[Federal Register Volume 86, Number 120 (Friday, June 25, 2021)]
[Rules and Regulations]
[Pages 33528-33539]
[FR Doc No: 2021-13608]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R09-OAR-2019-0709; FRL-10025-14-Region 9]

Approval of Air Quality Implementation Plans; California; Eastern
Kern; 8-Hour Ozone Nonattainment Area Requirements

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: The Environmental Protection Agency (EPA) is taking final
action to approve, or conditionally approve, all or portions of three
state implementation plan (SIP) revisions submitted by the State of
California to meet Clean Air Act (CAA or ``the Act'') requirements for
the 2008 8-hour ozone national ambient air quality standards (NAAQS or
``standards'') in the Eastern Kern, California (``Eastern Kern'') ozone
nonattainment area. In this action, the EPA refers to these submittals
collectively as the ``2017 Eastern Kern Ozone SIP.'' The 2017 Eastern
Kern Ozone SIP addresses certain nonattainment area requirements for
the 2008 ozone NAAQS, including the requirements for an emissions
inventory, attainment demonstration, reasonable further progress,
reasonably available control measures, contingency measures, among
others; and establishes motor vehicle emissions budgets. The EPA is
taking final action to approve the 2017 Eastern Kern Ozone SIP as
meeting all the applicable ozone nonattainment area requirements except
for the contingency measure requirement, for which the EPA is taking
final action to conditionally approve, and the reasonably available
control measures and attainment demonstration requirements, for which
the EPA is deferring action at this time.

DATES: This rule will be effective on July 26, 2021.

ADDRESSES: The EPA has established a docket for this action under
Docket ID No. EPA-R09-OAR-2019-0709. 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 disabilities who needs a reasonable
accommodation at no cost to you, please contact the person identified
in the FOR FURTHER INFORMATION CONTACT section.

FOR FURTHER INFORMATION CONTACT: John Ungvarsky, Air Planning Office
(AIR-2), EPA Region IX, 75 Hawthorne Street, San Francisco, CA 94105,
(415) 972-3963 or<EMAIL_ADDRESS>
SUPPLEMENTARY INFORMATION:

Table of Contents

I. Summary of the Proposed Action
II. Public Comments and EPA Responses
III. Final Action
IV. Statutory and Executive Order Reviews

