Air Quality State Implementation Plans; Approvals and Promulgations: California; 1997 Annual Fine Particulate Matter Serious and Clean Air Act Section 189(d) Nonattainment Area Requirements; San Joaquin Valley, CA, 86581-86608 [2023-27088]
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BILLING CODE 9110–04–P
ENVIRONMENTAL PROTECTION
AGENCY
40 CFR Part 52
[EPA–R09–OAR–2023–0263; FRL–10941–
02–R9]
Air Quality State Implementation
Plans; Approvals and Promulgations:
California; 1997 Annual Fine
Particulate Matter Serious and Clean
Air Act Section 189(d) Nonattainment
Area Requirements; San Joaquin
Valley, CA
Table of Contents
Environmental Protection
Agency (EPA).
ACTION: Final rule.
AGENCY:
The Environmental Protection
Agency (EPA or ‘‘Agency’’) is taking
final action to approve portions of state
implementation plan (SIP) revisions
submitted by the State of California to
meet Clean Air Act (CAA or ‘‘Act’’)
requirements for the 1997 annual fine
particulate matter (PM2.5) national
ambient air quality standards (NAAQS
or ‘‘standards’’) in the San Joaquin
Valley PM2.5 nonattainment area.
Specifically, the EPA is approving those
portions of the submitted SIP revisions
as they pertain to the Serious
nonattainment area and CAA section
189(d) requirements for the 1997 annual
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SUMMARY:
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PM2.5 NAAQS, except for the
requirement for contingency measures
which will be addressed in a separate
rulemaking. In addition, the EPA is
approving the 2020 and 2023 motor
vehicle emissions budgets and the
trading mechanism for use in
transportation conformity analyses for
the 1997 annual PM2.5 NAAQS.
DATES: This rule is effective on January
16, 2024.
ADDRESSES: The EPA has established a
docket for this action under Docket ID
No. EPA–R09–OAR–2023–0263. All
documents in the docket are listed on
the https://www.regulations.gov
website. Although listed in the index,
some information is not publicly
available, e.g., Confidential Business
Information (CBI) or other information
whose disclosure is restricted by statute.
Certain other material, such as
copyrighted material, is not placed on
the internet and will be publicly
available only in hard copy form.
Publicly available docket materials are
available through https://
www.regulations.gov, or please contact
the person identified in the FOR FURTHER
INFORMATION CONTACT section for
additional availability information. If
you need assistance in a language other
than English or if you are a person with
a disability who needs a reasonable
accommodation at no cost to you, please
contact the person identified in the FOR
FURTHER INFORMATION CONTACT section.
FOR FURTHER INFORMATION CONTACT:
Ashley Graham, Geographic Strategies
and Modeling Section (AIR–2–2), EPA
Region IX, 75 Hawthorne Street, San
Francisco, CA 94105. By phone: (415)
972–3877 or by email at
graham.ashleyr@epa.gov.
SUPPLEMENTARY INFORMATION:
Throughout this document, ‘‘we,’’ ‘‘us,’’
and ‘‘our’’ refer to the EPA.
I. Summary of the Proposed Action
II. Public Comments and EPA Responses
A. Comments From Central California
Environmental Justice Network (CCEJN)
B. Comments From Central Valley Air
Quality Coalition (CVAQ)
C. Comments From a Private Individual
III. Motor Vehicle Emissions Budgets and
Transportation Conformity
IV. Environmental Justice Considerations
V. Final Action
VI. Statutory and Executive Order Reviews
I. Summary of the Proposed Action
On July 14, 2023, in accordance with
CAA section 110(k)(3), the EPA
proposed to approve portions of SIP
revisions submitted by the California
Air Resources Board (CARB) to meet
CAA requirements for the 1997 annual
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PM2.5 NAAQS in the San Joaquin Valley
PM2.5 nonattainment area.1 The San
Joaquin Valley is classified as a Serious
nonattainment area for the 1997 annual
PM2.5 NAAQS and is also subject to
CAA section 189(d) requirements
because of the failure of the area to
attain the 1997 annual PM2.5 NAAQS by
the area’s original Serious area
attainment date (i.e., December 31,
2015). The EPA’s determination that the
area failed to attain by the original
December 31, 2015 attainment date
triggered the requirement for the State to
submit the SIP revisions on which the
EPA is taking final action in this
document.2
The SIP revisions on which we
proposed action are those portions of
the ‘‘2018 Plan for the 1997, 2006, and
2012 PM2.5 Standards’’ (‘‘2018 PM2.5
Plan’’) 3 and the ‘‘San Joaquin Valley
Supplement to the 2016 State Strategy
for the State Implementation Plan’’
(‘‘Valley State SIP Strategy’’) 4 that
pertain to the 1997 annual PM2.5
NAAQS, and the ‘‘Attainment Plan
Revision for the 1997 Annual PM2.5
Standard’’ (‘‘15 mg/m3 SIP Revision’’).5
CARB submitted the 2018 PM2.5 Plan
and Valley State SIP Strategy to the EPA
as a revision to the California SIP on
May 10, 2019, and submitted the 15 mg/
m3 SIP Revision on November 8, 2021.
We refer to these three submissions
collectively as the ‘‘SJV PM2.5 Plan’’ or
‘‘Plan.’’ The SJV PM2.5 Plan was
developed jointly by the San Joaquin
Valley Unified Air Pollution Control
District (SJVUAPCD or ‘‘District’’) and
CARB and addresses Serious area
nonattainment plan and CAA section
189(d) requirements for the 1997 annual
PM2.5 NAAQS in the San Joaquin
Valley, except for the requirement for
contingency measures. The Plan
includes the State’s demonstration that
the area will attain the 1997 annual
PM2.5 NAAQS by December 31, 2023.
Following submittal of the SJV PM2.5
Plan, CARB transmitted to the EPA two
technical supplements providing
additional information in support of the
Plan. The first supplement, submitted
on March 30, 2023, included documents
titled ‘‘Ammonia: Supplemental
Information for EPA in Support of 15
mg/m3 Annual PM2.5 Standard, March
1 88
FR 45276.
FR 84481 (November 23, 2016).
3 The 2018 PM
2.5 Plan was adopted by the San
Joaquin Valley Unified Air Pollution Control
District on November 15, 2018, and by CARB on
January 24, 2019.
4 The Valley State SIP Strategy was adopted by
CARB on October 25, 2018.
5 The ‘‘15 mg/m3 SIP Revision’’ was adopted by
the San Joaquin Valley Unified Air Pollution
Control District on August 19, 2021, and adopted
by CARB on September 23, 2021.
2 81
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2023’’ (‘‘March 2023 Ammonia
Supplement’’) and ‘‘Building
Electrification Technical Supplement
for the 1997 Annual PM2.5 NAAQS’’
(‘‘March 2023 Building Heating
Supplement’’). The second supplement
was submitted on June 15, 2023, and
included information on the State’s
consideration of Title VI of the Civil
Rights Act of 1964 (‘‘Title VI’’) in the
context of SIP development to provide
necessary assurances for purposes of
CAA section 110(a)(2)(E)(i) (‘‘Title VI
Supplement’’).6
The EPA proposed to approve the best
available control measures/best
available control technology (BACM/
BACT) demonstration,7 the five percent
annual emissions reduction
demonstration, the attainment
demonstration (including air quality
modeling), the reasonable further
progress (RFP) demonstration, and the
quantitative milestones demonstration
in the SJV PM2.5 Plan as meeting the
Serious nonattainment area and CAA
section 189(d) planning requirements
for the 1997 annual PM2.5 NAAQS. We
also proposed to find that the previously
approved 8 2013 base year emissions
inventories continue to satisfy the
requirements of CAA section 172(c)(3)
and 40 CFR 51.1008 for purposes of
both the Serious area and the CAA
section 189(d) attainment plans, and to
find that the forecasted inventories for
the years 2017, 2018, 2019, 2020, 2023,
and 2026 provide an adequate basis for
the BACM, RFP, five percent, and
modeled attainment demonstration
analyses. Finally, we proposed to
approve the motor vehicle emissions
budgets for 2020 and 2023 and the
6 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 mg/m3 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
mg/m3 Annual PM2.5 Standard’’ (‘‘District Title VI
Supplement’’).
7 As discussed in Section III.B of the proposal, a
section 189(d) plan must address any outstanding
Moderate or Serious area requirements that have
not previously been approved. Because we have not
previously approved a subpart 4 RACM
demonstration for the San Joaquin Valley
nonattainment area, we also proposed to approve
the BACM/BACT demonstration in the SJV PM2.5
Plan as meeting the subpart 4 RACM/RACT
requirement for the area. (88 FR 45276, 45322).
8 On November 26, 2021, the EPA finalized a
partial approval and partial disapproval of the 2018
PM2.5 Plan for the 1997 annual PM2.5 NAAQS,
including approval of the 2013 base year emissions
inventory in the Plan. 86 FR 67329.
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trading mechanism provided for use in
transportation conformity analyses.9
Please see our July 14, 2023 proposed
rulemaking for additional background
and a detailed explanation of the
rationale for our proposed action.
II. Public Comments and EPA
Responses
The public comment period for the
proposed rulemaking opened on July 14,
2023, the date of its publication in the
Federal Register, and closed on August
14, 2023. During this period, the EPA
received three comment submissions
from the following entities: (1) a
coalition of six environmental and
community organizations (collectively
referred to herein as ‘‘CCEJN’’),10 (2) a
coalition of eight environmental and
community organizations (collectively
referred to herein as ‘‘CVAQ’’),11 and (3)
a private citizen commenter.12 We
respond to the comments herein.
A. Comments From Central California
Environmental Justice Network (CCEJN)
1. Necessary Assurances Required by
CAA Section 110(a)(2)(E)
Comment 1.A: CCEJN questioned the
EPA’s proposed approval of the SJV
PM2.5 Plan because of concerns about
the adequacy of the necessary
assurances that the State provided in the
Title VI supplement. The commenter
contends that to comply with CAA
section 110(a)(2)(E), a state’s necessary
assurances must relate to a state’s
nonattainment plan SIP submission
itself, not merely the public processes
carried out while preparing the plan or
state laws and policies outside of the
plan. The commenter claims that the
Title VI Supplement fails to do this
because it ‘‘has nothing to do with’’ the
9 An adequacy finding for the 2020 and 2023
motor vehicle emissions budgets was effective on
February 25, 2022. (87 FR 7834, February 10, 2022).
10 Comment letter dated and received August 11,
2023, including 36 attachments, addressed to
Ashley Graham, EPA Region IX. The six
environmental and community organizations, in
order of appearance in the letter, are the Central
California Environmental Justice Network, the
Central Valley Air Quality Coalition, Earthjustice,
the Leadership Counsel for Justice and
Accountability, the National Parks Conservation
Association, and Sierra Club—Kern-Kaweah
Chapter.
11 Comment letter dated and received August 14,
2023, addressed to Martha Guzman, Regional
Administrator, EPA Region IX. The eight
environmental and community organizations, in
order of appearance in the letter, are the Central
Valley Air Quality Coalition, Earthjustice, Sierra
Club—Kern-Kaweah Chapter, the National Parks
Conservation Association, the Central California
Environmental Justice Network, Little Manila
Rising, and Valley Improvement Projects.
12 Comment letter dated and received August 14,
2023, from Richard Grow, to Docket ID No. EPA–
R09–OAR–2023–0263.
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specific contents of the SJV PM2.5 Plan.
As an example, the commenter points to
the State’s lack of a Title VI analysis
supporting its decision to not regulate
ammonia as part of its PM2.5 reduction
strategy and contends that this example
indicates that the State has failed to
provide adequate necessary assurances.
Additionally, CCEJN asserts that the
EPA’s analysis of the Plan must
consider how the Plan itself complies
with Title VI and that the EPA did not
do so in its proposal.
Response 1.A: The EPA agrees with
the commenter that CAA section
110(a)(2)(E)(i) requires that a state
provide necessary assurances that
implementing the SIP submission at
issue would not be prohibited by Title
VI. However, the EPA disagrees with the
commenter that the necessary
assurances provided by CARB, in
conjunction with the substantive
elements of the Plan itself, are
insufficient to show that
implementation of the Plan is not
prohibited by Title VI, consistent with
CAA section 110(a)(2)(E)(i). The EPA
explained its rationale regarding its
evaluation of the necessary assurances
and CAA section 110(a)(2)(E)(i) in detail
in our proposal.13
As a point of clarification, the
commenter includes references to
‘‘compliance with Title VI’’ as the
relevant inquiry for purposes of
necessary assurances under CAA
section 110(a)(2)(E)(i). The EPA does not
agree with this characterization of its
responsibilities under the CAA.14 In the
proposal action, the EPA clearly noted
that ‘‘[t]he EPA’s proposed SIP approval
does not constitute a formal finding of
compliance with Title VI or 40 CFR part
7.’’ 15 The EPA further noted that
‘‘[a]pproval of this SIP submission for
purposes of CAA 110(a)(2)(E)(i) does not
affect the EPA’s discretion to enforce
Title VI and/or the EPA’s civil rights
regulations.’’ 16 Without making a
formal finding of compliance with Title
VI, the EPA believes the analysis in the
EPA’s proposed approval and in this
13 88
FR 45276, 45319–45321.
El Comite´ para el Bienestar de Earlimart et
al. v. EPA, 786 F.3d 688 (9th Cir. 2015) (‘‘El Comite´
effectively contends the EPA should have evaluated
California’s assurances the same way the EPA
would have to deal with a pending Title VI
complaint setting forth allegations of a current
violation. El Comite´’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.’’).
15 88 FR 45276, 45321.
16 Id.
14 See
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final rulemaking is consistent with CAA
section 110(a)(2)(E)(i).17
With respect to the substance of the
State’s submission, the EPA disagrees
with the commenter that the public
processes surrounding the development
and implementation of an attainment
plan have no bearing on necessary
assurances under CAA section
110(a)(2)(E)(i). As stated in the proposal,
‘‘[w]hat 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.’’ 18 Further, the EPA has
discretion to determine what assurances
are necessary and may require more or
different information as needed in other
SIP actions.19 For example, in other
contexts, the EPA has identified public
participation as an established approach
for recipients of EPA assistance to
provide meaningful access to programs
and activities.20 Therefore, the EPA does
not agree with the contention that
methods of providing for public
participation are not relevant to the
analysis of necessary assurances under
CAA section 110(a)(2)(E)(i).
In the Title VI Supplement, the State
described 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 mg/m3
SIP Revision, all of which formed the
basis for the SJV PM2.5 Plan for the 1997
annual PM2.5 NAAQS. It also described
steps the State and District took to
solicit and respond to public input
following the local adoption of the Plan
and to implement the control measures
and strategy outlined in the Plan. These
approaches are beyond minimum public
notice and comment requirements and
provide relevant information and
important context of the necessary
assurances under CAA section
110(a)(2)(E)(i) that the Plan was adopted
and will be implemented into the future
in a manner that is not prohibited by
Title VI.
17 See El Comite
´ para el Bienestar de Earlimart et
al. v. EPA, 786 F.3d 688 (9th Cir. 2015) (‘‘Section
110(a)(2)(E) . . . 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.’’)
18 88 FR 45276, 45320.
19 See id.
20 See, e.g., https://www.epa.gov/external-civilrights/external-civil-rights-guidance. Although
information on this website is not specific to CAA
section 110(a)(2)(E)(i) necessary assurances, it
provides information regarding public participation
and information provided to recipients of EPA
assistance.
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Similarly, the descriptions of State
measures like Assembly Bill 617 (‘‘AB
617’’) and the development of
community air monitoring networks
provide relevant context for the
regulatory landscape in which the State
will implement the Plan, as well as the
intent of the regulators. The EPA
believes the State initiatives to prevent
or diminish potential health-related
impacts to communities most impacted
by air pollution also, in part, provide
assurances that the implementation of
the Plan is not prohibited by Title VI in
a manner consistent with CAA section
110(a)(2)(E)(i). The State’s Civil Rights
Policy, too, provides additional support
for the conclusion that implementation
of the Plan would not be prohibited by
Title VI. For example, the policy would
allow for members of the public to
notify and file a formal complaint with
the State that an alleged violation of
Title VI is occurring ‘‘during the
administration of [the State’s]
programs.’’ 21 Taken together, these
various State processes and initiatives
support the conclusion that the State
provided necessary assurances that
implementation of the plan would not
be prohibited by Title VI.
The commenter points to one primary
substantive deficiency in the Plan that
they believe indicates the State has not
demonstrated compliance with CAA
section 110(a)(2)(E)(i): The commenter
claims that ammonia is a major
precursor of PM2.5 and that the policy
decision ‘‘to decline to regulate
ammonia implicates disparate treatment
and/or disparate impact, yet CARB
provides no necessary assurances that
this policy decision does not violate
Title VI.’’ The EPA’s proposed and final
actions, based upon the State’s SIP
submissions, reflect the EPA’s
agreement that ammonia is not a
significant precursor of PM2.5 for the
purposes of the 1997 annual PM2.5
NAAQS in the San Joaquin Valley. As
described in more detail in Section
II.A.3 of this document, this final
determination comes following the
EPA’s review of the State’s submittal
and request for additional information
to support the State’s decision not to
regulate ammonia for this NAAQS, as
well as the EPA’s review of the exhibits
and attachments from the commenter.
Included in the State’s submittal and
March 2023 Ammonia Supplement are
estimates of the level of emissions
reductions possible with a suite of
potential ammonia control measures,
justifications for why many of these
measures are not feasible or are already
being implemented in the area, and
21 Title
PO 00000
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86583
ultimately, why the State has chosen to
focus on reducing direct PM2.5 and NOX
to reduce PM2.5 concentrations in the
San Joaquin Valley air basin. The EPA
believes the technical information
provided by the State to support its
decision not to regulate ammonia for
purposes of the 1997 annual PM2.5
NAAQS provides adequate necessary
assurances that the implementation of
this Plan will not be prohibited by Title
VI.
The EPA recognizes that the San
Joaquin Valley area has previously
struggled to attain the 1997 annual
PM2.5 NAAQS and that the Demographic
Index analysis the EPA completed as a
part of the proposed approval indicates
the area includes communities of color
and low-income populations above the
national average. However, as explained
in this response and in our proposal, the
EPA believes the information in the
record contains adequate necessary
assurances consistent with CAA section
110(a)(2)(E)(i). This analysis is based in
part on technical analyses such as that
the modeling in the State’s and District’s
Plan shows attainment for these NAAQS
by the applicable attainment date and
that the control strategy for PM2.5 takes
into consideration the unique
atmospheric conditions in the San
Joaquin Valley air basin in which the
PM2.5 response to reductions in
ammonia emissions would be relatively
small. Thus, based on the existing
technical record before the EPA, we find
that the State has adequately provided
necessary assurances that the
implementation of the Plan is consistent
with CAA section 110(a)(2)(E)(i).
Comment 1.B: Next, CCEJN contends
that the policies cited by CARB in its
Title VI supplement to support its
necessary assurances, e.g., AB 617,
community air monitoring networks,
and CARB’s Civil Rights Policy, are not
enforceable parts of the submitted Plan
(pursuant to CAA section 110(a)(2)(A)),
cannot lead to credited emissions
reductions for SIP purposes, and thus
cannot be relied upon as necessary
assurances.
Response 1.B: The EPA disagrees that
necessary assurances must themselves
be enforceable parts of a plan. While in
some instances a state may submit
additional enforceable measures as a
component of necessary assurances, the
EPA believes that this is not a
requirement. The commenter cites the
CAA section 110(a)(2)(A) requirement
that plans include enforceable
emissions limitations and other control
measures as a basis for the assertion that
necessary assurances must be
enforceable and part of the plan. The
EPA agrees that nonattainment plans
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must contain enforceable emissions
limitations and other control
measures—but this does not mean that
CAA section 110(a)(2)(E)(i) necessary
assurances must themselves be
emissions limitations or control
measures. The EPA interprets section
110(a)(2)(E)(i) as allowing an
‘‘assurance’’ to include an analysis of
the plan. In this context, a state
providing adequate information to the
EPA to provide necessary assurances
that the state is not prohibited by Title
VI from carrying out the plan in the SIP
submission is sufficient. In the proposal
action, the EPA explained the rationale
for this approach, including citing to
relevant case law finding that ‘‘what
assurances are ‘necessary’ is left to the
EPA’s discretion.’’ 22 This is consistent
with necessary assurances that the EPA
requires when needed for other issues
related to section 110(a)(2)(E)(i). For
example, states also provide necessary
assurances concerning the adequacy of
personnel, funding, and state law
authority to implement a SIP
submission, and the EPA generally
relies on facts, analyses, and other forms
of assurances from the state for these
purposes—not enforceable measures
(that is, the EPA generally does not
require SIP-approved rules that are
incorporated by reference into the Code
of Federal Regulations to provide such
necessary assurances). There may be
circumstances under which the EPA
would expect a state to provide a state
law provision for inclusion into the SIP
in order to provide such necessary
assurances for these other requirements,
but this is not generally the case.
Where a necessary assurances
analysis concludes that additional
enforceable measures are needed, a state
would also include such new measures
in the SIP submission, but necessary
assurances need not necessarily
themselves constitute such measures, as
the commenter suggests. In this case, the
EPA has concluded that the information
provided by the State concerning its
existing policies and programs provides
adequate necessary assurances that the
State’s implementation of the SIP
submissions at issue would not be
prohibited by Title VI.
2. Emissions Inventory
Comment 2.A: CCEJN states that the
soil NOX emissions estimate of
approximately 10 tons per day (tpd)
used in the modeling emissions
inventory was dubious when the State
submitted the Plan in 2018 and that the
22 88 FR 45276, 45320. See also, El Comite
´ para
el Bienestar de Earlimart et al. v. EPA, 786 F.3d 688
(9th Cir. 2015).
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estimate is clearly inaccurate based on
more recent studies, which the
commenter claims suggest soil NOX may
contribute as much as 100 tpd to total
NOX emissions. The commenter also
asserts that studies suggest that soil NOX
emissions are likely driven primarily by
agriculture and therefore should be
considered anthropogenic. To support
these assertions, the commenter
references Exhibit A to the letter
(‘‘Exhibit A’’), which summarizes 10
studies from 2015–2023, from which the
author concludes that 9 of the studies
indicate that standard soil NOX
parameterizations underestimate
agricultural soil NOX emissions by a
factor of 2 to 10.
CCEJN further states that ‘‘[t]he state
has acknowledged that its existing
inventory may be outdated, and it has
begun the process of studying NOX
emissions from soil in order to update
the inventory for future submissions to
EPA,’’ but that its use of the existing
inventory in the interim ‘‘. . . is
unlawful because it is based exclusively
on inertia, and ‘the EPA cannot simply
recite ‘‘scientific uncertainty’’ to evade
its statutory duty to update
regulations’ ’’ (citing A Cmty. Voice v.
EPA, 997 F.3d 983, 994 (9th Cir. 2021)).
The commenter suggests that ‘‘[i]nstead,
the state must make an updated good
faith estimate—if not a perfect
estimate—of emissions, taking into
account that the Clean Air Act is
‘preventative’ and ‘precautionary’ in
nature,’’ and asserts that such estimate
would undoubtedly be higher than the
estimate in the current inventory and
would identify significant
anthropogenic soil NOX emissions.
Based on its analysis, CCEJN
concludes that the EPA must disapprove
the inventory because it is neither
‘‘current’’ nor ‘‘accurate’’ and that
failure to do so is arbitrary and
capricious.
Response 2.A: The EPA acknowledges
the information provided by CCEJN in
its comments and in the studies
described in Exhibit A suggesting that
soil NOX emissions may be higher than
have typically been estimated in the
past. The studies cited by the
commenter rely on variants of several
emissions estimation approaches,
including efforts to achieve better
agreement between air quality models
and satellite measurements, and to
correlate satellite measurements over
croplands with the expected soil
temperature and moisture dependence
of soil NOX emissions. While most of
the studies cited by the commenter were
published after the State developed the
emissions and conducted the modeling
for the 2018 PM2.5 Plan upon which the
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15 mg/m3 SIP Revision is based, the EPA
would not characterize the studies as
providing ‘‘updated’’ emissions that
would make the estimates in the 2018
PM2.5 Plan obsolete, as suggested by the
commenter. Rather, as discussed further
in the remainder of this response, we
find that some recent studies provide
evidence that soils are an important
NOX source, and several provide
alternative estimates of soil NOX
emissions using various approaches.
The EPA agrees that there is evidence
suggesting soil NOX emissions may be
higher than previously estimated but
disagrees with the characterization in
Exhibit A that 9 out of the 10 studies
conclude that California soil NOX is
underestimated by a factor of 2 or more.
That was the conclusion of two of the
studies, those described in Almaraz et
al. (2018) 23 and Sha et al. (2021).24 Luo
et al. (2022) 25 did not opine on how
their estimate compares with prior
estimates, though the authors did
provide an estimate that the author of
Exhibit A notes implies that prior
estimates are largely underestimated.
The other studies provide evidence
consistent with soil NOX as an
important source or suggest a stronger
temperature dependence for soil NOX
emissions compared to previous
approaches.
While there is evidence suggesting
soil NOX emissions may be higher than
previously estimated, there are
conflicting conclusions in the literature.
Because the inventories in the SJV PM2.5
Plan reflect the State’s best estimate
based on the information available at
the time the Plan was developed, the
EPA does not believe a change in the
soil NOX emissions estimation approach
relied on in the SJV PM2.5 Plan is
warranted at this time. There is a need
to reconcile the disagreement among
studies by examining the differing
assumptions, techniques, data sources,
locations, and time periods covered.
Such further examination may also help
resolve the substantial uncertainty and
variability of the proportion of soil NOX
emissions that can be attributed to
anthropogenic sources such as
agricultural fertilizer application.
The EPA further disagrees with
CCEJN’s assertion that the State relies
23 Almaraz et al. (2018), Agriculture is a major
source of NOX pollution in California, Science
Advances, 4(1), 2018, doi:10.1126/sciadv.aao3477.
24 Sha et al. (2021), Impacts of soil NO emission
X
on O3 air quality in rural California, Environmental
Science & Technology, 55(10), 7113–7122,
doi:10.1021/acs.est.0c06834.
25 Luo et al. (2022), Integrated Modeling of U.S.
Agricultural Soil Emissions of Reactive Nitrogen
and Associated Impacts on Air Pollution, Health,
and Climate, Environmental Science & Technology,
56 (13), 9265–9276. doi:10.1021/acs.est.1c08660.
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on the soil NOX emissions estimates in
its existing inventory due to ‘‘inertia.’’
As noted by the commenter, the State
has effectively acknowledged that its
methodology for estimating soil NOX
emissions may need to be updated when
it shared its plans to convene a subject
matter expert review panel to assess the
state of the science on soil NOX
emissions and make recommendations
for future estimates.26 These efforts
indicate that the State is taking the issue
seriously and attempting to address it,
as acknowledged by the commenter.
However, in exploring possible
improvements to its soil NOX estimation
approach, the State is not disavowing
the approach used in the SJV PM2.5
Plan, nor is there a widely accepted soil
NOX emissions inventory approach that
the State is willfully refusing to use.
Depending on the outcomes of the
review panel’s work, the State may find
that its current approach provides the
best estimate and retain such approach,
or the State may determine that an
alternative approach would provide a
more accurate estimate and use such
approach moving forward.
For the SJV PM2.5 Plan, the State used
the DeNitrification-DeComposition
model (DNDC) to estimate the 10 tpd of
soil NOX emissions used in the
modeling.27 The approach is supported
by research conducted in the same time
frame as studies cited by the commenter
and therefore the EPA does not consider
the State’s approach to be outdated. The
emissions inventory in the Plan was
among the work that led to the paper by
Guo et al. (2020),28 which was cited in
Exhibit A as among the recent research
on soil NOX. Guo et al. (2020) did not
find that soil NOX emissions are
significantly underestimated in the
State’s emissions inventory. Rather, the
study examined evidence from satellite
26 SJVUAPCD, 2023 PM
2.5 Plan for Attainment of
the Federal 2012 Annual PM2.5 Standard, Public
Workshop, slide 16, https://www.valleyair.org/
Workshops/postings/2023/05-11-23_PM25/
presentation.pdf. (A recording of the workshop is
also cited in the comment letter in fn. 39).
27 Email dated May 26, 2020, from Jeremy Avise,
CARB, to Scott Bohning, EPA Region IX, Subject:
‘‘Soil NOX in ARB’s modeling’’, with attached
poster ‘‘Preliminary Assessment of Soil NOX
Emissions from Agricultural Cropland in the San
Joaquin Valley’’; ‘‘Estimating Nitrogen Emissions
from California’s Agricultural Lands’’, March 5,
2019, presentation by Mike Fitzgibbon, CARB, at
2019 California Climate & Agriculture Summit,
https://calclimateag.org/2019summit/.
28 Guo et al. (2020), Assessment of Nitrogen Oxide
Emissions and San Joaquin Valley PM2.5 Impacts
From Soils in California, Journal of Geophysical
Research: Atmospheres, 125(24), doi:10.1029/
2020JD033304. Note that a web document with a
DOI or Digital Object Identifier, such as 10.1029/
2020JD033304, may be found via prefixing doi.org/
to the doi, as in: https://doi.org/10.1029/
2020JD033304.
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retrievals and ground-based
measurements that indicate that the
State’s approach provides an accurate
emissions inventory for the San Joaquin
Valley. The EPA believes that the
DNDC-based soil NOX emissions used in
the modeling are a good faith estimate
consistent with the State’s current view
of the state of the science, and that the
State’s estimate is acceptable for use in
the modeling emissions inventory in the
SJV PM2.5 Plan for the 1997 annual
PM2.5 NAAQS.
The EPA acknowledges that there is
evidence that soil NOX emissions have
historically been underestimated,
including evidence from some studies
finding that satellite observations of
column NO2 (total amount of NO2 in a
vertical column of the atmosphere)
indicate that soil NOX emissions are
higher than predictions by
photochemical models using emissions
estimates from older soil NOX
parameterizations. The commenter
describes some of such evidence in
Exhibit A. However, the case for soil
NOX emissions being significantly
underestimated in the San Joaquin
Valley is not as settled as CCEJN’s
comment implies. The studies cited by
the commenter differ in the questions
they attempt to address, their
assumptions and analytical approaches,
their data analysis techniques and
metrics, and in the differing
environmental conditions in the
locations and time periods they cover.
In the remainder of this response, we
identify statements from the ten
research papers listed in Exhibit A to
show that their support for a
substantially greater soil NOX emissions
for the San Joaquin Valley is not
definitive, and that there is not an
agreed upon method to estimate a
missing increment of emissions if one is
in fact needed. Note that these points
are not meant to discredit the work of
the respective authors but rather to
illustrate that there are varying factors
that require greater investigation to
determine the magnitude of soil NOX
emissions in the San Joaquin Valley.
Given these complicating factors and
uncertainties, the EPA requests that
CARB and the District continue their
work to examine their current
methodology for estimating soil NOX
emissions, and as appropriate, revise
their methodology based on the findings
of the expert review panel and the latest
available research.
Oikawa et al. (2015) 29 measured NOX
emissions from sorghum plots after
29 Oikawa et al. (2015), Unusually high soil
nitrogen oxide emissions influence air quality in a
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86585
applying fertilizer, and explored the
effect of higher soil NOX emissions on
the performance of an air quality model
by comparing the model results with
satellite NO2 column observations and
surface measurements. The study
authors concluded that soil NOX
emissions would need to be 10 or more
times higher to match observations.
However, surface measurements were
not consistently underestimated in the
model, and increasing emissions in the
model to match the satellite retrievals
led to overestimates in emissions at the
surface derived from measurements of
soil NOX emissions fluxes. The paper
also noted that global estimates of soil
NOX emissions from other studies vary
by a factor of three (ranging from 9 to
27 Tg per year), indicating a high level
of uncertainty. The study conclusions
suggest that soil NOX emissions are
largely underestimated but the
magnitude of the underestimate is not
quantified.
Parrish et al. (2017) 30 focuses on
understanding trends in ozone design
values, noting a difference in the San
Joaquin Valley trend in comparison
with other California air basins. The
authors note that the difference may
partially be accounted for by the higher
agricultural activity in the Valley, for
which controls have not been
implemented as extensively as for other
anthropogenic sources. While this
explanation could also hold for
agricultural soil NOX, that particular
issue is not explored.
Exhibit A cites Kleeman et al.
(2019) 31 as providing evidence of a
missing source of NOX emissions that
could help correct a ‘‘consistent
underprediction’’ in nitrate
concentrations. The EPA believes this
underprediction was overstated. For the
January average of the three model years
reported, there was a modest
underprediction of nitrate in the model
base cases without soil NOX compared
to a somewhat larger overprediction
when soil NOX emissions were added;
whereas for the 2010 model year, nitrate
was overpredicted in the base case and
the overprediction was worsened in the
high-temperature agricultural region. Nat.
Commun., 6:8753, doi:10.1038/ncomms9753.
30 Parrish et al. (2017), Ozone Design Values in
Southern California’s Air Basins: Temporal
Evolution and U.S. Background Contribution. J.
Geophys. Res. Atmos., 122, 11166–11182,
doi:10.1002/2016JD026329.
31 Kleeman, M., A. Kumar, and A. Dhiman,
‘‘Investigative Modeling of PM2.5 Episodes in the
San Joaquin Valley Air Basin during Recent Years’’
(CARB Contract No. 15–301, 2019), available at
https://ww2.arb.ca.gov/sites/default/files/classic/
research/apr/past/15-301.pdf.
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soil NOX case.32 In the conclusion, the
authors state that ‘‘further research is
required to more accurately estimate
winter emissions rates of soil NOX and
to account for year-to-year variations
driven by changes in meteorological
conditions, fertilizer application rates,
and irrigation practices,’’ and that the
tests conducted ‘‘do not definitely prove
that the missing emissions source is
indeed fertilized agricultural soils.
Future measurements should be made
in the rural portions of the SJV to
further test the hypothesis that soil NOX
emissions are a significant factor in the
air quality cycles within the region.’’ 33
The EPA interprets such conclusions as
an acknowledgement that additional
research is needed, with a focus on
wintertime conditions when San
Joaquin Valley PM2.5 concentrations are
highest.
The author of Exhibit A summarizes
a result from Chen et al. (2020),34 noting
acceptable PM2.5 model performance
despite overly low atmospheric mixing
heights. But the author goes on to
suggest that overly low mixing heights
should have led to PM2.5
overpredictions; the good performance
therefore may imply that the PM2.5
precursor emissions were too low. The
study also found that rural site column
NO2 was underpredicted by 25 percent
relative to NO2 columns derived from
surface-based measurements, suggesting
that soil NOX emissions are
underestimated. Thus, the study authors
acknowledge that soil NOX emissions
may need to be further examined.
However, they also note good agreement
between modeled column NO2 and the
NO2 columns derived from surfacebased measurements at the urban sites
of Fresno and Bakersfield, where NO2 is
double that of the rural sites, and state
that ‘‘it is unlikely that NOX emissions
from croplands are comparable to
mobile sources’’ (the main source of
NOX emissions). That is, the NOX
emissions increase that would be
needed to increase the model
predictions by 25 percent for the lowNO2 rural sites is unlikely to be
comparable to the NOX emissions
driving the high NO2 urban sites. This
finding supports further exploration of
soil NOX emissions, and a possible
underestimate, but does not imply a
large underestimate in soil NOX
emissions.
at 60 and 63.
at 77.
34 Chen et al. (2020), Modeling air quality in the
San Joaquin valley of California during the 2013
Discover-AQ field campaign, Atmospheric
Environment: X, Volume 5, January 2020, 100067,
doi:10.1016/j.aeaoa.2020.100067.
Wang et al. (2021) 35 explored the
relatively modest downward trend in
satellite column NO2 measurements
after 2009, as compared to the steady
decrease in anthropogenic NOX
emissions, and the role of soil NOX
emissions in this apparent discrepancy.
They found better model agreement
with satellite column NO2 when they
increased the temperature
responsiveness of their soil NOX
emissions estimates, especially at high
temperatures. This change also
improved the correlation between
modeled column NO2 and satellite
column NO2 in the central United
States. This correlation is an important
finding, implying soil NOX emissions
may be underestimated. However, it
should be noted that in absolute terms,
even without soil NOX, the model
simulation overpredicted the NO2
concentration relative to the satellite
retrieval. The authors acknowledge that
there are many reasons why the
predictions might not match the
observations. The authors cite an
uncertainty of 35 percent in the satellite
NO2 columns, and the uncertainty in the
satellite retrieval encompasses all of the
results, from the zero soil NOX scenario
to the increased soil NOX scenario.36
The EPA views this as a large enough
uncertainty to limit confidence in at
least some of the study conclusions.
Wang et al. (2021) states that the
downward trend in the satellite column
NO2 is smaller than the downward trend
in anthropogenic NOX emissions, and
that the discrepancy is greater for the
central U.S. than for the eastern or
western U.S. Since the San Joaquin
Valley is in the west, the EPA interprets
this result as indicating that there is less
of a potential need for increases in soil
NOX emissions estimates in the San
Joaquin Valley relative to the central
U.S. to resolve the discrepancy. The
authors also cited another study in
which the apparent discrepancy
between the trends in modeled versus
surface-level ambient measurements (as
opposed to the satellite retrieval) was
found to be within the bounds of the
uncertainty of the ambient
measurements. The study provides a
strong impetus for exploring soil NOX
emissions and their potential increased
rate at higher temperatures but does not
provide evidence that soil NOX
emissions are significantly
underestimated in the San Joaquin
Valley.
32 Id.
33 Id.
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35 Wang et al (2021), Improved modelling of soil
NOX emissions in a high temperature agricultural
region: role of background emissions on NO2 trend
over the US, Environ. Res. Lett., 16, doi:10.1088/
1748–9326/ac16a3.
36 Id. at Figure 3.
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To evaluate the human health and
climate benefits of reducing reactive
nitrogen emissions, Luo et al. (2022) 37
used the Fertilizer Emission Scenario
Tool for CMAQ (FEST–C) to generate
soil NOX emissions estimates for every
U.S. county, including those counties in
the San Joaquin Valley. Exhibit A notes
that the FEST–C-derived San Joaquin
Valley county total emissions of soil
NOX is 100 tpd compared to CARB’s
emissions inventory for all
anthropogenic NOX which amounts to
roughly 200 tpd. The study used a
different emissions model than the
model used by CARB, underscoring the
need to explore why emissions models
yield such different results. The study
did not validate the model-derived NO2
predictions using satellite retrievals or
ground-based measurements, so it does
not provide direct evidence that soil
NOX emissions are underestimated for
the San Joaquin Valley.
Wang et al. (2023) 38 explored trends
in satellite column NO2 and ground
level measurements, and the role of
lightning and soil NOX in explaining
spatial and temporal distributions of
NO2. Among other results, they found
that temperature and soil moisture,
which are important drivers of soil NOX
emissions, were highly correlated with
satellite column NO2 in rural areas of
California, including crop lands. This
suggests soil NOX is an important source
of NOX near crop lands. The study
examined trends in NOX over time
rather than attempting to quantify soil
NOX emissions and therefore does not
provide direct evidence that soil NOX
emissions are underestimated for the
San Joaquin Valley.
Finally, three studies cited in Exhibit
A, Almaraz et al. (2018), Guo et al.
(2020), and Sha et al. (2021), provided
estimates of soil NOX emissions in
California. Almaraz et al. (2018) 39
estimated soil NOX emissions using a
top-down approach based on aircraft
measurements as well as the Integrated
Model for the Assessment of the Global
Environment (IMAGE) soil model. Guo
et al. (2020) 40 compared satellite
measurements of NO2 with CMAQ air
quality model predictions using soil
37 Luo et al. (2022), Integrated Modeling of U.S.
Agricultural Soil Emissions of Reactive Nitrogen
and Associated Impacts on Air Pollution, Health,
and Climate, Environmental Science & Technology,
2022, 56 (13), 9265–9276. doi:10.1021/
acs.est.1c08660.
38 Wang et al (2023), Satellite NO trends reveal
2
pervasive impacts of wildfire and soil emissions
across California landscapes, Environ. Res. Lett., 18,
doi:10.1088/1748–9326/acec5f.
39 Almaraz et al. (2018), Agriculture is a major
source of NOX pollution in California, Science
Advances, 4(1), 2018, doi:10.1126/sciadv.aao3477.
40 Guo et al. (2020), op. cit.
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NOX emissions from the DNDC soil
model. Sha et al. (2021) 41 conducted a
similar measurement-model comparison
but using the Weather Research and
Forecasting model coupled with
Chemistry (WRF-Chem) air quality
model and the Berkeley Dalhousie Iowa
Soil NO Parameterization (BDISNP) soil
model. The IMAGE and BDISNP models
are empirical or parametric models.
They rely on emissions factors that are
derived from empirical measurements
and that may vary by land use,
precipitation, and temperature, but do
not incorporate algorithms that reflect
the underlying physical principles. The
DNDC model used in Guo at al. (2020)
and in the State’s emissions inventory is
a biogeochemical or mechanistic model.
It also uses measurements for validation
but includes detailed consideration of
the individual physical and biological
processes in soils that lead to NOX
emissions and their dependence on
factors like the soil’s various nitrogenand carbon-containing species,
moisture, and temperature.
Comparisons between the results
described in Almaraz et al. (2018), Guo
et al. (2020), and Sha et al. (2021) show
large disagreements.42 Almaraz et al.
(2018) estimated that soil NOX
emissions from fertilized croplands
account for 32 percent of California NOX
emissions, Sha et al. (2021) estimated
soil NOX emissions comprise 40.1
percent of California’s total NOX
emissions, while Guo et al. (2020)
estimate that soil NOX emissions are
only 1.1 percent of California
anthropogenic NOX emissions. (As
noted earlier in this response, the DNDC
model emissions estimation work
performed for the Guo et al. (2020)
study was also the basis for the State’s
soil NOX emissions estimate.) The
fraction of nitrogen applied as fertilizer
released as NOX to the atmosphere was
estimated by Almaraz et al. (2018) to be
15 percent, while 7 other studies
reviewed by Guo et al. (2020) estimate
it to be 2 percent or less. Furthermore,
there is an additional possible
discrepancy between the work
described in Wang et al. (2021) 43 and
Wang et al. (2023),44 and the results in
Guo et al. (2020). The former two found
correlations between satellite-derived
column NO2 over agricultural areas and
41 Sha et al. (2021), Impacts of soil NO emission
X
on O3 air quality in rural California, Environmental
Science & Technology, 55(10), 7113–7122,
doi:10.1021/acs.est.0c06834.
42 The EPA also compared these studies in
approving California’s 2020 emissions inventory
submittal. 87 FR 59015, 59017–59019 (February 9,
2022).
43 Wang et al. (2021), op. cit.
44 Wang et al. (2023), op. cit.
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modeled soil emissions, suggesting soil
NOX as a driver of NO2 there. However,
using correlations and ratios of NOX to
CO among monitoring sites, and satellite
column NO2 retrievals, Guo et al. (2020)
found little difference between the
diurnal and seasonal temporal variation
at rural sites compared to urban sites,
consistent with a larger contribution of
emissions from urban sources rather
than rural soils. Higher soil NOX
emissions would increase summer
emissions more in rural areas than in
urban areas.
Despite widely differing estimates of
the relative portion of California’s NOX
emissions inventories attributable to soil
NOX in Almaraz et al. (2018), Sha et al.
(2021), and Guo et al. (2020), each study
reported high agreement between its
modeled and its observed soil NOX
emissions. Reconciling the differences
in input data used in the models, such
as fertilizer and irrigation amounts and
timing; other inputs to the air quality
models; and data analysis techniques
would be necessary for a process-based
understanding of the differences in the
contribution and magnitude of soil NOX
emissions estimates between models.
There is also a need for additional
measurements of soil NOX emissions
fluxes for various locations and
conditions to help develop and validate
soil models.
The various authors acknowledge
considerable uncertainty in their work.
While Almaraz et al. (2018) suggest that
soil NOX emissions may be significantly
underestimated using current
techniques, the study acknowledges the
limited number of surface
measurements that were available for
purposes of validating the model results
and that, where observations exist, there
is a large range in observed values due
to varying soil conditions (e.g., relating
to temperature, moisture, and fertilizer
application). The ‘‘top-down’’ NOX
emissions estimates derived from
aircraft measurements relied upon in
the study also reflect a significant
degree of uncertainty, reported at 190
tpd plus or minus 130 tpd, i.e., plus or
minus 68 percent. The authors
acknowledge the limited number of
surface measurements that were
available for purposes of comparing
with the model results, the difficulty in
comparing the model results with the
observations, and the need for more
field measurements. Guo et al. (2020)
stated that obtaining an emissions factor
correlating NOX emissions to fertilizer
application from the presently available
data in various studies (including
Almaraz et al. (2018)) would be
‘‘difficult or impossible’’ due to the
sparseness of data collected in terms of
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sampling length, sampling frequency,
and the episodic nature of nitrogen
gases from soil.
Most of the discussion herein
concerns the varying estimates of
overall total soil NOX emissions.
However, how those emissions are
distributed in time and space are also of
great importance for understanding the
effect of NOX emissions on ambient
PM2.5 concentrations. PM2.5
concentrations in the San Joaquin
Valley are highest in the cool, moist
winter, whereas soil NOX emissions are
highest in the warm, dry summer. For
modeling PM2.5 concentrations, it is
especially important that the soil NOX
approach that is used performs well
under wintertime conditions. Also
important is how the approach reflects
soil composition, soil management
practices, and fertilizer application,
each of which vary in time and space.
Adopting a different soil NOX emissions
estimation approach is not a matter of
simply replacing one estimate of total
soil NOX with another. Rather, it
requires ensuring that the approach
accurately reflects the spatial and
temporal variation of the many factors
affecting emissions and of the emissions
themselves.
In light of the uncertainties and
disagreements among studies, the EPA
does not believe that the available
research provides sufficient certainty
about the magnitude and proportion of
soil NOX emissions to warrant a revision
to the State’s inventory for purposes of
the SJV PM2.5 Plan.45 The EPA is not
convinced that any revised estimate
developed by the State at this time
would be verifiably more accurate than
the inventory in the Plan. A revision to
the State’s inventory approach may be
warranted in the future pending the
State’s ongoing work in this area and the
most up-to-date understanding of soil
NOX emissions, as discussed earlier in
this response. The EPA encourages the
State to continue its ongoing work to
convene a subject matter expert review
panel to assess the state of the science
on soil NOX emissions, to keep abreast
of the latest research, and to update its
estimation methodologies, as
appropriate. However, for purposes of
the SJV PM2.5 Plan for the 1997 annual
PM2.5 NAAQS that is the subject of this
action, we find that the State relied on
a reasonable methodology that is
supported by the research literature.
