amount of equivalent NOX reductions based on the information
in the 2018 PM2.5 Plan. For the 2018 PM2.5 Plan,
the State conducted further analysis of the sensitivity of ambient
PM2.5 to emission reductions in PM2.5 precursors,
as discussed in section IV.I.2 of this proposal. Based on this updated
analysis for Bakersfield and Fresno sites, the State proposes to use a
1:6.5 trading ratio between direct PM2.5 and NOX
for purposes of the 2018 PM2.5 Plan's MVEBs. This suggests
that, while for a different CAA purpose (i.e., MVEB rather than
contingency measures), any excess direct PM2.5 used for
evaluation of contingency measures would be equivalent to fewer
NOX emissions reductions than assumed for the 2016
PM2.5 Plan.
    Therefore, in light of the deficiencies described in the preceding
paragraphs, we are proposing to disapprove the contingency measure
element of the 2016 PM2.5 Plan, as amended in the 2018
PM2.5 Plan, for failure to meet the requirements for
contingency measures under CAA section 172(c)(9) and 40 CFR 51.1014(a)
in the SJV with respect to Moderate area requirements for the 2012
PM2.5 NAAQS. More specifically, we are proposing to
disapprove the contingency measure element for failure to provide for
the implementation of specific measures to be undertaken if the area
fails, with respect to the 2019 and 2022 RFP milestone years, to meet
RFP, to submit a quantitative milestone report (2022 RFP milestone year
only),\215\ or to meet the quantitative milestones and that, once
triggered, provide sufficient emissions reductions to meet the purposes
of contingency measures under the CAA and EPA's implementing
regulations.
---------------------------------------------------------------------------

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

I. Motor Vehicle Emissions Budgets

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

maintenance areas to conform to the SIP's goals of eliminating or
reducing the severity and number of violations of the NAAQS and
achieving timely attainment of the standards. Conformity to the SIP's
goals means that such actions will not: (1) Cause or contribute to
violations of a NAAQS, (2) worsen the severity of an existing
violation, or (3) delay timely attainment of any NAAQS or any interim
milestone.
    Actions involving Federal Highway Administration (FHWA) or Federal
Transit Administration (FTA) funding or approval are subject to the
EPA's transportation conformity rule, codified at 40 CFR part 93,
subpart A. Under this rule, MPOs in nonattainment and maintenance areas
coordinate with state and local air quality and transportation
agencies, the EPA, the FHWA, and the FTA to demonstrate that an area's
regional transportation plans and transportation improvement programs
conform to the applicable SIP. This demonstration is typically done by
showing that estimated emissions from existing and planned highway and
transit systems are less than or equal to the MVEBs contained in all
control strategy SIPs. An attainment, maintenance, or RFP SIP should
include budgets for the attainment year, each required RFP milestone
year, and the last year of the maintenance plan, as appropriate.
Budgets are generally established for specific years and specific
pollutants or precursors and must reflect all of the motor vehicle
control measures contained in the attainment and RFP
demonstrations.\216\
---------------------------------------------------------------------------

    \216\ 40 CFR 93.118(e)(4)(v).
---------------------------------------------------------------------------

