ozone NAAQS to continue to study the feasibility of such standard for
the San Joaquin Valley specifically.
    With regard to efforts currently underway by the Bay Area AQMD, we
note that on March 15, 2023, Bay Area AQMD adopted amendments to Rule
9-4 (``Nitrogen Oxides from Fan Type Residential Central Furnaces'')
and Rule 9-6 (``Nitrogen Oxides Emissions from Natural Gas-Fired
Boilers and Water Heaters'').\306\ These rules govern point

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

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

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

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

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

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

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

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

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

D. Attainment Demonstration and Modeling

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

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

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

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

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

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

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

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

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

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

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

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

    \318\ Id. at 61.

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

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

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

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

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

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

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

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

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

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

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

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

E. Reasonable Further Progress and Quantitative Milestones

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

    \329\ General Preamble Addendum, 42015.
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    Attainment plans for PM nonattainment areas should include detailed
schedules for compliance with emissions control measures in the area
and provide corresponding annual emissions reductions to be achieved by
each milestone in the schedule.\330\ In reviewing an attainment plan
under subpart 4, the EPA considers whether the annual incremental
emissions reductions to be achieved are reasonable in light of the
statutory objective of timely attainment. Although early implementation
of the most cost-effective control measures is often appropriate,
states should consider both cost-effectiveness and pollution reduction
effectiveness when developing implementation schedules for control
measures and may implement measures that are more effective at reducing
PM2.5 earlier to provide greater public health
benefits.\331\
---------------------------------------------------------------------------

    \330\ Id. at 42016.
    \331\ Id.
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    In addition to the EPA's longstanding guidance on the RFP
requirements for PM, the Agency has established specific regulatory
requirements for the PM2.5 NAAQS in the PM2.5 SIP
Requirements Rule for purposes of satisfying the Act's RFP requirements
and provides related guidance in the preamble to the rule.
Specifically, under the PM2.5 SIP Requirements Rule, each
PM2.5 attainment plan must contain an RFP analysis that
includes, at minimum, the following four components: (1) an
implementation schedule for control measures; (2) RFP projected
emissions for direct PM2.5 and all PM2.5 plan
precursors for each applicable milestone year, based on the anticipated
control measure implementation schedule; (3) a demonstration that the
control strategy and implementation schedule will achieve reasonable
progress toward attainment between the base year and the attainment
year; and (4) a demonstration that by the end of the calendar year for
each triennial milestone date for the area, pollutant emissions will be
at levels that reflect either generally linear progress or stepwise
progress in reducing emissions on an annual basis between the base year
and the attainment year.\332\ Additionally, states should estimate the
RFP projected emissions for each quantitative milestone year by sector
on a pollutant-by-pollutant basis.\333\
---------------------------------------------------------------------------

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

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

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

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

    The CAA does not specify the starting point for counting the three-
year periods for quantitative milestones under CAA section 189(c). In
the General Preamble and General Preamble Addendum, the EPA interpreted
the CAA to require that the starting point for the first three-year
period be the due date for the Moderate area plan submission.\335\ In
keeping with this historical approach, the EPA established December 31,
2014, the deadline that the EPA established for a state's submission of
any additional attainment-related SIP elements necessary to satisfy the
subpart 4 Moderate area requirements for the 1997 PM2.5
NAAQS, as the starting point for the first three-year period under CAA
section 189(c) for the 1997 PM2.5 NAAQS in the San Joaquin
Valley.\336\
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    \335\ General Preamble, 13539, and General Preamble Addendum,
42016.
    \336\ 79 FR 31566 (final rule establishing subpart 4 Moderate
area classifications and deadline for related SIP submissions).
Although this final rule did not affect any action that the EPA had
previously taken under CAA section 110(k) on a SIP for a
PM2.5 nonattainment area, the EPA noted that states may
need to submit additional SIP elements to fully comply with the
applicable requirements of subpart 4, even for areas with previously
approved PM2.5 attainment plans, and that the deadline
for any such additional plan submissions was December 31, 2014. Id.
at 31569.
---------------------------------------------------------------------------