I. Summary of the Proposed Action

    On October 28, 2020, the EPA proposed to approve, under Clean Air
Act (CAA) section 110(k)(3), and to conditionally approve, under CAA
section 110(k)(4), all or portions of three submittals from the
California Air Resources Board (CARB) and the Eastern Kern Air
Pollution Control District (EKAPCD or ``District'') as revisions to the
California SIP for the Eastern Kern ozone nonattainment area.\1\ The
three SIP revisions include the ``2017 Ozone Attainment Plan For 2008
Federal 75 ppb 8-Hour Ozone Standard'' (``Eastern Kern 2017 Ozone
Plan''),\2\ the Eastern Kern portion of the ``2018 Updates to the
California State Implementation Plan'' (``2018 SIP Update''),\3\ and
the ``Transportation Conformity Budget State Implementation Plan Update
for the Eastern Kern 2017 Ozone Attainment Plan'' (``2020 Conformity
Budget Update'').\4\ Collectively, we refer to the relevant portions of
the three SIP revisions as the ``2017 Eastern Kern Ozone SIP,'' and we
refer to our October 28, 2020 proposed rule as the ``proposed rule.''
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    \1\ 85 FR 68268. Eastern Kern is located on the western edge of
the Mojave Desert, separated from populated valleys and coastal
areas to the west and south by several mountain ranges. For a
precise description of the geographic boundaries of the Eastern Kern
ozone nonattainment area, see 40 CFR 81.305.
    \2\ Submitted by letter dated October 25, 2017, from Richard W.
Corey, Executive Officer, CARB, to Alexis Strauss, Acting Regional
Administrator, EPA Region IX.
    \3\ Submitted electronically on December 11, 2018 as an
attachment to a letter dated December 5, 2018 from Richard W. Corey,
Executive Officer, CARB, to Mike Stoker, Regional Administrator, EPA
Region IX.
    \4\ Submitted electronically on August 31, 2020, as an
attachment to a letter dated August 25, 2020, from Richard W. Corey,
Executive Officer, CARB, to John Busterud, Regional Administrator,
EPA Region IX.
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    In our proposed rule, we provided background information on the
ozone standards,\5\ area designations, related SIP revision
requirements under the CAA, and the EPA's implementing regulations for
the 2008 ozone standards, referred to as the 2008 Ozone SIP
Requirements Rule (``2008 Ozone SRR''). To summarize, at the time of
our proposed rule, the Eastern Kern ozone nonattainment area was
classified as ``Serious'' for the 2008 ozone NAAQS, and the 2017
Eastern Kern Ozone SIP was developed to address the statutory and
regulatory requirements for revisions to the SIP for the Eastern Kern
Serious ozone nonattainment area.\6\
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    \5\ Ground-level ozone pollution is formed from the reaction of
volatile organic compounds (VOC) and oxides of nitrogen
(NOX) in the presence of sunlight. The 1-hour ozone NAAQS
is 0.12 parts per million (ppm) (one-hour average), the 1997 ozone
NAAQS is 0.08 ppm (eight-hour average), and the 2008 ozone NAAQS is
0.075 ppm (eight-hour average). CARB refers to reactive organic
gases (ROG) in some of its ozone-related submittals. The CAA and the
EPA's regulations refer to VOC, rather than ROG, but both terms
cover essentially the same set of gases. In this final rule, we use
the term (VOC) to refer to this set of gases.
    \6\ On May 15, 2021, CARB requested that the EPA voluntarily
reclassify Eastern Kern to ``Severe'' for the 2008 ozone NAAQS, and
we approved the reclassification to Severe on June 7, 2021 (86 FR
30204), with a new attainment date of July 20, 2027.
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    In our proposed rule, we also discussed a decision issued by the
D.C. Circuit Court of Appeals in South Coast Air Quality Management
Dist. v. EPA (``South Coast II'') \7\ that vacated certain portions of
the EPA's 2008 Ozone SRR. The only aspect of the South Coast II
decision that affects this action is the vacatur of the provision in
the 2008 Ozone SRR that allowed states to use an alternative baseline
year for demonstrating reasonable further progress (RFP). To address
this, in the 2018 SIP Update, CARB submitted an updated RFP
demonstration that relied on a 2011 baseline year as required.\8\
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    \7\ South Coast Air Quality Management Dist. v. EPA, 882 F.3d
1138 (D.C. Cir. 2018). The term ``South Coast II'' is used in
reference to the 2018 court decision to distinguish it from a
decision published in 2006 also referred to as ``South Coast.'' The
earlier decision involved a challenge to the EPA's Phase 1
implementation rule for the 1997 ozone standard. South Coast Air
Quality Management Dist. v. EPA, 472 F.3d 882 (D.C. Cir. 2006).
    \8\ In a letter dated December 18, 2019, from Richard W. Corey,
Executive Officer, CARB, to Michael Stoker, Regional Administrator,
EPA Region 9, CARB requested withdrawal of the RFP demonstration
included in the Eastern Kern 2017 Ozone Plan submitted in October
2017. The RFP demonstration in the 2018 SIP Update replaced the
demonstration in the Eastern Kern 2017 Ozone Plan.
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    For our proposed rule, we reviewed the various SIP elements
contained in the 2017 Eastern Kern Ozone SIP (other than the reasonably
available control measures (RACM) demonstration or the attainment
demonstration), evaluated them for compliance with statutory and
regulatory requirements, and concluded that they meet all applicable
requirements, except for the contingency measure requirement, for which
the EPA proposed conditional approval. More specifically, in our
proposal rule, we based our proposed actions on the following
determinations:
     CARB and the District met all applicable procedural
requirements for public notice and hearing prior to the adoption and
submittal of the Eastern Kern 2017 Ozone Plan, 2018 SIP Update, and
2020 Conformity Budget Update (see 85 FR 68271 from the proposed rule);
     The 2012 base year emissions inventory from the Eastern
Kern 2017 Ozone Plan is comprehensive, accurate, and current and
thereby meets the requirements of CAA sections 172(c)(3) and 182(a)(1)
and 40 CFR 51.1115 for the 2008 ozone NAAQS. Additionally, the future
year baseline projections reflect appropriate calculation methods and
the latest planning assumptions and are properly supported by the SIP-
approved stationary and mobile source measures (see 85 FR 68271-68273,
68274-68276 from the proposed rule);
     The emissions statement element of the Eastern Kern 2017
Ozone Plan, including District Rule 108.2 (``Emission Statement
Requirements'') meets the requirements for emissions statements under
CAA section 182(a)(3)(B) and 40 CFR 51.1102 for the 2008 ozone NAAQS
(see 85 FR 68273-68274 from the proposed rule);
     The 15 percent rate-of-progress (ROP) demonstration
element in the Eastern Kern 2017 Ozone Plan meets the requirements of
CAA section 182(b)(1) for the Eastern Kern ozone nonattainment area for
the 2008 ozone NAAQS based on the previously-approved ROP demonstration
for the