    Under the PM2.5 SIP Requirements Rule, each attainment
plan submittal for a Moderate PM2.5 nonattainment area must
contain quantitative milestones to be achieved no later than 4.5 years
and 7.5 years after the date the area was designated
nonattainment.\217\ The second of these milestone dates, October 15,
2022,\218\ falls after the latest permissible Moderate area attainment
date for the SJV, which is December 31, 2021. As the EPA explained in
the preamble to the PM2.5 SIP Requirements Rule, it is
important to include a post-attainment year quantitative milestone to
ensure that, if the area fails to attain by the attainment date, the
EPA can continue to monitor the area's progress toward attainment while
the state develops a new attainment plan.\219\ Moderate area plans
demonstrating that attainment by the Moderate area attainment date is
impracticable must, therefore, include budgets for both of the
milestone dates. States that submit impracticability demonstrations for
Moderate areas under CAA section 189(a)(1)(B)(ii), however, are not
required to submit budgets for the attainment year because the
submitted SIP does not demonstrate attainment.\220\
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    \217\ 40 CFR 51.1013(a)(1).
    \218\ Because the SJV was designated nonattainment effective
April 15, 2015, the first milestone date is October 15, 2019, and
the second milestone date is October 15, 2022. 80 FR 2206.
    \219\ 81 FR 58010, 58058 and 58063-58064.
    \220\ Id. at 58055.
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    PM2.5 plans should identify budgets for direct
PM2.5, NOX, and all other PM2.5
precursors for which on-road emissions are determined to contribute
significantly to PM2.5 levels in the area for each RFP
milestone year and the attainment year, if the plan demonstrates
attainment. All direct PM2.5 SIP budgets should include
direct PM2.5 motor vehicle emissions from tailpipes, brake
wear, and tire wear. With respect to PM2.5 from re-entrained
road dust and emissions of VOC, SO2, and/or ammonia, the
transportation conformity provisions of 40 CFR part 93, subpart A,
apply only if the EPA Regional Administrator or the director of the
state air agency has made a finding that transportation-related
emissions of these pollutants within the area are a significant
contributor to the PM2.5 nonattainment problem and has so
notified the MPO and Department of Transportation (DOT), or if the
applicable implementation plan (or implementation plan submission)
includes any of these pollutants in the approved (or adequate) budget
as part of the RFP, attainment, or maintenance strategy.\221\
Additionally, as the EPA explained in its May 6, 2005 transportation
conformity rule amendments for the PM2.5 NAAQS, it is not
necessary for a SIP to explicitly state that VOC, SO2, and/
or ammonia are insignificant precursors. Instead, states should
consider the on-road contribution of all four precursors to the
PM2.5 problem as they develop their SIPs and establish
emissions budgets for those precursors for which on-road emissions need
to be addressed in order to attain the PM2.5 standard as
expeditiously as practicable. Conformity determinations must address
all precursors for which the SIP establishes a budget and need not
address those precursors for which the state has not established a
budget because the emissions of that precursor are insignificant.\222\
---------------------------------------------------------------------------

    \221\ 40 CFR 93.102(b)(3), 93.102(b)(2)(v), and 93.122(f); see
also transportation conformity rule preambles at 69 FR 40004, 40031-
40036 (July 1, 2004), 70 FR 24280, 24283-24285 (May 6, 2005) and 70
FR 31354 (June 1, 2005).
    \222\ 70 FR 24280, 24287 (May 6, 2005).
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    By contrast, transportation conformity requirements apply with
respect to emissions of NOX unless both the EPA Regional
Administrator and the director of the state air agency have made a
finding that transportation-related emissions of NOX within
the nonattainment area are not a significant contributor to the
PM2.5 nonattainment problem and have so notified the MPO and
DOT, or the applicable implementation plan (or implementation plan
submission) does not establish an approved (or adequate) budget for
such emissions as part of the RFP, attainment, or maintenance
strategy.\223\
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    \223\ 40 CFR 93.102(b)(2)(iv).
---------------------------------------------------------------------------

    The criteria for insignificance determinations are provided in 40
CFR 93.109(f). In order for a pollutant or precursor to be considered
an insignificant contributor, the control strategy SIP must demonstrate
that it would be unreasonable to expect that such an area would
experience enough motor vehicle emissions growth in that pollutant/
precursor for a NAAQS violation to occur. Insignificance determinations
are based on factors such as air quality, SIP motor vehicle control
measures, trends and projections of motor vehicle emissions, and the
percentage of the total SIP inventory that is comprised of motor
vehicle emissions. The EPA's rationale for providing for insignificance
determinations is described in the July 1, 2004, revision to the
transportation conformity rule.\224\
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    \224\ 69 FR 40004.
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    The EPA's process for determining the adequacy of a budget consists
of three basic steps: (1) Notifying the public of a SIP submittal; (2)
providing the public the opportunity to comment on the budget during a
public comment period; and (3) making a finding of adequacy or
inadequacy. The EPA can notify the public by either posting an
announcement that the EPA has received SIP budgets on the EPA's
adequacy website (40 CFR 93.118(f)(1)), or through a Federal Register
notice of proposed rulemaking when the EPA reviews the adequacy of an
implementation plan budget simultaneously with its review and action on
the SIP itself (40 CFR 93.118(f)(2)).
    For budgets to be approvable, they must meet, at a minimum, the
EPA's adequacy criteria (40 CFR 93.118(e)(4)). To meet these
requirements, the budgets must be consistent with the attainment and
RFP requirements and reflect all of the motor vehicle control measures