    Under the PM2.5 SIP Requirements Rule, each attainment
plan submission for an area designated nonattainment for the 1997
PM2.5 NAAQS before January 15, 2015, must contain
quantitative milestones to be achieved no later than three years after
December 31, 2014, and every three years thereafter until the milestone
date that falls within three years after the applicable attainment
date.\337\ If the area fails to attain, this post-attainment date
milestone provides the EPA with the tools necessary to monitor the
area's continued progress toward attainment while the state develops a
new attainment plan.\338\ Quantitative milestones must provide for
objective evaluation of RFP toward timely attainment of the
PM2.5 NAAQS in the area and include, at minimum, a metric
for tracking progress achieved in implementing SIP control measures,
including BACM and BACT, by each milestone date.\339\
---------------------------------------------------------------------------

    \337\ 40 CFR 51.1013(a)(4).
    \338\ 81 FR 58010, 58064.
    \339\ Id. at 58064 and 58092.
---------------------------------------------------------------------------

    Because the EPA designated the San Joaquin Valley area as
nonattainment for the 1997 annual PM2.5 NAAQS effective
April 5, 2005,\340\ the plan for this area must contain quantitative
milestones to be achieved no later than three years after December 31,
2014 (i.e., by December 31, 2017), and every three years thereafter
until the milestone date that falls within three years after the
applicable attainment date.\341\ For a Serious area attainment plan
with a statutory attainment date of December 31, 2015, the relevant
quantitative milestone year is December 31, 2017. However, as discussed
in Section III of this proposal, the area did not attain by the
statutory Serious area attainment date and evaluating reasonable
further progress toward that date does not make sense. We are therefore
evaluating the Serious area obligations based on the attainment date
the State must meet in a plan required under CAA section 189(d).\342\
To meet CAA section 189(d), the SJV PM2.5 Plan includes a
demonstration that the area will attain by December 31, 2023.
Therefore, in accordance with 40 CFR 51.1013(a)(4), the attainment plan
for this area must contain quantitative milestones to be achieved no
later than December 31, 2017, December 31, 2020, December 31, 2023, and
December 31, 2026.
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    \340\ 70 FR 944.
    \341\ 40 CFR 51.1013(a)(4).
    \342\ See CAA section 179(d); 40 CFR 51.1004(a)(3).
---------------------------------------------------------------------------

2. Summary of the State's Submission
    Appendix H (``RFP, Quantitative Milestones, and Contingency'') of
the 15 [micro]g/m\3\ SIP Revision contains the State's RFP
demonstration and quantitative milestones for the 1997 annual
PM2.5 NAAQS, and the Valley State SIP Strategy contains the
control measure commitments that CARB has identified as mobile source
quantitative milestones.\343\ Given the State's conclusions that
ammonia, SOX, and VOC emissions do not contribute
significantly to PM2.5 levels that exceed the 1997 annual
PM2.5 NAAQS in the San Joaquin Valley, as discussed in
Section IV.B of this proposed rule, the RFP demonstration provided by
the State addresses emissions of direct PM2.5 and
NOX.\344\ Similarly, the State developed quantitative
milestones based on the Plan's control strategy measures that achieve
reductions in emissions of direct PM2.5 and
NOX.\345\ Appendix H of the 15 [micro]g/m\3\ SIP Revision
identifies the milestone dates of December 31, 2017, December 31, 2020,
December 31, 2023, and December 31, 2026, for the 1997 annual
PM2.5 NAAQS.\346\ The RFP analysis in the Plan shows
generally linear progress toward attainment of the 1997 annual
PM2.5 NAAQS.
---------------------------------------------------------------------------

    \343\ Valley State SIP Strategy, Table 7 (identifying State
measures scheduled for action between 2017 and 2023, inter alia) and
CARB Resolution 18-49, ``San Joaquin Valley Supplement to the 2016
State Strategy for the State Implementation Plan'' (October 25,
2018), p. 5 (adopting State commitment to begin public processes and
propose for Board consideration the list of proposed SIP measures
outlined in the Valley State SIP Strategy and included in Attachment
A, according to the schedule set forth therein).
    \344\ 15 [micro]g/m\3\ SIP Revision, Appendix H, p. H-1.
    \345\ Id. at H-18 and H-19 (District milestones) and H-21 and H-
22 (State milestones).
    \346\ Id. at Table H-11.
---------------------------------------------------------------------------