Thus, we conclude that the State
45 The EPA reached a similar conclusion in
approving California’s 2020 emissions inventory
submittal. 87 FR 59015, 59017–59019 (February 9,
2022).
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provided an accurate, up-to-date
emissions inventory for NOX.
Comment 2.B: Regarding the motor
vehicle emissions modeling, CCEJN
points to a previous statement from the
EPA, saying that ‘‘it could approve an
outdated inventory so long as the
inventory was built using the ‘latest
EPA-approved’ emission model ‘at the
time [the State] developed the
submission.’ ’’ The commenter asserts
that the EPA now ‘‘proposes to abandon
both the statutory text and the alreadylax requirement to use the most recent
EPA-approved model,’’ by allowing the
State to rely on a model that is a decade
old when two more recent models are
available, one of which (EMFAC2017)
shows higher attainment-year emissions
of both NOX and PM2.5. CCEJN contends
that the State and the EPA speculate
that the higher values would not affect
the attainment demonstration. However,
CCEJN asserts that the effect on the
attainment demonstration is unknown
and that it is also unknown what the
effects would be on the precursor
demonstration, which the commenter
claims relies on low estimates of NOX in
2023 to conclude that the State need not
regulate ammonia.
Finally, the commenter states that the
‘‘EPA’s decision to abandon its recently
adopted standard that inventories
should be built using the ‘latest EPAapproved’ emission model is arbitrary
and capricious,’’ asserting that the EPA
is ‘‘simply resistant to the idea that a
current inventory must be used’’ and
has lost litigation over this issue (citing
Sierra Club v. EPA, 671 F.3d 955 (9th
Cir. 2012)), and claiming that ‘‘. . .the
agency is therefore bending over
backwards to adopt whatever standard
will allow the state to continue to use
the outdated inventory.’’
Response 2.B: The EPA disagrees with
CCEJN’s claims that we are resistant to
require, or have changed our position,
that inventories must be developed
using the latest EPA-approved
emissions model available at the time
the State developed the SIP submission
and that our proposed action to reaffirm
the base year inventory is arbitrary and
capricious. As discussed in our
proposal, the SJV PM2.5 Plan relies on
much of the same technical information
and analyses from the 2018 PM2.5 Plan,
including the emissions inventories.46
The EPA previously found, for purposes
of the 1997 annual PM2.5 NAAQS as
well as other PM2.5 standards, that these
inventories were based on the most
current and accurate information
available to the State and District at the
time they were developing the 2018
46 88
FR 45276, 45279.
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PM2.5 Plan and inventories, including
the latest version of California’s mobile
source emissions model that had been
approved by the EPA at the time,
EMFAC2014.47 Thus, as part of our
prior action on the 2018 PM2.5 Plan for
the 1997 annual PM2.5 NAAQS, we
approved the emissions inventories as
meeting the Serious area and CAA
section 189(d) requirements for the 1997
annual PM2.5 NAAQS.48
In the EPA’s final action approving
the base year inventories in the 2018
PM2.5 Plan for the 1997 annual PM2.5
NAAQS, the EPA addressed concerns
raised by a commenter about the use of
EMFAC2014.49 The EPA discussed the
timeline for the State’s submittal of the
emissions inventories in the 2018 PM2.5
Plan relative to the EPA’s approval of
EMFAC2014 and EMFAC2017,
explaining that EMFAC2014 was the
most current mobile source model
available for emissions inventory
development purposes at the time the
State was developing the plan.
Nevertheless, at that time, we
considered comparisons between
EMFAC2014 and EMFAC2017 in the
2013 base year as provided by CARB in
its ‘‘Staff Report, Proposed SIP Revision
for the 15 mg/m3 Annual PM2.5 Standard
for the San Joaquin Valley’’ (‘‘CARB
Staff Report’’).50 Based on our review of
the State’s analysis, we concluded that
the 2013 base year emissions
inventories in the 2018 PM2.5 Plan were
comprehensive, accurate, and current,
consistent with the requirements of
CAA section 172(c)(3) and 40 CFR
51.1008.
Given that the 15 mg/m3 SIP Revision
was submitted to the EPA by the State
as an ‘‘administrative revision’’ to the
2018 PM2.5 Plan and relies on much of
the same technical information that was
developed for the 2018 PM2.5 Plan, the
State continued to rely on the
previously approved emissions
inventories from the 2018 PM2.5 Plan.
However, to address the most up-to-date
information available, in addition to the
EMFAC2017 model results noted earlier
in this response, the State provided to
47 The EPA previously approved the emissions
inventories in the 2018 PM2.5 Plan as they pertain
to the Serious area and 189(d) requirements for the
1997 annual PM2.5 NAAQS (86 FR 67329,
November 26, 2021), the Serious area and 189(d)
requirements for the 1997 24-hour PM2.5 NAAQS
(87 FR 4503, January 28, 2022), the Serious area
requirements for the 2006 24-hour PM2.5 NAAQS
(85 FR 44192, July 22, 2020), and the Moderate area
planning requirements for the 2012 annual PM2.5
NAAQS (86 FR 67343, November 26, 2021).
48 86 FR 67329.
49 Id. at 67332–67334.
50 CARB, ‘‘Staff Report, Proposed SIP Revision for
the 15 mg/m3 Annual PM2.5 Standard for the San
Joaquin Valley,’’ release date August 13, 2021.
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the EPA comparisons between the
estimated annual NOX and PM2.5
emissions developed for the 2018 PM2.5
Plan using EMFAC2014 with those
developed using the most recent EPAapproved version of EMFAC,
EMFAC2021.51 CARB’s analysis
included comparisons between all three
EMFAC models for both the 2020 RFP
year and the 2023 attainment year.52 As
the commenter correctly notes, model
results from EMFAC2017 indicate
higher NOX and PM2.5 emissions in the
2023 attainment year than those derived
for the same year using EMFAC2014.
However, EMFAC2021, which was the
most recent EPA-approved model at the
time of the EPA’s proposal,53 indicates
that NOX and PM2.5 emissions in the
2023 attainment year are lower than
those derived for the same year using
EMFAC2014.
As discussed in the EPA’s technical
support document (TSD) for our
proposal,54 the differences in emissions
estimates for mobile sources between
the three EMFAC model versions
correspond to differences of
approximately two percent or less of the
regional emissions inventories for PM2.5
and NOX for the 2023 attainment year.55
Using the sensitivity of the PM2.5 design
value per tpd of emissions modeled by
the State, the EPA assessed the effects
of the various EMFAC model version
results on the attainment demonstration
in the Plan.56 Based on our technical
analysis, we determined that although
the NOX and PM2.5 emissions estimates
in the 2023 attainment year are higher
in EMFAC2017 than in EMFAC2014,
the effect on the PM2.5 concentrations of
0.07 mg/m3 is sufficiently small that the
attainment demonstration remains
valid.57 Furthermore, more up-to-date
emissions data from EMFAC2021 show
lower emissions of NOX and PM2.5 in
the attainment year, indicating that the
attainment modeling results in the Plan
derived using EMFAC2014 are
conservative. The same is true for the
modeling for the precursor
demonstration—the lower NOX
estimates derived using EMFAC2021
would produce lower sensitivities of
PM2.5 to ammonia, since they would
increase the abundance of ammonia
51 88
FR 45276, 45284–45285.
52 Id.
53 The EPA approved the use of EMFAC2021 for
use in SIP development on November 15, 2022 (87
FR 68483).
54 EPA, ‘‘Technical Support Document, San
Joaquin Valley PM2.5 Plan Revision for the 1997
Annual PM2.5 NAAQS,’’ April 2023.
55 Id. at 53.
56 Spreadsheet ‘‘EMFAC update effect on annual
1997 p.m.2.5 NAAQS attainment
demonstration.xlsx,’’ EPA Region IX, May 1, 2023.
57 Id.
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relative to NOX (since particulate
ammonium nitrate formation would be
less limited by, and so less sensitive to,
the amount of ammonia). Therefore, the
State’s conclusions based on their use of
EMFAC2014 are conservative relative to
if it had used the most up-to-date EPAapproved model, EMFAC2021. Thus, we
disagree with the assertions that the
effects of the various EMFAC versions
on the attainment demonstration and
precursor demonstration are unknown
and find that reliance on the previously
approved emissions inventories is
acceptable.
Finally, we also disagree with the
commenter’s assertion (citing Sierra
Club) 58 that the EPA has lost litigation
over the issue that a current inventory
must be used. In Sierra Club, the Ninth
Circuit remanded the EPA’s March 2010
approval of an ozone attainment plan
for the San Joaquin Valley submitted in
2004, holding that the EPA’s failure to
consider new emissions data that the
State had submitted in 2007 as part of
a separate ozone plan rendered the
EPA’s action arbitrary and capricious
under the Administrative Procedure
Act.59 The decision in that case rested
on the unreasonableness of the EPA’s
failure to address the new emissions
data. The court found the EPA’s action
arbitrary and capricious because of its
‘‘reliance on old data without
meaningful comment on the
significance of more current compiled
data’’ and concluded that ‘‘it was
unreasonable for EPA summarily to rely
on the point of view taken [in
longstanding policy] without advancing
an explanation for its action based on
‘the facts found and the choice
made.’ ’’ 60
For purposes of this action, the EPA
has reviewed the emissions data derived
using more recent versions of the
EMFAC model provided by CARB,
consistent with the holding in Sierra
Club. Based on our technical analysis of
the latest information available
described earlier in this response, we
determined that the precursor and
attainment demonstrations are valid.
58 Sierra Club v. EPA, 671 F.3d 955 (9th Cir.
2012).
59 Id. The court also noted that the EPA’s action
was inconsistent with the court’s holding in Ass’n
of Irritated Residents (AIR) v. EPA, 632 F.3d 584
(9th Cir. 2011) (amended and superseded by Ass’n
of Irritated Residents v. U.S. EPA, 686 F.3d 668, 671
(9th Cir. 2012)), which ‘‘supports the proposition
that if new information indicates to EPA that an
existing SIP or SIP awaiting approval is inaccurate
or not current, then, viewing air quality and scope
of emissions with public interest in mind, EPA
should properly evaluate the new information and
may not simply ignore it without reasoned
explanation of its choice.’’ Id. at 967.
60 Id. at 968 (citing Burlington Truck Lines v.
United States, 371 U.S. 156, 168 (1962)).
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Thus, we continue to find that the 2013
base year inventories in the SJV PM2.5
Plan for the 1997 annual PM2.5 NAAQS
satisfy the requirements of CAA section
172(c)(3) and 40 CFR 51.1008 for
purposes of both the Serious area and
the CAA section 189(d) attainment plan
requirements, and to find that the
forecasted inventories provide an
adequate basis for the BACM, RFP, and
the modeled attainment demonstration
analyses in the Plan.
3. Ammonia Precursor Demonstration
Comment 3: CCEJN states that the
EPA must disapprove the ammonia
precursor demonstration based on
considerations outlined in several
specific comments (summarized in
Comments 3.A through 3.D that follow),
but also in several introductory remarks.
In the introductory remarks, the
commenter appears to refer to the
precursor demonstration’s modeled
PM2.5 responses to ammonia reductions
for the 2020 analysis year, some of
which are above the 0.2 mg/m3 EPArecommended contribution threshold
for the 2012 annual PM2.5 NAAQS in the
EPA’s ‘‘PM2.5 Precursor Demonstration
Guidance’’ (‘‘PM2.5 Precursor
Demonstration Guidance’’).61 Based on
these model results, the commenter
asserts that the State tacitly
acknowledges that ammonia
assessments in previous PM2.5 plans,
finding that ammonia does not
contribute significantly to PM2.5 levels
that exceed the 1997 annual PM2.5
NAAQS, were incorrect. The commenter
concludes that these results indicate
that the State should have been
regulating ammonia in the recent past,
and also that the State should err on the
side of caution and regulate ammonia
now. Finally, CCEJN contends that not
regulating ammonia has led to greater
ammonium nitrate PM2.5, thereby
implicating disparate treatment and
disparate impacts, and that the State has
failed to provide necessary assurances
that the policy decision not to regulate
ammonia complies with Title VI.
Response 3: The EPA disagrees with
the commenter’s premise that the
modeled PM2.5 responses for the 2020
analysis year indicate that ammonia
contributed significantly to PM2.5 levels
in the past. Under the EPA’s PM2.5
Precursor Demonstration Guidance, a
response above the recommended
61 ‘‘PM
2.5 Precursor Demonstration Guidance,’’
EPA–454/R–19–004, May 2019, including
memorandum dated May 30, 2019, from Scott
Mathias, Acting Director, Air Quality Policy
Division and Richard Wayland, Director, Air
Quality Assessment Division, Office of Air Quality
Planning and Standards (OAQPS), EPA, to Regional
Air Division Directors, Regions 1–10, EPA.
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86589
contribution threshold indicates a
‘‘contribution,’’ but additional
information can be considered in
determining whether that response
‘‘contributes significantly.’’ 62 Such
information may include, but is not
limited to, the amount by which the
threshold is exceeded, studies to
evaluate specific atmospheric chemistry
in the area, trends in ambient speciation
data and precursor emissions,63 and the
general facts and circumstances of the
nonattainment area.64 In concluding
that ammonia does not contribute
significantly, the State considered
model responses for the 2024 analysis
year in addition to 2020, as well as other
additional information, as summarized
in the EPA’s February 2020 Precursor
Technical Support Document.65 We do
not believe that viewing modeled
responses to ammonia for specific years
in isolation or out of context is an
adequate method for determining
whether a precursor contributes
significantly to PM2.5 levels.
Additionally, the EPA does not agree
that prior precursor assessments should
be considered erroneous based on the
analysis in a newer plan, particularly
when the more recent plan uses
different criteria for assessing precursor
significance. Previous plans for the 1997
annual PM2.5 NAAQS in the San Joaquin
Valley, like the ones mentioned by the
commenter, predated the 2016 ‘‘Fine
Particulate Matter National Ambient Air
Quality Standards: State
Implementation Plan Requirements’’
(‘‘PM2.5 SIP Requirements Rule’’) 66 and
the 2019 PM2.5 Precursor Demonstration
Guidance; therefore, they did not assess
a modeled ammonia response relative to
a contribution threshold but rather
relied on the conclusions from modeling
performed at the time and from past
studies indicating that ammonium
nitrate PM2.5 is far more responsive to
NOX reductions than to ammonia
reductions. Following promulgation of
the PM2.5 SIP Requirements Rule, the
EPA now requires that each precursor
be evaluated individually by comparing
modeled responses to the contribution
threshold and considering additional
information.67 The State conducted its
precursor analysis for the SJV PM2.5
62 PM
2.5 Precursor Demonstration Guidance, pp.
17–19.
63 Id.
64 Id. at 14; 40 CFR 51.1006(a)(1)(ii).
65 ‘‘Technical Support Document, EPA Evaluation
of PM2.5 Precursor Demonstration, San Joaquin
Valley PM2.5 Plan for the 2006 PM2.5 NAAQS,’’
February 2020.
66 81 FR 58010 (August 24, 2016).
67 40 CFR 51.1006; EPA’s PM
2.5 Precursor
Demonstration Guidance.
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Plan in accordance with these
requirements.
Regarding CCEJN’s Title VI-related
concerns, we address the comments
regarding Title VI in Responses 1.A, 1.B,
5, and 7, which rely on supporting
information discussed in Responses 3.A,
3.B.1 through 3.B.4, 3.C, and 3.D.
Comment 3.A: CCEJN’s first specific
stated concern with the precursor
demonstration is that the State’s
conclusion that the San Joaquin Valley
is NOX-limited relies on low NOX
estimates based on soil NOX emissions
that are biased low. The commenter
asserts that ‘‘. . .the state’s estimates of
soil NOX emissions are on the extreme
low-end of those reported in the
academic literature, and the state has
acknowledged that it is unsure how
much NOX is actually emitted from soil
in the Valley.’’ The commenter asserts
that the State’s only rationale for
maintaining the current estimate is that
it will take time to develop a new
estimate, even though including
anthropogenic soil NOX emissions has
been a longstanding request by Valley
advocates.
Additionally, CCEJN asserts that
‘‘[t]he state’s reliance on very low
estimates of soil NOX emissions is
contrary to the presumption that
precursors should be regulated and to
the overall ‘preventative’ and
‘precautionary’ tenor of the Act.’’ The
commenter asserts that even if there was
not sufficient time to fully evaluate the
scientific literature, a key question is
what assumptions the State should rely
on in the interim. The commenter
proposes that the State should base its
decision of whether to regulate
ammonia on a median reasonable
estimate of soil NOX emissions, if not
the high-end estimate.
Response 3.A: We do not agree that
the information provided by the
commenter on soil NOX emissions
undermines the State’s conclusion that
PM2.5 formation in the San Joaquin
Valley is NOX-limited (i.e., much more
sensitive to NOX emissions reductions
than to ammonia emissions reductions).
Three lines of evidence support the
EPA’s agreement with the State’s
conclusion. First, at this time, it is not
clear that soil NOX emissions estimates
are largely underestimated as the
commenter suggests. Second, ammonia
emissions are likely underestimated and
so the response to an ammonia
reduction is likely overestimated in the
modeling. Third, ambient measurements
strongly suggest that PM2.5
concentrations would respond relatively
little to ammonia emissions reductions.
We discuss each of these lines of
evidence in the paragraphs that follow.
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We do not dispute that increasing
NOX emissions in the model would be
expected to decrease the modeled
amount of ammonia relative to NOX and
increase the modeled sensitivity of
PM2.5 concentrations to ammonia
reductions. However, as discussed in
detail in Response 2.A, further
investigation is needed and merited
regarding whether soil NOX emissions
are underestimated or the magnitude of
such underestimation. The magnitude of
the difference, if any, could have an
important effect on whether the model
responses to ammonia reductions would
be above the contribution threshold.
Additionally, even if it is determined
that soil NOX emissions are
underestimated, proper updating of the
model emissions inventory to address
the relative abundance of ammonia and
NOX could require updates to both the
NOX and ammonia emissions
inventories, and there is ample evidence
that ammonia emissions are
underestimated. Furthermore,
independent of any emissions estimates
or modeling, evidence from ambient
measurements imply that PM2.5
concentrations would respond very
little to ammonia reductions, and that
the model responses in the precursor
demonstration may be overestimated, as
discussed further in the remainder of
this response. Thus, the EPA disagrees
with the commenter’s assertions that the
State’s conclusion that the San Joaquin
Valley is NOX-limited (in the sense that
it is much more sensitive to NOX
reductions than to ammonia reductions)
is based on biased soil NOX emissions
estimates that compel the EPA to
disapprove the ammonia precursor
demonstration.
A second line of evidence is that
multiple studies have suggested that
ammonia emissions are underestimated
in the San Joaquin Valley. These studies
reached this conclusion by comparing
ambient measurements and satellite
retrievals to model results that
incorporate estimates of ammonia
emissions, and by comparing
monitoring or modeling results to what
would be expected based on the size(s)
of the ammonia and NOX emissions
inventories. For example, in a summary
report for the CalNex air quality study,
the authors concluded based on direct
measurements of ammonia emissions
flux that ‘‘[p]reliminary results indicate
that within the San Joaquin Valley,
[ammonia] emissions could be
underestimated in inventories by about
a factor of three.’’ 68 This finding was
68 Parrish, D. (2014), Synthesis of Policy Relevant
Findings from the CalNex 2010 Field Study, Final
Report to the Research Division of the California Air
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confirmed in later modeling using
monitored data from the DISCOVER–AQ
field study.69 Other studies identified in
a literature search also suggest that
ammonia emissions are underestimated,
as discussed in the remainder of this
response. If higher ammonia emissions
were used in the modeling to correct the
underestimation, then modeled
ammonia would be more abundant
relative to nitrate, and particulate nitrate
formation would be more NOX-limited.
Thus, the modeled response to ammonia
reductions would be lower than
reported in the precursor demonstration
in the SJV PM2.5 Plan, and below the
contribution threshold.
A literature search conducted by the
EPA found ample evidence that
ammonia emissions may be
underestimated in the San Joaquin
Valley.70 Most studies compared air
quality model results with satellite
retrievals; a few compared model results
to measurements from aircraft. All of the
studies reviewed concluded that
ammonia emissions are underestimated
by a factor of two to five. A factor of two
is greater than the 20–51 percent
increase in total NOX emissions
estimated by Almaraz et al. (2018) and
would more than offset the effect of an
increase in soil NOX on the sensitivity
of PM2.5 concentrations to ammonia
reductions. These studies collectively
suggest that ammonia emissions are
underestimated in the San Joaquin
Valley. In turn, that implies that model
estimates of the sensitivity in the
precursor demonstration may be
overestimated.
Note that such an underestimate does
not imply that the emissions inventories
in the SJV PM2.5 Plan do not meet the
requirements of CAA section 172(c)(3);
rather it reflects that more work is
needed to continue to improve ammonia
emissions estimates. Studies may
deduce that there is underestimation
using a ‘‘top down’’ approach relying on
ambient measurements or satellite
observations; the measurements reflect
the atmospheric sum of the contribution
of many sources, possibly over an
extended area. On the other hand, an
emissions inventory developed for
regulatory purposes is typically a
‘‘bottom-up’’ estimate, derived from
Resources Board, 2014, p. 63; available at https://
csl.noaa.gov/projects/calnex/synthesisreport.pdf.
69 Kelly, J.T. et al. (2018), Modeling NH NO over
4
3
the San Joaquin Valley during the 2013 DISCOVER–
AQ campaign, Journal of Geophysical Research:
Atmospheres, 123, 4727–4745, doi:10.1029/
2018JD028290.
70 Memorandum dated October 12, 2023, from
Scott Bohning, EPA Region IX, to Docket EPA–R09–
OAR–2023–0263, Subject: ‘‘Literature search finds
evidence that ammonia emissions are
underestimated.’’
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compiling an inventory of stationary,
area, mobile, and biogenic sources, with
their associated emissions factors and
activity rates. The emissions inventory
is based on detailed knowledge and
measurements of specific source types
under particular conditions. It is
impractical to measure every source
under all environmental conditions or
under all possible variations, and to
know the exact mix of source types and
of management practices in place. Thus,
the emissions inventory depends on the
basic assumption that information
compiled for the subset of sources that
it is practical to measure can be
generalized to the full population of
sources in an area. Characterizing
ammonia emissions from the bottom up
requires spatially and temporally
resolved data, such as detailed farming
practices including irrigation and
fertilizer application, and how they
affect emissions, which may vary
depending on multiple factors. Such
detailed data may not be available
except at an enormous, impractical cost.
A bottom-up emissions inventory may
use the best available data and
techniques, yet not match estimates
made via top-down approaches. The
discrepancy between the estimates from
top-down and bottom-up approaches
indicates the need for further research to
better characterize the specific source
types that contribute to the total.
In 2021, CARB reported comparisons
between its own model predictions of
ammonia to ambient data.71 The SJV
PM2.5 Plan did not include an
evaluation of model performance for
ammonia per se (just for particulate
ammonium), but in a supplemental
transmittal, CARB described the results
of two analyses confirming the likely
underestimation of ammonia. CARB
compared CMAQ model predictions of
ammonia with the 2013 DISCOVER–
AQ 72 aircraft measurements and found
that near-ground ammonia was
underpredicted by 50 percent at Fresno
and 200 percent at Porterville. CARB
also compared 2017 satellite
observations of ammonia from the
Infrared Atmospheric Sounding
Interferometer to CMAQ model
predictions and found that modeled
ammonia concentrations were half of
the magnitude of the satellite retrievals
at some locations, and that the modeled
average in the San Joaquin Valley was
71 Email dated April 26, 2021, from Laura Carr,
CARB, to Scott Bohning, EPA Region IX, Subject:
‘‘RE: Ammonia update,’’ with attachment
‘‘Ammonia in San Joaquin Valley’’.
72 DISCOVER–AQ: ‘‘Deriving Information on
Surface conditions from COlumn and VERtically
Resolved Observations Relevant to Air Quality,’’
https://science.nasa.gov/mission/discover-aq.
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about 25 percent less than observed.
CARB also noted that underprediction
of ammonia would result in the
modeled PM2.5 response to ammonia
reductions being overpredicted.
Finally, a third line of evidence
supports the conclusion that PM2.5 in
the San Joaquin Valley is relatively
insensitive to ammonia reductions.
Evidence from ambient data is
especially strong since it is independent
of uncertainties in the emissions
estimates and the modeling exercises.
Appendix G (‘‘Precursor
Demonstration’’) of the 2018 PM2.5 Plan
and Appendix C (‘‘Weight of Evidence
Analysis’’) of the CARB Staff Report on
the 2018 PM2.5 Plan 73 describe previous
research in support of the claim that
ammonium nitrate PM2.5 formation is
NOX-limited rather than ammonialimited. That is, PM2.5 concentrations in
the San Joaquin Valley are expected to
be sensitive to reductions in NOX
emissions but much less sensitive to
reductions in ammonia. Essentially, due
to the abundance of ammonia, even
with ammonia emissions reductions
there would still be enough available
ammonia to combine with NOX (in the
form of nitric acid) to form about the
same amount of particulate ammonium
nitrate. This was the conclusion of
Lurmann et al. (2006) 74 based on
ambient measurements during the
California Regional Particulate Air
Quality Study (CRPAQS), an intensive
field study during winter 2000–2001.
Ammonia was almost always abundant
relative to the amount of nitric acid 75
(derived from NOX and the immediate
precursor to particulate nitrate), so the
authors concluded that ammonium
nitrate formation in the San Joaquin
Valley was NOX-limited. This
conclusion was based on ambient data
collected before the additional 60
percent reduction in NOX emissions that
has occurred in the interim, which
would be expected to have increased the
degree of NOX-limitation (i.e.,
particulate ammonium nitrate formation
would be more limited by, and so more
sensitive to, the amount of NOX).
73 CARB’s ‘‘Staff Report, Review of the San
Joaquin Valley 2018 Plan for the 1997, 2006, and
2012 PM2.5 Standards,’’ release date December 21,
2018.
74 Lurmann et al. (2006) Processes Influencing
Secondary Aerosol Formation in the San Joaquin
Valley during Winter, Journal of the Air & Waste
Management Association, 56(12):1679–1693, doi:
10.1080/10473289.2006.10464573.
75 Nitric acid (HNO ) is formed from NO
3
X
emissions; it combines with ammonium to form
particulate ammonium nitrate. The relative
amounts of nitric acid and ammonium indicate
which is the limiting factor in ammonium nitrate
formation.
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Consistent with CRPAQS, aircraftborne measurements during the more
recent 2013 DISCOVER–AQ 76 study led
CARB to a similar conclusion, based on
the large amount of ‘‘excess ammonia’’.
This is defined as the amount of
measured ammonia left over if all the
nitrate and sulfate present combined
with available ammonia to form
particulate. The CARB December 2018
Staff Report describes this in more
detail,77 and also lists results from
multiple other recent studies with
similar conclusions. Two studies with
chemical modeling,78 79 at temperature
and humidity levels typical for the San
Joaquin Valley and with ammonia and
nitrate concentrations observed during
DISCOVER–AQ, showed that over 90
percent of the nitrate is present as
particulate rather than gas, consistent
with abundance of ammonia and with
low sensitivity to ammonia changes.
Two other studies, one using data from
DISCOVER–AQ 80 and one using data
from the 2010 CalNex field campaign, 81
found measured ammonia to be 50–100
times as abundant as nitric acid,
implying low sensitivity to ammonia
emissions changes.82 In summary, the
76 DISCOVER–AQ: ‘‘Deriving Information on
Surface conditions from COlumn and VERtically
Resolved Observations Relevant to Air Quality,’’
https://science.nasa.gov/mission/discover-aq.
77 CARB, ‘‘Staff Report: Review of the San Joaquin
Valley 2018 Plan for the 1997, 2006, and 2012 PM2.5
Standards,’’ December 21, 2018, Appendix C, 12ff.;
available at https://ww2.arb.ca.gov/resources/
documents/2018-san-joaquin-valley-pm25-plan.
78 Id. at 12 (presenting CARB analysis of ammonia
impacts in the San Joaquin Valley).
79 Prabhakar et al. (2017) Observational
assessment of the role of nocturnal residual-layer
chemistry in determining daytime surface
particulate nitrate concentrations, Atmospheric
Chemistry Physics, 17, 14747–14770. doi:10.5194/
acp-17–14747–2017.
80 Parworth et al. (2017) Wintertime water-soluble
aerosol composition and particle water content in
Fresno, California, Journal of Geophysical Research,
Atmosphere., 122, 3155–3170. doi: 10.1002/
2016JD026173, p. 3165. (noting that ‘‘The average
mixing ratio of NH3 was 49 times greater than HNO3
. . . . These results highlight that NH3 was in
excess, and NH4NO3 [ammonium nitrate] formation
is likely limited by HNO3 availability in Fresno,’’
i.e., about a factor of 50).
81 CalNex, or California Research at the Nexus of
Air Quality and Climate Change, was a NOAAsponsored field study during summer 2010; https://
www.esrl.noaa.gov/csd/projects/calnex/. Markovic
et al., (2014), Measurements and modeling of the
inorganic chemical composition of fine particulate
matter and associated precursor gases in
California’s San Joaquin Valley during CalNex 2010,
Journal of Geophysical Research—Atmospheres,
119, 6853–6866, doi:10.1002/2013JD021408, p.
6863 (noting that ‘‘ . . . the observed NH3 (g)
mixing ratios were elevated . . . the observed HNO3
(g) mixing ratios were 2 orders of magnitude
lower,’’ i.e., about a factor of 100).
82 The CARB December 2018 Staff Report
explains (in Appendix C, p. 14) that NOX is the
limiting pollutant as shown by this relative
abundance of ammonia, but that the expected low
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ambient field study data that the EPA is
aware of is consistent with a conclusion
that PM2.5 concentrations in the Valley
are much more sensitive to NOX
emissions reductions than to ammonia
emissions reductions. This evidence is
independent of the State’s soil NOX
emissions estimate and is an important
basis for the EPA’s determination that
the responses to ammonia reductions for
the 1997 annual PM2.5 NAAQS that are
slightly above the recommended
contribution threshold are likely
overestimated. Thus, the ambient
evidence supports the EPA’s
determination that ammonia does not
contribute significantly to PM2.5 levels
above the 1997 annual PM2.5 NAAQS.
Comment 3.B.1: CCEJN’s second
concern with the precursor
demonstration relates to the State’s
conclusions regarding the level of
ammonia reductions that could be
achieved through potential control
measures. The commenter asserts that
‘‘. . . the state repeatedly uses a lack of
certainty about emission reduction
potential to justify no regulation at all.’’
As an example, they argue that the State
acknowledges that research shows that
ammonia emissions from manure-based
fertilizer can be reduced by 50–90
percent through quick mixing or
injection but that it declines to consider
the measure feasible for synthetic
fertilizers merely because the State does
not know how effective it will be.
Response 3.B.1: We disagree with
CCEJN’s claim that the State relies
primarily on a lack of certainty about
potential emissions reductions to justify
not regulating ammonia in the San
Joaquin Valley. Rather, the State based
its decision not to regulate ammonia for
purposes of meeting the 1997 annual
PM2.5 NAAQS on the technical analyses
it performed indicating that ammonia
does not contribute significantly to
PM2.5 concentrations that exceed the
1997 annual PM2.5 NAAQS.
Where the State identifies
uncertainties about potential ammonia
emissions reductions, it does so in the
context of its controls analysis to
support the ammonia precursor
demonstration, which it conducted at
the request of the EPA and in
accordance with EPA guidance. As
acknowledged by the commenter, under
the PM2.5 SIP Requirements Rule, a state
may submit an optional precursor
demonstration showing that a particular
PM2.5 precursor chemical species does
sensitivity to ammonia reductions does not mean
zero response; the reduction necessarily shifts
nitrate from particulate to gas to maintain chemical
equilibrium. Thus, NOX being the limited pollutant
does not contradict the modeled responses to 30–
70 percent reductions.
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not contribute significantly to PM2.5
levels above the standard in the area.83
If the EPA approves a precursor
demonstration for a particular chemical
species, the state is not required to
control emissions of that precursor from
existing sources in the relevant
attainment plan.84
The EPA’s July 2023 proposal
includes a detailed summary of the
precursor demonstration in the SJV
PM2.5 Plan and supporting March 2023
Ammonia Supplement, and of the EPA’s
evaluation. We will not reiterate all of
the State’s conclusions herein except to
highlight the key finding that modeled
sensitivities for the 1997 annual PM2.5
NAAQS of PM2.5 concentrations to a 30
percent ammonia reduction are
approximately at or below the
contribution threshold used to
determine significance. The PM2.5
Precursor Guidance explains that in
cases where the PM2.5 response to a 30
percent reduction in precursor
emissions is close to the contribution
threshold, the EPA may require air
agencies to identify and evaluate
potential emissions controls in support
of a precursor demonstration that relies
on a sensitivity analysis. The response
of ambient PM2.5 to an actual assessment
of the benefit from potential controls
can be used to determine whether
controlling ammonia would
significantly affect PM2.5 levels. In
accordance with 40 CFR
51.1010(a)(2)(ii), the EPA required the
State to provide an analysis of potential
controls to aid the EPA in its evaluation
of the precursor demonstration. The
State provided such controls analysis in
the March 2023 Ammonia Supplement,
which built upon information
previously provided in the 2018 PM2.5
Plan.
As discussed in our proposal, the
State’s controls analysis included a
review of ammonia emissions
reductions achieved nationwide from
2011 to 2017, an evaluation of the main
ammonia source categories in the San
Joaquin Valley, a summary of existing
control measures in the San Joaquin
Valley that affect ammonia from these
sources, a review of existing control
measures implemented by other air
districts, and an evaluation of additional
mitigation options for ammonia sources
in the Valley.85 Based on the State’s and
District’s analyses, they determined that
significant ammonia emissions
reductions are already being achieved
83 81 FR 58010, 58021 (August 24, 2016); 40 CFR
51.1006 (‘‘Optional PM2.5 precursor
demonstrations’’).
84 40 CFR 51.1006(a)(1)(iii) and 51.1010(a)(2)(ii).
85 88 FR 45276, 45288–45290.
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by measures targeting VOC emissions
and that the ammonia reductions
achievable from additional controls are
well below 30 percent.
In this action, we are finalizing our
determination that the State has
provided adequate support for its
conclusion that available additional
ammonia controls would yield less than
a 30 percent reduction in ammonia
emissions. We are finding that the
District made a convincing case that
significant ammonia reductions have
already been achieved through District
Rule 4570 and that few additional
mitigation measures could provide only
modest further reductions from
confined animal facilities (CAFs), which
account for 58 percent of the total
ammonia inventory. Similarly, the State
has provided support for its assertion
that additional reductions are not
feasible from the fertilizer, composting,
and other smaller source categories
through its analysis of potential
fertilizer controls and information
regarding controls that are already in
place for these source categories. As
discussed in our proposal, we
acknowledge the uncertainty in the
reductions that are currently being
achieved from the fertilizer source
category but are finalizing our
determination that even if ammonia
reductions could be reduced by a very
high percentage, such reductions added
to the potential reductions from CAFs
would amount to less than a 30 percent
reduction in total ammonia emissions.
Given that the State’s modeled
sensitivities of PM2.5 concentrations to a
30 percent ammonia reduction are
approximately at or below the threshold
used for identifying an impact that is
significant for the 1997 annual PM2.5
NAAQS, and that the potential
additional reductions would be well
below 30 percent, the response of PM2.5
to an ammonia reduction of a
percentage smaller than 30 percent
would be below the contribution
threshold, indicating that ammonia does
not contribute significantly to ambient
PM2.5 concentrations for purposes of the
SJV PM2.5 Plan for the 1997 annual
PM2.5 NAAQS. Based on these results,
the State excluded ammonia controls
from the SIP submission. Because the
EPA is finalizing approval of the State’s
precursor demonstration as proposed,
the State is not required to regulate
ammonia for purposes of meeting the
CAA requirements for the 1997 annual
PM2.5 NAAQS.
Regarding the example cited by the
commenter of quickly mixing or
injecting fertilizer into the soil, we do
not disagree that research literature
indicates that quick mixing or injection
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can reduce ammonia emissions from
manure-based fertilizer. The State
acknowledges in the March 2023
Technical Supplement that applying
manure to the soil surface without
incorporation can lead to significant
ammonia emissions and includes an
extensive discussion of the various
methods of incorporation as well as the
related requirements for injection and
incorporation of manure-based fertilizer
in District Rule 4570. We disagree,
however, with the commenter’s
assertions that because the measure is
effective at reducing ammonia from
manure-based fertilizers, the State
should infer a similar magnitude of
effectiveness for synthetic fertilizers.
The studies cited by the commenter
acknowledge uncertainties and
highlight the importance of additional
research to adapt a potential measure to
local conditions.86 For example, Ti et al.
(2019), in a global meta-analysis of
measures to reduce ammonia emissions
from livestock and cropping systems,
found that the effects of fertilizer
application processes are highly
dependent on crop type.87 The paper
further concludes that mitigation needs
to be carefully planned and adapted to
local conditions because ammonia
emissions are dependent on
environmental factors such as weather
and soil conditions, that the
applicability of measures depends
strongly on farm structures, and that
studies examining economic feasibility
and the effects of combinations of
measures are needed.88 The State’s
March 2023 Ammonia Supplement
draws similar conclusions about the
need for additional research to assess
the potential for ammonia emissions
reductions, specifically as they relate to
quick mixing and injection, under
conditions representative of those in the
San Joaquin Valley.89 Given these
uncertainties, we agree with the State’s
conclusion that additional research is
needed and find that the State’s
decision not to assign ammonia
86 Pan, B. et al. (2016). Ammonia volatilization
from synthetic fertilizers and its mitigation
strategies: A global synthesis. Agriculture,
Ecosystems & Environment, Vol. 232, 283–289,
doi:10.1016/j.agee.2016.08.019; Ti, C. et al. (2019).
Potential for mitigating global agricultural ammonia
emission: A meta-analysis. Environmental
Pollution, Vol. 245, 141–148, doi:10.1016/
j.envpol.2018.10.124.
87 Ti et al. (2019) op cit., p. 146. For example, the
paper notes that the effects of fertilizer application
practices on reducing ammonia emissions from
vegetable production are lower than in wheat and
fruit production due in part to the smaller reduction
in ammonia emissions from vegetable fields
associated with more intensive irrigation.
88 Id. at 147.
89 March 2023 Ammonia Supplement, p. 94.
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reductions to such measure at this time
to be reasonable.
In addition to helping to resolve the
uncertainties related to the effectiveness
of mitigation measures, additional
research would also be beneficial for
improving understanding of any
potential disbenefits that may be
specific to the area. The commenter
appears to acknowledge the potential for
disbenefits in a footnote to their
comment, which notes that CCEJN does
not endorse any specific approach for
reducing ammonia emissions, including
quick mixing or injection, and that
‘‘regulation of ammonia emissions
cannot be permitted to exacerbate
degradation of groundwater quality.’’
These expressed concerns about the
potential for adverse effects on water
quality seem to align with the State’s
position that more research is needed.
Such research may also inform other
important considerations, such as the
effects on greenhouse gas emissions.
Comment 3.B.2: CCEJN asserts that
the State’s evaluation of emissions from
fertilizers is limited in that it is
seemingly based on just two studies,
and does not consider additional
mitigation options identified in the
literature such as using non-urea based
fertilizers; using controlled release
fertilizers; using fertilizers with
nitrification inhibitors; irrigating
immediately after fertilizer placement;
or adding amendments to fertilizers,
such as zeolite, pyrite, or organic acids.
The commenter also points to a study
on the field of precision agriculture as
a resource on mechanisms to minimize
fertilizer use,90 as well as two studies
examining how modeling can be used to
predict ammonia volatilization,
claiming that such studies undermine
the State’s position that emissions
reductions cannot be calculated.91
Response 3.B.2: We disagree with
CCEJN’s characterization of the State’s
analysis of emissions from fertilizer as
‘‘extremely narrow.’’ We infer that the
commenter is referring to the State’s
analyses for synthetic fertilizer
specifically, based on the numerous
studies cited in the State’s discussion of
90 Association of Equipment Manufacturers, The
Environmental Benefits of Precision Agriculture in
the United States, https://newsroom.aem.org/
download/977839/environmentalbenefitsof
precisionagriculture-2.pdf.
91 Gurung, R.B. et al. (2021) Modeling ammonia
volatilization from urea application to agricultural
soils in the DayCent model. Nutr Cycl Agroecosyst,
119, 259–273. doi:10.1007/s10705–021–10122–z;
Yang, Y. et al. (2022) Comprehensive quantification
of global cropland ammonia emissions and
potential abatement. Science of The Total
Environment, 812, 151450, doi:10.1016/
j.scitotenv.2021.151450.
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86593
manure application-related measures,92
and the commenter’s assertion that the
State’s evaluation of fertilizers is
seemingly based on the findings from
just two studies and that Table 13 of the
March 2023 Ammonia Supplement lists
references for Guthrie et al. (2018) 93 and
Eory et al. (2016) only.94 However, we
note that both Guthrie et al. (2018) and
Eory et al. (2016) are compilation
studies covering a range of mitigation
options for organic and synthetic
fertilizer application and that the State’s
March 2023 Ammonia Supplement cites
numerous studies in addition to these
two compilation studies. Furthermore,
the State turned to the research
literature only after reviewing how other
California State agencies are engaged in
fertilizer use and attempting to identify
any existing rules or regulations in the
nation controlling ammonia emissions
from this source category.
Regarding the additional mitigation
options identified by CCEJN, we
appreciate that the commenter raises
these potential strategies. We
acknowledge the studies cited by the
commenter finding that implementation
of some of these strategies may help
minimize ammonia emissions from
agricultural systems around the globe.
We encourage CARB and the District to
keep abreast of research examining
mitigation options for minimizing
ammonia emissions from fertilizer
application in support of future policy
and management decisions, particularly
as they may relate to reducing PM2.5
exposure in the San Joaquin Valley.
However, as discussed in the following
paragraphs, in light of the absence of
any SIP-approved requirements
elsewhere in the nation, the regulations
adopted by other California State
agencies to control fertilizer application,
and the uncertainties discussed in the
studies cited by CARB and the
commenters, the EPA continues to agree
with the State’s overall conclusions that
more research is needed on potential
mitigation measures to reduce ammonia
emissions from fertilizer application in
the San Joaquin Valley. We also agree
that based on the information currently
available, the additional reductions
achievable are sufficiently low that the
PM2.5 response to such reduction would
92 E.g., see March 2023 Ammonia Supplement pp.
74–75.
93 Guthrie, S. et al. (2018). Impact of ammonia
emissions from agriculture on biodiversity: An
evidence synthesis. Rand Europe, The Royal
Society. https://www.rand.org/pubs/research_
reports/RR2695.html.
94 Eory, V. et al. (2016) ClimateXChange, On-farm
technologies for the reduction of greenhouse gas
emissions in Scotland. https://
www.climatexchange.org.uk/media/1927/on-farm_
technology_report.pdf.
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be below the contribution threshold,
indicating that ammonia does not
contribute significantly to ambient
PM2.5 concentrations for purposes of the
SJV PM2.5 Plan for the 1997 annual
PM2.5 NAAQS. As we emphasized in
our proposal, this finding is specific to
the facts and circumstances of this
particular plan and does not predetermine the outcome of significance
determinations of precursors in the
future.
In the March 2023 Ammonia
Supplement, the State describes its
efforts to identify any SIP-approved
requirements limiting ammonia
emissions from fertilizers that are being
implemented in any other areas of the
United States and explains that it has
not identified any rules or regulations
being implemented elsewhere. Thus, it
describes regulations in place adopted
by other California State agencies to
control fertilizer application and its
review of research studies examining
techniques for reducing ammonia
emissions from synthetic fertilizer
application.
The State describes in Appendix C
(‘‘Stationary Source Control Measure
Analyses’’) of the 2018 PM2.5 Plan and
in the March 2023 Ammonia
Supplement the various State agencies
responsible for ensuring
environmentally safe use of fertilizer
material. It describes requirements for
commercial irrigated lands in the San
Joaquin Valley to prepare a farm
management plan (including an
irrigation nitrogen management plan)
that complies with waste discharge
requirements in accordance with the
Central Valley Irrigated Lands
Regulatory Program established by the
California State Water Resources
Control Board. The nitrogen
management plan is designed to ensure
that the amount of nitrogen applied to
agricultural lands is in reasonable
balance with the needs of crops that are
being grown. The State explains that the
‘‘4 R’s’’ of nitrogen management (‘‘Right
source’’ of nitrogen at the ‘‘right rate,’’
‘‘right time,’’ and ‘‘right place’’) 95 serve
as guiding nitrogen efficiencies
principles that growers are
recommended to follow when
developing their management plans,
and that growers are required to employ
enhanced strategies if it is determined
that they are not optimizing fertilizer
use, as determined by the fraction of
nitrogen applied to nitrogen used.
Next, CARB discusses measures
identified in the literature for reducing
ammonia emissions from fertilizer
application, which include optimizing
95 March
2023 Ammonia Supplement, p. 92.
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fertilizer use, adding a urease inhibitor,
mixing and injecting fertilizer into the
soil quickly, and applying fertilizer
during optimal weather conditions.
Based on its review, the State finds that
several of the strategies align with the 4
R’s of nitrogen management but that
more research is needed to determine
the feasibility and effectiveness of such
strategies in California due to the
unique climate conditions and farming
practices in the San Joaquin Valley, and
to explore any potential adverse
consequences. CARB cites studies
linking weather conditions with
ammonia emissions,96 and states that it
is unclear which environmental factors
are the most important for different
fertilizer types.
As discussed in Response 3.B.1, the
studies cited by CCEJN similarly
highlight the need for additional
research to examine how the potential
for ammonia emissions reductions
varies with local conditions. These
studies largely focused on the United
Kingdom or were global in scale and
none of them appear to address
mitigation potentials in the western
United States or San Joaquin Valley
specifically. Thus, none of the studies
reflect climate conditions or farming
practices in the San Joaquin Valley, and
likely also do not reflect efficiencies
already achieved through local
regulations in the Valley. Furthermore,
several of the studies suggest that some
of the measures have already been
adopted in many areas, adding to the
uncertainty about whether and where
there are opportunities for significant
reductions in ammonia. For example,
Pan et al. (2016), notes that ‘‘[e]nhanced
efficiency fertilizers have been widely
adopted to minimize N[itrogen] loss,
including NH3 volatilization from
agricultural systems.’’ 97 Similarly, Gu et
al. (2023), in a study examining the
potential to mitigate nitrogen pollution
from global cropland, concluded that
the largest reduction of reactive nitrogen
input and losses available were in East
and South Asia and Southeast Asia,
which they attribute to an overuse of
fertilizer in those areas.98 They
calculated a much lower reduction
potential in the European Union,
96 Venterea, R.T. et al. (2012) Challenges and
opportunities for mitigating nitrous oxide emissions
from fertilized cropping systems. Frontiers in
Ecology and the Environment, 10:10, 562–570.
doi:10.1890/120062; Grahmann, K., et al. (2013)
Nitrogen use efficiency and optimization of
nitrogen fertilization in conservation agriculture.