contained in the attainment and RFP demonstrations.\225\
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    \225\ 40 CFR 93.118(e)(4)(iii), (iv) and (v). For more
information on the transportation conformity requirements and
applicable policies on MVEBs, please visit our transportation
conformity website at: http://www.epa.gov/otaq/stateresources/transconf/index.htm.
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2. Summary of State's Motor Vehicle Emissions Budgets
    The 2016 PM2.5 Plan includes budgets for direct
PM2.5 and NOX for 2019 (RFP milestone year) and
2022 (post-attainment RFP milestone year) and no other year given the
plan's demonstration of the impracticability of attaining the 2012
PM2.5 NAAQS by 2021.\226\ Similarly, for the Moderate area
timeframe, the 2018 PM2.5 Plan includes budgets for direct
PM2.5 and NOX for 2019 and 2022 RFP milestone
years.\227\ We consider the 2019 and 2022 RFP milestone budgets from
the 2018 PM2.5 Plan as superseding the corresponding budgets
from the 2016 PM2.5 Plan.
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    \226\ 2016 PM2.5 Plan, Table 3-11.
    \227\ 2018 PM2.5 Plan, App. D, Table 3-3.
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    The budgets in both the 2016 PM2.5 Plan and the 2018
PM2.5 Plan were calculated using EMFAC2014 and the latest
modeled vehicle activity data (vehicle miles traveled and speed
distributions) available at the time of plan development. In the case
of the 2016 PM2.5 Plan, vehicle activity data are derived
from the draft 2017 Federal-Statewide Transportation Improvement
Program (2017 FSTIP) from each of the SJV's eight MPOs. The 2018
PM2.5 Plan budgets are based on updated motor vehicle
activity data from the most recently amended 2017 FSTIP (as of January
2018) from each of the SJV's eight MPOs. The budgets reflect annual
average emissions consistent with the annual averaging period of the
2012 PM2.5 NAAQS and the 2018 PM2.5 Plan's RFP
demonstration.
    As with the 2016 PM2.5 Plan, the 2018 PM2.5
Plan includes direct PM2.5 budgets for tailpipe, brake wear,
and tire wear emissions, but does not include paved road dust, unpaved
road dust, and road construction dust emissions. The 2018
PM2.5 Plan also includes budgets for NOX, as a
regulated precursor under the plan, but does not include budgets for
VOC, SO2, or ammonia.\228\ The budgets included in the 2018
PM2.5 Plan with respect to the Moderate area timeframe are
shown in Table 6.
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    \228\ 2018 PM2.5 Plan, App. D, D-121 to D-123.