    We describe the RFP analysis and quantitative milestones in the SJV
PM2.5 Plan in greater detail below.
Reasonable Further Progress
    The State addresses the RFP and quantitative milestone requirements
in Appendix H of the 15 [micro]g/m\3\ SIP Revision. The State estimates
that emissions of direct PM2.5 and NOX will
generally decline from the 2013 base year to the projected 2023
attainment year, and beyond to the 2026 post-attainment quantitative
milestone year. The Plan's emissions inventory shows that direct
PM2.5 and NOX are emitted by a large number and
range of sources in the San Joaquin Valley. Table H-2 in Appendix H
contains an anticipated implementation schedule for District regulatory
control measures and Table 4-8 in Chapter 4 of the 15 [micro]g/m\3\ SIP
Revision contains an anticipated implementation schedule for CARB
control measures in the San Joaquin Valley. Table H-5 in Appendix H
contains projected emissions for each quantitative milestone year.
These emissions levels reflect both baseline emissions projections and
commitments to achieve additional emission reductions through
implementation of new control measures by 2023.\347\
---------------------------------------------------------------------------

    \347\ Id. at tables H-3 (emissions projections based on baseline
measures), H-4 (reductions from control measure commitments), and H-
5 (emissions projections accounting for controls). The 15 [micro]g/
m\3\ SIP Revision includes commitments for reductions from new
control measures by 2023.
---------------------------------------------------------------------------

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

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

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

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

    \350\ 15 [micro]g/m\3\ SIP Revision, Chapter 4, Table 4-7.
    \351\ 15 [micro]g/m\3\ SIP Revision, Appendix H, Table H-4.
---------------------------------------------------------------------------

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

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

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

    \355\ 15 [micro]g/m\3\ SIP Revision, Appendix H, Table H-2.
    \356\ 15 [micro]g/m\3\ SIP Revision, Appendix D, Chapter IV, and
Appendix C.
---------------------------------------------------------------------------

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

F. Motor Vehicle Emission Budgets

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

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

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

    \376\ 40 CFR 51.1012(a), 51.1013(a)(2).
    \377\ 40 CFR 51.1013(a)(4) and 81 FR 58010, 58058 and 58063-
58064. Because the area has failed to attain the 1997 annual
PM2.5 NAAQS by the Serious area attainment date, the
applicable attainment date for the purposes of our evaluation is the
section 189(d) projected attainment date of December 31, 2023.
    \378\ 81 FR 58010, 58063-58064.
---------------------------------------------------------------------------

    PM2.5 plans should identify budgets for direct
PM2.5, NOX, and all other PM2.5
precursors for which on-road emissions are determined to significantly
contribute to PM2.5 levels in the area for each RFP
milestone year and the attainment year, if the plan demonstrates
attainment. All direct PM2.5 SIP budgets should include
direct PM2.5 from tailpipe, brake wear, and tire wear motor
vehicle emissions. With respect to emissions of VOC, SO2,
and/or ammonia, the transportation conformity provisions of 40 CFR part
93, subpart A, apply only if the EPA Regional Administrator or the
director of the state air agency has made a finding that
transportation-related emissions of these precursors within the area
are a significant contributor to the PM2.5 nonattainment
problem and has so notified the MPO and Department of Transportation
(DOT), or if the applicable implementation plan (or implementation plan
submission) includes any of these precursors in the approved (or
adequate) budget as part of the RFP, attainment, or maintenance
strategy.\379\ With respect to PM2.5 from re-entrained road
dust, the transportation conformity provisions of 40 CFR part 93,
subpart A apply if the EPA Regional Administrator or the director of
the state air agency has made a finding that re-entrained road dust
emissions within the area are a significant contributor to the
PM2.5 nonattainment problem and has so notified the MPO and
DOT, or if the applicable implementation plan (or implementation plan
submission) includes re-entrained road dust in the approved (or
adequate) budget as part of the reasonable further progress,
attainment, or maintenance strategy.\380\ Similarly, for
PM2.5 from construction emissions, the transportation
conformity provisions of 40 CFR part 93, subpart A apply if the area's
implementation plan identifies construction-related fugitive
PM2.5 as a significant contributor to the nonattainment
problem.\381\
---------------------------------------------------------------------------