Cabi Reviews, 8:053. doi:10.1079/
PAVSNNR20138053.
97 Pan et al. (2016) op. cit., p. 288.
98 Gu, B. et al. (2023) Cost-effective mitigation of
nitrogen pollution from global croplands. Nature,
Vol. 613, pp. 77–84.
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Australia, and North America, where
they concluded that nitrogen use in
croplands is ‘‘closer to the estimated
optimal level.’’
In addition to the uncertainty in
emissions reduction potentials, we note
that studies suggest that one of the five
mitigation options identified by CCEJN,
using fertilizers with nitrification
inhibitors, may lead to an increase in
ammonia emissions. For example, Pan
et al. (2016) noted that ‘‘[a]lthough
nitrification inhibitors are designed to
target N2O emissions, the use of these
inhibitors may prolong the retention of
NH4 in the soil resulting in [ammonia]
volatilization (Kim et al., 2012; Lam et
al., 2016; Ni et al., 2014).’’ 99 Pan et al.
(2016) concluded that nitrification
inhibitors increase ammonia
volatilization by 38.0 percent.100
Similarly, Ti et al. (2019) found that
nitrification inhibitors increased
ammonia emissions by 42.6 percent,101
whereas Newell Price et al. (2011) found
that ‘‘[ammonia] emissions to air and
ammonium/nitrite losses to water may
be increased by a small amount.’’ 102
While studies specific the San Joaquin
Valley may show different results, based
on the studies cited by the commenter,
the research currently available does not
indicate that use of fertilizers with
nitrification inhibitors would reduce
ammonia emissions in the San Joaquin
Valley.
The studies that CCEJN points to on
precision agriculture also note wide
adoption of such practices while
acknowledging some potential for
additional environmental benefits. For
example, in a 2021 report on the
benefits of precision agriculture in the
United States, the Association of
Equipment Manufacturers discusses
environmental improvements that have
already been achieved through adoption
of precision agriculture technologies.103
Whitmore (2019) notes that larger farms
have been quicker to adopt precision
agriculture techniques due to greater
resources,104 and Lowenberg-Deboer
99 Pan
et al. (2016) op. cit., p. 284.
at p. 286.
101 Ti et al. (2019) op. cit., p. 143.
102 J. Newell Price, et al., (2011) An inventory of
mitigation methods and guide to their effects on
diffuse water pollution, greenhouse gas emissions
and ammonia emissions from agriculture (Defra
Project WQ0106). https://randd.defra.gov.uk/
Document.aspx?Document=MitigationMethodsUser
GuideDecember2011FINAL.pdf, p. 52.
103 Association of Equipment Manufacturers, The
Environmental Benefits of Precision Agriculture in
the United States, https://newsroom.aem.org/
download/977839/environmentalbenefits
ofprecisionagriculture-2.pdf.
104 Whitmore J. (2019) Precision Farming Comes
into Its Own, Mich. St. Univ., https://www.canr.
msu.edu/news/precision-farming-comes-into-itsown.
100 Id.
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and Erickson (2019) note that ‘‘[t]he
biggest gap in [precision agriculture]
adoption is for medium and small farms
in the developing world that do not use
motorized mechanization,’’ which they
attribute to cost-effectiveness
challenges.105 Lowenberg-Deboer and
Erickson (2019) also highlight the
perception that adoption of precision
agriculture has been slow, but state that
‘‘[s]ome aspects of [precision
agriculture] were adopted as quickly
and as widely as any technology in
history, while others have lagged behind
for technical and economic reasons.’’ 106
Taken together, the EPA finds that the
studies cited by CCEJN highlight the
uncertainties in the feasibility of the
measures identified in its comment
letter and suggest that more research is
needed to estimate the additional
reductions achievable in the San
Joaquin Valley. Furthermore, while
several studies suggest that there may be
the potential for additional ammonia
reductions from synthetic fertilizer
application, they also indicate that such
potential is not quantifiable with the
information available at this time and
may be lower in the San Joaquin Valley
than in other locations around the globe.
Finally, regarding CCEJN’s comment
about the availability of modeling to
predict ammonia volatilization, we
acknowledge these additional studies 107
identified by the commenter describing
models for estimating ammonia
emissions. However, we disagree with
the commenter that the output from
these models compel certain policy
decisions in the San Joaquin Valley at
this time. Here again the commenter
cites large-scale studies that do not
reflect model performance under
conditions representative of those in the
Valley. Both studies cited by the
commenter note uncertainties due to
crop type, meteorological conditions,
and other factors, suggesting that
research specific to the climate and
farming practices in the Valley is
needed. Furthermore, it is not clear that
the models discussed in the studies are
ripe for application in a regulatory
context. For example, Gurung et al.
(2021) concludes that additional
research is needed before the models
could be used to evaluate policy
decisions for mitigating ammonia
emissions from soils:
In future research, DayCent can also be
used to test ‘‘what if’’ scenarios for
105 Lowenberg-DeBoer, J. and Erickson, B. (2019)
Setting the Record Straight on Precision Agriculture
Adoption, Agronomy J., p. 1565.
106 Id. at 1552.
107 Gurung et al. (2021) op. cit.; Yang et al. (2022)
op. cit.
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identifying best management practices
(BMPs) given variation in the soil and
climatic conditions. These scenarios could
focus on adopting the 4R nutrient
stewardship principles and identifying
regional level BMPs associated with the
addition of urea fertilization. Further model
improvement would also allow for a broader
set of options to be evaluated in support of
policy and management decisions associated
with mitigating of NH3 volatilization from
agricultural soils.
Thus, based on our review, we find
the State’s conclusions that further
research is needed to explore ammonia
reduction potentials in the San Joaquin
Valley to be reasonable. We encourage
the State and District to perform and
keep abreast of research on quantifying
the effects of mitigation measures on
ammonia emissions and their
implications for policy and management
decisions.
Comment 3.B.3: CCEJN asserts that
the State dismisses controls for
fertilizers on the basis that there is no
published literature on control
effectiveness in the San Joaquin Valley
specifically. The commenter contends
that such justification is ‘‘sometimes
absurd’’ and that it cannot be true that
studies specific to the Valley are
necessary to determine that minimizing
the use of fertilizer will decrease
ammonia emissions. The commenter
asserts that ‘‘this bar for effectiveness
makes meaningful regulation
impossible, particularly when the state
disincentivizes research in the Central
Valley by insisting that ammonia need
not be regulated.’’ The commenter
further notes that it is unfortunate that
the State never mentions conducting
any studies in the San Joaquin Valley.
Response 3.B.3: We disagree with
CCEJN that the State claims that studies
specific to the Valley are needed to
discern that reducing fertilizer use will
reduce ammonia emissions. In the 2018
PM2.5 Plan, the State discusses the link
between fertilizer application and both
ammonia emissions and nitrate
contamination in groundwater, and
describes current State regulations
aimed at optimizing fertilizer use to
minimize emissions of ammonia to the
atmosphere.108 Additionally, in its
discussion of optimizing or minimizing
fertilizer use in the 2023 Ammonia
Supplement, the State discuss the ‘‘4
R’s’’ of nitrogen management (i.e.,
‘‘applying the ‘Right source’ of nitrogen
at the ‘Right rate,’ ‘Right time,’ and
‘Right place’ ’’) and that minimizing
fertilizer use is consistent with the right
rate principle. CARB also notes that
Guthrie et al. (2018) describes that
108 2018
minimizing the application of fertilizer
to a level commensurate with optimal
crop production can reduce ammonia
emissions.109 Thus, the State does
acknowledge the potential benefits of
minimizing fertilizer use on ammonia
emissions. Where the State concludes
that additional research is needed is in
the context of how optimal fertilizer use
can be achieved, which it notes is ‘‘not
well described by both Guthrie et al.
(2018) and the publications they
referenced, nor were any specific
regulations identified.’’ Given that some
level of reduction is already being
achieved through existing regulations
and current practices, and the
importance of careful consideration of
environmental factors for optimizing
fertilizer use, we find the State’s
conclusion that additional research
specific to the warm, dry climate
conditions of the San Joaquin Valley is
needed to determine whether additional
strategies could further optimize
fertilizer use and reduce ammonia
emissions to be reasonable.
Regarding CCEJN’s statement that the
State dismisses controls for fertilizers
based on a lack of information on
control effectiveness in the Valley, as
discussed in Responses 3.B.1 and 3.B.2,
studies reviewed by the State, as well as
studies cited by the commenter,
emphasize that strategies to reduce
ammonia emissions are highly
dependent on local environmental
factors and farm structures, and that
more research is needed to examine
these factors, as well as the effects of
combinations of measures. The State
concludes that specific mitigation
strategies identified in the literature,
such as optimizing fertilizer use, are
already being implemented in the San
Joaquin Valley because of regulations
adopted by other California State
agencies and co-benefits such as
reduced cost to farmers. Based on the
literature study findings regarding the
importance of local information and the
need to examine combinations of
measures, the absence of existing rules
or regulations in other areas controlling
ammonia emissions directly, and the
State’s evaluation of the mitigation
strategies already implemented through
regulation by other State agencies, we
maintain that it is reasonable that the
State concludes that more research
specific to the Valley is needed to assess
the feasibility and effectiveness of
additional measures for synthetic
fertilizers.
We also disagree with CCEJN’s
assertions that needing additional
studies specific to the conditions in the
PM2.5 Plan, Appendix C, pp. C–339 to C–
109 March
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Valley makes meaningful regulation
impossible and that the State
disincentivizes research by concluding
ammonia does not need to be regulated.
Contrary to the commenter’s claim that
the State does not discuss any studies
that it is conducting to assess the
effectiveness of ammonia controls in the
Valley, the State does include a
discussion of recent and ongoing and
research in Section 4 of the March 2023
Ammonia Supplement. CARB’s work
includes the development of a mobile
measurement platform equipped with
an ammonia monitor and other
instrumentation to examine ammonia
sources. The State notes that in fall
2018, CARB collaborated with
researchers from the University of
California, Davis to measure ammonia
and other air pollutants near dairies in
the San Joaquin Valley to evaluate the
effectiveness of alternative manure
management practices.110 The State also
mentions additional research to evaluate
emissions from dairies, to use satellite
and remote sensing data to evaluate
ammonia emissions sources across the
Valley, and to identify opportunities to
reduce ammonia and other pollutant
emissions from dairy manure lagoons
specifically. These efforts may inform
future decision-making regarding the
regulation of ammonia in the San
Joaquin Valley.
Moreover, the EPA’s action herein to
approve the precursor demonstration in
the SJV PM2.5 Plan for the 1997 annual
PM2.5 NAAQS does not preclude the
State from adopting controls for
ammonia in the future. As discussed in
our proposal, a consequence of this final
action to approve the State’s ammonia
precursor demonstration is that the
State is not required to implement
BACM/BACT level controls for sources
of ammonia for purposes of the SJV
PM2.5 Plan for 1997 annual PM2.5
NAAQS. Under 40 CFR 51.1006(b), such
precursor demonstration approval
applies only to the SJV PM2.5 Plan that
is the subject of this final action. For
any new PM2.5 attainment plan that the
State is required to submit in
accordance with 40 CFR 51.1003 for
purposes of any PM2.5 NAAQS, the EPA
may determine that ammonia
contributes significantly to PM2.5 levels
that exceed the NAAQS and that the
State is required to implement controls
for sources of ammonia for purposes of
such attainment plan.
Comment 3.B.4: Regarding the
District’s current rules, CCEJN asserts
that the State assumes that farmers are
already adopting the most efficient
practices (e.g., feeding the most efficient
amount of protein, incorporating
manure quickly) but ‘‘provides little
support for these assumptions, even
though it is well established that
farmers do not always adopt the most
efficient practices.’’ The commenter
proposes that the precursor analysis
should err on maintaining the
presumption that precursors should be
regulated and thereby err on the side of
high estimates of potential effectiveness
and that because the State does not do
so, its analysis is arbitrary and
capricious. The commenter asserts that
the State relies on ‘‘biased
assumptions,’’ assuming low potential
effectiveness from measures not being
implemented, high reductions from
Rule 4570, and that making optional
measures mandatory would have no
impact. The commenter further
contends that if Rule 4570 is effective,
the State should make its most effective
requirements mandatory where feasible
and possibly increase the stringency,
and that the EPA should require the
State to conduct further analysis of the
rule.
Response 3.B.4: We disagree with
CCEJN’s assertions that the State
provides little support for its estimates
of ammonia reductions that have been
achieved by existing regulations and
that the assumptions it makes to arrive
at those estimates are biased. As
discussed in our proposal, the District
discusses in detail in Appendix C of the
2018 PM2.5 Plan how Rule 4570 is
structured, the control menu
requirements for each of the CAF
operations/sources, and research papers
that support its estimates of ammonia
emissions reductions from the
measures.111 As the District explains,
some of the measures in Rule 4570 are
required to be implemented but the rule
also requires that additional measures
be selected from a menu of options. The
menu-based approach was developed to
allow facilities flexibility to select
measures that are the most practical and
effective for their design and
operation.112
For those measures that are required
to be selected from a menu of options,
the District presents its rationale in
Appendix C of the 2018 PM2.5 Plan and
Appendix F of the staff report for Rule
4570 for its assumptions about which
measure a farmer will select and the
resulting effects on ammonia
111 2018
110 March
2023 Ammonia Supplement, Figure 5
(showing that dairy cattle account for an estimated
67.2 percent of ammonia emissions from CAFs).
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PM2.5 Plan, Appendix C, pp. C–312 to C–
323.
112 Id.; March 2023 Ammonia Supplement, pp.
25–26.
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emissions.113 The District references
research studies to support many of its
assumptions, and where there is greater
uncertainty about which measures may
be selected or the corresponding
ammonia reductions that can be
achieved, the District explains how its
assumptions are conservative. CCEJN
has not provided any evidence to refute
the District’s analysis or conclusions.
Therefore, based on the information
presented, the EPA believes that the
District relied on its expertise and the
best information available and applied
that information reasonably.
Regarding CCEJN’s statement that the
State should err on the side of high
estimates of potential reductions from
additional measures, given the
uncertainties discussed in Responses
3.B.1 and 3.B.2, we find that the
potential emissions reductions
achievable in the San Joaquin Valley
from many of the measures are not
quantifiable at this time and that the
State drew reasonable conclusions
based on the information it evaluated.
While the EPA appreciates that the
commenter raises additional research
studies not identified by the State in its
analysis, as discussed in Responses
3.B.1 and 3.B.2, we have reviewed the
studies and find that they do not
contradict the State’s conclusions. Thus,
we find that the State’s analysis of
potential ammonia emissions reductions
is neither arbitrary nor capricious.
We also find that CCEJN’s claim that
it is well-established that farmers do not
adopt the most efficient practices is not
well supported. To back this claim, the
commenter cites two studies discussing
the rates of adoption of precision
agriculture technologies.114 However,
these studies do not appear to indicate
any reluctance on the part of farmers to
adopt the most efficient practices. As
discussed in Response 3.B.2, these
papers discuss widespread adoption of
precision agriculture technology while
also acknowledging areas where there
are opportunities for increased
adoption, such as for specific crop types
or farm sizes and for specific precision
agriculture technologies, such as
variable rate technology.115 Where
113 2018 PM
2.5 Plan, Appendix C, pp. C–311 to C–
323; SJVUAPCD, ‘‘Final Draft Staff Report,
Proposed Re-Adoption of Rule 4570 (Confined
Animal Facilities),’’ June 18, 2009, at Appendix F,
‘‘Ammonia Reductions Analysis for Proposed Rule
4570 (Confined Animal Facilities),’’ June 15, 2006
(discussing various assumptions underlying the
District’s calculation of ammonia emissions factors).
114 Whitmore (2019) op. cit.; Lowenberg-DeBoer
and Erickson (2019) op. cit.
115 Variable rate technology refers to the use of
data and automation to optimize application of
fertilizer, soil amendments, seed, or plant
protection chemicals to optimize crop performance,
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adoption has been slower, the studies
point to feasibility constraints and the
need for more research. For example,
Lowenberg-DeBoer and Erickson (2019)
emphasize that precision agriculture has
been widely adopted and that in cases
where technologies have been adopted
at a slower pace, the authors attribute it
to technological and economic
feasibility challenges.116 The study
authors also note that the studies they
reviewed hypothesize that more reliable
decision rules that account for the
effects of moisture, temperature, soil
organic matter, and other factors on
nitrogen response may be needed to
increase variable rate technology
adoption.117 Whitmore (2019) similarly
notes the complexity and high cost of
new equipment as barriers to wider
adoption of precision technology.118
CCEJN does not provide any evidence
related to other measures in its letter or
other measures in the State’s analysis to
support its claim.
Finally, we disagree with CCEJN’s
assertion that if Rule 4570 is effective,
the State must consider making its
optional requirements mandatory. As
discussed earlier in this response, if the
EPA approves a state’s precursor
demonstration showing that a particular
PM2.5 precursor chemical species does
not contribute significantly to PM2.5
levels above the standard in the area,
the state is relieved of the obligation to
control emissions of that precursor from
existing sources in the relevant
attainment plan.
Comment 3.C: Regarding the State’s
reliance on 2024 modeling results for its
precursor analysis, CCEJN asserts that
the State should not have relied on
modeling of 2024, which is after the
2023 attainment deadline, and which
nevertheless shows ammonia
contributions that are above the
contribution threshold. CCEJN further
asserts that the use of 2024 modeling
‘‘violates the Act in three ways.’’
First, the commenter asserts that the
approach ignores the requirement to
demonstrate attainment as expeditiously
as practicable because it does not
consider ammonia reductions that may
have resulted in attainment before 2023.
They note that the State claimed it was
close to attaining in 2020 and that
meaningful reductions in ammonia
would have most likely resulted in
attainment earlier (i.e., in 2021 or 2022).
Second, the commenter notes that the
State relies not only on a future year but
save time and money, and reduce environmental
impacts.
116 Lowenberg-DeBoer and Erickson (2019) op.
cit., p. 1552.
117 Id. at 1564–1565.
118 Whitmore (2019) op. cit.
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a year after the attainment deadline.
Because NOX emissions are expected to
be lower in 2024 than 2023, the
commenter suggests that the impacts of
ammonia reductions would be less in
2024 than in 2023 and that the impacts
of ammonia reductions in 2023 are
unknown. The commenter also claims
that the EPA makes assumptions about
how the State conducted its analysis
and recommends that the EPA seek
clarification from the State about
whether the analysis relied on
emissions projected from baseline (i.e.,
existing) control measures or baseline
measures plus measures committed to
in the plan. If the State did not conduct
the analysis ‘‘with numbers that are
comparable to what are expected in
2023,’’ the commenter contends that the
EPA must require the State to redo the
analysis.
Third, CCEJN asserts that the State’s
model indicating a design value of 12.03
mg/m3 cannot accurately describe 2023
conditions given that 2022 data show a
design value well above 16 mg/m3. They
conclude that the ‘‘EPA’s approval of a
precursor analysis that relies on such
unrealistic modeling is therefore
arbitrary and capricious and contrary to
law.’’
Response 3.C: While the State relied
on 2024 modeled sensitivities of PM2.5
to ammonia reductions, it is important
to note that the EPA also considered the
2023 model responses via a NOX-based
interpolation between the State’s model
results for 2020 and 2024. The highest
estimated response was at the Hanford
site, 0.26 mg/m3 for 2024 and 0.27 mg/
m3 for 2023, and did not change the
EPA’s conclusions regarding the
ammonia precursor demonstration.119
In determining that ammonia does not
contribute significantly in the San
Joaquin Valley despite the Hanford
response being above the 0.25 mg/m3
contribution threshold that the State
derived for the 1997 annual PM2.5
NAAQS, we continue to rely on the
abundant ambient evidence of excess
ammonia relative to NOX. This evidence
includes evidence specific to the
Hanford area, where mobile laboratory
observations during the DISCOVER–AQ
study showed ambient concentrations of
ammonia that were approximately five
times higher than those that were
modeled.120 These factors led the EPA
to conclude that the model responses
were likely overestimated and did not
represent a significant contribution of
ammonia to PM2.5 levels.
We further disagree with the
commenter’s assertion that the State’s
119 88
FR 45276, 45293, fn. 184.
J.T. et al. (2018), op. cit.
120 Kelly,
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approach ignores the requirement for
expeditious attainment. The CAA
requirement for expeditious attainment
is not directly relevant for evaluating a
precursor demonstration, which is
mainly concerned with whether PM2.5
in the atmosphere is sensitive to
emissions reductions of the precursor.
For that purpose, the PM2.5 Precursor
Demonstration Guidance provides for
the use of modeled sensitivities of PM2.5
to a reduction in precursor emissions
evaluated in the base year or a future
year, noting that there are many
considerations in choosing the
appropriate year to model.121 The key
factor for the State’s use of a future year
was the fact that sizable NOX emissions
reductions were projected to occur over
time and would change the atmospheric
chemistry in the San Joaquin Valley.
The reductions are mainly due to the
existing motor vehicle control program
and would occur independent of any
controls in, or EPA action on, the
Plan.122 The sensitivity of PM2.5
concentrations to ammonia reductions
decreases with decreasing NOX
emissions. Between 2020 and 2024, the
modeled response to a 30 percent
ammonia emissions reduction declines
by 50 percent at the design value
monitoring site, Bakersfield-Planz, from
0.24 mg/m3 down to 0.12 mg/m3. (The
corresponding decline is 37 percent for
the average over all monitoring sites.)
Thus, much of the benefit of ammonia
controls applied in 2020 would be lost
by 2023 and 2024.
With regard to whether ammonia
emissions reductions could have
resulted in earlier attainment, the EPA
used results from the Plan’s attainment
demonstration to assess the effect of a
30 percent ammonia reduction in 2022
and found that it would not have
resulted in attainment in that year.123
We estimated the 2022 design value as
15.4 mg/m3 by using a NOX emissionsbased interpolation between the Plan’s
2018 and 2023 design values, 16.3 and
14.7 mg/m3, respectively.124 Similarly
we estimated the 2022 sensitivity to
ammonia from the State’s modeled
sensitivities for 2020 and 2024.
Applying a 30 percent ammonia
reduction for 2022 resulted in a design
value of 15.2 mg/m3, which is above the
level of the 1997 annual PM2.5 NAAQS
121 PM
2.5
Precursor Demonstration Guidance, p.
36.
122 2018 PM
2.5 Plan, Appendix B. NOX emissions
decrease 27 percent between 2020 and 2024 due to
baseline measures.
123 Spreadsheet ‘‘Estimated 2023 annual PM
2.5
ammonia sensitivity and 2022 DV.xlsx,’’ ‘‘2023 vs.
2024 response to 30% ammonia reduction,’’ EPA
Region IX, October 20, 2023.
124 15 mg/m3 SIP Revision, Appendix K, Table 33.
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(i.e., 15.0 mg/m3). Thus, we conclude
that ammonia emissions reductions
would not have resulted in attainment
before the Plan’s projected 2023
attainment date.
Regarding the use of 2024 modeled
sensitivities in lieu of modeled
sensitivities for 2023, the EPA finds that
our conclusions would be the same for
the purposes of our evaluation of the
precursor demonstration. We estimated
2023 responses to ammonia emissions
reductions by interpolating between the
responses for available 2020 and 2024
modeling; the interpolation used
projected NOX emissions for 2020, 2023,
and 2024 and found the estimated 2023
response to be only 0.01 mg/m3 higher
than in 2024.125 While there are several
differences between 2020 and 2024
modeled emissions for the various PM2.5
precursors and direct PM2.5, the key
difference for assessing the change in
the sensitivity of PM2.5 to ammonia
reductions is NOX emissions levels. The
modeling for 2020 and 2024 represent
PM2.5 design values for the NOX
emissions levels in 2020 and 2024, and
their respective responses to a 30
percent ammonia emissions reduction.
To estimate the PM2.5 response to
ammonia reductions in other years or
for other control scenarios, only the
NOX emissions level is needed. The
estimate does not depend on NOX
emissions differences between 2023 and
2024 calculated for baseline, controlled,
or other scenarios, only on the resulting
2023 emissions level being evaluated.
The commenter states that it is
unclear whether the precursor
demonstration analysis relied on a
baseline emissions inventory, or an
inventory considering the controls in
the plan. While this is not documented
prominently in the submittal materials,
the precursor demonstration modeling
performed by the State used baseline
projections,126 that is, emissions
expected with existing control measures
and without new control measures from
the 2018 PM2.5 Plan or the 15 mg/m3 SIP
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125 Spreadsheet
‘‘Estimated 2023 annual PM2.5
ammonia sensitivity and 2022 DV.xlsx,’’ ‘‘Whether
30% ammonia reduction could attain early,’’ EPA
Region IX, October 20, 2023.
126 2018 PM
2.5 Plan, Appendix K, Section 5.6
‘‘PM2.5 Precursor Sensitivity Analysis’’, p. 70: ‘‘To
evaluate the impact of reducing emissions of
different PM2.5 precursors on PM2.5 DVs, a series of
model sensitivity simulations were performed, for
which anthropogenic emissions of the precursor
species were reduced by a certain percentage from
the baseline emissions;’’ email dated September 19,
2019, from Jeremy Avise, CARB, to Scott Bohning,
EPA Region IX, Subject: ‘‘FW: SJV species
responses,’’ with attachments, in which the
attached tables have titles like ‘‘Difference in
Annual PM2.5 mass and species between the 2024
baseline run and the 30% PM reduction precursor
run.’’
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Revision.127 Notably, the EPA’s
conclusions for the precursor
demonstration do not depend on which
of the two inventories is used. For the
interpolation to 2023, the EPA relied on
controlled NOX emissions levels (150.6
tpd) to estimate the 2023 response to 30
percent reduction to be 0.265 mg/m3
(reported as 0.27 mg/m3). Using baseline
NOX emissions (153.6 tpd), the
estimated 2023 response is 0.275 mg/m3,
which is about 0.01 mg/m3 higher. Thus,
the difference between using the
baseline or controlled emissions for
assessing the sensitivity to ammonia
emissions reductions is negligible.
Finally, the EPA disagrees that a
monitored 2022 design value being
‘‘well above’’ the modeled 2023 design
value invalidates the modeling for
purposes of the precursor
demonstration. As discussed in the
EPA’s modeling TSD for the 2018 PM2.5
Plan,128 the State determined that the
model performance was excellent, and
the EPA found the results to be adequate
for attainment demonstration modeling.
The modeling used a 2013 base year,
i.e., the specific meteorological and
emissions conditions of 2013, not those
of 2022 (nor of the 2018 monitored
value used in scaling the modeling
results from the 2018 PM2.5 Plan). Even
when the modeling itself is valid, the
model-predicted design value can differ
from a recent monitored design value
due to different meteorological
conditions than in 2013 base case,
emissions variability, and atypical
events that affect the monitored value,
but that are not necessarily reflected in
the modeling because they are
inherently unpredictable.129 The greater
uncertainty in the precursor
demonstration, which supports the
EPA’s conclusion in this final action, is
that the modeling seems to
conservatively overestimate the
sensitivity of PM2.5 concentrations to
ammonia reductions compared to what
would be expected based on ambient
127 In comparison to potential modeling of
controlled emissions, the NOX emissions for
projected baseline years 2020 and 2024 are higher,
ammonia would be less abundant relative to NOX,
and the responses to ammonia reductions would be
higher. Relying on baseline rather than controlled
NOX emissions levels was therefore conservative for
purposes of the ammonia precursor demonstration.
128 EPA, ‘‘Technical Support Document, EPA
Evaluation of Air Quality Modeling, San Joaquin
Valley PM2.5 Plan for the 2006 PM2.5 NAAQS,’’
February 2020.
129 The issue of how model predictions may not
match monitor observations despite a wellperforming model, and how that does not in itself
invalidate the precursor demonstration is discussed
in more detail in the EPA’s proposed disapproval
of the 2018 PM2.5 Plan portion addressing the 1997
annual PM2.5 NAAQS. 86 FR 67329, 67335
(November 26, 2021).
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measurements of ammonia and nitrate,
as discussed in Response 3A.
Comment 3.D: CCEJN’s fourth concern
with the precursor analysis is that it
believes that ‘‘[t]he State improperly
adopts a lax contribution threshold of
0.25 mg/m3.’’ The commenter
acknowledges that the State’s approach
of using a 0.25 mg/m3 threshold is
consistent with the EPA’s guidance but
contends that the guidance is arbitrary
and capricious and that the EPA should
reject it in this rulemaking. To support
their assertion, the commenter reasons
that
[t]he result of the state’s approach is that
an area, like the San Joaquin Valley, that is
failing to meet multiple successively rigorous
standards for the same measurement of the
same pollutant, may need to regulate a
precursor only for purposes of the more
rigorous standard. This is a senseless result
because the failure to meet an alreadyoutdated standard only highlights the
necessity of taking all feasible regulatory
steps, including regulating relevant
precursors.
The commenter concludes that there
is no advantage of two distinct
thresholds because the area will need to
apply the lower threshold eventually,
and states that the ‘‘EPA’s failure to
grapple with this arbitrary result means
that it has failed to provide a reasoned
explanation for its guidance, and the
guidance—or at least its application in
this case—is arbitrary and capricious.’’
For areas not meeting both the 1997 and
2012 annual PM2.5 NAAQS, the
commenter proposes that the EPA
should require states to apply the
threshold for the 2012 NAAQS for
purposes of evaluating a precursor
contribution for both NAAQS.
Response 3.D: The EPA disagrees that
the same contribution threshold must be
used regardless of the level of the
NAAQS being examined. The EPA
believes that applying a threshold that
is proportional to the level of the
NAAQS is appropriate and consistent
with the Act; i.e., 0.2 mg/m3 is
appropriate for the 2012 annual PM2.5
NAAQS of 12.0 mg/m3, and 0.25 mg/m3
is appropriate for the 1997 annual PM2.5
NAAQS of 15.0 mg/m3.
The contribution thresholds the EPA
derived in the PM2.5 Precursor
Demonstration Guidance represent a
change in air quality that is statistically
indistinguishable from the inherent
variability in the measured atmospheric
concentrations. A contribution
threshold that is proportional to, or
scales with, the level of the NAAQS
may also be termed a ‘‘relative’’
approach, since the size of the threshold
is relative to the level of the NAAQS.
The contribution thresholds in the PM2.5
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Precursor Demonstration Guidance were
derived from a relative variability
estimate multiplied by the NAAQS level
for the 2006 24-hour PM2.5 NAAQS and
2012 annual PM2.5 NAAQS. Notably, the
PM2.5 Precursor Demonstration
Guidance states: 130
As described in the Technical Basis
Document, the monitoring site variability is
first calculated as a percentage of the
measured PM2.5. Then the median percent
variability from all sites is multiplied by the
level of the NAAQS to get the threshold
concentrations. Therefore, these thresholds
represent a percentage of the 2006 24-hour
NAAQS (35 mg/m3) and the 2012 annual
NAAQS (12 mg/m3). Different thresholds may
be applicable to other levels and/or forms of
the NAAQS (either past or future).
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The Technical Basis Document 131
referred to in the guidance explains that
relative variability (concentration
changes as a fraction of total
concentration) was found to be more
stable than absolute variability
(concentration changes in mg/m3), and
notes that this ‘‘indicates that a central
tendency value for the relative
variability in the DV [design value].
Therefore, a representative value can be
multiplied by the level of that NAAQS
to obtain a value in concentration units
(mg/m3 for PM2.5) that is appropriately
used to characterize variability.’’ 132 The
Technical Basis Document also explains
that the ‘‘relative variability was fairly
consistent across the range of design
values, suggesting a commonality in the
relative variability across a wide range
of geographic regions, chemical regimes,
and baseline air quality levels.’’ 133
Thus, a concentration amount that is
relative, or proportional, to the NAAQS
level is a better basis than a fixed
concentration number for determining
the size of a concentration change that
is within the inherent variability of
monitored concentrations. The
superiority of the relative variability
approach that was the basis of the PM2.5
Precursor Demonstration Guidance
contribution threshold of 0.2 mg/m3 for
the 2012 annual PM2.5 NAAQS makes it
appropriate to scale that value according
to the NAAQS level to arrive at 0.25 mg/
m3 for the 1997 annual PM2.5 NAAQS.
Moreover, the EPA does not agree that
it is arbitrary or contrary to the Act to
130 PM
2.5 Precursor Demonstration Guidance, p.
17, fn. 20.
131 EPA, ‘‘Technical Basis for the EPA’s
Development of the Significant Impact Thresholds
for PM2.5 and Ozone,’’ EPA–454/R–18–001R–18–
001, EPA OAQPS, April 2018, available at https://
www.epa.gov/nsr/significant-impact-levels-ozoneand-fine-particles, https://www.epa.gov/sites/
default/files/2018-04/documents/ozone_pm2.5_
sils_technical_document_final_4-17-18.pdf.
132 Technical Basis Document, p. 26.
133 Id. at 39.
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apply a lower contribution threshold or
to potentially regulate a precursor only
for a more stringent NAAQS—it is
reasonable to expect that achieving
lower PM2.5 concentrations may require
regulation of additional sources of direct
PM2.5 and/or PM2.5 precursors. This is
true even if an area is nonattainment for
both the higher and lower NAAQS and
the EPA will ultimately be applying the
lower contribution threshold for a
subsequent plan to attain the more
stringent NAAQS. Indeed, the PM2.5 SIP
Requirements Rule at 40 CFR 51.1000
defines a precursor demonstration to
mean analyses showing that precursor
emissions do not contribute
significantly to PM2.5 levels that exceed
the relevant PM2.5 standard’’ [emphasis
added]. Applying a lower threshold for
the 1997 annual PM2.5 NAAQS because
the area is in nonattainment for a more
stringent NAAQS could presume that
the modeling and precursor
demonstration in a future plan will
show responses to ammonia reductions
above the lower threshold and that
ammonia will be determined to be
significant, such that ammonia would
need to be controlled. The EPA does not
believe it is appropriate to prejudge the
analyses for a potential future plan.
4. BACM/MSM Demonstration
Comment 4: Regarding the BACM
demonstration, CCEJN notes that the
EPA’s proposed approval does not
address the CAA requirement for most
stringent measures (MSM), asserting
that such analysis is required for a
189(d) plan under 40 CFR
51.1010(c)(2)(i) and (c)(4), and 88 FR
45280, 45297, 45322. The commenter
claims that it appears that the State
acknowledges that the MSM
requirement applies in its submittal and
asserts that the EPA cannot approve the
Plan until it reviews the State’s control
measures under the MSM standard.
The commenter also states that ‘‘[t]he
state’s control measures meet neither
the BACM nor MSM standards.’’ They
note that in previous letters to the EPA
(as summarized in a previous letter
attachment included as Exhibit B),
Valley groups have identified numerous
weaknesses and presented ways the
District could strengthen its regulations.
The commenter asserts that the EPA’s
technical support document
accompanying the proposed action
addresses few of these weaknesses, and
advises that ‘‘[t]o the extent EPA has not
considered whether the suggestions in
the letter constitute BACM or MSM for
purposes of the 1997 annual standard, it
should do so.’’ Specifically, the
commenter notes that ‘‘[o]ne
particularly glaring shortfall in the
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86599
state’s submission is its failure to
contain any analysis of potential control
measures to minimize soil NOX
emissions,’’ and suggests that the EPA
must require the State to analyze the
measures in Exhibit A to CCEJN’s
comment letter (citing control measures
described on pages 5 and 6), including
measures to reduce soil NOX emissions
from fertilized farmlands.
Response 4: We disagree with
CCEJN’s assertion that the EPA must
review the State’s control measures
analysis under the MSM standard. As
outlined in the PM2.5 SIP Requirements
Rule, the CAA requirement for MSM is
tied to a specific trigger in the act—an
extension of the Serious area deadline
under CAA section 188(e).134 The EPA
addressed the relevance of MSM to a
189(d) plan as part of our discussion of
the control strategy for such plan in the
technical support document
accompanying the final rule: 135
In addition to meeting the 5 percent
emission reduction requirement for PM2.5 or
any PM2.5 plan precursor, for any Serious
nonattainment area that fails to attain by the
Serious area attainment date, the state is
required to update its control measures
analysis in the section 189(d) plan. In the
event the area previously had received an
extension of the Serious area attainment date
pursuant to section 188(e), the reevaluation
of control measures referenced in section
51.1010(c)(2) should include a reevaluation
of MSM. (For this reason, section
51.1010(c)(2)(i) refers to the reevaluation of
MSM ‘‘as applicable.’’) If, however, the area
did not previously request and receive an
extension of the Serious area attainment date
under section 188(e), the MSM requirement
does not apply.
Thus, we noted in the summary of the
requirements for Serious PM2.5 areas
that fail to attain in our proposed action
that MSM is applicable only if the EPA
granted an extension of the attainment
date under CAA section 188(e) for the
area for the NAAQS at issue.136
As discussed in our proposal,
California’s Serious area plan for the
1997 PM2.5 NAAQS submitted in 2015
included a request under CAA section
188(e) to extend the attainment date for
the 1997 annual PM2.5 NAAQS by five
years to December 31, 2020.137
However, after considering public
comments, the EPA denied California’s
request for an extension of the
attainment date and subsequently
determined that the area failed to attain
by the December 31, 2015 Serious area
134 81
FR 58010, 58094.
‘‘Response to Comments on the Fine
Particulate Matter National Ambient Air Quality
Standards: State Implementation Plan
Requirements,’’ July 29, 2016.
136 88 FR 45276, 45280, fn. 57.
137 Id. at 45277.
135 EPA,
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attainment date, triggering the
requirement for the 189(d) plan.
Consequently, because the San Joaquin
Valley area did not receive an extension
of the Serious area attainment date
under CAA section 188(e), the MSM
requirement does not apply for purposes
of the 1997 annual PM2.5 NAAQS.
Regarding the commenter’s claim that
the State appears to acknowledge in its
submission that MSM applies, we note
that the State’s controls analysis in the
2018 PM2.5 Plan was developed to
address multiple PM2.5 NAAQS,
including the 2006 PM2.5 NAAQS for
which the State requested an attainment
date extension under CAA section
188(e), triggering the MSM requirement
for those NAAQS. Any assertion by the
State in the SJV PM2.5 Plan that a
particular measure meets the MSM
standard may not necessarily indicate
that the State believes that the
requirement applies for the 1997 annual
PM2.5 NAAQS. Regardless, regarding
CCEJN’s comment that the State’s
control measures do not meet the BACM
or MSM standards, given that the MSM
standard does not apply to the 1997
annual PM2.5 NAAQS, as discussed
earlier in this response, we are
responding only to the commenter’s
assertion regarding BACM.
We also disagree with the
commenter’s assertion that the control
measures in the Plan do not meet the
requirement for BACM for the 1997
annual PM2.5 NAAQS. As discussed in
our proposed rule, in our review of the
State’s and District’s BACM
demonstration, we considered our
evaluation of the State’s and District’s
rules, supporting information provided
in the SJV PM2.5 Plan, and our prior
evaluations of the BACM and MSM
demonstrations in the 2018 PM2.5 Plan
for other PM2.5 NAAQS.138 These prior
evaluations include those to support our
approval of the demonstration for
BACM (including BACT) for the 1997
24-hour PM2.5 NAAQS,139 our approval
of the demonstrations for BACM and
MSM for the 2006 24-hour PM2.5
NAAQS,140 and our proposed
disapproval of the demonstration for
BACM for the 2012 annual PM2.5
NAAQS.141 The EPA’s prior actions for
the 1997 24-hour, 2006 24-hour, and
2012 annual PM2.5 NAAQS are relevant
to our evaluation for this final
rulemaking because the State relied on
a common analysis for each of the PM2.5
standards. The EPA conducted a
thorough analysis of the State’s BACM
138 Id.
at 45305–45306.
FR 4503 (January 28, 2022).
140 85 FR 44192 (July 22, 2020).
141 86 FR 74310 (December 29, 2021).
139 87
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demonstration for purposes of these
prior actions, and updated the analysis
for certain source categories, as
appropriate, for purposes of our
proposed approval of the BACM
demonstration in the SJV PM2.5 Plan for
the 1997 annual PM2.5 NAAQS.
Regarding the EPA’s prior approval of
the BACM demonstration in the 2018
PM2.5 Plan as meeting the CAA
requirements for the 2006 24-hour PM2.5
NAAQS, we note that on September 17,
2020, a group of five environmental,
public health, and community groups
petitioned the Ninth Circuit Court of
Appeals (‘‘Ninth Circuit’’) for review of
the EPA’s final rulemaking approving
the 2018 PM2.5 Plan’s demonstration of
BACM, BACT, and MSM for emissions
sources of direct PM2.5 and NOX for
purposes of the 2006 PM2.5 NAAQS.142
On April 13, 2022, the Ninth Circuit
denied the petitioners’ challenge with
respect to the EPA’s approval of the
Plan’s BACM/MSM demonstration,
upholding such approval for those
NAAQS.
Following approval of the State’s
BACM and MSM demonstrations for the
2006 24-hour PM2.5 NAAQS, on
December 29, 2021, the EPA proposed
to approve portions of the 2018 PM2.5
Plan as meeting the Serious area
requirements for the San Joaquin Valley
for the 2012 annual PM2.5 NAAQS,
including the requirement that the plan
include BACM. However, after
considering public comments, on
October 5, 2022, the EPA proposed to
disapprove portions of the District’s
BACM demonstration, including the
evaluations of ammonia emissions
sources and building heating sources.143
We proposed to disapprove the BACM
demonstration for ammonia sources
based in part on our on proposed
disapproval of the State’s ammonia
precursor analysis for the 2012 annual
PM2.5 NAAQS,144 as well as the State’s
control measure analysis for
ammonia.145 We proposed to
disapprove the BACM demonstration for
building heating sources based on
recent control measure developments
and the time horizon of the 2012 annual
PM2.5 NAAQS portion of the SJV PM2.5
142 See Medical Advocates for Healthy Air v. EPA,
Case No. 20–72780, Dkt. #58–1 (9th Cir., April 13,
2022). The five environmental, public health, and
community organizations, in order of appearance in
the petition, are Medical Advocates for Healthy Air,
National Parks Conservation Association,
Association of Irritated Residents, and Sierra Club.
143 87 FR 60494.
144 Based on our proposed disapproval of the
precursor demonstration for the 2012 annual PM2.5
NAAQS, we proposed to determine that ammonia
remained a regulated precursor for that NAAQS in
the San Joaquin Valley.
145 87 FR 60494, 60509.
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Plan, which raised questions about the
feasibility of implementing additional
controls for such sources for BACM
purposes in the San Joaquin Valley.146
Notably, we did not re-propose action
on any other portions of the State’s and
District’s BACM demonstration that we
had previously proposed to approve.
In response to the EPA’s proposed
disapproval of portions of the BACM
demonstration for the 2012 annual PM2.5
NAAQS, CARB and the District
developed and submitted additional
information to support the ammonia
precursor demonstration and building
heating BACM demonstration for
purposes of meeting the Serious area
and CAA section 189(d) requirements
for the 1997 annual PM2.5 NAAQS. Our
proposal and accompanying ‘‘Technical
Support Document, San Joaquin Valley
PM2.5 Plan Revision for the 1997 Annual
PM2.5 NAAQS,’’ April 2023 (‘‘EPA’s
1997 Annual PM2.5 TSD’’) summarize
the additional information provided by
the State and District and the EPA’s
evaluation. Based on our review, we
determined that the additional
information provided by the State and
District addressed the deficiencies
identified in the proposed disapproval
of the 2018 PM2.5 Plan for the 2012
annual PM2.5 NAAQS as they pertained
to the 1997 annual PM2.5 NAAQS. Thus,
considering our prior approvals of the
State’s and District’s BACM analysis for
the 1997 24-hour PM2.5 NAAQS, BACM
and MSM analysis for the 2006 PM2.5
NAAQS (which was upheld by the
Ninth Circuit), and the supplemental
information provided to update the SJV
PM2.5 Plan based on the latest
information available, we proposed to
approve the BACM demonstration for
the 1997 annual PM2.5 NAAQS.
Regarding the measures in Exhibit B
to CCEJN’s comment letter, the EPA has
reviewed and considered the
recommendations for improvements to
the District’s PM2.5 control strategy as
outlined in the two letters in Exhibit B
sent by environmental groups to the
EPA in 2021 147 and 2022.148 A detailed
summary of our evaluation of the
feasibility of these measures, as well as
numerous others, is provided in
Sections III and IV of the ‘‘EPA Source
Category and Control Measure
Assessment and Reasoned Justification
146 Id.
at 60511–60512.
dated October 22, 2021, from
environmental organizations to Michael S. Regan,
Administrator, EPA, Subject: ‘‘Meeting Request to
Discuss PM–2.5 Crisis in the San Joaquin Valley.’’
148 Letter dated May 18, 2022, from
environmental organizations to Michael S. Regan,
Administrator, Environmental Protection Agency,
Subject: ‘‘Meeting Request to Discuss PM–2.5 Crisis
in the San Joaquin Valley.’’
147 Letter
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Technical Support Document’’
(‘‘Control Measure Assessment
TSD’’) 149 accompanying our proposed
action to promulgate a federal
implementation plan for contingency
measures for the 1997 annual PM2.5
NAAQS, the 2006 24-hour PM2.5
NAAQS, and the 2012 annual PM2.5
NAAQS.150 The EPA determined that
the recommended measures are either
not technologically feasible or not
economically feasible within the two
year timeframe for implementation as
contingency measures discussed in the
EPA’s draft guidance.151 Given that by
statute, contingency measures are
additional requirements that go beyond
attainment planning requirements, and
the shorter timeframe of the attainment
plan for the 1997 annual PM2.5 NAAQS
(i.e., by December 31, 2023), we
similarly conclude that these measures
are not feasible for purposes of the
BACM requirement for the SJV PM2.5
Plan for the 1997 annual PM2.5 NAAQS.