Eastern Kern \9\ 1-hour ozone nonattainment area (see 85 FR 68274-68276
from the proposed rule);
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    \9\ See Eastern Kern 2017 Ozone Plan, 33, and 62 FR 1150, 1172
(January 8, 1997); clarified at 84 FR 45422 (August 29, 2019).
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     The RFP demonstration in the 2018 SIP Update, as corrected
in the 2020 Conformity Budget Update, provides for emissions reductions
of VOC or NOX of at least 3 percent per year on average for
each three-year period from a 2011 baseline year through the attainment
year and thereby meets the requirements of CAA sections 172(c)(2) and
182(c)(2)(B), and 40 CFR 51.1110(a)(2)(ii) for the 2008 ozone NAAQS
(see 85 FR 68274-68276 from the proposed rule);
     The motor vehicle emissions budgets in the 2020 Conformity
Budget Update for the RFP milestone/attainment year of 2020 are
consistent with the RFP demonstration, are clearly identified and
precisely quantified, and meet all other applicable statutory and
regulatory requirements in 40 CFR 93.118(e), including the adequacy
criteria in 40 CFR 93.118(e)(4) and (5) (see 85 FR 68279-68280 from the
proposed rule); and
     Through previous EPA approvals of the 1993 Photochemical
Assessment Monitoring Station SIP revision and the ``Annual Network
Plan Covering Monitoring Operations in 25 California Air Districts,
July 2019'' with respect to the Eastern Kern element,\10\ we find that
the enhanced monitoring requirements under CAA section 182(c)(1) and 40
CFR 51.1102 for Eastern Kern have been met with respect to the 2008
ozone NAAQS (see 85 FR 68280-68282 from the proposed rule).\11\
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    \10\ Letter dated November 26, 2019, from Gwen Yoshimura,
Manager, Air Quality Analysis Office, EPA Region IX, to Ravi
Ramalingam, Chief, Consumer Products and Air Quality Assessment
Branch, Air Quality Planning and Science Division, CARB.
    \11\ In the proposed rule, we found that the clean fuels fleet
program requirement in CAA sections 182(c)(4) and 246 and 40 CFR
51.1102 had been met in Eastern Kern through previous EPA approval
of the 1994 ``Opt-Out Program'' SIP revision. Upon reconsideration,
we now recognize that the clean fuels fleet program requirement does
not apply to Eastern Kern as a reclassified Serious nonattainment
area for the 2008 ozone NAAQS because the 1980 population of Eastern
Kern was below 250,000, and as such, the area does not meet the
population-based applicability threshold for the requirement under
CAA section 246(a)(3).
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    In our proposed rule, in light of the Bahr decision,\12\ we
determined that the contingency measures element of the 2017 Eastern
Kern Ozone SIP could not be fully approved without supplementation by
the District and CARB. However, we also determined that the element
could be conditionally approved as meeting the requirements of CAA
sections 172(c)(9) and 182(c)(9) for the 2008 ozone NAAQS, based upon
commitments by the District \13\ and CARB \14\ to supplement the
element through submission, as a SIP revision (within one year of our
final conditional approval action), of a revised District rule or rules
that would add new limits or other requirements if an RFP milestone is
not met or if Eastern Kern fails to attain the 2008 ozone NAAQS by the
applicable attainment date. See 85 FR 68276-68279 from the proposed
rule.
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    \12\ Bahr v. EPA, 836 F.3d 1218 (9th Cir. 2016) (``Bahr'')
(rejecting early-implementation of contingency measures and
concluding that a contingency measure under CAA section 172(c)(9)
must take effect at the time the area fails to make RFP or attain by
the applicable attainment date, not before).
    \13\ Letter dated September 1, 2020, from Glen E. Stephens, Air
Pollution Control Officer, EKAPCD, to Richard Corey, Executive
Officer, CARB.
    \14\ Letter dated September 18, 2020, from Richard W. Corey,
Executive Officer, CARB, to John Busterud, Regional Administrator,
EPA Region IX.
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    Please see our proposed rule for more information concerning the
background for this action and for a more detailed discussion of the
rationale for approval or conditional approval of the above-listed
elements of the 2017 Eastern Kern Ozone SIP.