    \379\ 40 CFR 93.102(b)(2)(v); see also Conformity Rule preambles
at 69 FR 40004, 40031-40034 (July 1, 2004) and 70 FR 24280, 24283-
24285 (May 6, 2005).
    \380\ 40 CFR 93.102(b)(3).
    \381\ 40 CFR 93.122(f); see also Conformity Rule preambles at 69
FR 40004, 40035-40036 (July 1, 2004).
---------------------------------------------------------------------------

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

    As noted above, the State included a trading mechanism to be used
in transportation conformity analyses that would be used in conjunction
with the budgets in the SJV PM2.5 Plan, as allowed for under
40 CFR 93.124(b). This trading mechanism would allow MPOs to use future
decreases in NOX emissions from on-road mobile sources to
offset any on-road increases in PM2.5 emissions using a 6.5
to 1 NOX to PM2.5 ratio in transportation
conformity determinations for the 1997 annual PM2.5 NAAQS.
To ensure that the trading mechanism does not affect the ability to
meet the NOX budget, the Plan provides that the
NOX emissions reductions available to supplement the
PM2.5 budget would only be those remaining after the
NOX budget has been met. The San Joaquin Valley MPOs will
have to document clearly the calculations used in the trading when
demonstrating conformity, along with any additional reductions of
NOX and PM2.5 emissions in the conformity
analysis. The trading calculations must be performed prior to the final
rounding to demonstrate conformity with the budgets.
    The EPA has reviewed the trading mechanism as described on pages D-
125 to D-127 in Appendix D of the 15 [micro]g/m\3\ SIP Revision and
finds it is appropriate for transportation conformity purposes in the
San Joaquin Valley for the 1997 annual PM2.5 NAAQS. The
methodology for estimating the trading ratio for conformity purposes is
essentially an update (based on newer modeling) of the approach that
the EPA previously approved for the 2008 PM2.5 Plan for the
1997 PM2.5 NAAQS \402\ and the 2012 PM2.5 Plan
for the 2006 24-hour PM2.5 NAAQS.\403\ The State's approach
in the previous plans was to model the ambient PM2.5 effect
of areawide NOX emissions reductions and of areawide direct
PM2.5 emissions reductions, and to express the ratio of
these modeled sensitivities as an inter-pollutant trading ratio.
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    \402\ 80 FR 1816, 1841 (January 13, 2015) (noting the EPA's
prior approval of budgets for the 1997 annual and 24-hour
PM2.5 standards in the 2008 PM2.5 Plan at 76
FR 69896).
    \403\ 81 FR 59876 (August 31, 2016).
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    In the updated analysis for the SJV PM2.5 Plan, the
State completed separate sensitivity analyses for the annual and 24-
hour NAAQS and modeled only transportation related sources in the
nonattainment area. The ratio the State is proposing to use for
transportation conformity purposes is derived from air quality modeling
that evaluated the effect of reductions in transportation-related
NOX and PM2.5 emissions in the San Joaquin Valley
on ambient concentrations at the Bakersfield-California Avenue,
Bakersfield-Planz, Fresno-Garland, and Fresno-Hamilton & Winery
monitoring sites. The modeling that the State performed to evaluate the
effectiveness of NOX and PM2.5 reductions on
ambient annual concentrations showed NOX to PM2.5
ratios that range from a high of 7.1 at the Bakersfield-Planz monitor
to a low of 6.0 at the two Fresno monitors.\404\ In a recent action on
the 2018 PM2.5 Plan for the 2012 annual PM2.5
NAAQS, we found that the State's approach is a reasonable method to use
to develop ratios for transportation conformity purposes and approved
the 6.5 to 1 NOX to PM2.5 trading mechanism as an
enforceable component of the transportation conformity program for the
San Joaquin Valley for the 2012 PM2.5 NAAQS.\405\ Here, we
similarly find that the State's approach is reasonable and propose to
approve the 6.5 to 1 NOX for PM2.5 trading
mechanism as enforceable components of the transportation conformity
program for the San Joaquin Valley for