Lastly, we disagree with CCEJN’s
assertion that the EPA must require the
State to analyze the control measures for
soil NOX emissions outlined in Exhibit
A in order to approve the BACM
demonstration for the 1997 annual PM2.5
NAAQS. The EPA previously addressed
the issues of soil NOX emissions and of
analyzing potential controls for such
emissions in the context of the 2018
PM2.5 Plan in the EPA’s ‘‘Response to
Comments Document for the EPA’s
Final Action on the San Joaquin Valley
Serious Area Plan for the 2006 PM2.5
NAAQS,’’ June 2020 (‘‘EPA’s 2020
Response to Comments’’).152 More
recently, the EPA also addressed the
issue of soil NOX emissions from the use
of fertilizers and pesticides in the
context of our final rulemaking
approving CARB’s submission of
emissions inventories for VOC and NOX
for the 2015 ozone NAAQS for areas in
California (‘‘2015 Ozone Inventory Final
Rule’’).153
In both the EPA’s 2020 Response to
Comments and the 2015 Ozone
Inventory Final Rule, the EPA
149 EPA Region IX, ‘‘EPA Source Category and
Control Measure Assessment and Reasoned
Justification Technical Support Document,
Proposed Contingency Measures Federal
Implementation Plan for the Fine Particulate Matter
Standards for San Joaquin Valley, California,’’ July
2023.
150 88 FR 53431 (August 8, 2023).
151 EPA, Office of Air Quality Planning and
Standards, Air Quality Policy Division, ‘‘DRAFT:
Guidance on the Preparation of State
Implementation Plan Provisions that Address the
Nonattainment Area Contingency Measure
Requirements for Ozone and Particulate Matter’’
(‘‘Draft Guidance’’), March 16, 2023, p. 41.
152 EPA’s 2020 Response to Comments, pp. 148–
156, Comments and responses 6.P–1 and 6.P–2.
153 87 FR 59015 (September 29, 2022).
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acknowledged the studies cited by
commenters finding that soil NOX
emissions from fertilizer and pesticide
use contribute to atmospheric NOX
levels in California.154 Particularly, the
EPA acknowledged the growing body of
research surrounding the identification
and quantification of soil NOX
emissions from fertilizer application in
agricultural soils. However, in light of
the uncertainties and disagreements
among the studies regarding the
contribution of fertilized cropland soils
to NOX emissions in California, the EPA
found that CARB’s emissions
inventories met the applicable
requirements of the CAA
notwithstanding the absence of soil NOX
emissions from fertilizer or pesticide
use.155 Furthermore, for purposes of our
final action on the San Joaquin Valley
Serious Area Plan for the 2006 PM2.5
NAAQS, we determined that there was
not sufficient information available to
require a controls evaluation for soil
NOX emissions for purposes of the
BACM analysis for those NAAQS.156
Upon reviewing the studies cited by
CCEJN in its comment letter, we
similarly find that the information
provided is not sufficient to compel a
revision to the emissions inventories in
the SJV PM2.5 Plan for the 1997 annual
PM2.5 NAAQS, given the large
uncertainties in the emissions estimates.
As discussed in Response 2.A, the
magnitude of soil NOX emissions varies
based on temperature; agricultural
practices, such as the timing and
amount of fertilizer application and
irrigation; crop type; and other factors.
Additionally, soil NOX is not directly
emitted and involves numerous natural
emissions sources and processes. Thus,
soil NOX emissions are inherently
difficult to estimate and model.
Likewise, given that the production of
NOX in the soil is complex, it may also
be challenging to estimate the effects of
potential controls. Due to the
complexity of estimating soil NOX
emissions, the partially natural source
of the emissions, and the uncertainties
in the effectiveness of potential control
measures, the EPA concludes that there
is not sufficient information available at
this time to warrant an evaluation of
potential controls for soil NOX
emissions in the San Joaquin Valley for
purposes of the BACM analysis for the
1997 annual PM2.5 NAAQS. We
encourage CARB and the District to
continue their ongoing efforts to resolve
the uncertainties in soil NOX emissions
154 Id.
at 59018.
at 59018–59020.
156 EPA’s 2020 Response to Comments, p. 156.
155 Id.
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and examine any implications for air
quality modeling and planning.
5. Public Process
Comment 5: CCEJN asserts that the
EPA must disapprove portions of the
attainment plan for the 1997 annual
PM2.5 NAAQS because the State did not
provide public notice and the
opportunity to comment on portions of
the Plan.
The commenter identifies two
submissions made by CARB in March
2023 and June 2023 to provide
additional information relevant to the
original SIP submissions comprising the
Plan: the March 2023 Ammonia
Supplement and the March 2023
Building Heating Supplement,
discussing the ammonia precursor
demonstration and the BACM
requirement for building electrification,
and the Title VI Supplement, addressing
necessary assurances under CAA
section 110(a)(2)(E). CCEJN notes that
CAA section 110(a)(2) requires ‘‘[e]ach
implementation plan submitted by a
State under this chapter shall be
adopted by the State after reasonable
notice and public hearing.’’ The
commenter states that the supplements
are ‘‘required contents of such plans’’
and notes that the EPA’s supplemental
proposal for the 2012 annual PM2.5
NAAQS indicated the EPA’s expectation
that any Title VI necessary assurances
would go through state-level notice and
comment along with the remainder of
the Plan.
Because CARB submitted these
supplements directly to the EPA
without first going through additional
public process and after CARB had
formally submitted the Plan, the
commenter asserts that the EPA cannot
rely upon these supplements to approve
the State’s precursor demonstration,
BACM demonstration, or necessary
assurances under CAA section
110(a)(2)(E)(i).
Response 5: Generally, the EPA agrees
with CCEJN that SIP submissions must
meet the reasonable notice and public
hearing requirements of CAA section
110(a)(2). This is a basic requirement for
SIP submissions that appears in section
110(a)(1), section 110(a)(2), and section
110(l), as well as EPA regulations
pertaining to the completeness of SIP
submissions in 40 CFR part 51,
Appendix V. However, the EPA does
not agree that this requirement
necessarily applies to all information of
any type that a state may provide to the
EPA. This includes such instances as
when the state is providing additional
information to supplement a SIP
submission that did previously meet
notice and public hearing process
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requirements, particularly when the
EPA has requested that the state provide
such additional information to clarify an
ambiguity in the original SIP
submission or to aid the EPA in
evaluating adverse comments raising an
issue related to the original SIP
submission.157 The EPA considers it
appropriate to rely on such
supplemental information, even if it is
not in the form of a formal SIP
submission that underwent full notice
and public hearing process, when it
expands on and confirms information
presented in the state’s original SIP
submission or addresses potential
deficiencies in the pre-existing data.158
In such situations, the EPA considers
the relevant question to be whether the
state provided reasonable notice and
public hearing with respect to the issue
as part of the original SIP submission.
It would be illogical to require a state to
restart the entire SIP development
process and would delay the EPA’s
action on a SIP submission, thereby
potentially delaying needed emissions
reductions, were the Agency to interpret
CAA section 110(a)(2) notice and public
hearing requirements to apply to any
and all supplemental information
provided by state. Thus, the EPA
disagrees with CCEJN’s assertion that it
is inappropriate for the Agency to rely
on the additional information provided
by CARB in the two supplements in its
analysis of the SJV PM2.5 Plan because
it would violate the requirement under
section 110(a)(2) that plans submitted to
the EPA for inclusion in the SIP must
go through ‘‘reasonable notice and
public hearing.’’
With respect to the 2023 Ammonia
Supplement and the 2023 Building
Heating Supplement, the EPA believes
the information contained therein falls
within the EPA’s discretion to accept as
a supplement, as it expands upon and
confirms information provided in the
State’s previously submitted SIP
submissions that did undergo the full
notice and public hearing process.
CARB submitted the supplement to
‘‘support action on the attainment plan’’
and the supplement was intended as
‘‘clarifying information’’ rather than a
formal SIP revision.159 Also, CARB
157 The EPA has previously explained that it may
be appropriate to rely on a supplemental letter from
a state to resolve ambiguities in a SIP submission.
See 80 FR 33840, 33888 (June 12, 2015).
158 See 80 FR 33840, 33888 (‘‘It is the EPA’s
practice to neither require a state to resubmit a SIP
submission nor repropose action on the submission,
so long as the clarification provided in the
interpretive letter is a logical outgrowth of the
proposed SIP provision.’’).
159 Letter dated March 29, 2023, from Steven S.
Cliff, Executive Officer, CARB, to Martha Guzman,
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submitted this information in reaction
to prior comments related to the EPA’s
proposed action on the SIP submissions
with respect to the 2012 annual PM2.5
NAAQS, and in anticipation of
receiving those same comments in this
action. In this respect, CARB provided
additional information that it
anticipated the EPA would request to
help evaluate the issues raised in such
comments.
In the ammonia context, the 2018
PM2.5 Plan and 15 mg/m3 SIP Revision
present the fundamental elements of the
State’s demonstration that ammonia
does not contribute significantly to
exceedances of the 1997 annual PM2.5
NAAQS, including research that
supports its conclusion that ammonium
nitrate PM2.5 formation in the San
Joaquin Valley is NOX-limited rather
than ammonia-limited; 160 evidence that
the area’s measures targeting VOC
reductions are already reducing
ammonia; 161 and an analysis of how the
District’s control measures compare
with other state’s rules and
regulations.162 Upon initial review of
the State’s submission, and in light of
related comments received on
attainment plans for other PM2.5
NAAQS for the San Joaquin Valley, the
EPA requested clarifying information
and additional analysis to support the
State’s conclusions in the SJV PM2.5
Plan for the 1997 annual PM2.5
NAAQS.163 The information and
analysis the State provided in the March
2023 Ammonia Supplement does not
deviate from or fundamentally alter the
analysis in the SJV PM2.5 Plan; rather, it
provides a wide array of potential
controls and analyses to support the
fundamental conclusions in the
submitted SIP. The EPA believes that
CARB provided reasonable notice and
public hearing on its position with
respect to the ammonia precursor issue
in the initial SIP submission, and the
additional information in the March
2023 Ammonia Supplement merely
expands upon that position. Moreover,
by taking into account the information
that CARB provided in that supplement
Regional Administrator, EPA Region 9, with
enclosures.
160 2018 PM
2.5 Plan, Appendix G, pp. 9–10; CARB
December 2018 Staff Report, Appendix C, pp. 12–
15; Attachment A to CARB’s May 9, 2019, submittal
letter.
161 2018 PM
2.5 Plan, Appendix C, Section C–25.
162 Id.
163 40 CFR 51.1010 authorizes the EPA to require
supplemental information on potential controls
when the EPA deems it necessary to evaluate the
comprehensive precursor demonstration. The
regulations and EPA guidance do not instruct on
what state-level processes this supplemental
information should go through in being submitted
to the EPA. See PM2.5 Precursor Demonstration
Guidance, p. 31.
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during this rulemaking action, the EPA
itself has provided the commenters with
the opportunity to address that
supplemental information now.
Similarly, the building heating BACM
demonstration in the 2018 PM2.5 Plan
provides the foundations and analysis
for CARB’s conclusions that the State is
implementing BACM with respect to
building heating appliances. As
discussed in Section II.A.4, in 2020, the
EPA approved this demonstration as
meeting BACM for the 2006 24-hour
PM2.5 NAAQS.164 However, given
comments concerning this same issue
on an EPA proposal related to the 2018
PM2.5 Plan with respect to 2012 annual
PM2.5 NAAQS, the EPA requested that
the State support its conclusion with
more up-to-date, additional analysis.165
Like the supplemental information for
the ammonia precursor demonstration,
the March 2023 Building Heating
Supplement merely provides additional
support for the State’s original analysis
and determination that it is
implementing BACM for this source
category in the San Joaquin Valley area.
The EPA believes that CARB provided
reasonable notice and public hearing on
its position with respect to the building
heating and electrification issue during
the development of initial SIP
submission, and the additional
information in the March 2023 Building
Heating Supplement merely expands
upon that position.
Thus, the EPA believes the State
provided reasonable notice and
opportunity for public engagement with
respect to its conclusions in the
ammonia precursor demonstration and
building heating BACM elements of the
SIP and satisfied the reasonable notice
and public hearing requirements of the
CAA.166
With respect to the Title VI
Supplement, the EPA acknowledges that
164 85
FR 44192 (July 22, 2020).
FR 60494 (October 5, 2022); Comment letter
dated and received January 28, 2022, from Brent
Newell, Public Justice, et al., to Rory Mays, EPA
Region IX, including Exhibits 1 through 47. We
note, however, that there is no Exhibit 23; so, there
are 46 exhibits in total. Email dated February 1,
2022, from Brent Newell, Public Justice, to Rory
Mays, EPA Region IX. The 13 environmental, public
health, and community organizations are Public
Justice, Central Valley Environmental Justice
Network, Association of Irritated Residents, Central
Valley Air Quality Coalition, Leadership Counsel
for Justice and Accountability, Valley Improvement
Projects, The LEAP Institute, Little Manila Rising,
Center for Race, Poverty, and the Environment,
Central California Asthma Collaborative, Animal
Legal Defense Fund, National Parks Conservation
Association, and Food and Water Watch.
166 The EPA notes that a review of the State’s
records submitted with the SIP indicates that the
public did identify these two elements prior to and
during the public hearing held on the State’s
approval of the SIP in 2021.
165 87
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it provides additional information
related to an issue that the State did not
expressly address during the
development of the SJV PM2.5 Plan, i.e.,
the State did not previously engage in
public process specifically with respect
to CAA section 110(a)(2)(E) necessary
assurances that implementation of the
Plan would not be prohibited by Title
VI. However, in this instance, the issue
of necessary assurances arose in adverse
comments on a related EPA proposed
action on the same 2018 PM2.5 Plan with
respect to the 2012 PM2.5 NAAQS.167 In
order to address the concerns raised by
the commenter, the EPA sought
additional information from the State to
supplement the SJV PM2.5 Plan by
providing necessary assurances and
CARB provided that information in the
Title VI Supplement to do so.
In light of prior comments, and the
responsiveness of the Title VI
Supplement to the prior comments, the
EPA considers it appropriate to rely on
the additional information provided by
CARB in this way. Going forward, as
part of developing new SIP submissions,
the EPA requests that CARB and the
District include consideration of issues
related to compliance with Title VI as
part of that process, in order to ensure
public awareness and engagement. The
public notice and comment process
required for development of SIP
submissions provides an opportunity for
an air agency to share its position on
necessary assurances publicly, and to
develop the record supporting their
analysis of CAA section 110(a)(2)(E)(i)
as it pertains to a particular SIP
submission. Through this process, the
EPA expects states to develop adequate
necessary assurances so that they can be
reviewed during the air agency-level
public comment process and
subsequently by the EPA.168
167 86 FR 74310 (December 29, 2021). Some of the
environmental and community organizations that
contributed to the adverse comments related to
necessary assurances on the EPA’s proposed SIP
action for the 2012 annual PM2.5 NAAQS are among
the organizations that provided the adverse
comments on the EPA’s proposal for the 1997
annual PM2.5 NAAQS discussed herein.
168 The EPA notes that the content of the Title VI
Supplement is substantially similar to recent
submissions of necessary assurances from the State
on the attainment plan for the 2015 ozone NAAQS
(see ‘‘Staff Report, CARB Review of the San Joaquin
Valley 2022 Plan for the 70 ppb 8-Hour Ozone
Standard’’ (release date: December 16, 2022), pp.
21–23). The plan for the 2015 ozone NAAQS, which
was submitted after the EPA’s supplemental
proposal on the plan for the 2012 annual PM2.5
NAAQS, was made available for public review
during the State’s public comment processes (see
CARB’s ‘‘Notice of Public Meeting to Consider
Proposed San Joaquin Valley 70 parts per billion
Ozone State Implementation Plan,’’ dated December
16, 2022).
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B. Comments From Central Valley Air
Quality Coalition (CVAQ)
Comment 6: CVAQ’s comments cover
many of the same issues as the
comments from CCEJN. In summary,
they assert that the State’s plan
‘‘improperly relies upon faulty emission
inventories and modeling data, fails to
regulate key PM2.5 precursors like
ammonia and soil NOX, does not
analyze the most stringent measures
needed for attainment, and does nothing
to prove State compliance with Title VI
of the Civil Rights [Act] (Title VI).’’ The
commenter also notes that the two
CARB-submitted supplements did not
go through the State’s public process,
and that the EPA had an obligation to
issue a federal implementation plan in
January 2021 and has failed to do so.
Response 6: The EPA has addressed
CVAQ’s concerns about the emissions
inventory and modeling data in
Response 2.B; ammonia in Responses
3.A through 3.D; soil NOX in Responses
2.A and 4; MSM in Response 4; Title VI
in Responses 1.A and 1.B, Response 5,
and in Response 7 that follows; and the
State’s public process in Response 5 of
this document.
Regarding the EPA’s federal
implementation plan (FIP) obligation,
we do not dispute that the EPA has had
an obligation to implement a FIP for the
San Joaquin Valley for the 1997 annual
PM2.5 NAAQS due to a prior finding of
failure to submit the required
attainment plan. As we explained in the
proposed rule, as a result of the EPA’s
December 6, 2018 determination
effective January 7, 2019, that California
had failed to submit the required
attainment plan for the 1997 annual
PM2.5 NAAQS, among other required
SIP submissions for the San Joaquin
Valley, the EPA became subject to a
statutory deadline to promulgate a FIP
for this purpose no later than two years
after the effective date of that
determination—i.e., by January 7,
2021.169 However, as a result of this
final rulemaking approving all but the
contingency measure requirement of the
submitted Serious area and section
189(d) plan for the 1997 annual PM2.5
NAAQS, the only outstanding
deficiency for these NAAQS relates to
contingency measures. We note that
CARB has submitted three SIP
submissions to address the CAA
contingency measure requirements for
the 1997 annual PM2.5 NAAQS (as well
as other PM2.5 NAAQS) in the San
Joaquin Valley, including (1) the ‘‘PM2.5
Contingency Measure State
Implementation Plan Revision,’’
169 88
PO 00000
FR 45276, 45278.
Frm 00059
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86603
submitted to the EPA on June 8,
2023; 170 (2) amendments to District
Rule 8051 (‘‘Open Areas’’), submitted to
the EPA on October 16, 2023; 171 and (3)
the state-wide ‘‘California Smog Check
Contingency Measure for the State
Implementation Plan,’’ submitted to the
EPA on November 13, 2023.172 The EPA
will act on the contingency measure SIP
revisions, and/or promulgate a FIP for
the contingency measure requirement
for the 1997 annual PM2.5 NAAQS and
other NAAQS, in a separate rulemaking.
C. Comments From a Private Individual
Comment 7: The private citizen
commenter believes that the State’s plan
contains ‘‘aspirational and misleading
‘assurances’ of compliance with the
Civil Rights Act’’ and that the ‘‘EPA has
missed an opportunity to live up to the
commitments of the Biden
administration and EPA Administrator
Regan to prioritize environmental
justice and civil rights.’’
In addition, the commenter notes the
length of time that has passed since the
EPA committed to put out guidance on
what would constitute ‘‘necessary
assurances’’ under the Act and its
failure to do so prior to accepting the
necessary assurances demonstration in
the SJV PM2.5 Plan for the 1997 annual
PM2.5 NAAQS. The commenter
recommends that a simple interim
guidance could include: (1) ‘‘some sort
of equity or environmental justice
assessment,’’ and (2) ‘‘consideration of
alternative measures to lessen or
eliminate any potentially discriminatory
burdens revealed by that assessment.’’
The commenter provides a short
summary of the interaction between
CAA section 110(a)(2)(E) and Title VI at
the EPA, including identifying a SIP
rulemaking in 1997 where the
connection between section 110(a)(2)(E)
and Title VI was raised and a 2012
rulemaking pertaining to the San
Joaquin Valley on which the EPA
received comments about the same
issue.
The commenter generally
recommends that the EPA exercise its
discretion in determining what
constitutes necessary assurances to
require more from the State in favor of
a more rigorous posture as to what
constitutes necessary assurances. In
doing so, the commenter disputes the
170 Letter dated June 7, 2023, from Steven S. Cliff,
Executive Officer, CARB, to Martha Guzman,
Regional Administrator, EPA Region IX.
171 Letter dated October 13, 2023, from Steven S.
Cliff, Executive Officer, CARB, to Martha Guzman,
Regional Administrator, EPA Region IX.
172 Letter dated November 13, 2023, from Steven
S. Cliff, Executive Officer, CARB, to Martha
Guzman, Regional Administrator, EPA Region IX.
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EPA’s distinction in its proposal
between necessary assurances under
CAA section 110(a)(2)(E) and a formal
finding of compliance with Title VI.
Next, the commenter outlines the
contents of CARB’s Title VI supplement.
In particular, the commenter alleges that
CARB’s Civil Rights and Discrimination
Process does not have processes or
procedures for handling a complaint
originating from outside of CARB, that
the policy has been rarely used, and was
adopted prior to complaints filed at the
EPA against CARB for procedural
deficiencies in the State’s policy.
Additionally, the commenter believes
that neither the EPA nor CARB has
demonstrated that the State’s policy will
be implemented in a systemic manner to
avoid disproportionate effects.
The commenter asserts that the EPA’s
approval of the necessary assurances
conflates the concrete statutory
requirements of Title VI with policybased programs and policies of
environmental justice. The commenter
believes that relying on the policy-based
environmental justice initiatives does
not rise to the level of the systematic
and defined methods of Title VI
compliant laws.
The commenter then describes many
of the environmental justice resources
available to CARB and the EPA in
developing and determining the
adequacy of necessary assurances. The
commenter acknowledges that the EPA
identified many of these resources in its
proposal but believes the necessary
assurances discussion should
demonstrate that these resources were
considered and used in determining
whether there is a disproportionate
effect in a particular SIP-based action.
Ultimately, based on 2013 EPA
guidance on compliance with CAA
section 110(a)(2)(E) and the terms of
conditions under Title VI for CARB
receiving funding from the EPA, the
commenter does not believe that CARB
submitted a sufficient demonstration
that the required Title VI compliance
programs exist under CARB’s purview.
In their conclusion, the commenter
notes that the EPA could conditionally
approve the Plan, accompanied by an
enforceable condition requiring CARB
and the District to bring their programs
into demonstrated compliance with
Title VI.
Response 7: To the extent the
comment letter is providing input to the
EPA on content for a forthcoming
guidance document for CAA section
110(a)(2)(E)(i) with respect to Title VI,
such considerations are outside the
scope of this action.
As we noted in our proposal, the EPA
has discretion with regard to what may
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constitute necessary assurances under
CAA section 110(a)(2)(E)(i). For this
action, we believe the State has
provided adequate necessary assurances
to support approval, under these
specific facts and circumstances. The
EPA notes that what constitutes
necessary assurances for purposes of
Title VI for a given SIP submission
depends upon the facts and
circumstances of the Plan, and the
Agency may require more or different
information as needed in other SIP
actions. This finding does not limit the
Agency to review for different factors in
the future.
Importantly, as explained in the
proposal action, the EPA’s evaluation of
necessary assurances pertains to CAA
section 110(a)(2)(E)(i) compliance with
respect to a specific SIP submission, and
not to Title VI compliance more
broadly.173 Formal findings of
compliance with Title VI follow
procedures outlined in the CFR after
administrative complaints are filed with
the EPA alleging discrimination
prohibited by Title VI and the other
civil rights laws,174 or if the EPA
initiates an affirmative compliance
review.175 Section 110(a)(2)(E)(i), in
contrast, requires a state to provide
necessary assurances that the state’s
implementation of the SIP submission at
issue is not prohibited by federal law,
including Title VI. As an additional
point of clarification, this necessary
assurances analysis concerning Title VI
is distinct from considerations of
environmental justice more broadly.
Title VI involves specific considerations
of federal law as it pertains to
individuals on the basis of race, color,
or national origin. The language at issue
in CAA section 110(a)(2)(E)(i) is specific
to implementation of the SIP
submissions and prohibitions under
Title VI.
The EPA separately reviewed
information related to environmental
justice considerations and those
considerations are addressed in Section
IV of this document. The EPA reiterates
that in our proposed approval of the
Plan, the EPA completed a Demographic
Index analysis of the area subject to the
Plan, identifying environmental burdens
and susceptible populations in
disadvantaged communities in the San
Joaquin Valley nonattainment area. As
explained in more detail in Section
II.A.1 of this document, we believe the
State has provided the necessary
assurances, including information that
through its initial implementation that
173 88
FR 45276, 45320.
CFR 7.120.
175 40 CFR 7.115.
174 40
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the State has meaningfully considered
input from the public through public
outreach that is beyond the minimum
legal requirements for public comment
during SIP development, and that the
Plan submission complies with CAA
section 110(a)(2)(E)(i).
With respect to the ‘‘EPA’s processing
prior (to this 2023 action but subsequent
to the 2016 policy) complaints against
CARB and in which it had noted several
procedural deficiencies,’’ the EPA is not
aware of any complaints filed against
CARB within that time period regarding
CARB’s Civil Rights and Discrimination
Complaint Process, and no complaint
was specifically cited to by the
commenter.176 The EPA notes that it
publishes all external civil rights
complaints and compliance reviews
online.177
III. Motor Vehicle Emissions Budgets
and Transportation Conformity
The EPA previously determined that
the 2020 and 2023 motor vehicle
emissions budgets in the 15 mg/m3 SIP
Revision were adequate for use in
transportation conformity findings. 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
mg/m3 SIP Revision and found that they
are adequate for transportation
conformity purposes.178 The EPA
announced the availability of the
budgets and notified the public of the
adequacy finding via a Federal Register
176 On June 6, 2016, the EPA resolved a civil
rights complaint filed against CARB and the Bay
Area Air Quality Management District. After an
investigation by the EPA’s Office of Civil Rights
(OCR), the Agency found ‘‘insufficient evidence of
current non-compliance with Title VI or EPA’ s
Title VI regulation’’ and closed the complaint. In
the letter closing the complaint, the EPA notes that
‘‘OCR has provided technical assistance to CARB to
improve the elements of its non-discrimination
program,’’ including improvements to CARB’s Civil
Rights and Discrimination Complaint Process. The
closure letter specifically found ‘‘CARB has also
adopted a grievance procedure that is contained in
the Civil Rights Policy and Discrimination
Complaint Process that provides complainants a
prompt and impartial investigation of and response
to complaints filed with CARB alleging
discrimination in CARB’s programs or activities
prohibited by the federal non-discrimination
statutes.’’ The EPA does not believe this complaint
resolution and the conclusions therein conflicts
with the determinations in this final action. https://
www.epa.gov/sites/default/files/2016-06/
documents/2r-00-r9_carb_resolution_letter.pdf.
177 EPA, External Civil Rights Docket, https://
www.epa.gov/external-civil-rights/external-civilrights-docket-2014-present.
178 Letter dated February 1, 2022, from Matthew
Lakin, Acting Director, Air and Radiation Division,
EPA Region IX, to Richard Corey, Executive Officer,
CARB.
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notice on February 10, 2022.179 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.
The EPA proposed approval of these
same budgets, shown in Table 1 of this
document, on July 14, 2023.180 181 The
Plan establishes separate direct PM2.5
and NOX subarea budgets, based on
EMFAC2014, for each county, and
partial county (for Kern County), in the
San Joaquin Valley.182 The EPA
discussed the State’s evaluation of the
significance/insignificance factors for
ammonia, SO2, and VOC, and reentrained road dust emissions in the
proposed rule.183 In this action, the EPA
is finalizing approval of 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.
Therefore, consistent with the
transportation conformity regulation,184
motor vehicle emissions budgets are not
required for transportation-related
emissions of ammonia, SO2, and VOC
for purposes of the 1997 annual PM2.5
NAAQS in the San Joaquin Valley. In
addition, since neither the State nor the
EPA has made a finding that reentrained road dust emissions are
significant, under 40 CFR 93.103(b)(3)
and 93.122(f), re-entrained road dust
emissions are not required to be
included in the budgets for 1997 annual
PM2.5 NAAQS in the San Joaquin
Valley.
TABLE 1—MOTOR VEHICLE EMISSIONS BUDGETS FOR THE SAN JOAQUIN VALLEY FOR THE 1997 ANNUAL PM2.5 NAAQS
[Annual average, tons per day]
2020 (RFP year)
2023 (attainment year)
County
PM2.5
Fresno ......................................................................................
Kern .........................................................................................
Kings ........................................................................................
Madera .....................................................................................
Merced .....................................................................................
San Joaquin .............................................................................
Stanislaus ................................................................................
Tulare .......................................................................................
NOX
0.9
0.8
0.2
0.2
0.3
0.6
0.4
0.4
PM2.5
25.3
23.3
4.8
4.2
8.9
11.9
9.6
8.5
NOX
0.8
0.7
0.2
0.2
0.3
0.6
0.4
0.4
15.1
13.3
2.8
2.5
5.3
7.6
6.1
5.2
Source: 15 μg/m3 SIP Revision, Appendix D, Table 18. Budgets are rounded up to the nearest tenth of a ton.
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For the reasons discussed in Sections
IV.D and IV.E of the proposed rule, the
EPA is approving the attainment, RFP,
and 5 percent demonstrations,
respectively, in the SJV PM2.5 Plan. The
2020 RFP and 2023 attainment year
budgets 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 is
finalizing approval of the 2020 and 2023
budgets listed in Table 1 of this
document.
The Plan also included budgets for
direct PM2.5 and NOX emissions for
2017 (RFP milestone year) and 2026
(post-attainment quantitative milestone
year). We are not approving the 2017
budgets 185 or the post-attainment year
2026 budgets at this time. 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
179 87
FR 7834 (February 10, 2022).
FR 45276, 45322.
181 The EPA did not receive any comments
related to our proposed approval of the motor
vehicle emissions budgets during the 30-day
comment period.
182 40 CFR 93.124(c) and (d).
180 88
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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. However, 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.
Conformity Trading Mechanism
Also on July 14, 2023, the EPA
proposed to approve a trading
mechanism for transportation
conformity analyses that would allow
the MPOs in the area to use future
decreases in NOX emissions from onroad mobile sources to offset any onroad increases in direct PM2.5 emissions
as allowed for under 40 CFR
93.124(b).186 187 As described in the
proposed rule, the EPA reviewed the
trading mechanism and found it is
183 88
FR 45276, 45316–45317.
CFR 93.102(b)(2)(v).
185 We are not approving the 2017 budgets
because such budgets would not be used in any
future transportation conformity determination
because the Plan includes budgets for 2020.
186 88 FR 45276, 45322.
184 40
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appropriate for transportation
conformity purposes in the San Joaquin
Valley for the 1997 annual PM2.5
NAAQS.188 The methodology for
estimating the trading ratio for
conformity purposes is essentially an
update (based on newer modeling) to
the State’s approach, approved in the
previous plan, to model the effect of
areawide direct PM2.5 and NOX
emissions reductions on ambient PM2.5,
and to express the ratio of these
modeled sensitivities as an interpollutant trading ratio.
In a previous 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.189 Here, we similarly
find that the State’s approach is
reasonable and are approving the 6.5 to
1 NOX for PM2.5 trading mechanism as
enforceable components of the
187 The EPA did not receive any comments
related to our proposed approval of the trading
mechanism for transportation conformity during the
30-day comment period.
188 88 FR 45276, 45318–45319.
189 See 86 FR 49100, 49128 (September 1, 2021)
(proposed rule) and 86 FR 67343, 67346 (November
26, 2021) (final rule).
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transportation conformity program for
the San Joaquin Valley for the 1997
annual PM2.5 NAAQS. This trading ratio
replaces 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.190
IV. Environmental Justice
Considerations
As described in detail in our proposal,
the EPA reviewed environmental and
demographic data for the San Joaquin
Valley using the EPA’s environmental
justice (EJ) screening and mapping tool
(‘‘EJSCREEN’’),191 192 and compared the
data to the corresponding data for the
United States as a whole. The results of
the analysis are provided for
informational and transparency
purposes.
This final action approves the State’s
plan for attaining the 1997 annual PM2.5
NAAQS. Information on the 1997
annual PM2.5 NAAQS and its
relationship to 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 lowincome 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.
V. Final Action
For the reasons discussed in this final
rule, the proposed rule, and the related
technical support documents, under
CAA section 110(k)(3), the EPA is
approving the portions of the SJV PM2.5
Plan as meeting CAA requirements for
implementation of the 1997 annual
PM2.5 NAAQS as follows:
(1) We are finding that the 2013 base
year emissions inventories continue to
190 76
FR 69896.
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. These
indicators are included in EJSCREEN reports that
are available in the rulemaking docket for this
action.
192 EPA Region IX, ‘‘EJSCREEN Analysis for the
Eight Counties of the San Joaquin Valley
Nonattainment Area,’’ August 2022.
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satisfy the requirements of CAA section
172(c)(3) and 40 CFR 51.1008 for
purposes of both the Serious area and
the CAA section 189(d) attainment
plans, and to find that the forecasted
inventories for the years 2017, 2018,
2019, 2020, 2023, and 2026 provide an
adequate basis for the BACM, RFP, five
percent, and modeled attainment
demonstration analyses;
(2) We are approving the following
elements as meeting the Serious
nonattainment area planning
requirements:
(a) the BACM/BACT demonstration as
meeting the requirements of CAA
section 189(b)(1)(B) and 40 CFR
51.1010(a);
(b) the demonstration (including air
quality modeling) that the Plan provides
for attainment as expeditiously as
practicable as meeting the requirements
of CAA sections 179(d) and 189(b) and
40 CFR 51.1011(b);
(c) the RFP demonstration as meeting
the requirements of CAA sections
172(c)(2) and 171(1) and 40 CFR
51.1012; and
(d) the quantitative milestone
demonstration as meeting the
requirements of CAA section 189(c) and
40 CFR 51.1013;
(3) We are approving the following
elements as meeting the CAA section
189(d) planning requirements:
(a) the BACM/BACT demonstration as
meeting the requirements of CAA
sections 189(a)(1)(C) 193 and 189(b)(1)(B)
and 40 CFR 51.1010(c);
(b) the demonstration that the Plan
will, at a minimum, achieve an annual
five percent reduction in emissions of
NOX as meeting the requirements of
CAA section 189(d) and 40 CFR
51.1010(c);
(c) the demonstration (including air
quality modeling) that the Plan provides
for attainment as expeditiously as
practicable as meeting the requirements
of CAA sections 179(d) and 189(d) and
40 CFR 51.1011(b);
(d) the RFP demonstration as meeting
the requirements of CAA sections
172(c)(2) and 171(1) and 40 CFR
51.1012; and
(e) the quantitative milestone
demonstration as meeting the
requirements of CAA section 189(c) and
40 CFR 51.1013;
193 As discussed in Section III.B of the proposal,
a section 189(d) plan must address any outstanding
Moderate or Serious area requirements that have
not previously been approved. Because we have not
previously approved a subpart 4 RACM
demonstration for the San Joaquin Valley
nonattainment area, we also proposed to approve
the BACM/BACT demonstration in the SJV PM2.5
Plan as meeting the subpart 4 RACM/RACT
requirement for the area (88 FR 45276, 45322).
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(4) We are approving the motor
vehicle emissions budgets for 2020 and
2023 as shown in Table 1 of this final
rulemaking because they are derived
from approvable RFP and attainment
demonstrations and meet the
requirements of CAA section 176(c) and
40 CFR part 93, subpart A; and
(5) We are approving the trading
mechanism provided for use in
transportation conformity analyses for
the 1997 annual PM2.5 NAAQS, in
accordance with 40 CFR 93.124(b).
As discussed in Section I.B of the
proposal, on November 26, 2021, the
EPA partially approved and partially
disapproved portions of the 2018 PM2.5
Plan that addressed attainment of the
1997 annual PM2.5 NAAQS in the San
Joaquin Valley nonattainment area. The
elements that the EPA disapproved
include the attainment demonstration,
comprehensive precursor
demonstration, five percent annual
emissions reductions demonstration,
BACM demonstration, RFP
demonstration, quantitative milestones,
motor vehicle emissions budgets, and
contingency measures. This disapproval
was effective on December 27, 2021. In
a separate final partial approval and
partial disapproval action, also effective
December 27, 2021, the EPA
disapproved the contingency measure
element of the 2018 PM2.5 Plan as it
relates to the requirements for the
Serious area plan 2006 24-hour PM2.5
NAAQS and the Moderate area plan for
the 2012 annual PM2.5 NAAQS.194
In our November 26, 2021 final
disapprovals, we noted that offset and
highway sanctions under CAA sections
179(b)(2) and 179(b)(1), respectively,
would not apply if California submits,
and the EPA approves, a SIP submission
that corrects all of the deficiencies
identified in our final actions prior to
the imposition of sanctions.195 Through
this final approval action, we find that
California has corrected the deficiencies
associated with the Serious area and
CAA section 189(d) SIP elements for the
1997 annual PM2.5 NAAQS for the San
Joaquin Valley (except for the
contingency measures element). Thus,
upon the effective date of this final rule,
all sanctions and any sanctions clocks
associated with the Serious area and
CAA section 189(d) SIP elements for the
1997 annual PM2.5 NAAQS for the San
Joaquin Valley (except the contingency
measures element) will be permanently
terminated.
This final action does not address the
prior disapprovals of the contingency
measure elements for the 1997 annual
194 86
195 86
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FR 67329.
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PM2.5 NAAQS, the 2006 24-hour PM2.5
NAAQS, and the 2012 annual PM2.5
NAAQS. Therefore, all sanctions and
any sanctions clocks associated with the
disapprovals of the contingency
measure elements for those standards
will continue to apply in the San
Joaquin Valley as outlined in the
November 26, 2021 final disapprovals
unless or until the EPA approves a SIP
submission or submissions meeting the
outstanding contingency measure
requirements for these NAAQS. As
discussed in Response 6, CARB has
submitted three SIP submissions to
address the CAA contingency measure
requirements for the 1997 annual PM2.5
NAAQS, the 2006 24-hour PM2.5
NAAQS, and the 2012 annual PM2.5
NAAQS in the San Joaquin Valley. The
EPA will act on these submissions and
determine the effects on the sanctions,
if any, in accordance with 40 CFR 52.31
through one or more separate
rulemaking actions.
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VI. Statutory and Executive Order
Reviews
Under the Clean Air Act, the
Administrator is required to approve a
SIP submission that complies with the
provisions of the Act and applicable
federal regulations. 42 U.S.C. 7410(k);
40 CFR 52.02(a). Thus, in reviewing SIP
submissions, the EPA’s role is to review
state choices, and approve those choices
if they meet the minimum criteria of the
Act. Accordingly, this final action
merely approves State law as meeting
federal requirements and does not
impose additional requirements beyond
those imposed by State law. For that
reason, this action:
• Is not a significant regulatory action
subject to review by the Office of
Management and Budget under
Executive Orders 12866 (58 FR 51735,
October 4, 1993) and 14094 (88 FR
21879, April 11, 2023);
• Does not impose an information
collection burden under the provisions
of the Paperwork Reduction Act (44
U.S.C. 3501 et seq.);
• Is certified as not having a
significant economic impact on a
substantial number of small entities
under the Regulatory Flexibility Act (5
U.S.C. 601 et seq.);
• Does not contain any unfunded
mandate or significantly or uniquely
affect small governments, as described
in the Unfunded Mandates Reform Act
of 1995 (Pub. L. 104–4);
• Does not have federalism
implications as specified in Executive
Order 13132 (64 FR 43255, August 10,
1999);
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• Is not subject to Executive Order
13045 (62 FR 19885, April 23, 1997)
because it approves a State program;
• Is not a significant regulatory action
subject to Executive Order 13211 (66 FR
28355, May 22, 2001); and
• Is not subject to requirements of
Section 12(d) of the National
Technology Transfer and Advancement
Act of 1995 (15 U.S.C. 272 note) because
application of those requirements would
be inconsistent with the Clean Air Act.
In addition, the SIP is not approved
to apply on any Indian reservation land
or in any other area where the EPA or
an Indian tribe has demonstrated that a
tribe has jurisdiction. In those areas of
Indian country, the rule does not have
tribal implications and will not impose
substantial direct costs on tribal
governments or preempt tribal law as
specified by Executive Order 13175 (65
FR 67249, November 9, 2000).
Executive Order 12898 (Federal
Actions To Address Environmental
Justice in Minority Populations and
Low-Income Populations, 59 FR 7629,
Feb. 16, 1994) directs federal agencies to
identify and address
‘‘disproportionately high and adverse
human health or environmental effects’’
of their actions on minority populations
and low-income populations to the
greatest extent practicable and
permitted by law. The EPA defines
environmental justice (EJ) as ‘‘the fair
treatment and meaningful involvement
of all people regardless of race, color,
national origin, or income with respect
to the development, implementation,
and enforcement of environmental laws,
regulations, and policies.’’ The EPA
further defines the term fair treatment to
mean that ‘‘no group of people should
bear a disproportionate burden of
environmental harms and risks,
including those resulting from the
negative environmental consequences of
industrial, governmental, and
commercial operations or programs and
policies.’’
The State did not evaluate
environmental justice considerations as
part of its SIP submittal; the CAA and
applicable implementing regulations
neither prohibit nor require such an
evaluation. The EPA’s evaluation of
environmental justice is described in
the section of this document titled,
‘‘Environmental Justice
Considerations.’’ The analysis was done
for the purpose of providing additional
context and information about this
rulemaking to the public, not as a basis
of the action. Due to the nature of the
action being taken here, this action is
expected to have a neutral to positive
impact on the air quality of the affected
area. In addition, there is no information
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86607
in the record upon which this decision
is based that is inconsistent with the
stated goal of E.O. 12898 of achieving
environmental justice for people of
color, low-income populations, and
Indigenous peoples.
This action is subject to the
Congressional Review Act, and the EPA
will submit a rule report to each House
of the Congress and to the Comptroller
General of the United States. This action
is not a ‘‘major rule’’ as defined by 5
U.S.C. 804(2).
Under section 307(b)(1) of the Clean
Air Act, petitions for judicial review of
this action must be filed in the United
States Court of Appeals for the
appropriate circuit by February 12,
2024. Filing a petition for
reconsideration by the Administrator of
this final rule does not affect the finality
of this action for the purposes of judicial
review nor does it extend the time
within which a petition for judicial
review may be filed, and shall not
postpone the effectiveness of such rule
or action. This action may not be
challenged later in proceedings to
enforce its requirements. (See section
307(b)(2).)
List of Subjects in 40 CFR Part 52
Environmental protection, Air
pollution control, Incorporation by
reference, Particulate matter, Reporting
and recordkeeping requirements.
Authority: 42 U.S.C. 7401 et seq.
Dated: December 5, 2023.
Martha Guzman Aceves,
Regional Administrator, Region IX.
Part 52, chapter I, title 40 of the Code
of Federal Regulations is amended as
follows:
PART 52—APPROVAL AND
PROMULGATION OF
IMPLEMENTATION PLANS
1. The authority citation for Part 52
continues to read as follows:
■
Authority: 42 U.S.C. 7401 et seq.
Subpart F—California
2. Section 52.220 is amended by
adding paragraphs (c)(537)(ii)(A)(9) and
(10) and (c)(537)(ii)(B)(7), (8), and (9) to
read as follows:
■
§ 52.220
Identification of plan—in part.
*
*
*
*
*
(c) * * *
(537) * * *
(ii) * * *
(A) * * *
(9) CARB Resolution No. 21–21,
September 23, 2021, submitted as a
revision to the 2018 PM2.5 Plan on
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November 8, 2021, by the Governor’s
designee.
(10) ‘‘Staff Report, Proposed SIP
Revision for the 15 mg/m3 Annual PM2.5
Standard for the San Joaquin Valley,’’
August 13, 2021, submitted as a revision
to the 2018 PM2.5 Plan on November 8,
2021, by the Governor’s designee.
(B) * * *
(7) 2018 Plan for the 1997, 2006, and
2012 PM2.5 Standards (‘‘2018 PM2.5
Plan’’), adopted November 15, 2018
(portions pertaining to the 1997 annual
PM2.5 NAAQS only, and excluding
Chapter 4 (‘‘Attainment Strategy for
PM2.5üü), Chapter 5 (‘‘Demonstration of
Federal Requirements for 1997 PM2.5
Standards’’), Chapter 6 (‘‘Demonstration
of Federal Requirements for 2006 PM2.5
Standards’’), Chapter 7 (‘‘Demonstration
of Federal Requirements for 2012 PM2.5
Standards’’), Appendix D (‘‘Mobile
Source Control Measure Analyses’’),
Appendix H (‘‘RFP, Quantitative
Milestones, and Contingency’’), and
Appendix K (‘‘Modeling Attainment
Demonstration’’)).
(8) ‘‘Attainment Plan Revision for the
1997 Annual PM2.5 Standard,’’ August
19, 2021, excluding Appendix H,
section H.3 (‘‘Contingency Measures’’),
submitted as a revision to the 2018
PM2.5 Plan on November 8, 2021, by the
Governor’s designee.
(9) SJVUAPCD Governing Board
Resolution No. 21–08–13, August 19,
2021, submitted as a revision to the
2018 PM2.5 Plan on November 8, 2021,
by the Governor’s designee.
*
*
*
*
*
3. Section 52.237 is amended by
revising paragraph (a)(11) to read as
follows:
■
§ 52.237
Part D disapproval.
(a) * * *
(11) The contingency measures
portion of the 2018 Plan for the 1997,
2006, and 2012 PM2.5 Standards (‘‘2018
PM2.5 Plan’’), adopted November 15,
2018, are disapproved for San Joaquin
Valley with respect to the 1997 annual
PM2.5 NAAQS because they do not meet
the requirements of Part D of the Clean
Air Act.
*
*
*
*
*
4. Section 52.244 is amended by
adding paragraph (f)(4) to read as
follows:
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■
§ 52.244
Motor vehicle emissions budgets.
*
*
*
*
*
(f) * * *
(4) San Joaquin Valley, for the 1997
annual PM2.5 NAAQS only (years 2020
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and 2023 budgets only), approved
January 16, 2024.
[FR Doc. 2023–27088 Filed 12–13–23; 8:45 am]
BILLING CODE 6560–50–P
DEPARTMENT OF TRANSPORTATION
Maritime Administration
46 CFR Part 298
[Docket Number MARAD–2023–0086]
RIN 2133–AB98
Amendment to the Federal Ship
Financing Program Regulations;
Financial Requirements
Maritime Administration,
Department of Transportation.
ACTION: Final rule.
AGENCY:
This document serves to
inform interested parties and the public
that the Maritime Administration
(MARAD) is amending its regulations
implementing the Federal Ship
Financing Program’s (Title XI Program)
financial requirements. This action is
necessary to implement statutory
changes and update the existing
financial requirements imposed on Title
XI Program obligors to align with more
up-to-date vessel financing and federal
credit best practices.
DATES: This rule will be effective
January 16, 2024.
FOR FURTHER INFORMATION CONTACT:
David M. Gilmore, Director, Office of
Marine Financing, at (202) 366–5737, or
via email at marinefinancing@dot.gov.