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

    The 2018 PM2.5 Plan also includes a proposed trading
mechanism for transportation conformity analyses that would allow
future decreases in NOX emissions from on-road mobile
sources to offset any on-road increases in direct PM2.5
emissions. For the 2012 PM2.5 NAAQS, the State is proposing
to use the 6.5:1 NOX:PM2.5 ratio. The ratio is
based on a sensitivity analysis based on a 30% reduction of
NOX or PM2.5 emissions and the corresponding
impact on design values at sites in Bakersfield and Fresno (i.e.,
updated analysis relative to the 2008 PM2.5 Plan for the
1997 PM2.5 NAAQS). For the sake of comparison, in approving
the budgets for the SJV 2008 PM2.5 Plan for the 1997
PM2.5 NAAQS, the EPA approved a trading mechanism for
transportation conformity analyses that allowed for such one-way trades
(i.e., only excess NOX can be used to offset
PM2.5, not vice versa) at a 9:1
NOX:PM2.5 ratio.\229\
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    \229\ 76 FR 69896, at 69923 (November 9, 2011).
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    To ensure that the trading mechanism does not affect the ability of
the SJV to meet the NOX budget, the NOX emission
reductions available to supplement the PM2.5 budget would
only be those remaining after the NOX budget has been
met.\230\ The Plan also provides that the SJV MPOs shall clearly
document the calculations used in the trading, along with any
additional reductions of NOX and PM2.5 emissions
in the conformity analysis.
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    \230\ 2018 PM2.5 Plan, App. D, D-126 and D-127.
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    In the submittal letter for the 2018 PM2.5 Plan, CARB
requested that we limit the duration of our approval of the budgets to
the period before the effective date of the EPA's adequacy finding for
any subsequently submitted budgets.\231\
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    \231\ Letter dated May 9, 2019, from Richard W. Corey, Executive
Officer, CARB, to Mike Stoker, Regional Administrator, EPA Region
IX, 3.
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3. EPA Evaluation and Proposed Action
    For the reasons discussed in section IV.F of this proposed rule, we
are proposing to approve the State's demonstration that it is
impracticable to attain the 2012 PM2.5 standard in the SJV
by the applicable Moderate area attainment date of December 31, 2021,
and are proposing to reclassify the area as Serious. Accordingly, we
are proposing action on the Moderate post-attainment year budgets for
2022 for the 2012 PM2.5 NAAQS in the SJV. The EPA is not
reviewing the submitted motor vehicle emissions budgets for 2019
because that year will not be an applicable conformity analysis year in
the next conformity analysis for the SJV MPOs. Also, as noted above, we
consider the 2022 RFP milestone budgets from the 2018 PM2.5
Plan as superseding the corresponding budgets from the 2016
PM2.5 Plan and thus are proposing action only on the
former.\232\
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    \232\ The differences between the two sets of budgets are minor.
For 2019, there is no difference between the budgets in the 2016
PM2.5 Plan and the 2018 PM2.5 Plan. For 2022,
there is no difference between the two sets of budgets for direct
PM2.5, and, with the exception of San Joaquin County, the
difference between the two sets of budgets for NOX is
less than or equal to 0.1 tpd. For San Joaquin County, the 2022
NOX budget is 0.7 tpd higher under the 2018
PM2.5 Plan than the corresponding budget from the 2016
PM2.5 Plan.
---------------------------------------------------------------------------

    The EPA generally first conducts a preliminary review of budgets
submitted with an attainment or maintenance plan for PM2.5
for

adequacy, prior to taking action on the plan itself, and did so with
respect to the PM2.5 budgets in the 2018 PM2.5
Plan. On June 18, 2019, the EPA announced the availability of the 2018
PM2.5 Plan with MVEBs and a 30-day public comment period.
This announcement was posted on the EPA's adequacy website at: https://www.epa.gov/state-and-local-transportation/state-implementation-plans-sip-submissions-currently-under-epa. The comment period for this
notification ended on July 18, 2019. We did not receive any comments
during this comment period.
    The 2018 PM2.5 Plan establishes budgets for the 2022 RFP
milestone year for direct PM2.5 and NOX, but not
for the other PM2.5 precursor emissions (i.e., VOC,
SO2, and ammonia). We propose to find that it is not
necessary to establish motor vehicle emissions budgets for
transportation-related emissions of VOC, SO2, and ammonia to
attain the 2012 annual PM2.5 NAAQS in the SJV based on our
proposal to approve the State's demonstration that emissions of VOC,
SO2, and ammonia do not contribute significantly to
PM2.5 levels that exceed the 2012 PM2.5 NAAQS in
the SJV, as discussed in section IV.B of this proposed rule. Our
finding in this regard is also supported by information about VOC,
SO2, and ammonia in the 2018 PM2.5 Plan
documenting the small contribution by motor vehicles to regional
precursor inventories and to PM2.5 design values within the
SJV.\233\ In addition, based on similar documentation about re-
entrained road dust and construction-related fugitive dust in the 2018
PM2.5 Plan and in accordance with 40 CFR 93.102(b)(3) and
93.122(f), the EPA proposes to find that it is not necessary to include
re-entrained road dust emissions or road construction dust in the
direct PM2.5 budgets for 2012 PM2.5 NAAQS in the
SJV.\234\
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    \233\ 2018 PM2.5 Plan, App. D. pages D-121, D-122 and
D-123. Motor vehicle emissions of VOC represent approximately 10% of
the total VOC emissions in the SJV, but VOC controls are generally
ineffective at reducing ambient PM2.5 levels. Motor
vehicle emissions of SO2 are less than one tpd, and motor
vehicle emissions of ammonia represent approximately 1% of total
ammonia emissions in the SJV.
    \234\ Id. Paved and unpaved road dust emissions represent less
than 17% of the total PM2.5 emissions in the SJV but
contribute only approximately 4% to the design values. Construction
dust emissions are less than 5% of the total PM2.5
emissions in the SJV. In addition, the 2018 PM2.5 Plan
does not include additional control measures for these sources.
---------------------------------------------------------------------------