the 1997 annual PM2.5 NAAQS. If approved, this trading ratio
will replace the 9 to 1 NOX to PM2.5 trading
ratio approved for the San Joaquin Valley for analysis years after 2014
for the 1997 annual PM2.5 NAAQS.\406\
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    \404\ 15 [micro]g/m\3\ SIP Revision, Appendix D, p. D-126.
    \405\ See 86 FR 49100, 49128 (September 1, 2021) (proposed rule)
and 86 FR 67343, 67346 (November 26, 2021) (final rule).
    \406\ 76 FR 69896.
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G. Nonattainment New Source Review Requirements Under CAA Section
189(e)

    Section 189(e) of the CAA specifically requires that the control
requirements applicable to major stationary sources of direct
PM2.5 also apply to major stationary sources of
PM2.5 precursors, except where the Administrator determines
that such sources do not contribute significantly to PM2.5
levels that exceed the NAAQS in the area.\407\ The control requirements
applicable to major stationary sources of direct PM2.5 in a
Serious PM2.5 nonattainment area include, at minimum, the
requirements of a nonattainment NSR permit program meeting the
requirements of CAA sections 172(c)(5) and 189(b)(3). As part of our
April 7, 2015 final action to reclassify the San Joaquin Valley area as
Serious nonattainment for the 1997 PM2.5 standards, we
established a May 7, 2016 deadline for the State to submit
nonattainment NSR SIP revisions addressing the requirements of CAA
sections 189(b)(3) and 189(e) of the Act for the 1997 PM2.5
NAAQS.\408\
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    \407\ General Preamble, 13539 and 13541-13542.
    \408\ 80 FR 18528, 18533.
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    California submitted nonattainment NSR SIP revisions to address the
subpart 4 requirements for the San Joaquin Valley Serious
PM2.5 nonattainment area on November 20, 2019.\409\ On June
28, 2023, the EPA finalized a limited approval and limited disapproval
of the nonattainment NSR SIP revisions.\410\ We are not taking any
further action on the submission at this time.
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    \409\ Letter dated November 15, 2019, from Richard W. Corey,
Executive Officer, CARB, to Michael Stoker, Regional Administrator,
EPA Region IX.
    \410\ EPA Region IX, ``Air Plan Revisions; California; San
Joaquin Valley Air Pollution Control District; Stationary Source
Permits,'' final rule signed June 28, 2023.
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V. Environmental Justice Considerations