You may send mail to Mr. Gilmore at
Department of Transportation, Maritime
Administration, Office of Marine
Financing, 1200 New Jersey Avenue SE,
Washington, DC 20590. If you have
questions on viewing the Docket, call
Docket Operations, telephone: (800)
647–5527.
SUPPLEMENTARY INFORMATION:
SUMMARY:
Background
The Secretary of Transportation,
through MARAD, is authorized to
provide guarantees of debt (obligation
guarantees) to finance all types of vessel
construction and shipyard
modernization and improvement,
except for fishing vessels. The Title XI
Program is a loan guarantee program,
administered by MARAD, which was
established under Title XI of the
Merchant Marine Act, 1936, Public Law
74–835, codified at 46 U.S.C. Chapter
537, as amended (the ‘‘Act’’). Title XI
provides for the full faith and credit of
the United States, acting by and through
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the Maritime Administrator, for the
payment of debt obligations for: (1) U.S.
shipowners for the purpose of financing
or refinancing U.S. flag vessels
constructed, reconstructed, or
reconditioned in U.S. shipyards; and (2)
U.S. shipyards for the purpose of
financing advanced shipbuilding
technology and modern shipbuilding
technology of a privately-owned
shipyard facility located in the U.S. As
the Title XI Program guarantees full
payment of the obligation’s unpaid
principal and interest in the event of a
default by the borrower, both the statute
and regulations contain several criteria
and requirements intended to reduce
the risk of a loan default. Though the
Title XI Program regulations have been
amended over the years, the current
financial requirements and limitations
remain substantially the same as when
MARAD introduced them in 1978. As
lending practices have evolved,
MARAD’s regulatory standards have not
changed to reflect modern lending
practices for vessel financing. For
example, when the regulations where
implemented, certain leases were not
included as an expense under generally
accepted accounting principles (GAAP),
but today GAAP requires that all leases
be included as an expense. Today,
retained earnings are also expected to be
included in any calculation of equity or
net worth pursuant to GAAP.
Accordingly, the modifications to the
regulations will eliminate confusion and
align the Title XI Program regulations
with modern accounting standards.
Prior to execution of a guarantee,
MARAD is bound by statute to, among
other things, make determinations of
economic soundness of the project and
the financial and operating capability of
the applicant. To that end, the Title XI
regulations currently require each
borrower, and operator if applicable, to
have and maintain: (1) working capital
of at least $1; (2) at least 90 percent of
its equity as shown on the last audited
balance sheet; and (3) long-term debt
not to exceed twice its equity. By this
amendment, MARAD is modernizing its
financial review process by removing
static financial covenants and loan
thresholds and replacing them with a
review and evaluation of the
creditworthiness of each borrower based
on revenue metrics based on federal
credit and maritime lending best
practices. The use of these revenue
metrics is intended to improve the
quality of MARAD financial
requirements applied to new borrowers.
As part of its regular programmatic
evaluation process, MARAD frequently
seeks feedback from potential applicants
E:\FR\FM\14DER1.SGM
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Agencies
[Federal Register Volume 88, Number 239 (Thursday, December 14, 2023)]
[Rules and Regulations]
[Pages 86581-86608]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-27088]
=======================================================================
-----------------------------------------------------------------------
ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 52
[EPA-R09-OAR-2023-0263; FRL-10941-02-R9]
Air Quality State Implementation Plans; Approvals and
Promulgations: California; 1997 Annual Fine Particulate Matter Serious
and Clean Air Act Section 189(d) Nonattainment Area Requirements; San
Joaquin Valley, CA
AGENCY: Environmental Protection Agency (EPA).
ACTION: Final rule.
-----------------------------------------------------------------------
SUMMARY: The Environmental Protection Agency (EPA or ``Agency'') is
taking final action to approve portions of state implementation plan
(SIP) revisions submitted by the State of California to meet Clean Air
Act (CAA or ``Act'') requirements for the 1997 annual fine particulate
matter (PM2.5) national ambient air quality standards (NAAQS
or ``standards'') in the San Joaquin Valley PM2.5
nonattainment area. Specifically, the EPA is approving those portions
of the submitted SIP revisions as they pertain to the Serious
nonattainment area and CAA section 189(d) requirements for the 1997
annual PM2.5 NAAQS, except for the requirement for
contingency measures which will be addressed in a separate rulemaking.
In addition, the EPA is approving the 2020 and 2023 motor vehicle
emissions budgets and the trading mechanism for use in transportation
conformity analyses for the 1997 annual PM2.5 NAAQS.
DATES: This rule is effective on January 16, 2024.
ADDRESSES: The EPA has established a docket for this action under
Docket ID No. EPA-R09-OAR-2023-0263. All documents in the docket are
listed on the https://www.regulations.gov website. Although listed in
the index, some information is not publicly available, e.g.,
Confidential Business Information (CBI) or other information whose
disclosure is restricted by statute. Certain other material, such as
copyrighted material, is not placed on the internet and will be
publicly available only in hard copy form. Publicly available docket
materials are available through https://www.regulations.gov, or please
contact the person identified in the FOR FURTHER INFORMATION CONTACT
section for additional availability information. If you need assistance
in a language other than English or if you are a person with a
disability who needs a reasonable accommodation at no cost to you,
please contact the person identified in the FOR FURTHER INFORMATION
CONTACT section.
FOR FURTHER INFORMATION CONTACT: Ashley Graham, Geographic Strategies
and Modeling Section (AIR-2-2), EPA Region IX, 75 Hawthorne Street, San
Francisco, CA 94105. By phone: (415) 972-3877 or by email at
[email protected].
SUPPLEMENTARY INFORMATION: Throughout this document, ``we,'' ``us,''
and ``our'' refer to the EPA.
Table of Contents
I. Summary of the Proposed Action
II. Public Comments and EPA Responses
A. Comments From Central California Environmental Justice
Network (CCEJN)
B. Comments From Central Valley Air Quality Coalition (CVAQ)
C. Comments From a Private Individual
III. Motor Vehicle Emissions Budgets and Transportation Conformity
IV. Environmental Justice Considerations
V. Final Action
VI. Statutory and Executive Order Reviews
I. Summary of the Proposed Action
On July 14, 2023, in accordance with CAA section 110(k)(3), the EPA
proposed to approve portions of SIP revisions submitted by the
California Air Resources Board (CARB) to meet CAA requirements for the
1997 annual PM2.5 NAAQS in the San Joaquin Valley
PM2.5 nonattainment area.\1\ The San Joaquin Valley is
classified as a Serious nonattainment area for the 1997 annual
PM2.5 NAAQS and is also subject to CAA section 189(d)
requirements because of the failure of the area to attain the 1997
annual PM2.5 NAAQS by the area's original Serious area
attainment date (i.e., December 31, 2015). The EPA's determination that
the area failed to attain by the original December 31, 2015 attainment
date triggered the requirement for the State to submit the SIP
revisions on which the EPA is taking final action in this document.\2\
---------------------------------------------------------------------------
\1\ 88 FR 45276.
\2\ 81 FR 84481 (November 23, 2016).
---------------------------------------------------------------------------
The SIP revisions on which we proposed action are those portions of
the ``2018 Plan for the 1997, 2006, and 2012 PM2.5
Standards'' (``2018 PM2.5 Plan'') \3\ and the ``San Joaquin
Valley Supplement to the 2016 State Strategy for the State
Implementation Plan'' (``Valley State SIP Strategy'') \4\ that pertain
to the 1997 annual PM2.5 NAAQS, and the ``Attainment Plan
Revision for the 1997 Annual PM2.5 Standard'' (``15
[micro]g/m\3\ SIP Revision'').\5\ CARB submitted the 2018
PM2.5 Plan and Valley State SIP Strategy to the EPA as a
revision to the California SIP on May 10, 2019, and submitted the 15
[micro]g/m\3\ SIP Revision on November 8, 2021. We refer to these three
submissions collectively as the ``SJV PM2.5 Plan'' or
``Plan.'' The SJV PM2.5 Plan was developed jointly by the
San Joaquin Valley Unified Air Pollution Control District (SJVUAPCD or
``District'') and CARB and addresses Serious area nonattainment plan
and CAA section 189(d) requirements for the 1997 annual
PM2.5 NAAQS in the San Joaquin Valley, except for the
requirement for contingency measures. The Plan includes the State's
demonstration that the area will attain the 1997 annual
PM2.5 NAAQS by December 31, 2023.
---------------------------------------------------------------------------
\3\ The 2018 PM2.5 Plan was adopted by the San
Joaquin Valley Unified Air Pollution Control District on November
15, 2018, and by CARB on January 24, 2019.
\4\ The Valley State SIP Strategy was adopted by CARB on October
25, 2018.
\5\ The ``15 [micro]g/m\3\ SIP Revision'' was adopted by the San
Joaquin Valley Unified Air Pollution Control District on August 19,
2021, and adopted by CARB on September 23, 2021.
---------------------------------------------------------------------------
Following submittal of the SJV PM2.5 Plan, CARB
transmitted to the EPA two technical supplements providing additional
information in support of the Plan. The first supplement, submitted on
March 30, 2023, included documents titled ``Ammonia: Supplemental
Information for EPA in Support of 15 [micro]g/m\3\ Annual
PM2.5 Standard, March
[[Page 86582]]
2023'' (``March 2023 Ammonia Supplement'') and ``Building
Electrification Technical Supplement for the 1997 Annual
PM2.5 NAAQS'' (``March 2023 Building Heating Supplement'').
The second supplement was submitted on June 15, 2023, and included
information on the State's consideration of Title VI of the Civil
Rights Act of 1964 (``Title VI'') in the context of SIP development to
provide necessary assurances for purposes of CAA section
110(a)(2)(E)(i) (``Title VI Supplement'').\6\
---------------------------------------------------------------------------
\6\ 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 EPA proposed to approve the best available control measures/
best available control technology (BACM/BACT) demonstration,\7\ the
five percent annual emissions reduction demonstration, the attainment
demonstration (including air quality modeling), the reasonable further
progress (RFP) demonstration, and the quantitative milestones
demonstration in the SJV PM2.5 Plan as meeting the Serious
nonattainment area and CAA section 189(d) planning requirements for the
1997 annual PM2.5 NAAQS. We also proposed to find that the
previously approved \8\ 2013 base year emissions inventories continue
to satisfy the requirements of CAA section 172(c)(3) and 40 CFR 51.1008
for purposes of both the Serious area and the CAA section 189(d)
attainment plans, and to find that the forecasted inventories for the
years 2017, 2018, 2019, 2020, 2023, and 2026 provide an adequate basis
for the BACM, RFP, five percent, and modeled attainment demonstration
analyses. Finally, we proposed to approve the motor vehicle emissions
budgets for 2020 and 2023 and the trading mechanism provided for use in
transportation conformity analyses.\9\
---------------------------------------------------------------------------
\7\ As discussed in Section III.B of the proposal, a section
189(d) plan must address any outstanding Moderate or Serious area
requirements that have not previously been approved. Because we have
not previously approved a subpart 4 RACM demonstration for the San
Joaquin Valley nonattainment area, we also proposed to approve the
BACM/BACT demonstration in the SJV PM2.5 Plan as meeting
the subpart 4 RACM/RACT requirement for the area. (88 FR 45276,
45322).
\8\ On November 26, 2021, the EPA finalized a partial approval
and partial disapproval of the 2018 PM2.5 Plan for the
1997 annual PM2.5 NAAQS, including approval of the 2013
base year emissions inventory in the Plan. 86 FR 67329.
\9\ An adequacy finding for the 2020 and 2023 motor vehicle
emissions budgets was effective on February 25, 2022. (87 FR 7834,
February 10, 2022).
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Please see our July 14, 2023 proposed rulemaking for additional
background and a detailed explanation of the rationale for our proposed
action.
II. Public Comments and EPA Responses
The public comment period for the proposed rulemaking opened on
July 14, 2023, the date of its publication in the Federal Register, and
closed on August 14, 2023. During this period, the EPA received three
comment submissions from the following entities: (1) a coalition of six
environmental and community organizations (collectively referred to
herein as ``CCEJN''),\10\ (2) a coalition of eight environmental and
community organizations (collectively referred to herein as
``CVAQ''),\11\ and (3) a private citizen commenter.\12\ We respond to
the comments herein.
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\10\ Comment letter dated and received August 11, 2023,
including 36 attachments, addressed to Ashley Graham, EPA Region IX.
The six environmental and community organizations, in order of
appearance in the letter, are the Central California Environmental
Justice Network, the Central Valley Air Quality Coalition,
Earthjustice, the Leadership Counsel for Justice and Accountability,
the National Parks Conservation Association, and Sierra Club--Kern-
Kaweah Chapter.
\11\ Comment letter dated and received August 14, 2023,
addressed to Martha Guzman, Regional Administrator, EPA Region IX.
The eight environmental and community organizations, in order of
appearance in the letter, are the Central Valley Air Quality
Coalition, Earthjustice, Sierra Club--Kern-Kaweah Chapter, the
National Parks Conservation Association, the Central California
Environmental Justice Network, Little Manila Rising, and Valley
Improvement Projects.
\12\ Comment letter dated and received August 14, 2023, from
Richard Grow, to Docket ID No. EPA-R09-OAR-2023-0263.
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A. Comments From Central California Environmental Justice Network
(CCEJN)
1. Necessary Assurances Required by CAA Section 110(a)(2)(E)
Comment 1.A: CCEJN questioned the EPA's proposed approval of the
SJV PM2.5 Plan because of concerns about the adequacy of the
necessary assurances that the State provided in the Title VI
supplement. The commenter contends that to comply with CAA section
110(a)(2)(E), a state's necessary assurances must relate to a state's
nonattainment plan SIP submission itself, not merely the public
processes carried out while preparing the plan or state laws and
policies outside of the plan. The commenter claims that the Title VI
Supplement fails to do this because it ``has nothing to do with'' the
specific contents of the SJV PM2.5 Plan. As an example, the
commenter points to the State's lack of a Title VI analysis supporting
its decision to not regulate ammonia as part of its PM2.5
reduction strategy and contends that this example indicates that the
State has failed to provide adequate necessary assurances.
Additionally, CCEJN asserts that the EPA's analysis of the Plan must
consider how the Plan itself complies with Title VI and that the EPA
did not do so in its proposal.
Response 1.A: The EPA agrees with the commenter that CAA section
110(a)(2)(E)(i) requires that a state provide necessary assurances that
implementing the SIP submission at issue would not be prohibited by
Title VI. However, the EPA disagrees with the commenter that the
necessary assurances provided by CARB, in conjunction with the
substantive elements of the Plan itself, are insufficient to show that
implementation of the Plan is not prohibited by Title VI, consistent
with CAA section 110(a)(2)(E)(i). The EPA explained its rationale
regarding its evaluation of the necessary assurances and CAA section
110(a)(2)(E)(i) in detail in our proposal.\13\
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\13\ 88 FR 45276, 45319-45321.
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As a point of clarification, the commenter includes references to
``compliance with Title VI'' as the relevant inquiry for purposes of
necessary assurances under CAA section 110(a)(2)(E)(i). The EPA does
not agree with this characterization of its responsibilities under the
CAA.\14\ In the proposal action, the EPA clearly noted that ``[t]he
EPA's proposed SIP approval does not constitute a formal finding of
compliance with Title VI or 40 CFR part 7.'' \15\ The EPA further noted
that ``[a]pproval of this SIP submission for purposes of CAA
110(a)(2)(E)(i) does not affect the EPA's discretion to enforce Title
VI and/or the EPA's civil rights regulations.'' \16\ Without making a
formal finding of compliance with Title VI, the EPA believes the
analysis in the EPA's proposed approval and in this
[[Page 86583]]
final rulemaking is consistent with CAA section 110(a)(2)(E)(i).\17\
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\14\ See El Comit[eacute] para el Bienestar de Earlimart et al.
v. EPA, 786 F.3d 688 (9th Cir. 2015) (``El Comit[eacute] effectively
contends the EPA should have evaluated California's assurances the
same way the EPA would have to deal with a pending Title VI
complaint setting forth allegations of a current violation. 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.'').
\15\ 88 FR 45276, 45321.
\16\ Id.
\17\ See El Comit[eacute] para el Bienestar de Earlimart et al.
v. EPA, 786 F.3d 688 (9th Cir. 2015) (``Section 110(a)(2)(E) . . .
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.'')
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With respect to the substance of the State's submission, the EPA
disagrees with the commenter that the public processes surrounding the
development and implementation of an attainment plan have no bearing on
necessary assurances under CAA section 110(a)(2)(E)(i). As stated in
the proposal, ``[w]hat 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.'' \18\ Further, the EPA
has discretion to determine what assurances are necessary and may
require more or different information as needed in other SIP
actions.\19\ For example, in other contexts, the EPA has identified
public participation as an established approach for recipients of EPA
assistance to provide meaningful access to programs and activities.\20\
Therefore, the EPA does not agree with the contention that methods of
providing for public participation are not relevant to the analysis of
necessary assurances under CAA section 110(a)(2)(E)(i).
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\18\ 88 FR 45276, 45320.
\19\ See id.
\20\ See, e.g., https://www.epa.gov/external-civil-rights/external-civil-rights-guidance. Although information on this website
is not specific to CAA section 110(a)(2)(E)(i) necessary assurances,
it provides information regarding public participation and
information provided to recipients of EPA assistance.
---------------------------------------------------------------------------
In the Title VI Supplement, the State described 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. It
also described steps the State and District took to solicit and respond
to public input following the local adoption of the Plan and to
implement the control measures and strategy outlined in the Plan. These
approaches are beyond minimum public notice and comment requirements
and provide relevant information and important context of the necessary
assurances under CAA section 110(a)(2)(E)(i) that the Plan was adopted
and will be implemented into the future in a manner that is not
prohibited by Title VI.
Similarly, the descriptions of State measures like Assembly Bill
617 (``AB 617'') and the development of community air monitoring
networks provide relevant context for the regulatory landscape in which
the State will implement the Plan, as well as the intent of the
regulators. The EPA believes the State initiatives to prevent or
diminish potential health-related impacts to communities most impacted
by air pollution also, in part, provide assurances that the
implementation of the Plan is not prohibited by Title VI in a manner
consistent with CAA section 110(a)(2)(E)(i). The State's Civil Rights
Policy, too, provides additional support for the conclusion that
implementation of the Plan would not be prohibited by Title VI. For
example, the policy would allow for members of the public to notify and
file a formal complaint with the State that an alleged violation of
Title VI is occurring ``during the administration of [the State's]
programs.'' \21\ Taken together, these various State processes and
initiatives support the conclusion that the State provided necessary
assurances that implementation of the plan would not be prohibited by
Title VI.
---------------------------------------------------------------------------
\21\ Title VI Supplement, p. 8.
---------------------------------------------------------------------------
The commenter points to one primary substantive deficiency in the
Plan that they believe indicates the State has not demonstrated
compliance with CAA section 110(a)(2)(E)(i): The commenter claims that
ammonia is a major precursor of PM2.5 and that the policy
decision ``to decline to regulate ammonia implicates disparate
treatment and/or disparate impact, yet CARB provides no necessary
assurances that this policy decision does not violate Title VI.'' The
EPA's proposed and final actions, based upon the State's SIP
submissions, reflect the EPA's agreement that ammonia is not a
significant precursor of PM2.5 for the purposes of the 1997
annual PM2.5 NAAQS in the San Joaquin Valley. As described
in more detail in Section II.A.3 of this document, this final
determination comes following the EPA's review of the State's submittal
and request for additional information to support the State's decision
not to regulate ammonia for this NAAQS, as well as the EPA's review of
the exhibits and attachments from the commenter. Included in the
State's submittal and March 2023 Ammonia Supplement are estimates of
the level of emissions reductions possible with a suite of potential
ammonia control measures, justifications for why many of these measures
are not feasible or are already being implemented in the area, and
ultimately, why the State has chosen to focus on reducing direct
PM2.5 and NOX to reduce PM2.5
concentrations in the San Joaquin Valley air basin. The EPA believes
the technical information provided by the State to support its decision
not to regulate ammonia for purposes of the 1997 annual
PM2.5 NAAQS provides adequate necessary assurances that the
implementation of this Plan will not be prohibited by Title VI.
The EPA recognizes that the San Joaquin Valley area has previously
struggled to attain the 1997 annual PM2.5 NAAQS and that the
Demographic Index analysis the EPA completed as a part of the proposed
approval indicates the area includes communities of color and low-
income populations above the national average. However, as explained in
this response and in our proposal, the EPA believes the information in
the record contains adequate necessary assurances consistent with CAA
section 110(a)(2)(E)(i). This analysis is based in part on technical
analyses such as that the modeling in the State's and District's Plan
shows attainment for these NAAQS by the applicable attainment date and
that the control strategy for PM2.5 takes into consideration
the unique atmospheric conditions in the San Joaquin Valley air basin
in which the PM2.5 response to reductions in ammonia
emissions would be relatively small. Thus, based on the existing
technical record before the EPA, we find that the State has adequately
provided necessary assurances that the implementation of the Plan is
consistent with CAA section 110(a)(2)(E)(i).
Comment 1.B: Next, CCEJN contends that the policies cited by CARB
in its Title VI supplement to support its necessary assurances, e.g.,
AB 617, community air monitoring networks, and CARB's Civil Rights
Policy, are not enforceable parts of the submitted Plan (pursuant to
CAA section 110(a)(2)(A)), cannot lead to credited emissions reductions
for SIP purposes, and thus cannot be relied upon as necessary
assurances.
Response 1.B: The EPA disagrees that necessary assurances must
themselves be enforceable parts of a plan. While in some instances a
state may submit additional enforceable measures as a component of
necessary assurances, the EPA believes that this is not a requirement.
The commenter cites the CAA section 110(a)(2)(A) requirement that plans
include enforceable emissions limitations and other control measures as
a basis for the assertion that necessary assurances must be enforceable
and part of the plan. The EPA agrees that nonattainment plans
[[Page 86584]]
must contain enforceable emissions limitations and other control
measures--but this does not mean that CAA section 110(a)(2)(E)(i)
necessary assurances must themselves be emissions limitations or
control measures. The EPA interprets section 110(a)(2)(E)(i) as
allowing an ``assurance'' to include an analysis of the plan. In this
context, a state providing adequate information to the EPA to provide
necessary assurances that the state is not prohibited by Title VI from
carrying out the plan in the SIP submission is sufficient. In the
proposal action, the EPA explained the rationale for this approach,
including citing to relevant case law finding that ``what assurances
are `necessary' is left to the EPA's discretion.'' \22\ This is
consistent with necessary assurances that the EPA requires when needed
for other issues related to section 110(a)(2)(E)(i). For example,
states also provide necessary assurances concerning the adequacy of
personnel, funding, and state law authority to implement a SIP
submission, and the EPA generally relies on facts, analyses, and other
forms of assurances from the state for these purposes--not enforceable
measures (that is, the EPA generally does not require SIP-approved
rules that are incorporated by reference into the Code of Federal
Regulations to provide such necessary assurances). There may be
circumstances under which the EPA would expect a state to provide a
state law provision for inclusion into the SIP in order to provide such
necessary assurances for these other requirements, but this is not
generally the case.
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\22\ 88 FR 45276, 45320. See also, El Comit[eacute] para el
Bienestar de Earlimart et al. v. EPA, 786 F.3d 688 (9th Cir. 2015).
---------------------------------------------------------------------------
Where a necessary assurances analysis concludes that additional
enforceable measures are needed, a state would also include such new
measures in the SIP submission, but necessary assurances need not
necessarily themselves constitute such measures, as the commenter
suggests. In this case, the EPA has concluded that the information
provided by the State concerning its existing policies and programs
provides adequate necessary assurances that the State's implementation
of the SIP submissions at issue would not be prohibited by Title VI.
2. Emissions Inventory
Comment 2.A: CCEJN states that the soil NOX emissions
estimate of approximately 10 tons per day (tpd) used in the modeling
emissions inventory was dubious when the State submitted the Plan in
2018 and that the estimate is clearly inaccurate based on more recent
studies, which the commenter claims suggest soil NOX may
contribute as much as 100 tpd to total NOX emissions. The
commenter also asserts that studies suggest that soil NOX
emissions are likely driven primarily by agriculture and therefore
should be considered anthropogenic. To support these assertions, the
commenter references Exhibit A to the letter (``Exhibit A''), which
summarizes 10 studies from 2015-2023, from which the author concludes
that 9 of the studies indicate that standard soil NOX
parameterizations underestimate agricultural soil NOX
emissions by a factor of 2 to 10.
CCEJN further states that ``[t]he state has acknowledged that its
existing inventory may be outdated, and it has begun the process of
studying NOX emissions from soil in order to update the
inventory for future submissions to EPA,'' but that its use of the
existing inventory in the interim ``. . . is unlawful because it is
based exclusively on inertia, and `the EPA cannot simply recite
``scientific uncertainty'' to evade its statutory duty to update
regulations' '' (citing A Cmty. Voice v. EPA, 997 F.3d 983, 994 (9th
Cir. 2021)). The commenter suggests that ``[i]nstead, the state must
make an updated good faith estimate--if not a perfect estimate--of
emissions, taking into account that the Clean Air Act is `preventative'
and `precautionary' in nature,'' and asserts that such estimate would
undoubtedly be higher than the estimate in the current inventory and
would identify significant anthropogenic soil NOX emissions.
Based on its analysis, CCEJN concludes that the EPA must disapprove
the inventory because it is neither ``current'' nor ``accurate'' and
that failure to do so is arbitrary and capricious.
Response 2.A: The EPA acknowledges the information provided by
CCEJN in its comments and in the studies described in Exhibit A
suggesting that soil NOX emissions may be higher than have
typically been estimated in the past. The studies cited by the
commenter rely on variants of several emissions estimation approaches,
including efforts to achieve better agreement between air quality
models and satellite measurements, and to correlate satellite
measurements over croplands with the expected soil temperature and
moisture dependence of soil NOX emissions. While most of the
studies cited by the commenter were published after the State developed
the emissions and conducted the modeling for the 2018 PM2.5
Plan upon which the 15 [micro]g/m\3\ SIP Revision is based, the EPA
would not characterize the studies as providing ``updated'' emissions
that would make the estimates in the 2018 PM2.5 Plan
obsolete, as suggested by the commenter. Rather, as discussed further
in the remainder of this response, we find that some recent studies
provide evidence that soils are an important NOX source, and
several provide alternative estimates of soil NOX emissions
using various approaches.
The EPA agrees that there is evidence suggesting soil
NOX emissions may be higher than previously estimated but
disagrees with the characterization in Exhibit A that 9 out of the 10
studies conclude that California soil NOX is underestimated
by a factor of 2 or more. That was the conclusion of two of the
studies, those described in Almaraz et al. (2018) \23\ and Sha et al.
(2021).\24\ Luo et al. (2022) \25\ did not opine on how their estimate
compares with prior estimates, though the authors did provide an
estimate that the author of Exhibit A notes implies that prior
estimates are largely underestimated. The other studies provide
evidence consistent with soil NOX as an important source or
suggest a stronger temperature dependence for soil NOX
emissions compared to previous approaches.
---------------------------------------------------------------------------
\23\ Almaraz et al. (2018), Agriculture is a major source of
NOX pollution in California, Science Advances, 4(1),
2018, doi:10.1126/sciadv.aao3477.
\24\ Sha et al. (2021), Impacts of soil NOX emission
on O3 air quality in rural California, Environmental
Science & Technology, 55(10), 7113-7122, doi:10.1021/
acs.est.0c06834.
\25\ Luo et al. (2022), Integrated Modeling of U.S. Agricultural
Soil Emissions of Reactive Nitrogen and Associated Impacts on Air
Pollution, Health, and Climate, Environmental Science & Technology,
56 (13), 9265-9276. doi:10.1021/acs.est.1c08660.
---------------------------------------------------------------------------
While there is evidence suggesting soil NOX emissions
may be higher than previously estimated, there are conflicting
conclusions in the literature. Because the inventories in the SJV
PM2.5 Plan reflect the State's best estimate based on the
information available at the time the Plan was developed, the EPA does
not believe a change in the soil NOX emissions estimation
approach relied on in the SJV PM2.5 Plan is warranted at
this time. There is a need to reconcile the disagreement among studies
by examining the differing assumptions, techniques, data sources,
locations, and time periods covered. Such further examination may also
help resolve the substantial uncertainty and variability of the
proportion of soil NOX emissions that can be attributed to
anthropogenic sources such as agricultural fertilizer application.
The EPA further disagrees with CCEJN's assertion that the State
relies
[[Page 86585]]
on the soil NOX emissions estimates in its existing
inventory due to ``inertia.'' As noted by the commenter, the State has
effectively acknowledged that its methodology for estimating soil
NOX emissions may need to be updated when it shared its
plans to convene a subject matter expert review panel to assess the
state of the science on soil NOX emissions and make
recommendations for future estimates.\26\ These efforts indicate that
the State is taking the issue seriously and attempting to address it,
as acknowledged by the commenter. However, in exploring possible
improvements to its soil NOX estimation approach, the State
is not disavowing the approach used in the SJV PM2.5 Plan,
nor is there a widely accepted soil NOX emissions inventory
approach that the State is willfully refusing to use. Depending on the
outcomes of the review panel's work, the State may find that its
current approach provides the best estimate and retain such approach,
or the State may determine that an alternative approach would provide a
more accurate estimate and use such approach moving forward.
---------------------------------------------------------------------------
\26\ SJVUAPCD, 2023 PM2.5 Plan for Attainment of the
Federal 2012 Annual PM2.5 Standard, Public Workshop,
slide 16, https://www.valleyair.org/Workshops/postings/2023/05-11-23_PM25/presentation.pdf. (A recording of the workshop is also cited
in the comment letter in fn. 39).
---------------------------------------------------------------------------
For the SJV PM2.5 Plan, the State used the
DeNitrification[hyphen]DeComposition model (DNDC) to estimate the 10
tpd of soil NOX emissions used in the modeling.\27\ The
approach is supported by research conducted in the same time frame as
studies cited by the commenter and therefore the EPA does not consider
the State's approach to be outdated. The emissions inventory in the
Plan was among the work that led to the paper by Guo et al. (2020),\28\
which was cited in Exhibit A as among the recent research on soil
NOX. Guo et al. (2020) did not find that soil NOX
emissions are significantly underestimated in the State's emissions
inventory. Rather, the study examined evidence from satellite
retrievals and ground-based measurements that indicate that the State's
approach provides an accurate emissions inventory for the San Joaquin
Valley. The EPA believes that the DNDC-based soil NOX
emissions used in the modeling are a good faith estimate consistent
with the State's current view of the state of the science, and that the
State's estimate is acceptable for use in the modeling emissions
inventory in the SJV PM2.5 Plan for the 1997 annual
PM2.5 NAAQS.
---------------------------------------------------------------------------
\27\ Email dated May 26, 2020, from Jeremy Avise, CARB, to Scott
Bohning, EPA Region IX, Subject: ``Soil NOX in ARB's
modeling'', with attached poster ``Preliminary Assessment of Soil
NOX Emissions from Agricultural Cropland in the San
Joaquin Valley''; ``Estimating Nitrogen Emissions from California's
Agricultural Lands'', March 5, 2019, presentation by Mike
Fitzgibbon, CARB, at 2019 California Climate & Agriculture Summit,
https://calclimateag.org/2019summit/.
\28\ Guo et al. (2020), Assessment of Nitrogen Oxide Emissions
and San Joaquin Valley PM2.5 Impacts From Soils in
California, Journal of Geophysical Research: Atmospheres, 125(24),
doi:10.1029/2020JD033304. Note that a web document with a DOI or
Digital Object Identifier, such as 10.1029/2020JD033304, may be
found via prefixing doi.org/ to the doi, as in: https://doi.org/10.1029/2020JD033304.
---------------------------------------------------------------------------
The EPA acknowledges that there is evidence that soil
NOX emissions have historically been underestimated,
including evidence from some studies finding that satellite
observations of column NO2 (total amount of NO2
in a vertical column of the atmosphere) indicate that soil
NOX emissions are higher than predictions by photochemical
models using emissions estimates from older soil NOX
parameterizations. The commenter describes some of such evidence in
Exhibit A. However, the case for soil NOX emissions being
significantly underestimated in the San Joaquin Valley is not as
settled as CCEJN's comment implies. The studies cited by the commenter
differ in the questions they attempt to address, their assumptions and
analytical approaches, their data analysis techniques and metrics, and
in the differing environmental conditions in the locations and time
periods they cover.
In the remainder of this response, we identify statements from the
ten research papers listed in Exhibit A to show that their support for
a substantially greater soil NOX emissions for the San
Joaquin Valley is not definitive, and that there is not an agreed upon
method to estimate a missing increment of emissions if one is in fact
needed. Note that these points are not meant to discredit the work of
the respective authors but rather to illustrate that there are varying
factors that require greater investigation to determine the magnitude
of soil NOX emissions in the San Joaquin Valley. Given these
complicating factors and uncertainties, the EPA requests that CARB and
the District continue their work to examine their current methodology
for estimating soil NOX emissions, and as appropriate,
revise their methodology based on the findings of the expert review
panel and the latest available research.
Oikawa et al. (2015) \29\ measured NOX emissions from
sorghum plots after applying fertilizer, and explored the effect of
higher soil NOX emissions on the performance of an air
quality model by comparing the model results with satellite
NO2 column observations and surface measurements. The study
authors concluded that soil NOX emissions would need to be
10 or more times higher to match observations. However, surface
measurements were not consistently underestimated in the model, and
increasing emissions in the model to match the satellite retrievals led
to overestimates in emissions at the surface derived from measurements
of soil NOX emissions fluxes. The paper also noted that
global estimates of soil NOX emissions from other studies
vary by a factor of three (ranging from 9 to 27 Tg per year),
indicating a high level of uncertainty. The study conclusions suggest
that soil NOX emissions are largely underestimated but the
magnitude of the underestimate is not quantified.
---------------------------------------------------------------------------
\29\ Oikawa et al. (2015), Unusually high soil nitrogen oxide
emissions influence air quality in a high-temperature agricultural
region. Nat. Commun., 6:8753, doi:10.1038/ncomms9753.
---------------------------------------------------------------------------
Parrish et al. (2017) \30\ focuses on understanding trends in ozone
design values, noting a difference in the San Joaquin Valley trend in
comparison with other California air basins. The authors note that the
difference may partially be accounted for by the higher agricultural
activity in the Valley, for which controls have not been implemented as
extensively as for other anthropogenic sources. While this explanation
could also hold for agricultural soil NOX, that particular
issue is not explored.
---------------------------------------------------------------------------
\30\ Parrish et al. (2017), Ozone Design Values in Southern
California's Air Basins: Temporal Evolution and U.S. Background
Contribution. J. Geophys. Res. Atmos., 122, 11166-11182,
doi:10.1002/2016JD026329.
---------------------------------------------------------------------------
Exhibit A cites Kleeman et al. (2019) \31\ as providing evidence of
a missing source of NOX emissions that could help correct a
``consistent underprediction'' in nitrate concentrations. The EPA
believes this underprediction was overstated. For the January average
of the three model years reported, there was a modest underprediction
of nitrate in the model base cases without soil NOX compared
to a somewhat larger overprediction when soil NOX emissions
were added; whereas for the 2010 model year, nitrate was overpredicted
in the base case and the overprediction was worsened in the
[[Page 86586]]
soil NOX case.\32\ In the conclusion, the authors state that
``further research is required to more accurately estimate winter
emissions rates of soil NOX and to account for year-to-year
variations driven by changes in meteorological conditions, fertilizer
application rates, and irrigation practices,'' and that the tests
conducted ``do not definitely prove that the missing emissions source
is indeed fertilized agricultural soils. Future measurements should be
made in the rural portions of the SJV to further test the hypothesis
that soil NOX emissions are a significant factor in the air
quality cycles within the region.'' \33\ The EPA interprets such
conclusions as an acknowledgement that additional research is needed,
with a focus on wintertime conditions when San Joaquin Valley
PM2.5 concentrations are highest.
---------------------------------------------------------------------------
\31\ Kleeman, M., A. Kumar, and A. Dhiman, ``Investigative
Modeling of PM2.5 Episodes in the San Joaquin Valley Air
Basin during Recent Years'' (CARB Contract No. 15-301, 2019),
available at https://ww2.arb.ca.gov/sites/default/files/classic/research/apr/past/15-301.pdf.
\32\ Id. at 60 and 63.
\33\ Id. at 77.
---------------------------------------------------------------------------
The author of Exhibit A summarizes a result from Chen et al.
(2020),\34\ noting acceptable PM2.5 model performance
despite overly low atmospheric mixing heights. But the author goes on
to suggest that overly low mixing heights should have led to
PM2.5 overpredictions; the good performance therefore may
imply that the PM2.5 precursor emissions were too low. The
study also found that rural site column NO2 was
underpredicted by 25 percent relative to NO2 columns derived
from surface-based measurements, suggesting that soil NOX
emissions are underestimated. Thus, the study authors acknowledge that
soil NOX emissions may need to be further examined. However,
they also note good agreement between modeled column NO2 and
the NO2 columns derived from surface-based measurements at
the urban sites of Fresno and Bakersfield, where NO2 is
double that of the rural sites, and state that ``it is unlikely that
NOX emissions from croplands are comparable to mobile
sources'' (the main source of NOX emissions). That is, the
NOX emissions increase that would be needed to increase the
model predictions by 25 percent for the low-NO2 rural sites
is unlikely to be comparable to the NOX emissions driving
the high NO2 urban sites. This finding supports further
exploration of soil NOX emissions, and a possible
underestimate, but does not imply a large underestimate in soil
NOX emissions.
---------------------------------------------------------------------------
\34\ Chen et al. (2020), Modeling air quality in the San Joaquin
valley of California during the 2013 Discover-AQ field campaign,
Atmospheric Environment: X, Volume 5, January 2020, 100067,
doi:10.1016/j.aeaoa.2020.100067.
---------------------------------------------------------------------------
Wang et al. (2021) \35\ explored the relatively modest downward
trend in satellite column NO2 measurements after 2009, as
compared to the steady decrease in anthropogenic NOX
emissions, and the role of soil NOX emissions in this
apparent discrepancy. They found better model agreement with satellite
column NO2 when they increased the temperature
responsiveness of their soil NOX emissions estimates,
especially at high temperatures. This change also improved the
correlation between modeled column NO2 and satellite column
NO2 in the central United States. This correlation is an
important finding, implying soil NOX emissions may be
underestimated. However, it should be noted that in absolute terms,
even without soil NOX, the model simulation overpredicted
the NO2 concentration relative to the satellite retrieval.
The authors acknowledge that there are many reasons why the predictions
might not match the observations. The authors cite an uncertainty of 35
percent in the satellite NO2 columns, and the uncertainty in
the satellite retrieval encompasses all of the results, from the zero
soil NOX scenario to the increased soil NOX
scenario.\36\ The EPA views this as a large enough uncertainty to limit
confidence in at least some of the study conclusions.
---------------------------------------------------------------------------
\35\ Wang et al (2021), Improved modelling of soil
NOX emissions in a high temperature agricultural region:
role of background emissions on NO2 trend over the US,
Environ. Res. Lett., 16, doi:10.1088/1748-9326/ac16a3.
\36\ Id. at Figure 3.
---------------------------------------------------------------------------
Wang et al. (2021) states that the downward trend in the satellite
column NO2 is smaller than the downward trend in
anthropogenic NOX emissions, and that the discrepancy is
greater for the central U.S. than for the eastern or western U.S. Since
the San Joaquin Valley is in the west, the EPA interprets this result
as indicating that there is less of a potential need for increases in
soil NOX emissions estimates in the San Joaquin Valley
relative to the central U.S. to resolve the discrepancy. The authors
also cited another study in which the apparent discrepancy between the
trends in modeled versus surface-level ambient measurements (as opposed
to the satellite retrieval) was found to be within the bounds of the
uncertainty of the ambient measurements. The study provides a strong
impetus for exploring soil NOX emissions and their potential
increased rate at higher temperatures but does not provide evidence
that soil NOX emissions are significantly underestimated in
the San Joaquin Valley.
To evaluate the human health and climate benefits of reducing
reactive nitrogen emissions, Luo et al. (2022) \37\ used the Fertilizer
Emission Scenario Tool for CMAQ (FEST-C) to generate soil
NOX emissions estimates for every U.S. county, including
those counties in the San Joaquin Valley. Exhibit A notes that the
FEST-C-derived San Joaquin Valley county total emissions of soil
NOX is 100 tpd compared to CARB's emissions inventory for
all anthropogenic NOX which amounts to roughly 200 tpd. The
study used a different emissions model than the model used by CARB,
underscoring the need to explore why emissions models yield such
different results. The study did not validate the model-derived
NO2 predictions using satellite retrievals or ground-based
measurements, so it does not provide direct evidence that soil
NOX emissions are underestimated for the San Joaquin Valley.
---------------------------------------------------------------------------
\37\ Luo et al. (2022), Integrated Modeling of U.S. Agricultural
Soil Emissions of Reactive Nitrogen and Associated Impacts on Air
Pollution, Health, and Climate, Environmental Science & Technology,
2022, 56 (13), 9265-9276. doi:10.1021/acs.est.1c08660.
---------------------------------------------------------------------------
Wang et al. (2023) \38\ explored trends in satellite column
NO2 and ground level measurements, and the role of lightning
and soil NOX in explaining spatial and temporal
distributions of NO2. Among other results, they found that
temperature and soil moisture, which are important drivers of soil
NOX emissions, were highly correlated with satellite column
NO2 in rural areas of California, including crop lands. This
suggests soil NOX is an important source of NOX
near crop lands. The study examined trends in NOX over time
rather than attempting to quantify soil NOX emissions and
therefore does not provide direct evidence that soil NOX
emissions are underestimated for the San Joaquin Valley.
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\38\ Wang et al (2023), Satellite NO2 trends reveal
pervasive impacts of wildfire and soil emissions across California
landscapes, Environ. Res. Lett., 18, doi:10.1088/1748-9326/acec5f.
---------------------------------------------------------------------------
Finally, three studies cited in Exhibit A, Almaraz et al. (2018),
Guo et al. (2020), and Sha et al. (2021), provided estimates of soil
NOX emissions in California. Almaraz et al. (2018) \39\
estimated soil NOX emissions using a top-down approach based
on aircraft measurements as well as the Integrated Model for the
Assessment of the Global Environment (IMAGE) soil model. Guo et al.
(2020) \40\ compared satellite measurements of NO2 with CMAQ
air quality model predictions using soil
[[Page 86587]]
NOX emissions from the DNDC soil model. Sha et al. (2021)
\41\ conducted a similar measurement-model comparison but using the
Weather Research and Forecasting model coupled with Chemistry (WRF-
Chem) air quality model and the Berkeley Dalhousie Iowa Soil NO
Parameterization (BDISNP) soil model. The IMAGE and BDISNP models are
empirical or parametric models. They rely on emissions factors that are
derived from empirical measurements and that may vary by land use,
precipitation, and temperature, but do not incorporate algorithms that
reflect the underlying physical principles. The DNDC model used in Guo
at al. (2020) and in the State's emissions inventory is a
biogeochemical or mechanistic model. It also uses measurements for
validation but includes detailed consideration of the individual
physical and biological processes in soils that lead to NOX
emissions and their dependence on factors like the soil's various
nitrogen- and carbon-containing species, moisture, and temperature.
---------------------------------------------------------------------------
\39\ Almaraz et al. (2018), Agriculture is a major source of
NOX pollution in California, Science Advances, 4(1),
2018, doi:10.1126/sciadv.aao3477.
\40\ Guo et al. (2020), op. cit.
\41\ Sha et al. (2021), Impacts of soil NOX emission
on O3 air quality in rural California, Environmental
Science & Technology, 55(10), 7113-7122, doi:10.1021/
acs.est.0c06834.
---------------------------------------------------------------------------
Comparisons between the results described in Almaraz et al. (2018),
Guo et al. (2020), and Sha et al. (2021) show large disagreements.\42\
Almaraz et al. (2018) estimated that soil NOX emissions from
fertilized croplands account for 32 percent of California
NOX emissions, Sha et al. (2021) estimated soil
NOX emissions comprise 40.1 percent of California's total
NOX emissions, while Guo et al. (2020) estimate that soil
NOX emissions are only 1.1 percent of California
anthropogenic NOX emissions. (As noted earlier in this
response, the DNDC model emissions estimation work performed for the
Guo et al. (2020) study was also the basis for the State's soil
NOX emissions estimate.) The fraction of nitrogen applied as
fertilizer released as NOX to the atmosphere was estimated
by Almaraz et al. (2018) to be 15 percent, while 7 other studies
reviewed by Guo et al. (2020) estimate it to be 2 percent or less.
Furthermore, there is an additional possible discrepancy between the
work described in Wang et al. (2021) \43\ and Wang et al. (2023),\44\
and the results in Guo et al. (2020). The former two found correlations
between satellite-derived column NO2 over agricultural areas
and modeled soil emissions, suggesting soil NOX as a driver
of NO2 there. However, using correlations and ratios of
NOX to CO among monitoring sites, and satellite column
NO2 retrievals, Guo et al. (2020) found little difference
between the diurnal and seasonal temporal variation at rural sites
compared to urban sites, consistent with a larger contribution of
emissions from urban sources rather than rural soils. Higher soil
NOX emissions would increase summer emissions more in rural
areas than in urban areas.
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\42\ The EPA also compared these studies in approving
California's 2020 emissions inventory submittal. 87 FR 59015, 59017-
59019 (February 9, 2022).
\43\ Wang et al. (2021), op. cit.
\44\ Wang et al. (2023), op. cit.
---------------------------------------------------------------------------
Despite widely differing estimates of the relative portion of
California's NOX emissions inventories attributable to soil
NOX in Almaraz et al. (2018), Sha et al. (2021), and Guo et
al. (2020), each study reported high agreement between its modeled and
its observed soil NOX emissions. Reconciling the differences
in input data used in the models, such as fertilizer and irrigation
amounts and timing; other inputs to the air quality models; and data
analysis techniques would be necessary for a process-based
understanding of the differences in the contribution and magnitude of
soil NOX emissions estimates between models. There is also a
need for additional measurements of soil NOX emissions
fluxes for various locations and conditions to help develop and
validate soil models.