    For the reasons discussed in sections IV.G of this proposed rule,
the EPA proposes to approve the RFP demonstration in the 2018
PM2.5 Plan. The 2022 RFP budgets, as shown in Table 6 of
this proposed rule, are consistent with this demonstration, are clearly
identified and precisely quantified, and meet all other applicable
statutory and regulatory requirements including the adequacy criteria
in 40 CFR 93.118(e)(4) and (5). For these reasons, the EPA proposes to
approve the budgets listed in Table 6. We provide a more detailed
discussion in the EPA's memo to file regarding MVEB.\235\ We are not
proposing to approve the 2018 PM2.5 Plan's budgets that
pertain solely to the Serious area time frame (i.e., 2025 attainment
year budget or the post-attainment year 2028 budget for the 2012
PM2.5 NAAQS) at this time. The budgets that the EPA is
proposing to approve relate to the 2012 annual PM2.5 NAAQS
only, and our proposed approval does not affect the status of the
previously-approved MVEBs for the 1997 annual and 24-hour
PM2.5 NAAQS and 2006 24-hour PM2.5 NAAQS and
related trading mechanisms that remain in effect for that
PM2.5 NAAQS.
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    \235\ Memorandum of July 30, 2021, from Rory Mays and Karina
O'Connor, Air Planning Office, Air and Radiation Division, Region
IX, EPA, ``EPA Review of 2018 PM2.5 Plan Transportation
Conformity Emission Budgets for the 2012 Annual PM2.5
NAAQS (Moderate Area Requirements).''
---------------------------------------------------------------------------

    As noted above, the State included a trading mechanism to be used
in transportation conformity analyses that would be used in conjunction
with the budgets in the 2018 PM2.5 Plan, as allowed for
under 40 CFR 93.124(b). Furthermore, the trading ratio in the 2018
PM2.5 Plan is based on updated air quality modeling and
analysis relative to the analysis that the 2016 PM2.5 Plan
relies on (i.e., analysis and trading ratio in the 2008
PM2.5 Plan for the 1997 PM2.5 NAAQS). The trading
mechanism in the 2018 PM2.5 Plan would allow future
decreases in annual NOX emissions from on-road mobile
sources to offset any on-road increases in annual direct
PM2.5 emissions using a 6.5:1
NOX:PM2.5 ratio for conformity for the 2012
annual PM2.5 NAAQS. To ensure that the trading mechanism
does not affect the ability to meet the NOX budget, the plan
provides that the NOX emission reductions available to
supplement the PM2.5 budget would only be those remaining
after the NOX budget has been met. The SJV MPOs will have to
document clearly the calculations used in the trading when
demonstrating conformity, along with any additional reductions of
NOX and PM2.5 emissions in the conformity
analysis. The trading calculations must be performed prior to the final
rounding to demonstrate conformity with the budgets.
    The EPA has reviewed the trading mechanism as described on pages D-
125 through D-127 in Appendix D of the 2018 PM2.5 Plan and
finds it is appropriate for transportation conformity purposes in the
SJV for the 2012 annual PM2.5 NAAQS. The methodology for
estimating the trading ratio for conformity purposes is essentially an
update (based on newer modeling) of the approach that the EPA
previously approved for the 2008 PM2.5 Plan for the 1997
PM2.5 NAAQS \236\ and the 2012 PM2.5 Plan for the
2006 24-hour PM2.5 NAAQS.\237\ The State's approach in the
previous plans was to model the ambient PM2.5 effect of
areawide NOX emissions reductions and of areawide direct
PM2.5 reductions, and to express the ratio of these modeled
sensitivities as an interpollutant trading ratio.
---------------------------------------------------------------------------