    Executive Order 12898 requires that federal agencies, to the
greatest extent practicable and permitted by law, identify and address
disproportionately high and adverse human health or environmental
effects of their actions on minority and low-income populations.\411\
Additionally, Executive Order 13985 directs federal government agencies
to assess whether, and to what extent, their programs and policies
perpetuate systemic barriers to opportunities and benefits for people
of color and other underserved groups,\412\ and Executive Order 14008
directs federal agencies to develop programs, policies, and activities
to address the disproportionate health, environmental, economic, and
climate impacts on disadvantaged communities.\413\
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    \411\ 59 FR 7629 (February 16, 1994).
    \412\ 86 FR 7009 (January 25, 2021).
    \413\ 86 FR 7619 (February 1, 2021).
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    To identify environmental burdens and susceptible populations in
underserved communities in the San Joaquin Valley nonattainment area
and to better understand the context of our proposed action on these
communities, we rely on the EPA's August 2022 screening-level analysis
for PM2.5 in the San Joaquin Valley using the EPA's
environmental justice (EJ) screening and mapping tool
(``EJSCREEN'').414 415 Maps showing census block level data
for the San Joaquin Valley from EJSCREEN are included in the EPA's 1997
Annual PM2.5 TSD. The results of this analysis are being
provided for informational and transparency purposes.
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    \414\ EJSCREEN provides a nationally consistent dataset and
approach for combining environmental and demographic indicators.
EJSCREEN is available at https://www.epa.gov/ejscreen/what-ejscreen.
The EPA used EJSCREEN to obtain environmental and demographic
indicators representing each of the eight counties in the San
Joaquin Valley. We note that the indicators for Kern County are for
the entire county. While the indicators might have slightly
different numbers for the San Joaquin Valley portion of the county,
most of the county's population is in the San Joaquin Valley
portion, and thus the differences would be small. These indicators
are included in EJSCREEN reports that are available in the
rulemaking docket for this action.
    \415\ EPA Region IX, ``EJSCREEN Analysis for the Eight Counties
of the San Joaquin Valley Nonattainment Area,'' August 2022.
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    Our screening-level analysis indicates that the ``Demographic
Index'' for each of the eight counties in the San Joaquin Valley is
above the national average, ranging from 48 percent in Stanislaus
County to 61 percent in Tulare County, compared to 36 percent
nationally. The Demographic Index is the average of an area's percent
minority and percent low income populations, i.e., the two populations
explicitly named in Executive Order 12898.\416\ All eight counties are
above the national average for demographic indices of ``Linguistically
Isolated Population'' and ``Population with Less than High School
Education.''
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    \416\ EJSCREEN reports environmental indicators (e.g., air
toxics cancer risk, Pb paint exposure, and traffic proximity and
volume) and demographic indicators (e.g., people of color, low
income, and linguistically isolated populations). The value for a
particular indicator measures how the community of interest compares
with the state, the EPA region, or the national average. For
example, if a given location is at the 95th percentile nationwide,
this means that only 5 percent of the U.S. population has a higher
value than the average person in the location being analyzed.
EJSCREEN also reports EJ indexes, which are combinations of a single
environmental indicator with the EJSCREEN Demographic Index. For
additional information about environmental and demographic
indicators and EJ indexes reported by EJSCREEN, see EPA, ``EJSCREEN
Environmental Justice Mapping and Screening Tool--EJSCREEN Technical
Documentation,'' Section 2 (September 2019).
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    With respect to pollution, all eight counties are at or above the
97th percentile nationally for the PM2.5 index and seven of
the eight counties in the San Joaquin Valley are at or above the 90th
percentile nationally for the PM2.5 EJ index, which is a
combination of the Demographic Index and the PM2.5 index.
Most counties are also above the 80th percentile for each of 11
additional EJ indices included in the EPA's EJSCREEN analysis. In
addition, several counties are above the 90th percentile for certain EJ
indices, including, for example, the Ozone EJ Index (Fresno, Kern,
Madera, Merced, and Tulare counties), the National Air Toxics
Assessment (NATA) Respiratory Hazard EJ Index (Madera and Tulare
counties), and the Wastewater Discharge Indicator EJ Index (Merced, San
Joaquin, Stanislaus, and Tulare counties).\417\
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    \417\ Notably, Tulare County is above the 90th percentile for 6
of the 12 EJ indices in the EPA's EJSCREEN analysis, including the
PM2.5 EJ Index, which is the highest value among all San
Joaquin Valley counties.
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    This proposed action would approve the State's plan for attaining
the 1997 annual PM2.5 NAAQS. Information on the 1997 annual
PM2.5 NAAQS and its relationship to negative health impacts
can be found at 62 FR 38652 (July 18, 1997). We expect that this action
and resulting emissions reductions will generally be neutral or
contribute to reduced environmental and health impacts on all
populations in the San Joaquin Valley, including people of color and
low-income populations. At a minimum, this action would not worsen
existing air quality and is expected to ensure the area is meeting
requirements to attain and/or maintain air quality standards. Further,
there is no information in the record indicating that this action is
expected to have disproportionately high or adverse human health or
environmental effects on a particular group of people.

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

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

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

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

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

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

    \419\ 77 FR 65294, 65302 (October 26, 2012) (footnotes omitted).

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

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

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

    \421\ Id. at 700.