The various authors acknowledge considerable uncertainty in their
work. While Almaraz et al. (2018) suggest that soil NOX
emissions may be significantly underestimated using current techniques,
the study acknowledges the limited number of surface measurements that
were available for purposes of validating the model results and that,
where observations exist, there is a large range in observed values due
to varying soil conditions (e.g., relating to temperature, moisture,
and fertilizer application). The ``top-down'' NOX emissions
estimates derived from aircraft measurements relied upon in the study
also reflect a significant degree of uncertainty, reported at 190 tpd
plus or minus 130 tpd, i.e., plus or minus 68 percent. The authors
acknowledge the limited number of surface measurements that were
available for purposes of comparing with the model results, the
difficulty in comparing the model results with the observations, and
the need for more field measurements. Guo et al. (2020) stated that
obtaining an emissions factor correlating NOX emissions to
fertilizer application from the presently available data in various
studies (including Almaraz et al. (2018)) would be ``difficult or
impossible'' due to the sparseness of data collected in terms of
sampling length, sampling frequency, and the episodic nature of
nitrogen gases from soil.
Most of the discussion herein concerns the varying estimates of
overall total soil NOX emissions. However, how those
emissions are distributed in time and space are also of great
importance for understanding the effect of NOX emissions on
ambient PM2.5 concentrations. PM2.5
concentrations in the San Joaquin Valley are highest in the cool, moist
winter, whereas soil NOX emissions are highest in the warm,
dry summer. For modeling PM2.5 concentrations, it is
especially important that the soil NOX approach that is used
performs well under wintertime conditions. Also important is how the
approach reflects soil composition, soil management practices, and
fertilizer application, each of which vary in time and space. Adopting
a different soil NOX emissions estimation approach is not a
matter of simply replacing one estimate of total soil NOX
with another. Rather, it requires ensuring that the approach accurately
reflects the spatial and temporal variation of the many factors
affecting emissions and of the emissions themselves.
In light of the uncertainties and disagreements among studies, the
EPA does not believe that the available research provides sufficient
certainty about the magnitude and proportion of soil NOX
emissions to warrant a revision to the State's inventory for purposes
of the SJV PM2.5 Plan.\45\ The EPA is not convinced that any
revised estimate developed by the State at this time would be
verifiably more accurate than the inventory in the Plan. A revision to
the State's inventory approach may be warranted in the future pending
the State's ongoing work in this area and the most up-to-date
understanding of soil NOX emissions, as discussed earlier in
this response. The EPA encourages the State to continue its ongoing
work to convene a subject matter expert review panel to assess the
state of the science on soil NOX emissions, to keep abreast
of the latest research, and to update its estimation methodologies, as
appropriate. However, for purposes of the SJV PM2.5 Plan for
the 1997 annual PM2.5 NAAQS that is the subject of this
action, we find that the State relied on a reasonable methodology that
is supported by the research literature. Thus, we conclude that the
State
[[Page 86588]]
provided an accurate, up-to-date emissions inventory for
NOX.
---------------------------------------------------------------------------
\45\ The EPA reached a similar conclusion in approving
California's 2020 emissions inventory submittal. 87 FR 59015, 59017-
59019 (February 9, 2022).
---------------------------------------------------------------------------
Comment 2.B: Regarding the motor vehicle emissions modeling, CCEJN
points to a previous statement from the EPA, saying that ``it could
approve an outdated inventory so long as the inventory was built using
the `latest EPA-approved' emission model `at the time [the State]
developed the submission.' '' The commenter asserts that the EPA now
``proposes to abandon both the statutory text and the already-lax
requirement to use the most recent EPA-approved model,'' by allowing
the State to rely on a model that is a decade old when two more recent
models are available, one of which (EMFAC2017) shows higher attainment-
year emissions of both NOX and PM2.5. CCEJN
contends that the State and the EPA speculate that the higher values
would not affect the attainment demonstration. However, CCEJN asserts
that the effect on the attainment demonstration is unknown and that it
is also unknown what the effects would be on the precursor
demonstration, which the commenter claims relies on low estimates of
NOX in 2023 to conclude that the State need not regulate
ammonia.
Finally, the commenter states that the ``EPA's decision to abandon
its recently adopted standard that inventories should be built using
the `latest EPA-approved' emission model is arbitrary and capricious,''
asserting that the EPA is ``simply resistant to the idea that a current
inventory must be used'' and has lost litigation over this issue
(citing Sierra Club v. EPA, 671 F.3d 955 (9th Cir. 2012)), and claiming
that ``. . .the agency is therefore bending over backwards to adopt
whatever standard will allow the state to continue to use the outdated
inventory.''
Response 2.B: The EPA disagrees with CCEJN's claims that we are
resistant to require, or have changed our position, that inventories
must be developed using the latest EPA-approved emissions model
available at the time the State developed the SIP submission and that
our proposed action to reaffirm the base year inventory is arbitrary
and capricious. As discussed in our proposal, the SJV PM2.5
Plan relies on much of the same technical information and analyses from
the 2018 PM2.5 Plan, including the emissions
inventories.\46\ The EPA previously found, for purposes of the 1997
annual PM2.5 NAAQS as well as other PM2.5
standards, that these inventories were based on the most current and
accurate information available to the State and District at the time
they were developing the 2018 PM2.5 Plan and inventories,
including the latest version of California's mobile source emissions
model that had been approved by the EPA at the time, EMFAC2014.\47\
Thus, as part of our prior action on the 2018 PM2.5 Plan for
the 1997 annual PM2.5 NAAQS, we approved the emissions
inventories as meeting the Serious area and CAA section 189(d)
requirements for the 1997 annual PM2.5 NAAQS.\48\
---------------------------------------------------------------------------
\46\ 88 FR 45276, 45279.
\47\ The EPA previously approved the emissions inventories in
the 2018 PM2.5 Plan as they pertain to the Serious area
and 189(d) requirements for the 1997 annual PM2.5 NAAQS
(86 FR 67329, November 26, 2021), the Serious area and 189(d)
requirements for the 1997 24-hour PM2.5 NAAQS (87 FR
4503, January 28, 2022), the Serious area requirements for the 2006
24-hour PM2.5 NAAQS (85 FR 44192, July 22, 2020), and the
Moderate area planning requirements for the 2012 annual
PM2.5 NAAQS (86 FR 67343, November 26, 2021).
\48\ 86 FR 67329.
---------------------------------------------------------------------------
In the EPA's final action approving the base year inventories in
the 2018 PM2.5 Plan for the 1997 annual PM2.5
NAAQS, the EPA addressed concerns raised by a commenter about the use
of EMFAC2014.\49\ The EPA discussed the timeline for the State's
submittal of the emissions inventories in the 2018 PM2.5
Plan relative to the EPA's approval of EMFAC2014 and EMFAC2017,
explaining that EMFAC2014 was the most current mobile source model
available for emissions inventory development purposes at the time the
State was developing the plan. Nevertheless, at that time, we
considered comparisons between EMFAC2014 and EMFAC2017 in the 2013 base
year as provided by CARB in its ``Staff Report, Proposed SIP Revision
for the 15 [micro]g/m\3\ Annual PM2.5 Standard for the San
Joaquin Valley'' (``CARB Staff Report'').\50\ Based on our review of
the State's analysis, we concluded that the 2013 base year emissions
inventories in the 2018 PM2.5 Plan were comprehensive,
accurate, and current, consistent with the requirements of CAA section
172(c)(3) and 40 CFR 51.1008.
---------------------------------------------------------------------------
\49\ Id. at 67332-67334.
\50\ CARB, ``Staff Report, Proposed SIP Revision for the 15
[micro]g/m\3\ Annual PM2.5 Standard for the San Joaquin
Valley,'' release date August 13, 2021.
---------------------------------------------------------------------------
Given that the 15 [micro]g/m\3\ SIP Revision was submitted to the
EPA by the State as an ``administrative revision'' to the 2018
PM2.5 Plan and relies on much of the same technical
information that was developed for the 2018 PM2.5 Plan, the
State continued to rely on the previously approved emissions
inventories from the 2018 PM2.5 Plan. However, to address
the most up-to-date information available, in addition to the EMFAC2017
model results noted earlier in this response, the State provided to the
EPA comparisons between the estimated annual NOX and
PM2.5 emissions developed for the 2018 PM2.5 Plan
using EMFAC2014 with those developed using the most recent EPA-approved
version of EMFAC, EMFAC2021.\51\ CARB's analysis included comparisons
between all three EMFAC models for both the 2020 RFP year and the 2023
attainment year.\52\ As the commenter correctly notes, model results
from EMFAC2017 indicate higher NOX and PM2.5
emissions in the 2023 attainment year than those derived for the same
year using EMFAC2014. However, EMFAC2021, which was the most recent
EPA-approved model at the time of the EPA's proposal,\53\ indicates
that NOX and PM2.5 emissions in the 2023
attainment year are lower than those derived for the same year using
EMFAC2014.
---------------------------------------------------------------------------
\51\ 88 FR 45276, 45284-45285.
\52\ Id.
\53\ The EPA approved the use of EMFAC2021 for use in SIP
development on November 15, 2022 (87 FR 68483).
---------------------------------------------------------------------------
As discussed in the EPA's technical support document (TSD) for our
proposal,\54\ the differences in emissions estimates for mobile sources
between the three EMFAC model versions correspond to differences of
approximately two percent or less of the regional emissions inventories
for PM2.5 and NOX for the 2023 attainment
year.\55\ Using the sensitivity of the PM2.5 design value
per tpd of emissions modeled by the State, the EPA assessed the effects
of the various EMFAC model version results on the attainment
demonstration in the Plan.\56\ Based on our technical analysis, we
determined that although the NOX and PM2.5
emissions estimates in the 2023 attainment year are higher in EMFAC2017
than in EMFAC2014, the effect on the PM2.5 concentrations of
0.07 [micro]g/m\3\ is sufficiently small that the attainment
demonstration remains valid.\57\ Furthermore, more up-to-date emissions
data from EMFAC2021 show lower emissions of NOX and
PM2.5 in the attainment year, indicating that the attainment
modeling results in the Plan derived using EMFAC2014 are conservative.
The same is true for the modeling for the precursor demonstration--the
lower NOX estimates derived using EMFAC2021 would produce
lower sensitivities of PM2.5 to ammonia, since they would
increase the abundance of ammonia
[[Page 86589]]
relative to NOX (since particulate ammonium nitrate
formation would be less limited by, and so less sensitive to, the
amount of ammonia). Therefore, the State's conclusions based
on their use of EMFAC2014 are conservative relative to if it had used
the most up-to-date EPA-approved model, EMFAC2021. Thus, we disagree
with the assertions that the effects of the various EMFAC versions on
the attainment demonstration and precursor demonstration are unknown
and find that reliance on the previously approved emissions inventories
is acceptable.
---------------------------------------------------------------------------
\54\ EPA, ``Technical Support Document, San Joaquin Valley
PM2.5 Plan Revision for the 1997 Annual PM2.5
NAAQS,'' April 2023.
\55\ Id. at 53.
\56\ Spreadsheet ``EMFAC update effect on annual 1997 p.m.2.5
NAAQS attainment demonstration.xlsx,'' EPA Region IX, May 1, 2023.
\57\ Id.
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Finally, we also disagree with the commenter's assertion (citing
Sierra Club) \58\ that the EPA has lost litigation over the issue that
a current inventory must be used. In Sierra Club, the Ninth Circuit
remanded the EPA's March 2010 approval of an ozone attainment plan for
the San Joaquin Valley submitted in 2004, holding that the EPA's
failure to consider new emissions data that the State had submitted in
2007 as part of a separate ozone plan rendered the EPA's action
arbitrary and capricious under the Administrative Procedure Act.\59\
The decision in that case rested on the unreasonableness of the EPA's
failure to address the new emissions data. The court found the EPA's
action arbitrary and capricious because of its ``reliance on old data
without meaningful comment on the significance of more current compiled
data'' and concluded that ``it was unreasonable for EPA summarily to
rely on the point of view taken [in longstanding policy] without
advancing an explanation for its action based on `the facts found and
the choice made.' '' \60\
---------------------------------------------------------------------------
\58\ Sierra Club v. EPA, 671 F.3d 955 (9th Cir. 2012).
\59\ Id. The court also noted that the EPA's action was
inconsistent with the court's holding in Ass'n of Irritated
Residents (AIR) v. EPA, 632 F.3d 584 (9th Cir. 2011) (amended and
superseded by Ass'n of Irritated Residents v. U.S. EPA, 686 F.3d
668, 671 (9th Cir. 2012)), which ``supports the proposition that if
new information indicates to EPA that an existing SIP or SIP
awaiting approval is inaccurate or not current, then, viewing air
quality and scope of emissions with public interest in mind, EPA
should properly evaluate the new information and may not simply
ignore it without reasoned explanation of its choice.'' Id. at 967.
\60\ Id. at 968 (citing Burlington Truck Lines v. United States,
371 U.S. 156, 168 (1962)).
---------------------------------------------------------------------------
For purposes of this action, the EPA has reviewed the emissions
data derived using more recent versions of the EMFAC model provided by
CARB, consistent with the holding in Sierra Club. Based on our
technical analysis of the latest information available described
earlier in this response, we determined that the precursor and
attainment demonstrations are valid. Thus, we continue to find that the
2013 base year inventories in the SJV PM2.5 Plan for the
1997 annual PM2.5 NAAQS satisfy the requirements of CAA
section 172(c)(3) and 40 CFR 51.1008 for purposes of both the Serious
area and the CAA section 189(d) attainment plan requirements, and to
find that the forecasted inventories provide an adequate basis for the
BACM, RFP, and the modeled attainment demonstration analyses in the
Plan.
3. Ammonia Precursor Demonstration
Comment 3: CCEJN states that the EPA must disapprove the ammonia
precursor demonstration based on considerations outlined in several
specific comments (summarized in Comments 3.A through 3.D that follow),
but also in several introductory remarks. In the introductory remarks,
the commenter appears to refer to the precursor demonstration's modeled
PM2.5 responses to ammonia reductions for the 2020 analysis
year, some of which are above the 0.2 [micro]g/m\3\ EPA-recommended
contribution threshold for the 2012 annual PM2.5 NAAQS in
the EPA's ``PM2.5 Precursor Demonstration Guidance''
(``PM2.5 Precursor Demonstration Guidance'').\61\ Based on
these model results, the commenter asserts that the State tacitly
acknowledges that ammonia assessments in previous PM2.5
plans, finding that ammonia does not contribute significantly to
PM2.5 levels that exceed the 1997 annual PM2.5
NAAQS, were incorrect. The commenter concludes that these results
indicate that the State should have been regulating ammonia in the
recent past, and also that the State should err on the side of caution
and regulate ammonia now. Finally, CCEJN contends that not regulating
ammonia has led to greater ammonium nitrate PM2.5, thereby
implicating disparate treatment and disparate impacts, and that the
State has failed to provide necessary assurances that the policy
decision not to regulate ammonia complies with Title VI.
---------------------------------------------------------------------------
\61\ ``PM2.5 Precursor Demonstration Guidance,'' EPA-
454/R-19-004, May 2019, including memorandum dated May 30, 2019,
from Scott Mathias, Acting Director, Air Quality Policy Division and
Richard Wayland, Director, Air Quality Assessment Division, Office
of Air Quality Planning and Standards (OAQPS), EPA, to Regional Air
Division Directors, Regions 1-10, EPA.
---------------------------------------------------------------------------
Response 3: The EPA disagrees with the commenter's premise that the
modeled PM2.5 responses for the 2020 analysis year indicate
that ammonia contributed significantly to PM2.5 levels in
the past. Under the EPA's PM2.5 Precursor Demonstration
Guidance, a response above the recommended contribution threshold
indicates a ``contribution,'' but additional information can be
considered in determining whether that response ``contributes
significantly.'' \62\ Such information may include, but is not limited
to, the amount by which the threshold is exceeded, studies to evaluate
specific atmospheric chemistry in the area, trends in ambient
speciation data and precursor emissions,\63\ and the general facts and
circumstances of the nonattainment area.\64\ In concluding that ammonia
does not contribute significantly, the State considered model responses
for the 2024 analysis year in addition to 2020, as well as other
additional information, as summarized in the EPA's February 2020
Precursor Technical Support Document.\65\ We do not believe that
viewing modeled responses to ammonia for specific years in isolation or
out of context is an adequate method for determining whether a
precursor contributes significantly to PM2.5 levels.
---------------------------------------------------------------------------
\62\ PM2.5 Precursor Demonstration Guidance, pp. 17-
19.
\63\ Id.
\64\ Id. at 14; 40 CFR 51.1006(a)(1)(ii).
\65\ ``Technical Support Document, EPA Evaluation of
PM2.5 Precursor Demonstration, San Joaquin Valley
PM2.5 Plan for the 2006 PM2.5 NAAQS,''
February 2020.
---------------------------------------------------------------------------
Additionally, the EPA does not agree that prior precursor
assessments should be considered erroneous based on the analysis in a
newer plan, particularly when the more recent plan uses different
criteria for assessing precursor significance. Previous plans for the
1997 annual PM2.5 NAAQS in the San Joaquin Valley, like the
ones mentioned by the commenter, predated the 2016 ``Fine Particulate
Matter National Ambient Air Quality Standards: State Implementation
Plan Requirements'' (``PM2.5 SIP Requirements Rule'') \66\
and the 2019 PM2.5 Precursor Demonstration Guidance;
therefore, they did not assess a modeled ammonia response relative to a
contribution threshold but rather relied on the conclusions from
modeling performed at the time and from past studies indicating that
ammonium nitrate PM2.5 is far more responsive to
NOX reductions than to ammonia reductions. Following
promulgation of the PM2.5 SIP Requirements Rule, the EPA now
requires that each precursor be evaluated individually by comparing
modeled responses to the contribution threshold and considering
additional information.\67\ The State conducted its precursor analysis
for the SJV PM2.5
[[Page 86590]]
Plan in accordance with these requirements.
---------------------------------------------------------------------------
\66\ 81 FR 58010 (August 24, 2016).
\67\ 40 CFR 51.1006; EPA's PM2.5 Precursor
Demonstration Guidance.
---------------------------------------------------------------------------
Regarding CCEJN's Title VI-related concerns, we address the
comments regarding Title VI in Responses 1.A, 1.B, 5, and 7, which rely
on supporting information discussed in Responses 3.A, 3.B.1 through
3.B.4, 3.C, and 3.D.
Comment 3.A: CCEJN's first specific stated concern with the
precursor demonstration is that the State's conclusion that the San
Joaquin Valley is NOX-limited relies on low NOX
estimates based on soil NOX emissions that are biased low.
The commenter asserts that ``. . .the state's estimates of soil
NOX emissions are on the extreme low-end of those reported
in the academic literature, and the state has acknowledged that it is
unsure how much NOX is actually emitted from soil in the
Valley.'' The commenter asserts that the State's only rationale for
maintaining the current estimate is that it will take time to develop a
new estimate, even though including anthropogenic soil NOX
emissions has been a longstanding request by Valley advocates.
Additionally, CCEJN asserts that ``[t]he state's reliance on very
low estimates of soil NOX emissions is contrary to the
presumption that precursors should be regulated and to the overall
`preventative' and `precautionary' tenor of the Act.'' The commenter
asserts that even if there was not sufficient time to fully evaluate
the scientific literature, a key question is what assumptions the State
should rely on in the interim. The commenter proposes that the State
should base its decision of whether to regulate ammonia on a median
reasonable estimate of soil NOX emissions, if not the high-
end estimate.
Response 3.A: We do not agree that the information provided by the
commenter on soil NOX emissions undermines the State's
conclusion that PM2.5 formation in the San Joaquin Valley is
NOX-limited (i.e., much more sensitive to NOX
emissions reductions than to ammonia emissions reductions). Three lines
of evidence support the EPA's agreement with the State's conclusion.
First, at this time, it is not clear that soil NOX emissions
estimates are largely underestimated as the commenter suggests. Second,
ammonia emissions are likely underestimated and so the response to an
ammonia reduction is likely overestimated in the modeling. Third,
ambient measurements strongly suggest that PM2.5
concentrations would respond relatively little to ammonia emissions
reductions. We discuss each of these lines of evidence in the
paragraphs that follow.
We do not dispute that increasing NOX emissions in the
model would be expected to decrease the modeled amount of ammonia
relative to NOX and increase the modeled sensitivity of
PM2.5 concentrations to ammonia reductions. However, as
discussed in detail in Response 2.A, further investigation is needed
and merited regarding whether soil NOX emissions are
underestimated or the magnitude of such underestimation. The magnitude
of the difference, if any, could have an important effect on whether
the model responses to ammonia reductions would be above the
contribution threshold. Additionally, even if it is determined that
soil NOX emissions are underestimated, proper updating of
the model emissions inventory to address the relative abundance of
ammonia and NOX could require updates to both the
NOX and ammonia emissions inventories, and there is ample
evidence that ammonia emissions are underestimated. Furthermore,
independent of any emissions estimates or modeling, evidence from
ambient measurements imply that PM2.5 concentrations would
respond very little to ammonia reductions, and that the model responses
in the precursor demonstration may be overestimated, as discussed
further in the remainder of this response. Thus, the EPA disagrees with
the commenter's assertions that the State's conclusion that the San
Joaquin Valley is NOX-limited (in the sense that it is much
more sensitive to NOX reductions than to ammonia reductions)
is based on biased soil NOX emissions estimates that compel
the EPA to disapprove the ammonia precursor demonstration.
A second line of evidence is that multiple studies have suggested
that ammonia emissions are underestimated in the San Joaquin Valley.
These studies reached this conclusion by comparing ambient measurements
and satellite retrievals to model results that incorporate estimates of
ammonia emissions, and by comparing monitoring or modeling results to
what would be expected based on the size(s) of the ammonia and
NOX emissions inventories. For example, in a summary report
for the CalNex air quality study, the authors concluded based on direct
measurements of ammonia emissions flux that ``[p]reliminary results
indicate that within the San Joaquin Valley, [ammonia] emissions could
be underestimated in inventories by about a factor of three.'' \68\
This finding was confirmed in later modeling using monitored data from
the DISCOVER-AQ field study.\69\ Other studies identified in a
literature search also suggest that ammonia emissions are
underestimated, as discussed in the remainder of this response. If
higher ammonia emissions were used in the modeling to correct the
underestimation, then modeled ammonia would be more abundant relative
to nitrate, and particulate nitrate formation would be more
NOX-limited. Thus, the modeled response to ammonia
reductions would be lower than reported in the precursor demonstration
in the SJV PM2.5 Plan, and below the contribution threshold.
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\68\ Parrish, D. (2014), Synthesis of Policy Relevant Findings
from the CalNex 2010 Field Study, Final Report to the Research
Division of the California Air Resources Board, 2014, p. 63;
available at https://csl.noaa.gov/projects/calnex/synthesisreport.pdf.
\69\ Kelly, J.T. et al. (2018), Modeling
NH4NO3 over the San Joaquin Valley during the
2013 DISCOVER-AQ campaign, Journal of Geophysical Research:
Atmospheres, 123, 4727-4745, doi:10.1029/2018JD028290.
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A literature search conducted by the EPA found ample evidence that
ammonia emissions may be underestimated in the San Joaquin Valley.\70\
Most studies compared air quality model results with satellite
retrievals; a few compared model results to measurements from aircraft.
All of the studies reviewed concluded that ammonia emissions are
underestimated by a factor of two to five. A factor of two is greater
than the 20-51 percent increase in total NOX emissions
estimated by Almaraz et al. (2018) and would more than offset the
effect of an increase in soil NOX on the sensitivity of
PM2.5 concentrations to ammonia reductions. These studies
collectively suggest that ammonia emissions are underestimated in the
San Joaquin Valley. In turn, that implies that model estimates of the
sensitivity in the precursor demonstration may be overestimated.
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\70\ Memorandum dated October 12, 2023, from Scott Bohning, EPA
Region IX, to Docket EPA-R09-OAR-2023-0263, Subject: ``Literature
search finds evidence that ammonia emissions are underestimated.''
---------------------------------------------------------------------------
Note that such an underestimate does not imply that the emissions
inventories in the SJV PM2.5 Plan do not meet the
requirements of CAA section 172(c)(3); rather it reflects that more
work is needed to continue to improve ammonia emissions estimates.
Studies may deduce that there is underestimation using a ``top down''
approach relying on ambient measurements or satellite observations; the
measurements reflect the atmospheric sum of the contribution of many
sources, possibly over an extended area. On the other hand, an
emissions inventory developed for regulatory purposes is typically a
``bottom-up'' estimate, derived from
[[Page 86591]]
compiling an inventory of stationary, area, mobile, and biogenic
sources, with their associated emissions factors and activity rates.
The emissions inventory is based on detailed knowledge and measurements
of specific source types under particular conditions. It is impractical
to measure every source under all environmental conditions or under all
possible variations, and to know the exact mix of source types and of
management practices in place. Thus, the emissions inventory depends on
the basic assumption that information compiled for the subset of
sources that it is practical to measure can be generalized to the full
population of sources in an area. Characterizing ammonia emissions from
the bottom up requires spatially and temporally resolved data, such as
detailed farming practices including irrigation and fertilizer
application, and how they affect emissions, which may vary depending on
multiple factors. Such detailed data may not be available except at an
enormous, impractical cost. A bottom-up emissions inventory may use the
best available data and techniques, yet not match estimates made via
top-down approaches. The discrepancy between the estimates from top-
down and bottom-up approaches indicates the need for further research
to better characterize the specific source types that contribute to the
total.
In 2021, CARB reported comparisons between its own model
predictions of ammonia to ambient data.\71\ The SJV PM2.5
Plan did not include an evaluation of model performance for ammonia per
se (just for particulate ammonium), but in a supplemental transmittal,
CARB described the results of two analyses confirming the likely
underestimation of ammonia. CARB compared CMAQ model predictions of
ammonia with the 2013 DISCOVER-AQ \72\ aircraft measurements and found
that near-ground ammonia was underpredicted by 50 percent at Fresno and
200 percent at Porterville. CARB also compared 2017 satellite
observations of ammonia from the Infrared Atmospheric Sounding
Interferometer to CMAQ model predictions and found that modeled ammonia
concentrations were half of the magnitude of the satellite retrievals
at some locations, and that the modeled average in the San Joaquin
Valley was about 25 percent less than observed. CARB also noted that
underprediction of ammonia would result in the modeled PM2.5
response to ammonia reductions being overpredicted.
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\71\ Email dated April 26, 2021, from Laura Carr, CARB, to Scott
Bohning, EPA Region IX, Subject: ``RE: Ammonia update,'' with
attachment ``Ammonia in San Joaquin Valley''.
\72\ DISCOVER-AQ: ``Deriving Information on Surface conditions
from COlumn and VERtically Resolved Observations Relevant to Air
Quality,'' https://science.nasa.gov/mission/discover-aq.
---------------------------------------------------------------------------
Finally, a third line of evidence supports the conclusion that
PM2.5 in the San Joaquin Valley is relatively insensitive to
ammonia reductions. Evidence from ambient data is especially strong
since it is independent of uncertainties in the emissions estimates and
the modeling exercises. Appendix G (``Precursor Demonstration'') of the
2018 PM2.5 Plan and Appendix C (``Weight of Evidence
Analysis'') of the CARB Staff Report on the 2018 PM2.5 Plan
\73\ describe previous research in support of the claim that ammonium
nitrate PM2.5 formation is NOX-limited rather
than ammonia-limited. That is, PM2.5 concentrations in the
San Joaquin Valley are expected to be sensitive to reductions in
NOX emissions but much less sensitive to reductions in
ammonia. Essentially, due to the abundance of ammonia, even with
ammonia emissions reductions there would still be enough available
ammonia to combine with NOX (in the form of nitric acid) to
form about the same amount of particulate ammonium nitrate. This was
the conclusion of Lurmann et al. (2006) \74\ based on ambient
measurements during the California Regional Particulate Air Quality
Study (CRPAQS), an intensive field study during winter 2000-2001.
Ammonia was almost always abundant relative to the amount of nitric
acid \75\ (derived from NOX and the immediate precursor to
particulate nitrate), so the authors concluded that ammonium nitrate
formation in the San Joaquin Valley was NOX-limited. This
conclusion was based on ambient data collected before the additional 60
percent reduction in NOX emissions that has occurred in the
interim, which would be expected to have increased the degree of
NOX-limitation (i.e., particulate ammonium nitrate formation
would be more limited by, and so more sensitive to, the amount of
NOX).
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\73\ CARB's ``Staff Report, Review of the San Joaquin Valley
2018 Plan for the 1997, 2006, and 2012 PM2.5 Standards,''
release date December 21, 2018.
\74\ Lurmann et al. (2006) Processes Influencing Secondary
Aerosol Formation in the San Joaquin Valley during Winter, Journal
of the Air & Waste Management Association, 56(12):1679-1693, doi:
10.1080/10473289.2006.10464573.
\75\ Nitric acid (HNO3) is formed from NOX
emissions; it combines with ammonium to form particulate ammonium
nitrate. The relative amounts of nitric acid and ammonium indicate
which is the limiting factor in ammonium nitrate formation.
---------------------------------------------------------------------------
Consistent with CRPAQS, aircraft-borne measurements during the more
recent 2013 DISCOVER-AQ \76\ study led CARB to a similar conclusion,
based on the large amount of ``excess ammonia''. This is defined as the
amount of measured ammonia left over if all the nitrate and sulfate
present combined with available ammonia to form particulate. The CARB
December 2018 Staff Report describes this in more detail,\77\ and also
lists results from multiple other recent studies with similar
conclusions. Two studies with chemical modeling,78 79 at
temperature and humidity levels typical for the San Joaquin Valley and
with ammonia and nitrate concentrations observed during DISCOVER-AQ,
showed that over 90 percent of the nitrate is present as particulate
rather than gas, consistent with abundance of ammonia and with low
sensitivity to ammonia changes. Two other studies, one using data from
DISCOVER-AQ \80\ and one using data from the 2010 CalNex field
campaign, \81\ found measured ammonia to be 50-100 times as abundant as
nitric acid, implying low sensitivity to ammonia emissions changes.\82\
In summary, the
[[Page 86592]]
ambient field study data that the EPA is aware of is consistent with a
conclusion that PM2.5 concentrations in the Valley are much
more sensitive to NOX emissions reductions than to ammonia
emissions reductions. This evidence is independent of the State's soil
NOX emissions estimate and is an important basis for the
EPA's determination that the responses to ammonia reductions for the
1997 annual PM2.5 NAAQS that are slightly above the
recommended contribution threshold are likely overestimated. Thus, the
ambient evidence supports the EPA's determination that ammonia does not
contribute significantly to PM2.5 levels above the 1997
annual PM2.5 NAAQS.
---------------------------------------------------------------------------
\76\ DISCOVER-AQ: ``Deriving Information on Surface conditions
from COlumn and VERtically Resolved Observations Relevant to Air
Quality,'' https://science.nasa.gov/mission/discover-aq.
\77\ CARB, ``Staff Report: Review of the San Joaquin Valley 2018
Plan for the 1997, 2006, and 2012 PM2.5 Standards,''
December 21, 2018, Appendix C, 12ff.; available at https://ww2.arb.ca.gov/resources/documents/2018-san-joaquin-valley-pm25-plan.
\78\ Id. at 12 (presenting CARB analysis of ammonia impacts in
the San Joaquin Valley).
\79\ Prabhakar et al. (2017) Observational assessment of the
role of nocturnal residual-layer chemistry in determining daytime
surface particulate nitrate concentrations, Atmospheric Chemistry
Physics, 17, 14747-14770. doi:10.5194/acp-17-14747-2017.
\80\ Parworth et al. (2017) Wintertime water-soluble aerosol
composition and particle water content in Fresno, California,
Journal of Geophysical Research, Atmosphere., 122, 3155-3170. doi:
10.1002/2016JD026173, p. 3165. (noting that ``The average mixing
ratio of NH3 was 49 times greater than HNO3 .
. . . These results highlight that NH3 was in excess, and
NH4NO3 [ammonium nitrate] formation is likely
limited by HNO3 availability in Fresno,'' i.e., about a
factor of 50).
\81\ CalNex, or California Research at the Nexus of Air Quality
and Climate Change, was a NOAA-sponsored field study during summer
2010; https://www.esrl.noaa.gov/csd/projects/calnex/. Markovic et
al., (2014), Measurements and modeling of the inorganic chemical
composition of fine particulate matter and associated precursor
gases in California's San Joaquin Valley during CalNex 2010, Journal
of Geophysical Research--Atmospheres, 119, 6853-6866, doi:10.1002/
2013JD021408, p. 6863 (noting that `` . . . the observed
NH3 (g) mixing ratios were elevated . . . the observed
HNO3 (g) mixing ratios were 2 orders of magnitude
lower,'' i.e., about a factor of 100).
\82\ The CARB December 2018 Staff Report explains (in Appendix
C, p. 14) that NOX is the limiting pollutant as shown by
this relative abundance of ammonia, but that the expected low
sensitivity to ammonia reductions does not mean zero response; the
reduction necessarily shifts nitrate from particulate to gas to
maintain chemical equilibrium. Thus, NOX being the
limited pollutant does not contradict the modeled responses to 30-70
percent reductions.
---------------------------------------------------------------------------
Comment 3.B.1: CCEJN's second concern with the precursor
demonstration relates to the State's conclusions regarding the level of
ammonia reductions that could be achieved through potential control
measures. The commenter asserts that ``. . . the state repeatedly uses
a lack of certainty about emission reduction potential to justify no
regulation at all.'' As an example, they argue that the State
acknowledges that research shows that ammonia emissions from manure-
based fertilizer can be reduced by 50-90 percent through quick mixing
or injection but that it declines to consider the measure feasible for
synthetic fertilizers merely because the State does not know how
effective it will be.
Response 3.B.1: We disagree with CCEJN's claim that the State
relies primarily on a lack of certainty about potential emissions
reductions to justify not regulating ammonia in the San Joaquin Valley.
Rather, the State based its decision not to regulate ammonia for
purposes of meeting the 1997 annual PM2.5 NAAQS on the
technical analyses it performed indicating that ammonia does not
contribute significantly to PM2.5 concentrations that exceed
the 1997 annual PM2.5 NAAQS.
Where the State identifies uncertainties about potential ammonia
emissions reductions, it does so in the context of its controls
analysis to support the ammonia precursor demonstration, which it
conducted at the request of the EPA and in accordance with EPA
guidance. As acknowledged by the commenter, under the PM2.5
SIP Requirements Rule, a state may submit an optional precursor
demonstration showing that a particular PM2.5 precursor
chemical species does not contribute significantly to PM2.5
levels above the standard in the area.\83\ If the EPA approves a
precursor demonstration for a particular chemical species, the state is
not required to control emissions of that precursor from existing
sources in the relevant attainment plan.\84\
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\83\ 81 FR 58010, 58021 (August 24, 2016); 40 CFR 51.1006
(``Optional PM2.5 precursor demonstrations'').
\84\ 40 CFR 51.1006(a)(1)(iii) and 51.1010(a)(2)(ii).
---------------------------------------------------------------------------
The EPA's July 2023 proposal includes a detailed summary of the
precursor demonstration in the SJV PM2.5 Plan and supporting
March 2023 Ammonia Supplement, and of the EPA's evaluation. We will not
reiterate all of the State's conclusions herein except to highlight the
key finding that modeled sensitivities for the 1997 annual
PM2.5 NAAQS of PM2.5 concentrations to a 30
percent ammonia reduction are approximately at or below the
contribution threshold used to determine significance. The
PM2.5 Precursor Guidance explains that in cases where the
PM2.5 response to a 30 percent reduction in precursor
emissions is close to the contribution threshold, the EPA may require
air agencies to identify and evaluate potential emissions controls in
support of a precursor demonstration that relies on a sensitivity
analysis. The response of ambient PM2.5 to an actual
assessment of the benefit from potential controls can be used to
determine whether controlling ammonia would significantly affect
PM2.5 levels. In accordance with 40 CFR 51.1010(a)(2)(ii),
the EPA required the State to provide an analysis of potential controls
to aid the EPA in its evaluation of the precursor demonstration. The
State provided such controls analysis in the March 2023 Ammonia
Supplement, which built upon information previously provided in the
2018 PM2.5 Plan.
As discussed in our proposal, the State's controls analysis
included a review of ammonia emissions reductions achieved nationwide
from 2011 to 2017, an evaluation of the main ammonia source categories
in the San Joaquin Valley, a summary of existing control measures in
the San Joaquin Valley that affect ammonia from these sources, a review
of existing control measures implemented by other air districts, and an
evaluation of additional mitigation options for ammonia sources in the
Valley.\85\ Based on the State's and District's analyses, they
determined that significant ammonia emissions reductions are already
being achieved by measures targeting VOC emissions and that the ammonia
reductions achievable from additional controls are well below 30
percent.
---------------------------------------------------------------------------
\85\ 88 FR 45276, 45288-45290.
---------------------------------------------------------------------------
In this action, we are finalizing our determination that the State
has provided adequate support for its conclusion that available
additional ammonia controls would yield less than a 30 percent
reduction in ammonia emissions. We are finding that the District made a
convincing case that significant ammonia reductions have already been
achieved through District Rule 4570 and that few additional mitigation
measures could provide only modest further reductions from confined
animal facilities (CAFs), which account for 58 percent of the total
ammonia inventory. Similarly, the State has provided support for its
assertion that additional reductions are not feasible from the
fertilizer, composting, and other smaller source categories through its
analysis of potential fertilizer controls and information regarding
controls that are already in place for these source categories. As
discussed in our proposal, we acknowledge the uncertainty in the
reductions that are currently being achieved from the fertilizer source
category but are finalizing our determination that even if ammonia
reductions could be reduced by a very high percentage, such reductions
added to the potential reductions from CAFs would amount to less than a
30 percent reduction in total ammonia emissions.
Given that the State's modeled sensitivities of PM2.5
concentrations to a 30 percent ammonia reduction are approximately at
or below the threshold used for identifying an impact that is
significant for the 1997 annual PM2.5 NAAQS, and that the
potential additional reductions would be well below 30 percent, the
response of PM2.5 to an ammonia reduction of a percentage
smaller than 30 percent would be below the contribution threshold,
indicating that ammonia does not contribute significantly to ambient
PM2.5 concentrations for purposes of the SJV
PM2.5 Plan for the 1997 annual PM2.5 NAAQS. Based
on these results, the State excluded ammonia controls from the SIP
submission. Because the EPA is finalizing approval of the State's
precursor demonstration as proposed, the State is not required to
regulate ammonia for purposes of meeting the CAA requirements for the
1997 annual PM2.5 NAAQS.
Regarding the example cited by the commenter of quickly mixing or
injecting fertilizer into the soil, we do not disagree that research
literature indicates that quick mixing or injection
[[Page 86593]]
can reduce ammonia emissions from manure-based fertilizer. The State
acknowledges in the March 2023 Technical Supplement that applying
manure to the soil surface without incorporation can lead to
significant ammonia emissions and includes an extensive discussion of
the various methods of incorporation as well as the related
requirements for injection and incorporation of manure-based fertilizer
in District Rule 4570. We disagree, however, with the commenter's
assertions that because the measure is effective at reducing ammonia
from manure-based fertilizers, the State should infer a similar
magnitude of effectiveness for synthetic fertilizers. The studies cited
by the commenter acknowledge uncertainties and highlight the importance
of additional research to adapt a potential measure to local
conditions.\86\ For example, Ti et al. (2019), in a global meta-
analysis of measures to reduce ammonia emissions from livestock and
cropping systems, found that the effects of fertilizer application
processes are highly dependent on crop type.\87\ The paper further
concludes that mitigation needs to be carefully planned and adapted to
local conditions because ammonia emissions are dependent on
environmental factors such as weather and soil conditions, that the
applicability of measures depends strongly on farm structures, and that
studies examining economic feasibility and the effects of combinations
of measures are needed.\88\ The State's March 2023 Ammonia Supplement
draws similar conclusions about the need for additional research to
assess the potential for ammonia emissions reductions, specifically as
they relate to quick mixing and injection, under conditions
representative of those in the San Joaquin Valley.\89\ Given these
uncertainties, we agree with the State's conclusion that additional
research is needed and find that the State's decision not to assign
ammonia reductions to such measure at this time to be reasonable.
---------------------------------------------------------------------------
\86\ Pan, B. et al. (2016). Ammonia volatilization from
synthetic fertilizers and its mitigation strategies: A global
synthesis. Agriculture, Ecosystems & Environment, Vol. 232, 283-289,
doi:10.1016/j.agee.2016.08.019; Ti, C. et al. (2019). Potential for
mitigating global agricultural ammonia emission: A meta-analysis.
Environmental Pollution, Vol. 245, 141-148, doi:10.1016/
j.envpol.2018.10.124.
\87\ Ti et al. (2019) op cit., p. 146. For example, the paper
notes that the effects of fertilizer application practices on
reducing ammonia emissions from vegetable production are lower than
in wheat and fruit production due in part to the smaller reduction
in ammonia emissions from vegetable fields associated with more
intensive irrigation.
\88\ Id. at 147.
\89\ March 2023 Ammonia Supplement, p. 94.
---------------------------------------------------------------------------
In addition to helping to resolve the uncertainties related to the
effectiveness of mitigation measures, additional research would also be
beneficial for improving understanding of any potential disbenefits
that may be specific to the area. The commenter appears to acknowledge
the potential for disbenefits in a footnote to their comment, which
notes that CCEJN does not endorse any specific approach for reducing
ammonia emissions, including quick mixing or injection, and that
``regulation of ammonia emissions cannot be permitted to exacerbate
degradation of groundwater quality.'' These expressed concerns about
the potential for adverse effects on water quality seem to align with
the State's position that more research is needed. Such research may
also inform other important considerations, such as the effects on
greenhouse gas emissions.
Comment 3.B.2: CCEJN asserts that the State's evaluation of
emissions from fertilizers is limited in that it is seemingly based on
just two studies, and does not consider additional mitigation options
identified in the literature such as using non-urea based fertilizers;
using controlled release fertilizers; using fertilizers with
nitrification inhibitors; irrigating immediately after fertilizer
placement; or adding amendments to fertilizers, such as zeolite,
pyrite, or organic acids. The commenter also points to a study on the
field of precision agriculture as a resource on mechanisms to minimize
fertilizer use,\90\ as well as two studies examining how modeling can
be used to predict ammonia volatilization, claiming that such studies
undermine the State's position that emissions reductions cannot be
calculated.\91\
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\90\ Association of Equipment Manufacturers, The Environmental
Benefits of Precision Agriculture in the United States, https://newsroom.aem.org/download/977839/environmentalbenefitsofprecisionagriculture-2.pdf.
\91\ Gurung, R.B. et al. (2021) Modeling ammonia volatilization
from urea application to agricultural soils in the DayCent model.
Nutr Cycl Agroecosyst, 119, 259-273. doi:10.1007/s10705-021-10122-z;
Yang, Y. et al. (2022) Comprehensive quantification of global
cropland ammonia emissions and potential abatement. Science of The
Total Environment, 812, 151450, doi:10.1016/j.scitotenv.2021.151450.
---------------------------------------------------------------------------
Response 3.B.2: We disagree with CCEJN's characterization of the
State's analysis of emissions from fertilizer as ``extremely narrow.''
We infer that the commenter is referring to the State's analyses for
synthetic fertilizer specifically, based on the numerous studies cited
in the State's discussion of manure application-related measures,\92\
and the commenter's assertion that the State's evaluation of
fertilizers is seemingly based on the findings from just two studies
and that Table 13 of the March 2023 Ammonia Supplement lists references
for Guthrie et al. (2018) \93\ and Eory et al. (2016) only.\94\
However, we note that both Guthrie et al. (2018) and Eory et al. (2016)
are compilation studies covering a range of mitigation options for
organic and synthetic fertilizer application and that the State's March
2023 Ammonia Supplement cites numerous studies in addition to these two
compilation studies. Furthermore, the State turned to the research
literature only after reviewing how other California State agencies are
engaged in fertilizer use and attempting to identify any existing rules
or regulations in the nation controlling ammonia emissions from this
source category.
---------------------------------------------------------------------------
\92\ E.g., see March 2023 Ammonia Supplement pp. 74-75.
\93\ Guthrie, S. et al. (2018). Impact of ammonia emissions from
agriculture on biodiversity: An evidence synthesis. Rand Europe, The
Royal Society. https://www.rand.org/pubs/research_reports/RR2695.html.
\94\ Eory, V. et al. (2016) ClimateXChange, On-farm technologies
for the reduction of greenhouse gas emissions in Scotland. https://www.climatexchange.org.uk/media/1927/on-farm_technology_report.pdf.
---------------------------------------------------------------------------
Regarding the additional mitigation options identified by CCEJN, we
appreciate that the commenter raises these potential strategies. We
acknowledge the studies cited by the commenter finding that
implementation of some of these strategies may help minimize ammonia
emissions from agricultural systems around the globe. We encourage CARB
and the District to keep abreast of research examining mitigation
options for minimizing ammonia emissions from fertilizer application in
support of future policy and management decisions, particularly as they
may relate to reducing PM2.5 exposure in the San Joaquin
Valley. However, as discussed in the following paragraphs, in light of
the absence of any SIP-approved requirements elsewhere in the nation,
the regulations adopted by other California State agencies to control
fertilizer application, and the uncertainties discussed in the studies
cited by CARB and the commenters, the EPA continues to agree with the
State's overall conclusions that more research is needed on potential
mitigation measures to reduce ammonia emissions from fertilizer
application in the San Joaquin Valley. We also agree that based on the
information currently available, the additional reductions achievable
are sufficiently low that the PM2.5 response to such
reduction would
[[Page 86594]]
be below the contribution threshold, indicating that ammonia does not
contribute significantly to ambient PM2.5 concentrations for
purposes of the SJV PM2.5 Plan for the 1997 annual
PM2.5 NAAQS. As we emphasized in our proposal, this finding
is specific to the facts and circumstances of this particular plan and
does not pre-determine the outcome of significance determinations of
precursors in the future.
In the March 2023 Ammonia Supplement, the State describes its
efforts to identify any SIP-approved requirements limiting ammonia
emissions from fertilizers that are being implemented in any other
areas of the United States and explains that it has not identified any
rules or regulations being implemented elsewhere. Thus, it describes
regulations in place adopted by other California State agencies to
control fertilizer application and its review of research studies
examining techniques for reducing ammonia emissions from synthetic
fertilizer application.
The State describes in Appendix C (``Stationary Source Control
Measure Analyses'') of the 2018 PM2.5 Plan and in the March
2023 Ammonia Supplement the various State agencies responsible for
ensuring environmentally safe use of fertilizer material. It describes
requirements for commercial irrigated lands in the San Joaquin Valley
to prepare a farm management plan (including an irrigation nitrogen
management plan) that complies with waste discharge requirements in
accordance with the Central Valley Irrigated Lands Regulatory Program
established by the California State Water Resources Control Board. The
nitrogen management plan is designed to ensure that the amount of
nitrogen applied to agricultural lands is in reasonable balance with
the needs of crops that are being grown. The State explains that the
``4 R's'' of nitrogen management (``Right source'' of nitrogen at the
``right rate,'' ``right time,'' and ``right place'') \95\ serve as
guiding nitrogen efficiencies principles that growers are recommended
to follow when developing their management plans, and that growers are
required to employ enhanced strategies if it is determined that they
are not optimizing fertilizer use, as determined by the fraction of
nitrogen applied to nitrogen used.