II. Public Comments and EPA Responses

    The public comment period on the proposed rule opened on October
28, 2020, the date of its publication in the Federal Register, and
closed on November 27, 2020. During this period, the EPA received one
comment letter submitted by Air Law for All on behalf of the Center for
Biological Diversity (referred to herein as ``CBD'' or ``commenter'').
We address CBD's comments in the following paragraphs of this final
rule.
    Comment #1: Citing certain statutory provisions and selected
excerpts from the EPA's implementation rules for the 1997 and 2008
ozone NAAQS, CBD asserts that, for Serious areas, the RFP demonstration
must meet both the general RFP requirements in section 172(c)(2) that
are tied to attainment of the ozone standards and the specific RFP
requirements in section 182(c)(2)(B) for reductions in emissions of
VOCs from baseline emissions. In short, CBD contends that the RFP
``targets'' cannot be severed from the attainment demonstration and
control strategy and independently approved, and because the EPA has
not proposed to approve an attainment demonstration and control
strategy for the Eastern Kern nonattainment area, there is no basis to
conclude that the RFP demonstration in the 2017 Eastern Kern Ozone SIP
meets the general RFP requirements in section 172(c)(2).
    Response to Comment #1: As CBD notes, Serious ozone nonattainment
areas are subject to both the general requirements for nonattainment
plans in subpart 1, and the specific requirements for ozone areas in
subpart 2, including the requirements related to RFP and attainment.
This is consistent with the structure of the CAA as modified under the
1990 amendments, which introduced additional subparts to part D of
title I of the CAA to address requirements for specific NAAQS
pollutants, including ozone (subpart 2), carbon monoxide (CO) (subpart
3), particulate matter (subpart 4), and sulfur oxides, nitrogen
dioxide, and lead (subpart 5).
    These subparts apply tailored requirements for these pollutants,
including those based on an area's designation and classification, in
addition to and often in place of the generally applicable provisions
retained in subpart 1. While CAA section 172(c)(2) of subpart 1 states
only that nonattainment plans ``shall require reasonable further
progress,'' CAA sections 182(b)(1) and 182(c)(2)(B) of subpart 2
provide specific percent reduction targets for ozone nonattainment
areas to meet the RFP requirement. Put another way, subpart 2 further
defines RFP for ozone nonattainment areas by specifying the incremental
amount of emissions reduction required by set dates for those
areas.\15\ For Moderate ozone nonattainment areas, CAA section
182(b)(1) defines RFP by setting a specific 15% VOC reduction
requirement over the first six years of the plan. For Serious and above
ozone nonattainment areas, CAA section 182(c)(2)(B) defines RFP by
setting specific annual percent reductions for the period following the
first six-year period and allows averaging over a 3-year period. With
respect to the 1-hour ozone NAAQS, the EPA stated that, by meeting the
specific percent reduction requirements in CAA sections 182(b)(1) and
182(c)(2)(B), the State will also