    \236\ 80 FR 1816, 1841 (January 13, 2015) (noting the EPA's
prior approval of MVEBs for the 1997 annual and 24-hour
PM2.5 standards in the 2008 PM2.5 Plan at 76
FR 69896).
    \237\ 81 FR 59876 (August 31, 2016).
---------------------------------------------------------------------------

    In the updated analysis for the 2018 PM2.5 Plan, the
State completed separate sensitivity analyses for the annual and 24-
hour standards and modeled only transportation-related sources in the
nonattainment area. The ratio the State is proposing to use for
transportation conformity purposes is derived from air quality modeling
that evaluated the effect of reductions in transportation-related
NOX and PM2.5 emissions in the SJV on ambient
concentrations at the Bakersfield-California Avenue, Bakersfield-Planz,
Fresno-Garland, and Fresno-Hamilton & Winery monitoring sites. The
modeling that the State performed to evaluate the effectiveness of
NOX and PM2.5 reductions on ambient 24-hour
concentrations showed NOX:PM2.5 ratios that range
from a high of 7.1 at the Bakersfield-California Avenue monitor to a
low of 6.0 at the two Fresno monitors.\238\ We find that the State's
approach is a reasonable method to use to develop ratios for
transportation conformity purposes. We therefore propose to approve the
6.5:1 NOX for PM2.5 trading mechanism as
enforceable components of the transportation conformity program for the
SJV for the 2012 annual PM2.5 NAAQS.
---------------------------------------------------------------------------

    \238\ 2018 PM2.5 Plan, App. D, D-126.
---------------------------------------------------------------------------

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

SIP revision. As a general matter, such approved budgets cannot be
superseded by revised budgets found adequate, but rather only through
approval of the revised budgets, unless the EPA specifies otherwise in
its approval of a SIP by limiting the duration of the approval to last
only until subsequently submitted budgets are found adequate.\239\
---------------------------------------------------------------------------

    \239\ 40 CFR 93.118(e)(1).
---------------------------------------------------------------------------

    In the submittal letter for the 2018 PM2.5 Plan, CARB
requested that we limit the duration of our approval of the budgets to
the period before the effective date of the EPA's adequacy finding for
any subsequently submitted budgets.\240\ The transportation conformity
rule allows us to limit the approval of budgets.\241\ However, we will
consider a state's request to limit an approval of its MVEBs only if
the request includes the following elements: \242\ (1) An
acknowledgement and explanation as to why the budgets under
consideration have become outdated or deficient; (2) a commitment to
update the budgets as part of a comprehensive SIP update; and (3) a
request that the EPA limit the duration of its approval to the period
before new budgets have been found to be adequate for transportation
conformity purposes.
---------------------------------------------------------------------------

    \240\ Letter dated May 9, 2019, from Richard W. Corey, Executive
Officer, CARB, to Mike Stoker, Regional Administrator, EPA Region
IX, 3.
    \241\ 40 CFR 93.118(e)(1).
    \242\ 67 FR 69141 (November 15, 2002), limiting our prior
approval of MVEBs in certain California SIPs.
---------------------------------------------------------------------------

    CARB's request includes an explanation for why the budgets have
become, or will become, outdated or deficient. In short, CARB has
requested that we limit the duration of the approval of the budgets in
light of the EPA's approval of EMFAC2017, an updated version of the
EMFAC2014 used for the budgets in the 2018 PM2.5 Plan.\243\
EMFAC2017 updates vehicle mix and emissions data of the previously
approved version of the EMFAC2014.
---------------------------------------------------------------------------

    \243\ On August 15, 2019, the EPA approved and announced the
availability of EMFAC2017, the latest update to the EMFAC model for
use by the State and local governments to meet CAA requirements. 84
FR 41717.
---------------------------------------------------------------------------