---------------------------------------------------------------------------
\95\ March 2023 Ammonia Supplement, p. 92.
---------------------------------------------------------------------------
Next, CARB discusses measures identified in the literature for
reducing ammonia emissions from fertilizer application, which include
optimizing fertilizer use, adding a urease inhibitor, mixing and
injecting fertilizer into the soil quickly, and applying fertilizer
during optimal weather conditions. Based on its review, the State finds
that several of the strategies align with the 4 R's of nitrogen
management but that more research is needed to determine the
feasibility and effectiveness of such strategies in California due to
the unique climate conditions and farming practices in the San Joaquin
Valley, and to explore any potential adverse consequences. CARB cites
studies linking weather conditions with ammonia emissions,\96\ and
states that it is unclear which environmental factors are the most
important for different fertilizer types.
---------------------------------------------------------------------------
\96\ Venterea, R.T. et al. (2012) Challenges and opportunities
for mitigating nitrous oxide emissions from fertilized cropping
systems. Frontiers in Ecology and the Environment, 10:10, 562-570.
doi:10.1890/120062; Grahmann, K., et al. (2013) Nitrogen use
efficiency and optimization of nitrogen fertilization in
conservation agriculture. Cabi Reviews, 8:053. doi:10.1079/
PAVSNNR20138053.
---------------------------------------------------------------------------
As discussed in Response 3.B.1, the studies cited by CCEJN
similarly highlight the need for additional research to examine how the
potential for ammonia emissions reductions varies with local
conditions. These studies largely focused on the United Kingdom or were
global in scale and none of them appear to address mitigation
potentials in the western United States or San Joaquin Valley
specifically. Thus, none of the studies reflect climate conditions or
farming practices in the San Joaquin Valley, and likely also do not
reflect efficiencies already achieved through local regulations in the
Valley. Furthermore, several of the studies suggest that some of the
measures have already been adopted in many areas, adding to the
uncertainty about whether and where there are opportunities for
significant reductions in ammonia. For example, Pan et al. (2016),
notes that ``[e]nhanced efficiency fertilizers have been widely adopted
to minimize N[itrogen] loss, including NH3 volatilization
from agricultural systems.'' \97\ Similarly, Gu et al. (2023), in a
study examining the potential to mitigate nitrogen pollution from
global cropland, concluded that the largest reduction of reactive
nitrogen input and losses available were in East and South Asia and
Southeast Asia, which they attribute to an overuse of fertilizer in
those areas.\98\ They calculated a much lower reduction potential in
the European Union, Australia, and North America, where they concluded
that nitrogen use in croplands is ``closer to the estimated optimal
level.''
---------------------------------------------------------------------------
\97\ Pan et al. (2016) op. cit., p. 288.
\98\ Gu, B. et al. (2023) Cost-effective mitigation of nitrogen
pollution from global croplands. Nature, Vol. 613, pp. 77-84.
---------------------------------------------------------------------------
In addition to the uncertainty in emissions reduction potentials,
we note that studies suggest that one of the five mitigation options
identified by CCEJN, using fertilizers with nitrification inhibitors,
may lead to an increase in ammonia emissions. For example, Pan et al.
(2016) noted that ``[a]lthough nitrification inhibitors are designed to
target N2O emissions, the use of these inhibitors may
prolong the retention of NH4 in the soil resulting in
[ammonia] volatilization (Kim et al., 2012; Lam et al., 2016; Ni et
al., 2014).'' \99\ Pan et al. (2016) concluded that nitrification
inhibitors increase ammonia volatilization by 38.0 percent.\100\
Similarly, Ti et al. (2019) found that nitrification inhibitors
increased ammonia emissions by 42.6 percent,\101\ whereas Newell Price
et al. (2011) found that ``[ammonia] emissions to air and ammonium/
nitrite losses to water may be increased by a small amount.'' \102\
While studies specific the San Joaquin Valley may show different
results, based on the studies cited by the commenter, the research
currently available does not indicate that use of fertilizers with
nitrification inhibitors would reduce ammonia emissions in the San
Joaquin Valley.
---------------------------------------------------------------------------
\99\ Pan et al. (2016) op. cit., p. 284.
\100\ Id. at p. 286.
\101\ Ti et al. (2019) op. cit., p. 143.
\102\ J. Newell Price, et al., (2011) An inventory of mitigation
methods and guide to their effects on diffuse water pollution,
greenhouse gas emissions and ammonia emissions from agriculture
(Defra Project WQ0106). https://randd.defra.gov.uk/Document.aspx?Document=MitigationMethodsUserGuideDecember2011FINAL.pdf, p. 52.
---------------------------------------------------------------------------
The studies that CCEJN points to on precision agriculture also note
wide adoption of such practices while acknowledging some potential for
additional environmental benefits. For example, in a 2021 report on the
benefits of precision agriculture in the United States, the Association
of Equipment Manufacturers discusses environmental improvements that
have already been achieved through adoption of precision agriculture
technologies.\103\ Whitmore (2019) notes that larger farms have been
quicker to adopt precision agriculture techniques due to greater
resources,\104\ and Lowenberg-Deboer
[[Page 86595]]
and Erickson (2019) note that ``[t]he biggest gap in [precision
agriculture] adoption is for medium and small farms in the developing
world that do not use motorized mechanization,'' which they attribute
to cost-effectiveness challenges.\105\ Lowenberg-Deboer and Erickson
(2019) also highlight the perception that adoption of precision
agriculture has been slow, but state that ``[s]ome aspects of
[precision agriculture] were adopted as quickly and as widely as any
technology in history, while others have lagged behind for technical
and economic reasons.'' \106\
---------------------------------------------------------------------------
\103\ Association of Equipment Manufacturers, The Environmental
Benefits of Precision Agriculture in the United States, https://newsroom.aem.org/download/977839/environmentalbenefitsofprecisionagriculture-2.pdf.
\104\ Whitmore J. (2019) Precision Farming Comes into Its Own,
Mich. St. Univ., https://www.canr.msu.edu/news/precision-farming-comes-into-its-own.
\105\ Lowenberg-DeBoer, J. and Erickson, B. (2019) Setting the
Record Straight on Precision Agriculture Adoption, Agronomy J., p.
1565.
\106\ Id. at 1552.
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Taken together, the EPA finds that the studies cited by CCEJN
highlight the uncertainties in the feasibility of the measures
identified in its comment letter and suggest that more research is
needed to estimate the additional reductions achievable in the San
Joaquin Valley. Furthermore, while several studies suggest that there
may be the potential for additional ammonia reductions from synthetic
fertilizer application, they also indicate that such potential is not
quantifiable with the information available at this time and may be
lower in the San Joaquin Valley than in other locations around the
globe.
Finally, regarding CCEJN's comment about the availability of
modeling to predict ammonia volatilization, we acknowledge these
additional studies \107\ identified by the commenter describing models
for estimating ammonia emissions. However, we disagree with the
commenter that the output from these models compel certain policy
decisions in the San Joaquin Valley at this time. Here again the
commenter cites large-scale studies that do not reflect model
performance under conditions representative of those in the Valley.
Both studies cited by the commenter note uncertainties due to crop
type, meteorological conditions, and other factors, suggesting that
research specific to the climate and farming practices in the Valley is
needed. Furthermore, it is not clear that the models discussed in the
studies are ripe for application in a regulatory context. For example,
Gurung et al. (2021) concludes that additional research is needed
before the models could be used to evaluate policy decisions for
mitigating ammonia emissions from soils:
---------------------------------------------------------------------------
\107\ Gurung et al. (2021) op. cit.; Yang et al. (2022) op. cit.
In future research, DayCent can also be used to test ``what if''
scenarios for identifying best management practices (BMPs) given
variation in the soil and climatic conditions. These scenarios could
focus on adopting the 4R nutrient stewardship principles and
identifying regional level BMPs associated with the addition of urea
fertilization. Further model improvement would also allow for a
broader set of options to be evaluated in support of policy and
management decisions associated with mitigating of NH3
---------------------------------------------------------------------------
volatilization from agricultural soils.
Thus, based on our review, we find the State's conclusions that
further research is needed to explore ammonia reduction potentials in
the San Joaquin Valley to be reasonable. We encourage the State and
District to perform and keep abreast of research on quantifying the
effects of mitigation measures on ammonia emissions and their
implications for policy and management decisions.
Comment 3.B.3: CCEJN asserts that the State dismisses controls for
fertilizers on the basis that there is no published literature on
control effectiveness in the San Joaquin Valley specifically. The
commenter contends that such justification is ``sometimes absurd'' and
that it cannot be true that studies specific to the Valley are
necessary to determine that minimizing the use of fertilizer will
decrease ammonia emissions. The commenter asserts that ``this bar for
effectiveness makes meaningful regulation impossible, particularly when
the state disincentivizes research in the Central Valley by insisting
that ammonia need not be regulated.'' The commenter further notes that
it is unfortunate that the State never mentions conducting any studies
in the San Joaquin Valley.
Response 3.B.3: We disagree with CCEJN that the State claims that
studies specific to the Valley are needed to discern that reducing
fertilizer use will reduce ammonia emissions. In the 2018
PM2.5 Plan, the State discusses the link between fertilizer
application and both ammonia emissions and nitrate contamination in
groundwater, and describes current State regulations aimed at
optimizing fertilizer use to minimize emissions of ammonia to the
atmosphere.\108\ Additionally, in its discussion of optimizing or
minimizing fertilizer use in the 2023 Ammonia Supplement, the State
discuss the ``4 R's'' of nitrogen management (i.e., ``applying the
`Right source' of nitrogen at the `Right rate,' `Right time,' and
`Right place' '') and that minimizing fertilizer use is consistent with
the right rate principle. CARB also notes that Guthrie et al. (2018)
describes that minimizing the application of fertilizer to a level
commensurate with optimal crop production can reduce ammonia
emissions.\109\ Thus, the State does acknowledge the potential benefits
of minimizing fertilizer use on ammonia emissions. Where the State
concludes that additional research is needed is in the context of how
optimal fertilizer use can be achieved, which it notes is ``not well
described by both Guthrie et al. (2018) and the publications they
referenced, nor were any specific regulations identified.'' Given that
some level of reduction is already being achieved through existing
regulations and current practices, and the importance of careful
consideration of environmental factors for optimizing fertilizer use,
we find the State's conclusion that additional research specific to the
warm, dry climate conditions of the San Joaquin Valley is needed to
determine whether additional strategies could further optimize
fertilizer use and reduce ammonia emissions to be reasonable.
---------------------------------------------------------------------------
\108\ 2018 PM2.5 Plan, Appendix C, pp. C-339 to C-
341.
\109\ March 2023 Ammonia Supplement, p. 92.
---------------------------------------------------------------------------
Regarding CCEJN's statement that the State dismisses controls for
fertilizers based on a lack of information on control effectiveness in
the Valley, as discussed in Responses 3.B.1 and 3.B.2, studies reviewed
by the State, as well as studies cited by the commenter, emphasize that
strategies to reduce ammonia emissions are highly dependent on local
environmental factors and farm structures, and that more research is
needed to examine these factors, as well as the effects of combinations
of measures. The State concludes that specific mitigation strategies
identified in the literature, such as optimizing fertilizer use, are
already being implemented in the San Joaquin Valley because of
regulations adopted by other California State agencies and co-benefits
such as reduced cost to farmers. Based on the literature study findings
regarding the importance of local information and the need to examine
combinations of measures, the absence of existing rules or regulations
in other areas controlling ammonia emissions directly, and the State's
evaluation of the mitigation strategies already implemented through
regulation by other State agencies, we maintain that it is reasonable
that the State concludes that more research specific to the Valley is
needed to assess the feasibility and effectiveness of additional
measures for synthetic fertilizers.
We also disagree with CCEJN's assertions that needing additional
studies specific to the conditions in the
[[Page 86596]]
Valley makes meaningful regulation impossible and that the State
disincentivizes research by concluding ammonia does not need to be
regulated. Contrary to the commenter's claim that the State does not
discuss any studies that it is conducting to assess the effectiveness
of ammonia controls in the Valley, the State does include a discussion
of recent and ongoing and research in Section 4 of the March 2023
Ammonia Supplement. CARB's work includes the development of a mobile
measurement platform equipped with an ammonia monitor and other
instrumentation to examine ammonia sources. The State notes that in
fall 2018, CARB collaborated with researchers from the University of
California, Davis to measure ammonia and other air pollutants near
dairies in the San Joaquin Valley to evaluate the effectiveness of
alternative manure management practices.\110\ The State also mentions
additional research to evaluate emissions from dairies, to use
satellite and remote sensing data to evaluate ammonia emissions sources
across the Valley, and to identify opportunities to reduce ammonia and
other pollutant emissions from dairy manure lagoons specifically. These
efforts may inform future decision-making regarding the regulation of
ammonia in the San Joaquin Valley.
---------------------------------------------------------------------------
\110\ March 2023 Ammonia Supplement, Figure 5 (showing that
dairy cattle account for an estimated 67.2 percent of ammonia
emissions from CAFs).
---------------------------------------------------------------------------
Moreover, the EPA's action herein to approve the precursor
demonstration in the SJV PM2.5 Plan for the 1997 annual
PM2.5 NAAQS does not preclude the State from adopting
controls for ammonia in the future. As discussed in our proposal, a
consequence of this final action to approve the State's ammonia
precursor demonstration is that the State is not required to implement
BACM/BACT level controls for sources of ammonia for purposes of the SJV
PM2.5 Plan for 1997 annual PM2.5 NAAQS. Under 40
CFR 51.1006(b), such precursor demonstration approval applies only to
the SJV PM2.5 Plan that is the subject of this final action.
For any new PM2.5 attainment plan that the State is required
to submit in accordance with 40 CFR 51.1003 for purposes of any
PM2.5 NAAQS, the EPA may determine that ammonia contributes
significantly to PM2.5 levels that exceed the NAAQS and that
the State is required to implement controls for sources of ammonia for
purposes of such attainment plan.
Comment 3.B.4: Regarding the District's current rules, CCEJN
asserts that the State assumes that farmers are already adopting the
most efficient practices (e.g., feeding the most efficient amount of
protein, incorporating manure quickly) but ``provides little support
for these assumptions, even though it is well established that farmers
do not always adopt the most efficient practices.'' The commenter
proposes that the precursor analysis should err on maintaining the
presumption that precursors should be regulated and thereby err on the
side of high estimates of potential effectiveness and that because the
State does not do so, its analysis is arbitrary and capricious. The
commenter asserts that the State relies on ``biased assumptions,''
assuming low potential effectiveness from measures not being
implemented, high reductions from Rule 4570, and that making optional
measures mandatory would have no impact. The commenter further contends
that if Rule 4570 is effective, the State should make its most
effective requirements mandatory where feasible and possibly increase
the stringency, and that the EPA should require the State to conduct
further analysis of the rule.
Response 3.B.4: We disagree with CCEJN's assertions that the State
provides little support for its estimates of ammonia reductions that
have been achieved by existing regulations and that the assumptions it
makes to arrive at those estimates are biased. As discussed in our
proposal, the District discusses in detail in Appendix C of the 2018
PM2.5 Plan how Rule 4570 is structured, the control menu
requirements for each of the CAF operations/sources, and research
papers that support its estimates of ammonia emissions reductions from
the measures.\111\ As the District explains, some of the measures in
Rule 4570 are required to be implemented but the rule also requires
that additional measures be selected from a menu of options. The menu-
based approach was developed to allow facilities flexibility to select
measures that are the most practical and effective for their design and
operation.\112\
---------------------------------------------------------------------------
\111\ 2018 PM2.5 Plan, Appendix C, pp. C-312 to C-
323.
\112\ Id.; March 2023 Ammonia Supplement, pp. 25-26.
---------------------------------------------------------------------------
For those measures that are required to be selected from a menu of
options, the District presents its rationale in Appendix C of the 2018
PM2.5 Plan and Appendix F of the staff report for Rule 4570
for its assumptions about which measure a farmer will select and the
resulting effects on ammonia emissions.\113\ The District references
research studies to support many of its assumptions, and where there is
greater uncertainty about which measures may be selected or the
corresponding ammonia reductions that can be achieved, the District
explains how its assumptions are conservative. CCEJN has not provided
any evidence to refute the District's analysis or conclusions.
Therefore, based on the information presented, the EPA believes that
the District relied on its expertise and the best information available
and applied that information reasonably.
---------------------------------------------------------------------------
\113\ 2018 PM2.5 Plan, Appendix C, pp. C-311 to C-
323; SJVUAPCD, ``Final Draft Staff Report, Proposed Re-Adoption of
Rule 4570 (Confined Animal Facilities),'' June 18, 2009, at Appendix
F, ``Ammonia Reductions Analysis for Proposed Rule 4570 (Confined
Animal Facilities),'' June 15, 2006 (discussing various assumptions
underlying the District's calculation of ammonia emissions factors).
---------------------------------------------------------------------------
Regarding CCEJN's statement that the State should err on the side
of high estimates of potential reductions from additional measures,
given the uncertainties discussed in Responses 3.B.1 and 3.B.2, we find
that the potential emissions reductions achievable in the San Joaquin
Valley from many of the measures are not quantifiable at this time and
that the State drew reasonable conclusions based on the information it
evaluated. While the EPA appreciates that the commenter raises
additional research studies not identified by the State in its
analysis, as discussed in Responses 3.B.1 and 3.B.2, we have reviewed
the studies and find that they do not contradict the State's
conclusions. Thus, we find that the State's analysis of potential
ammonia emissions reductions is neither arbitrary nor capricious.
We also find that CCEJN's claim that it is well-established that
farmers do not adopt the most efficient practices is not well
supported. To back this claim, the commenter cites two studies
discussing the rates of adoption of precision agriculture
technologies.\114\ However, these studies do not appear to indicate any
reluctance on the part of farmers to adopt the most efficient
practices. As discussed in Response 3.B.2, these papers discuss
widespread adoption of precision agriculture technology while also
acknowledging areas where there are opportunities for increased
adoption, such as for specific crop types or farm sizes and for
specific precision agriculture technologies, such as variable rate
technology.\115\ Where
[[Page 86597]]
adoption has been slower, the studies point to feasibility constraints
and the need for more research. For example, Lowenberg-DeBoer and
Erickson (2019) emphasize that precision agriculture has been widely
adopted and that in cases where technologies have been adopted at a
slower pace, the authors attribute it to technological and economic
feasibility challenges.\116\ The study authors also note that the
studies they reviewed hypothesize that more reliable decision rules
that account for the effects of moisture, temperature, soil organic
matter, and other factors on nitrogen response may be needed to
increase variable rate technology adoption.\117\ Whitmore (2019)
similarly notes the complexity and high cost of new equipment as
barriers to wider adoption of precision technology.\118\ CCEJN does not
provide any evidence related to other measures in its letter or other
measures in the State's analysis to support its claim.
---------------------------------------------------------------------------
\114\ Whitmore (2019) op. cit.; Lowenberg-DeBoer and Erickson
(2019) op. cit.
\115\ Variable rate technology refers to the use of data and
automation to optimize application of fertilizer, soil amendments,
seed, or plant protection chemicals to optimize crop performance,
save time and money, and reduce environmental impacts.
\116\ Lowenberg-DeBoer and Erickson (2019) op. cit., p. 1552.
\117\ Id. at 1564-1565.
\118\ Whitmore (2019) op. cit.
---------------------------------------------------------------------------
Finally, we disagree with CCEJN's assertion that if Rule 4570 is
effective, the State must consider making its optional requirements
mandatory. As discussed earlier in this response, if the EPA approves a
state's precursor demonstration showing that a particular
PM2.5 precursor chemical species does not contribute
significantly to PM2.5 levels above the standard in the
area, the state is relieved of the obligation to control emissions of
that precursor from existing sources in the relevant attainment plan.
Comment 3.C: Regarding the State's reliance on 2024 modeling
results for its precursor analysis, CCEJN asserts that the State should
not have relied on modeling of 2024, which is after the 2023 attainment
deadline, and which nevertheless shows ammonia contributions that are
above the contribution threshold. CCEJN further asserts that the use of
2024 modeling ``violates the Act in three ways.''
First, the commenter asserts that the approach ignores the
requirement to demonstrate attainment as expeditiously as practicable
because it does not consider ammonia reductions that may have resulted
in attainment before 2023. They note that the State claimed it was
close to attaining in 2020 and that meaningful reductions in ammonia
would have most likely resulted in attainment earlier (i.e., in 2021 or
2022).
Second, the commenter notes that the State relies not only on a
future year but a year after the attainment deadline. Because
NOX emissions are expected to be lower in 2024 than 2023,
the commenter suggests that the impacts of ammonia reductions would be
less in 2024 than in 2023 and that the impacts of ammonia reductions in
2023 are unknown. The commenter also claims that the EPA makes
assumptions about how the State conducted its analysis and recommends
that the EPA seek clarification from the State about whether the
analysis relied on emissions projected from baseline (i.e., existing)
control measures or baseline measures plus measures committed to in the
plan. If the State did not conduct the analysis ``with numbers that are
comparable to what are expected in 2023,'' the commenter contends that
the EPA must require the State to redo the analysis.
Third, CCEJN asserts that the State's model indicating a design
value of 12.03 [micro]g/m\3\ cannot accurately describe 2023 conditions
given that 2022 data show a design value well above 16 [micro]g/m\3\.
They conclude that the ``EPA's approval of a precursor analysis that
relies on such unrealistic modeling is therefore arbitrary and
capricious and contrary to law.''
Response 3.C: While the State relied on 2024 modeled sensitivities
of PM2.5 to ammonia reductions, it is important to note that
the EPA also considered the 2023 model responses via a NOX-
based interpolation between the State's model results for 2020 and
2024. The highest estimated response was at the Hanford site, 0.26
[micro]g/m\3\ for 2024 and 0.27 [micro]g/m\3\ for 2023, and did not
change the EPA's conclusions regarding the ammonia precursor
demonstration.\119\ In determining that ammonia does not contribute
significantly in the San Joaquin Valley despite the Hanford response
being above the 0.25 [micro]g/m\3\ contribution threshold that the
State derived for the 1997 annual PM2.5 NAAQS, we continue
to rely on the abundant ambient evidence of excess ammonia relative to
NOX. This evidence includes evidence specific to the Hanford
area, where mobile laboratory observations during the DISCOVER-AQ study
showed ambient concentrations of ammonia that were approximately five
times higher than those that were modeled.\120\ These factors led the
EPA to conclude that the model responses were likely overestimated and
did not represent a significant contribution of ammonia to
PM2.5 levels.
---------------------------------------------------------------------------
\119\ 88 FR 45276, 45293, fn. 184.
\120\ Kelly, J.T. et al. (2018), op. cit.
---------------------------------------------------------------------------
We further disagree with the commenter's assertion that the State's
approach ignores the requirement for expeditious attainment. The CAA
requirement for expeditious attainment is not directly relevant for
evaluating a precursor demonstration, which is mainly concerned with
whether PM2.5 in the atmosphere is sensitive to emissions
reductions of the precursor. For that purpose, the PM2.5
Precursor Demonstration Guidance provides for the use of modeled
sensitivities of PM2.5 to a reduction in precursor emissions
evaluated in the base year or a future year, noting that there are many
considerations in choosing the appropriate year to model.\121\ The key
factor for the State's use of a future year was the fact that sizable
NOX emissions reductions were projected to occur over time
and would change the atmospheric chemistry in the San Joaquin Valley.
The reductions are mainly due to the existing motor vehicle control
program and would occur independent of any controls in, or EPA action
on, the Plan.\122\ The sensitivity of PM2.5 concentrations
to ammonia reductions decreases with decreasing NOX
emissions. Between 2020 and 2024, the modeled response to a 30 percent
ammonia emissions reduction declines by 50 percent at the design value
monitoring site, Bakersfield-Planz, from 0.24 [micro]g/m\3\ down to
0.12 [micro]g/m\3\. (The corresponding decline is 37 percent for the
average over all monitoring sites.) Thus, much of the benefit of
ammonia controls applied in 2020 would be lost by 2023 and 2024.
---------------------------------------------------------------------------
\121\ PM2.5 Precursor Demonstration Guidance, p. 36.
\122\ 2018 PM2.5 Plan, Appendix B. NOX
emissions decrease 27 percent between 2020 and 2024 due to baseline
measures.
---------------------------------------------------------------------------
With regard to whether ammonia emissions reductions could have
resulted in earlier attainment, the EPA used results from the Plan's
attainment demonstration to assess the effect of a 30 percent ammonia
reduction in 2022 and found that it would not have resulted in
attainment in that year.\123\ We estimated the 2022 design value as
15.4 [micro]g/m\3\ by using a NOX emissions-based
interpolation between the Plan's 2018 and 2023 design values, 16.3 and
14.7 [micro]g/m\3\, respectively.\124\ Similarly we estimated the 2022
sensitivity to ammonia from the State's modeled sensitivities for 2020
and 2024. Applying a 30 percent ammonia reduction for 2022 resulted in
a design value of 15.2 [micro]g/m\3\, which is above the level of the
1997 annual PM2.5 NAAQS
[[Page 86598]]
(i.e., 15.0 [micro]g/m\3\). Thus, we conclude that ammonia emissions
reductions would not have resulted in attainment before the Plan's
projected 2023 attainment date.
---------------------------------------------------------------------------
\123\ Spreadsheet ``Estimated 2023 annual PM2.5
ammonia sensitivity and 2022 DV.xlsx,'' ``2023 vs. 2024 response to
30% ammonia reduction,'' EPA Region IX, October 20, 2023.
\124\ 15 [micro]g/m\3\ SIP Revision, Appendix K, Table 33.
---------------------------------------------------------------------------
Regarding the use of 2024 modeled sensitivities in lieu of modeled
sensitivities for 2023, the EPA finds that our conclusions would be the
same for the purposes of our evaluation of the precursor demonstration.
We estimated 2023 responses to ammonia emissions reductions by
interpolating between the responses for available 2020 and 2024
modeling; the interpolation used projected NOX emissions for
2020, 2023, and 2024 and found the estimated 2023 response to be only
0.01 [micro]g/m\3\ higher than in 2024.\125\ While there are several
differences between 2020 and 2024 modeled emissions for the various
PM2.5 precursors and direct PM2.5, the key
difference for assessing the change in the sensitivity of
PM2.5 to ammonia reductions is NOX emissions
levels. The modeling for 2020 and 2024 represent PM2.5
design values for the NOX emissions levels in 2020 and 2024,
and their respective responses to a 30 percent ammonia emissions
reduction. To estimate the PM2.5 response to ammonia
reductions in other years or for other control scenarios, only the
NOX emissions level is needed. The estimate does not depend
on NOX emissions differences between 2023 and 2024
calculated for baseline, controlled, or other scenarios, only on the
resulting 2023 emissions level being evaluated.
---------------------------------------------------------------------------
\125\ Spreadsheet ``Estimated 2023 annual PM2.5
ammonia sensitivity and 2022 DV.xlsx,'' ``Whether 30% ammonia
reduction could attain early,'' EPA Region IX, October 20, 2023.
---------------------------------------------------------------------------
The commenter states that it is unclear whether the precursor
demonstration analysis relied on a baseline emissions inventory, or an
inventory considering the controls in the plan. While this is not
documented prominently in the submittal materials, the precursor
demonstration modeling performed by the State used baseline
projections,\126\ that is, emissions expected with existing control
measures and without new control measures from the 2018
PM2.5 Plan or the 15 [micro]g/m\3\ SIP Revision.\127\
Notably, the EPA's conclusions for the precursor demonstration do not
depend on which of the two inventories is used. For the interpolation
to 2023, the EPA relied on controlled NOX emissions levels
(150.6 tpd) to estimate the 2023 response to 30 percent reduction to be
0.265 [micro]g/m\3\ (reported as 0.27 [micro]g/m\3\). Using baseline
NOX emissions (153.6 tpd), the estimated 2023 response is
0.275 [micro]g/m\3\, which is about 0.01 [micro]g/m\3\ higher. Thus,
the difference between using the baseline or controlled emissions for
assessing the sensitivity to ammonia emissions reductions is
negligible.
---------------------------------------------------------------------------
\126\ 2018 PM2.5 Plan, Appendix K, Section 5.6
``PM2.5 Precursor Sensitivity Analysis'', p. 70: ``To
evaluate the impact of reducing emissions of different
PM2.5 precursors on PM2.5 DVs, a series of
model sensitivity simulations were performed, for which
anthropogenic emissions of the precursor species were reduced by a
certain percentage from the baseline emissions;'' email dated
September 19, 2019, from Jeremy Avise, CARB, to Scott Bohning, EPA
Region IX, Subject: ``FW: SJV species responses,'' with attachments,
in which the attached tables have titles like ``Difference in Annual
PM2.5 mass and species between the 2024 baseline run and
the 30% PM reduction precursor run.''
\127\ In comparison to potential modeling of controlled
emissions, the NOX emissions for projected baseline years
2020 and 2024 are higher, ammonia would be less abundant relative to
NOX, and the responses to ammonia reductions would be
higher. Relying on baseline rather than controlled NOX
emissions levels was therefore conservative for purposes of the
ammonia precursor demonstration.
---------------------------------------------------------------------------
Finally, the EPA disagrees that a monitored 2022 design value being
``well above'' the modeled 2023 design value invalidates the modeling
for purposes of the precursor demonstration. As discussed in the EPA's
modeling TSD for the 2018 PM2.5 Plan,\128\ the State
determined that the model performance was excellent, and the EPA found
the results to be adequate for attainment demonstration modeling. The
modeling used a 2013 base year, i.e., the specific meteorological and
emissions conditions of 2013, not those of 2022 (nor of the 2018
monitored value used in scaling the modeling results from the 2018
PM2.5 Plan). Even when the modeling itself is valid, the
model-predicted design value can differ from a recent monitored design
value due to different meteorological conditions than in 2013 base
case, emissions variability, and atypical events that affect the
monitored value, but that are not necessarily reflected in the modeling
because they are inherently unpredictable.\129\ The greater uncertainty
in the precursor demonstration, which supports the EPA's conclusion in
this final action, is that the modeling seems to conservatively
overestimate the sensitivity of PM2.5 concentrations to
ammonia reductions compared to what would be expected based on ambient
measurements of ammonia and nitrate, as discussed in Response 3A.
---------------------------------------------------------------------------
\128\ EPA, ``Technical Support Document, EPA Evaluation of Air
Quality Modeling, San Joaquin Valley PM2.5 Plan for the
2006 PM2.5 NAAQS,'' February 2020.
\129\ The issue of how model predictions may not match monitor
observations despite a well-performing model, and how that does not
in itself invalidate the precursor demonstration is discussed in
more detail in the EPA's proposed disapproval of the 2018
PM2.5 Plan portion addressing the 1997 annual
PM2.5 NAAQS. 86 FR 67329, 67335 (November 26, 2021).
---------------------------------------------------------------------------
Comment 3.D: CCEJN's fourth concern with the precursor analysis is
that it believes that ``[t]he State improperly adopts a lax
contribution threshold of 0.25 [micro]g/m\3\.'' The commenter
acknowledges that the State's approach of using a 0.25 [micro]g/m\3\
threshold is consistent with the EPA's guidance but contends that the
guidance is arbitrary and capricious and that the EPA should reject it
in this rulemaking. To support their assertion, the commenter reasons
that
[t]he result of the state's approach is that an area, like the
San Joaquin Valley, that is failing to meet multiple successively
rigorous standards for the same measurement of the same pollutant,
may need to regulate a precursor only for purposes of the more
rigorous standard. This is a senseless result because the failure to
meet an already-outdated standard only highlights the necessity of
taking all feasible regulatory steps, including regulating relevant
precursors.
The commenter concludes that there is no advantage of two distinct
thresholds because the area will need to apply the lower threshold
eventually, and states that the ``EPA's failure to grapple with this
arbitrary result means that it has failed to provide a reasoned
explanation for its guidance, and the guidance--or at least its
application in this case--is arbitrary and capricious.'' For areas not
meeting both the 1997 and 2012 annual PM2.5 NAAQS, the
commenter proposes that the EPA should require states to apply the
threshold for the 2012 NAAQS for purposes of evaluating a precursor
contribution for both NAAQS.
Response 3.D: The EPA disagrees that the same contribution
threshold must be used regardless of the level of the NAAQS being
examined. The EPA believes that applying a threshold that is
proportional to the level of the NAAQS is appropriate and consistent
with the Act; i.e., 0.2 [micro]g/m\3\ is appropriate for the 2012
annual PM2.5 NAAQS of 12.0 [micro]g/m\3\, and 0.25 [micro]g/
m\3\ is appropriate for the 1997 annual PM2.5 NAAQS of 15.0
[micro]g/m\3\.
The contribution thresholds the EPA derived in the PM2.5
Precursor Demonstration Guidance represent a change in air quality that
is statistically indistinguishable from the inherent variability in the
measured atmospheric concentrations. A contribution threshold that is
proportional to, or scales with, the level of the NAAQS may also be
termed a ``relative'' approach, since the size of the threshold is
relative to the level of the NAAQS. The contribution thresholds in the
PM2.5
[[Page 86599]]
Precursor Demonstration Guidance were derived from a relative
variability estimate multiplied by the NAAQS level for the 2006 24-hour
PM2.5 NAAQS and 2012 annual PM2.5 NAAQS. Notably,
the PM2.5 Precursor Demonstration Guidance states: \130\
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\130\ PM2.5 Precursor Demonstration Guidance, p. 17,
fn. 20.
As described in the Technical Basis Document, the monitoring
site variability is first calculated as a percentage of the measured
PM2.5. Then the median percent variability from all sites
is multiplied by the level of the NAAQS to get the threshold
concentrations. Therefore, these thresholds represent a percentage
of the 2006 24-hour NAAQS (35 [mu]g/m\3\) and the 2012 annual NAAQS
(12 [mu]g/m\3\). Different thresholds may be applicable to other
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levels and/or forms of the NAAQS (either past or future).
The Technical Basis Document \131\ referred to in the guidance
explains that relative variability (concentration changes as a fraction
of total concentration) was found to be more stable than absolute
variability (concentration changes in [micro]g/m\3\), and notes that
this ``indicates that a central tendency value for the relative
variability in the DV [design value]. Therefore, a representative value
can be multiplied by the level of that NAAQS to obtain a value in
concentration units ([micro]g/m\3\ for PM2.5) that is
appropriately used to characterize variability.'' \132\ The Technical
Basis Document also explains that the ``relative variability was fairly
consistent across the range of design values, suggesting a commonality
in the relative variability across a wide range of geographic regions,
chemical regimes, and baseline air quality levels.'' \133\ Thus, a
concentration amount that is relative, or proportional, to the NAAQS
level is a better basis than a fixed concentration number for
determining the size of a concentration change that is within the
inherent variability of monitored concentrations. The superiority of
the relative variability approach that was the basis of the
PM2.5 Precursor Demonstration Guidance contribution
threshold of 0.2 [micro]g/m\3\ for the 2012 annual PM2.5
NAAQS makes it appropriate to scale that value according to the NAAQS
level to arrive at 0.25 [micro]g/m\3\ for the 1997 annual
PM2.5 NAAQS.
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\131\ EPA, ``Technical Basis for the EPA's Development of the
Significant Impact Thresholds for PM2.5 and Ozone,'' EPA-
454/R-18-001R-18-001, EPA OAQPS, April 2018, available at https://www.epa.gov/nsr/significant-impact-levels-ozone-and-fine-particles,
https://www.epa.gov/sites/default/files/2018-04/documents/ozone_pm2.5_sils_technical_document_final_4-17-18.pdf.
\132\ Technical Basis Document, p. 26.
\133\ Id. at 39.
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Moreover, the EPA does not agree that it is arbitrary or contrary
to the Act to apply a lower contribution threshold or to potentially
regulate a precursor only for a more stringent NAAQS--it is reasonable
to expect that achieving lower PM2.5 concentrations may
require regulation of additional sources of direct PM2.5
and/or PM2.5 precursors. This is true even if an area is
nonattainment for both the higher and lower NAAQS and the EPA will
ultimately be applying the lower contribution threshold for a
subsequent plan to attain the more stringent NAAQS. Indeed, the
PM2.5 SIP Requirements Rule at 40 CFR 51.1000 defines a
precursor demonstration to mean analyses showing that precursor
emissions do not contribute significantly to PM2.5 levels
that exceed the relevant PM2.5 standard'' [emphasis added]. Applying a
lower threshold for the 1997 annual PM2.5 NAAQS because the
area is in nonattainment for a more stringent NAAQS could presume that
the modeling and precursor demonstration in a future plan will show
responses to ammonia reductions above the lower threshold and that
ammonia will be determined to be significant, such that ammonia would
need to be controlled. The EPA does not believe it is appropriate to
prejudge the analyses for a potential future plan.
4. BACM/MSM Demonstration
Comment 4: Regarding the BACM demonstration, CCEJN notes that the
EPA's proposed approval does not address the CAA requirement for most
stringent measures (MSM), asserting that such analysis is required for
a 189(d) plan under 40 CFR 51.1010(c)(2)(i) and (c)(4), and 88 FR
45280, 45297, 45322. The commenter claims that it appears that the
State acknowledges that the MSM requirement applies in its submittal
and asserts that the EPA cannot approve the Plan until it reviews the
State's control measures under the MSM standard.
The commenter also states that ``[t]he state's control measures
meet neither the BACM nor MSM standards.'' They note that in previous
letters to the EPA (as summarized in a previous letter attachment
included as Exhibit B), Valley groups have identified numerous
weaknesses and presented ways the District could strengthen its
regulations. The commenter asserts that the EPA's technical support
document accompanying the proposed action addresses few of these
weaknesses, and advises that ``[t]o the extent EPA has not considered
whether the suggestions in the letter constitute BACM or MSM for
purposes of the 1997 annual standard, it should do so.'' Specifically,
the commenter notes that ``[o]ne particularly glaring shortfall in the
state's submission is its failure to contain any analysis of potential
control measures to minimize soil NOX emissions,'' and
suggests that the EPA must require the State to analyze the measures in
Exhibit A to CCEJN's comment letter (citing control measures described
on pages 5 and 6), including measures to reduce soil NOX
emissions from fertilized farmlands.
Response 4: We disagree with CCEJN's assertion that the EPA must
review the State's control measures analysis under the MSM standard. As
outlined in the PM2.5 SIP Requirements Rule, the CAA
requirement for MSM is tied to a specific trigger in the act--an
extension of the Serious area deadline under CAA section 188(e).\134\
The EPA addressed the relevance of MSM to a 189(d) plan as part of our
discussion of the control strategy for such plan in the technical
support document accompanying the final rule: \135\
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\134\ 81 FR 58010, 58094.
\135\ EPA, ``Response to Comments on the Fine Particulate Matter
National Ambient Air Quality Standards: State Implementation Plan
Requirements,'' July 29, 2016.
In addition to meeting the 5 percent emission reduction
requirement for PM2.5 or any PM2.5 plan
precursor, for any Serious nonattainment area that fails to attain
by the Serious area attainment date, the state is required to update
its control measures analysis in the section 189(d) plan. In the
event the area previously had received an extension of the Serious
area attainment date pursuant to section 188(e), the reevaluation of
control measures referenced in section 51.1010(c)(2) should include
a reevaluation of MSM. (For this reason, section 51.1010(c)(2)(i)
refers to the reevaluation of MSM ``as applicable.'') If, however,
the area did not previously request and receive an extension of the
Serious area attainment date under section 188(e), the MSM
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requirement does not apply.
Thus, we noted in the summary of the requirements for Serious
PM2.5 areas that fail to attain in our proposed action that
MSM is applicable only if the EPA granted an extension of the
attainment date under CAA section 188(e) for the area for the NAAQS at
issue.\136\
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\136\ 88 FR 45276, 45280, fn. 57.
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As discussed in our proposal, California's Serious area plan for
the 1997 PM2.5 NAAQS submitted in 2015 included a request
under CAA section 188(e) to extend the attainment date for the 1997
annual PM2.5 NAAQS by five years to December 31, 2020.\137\
However, after considering public comments, the EPA denied California's
request for an extension of the attainment date and subsequently
determined that the area failed to attain by the December 31, 2015
Serious area
[[Page 86600]]
attainment date, triggering the requirement for the 189(d) plan.
Consequently, because the San Joaquin Valley area did not receive an
extension of the Serious area attainment date under CAA section 188(e),
the MSM requirement does not apply for purposes of the 1997 annual
PM2.5 NAAQS.
---------------------------------------------------------------------------
\137\ Id. at 45277.
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Regarding the commenter's claim that the State appears to
acknowledge in its submission that MSM applies, we note that the
State's controls analysis in the 2018 PM2.5 Plan was
developed to address multiple PM2.5 NAAQS, including the
2006 PM2.5 NAAQS for which the State requested an attainment
date extension under CAA section 188(e), triggering the MSM requirement
for those NAAQS. Any assertion by the State in the SJV PM2.5
Plan that a particular measure meets the MSM standard may not
necessarily indicate that the State believes that the requirement
applies for the 1997 annual PM2.5 NAAQS. Regardless,
regarding CCEJN's comment that the State's control measures do not meet
the BACM or MSM standards, given that the MSM standard does not apply
to the 1997 annual PM2.5 NAAQS, as discussed earlier in this
response, we are responding only to the commenter's assertion regarding
BACM.
We also disagree with the commenter's assertion that the control
measures in the Plan do not meet the requirement for BACM for the 1997
annual PM2.5 NAAQS. As discussed in our proposed rule, in
our review of the State's and District's BACM demonstration, we
considered our evaluation of the State's and District's rules,
supporting information provided in the SJV PM2.5 Plan, and
our prior evaluations of the BACM and MSM demonstrations in the 2018
PM2.5 Plan for other PM2.5 NAAQS.\138\ These
prior evaluations include those to support our approval of the
demonstration for BACM (including BACT) for the 1997 24-hour
PM2.5 NAAQS,\139\ our approval of the demonstrations for
BACM and MSM for the 2006 24-hour PM2.5 NAAQS,\140\ and our
proposed disapproval of the demonstration for BACM for the 2012 annual
PM2.5 NAAQS.\141\ The EPA's prior actions for the 1997 24-
hour, 2006 24-hour, and 2012 annual PM2.5 NAAQS are relevant
to our evaluation for this final rulemaking because the State relied on
a common analysis for each of the PM2.5 standards. The EPA
conducted a thorough analysis of the State's BACM demonstration for
purposes of these prior actions, and updated the analysis for certain
source categories, as appropriate, for purposes of our proposed
approval of the BACM demonstration in the SJV PM2.5 Plan for
the 1997 annual PM2.5 NAAQS.
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\138\ Id. at 45305-45306.
\139\ 87 FR 4503 (January 28, 2022).
\140\ 85 FR 44192 (July 22, 2020).
\141\ 86 FR 74310 (December 29, 2021).
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Regarding the EPA's prior approval of the BACM demonstration in the
2018 PM2.5 Plan as meeting the CAA requirements for the 2006
24-hour PM2.5 NAAQS, we note that on September 17, 2020, a
group of five environmental, public health, and community groups
petitioned the Ninth Circuit Court of Appeals (``Ninth Circuit'') for
review of the EPA's final rulemaking approving the 2018
PM2.5 Plan's demonstration of BACM, BACT, and MSM for
emissions sources of direct PM2.5 and NOX for
purposes of the 2006 PM2.5 NAAQS.\142\ On April 13, 2022,
the Ninth Circuit denied the petitioners' challenge with respect to the
EPA's approval of the Plan's BACM/MSM demonstration, upholding such
approval for those NAAQS.
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\142\ See Medical Advocates for Healthy Air v. EPA, Case No. 20-
72780, Dkt. #58-1 (9th Cir., April 13, 2022). The five
environmental, public health, and community organizations, in order
of appearance in the petition, are Medical Advocates for Healthy
Air, National Parks Conservation Association, Association of
Irritated Residents, and Sierra Club.
---------------------------------------------------------------------------
Following approval of the State's BACM and MSM demonstrations for
the 2006 24-hour PM2.5 NAAQS, on December 29, 2021, the EPA
proposed to approve portions of the 2018 PM2.5 Plan as
meeting the Serious area requirements for the San Joaquin Valley for
the 2012 annual PM2.5 NAAQS, including the requirement that
the plan include BACM. However, after considering public comments, on
October 5, 2022, the EPA proposed to disapprove portions of the
District's BACM demonstration, including the evaluations of ammonia
emissions sources and building heating sources.\143\ We proposed to
disapprove the BACM demonstration for ammonia sources based in part on
our on proposed disapproval of the State's ammonia precursor analysis
for the 2012 annual PM2.5 NAAQS,\144\ as well as the State's
control measure analysis for ammonia.\145\ We proposed to disapprove
the BACM demonstration for building heating sources based on recent
control measure developments and the time horizon of the 2012 annual
PM2.5 NAAQS portion of the SJV PM2.5 Plan, which
raised questions about the feasibility of implementing additional
controls for such sources for BACM purposes in the San Joaquin
Valley.\146\ Notably, we did not re-propose action on any other
portions of the State's and District's BACM demonstration that we had
previously proposed to approve.
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\143\ 87 FR 60494.
\144\ Based on our proposed disapproval of the precursor
demonstration for the 2012 annual PM2.5 NAAQS, we
proposed to determine that ammonia remained a regulated precursor
for that NAAQS in the San Joaquin Valley.
\145\ 87 FR 60494, 60509.
\146\ Id. at 60511-60512.
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In response to the EPA's proposed disapproval of portions of the
BACM demonstration for the 2012 annual PM2.5 NAAQS, CARB and
the District developed and submitted additional information to support
the ammonia precursor demonstration and building heating BACM
demonstration for purposes of meeting the Serious area and CAA section
189(d) requirements for the 1997 annual PM2.5 NAAQS. Our
proposal and accompanying ``Technical Support Document, San Joaquin
Valley PM2.5 Plan Revision for the 1997 Annual
PM2.5 NAAQS,'' April 2023 (``EPA's 1997 Annual
PM2.5 TSD'') summarize the additional information provided
by the State and District and the EPA's evaluation. Based on our
review, we determined that the additional information provided by the
State and District addressed the deficiencies identified in the
proposed disapproval of the 2018 PM2.5 Plan for the 2012
annual PM2.5 NAAQS as they pertained to the 1997 annual
PM2.5 NAAQS. Thus, considering our prior approvals of the
State's and District's BACM analysis for the 1997 24-hour
PM2.5 NAAQS, BACM and MSM analysis for the 2006
PM2.5 NAAQS (which was upheld by the Ninth Circuit), and the
supplemental information provided to update the SJV PM2.5
Plan based on the latest information available, we proposed to approve
the BACM demonstration for the 1997 annual PM2.5 NAAQS.