satisfy the general RFP requirements of section 172(c)(2) for the time
period discussed.\16\
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    \15\ CAA section 171(1) defines reasonable further progress as
``such annual incremental reductions in emissions of the relevant
air pollutant as are required by this part or may reasonably be
required by the Administrator for the purpose of ensuring attainment
of the applicable national ambient air quality standard by the
applicable date.'' The words ``this part'' in the statutory
definition of RFP refer to part D of title I of the CAA, which
contains both the general requirements in subpart 1 and the
pollutant-specific requirements in subparts 2-5 (including the
ozone-specific RFP requirements in CAA sections 182(b)(1) and
182(c)(2)(B) for Serious areas).
    \16\ 57 FR 13498, at 13510 (Moderate areas) and at 13518
(Serious areas) (April 16, 1992).
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    We agree with CBD that the EPA has adapted the RFP requirements
under the CAA to implement the three 8-hour-average ozone NAAQS that
have been promulgated since the 1990 CAA Amendments. In the ``Phase 2''
SIP Requirements Rule \17\ for the 1997 Ozone NAAQS (``Phase 2 rule''),
the Agency adapted the RFP requirements of CAA sections 172(c)(2) and
182(a)(1) so as to require plans to provide for the minimum required
percent reductions and, for certain Moderate areas, to provide for the
reductions as necessary for attainment. See, e.g., 40 CFR
51.910(a)(1)(ii)(A) and (b)(2)(ii)(C).
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    \17\ 70 FR 71612 (November 29, 2005).
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    In 2015, the EPA replaced the regulations promulgated through the
Phase 2 rule with the regulations promulgated through the 2008 Ozone
SIP Requirements Rule (SRR).\18\ In the 2008 Ozone SRR, the EPA
established RFP requirements for the 2008 ozone NAAQS that are similar,
in most respects, to those in the Phase 2 rule for the 1997 ozone NAAQS
but that do not carry forward the aspect of the RFP requirement for the
1997 ozone NAAQS that defined RFP for certain years for certain
Moderate areas in terms of the reductions needed for attainment.\19\
More explicitly, in the 2008 Ozone SRR, the EPA defined RFP as meaning
both the ``emissions reductions required under CAA section 172(c)(2)
which the EPA interprets to be an average 3 percent per year emissions
reductions of either VOC or NOX and CAA sections 182(c)(2)(B) and
(c)(2)(C) and the 15 percent reductions over the first six years of the
plan and the following three percent per year average under 40 CFR
51.1110.'' \20\ (emphasis added). Thus, under the 2008 Ozone SRR, the
RFP emissions reductions required for Serious and above ozone
nonattainment areas under CAA section 172(c)(2) are based on a set
annual percentage found in the CAA, not on the specific attainment
needs for the area. In this regard, we have been even more explicit in
our SRR for the 2015 ozone NAAQS: \21\ ``Reasonable further progress
(RFP) means the emissions reductions required under CAA sections
172(c)(2), 182(c)(2)(B), 182(c)(2)(C), and Sec.  51.1310. The EPA
interprets RFP under CAA section 172(c)(2) to be an average 3 percent
per year emissions reduction of either VOC or NOX.'' \22\
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    \18\ 80 FR 12264 (March 6, 2015). Under 40 CFR 51.919 and
51.1119, the regulations promulgated through the 2008 Ozone SRR
replaced the regulations promulgated through the Phase 2 rule, with
certain exceptions not relevant here.
    \19\ Compare the RFP requirements for the 1997 ozone NAAQS at 40
CFR 51.910(a)(1)(ii)(A) and (b)(2)(ii)(C) with the analogous
provisions for the 2008 ozone NAAQS at 40 CFR 51.1110(a)(2)(i)(B).
    \20\ 40 CFR 51.1100(t).
    \21\ 83 FR 62998 (December 6, 2018).
    \22\ 40 CFR 51.1300(l).
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    In the 2008 Ozone SRR, which is the set of regulations that governs
the EPA's action here, RFP is defined in terms of percent reduction
requirements, not in terms of the reductions necessary for attainment.
In other words, for the 2008 ozone NAAQS, the RFP ``targets'' represent
the minimum progress that is required under the CAA and our
regulations, not necessarily all of the reductions necessary to achieve
attainment of the ozone NAAQS, which could vary largely from one
nonattainment area to another.