    What is appropriate for purposes of necessary assurances can vary
depending upon the nature of the issues in a particular situation.
Thus, the EPA evaluates a state's compliance with CAA 110(a)(2)(E)(i)
on a case-by-case basis.
    For purposes of background context, Title VI prohibits recipients
of federal financial assistance from discriminating on the basis of
race, color, or national origin. Under the EPA's nondiscrimination
regulations, which implement Title VI and other federal civil rights
laws,\422\ recipients of EPA financial assistance are prohibited from
taking actions in their programs or activities that are intentionally
discriminatory and/or have an unjustified disparate impact.\423\ This
includes policies, criteria, or methods of administering programs that
are neutral on their face but have the effect of discriminating.\424\
Under the EPA's regulation, recipients of EPA financial assistance are
also required to have in place certain procedural safeguards, including
grievance procedures that assure the prompt and fair resolution of
external discrimination complaints.\425\
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    \422\ 40 CFR. part 7 and part 5.
    \423\ 40 CFR 7.30 and 7.35.
    \424\ 40 CFR 7.35(b).
    \425\ 40 CFR 7.90.
---------------------------------------------------------------------------

    The EPA carries out its mandate to ensure that recipients of EPA
financial assistance comply with their nondiscrimination obligations by
investigating administrative complaints filed with the EPA alleging
discrimination prohibited by Title VI and the other federal civil
rights laws; \426\ initiating affirmative compliance reviews; \427\ and
providing technical assistance to recipients to assist them in meeting
their Title VI obligations. The EPA notes that at the time of this
proposal, no Title VI complaint has been filed against CARB or the
District regarding the SJV PM2.5 Plan for the 1997 annual
PM2.5 NAAQS. Also, the EPA (through the Office of External
Civil Rights Compliance (OECRC)) has not initiated and is not currently
conducting a compliance review of either CARB or SJVUAPCD.
---------------------------------------------------------------------------

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

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

State Submission

    On June 15, 2023, CARB submitted to the EPA supplemental
information from CARB and the District (``Title VI Supplement'') in
which the State outlines its consideration of Title VI in the context
of SIP development in order to provide necessary assurances for
purposes of CAA section 110(a)(2)(E)(i).\430\
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    \430\ Letter dated June 15, 2023, from Steven S. Cliff,
Executive Officer, CARB, to Martha Guzman, Regional Administrator,
EPA Region IX, with enclosures titled ``Title VI of the Civil Rights
Act of 1964: CARB Supplemental Information for EPA in Support of 15
[micro]g/m\3\ Annual PM2.5 Standard'' (``CARB Title VI
Supplement'') and ``San Joaquin Valley Air Pollution Control
District Write-Up on Title VI of the Civil Rights Act of 1964:
Supplemental Information for EPA in Support of 15 [micro]g/m\3\
Annual PM2.5 Standard'' (``District Title VI
Supplement'').
---------------------------------------------------------------------------

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

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

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

    Specific to the SJV PM2.5 Plan for the 1997 annual
PM2.5 NAAQS, the submission further describes the early and
enhanced public engagement processes that CARB and the District
undertook during the development and approval of the 2016 State SIP
Strategy, Valley State SIP Strategy, 2018 PM2.5 Plan, and 15
[micro]g/m\3\ SIP Revision, all of which formed the basis for the SJV
PM2.5 Plan for the 1997 annual PM2.5 NAAQS. CARB
notes that the State prioritized public participation and describes the
numerous public meetings and workshops held in Sacramento, Fresno, and
Bakersfield for community-based organizations and other stakeholders
during the preparation of the SJV PM2.5 Plan and related
control measures, including the Heavy-Duty I/M measure.\432\ CARB and
the District also note that Plan documents were made available for
public review 30 days prior to board consideration, and that board
hearings and workshops offered simultaneous Spanish translation
services and that interpretation in other languages was made available
on request.\433\
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    \432\ CARB Title VI Supplement, pp. 3-4.
    \433\ CARB Title VI Supplement, p. 3, and District Title VI
Supplement.
---------------------------------------------------------------------------

    In addition to discussing the State's processes for public
engagement during the development of the SJV PM2.5 Plan for
the 1997 annual PM2.5 NAAQS, the State's Title VI Supplement
also describes CARB's recent and ongoing efforts to develop and
implement the 2022 State SIP Strategy.\434\ These efforts include
soliciting public input on potential control measures through meetings
with individual community-based organizations, workshops, and webinars,
and publishing a list of the suggested measures from the public to seek
additional input. Seve ral of the measures suggested by the public were
ultimately adopted in the 2022 State SIP Strategy,\435\ and CARB notes
that public processes will continue as each measure is developed,
adopted, and implemented by the State.