Regarding the measures in Exhibit B to CCEJN's comment letter, the
EPA has reviewed and considered the recommendations for improvements to
the District's PM2.5 control strategy as outlined in the two
letters in Exhibit B sent by environmental groups to the EPA in 2021
\147\ and 2022.\148\ A detailed summary of our evaluation of the
feasibility of these measures, as well as numerous others, is provided
in Sections III and IV of the ``EPA Source Category and Control Measure
Assessment and Reasoned Justification
[[Page 86601]]
Technical Support Document'' (``Control Measure Assessment TSD'') \149\
accompanying our proposed action to promulgate a federal implementation
plan for contingency measures for the 1997 annual PM2.5
NAAQS, the 2006 24-hour PM2.5 NAAQS, and the 2012 annual
PM2.5 NAAQS.\150\ The EPA determined that the recommended
measures are either not technologically feasible or not economically
feasible within the two year timeframe for implementation as
contingency measures discussed in the EPA's draft guidance.\151\ Given
that by statute, contingency measures are additional requirements that
go beyond attainment planning requirements, and the shorter timeframe
of the attainment plan for the 1997 annual PM2.5 NAAQS
(i.e., by December 31, 2023), we similarly conclude that these measures
are not feasible for purposes of the BACM requirement for the SJV
PM2.5 Plan for the 1997 annual PM2.5 NAAQS.
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\147\ Letter dated October 22, 2021, from environmental
organizations to Michael S. Regan, Administrator, EPA, Subject:
``Meeting Request to Discuss PM-2.5 Crisis in the San Joaquin
Valley.''
\148\ Letter dated May 18, 2022, from environmental
organizations to Michael S. Regan, Administrator, Environmental
Protection Agency, Subject: ``Meeting Request to Discuss PM-2.5
Crisis in the San Joaquin Valley.''
\149\ EPA Region IX, ``EPA Source Category and Control Measure
Assessment and Reasoned Justification Technical Support Document,
Proposed Contingency Measures Federal Implementation Plan for the
Fine Particulate Matter Standards for San Joaquin Valley,
California,'' July 2023.
\150\ 88 FR 53431 (August 8, 2023).
\151\ EPA, Office of Air Quality Planning and Standards, Air
Quality Policy Division, ``DRAFT: Guidance on the Preparation of
State Implementation Plan Provisions that Address the Nonattainment
Area Contingency Measure Requirements for Ozone and Particulate
Matter'' (``Draft Guidance''), March 16, 2023, p. 41.
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Lastly, we disagree with CCEJN's assertion that the EPA must
require the State to analyze the control measures for soil
NOX emissions outlined in Exhibit A in order to approve the
BACM demonstration for the 1997 annual PM2.5 NAAQS. The EPA
previously addressed the issues of soil NOX emissions and of
analyzing potential controls for such emissions in the context of the
2018 PM2.5 Plan in the EPA's ``Response to Comments Document
for the EPA's Final Action on the San Joaquin Valley Serious Area Plan
for the 2006 PM2.5 NAAQS,'' June 2020 (``EPA's 2020 Response
to Comments'').\152\ More recently, the EPA also addressed the issue of
soil NOX emissions from the use of fertilizers and
pesticides in the context of our final rulemaking approving CARB's
submission of emissions inventories for VOC and NOX for the
2015 ozone NAAQS for areas in California (``2015 Ozone Inventory Final
Rule'').\153\
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\152\ EPA's 2020 Response to Comments, pp. 148-156, Comments and
responses 6.P-1 and 6.P-2.
\153\ 87 FR 59015 (September 29, 2022).
---------------------------------------------------------------------------
In both the EPA's 2020 Response to Comments and the 2015 Ozone
Inventory Final Rule, the EPA acknowledged the studies cited by
commenters finding that soil NOX emissions from fertilizer
and pesticide use contribute to atmospheric NOX levels in
California.\154\ Particularly, the EPA acknowledged the growing body of
research surrounding the identification and quantification of soil
NOX emissions from fertilizer application in agricultural
soils. However, in light of the uncertainties and disagreements among
the studies regarding the contribution of fertilized cropland soils to
NOX emissions in California, the EPA found that CARB's
emissions inventories met the applicable requirements of the CAA
notwithstanding the absence of soil NOX emissions from
fertilizer or pesticide use.\155\ Furthermore, for purposes of our
final action on the San Joaquin Valley Serious Area Plan for the 2006
PM2.5 NAAQS, we determined that there was not sufficient
information available to require a controls evaluation for soil
NOX emissions for purposes of the BACM analysis for those
NAAQS.\156\
---------------------------------------------------------------------------
\154\ Id. at 59018.
\155\ Id. at 59018-59020.
\156\ EPA's 2020 Response to Comments, p. 156.
---------------------------------------------------------------------------
Upon reviewing the studies cited by CCEJN in its comment letter, we
similarly find that the information provided is not sufficient to
compel a revision to the emissions inventories in the SJV
PM2.5 Plan for the 1997 annual PM2.5 NAAQS, given
the large uncertainties in the emissions estimates. As discussed in
Response 2.A, the magnitude of soil NOX emissions varies
based on temperature; agricultural practices, such as the timing and
amount of fertilizer application and irrigation; crop type; and other
factors. Additionally, soil NOX is not directly emitted and
involves numerous natural emissions sources and processes. Thus, soil
NOX emissions are inherently difficult to estimate and
model. Likewise, given that the production of NOX in the
soil is complex, it may also be challenging to estimate the effects of
potential controls. Due to the complexity of estimating soil
NOX emissions, the partially natural source of the
emissions, and the uncertainties in the effectiveness of potential
control measures, the EPA concludes that there is not sufficient
information available at this time to warrant an evaluation of
potential controls for soil NOX emissions in the San Joaquin
Valley for purposes of the BACM analysis for the 1997 annual
PM2.5 NAAQS. We encourage CARB and the District to continue
their ongoing efforts to resolve the uncertainties in soil
NOX emissions and examine any implications for air quality
modeling and planning.
5. Public Process
Comment 5: CCEJN asserts that the EPA must disapprove portions of
the attainment plan for the 1997 annual PM2.5 NAAQS because
the State did not provide public notice and the opportunity to comment
on portions of the Plan.
The commenter identifies two submissions made by CARB in March 2023
and June 2023 to provide additional information relevant to the
original SIP submissions comprising the Plan: the March 2023 Ammonia
Supplement and the March 2023 Building Heating Supplement, discussing
the ammonia precursor demonstration and the BACM requirement for
building electrification, and the Title VI Supplement, addressing
necessary assurances under CAA section 110(a)(2)(E). CCEJN notes that
CAA section 110(a)(2) requires ``[e]ach implementation plan submitted
by a State under this chapter shall be adopted by the State after
reasonable notice and public hearing.'' The commenter states that the
supplements are ``required contents of such plans'' and notes that the
EPA's supplemental proposal for the 2012 annual PM2.5 NAAQS
indicated the EPA's expectation that any Title VI necessary assurances
would go through state-level notice and comment along with the
remainder of the Plan.
Because CARB submitted these supplements directly to the EPA
without first going through additional public process and after CARB
had formally submitted the Plan, the commenter asserts that the EPA
cannot rely upon these supplements to approve the State's precursor
demonstration, BACM demonstration, or necessary assurances under CAA
section 110(a)(2)(E)(i).
Response 5: Generally, the EPA agrees with CCEJN that SIP
submissions must meet the reasonable notice and public hearing
requirements of CAA section 110(a)(2). This is a basic requirement for
SIP submissions that appears in section 110(a)(1), section 110(a)(2),
and section 110(l), as well as EPA regulations pertaining to the
completeness of SIP submissions in 40 CFR part 51, Appendix V. However,
the EPA does not agree that this requirement necessarily applies to all
information of any type that a state may provide to the EPA. This
includes such instances as when the state is providing additional
information to supplement a SIP submission that did previously meet
notice and public hearing process
[[Page 86602]]
requirements, particularly when the EPA has requested that the state
provide such additional information to clarify an ambiguity in the
original SIP submission or to aid the EPA in evaluating adverse
comments raising an issue related to the original SIP submission.\157\
The EPA considers it appropriate to rely on such supplemental
information, even if it is not in the form of a formal SIP submission
that underwent full notice and public hearing process, when it expands
on and confirms information presented in the state's original SIP
submission or addresses potential deficiencies in the pre-existing
data.\158\ In such situations, the EPA considers the relevant question
to be whether the state provided reasonable notice and public hearing
with respect to the issue as part of the original SIP submission. It
would be illogical to require a state to restart the entire SIP
development process and would delay the EPA's action on a SIP
submission, thereby potentially delaying needed emissions reductions,
were the Agency to interpret CAA section 110(a)(2) notice and public
hearing requirements to apply to any and all supplemental information
provided by state. Thus, the EPA disagrees with CCEJN's assertion that
it is inappropriate for the Agency to rely on the additional
information provided by CARB in the two supplements in its analysis of
the SJV PM2.5 Plan because it would violate the requirement
under section 110(a)(2) that plans submitted to the EPA for inclusion
in the SIP must go through ``reasonable notice and public hearing.''
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\157\ The EPA has previously explained that it may be
appropriate to rely on a supplemental letter from a state to resolve
ambiguities in a SIP submission. See 80 FR 33840, 33888 (June 12,
2015).
\158\ See 80 FR 33840, 33888 (``It is the EPA's practice to
neither require a state to resubmit a SIP submission nor repropose
action on the submission, so long as the clarification provided in
the interpretive letter is a logical outgrowth of the proposed SIP
provision.'').
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With respect to the 2023 Ammonia Supplement and the 2023 Building
Heating Supplement, the EPA believes the information contained therein
falls within the EPA's discretion to accept as a supplement, as it
expands upon and confirms information provided in the State's
previously submitted SIP submissions that did undergo the full notice
and public hearing process. CARB submitted the supplement to ``support
action on the attainment plan'' and the supplement was intended as
``clarifying information'' rather than a formal SIP revision.\159\
Also, CARB submitted this information in reaction to prior comments
related to the EPA's proposed action on the SIP submissions with
respect to the 2012 annual PM2.5 NAAQS, and in anticipation
of receiving those same comments in this action. In this respect, CARB
provided additional information that it anticipated the EPA would
request to help evaluate the issues raised in such comments.
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\159\ Letter dated March 29, 2023, from Steven S. Cliff,
Executive Officer, CARB, to Martha Guzman, Regional Administrator,
EPA Region 9, with enclosures.
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In the ammonia context, the 2018 PM2.5 Plan and 15
[micro]g/m\3\ SIP Revision present the fundamental elements of the
State's demonstration that ammonia does not contribute significantly to
exceedances of the 1997 annual PM2.5 NAAQS, including
research that supports its conclusion that ammonium nitrate
PM2.5 formation in the San Joaquin Valley is NOX-
limited rather than ammonia-limited; \160\ evidence that the area's
measures targeting VOC reductions are already reducing ammonia; \161\
and an analysis of how the District's control measures compare with
other state's rules and regulations.\162\ Upon initial review of the
State's submission, and in light of related comments received on
attainment plans for other PM2.5 NAAQS for the San Joaquin
Valley, the EPA requested clarifying information and additional
analysis to support the State's conclusions in the SJV PM2.5
Plan for the 1997 annual PM2.5 NAAQS.\163\ The information
and analysis the State provided in the March 2023 Ammonia Supplement
does not deviate from or fundamentally alter the analysis in the SJV
PM2.5 Plan; rather, it provides a wide array of potential
controls and analyses to support the fundamental conclusions in the
submitted SIP. The EPA believes that CARB provided reasonable notice
and public hearing on its position with respect to the ammonia
precursor issue in the initial SIP submission, and the additional
information in the March 2023 Ammonia Supplement merely expands upon
that position. Moreover, by taking into account the information that
CARB provided in that supplement during this rulemaking action, the EPA
itself has provided the commenters with the opportunity to address that
supplemental information now.
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\160\ 2018 PM2.5 Plan, Appendix G, pp. 9-10; CARB
December 2018 Staff Report, Appendix C, pp. 12-15; Attachment A to
CARB's May 9, 2019, submittal letter.
\161\ 2018 PM2.5 Plan, Appendix C, Section C-25.
\162\ Id.
\163\ 40 CFR 51.1010 authorizes the EPA to require supplemental
information on potential controls when the EPA deems it necessary to
evaluate the comprehensive precursor demonstration. The regulations
and EPA guidance do not instruct on what state-level processes this
supplemental information should go through in being submitted to the
EPA. See PM2.5 Precursor Demonstration Guidance, p. 31.
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Similarly, the building heating BACM demonstration in the 2018
PM2.5 Plan provides the foundations and analysis for CARB's
conclusions that the State is implementing BACM with respect to
building heating appliances. As discussed in Section II.A.4, in 2020,
the EPA approved this demonstration as meeting BACM for the 2006 24-
hour PM2.5 NAAQS.\164\ However, given comments concerning
this same issue on an EPA proposal related to the 2018 PM2.5
Plan with respect to 2012 annual PM2.5 NAAQS, the EPA
requested that the State support its conclusion with more up-to-date,
additional analysis.\165\ Like the supplemental information for the
ammonia precursor demonstration, the March 2023 Building Heating
Supplement merely provides additional support for the State's original
analysis and determination that it is implementing BACM for this source
category in the San Joaquin Valley area. The EPA believes that CARB
provided reasonable notice and public hearing on its position with
respect to the building heating and electrification issue during the
development of initial SIP submission, and the additional information
in the March 2023 Building Heating Supplement merely expands upon that
position.
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\164\ 85 FR 44192 (July 22, 2020).
\165\ 87 FR 60494 (October 5, 2022); Comment letter dated and
received January 28, 2022, from Brent Newell, Public Justice, et
al., to Rory Mays, EPA Region IX, including Exhibits 1 through 47.
We note, however, that there is no Exhibit 23; so, there are 46
exhibits in total. Email dated February 1, 2022, from Brent Newell,
Public Justice, to Rory Mays, EPA Region IX. The 13 environmental,
public health, and community organizations are Public Justice,
Central Valley Environmental Justice Network, Association of
Irritated Residents, Central Valley Air Quality Coalition,
Leadership Counsel for Justice and Accountability, Valley
Improvement Projects, The LEAP Institute, Little Manila Rising,
Center for Race, Poverty, and the Environment, Central California
Asthma Collaborative, Animal Legal Defense Fund, National Parks
Conservation Association, and Food and Water Watch.
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Thus, the EPA believes the State provided reasonable notice and
opportunity for public engagement with respect to its conclusions in
the ammonia precursor demonstration and building heating BACM elements
of the SIP and satisfied the reasonable notice and public hearing
requirements of the CAA.\166\
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\166\ The EPA notes that a review of the State's records
submitted with the SIP indicates that the public did identify these
two elements prior to and during the public hearing held on the
State's approval of the SIP in 2021.
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With respect to the Title VI Supplement, the EPA acknowledges that
[[Page 86603]]
it provides additional information related to an issue that the State
did not expressly address during the development of the SJV
PM2.5 Plan, i.e., the State did not previously engage in
public process specifically with respect to CAA section 110(a)(2)(E)
necessary assurances that implementation of the Plan would not be
prohibited by Title VI. However, in this instance, the issue of
necessary assurances arose in adverse comments on a related EPA
proposed action on the same 2018 PM2.5 Plan with respect to
the 2012 PM2.5 NAAQS.\167\ In order to address the concerns
raised by the commenter, the EPA sought additional information from the
State to supplement the SJV PM2.5 Plan by providing
necessary assurances and CARB provided that information in the Title VI
Supplement to do so.
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\167\ 86 FR 74310 (December 29, 2021). Some of the environmental
and community organizations that contributed to the adverse comments
related to necessary assurances on the EPA's proposed SIP action for
the 2012 annual PM2.5 NAAQS are among the organizations
that provided the adverse comments on the EPA's proposal for the
1997 annual PM2.5 NAAQS discussed herein.
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In light of prior comments, and the responsiveness of the Title VI
Supplement to the prior comments, the EPA considers it appropriate to
rely on the additional information provided by CARB in this way. Going
forward, as part of developing new SIP submissions, the EPA requests
that CARB and the District include consideration of issues related to
compliance with Title VI as part of that process, in order to ensure
public awareness and engagement. The public notice and comment process
required for development of SIP submissions provides an opportunity for
an air agency to share its position on necessary assurances publicly,
and to develop the record supporting their analysis of CAA section
110(a)(2)(E)(i) as it pertains to a particular SIP submission. Through
this process, the EPA expects states to develop adequate necessary
assurances so that they can be reviewed during the air agency-level
public comment process and subsequently by the EPA.\168\
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\168\ The EPA notes that the content of the Title VI Supplement
is substantially similar to recent submissions of necessary
assurances from the State on the attainment plan for the 2015 ozone
NAAQS (see ``Staff Report, CARB Review of the San Joaquin Valley
2022 Plan for the 70 ppb 8-Hour Ozone Standard'' (release date:
December 16, 2022), pp. 21-23). The plan for the 2015 ozone NAAQS,
which was submitted after the EPA's supplemental proposal on the
plan for the 2012 annual PM2.5 NAAQS, was made available
for public review during the State's public comment processes (see
CARB's ``Notice of Public Meeting to Consider Proposed San Joaquin
Valley 70 parts per billion Ozone State Implementation Plan,'' dated
December 16, 2022).
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B. Comments From Central Valley Air Quality Coalition (CVAQ)
Comment 6: CVAQ's comments cover many of the same issues as the
comments from CCEJN. In summary, they assert that the State's plan
``improperly relies upon faulty emission inventories and modeling data,
fails to regulate key PM2.5 precursors like ammonia and soil
NOX, does not analyze the most stringent measures needed for
attainment, and does nothing to prove State compliance with Title VI of
the Civil Rights [Act] (Title VI).'' The commenter also notes that the
two CARB-submitted supplements did not go through the State's public
process, and that the EPA had an obligation to issue a federal
implementation plan in January 2021 and has failed to do so.
Response 6: The EPA has addressed CVAQ's concerns about the
emissions inventory and modeling data in Response 2.B; ammonia in
Responses 3.A through 3.D; soil NOX in Responses 2.A and 4;
MSM in Response 4; Title VI in Responses 1.A and 1.B, Response 5, and
in Response 7 that follows; and the State's public process in Response
5 of this document.
Regarding the EPA's federal implementation plan (FIP) obligation,
we do not dispute that the EPA has had an obligation to implement a FIP
for the San Joaquin Valley for the 1997 annual PM2.5 NAAQS
due to a prior finding of failure to submit the required attainment
plan. As we explained in the proposed rule, as a result of the EPA's
December 6, 2018 determination effective January 7, 2019, that
California had failed to submit the required attainment plan for the
1997 annual PM2.5 NAAQS, among other required SIP
submissions for the San Joaquin Valley, the EPA became subject to a
statutory deadline to promulgate a FIP for this purpose no later than
two years after the effective date of that determination--i.e., by
January 7, 2021.\169\ However, as a result of this final rulemaking
approving all but the contingency measure requirement of the submitted
Serious area and section 189(d) plan for the 1997 annual
PM2.5 NAAQS, the only outstanding deficiency for these NAAQS
relates to contingency measures. We note that CARB has submitted three
SIP submissions to address the CAA contingency measure requirements for
the 1997 annual PM2.5 NAAQS (as well as other
PM2.5 NAAQS) in the San Joaquin Valley, including (1) the
``PM2.5 Contingency Measure State Implementation Plan
Revision,'' submitted to the EPA on June 8, 2023; \170\ (2) amendments
to District Rule 8051 (``Open Areas''), submitted to the EPA on October
16, 2023; \171\ and (3) the state-wide ``California Smog Check
Contingency Measure for the State Implementation Plan,'' submitted to
the EPA on November 13, 2023.\172\ The EPA will act on the contingency
measure SIP revisions, and/or promulgate a FIP for the contingency
measure requirement for the 1997 annual PM2.5 NAAQS and
other NAAQS, in a separate rulemaking.
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\169\ 88 FR 45276, 45278.
\170\ Letter dated June 7, 2023, from Steven S. Cliff, Executive
Officer, CARB, to Martha Guzman, Regional Administrator, EPA Region
IX.
\171\ Letter dated October 13, 2023, from Steven S. Cliff,
Executive Officer, CARB, to Martha Guzman, Regional Administrator,
EPA Region IX.
\172\ Letter dated November 13, 2023, from Steven S. Cliff,
Executive Officer, CARB, to Martha Guzman, Regional Administrator,
EPA Region IX.
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C. Comments From a Private Individual
Comment 7: The private citizen commenter believes that the State's
plan contains ``aspirational and misleading `assurances' of compliance
with the Civil Rights Act'' and that the ``EPA has missed an
opportunity to live up to the commitments of the Biden administration
and EPA Administrator Regan to prioritize environmental justice and
civil rights.''
In addition, the commenter notes the length of time that has passed
since the EPA committed to put out guidance on what would constitute
``necessary assurances'' under the Act and its failure to do so prior
to accepting the necessary assurances demonstration in the SJV
PM2.5 Plan for the 1997 annual PM2.5 NAAQS. The
commenter recommends that a simple interim guidance could include: (1)
``some sort of equity or environmental justice assessment,'' and (2)
``consideration of alternative measures to lessen or eliminate any
potentially discriminatory burdens revealed by that assessment.''
The commenter provides a short summary of the interaction between
CAA section 110(a)(2)(E) and Title VI at the EPA, including identifying
a SIP rulemaking in 1997 where the connection between section
110(a)(2)(E) and Title VI was raised and a 2012 rulemaking pertaining
to the San Joaquin Valley on which the EPA received comments about the
same issue.
The commenter generally recommends that the EPA exercise its
discretion in determining what constitutes necessary assurances to
require more from the State in favor of a more rigorous posture as to
what constitutes necessary assurances. In doing so, the commenter
disputes the
[[Page 86604]]
EPA's distinction in its proposal between necessary assurances under
CAA section 110(a)(2)(E) and a formal finding of compliance with Title
VI.
Next, the commenter outlines the contents of CARB's Title VI
supplement. In particular, the commenter alleges that CARB's Civil
Rights and Discrimination Process does not have processes or procedures
for handling a complaint originating from outside of CARB, that the
policy has been rarely used, and was adopted prior to complaints filed
at the EPA against CARB for procedural deficiencies in the State's
policy. Additionally, the commenter believes that neither the EPA nor
CARB has demonstrated that the State's policy will be implemented in a
systemic manner to avoid disproportionate effects.
The commenter asserts that the EPA's approval of the necessary
assurances conflates the concrete statutory requirements of Title VI
with policy-based programs and policies of environmental justice. The
commenter believes that relying on the policy-based environmental
justice initiatives does not rise to the level of the systematic and
defined methods of Title VI compliant laws.
The commenter then describes many of the environmental justice
resources available to CARB and the EPA in developing and determining
the adequacy of necessary assurances. The commenter acknowledges that
the EPA identified many of these resources in its proposal but believes
the necessary assurances discussion should demonstrate that these
resources were considered and used in determining whether there is a
disproportionate effect in a particular SIP-based action.
Ultimately, based on 2013 EPA guidance on compliance with CAA
section 110(a)(2)(E) and the terms of conditions under Title VI for
CARB receiving funding from the EPA, the commenter does not believe
that CARB submitted a sufficient demonstration that the required Title
VI compliance programs exist under CARB's purview. In their conclusion,
the commenter notes that the EPA could conditionally approve the Plan,
accompanied by an enforceable condition requiring CARB and the District
to bring their programs into demonstrated compliance with Title VI.
Response 7: To the extent the comment letter is providing input to
the EPA on content for a forthcoming guidance document for CAA section
110(a)(2)(E)(i) with respect to Title VI, such considerations are
outside the scope of this action.
As we noted in our proposal, the EPA has discretion with regard to
what may constitute necessary assurances under CAA section
110(a)(2)(E)(i). For this action, we believe the State has provided
adequate necessary assurances to support approval, under these specific
facts and circumstances. The EPA notes that what constitutes necessary
assurances for purposes of Title VI for a given SIP submission depends
upon the facts and circumstances of the Plan, and the Agency may
require more or different information as needed in other SIP actions.
This finding does not limit the Agency to review for different factors
in the future.
Importantly, as explained in the proposal action, the EPA's
evaluation of necessary assurances pertains to CAA section
110(a)(2)(E)(i) compliance with respect to a specific SIP submission,
and not to Title VI compliance more broadly.\173\ Formal findings of
compliance with Title VI follow procedures outlined in the CFR after
administrative complaints are filed with the EPA alleging
discrimination prohibited by Title VI and the other civil rights
laws,\174\ or if the EPA initiates an affirmative compliance
review.\175\ Section 110(a)(2)(E)(i), in contrast, requires a state to
provide necessary assurances that the state's implementation of the SIP
submission at issue is not prohibited by federal law, including Title
VI. As an additional point of clarification, this necessary assurances
analysis concerning Title VI is distinct from considerations of
environmental justice more broadly. Title VI involves specific
considerations of federal law as it pertains to individuals on the
basis of race, color, or national origin. The language at issue in CAA
section 110(a)(2)(E)(i) is specific to implementation of the SIP
submissions and prohibitions under Title VI.
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\173\ 88 FR 45276, 45320.
\174\ 40 CFR 7.120.
\175\ 40 CFR 7.115.
---------------------------------------------------------------------------
The EPA separately reviewed information related to environmental
justice considerations and those considerations are addressed in
Section IV of this document. The EPA reiterates that in our proposed
approval of the Plan, the EPA completed a Demographic Index analysis of
the area subject to the Plan, identifying environmental burdens and
susceptible populations in disadvantaged communities in the San Joaquin
Valley nonattainment area. As explained in more detail in Section
II.A.1 of this document, we believe the State has provided the
necessary assurances, including information that through its initial
implementation that the State has meaningfully considered input from
the public through public outreach that is beyond the minimum legal
requirements for public comment during SIP development, and that the
Plan submission complies with CAA section 110(a)(2)(E)(i).
With respect to the ``EPA's processing prior (to this 2023 action
but subsequent to the 2016 policy) complaints against CARB and in which
it had noted several procedural deficiencies,'' the EPA is not aware of
any complaints filed against CARB within that time period regarding
CARB's Civil Rights and Discrimination Complaint Process, and no
complaint was specifically cited to by the commenter.\176\ The EPA
notes that it publishes all external civil rights complaints and
compliance reviews online.\177\
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\176\ On June 6, 2016, the EPA resolved a civil rights complaint
filed against CARB and the Bay Area Air Quality Management District.
After an investigation by the EPA's Office of Civil Rights (OCR),
the Agency found ``insufficient evidence of current non-compliance
with Title VI or EPA' s Title VI regulation'' and closed the
complaint. In the letter closing the complaint, the EPA notes that
``OCR has provided technical assistance to CARB to improve the
elements of its non-discrimination program,'' including improvements
to CARB's Civil Rights and Discrimination Complaint Process. The
closure letter specifically found ``CARB has also adopted a
grievance procedure that is contained in the Civil Rights Policy and
Discrimination Complaint Process that provides complainants a prompt
and impartial investigation of and response to complaints filed with
CARB alleging discrimination in CARB's programs or activities
prohibited by the federal non-discrimination statutes.'' The EPA
does not believe this complaint resolution and the conclusions
therein conflicts with the determinations in this final action.
https://www.epa.gov/sites/default/files/2016-06/documents/2r-00-r9_carb_resolution_letter.pdf.
\177\ EPA, External Civil Rights Docket, https://www.epa.gov/external-civil-rights/external-civil-rights-docket-2014-present.
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III. Motor Vehicle Emissions Budgets and Transportation Conformity
The EPA previously determined that the 2020 and 2023 motor vehicle
emissions budgets in the 15 [micro]g/m\3\ SIP Revision were adequate
for use in transportation conformity findings. 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.\178\ The EPA announced the
availability of the budgets and notified the public of the adequacy
finding via a Federal Register
[[Page 86605]]
notice on February 10, 2022.\179\ 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.
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\178\ Letter dated February 1, 2022, from Matthew Lakin, Acting
Director, Air and Radiation Division, EPA Region IX, to Richard
Corey, Executive Officer, CARB.
\179\ 87 FR 7834 (February 10, 2022).
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The EPA proposed approval of these same budgets, shown in Table 1
of this document, on July 14, 2023.180 181 The Plan
establishes separate direct PM2.5 and NOX subarea
budgets, based on EMFAC2014, for each county, and partial county (for
Kern County), in the San Joaquin Valley.\182\ The EPA discussed the
State's evaluation of the significance/insignificance factors for
ammonia, SO2, and VOC, and re-entrained road dust emissions
in the proposed rule.\183\ In this action, the EPA is finalizing
approval of 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. Therefore, consistent with the
transportation conformity regulation,\184\ motor vehicle emissions
budgets are not required for transportation-related emissions of
ammonia, SO2, and VOC for purposes of the 1997 annual
PM2.5 NAAQS in the San Joaquin Valley. In addition, since
neither the State nor the EPA has made a finding that re-entrained road
dust emissions are significant, under 40 CFR 93.103(b)(3) and
93.122(f), re-entrained road dust emissions are not required to be
included in the budgets for 1997 annual PM2.5 NAAQS in the
San Joaquin Valley.
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\180\ 88 FR 45276, 45322.
\181\ The EPA did not receive any comments related to our
proposed approval of the motor vehicle emissions budgets during the
30-day comment period.
\182\ 40 CFR 93.124(c) and (d).
\183\ 88 FR 45276, 45316-45317.
\184\ 40 CFR 93.102(b)(2)(v).
Table 1--Motor Vehicle Emissions Budgets for the San Joaquin Valley for the 1997 Annual PM2.5 NAAQS
[Annual average, tons per day]
----------------------------------------------------------------------------------------------------------------
2020 (RFP year) 2023 (attainment year)
County ---------------------------------------------------------------------------
PM2.5 NOX PM2.5 NOX
----------------------------------------------------------------------------------------------------------------
Fresno.............................. 0.9 25.3 0.8 15.1
Kern................................ 0.8 23.3 0.7 13.3
Kings............................... 0.2 4.8 0.2 2.8
Madera.............................. 0.2 4.2 0.2 2.5
Merced.............................. 0.3 8.9 0.3 5.3
San Joaquin......................... 0.6 11.9 0.6 7.6
Stanislaus.......................... 0.4 9.6 0.4 6.1
Tulare.............................. 0.4 8.5 0.4 5.2
----------------------------------------------------------------------------------------------------------------
Source: 15 [micro]g/m\3\ SIP Revision, Appendix D, Table 18. Budgets are rounded up to the nearest tenth of a
ton.
For the reasons discussed in Sections IV.D and IV.E of the proposed
rule, the EPA is approving the attainment, RFP, and 5 percent
demonstrations, respectively, in the SJV PM2.5 Plan. The
2020 RFP and 2023 attainment year budgets 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 is finalizing approval of the 2020 and 2023
budgets listed in Table 1 of this document.
The Plan also included budgets for direct PM2.5 and
NOX emissions for 2017 (RFP milestone year) and 2026 (post-
attainment quantitative milestone year). We are not approving the 2017
budgets \185\ or the post-attainment year 2026 budgets at this time.
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. However, 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.
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\185\ We are not approving the 2017 budgets because such budgets
would not be used in any future transportation conformity
determination because the Plan includes budgets for 2020.
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Conformity Trading Mechanism
Also on July 14, 2023, the EPA proposed to approve a 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 as allowed for under 40 CFR
93.124(b).186 187 As described in the proposed rule, the EPA
reviewed the trading mechanism and found it is appropriate for
transportation conformity purposes in the San Joaquin Valley for the
1997 annual PM2.5 NAAQS.\188\ The methodology for estimating
the trading ratio for conformity purposes is essentially an update
(based on newer modeling) to the State's approach, approved in the
previous plan, to model the effect of areawide direct PM2.5
and NOX emissions reductions on ambient PM2.5,
and to express the ratio of these modeled sensitivities as an inter-
pollutant trading ratio.
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\186\ 88 FR 45276, 45322.
\187\ The EPA did not receive any comments related to our
proposed approval of the trading mechanism for transportation
conformity during the 30-day comment period.
\188\ 88 FR 45276, 45318-45319.
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In a previous 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.\189\ Here, we similarly find that the
State's approach is reasonable and are approving the 6.5 to 1
NOX for PM2.5 trading mechanism as enforceable
components of the
[[Page 86606]]
transportation conformity program for the San Joaquin Valley for the
1997 annual PM2.5 NAAQS. This trading ratio replaces 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.\190\
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\189\ See 86 FR 49100, 49128 (September 1, 2021) (proposed rule)
and 86 FR 67343, 67346 (November 26, 2021) (final rule).
\190\ 76 FR 69896.
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IV. Environmental Justice Considerations
As described in detail in our proposal, the EPA reviewed
environmental and demographic data for the San Joaquin Valley using the
EPA's environmental justice (EJ) screening and mapping tool
(``EJSCREEN''),191 192 and compared the data to the
corresponding data for the United States as a whole. The results of the
analysis are provided for informational and transparency purposes.
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\191\ 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. These indicators are included in EJSCREEN reports
that are available in the rulemaking docket for this action.
\192\ EPA Region IX, ``EJSCREEN Analysis for the Eight Counties
of the San Joaquin Valley Nonattainment Area,'' August 2022.
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This final action approves the State's plan for attaining the 1997
annual PM2.5 NAAQS. Information on the 1997 annual
PM2.5 NAAQS and its relationship to 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.
V. Final Action
For the reasons discussed in this final rule, the proposed rule,
and the related technical support documents, under CAA section
110(k)(3), the EPA is approving the portions of the SJV
PM2.5 Plan as meeting CAA requirements for implementation of
the 1997 annual PM2.5 NAAQS as follows:
(1) We are finding that the 2013 base year emissions inventories
continue to satisfy the requirements of CAA section 172(c)(3) and 40
CFR 51.1008 for purposes of both the Serious area and the CAA section
189(d) attainment plans, and to find that the forecasted inventories
for the years 2017, 2018, 2019, 2020, 2023, and 2026 provide an
adequate basis for the BACM, RFP, five percent, and modeled attainment
demonstration analyses;
(2) We are approving the following elements as meeting the Serious
nonattainment area planning requirements:
(a) the BACM/BACT demonstration as meeting the requirements of CAA
section 189(b)(1)(B) and 40 CFR 51.1010(a);
(b) the demonstration (including air quality modeling) that the
Plan provides for attainment as expeditiously as practicable as meeting
the requirements of CAA sections 179(d) and 189(b) and 40 CFR
51.1011(b);
(c) the RFP demonstration as meeting the requirements of CAA
sections 172(c)(2) and 171(1) and 40 CFR 51.1012; and
(d) the quantitative milestone demonstration as meeting the
requirements of CAA section 189(c) and 40 CFR 51.1013;
(3) We are approving the following elements as meeting the CAA
section 189(d) planning requirements:
(a) the BACM/BACT demonstration as meeting the requirements of CAA
sections 189(a)(1)(C) \193\ and 189(b)(1)(B) and 40 CFR 51.1010(c);
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\193\ As discussed in Section III.B of the proposal, a section
189(d) plan must address any outstanding Moderate or Serious area
requirements that have not previously been approved. Because we have
not previously approved a subpart 4 RACM demonstration for the San
Joaquin Valley nonattainment area, we also proposed to approve the
BACM/BACT demonstration in the SJV PM2.5 Plan as meeting
the subpart 4 RACM/RACT requirement for the area (88 FR 45276,
45322).
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(b) the demonstration that the Plan will, at a minimum, achieve an
annual five percent reduction in emissions of NOX as meeting
the requirements of CAA section 189(d) and 40 CFR 51.1010(c);
(c) the demonstration (including air quality modeling) that the
Plan provides for attainment as expeditiously as practicable as meeting
the requirements of CAA sections 179(d) and 189(d) and 40 CFR
51.1011(b);
(d) the RFP demonstration as meeting the requirements of CAA
sections 172(c)(2) and 171(1) and 40 CFR 51.1012; and
(e) the quantitative milestone demonstration as meeting the
requirements of CAA section 189(c) and 40 CFR 51.1013;
(4) We are approving the motor vehicle emissions budgets for 2020
and 2023 as shown in Table 1 of this final rulemaking because they are
derived from approvable RFP and attainment demonstrations and meet the
requirements of CAA section 176(c) and 40 CFR part 93, subpart A; and
(5) We are approving the trading mechanism provided for use in
transportation conformity analyses for the 1997 annual PM2.5
NAAQS, in accordance with 40 CFR 93.124(b).
As discussed in Section I.B of the proposal, on November 26, 2021,
the EPA partially approved and partially disapproved portions of the
2018 PM2.5 Plan that addressed attainment of the 1997 annual
PM2.5 NAAQS in the San Joaquin Valley nonattainment area.
The elements that the EPA disapproved include the attainment
demonstration, comprehensive precursor demonstration, five percent
annual emissions reductions demonstration, BACM demonstration, RFP
demonstration, quantitative milestones, motor vehicle emissions
budgets, and contingency measures. This disapproval was effective on
December 27, 2021. In a separate final partial approval and partial
disapproval action, also effective December 27, 2021, the EPA
disapproved the contingency measure element of the 2018
PM2.5 Plan as it relates to the requirements for the Serious
area plan 2006 24-hour PM2.5 NAAQS and the Moderate area
plan for the 2012 annual PM2.5 NAAQS.\194\
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\194\ 86 FR 67343.
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In our November 26, 2021 final disapprovals, we noted that offset
and highway sanctions under CAA sections 179(b)(2) and 179(b)(1),
respectively, would not apply if California submits, and the EPA
approves, a SIP submission that corrects all of the deficiencies
identified in our final actions prior to the imposition of
sanctions.\195\ Through this final approval action, we find that
California has corrected the deficiencies associated with the Serious
area and CAA section 189(d) SIP elements for the 1997 annual
PM2.5 NAAQS for the San Joaquin Valley (except for the
contingency measures element). Thus, upon the effective date of this
final rule, all sanctions and any sanctions clocks associated with the
Serious area and CAA section 189(d) SIP elements for the 1997 annual
PM2.5 NAAQS for the San Joaquin Valley (except the
contingency measures element) will be permanently terminated.
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\195\ 86 FR 67329.
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This final action does not address the prior disapprovals of the
contingency measure elements for the 1997 annual
[[Page 86607]]
PM2.5 NAAQS, the 2006 24-hour PM2.5 NAAQS, and
the 2012 annual PM2.5 NAAQS. Therefore, all sanctions and
any sanctions clocks associated with the disapprovals of the
contingency measure elements for those standards will continue to apply
in the San Joaquin Valley as outlined in the November 26, 2021 final
disapprovals unless or until the EPA approves a SIP submission or
submissions meeting the outstanding contingency measure requirements
for these NAAQS. As discussed in Response 6, CARB has submitted three
SIP submissions to address the CAA contingency measure requirements for
the 1997 annual PM2.5 NAAQS, the 2006 24-hour
PM2.5 NAAQS, and the 2012 annual PM2.5 NAAQS in
the San Joaquin Valley. The EPA will act on these submissions and
determine the effects on the sanctions, if any, in accordance with 40
CFR 52.31 through one or more separate rulemaking actions.
VI. Statutory and Executive Order Reviews
Under the Clean Air Act, the Administrator is required to approve a
SIP submission that complies with the provisions of the Act and
applicable federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a).
Thus, in reviewing SIP submissions, the EPA's role is to review state
choices, and approve those choices if they meet the minimum criteria of
the Act. Accordingly, this final action merely approves State law as
meeting federal requirements and does not impose additional
requirements beyond those imposed by State law. For that reason, this
action:
Is not a significant regulatory action subject to review
by the Office of Management and Budget under Executive Orders 12866 (58
FR 51735, October 4, 1993) and 14094 (88 FR 21879, April 11, 2023);
Does not impose an information collection burden under the
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
Is certified as not having a significant economic impact
on a substantial number of small entities under the Regulatory
Flexibility Act (5 U.S.C. 601 et seq.);
Does not contain any unfunded mandate or significantly or
uniquely affect small governments, as described in the Unfunded
Mandates Reform Act of 1995 (Pub. L. 104-4);
Does not have federalism implications as specified in
Executive Order 13132 (64 FR 43255, August 10, 1999);
Is not subject to Executive Order 13045 (62 FR 19885,
April 23, 1997) because it approves a State program;
Is not a significant regulatory action subject to
Executive Order 13211 (66 FR 28355, May 22, 2001); and
Is not subject to requirements of Section 12(d) of the
National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272
note) because application of those requirements would be inconsistent
with the Clean Air Act.
In addition, the SIP is not approved to apply on any Indian
reservation land or in any other area where the EPA or an Indian tribe
has demonstrated that a tribe has jurisdiction. In those areas of
Indian country, the rule does not have tribal implications and will not
impose substantial direct costs on tribal governments or preempt tribal
law as specified by Executive Order 13175 (65 FR 67249, November 9,
2000).
Executive Order 12898 (Federal Actions To Address Environmental
Justice in Minority Populations and Low-Income Populations, 59 FR 7629,
Feb. 16, 1994) directs federal agencies to identify and address
``disproportionately high and adverse human health or environmental
effects'' of their actions on minority populations and low-income
populations to the greatest extent practicable and permitted by law.
The EPA defines environmental justice (EJ) as ``the fair treatment and
meaningful involvement of all people regardless of race, color,
national origin, or income with respect to the development,
implementation, and enforcement of environmental laws, regulations, and
policies.'' The EPA further defines the term fair treatment to mean
that ``no group of people should bear a disproportionate burden of
environmental harms and risks, including those resulting from the
negative environmental consequences of industrial, governmental, and
commercial operations or programs and policies.''
The State did not evaluate environmental justice considerations as
part of its SIP submittal; the CAA and applicable implementing
regulations neither prohibit nor require such an evaluation. The EPA's
evaluation of environmental justice is described in the section of this
document titled, ``Environmental Justice Considerations.'' The analysis
was done for the purpose of providing additional context and
information about this rulemaking to the public, not as a basis of the
action. Due to the nature of the action being taken here, this action
is expected to have a neutral to positive impact on the air quality of
the affected area. In addition, there is no information in the record
upon which this decision is based that is inconsistent with the stated
goal of E.O. 12898 of achieving environmental justice for people of
color, low-income populations, and Indigenous peoples.
This action is subject to the Congressional Review Act, and the EPA
will submit a rule report to each House of the Congress and to the
Comptroller General of the United States. This action is not a ``major
rule'' as defined by 5 U.S.C. 804(2).
Under section 307(b)(1) of the Clean Air Act, petitions for
judicial review of this action must be filed in the United States Court
of Appeals for the appropriate circuit by February 12, 2024. Filing a
petition for reconsideration by the Administrator of this final rule
does not affect the finality of this action for the purposes of
judicial review nor does it extend the time within which a petition for
judicial review may be filed, and shall not postpone the effectiveness
of such rule or action. This action may not be challenged later in
proceedings to enforce its requirements. (See section 307(b)(2).)
List of Subjects in 40 CFR Part 52
Environmental protection, Air pollution control, Incorporation by
reference, Particulate matter, Reporting and recordkeeping
requirements.
Authority: 42 U.S.C. 7401 et seq.
Dated: December 5, 2023.
Martha Guzman Aceves,
Regional Administrator, Region IX.
Part 52, chapter I, title 40 of the Code of Federal Regulations is
amended as follows:
PART 52--APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS
0
1. The authority citation for Part 52 continues to read as follows:
Authority: 42 U.S.C. 7401 et seq.
Subpart F--California
0
2. Section 52.220 is amended by adding paragraphs (c)(537)(ii)(A)(9)
and (10) and (c)(537)(ii)(B)(7), (8), and (9) to read as follows:
Sec. 52.220 Identification of plan--in part.
* * * * *
(c) * * *
(537) * * *
(ii) * * *
(A) * * *
(9) CARB Resolution No. 21-21, September 23, 2021, submitted as a
revision to the 2018 PM2.5 Plan on
[[Page 86608]]
November 8, 2021, by the Governor's designee.
(10) ``Staff Report, Proposed SIP Revision for the 15 [mu]g/m\3\
Annual PM2.5 Standard for the San Joaquin Valley,'' August
13, 2021, submitted as a revision to the 2018 PM2.5 Plan on
November 8, 2021, by the Governor's designee.
(B) * * *
(7) 2018 Plan for the 1997, 2006, and 2012 PM2.5
Standards (``2018 PM2.5 Plan''), adopted November 15, 2018
(portions pertaining to the 1997 annual PM2.5 NAAQS only,
and excluding Chapter 4 (``Attainment Strategy for PM2.5''),
Chapter 5 (``Demonstration of Federal Requirements for 1997
PM2.5 Standards''), Chapter 6 (``Demonstration of Federal
Requirements for 2006 PM2.5 Standards''), Chapter 7
(``Demonstration of Federal Requirements for 2012 PM2.5
Standards''), Appendix D (``Mobile Source Control Measure Analyses''),
Appendix H (``RFP, Quantitative Milestones, and Contingency''), and
Appendix K (``Modeling Attainment Demonstration'')).
(8) ``Attainment Plan Revision for the 1997 Annual PM2.5
Standard,'' August 19, 2021, excluding Appendix H, section H.3
(``Contingency Measures''), submitted as a revision to the 2018
PM2.5 Plan on November 8, 2021, by the Governor's designee.
(9) SJVUAPCD Governing Board Resolution No. 21-08-13, August 19,
2021, submitted as a revision to the 2018 PM2.5 Plan on
November 8, 2021, by the Governor's designee.
* * * * *
0
3. Section 52.237 is amended by revising paragraph (a)(11) to read as
follows:
Sec. 52.237 Part D disapproval.
(a) * * *
(11) The contingency measures portion of the 2018 Plan for the
1997, 2006, and 2012 PM2.5 Standards (``2018
PM2.5 Plan''), adopted November 15, 2018, are disapproved
for San Joaquin Valley with respect to the 1997 annual PM2.5
NAAQS because they do not meet the requirements of Part D of the Clean
Air Act.
* * * * *
0
4. Section 52.244 is amended by adding paragraph (f)(4) to read as
follows:
Sec. 52.244 Motor vehicle emissions budgets.
* * * * *
(f) * * *
(4) San Joaquin Valley, for the 1997 annual PM2.5 NAAQS
only (years 2020 and 2023 budgets only), approved January 16, 2024.
[FR Doc. 2023-27088 Filed 12-13-23; 8:45 am]
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