    Eastern Kern is a Serious nonattainment area for the 2008 ozone
NAAQS, and the RFP demonstration in the 2017 Eastern Kern Ozone SIP was
developed to meet the applicable requirements of the CAA and our 2008
Ozone SRR, not the Phase 2 rule for the 1997 ozone NAAQS. Specifically,
we reviewed the RFP demonstration in the 2017 Eastern Kern Ozone SIP
for compliance with the requirements under 40 CFR 51.1110(a)(2)(i),
which adapts the requirements under CAA sections 172(c)(2) and
182(b)(1) for Moderate areas, and 40 CFR 51.1110(a)(2)(ii), which
adapts the requirements of CAA section 182(c)(2)(B) for Serious
areas.\23\ The requirements under 40 CFR 51.1110(a)(2)(i) and 40 CFR
51.1110(a)(2)(ii) are cumulative and, together, they require a 15
percent emission reduction from the baseline year within 6 years after
the baseline year and an average emissions reduction of 3 percent per
year for all remaining 3-year periods after the first 6-year period
until the year of the area's attainment date. As explained further in
our proposed rule, based on our evaluation, we found that the 2017
Eastern Kern Ozone SIP provided for the percent reductions required
under the 2008 Ozone SRR.\24\
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    \23\ 40 CFR 51.1110(a)(2) applies to Eastern Kern because
Eastern Kern is an area with an approved 1-hour ozone NAAQS 15
percent VOC Rate of Progress (ROP) plan.
    \24\ 85 FR 68268, at 68274-68276.
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    Importantly, under the 2008 Ozone SRR, the RFP demonstration for
the 2008 ozone NAAQS does not need to provide for the reductions needed
for attainment. Thus, contrary to CBD's assertion, the RFP
demonstration for Eastern Kern can be severed from the attainment
demonstration and control strategy and can be independently approved,
and we do so in this final rule by taking final action to approve the
RFP demonstration in the 2017 Eastern Kern Ozone SIP while deferring
action on the attainment demonstration.
    Comment #2: CBD comments that the submittal fails to show that the
substitute NOX emissions reductions will ``result in a
reduction in ozone concentrations at least equivalent'' to the required
three percent per annum VOC emissions reductions, and as a result, the
EPA's proposed approval of the RFP demonstration is arbitrary and
capricious.
    The commenter describes the relative roles of VOC and
NOX in ozone formation, including the existence of an
``optimum'' VOC to NOX ratio for a given level of VOC (i.e.,
a NOX concentration at which the maximum amount of ozone is
produced). As explained by the commenter, in a ``NOX
saturated'' situation where NOX levels exceed this optimum
ratio, a reduction in NOX emissions can lead to increases in
ozone levels, whereas in a ``NOX limited'' situation with
NOX levels below the optimum ratio, a reduction in
NOX emissions decreases ozone levels. The commenter quotes
the EPA's report to Congress as including, ``ozone response to
precursor control can vary greatly with each area'' and ``the relative
effectiveness of controls of volatile organic compounds (VOCs) and
oxides of nitrogen (NOX) in ozone abatement varies widely.''
\25\ The commenter argues that language in the CAA, including CAA
sections 185B, 182(f), and 182(c)(2)(C), indicates that Congress was
aware of the issue of the relative roles of NOX and VOC in
ozone formation, including that in some scenarios NOX
reductions may actually increase ozone concentrations or at least not
help to reduce ozone concentrations.
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    \25\ Excerpt from CBD comments (see page 10) citing ``The Role
of Ozone Precursors in Tropospheric Ozone Formation and Control: A
Report to Congress,'' EPA-454/R-93-024, at 2-2 (July 1993), EPA
Office of Air Quality Planning and Standards (report to Congress
mandated by section 185B, 42 U.S.C. 7511f).
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    The commenter then points to the EPA's consideration of the
relative effectiveness of NOX and VOC controls for
interpollutant offset trading under the new source review (NSR)
permitting program and in applying requirements for major stationary
sources of VOC to NOX sources under CAA section 182(f),
noting that in these situations EPA guidance indicates that
photochemical grid modeling of multiple scenarios should be conducted
to support demonstrations related to the relative