    In light of the EPA's approval of EMFAC2017, CARB explains that the
budgets in the 2018 PM2.5 Plan, which we are proposing to
approve in this action, will become outdated and will need to be
revised using EMFAC2017. In addition, CARB states that, without the
ability to replace the budgets using the budget adequacy process, the
benefits of using the updated data may not be realized for a year or
more after the updated SIP (with the EMFAC2017-derived budgets) is
submitted, due to the length of the SIP approval process. We find that
CARB's explanation for limiting the duration of the approval of the
budgets is appropriate and provides us with a reasonable basis for
limiting the duration of the approval of the budgets.
    We note that CARB has not committed to update the budgets as part
of a comprehensive SIP update, but as a practical matter, CARB must
submit a SIP revision that includes updated demonstrations as well as
the updated budgets to meet the adequacy criteria in 40 CFR
93.118(e)(4).\244\ Therefore, we do not need a specific commitment for
such a plan at this time. For the reasons provided above, and in light
of CARB's explanation for why the budgets will become outdated and
should be replaced upon an adequacy finding for updated budgets, we
propose to limit the duration of our approval of the budgets in the
2018 PM2.5 Plan to the period before we find revised budgets
based on EMFAC2017 to be adequate.
---------------------------------------------------------------------------

    \244\ Under 40 CFR 93.118(e)(4), the EPA will not find a budget
in a submitted SIP to be adequate unless, among other criteria, the
budgets, when considered together with all other emissions sources,
are consistent with applicable requirements for RFP and attainment.
40 CFR 93.118(e)(4)(iv).
---------------------------------------------------------------------------

    Lastly, in section IV.H of this proposed rule, the EPA is proposing
to disapprove the contingency measure element of the 2016
PM2.5 Plan, as amended in the 2018 PM2.5 Plan,
with respect to Moderate area requirements for the 2012
PM2.5 NAAQS. If the EPA were to finalize the proposed
disapproval of the 2012 PM2.5 NAAQS Moderate area
contingency measure element, the area would be eligible for a
protective finding under the transportation conformity rule because the
2016 PM2.5 Plan and 2018 PM2.5 Plan reflect
adopted control measures that fully satisfy the emissions reductions
requirements for RFP for years 2019 and 2022.\245\
---------------------------------------------------------------------------

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

V. Reclassification as Serious Nonattainment and Serious Area SIP
Requirements

A. Reclassification as Serious and Applicable Attainment Date

    Section 188 of the Act outlines the process for classification of
PM2.5 nonattainment areas and establishes the applicable
attainment dates. Under section 188(b)(1) of the Act, the EPA has
general authority to reclassify at any time before the applicable
attainment date any area that the EPA determines cannot practicably
attain the standard by such date. Accordingly, section 188(b)(1) of the
Act is a general expression of delegated rulemaking authority. In
addition, subparagraphs (A) and (B) of section 188(b)(1) mandate that
the EPA reclassify ``appropriate'' PM10 nonattainment areas
at specified time frames (i.e., by December 31, 1991, for the initial
PM10 nonattainment areas, and within 18 months after the SIP
submittal due date for subsequent nonattainment areas). These
subparagraphs do not restrict the EPA's general authority but simply
specify that, at a minimum, it must be exercised at certain times.\246\
---------------------------------------------------------------------------

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

    We have reviewed the air quality modeling and impracticability
demonstration in the 2016 PM2.5 Plan, as well as the air
quality modeling in the 2018 PM2.5 Plan. Based on our
review, we agree with the District's conclusion that implementation of
the State/District's SIP control strategy, including RACM/RACT and
additional reasonable measures, is insufficient to bring the SJV into
attainment of the 2012 PM2.5 NAAQS by the December 31, 2021
Moderate area attainment deadline. See sections IV.C and IV.F of this
proposed rule. In addition, we have reviewed recent PM2.5
monitoring data for SJV available in the EPA's Air Quality System (AQS)
database. These data show that annual PM2.5 levels in the
SJV continue to be above 12.0 [micro]g/m\3\, the numerical level of the
2012 PM2.5 standard, and the recent trends in the SJV annual
PM2.5 levels indicate that the SJV will not attain by the
end of 2021.\247\
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    \247\ EPA design value workbook dated May 24, 2021,
``pm25_designvalues_2018_2020_final_05_24_21.xlsx,'' worksheets
``Table1a'' and ``Table5a,'' and EPA, 2010-2020 AQS Design Value
Report, AMP480, June 30, 2021.
---------------------------------------------------------------------------

    In accordance with section 188(b)(1) of the Act, the EPA is
proposing to reclassify the SJV from Moderate to Serious nonattainment
for the 2012 annual PM2.5 standard of 12.0 [micro]g/m\3\,