effectiveness of controls. Through comparison of the contexts of these
guidance documents, which recommended photochemical modeling, and that
of section 182(c)(2)(C), the commenter suggests that the 2017 Eastern
Kern Ozone SIP should have included similar photochemical grid modeling
to determine whether the substitute NOX emission reductions
result in equivalent ozone reductions.
    Response to Comment #2: In general, we agree with the commenter's
descriptions of the relative roles of VOC and NOX in ozone
formation and geographic differences in the ozone response to precursor
control, depending on whether an area is ``NOX-saturated''
or ``NOX-limited.'' We also agree with the commenter that
Congress was aware of these issues and provided for the EPA to address
them under provisions of the CAA.
    However, we disagree with the commenter's characterization of the
2017 Eastern Kern Ozone SIP and the EPA's proposed approval. While the
preamble of the EPA's proposed approval did not provide an analysis
showing that NOX substitution would ``result in a reduction
in ozone concentrations at least equivalent'' to the required VOC
emissions reductions needed for RFP, the supporting documentation in
the docket for the proposed approval, as further clarified in our
response to comments herein, provides such analysis. As described
below, we find that the analysis included with the modeling and control
strategy in the 2017 Eastern Kern Ozone SIP adequately demonstrates
that annual and cumulative NOX reductions in Eastern Kern
will result in a reduction in ozone concentrations that is at least
equivalent to the ozone reductions that would be achieved by VOC
emission reductions alone. We therefore agree with the use of
NOX substitution in the RFP demonstration for Eastern Kern.
    Under CAA section 182(c)(2)(B), the RFP demonstration for a Serious
ozone nonattainment area will demonstrate RFP based solely on the
prescribed annual rate of VOC emission reductions. Alternatively, under
CAA section 182(c)(2)(C), the demonstration may satisfy the RFP
requirement based on a combination of VOC and NOX reductions
if it demonstrates that reductions of VOC and NOX would
result in a reduction in ozone concentrations at least equivalent to
that which would result from the amount of VOC emission reductions
otherwise required. For Eastern Kern, the RFP demonstration for
milestone years 2017 and 2020 both rely on a combination of VOC
reductions and NOX reductions from the RFP baseline year of
2011.
    The revised RFP demonstration in the 2018 SIP Update, as corrected
in the 2020 Conformity Budget Update, shows the extent to which the
area is relying on NOX emissions reductions to substitute
for otherwise-required VOC reductions in milestone years 2017 and 2020.
For milestone year 2017, the RFP demonstration relies on a combination
of 1.4 tons per day (tpd) VOC reductions and 0.4 tpd NOX
reductions from the 2011 RFP baseline year rather than the otherwise-
required VOC reductions of 1.6 tpd. That is, 0.4 tpd of NOX
reductions substitutes for 0.2 tpd of VOC reductions otherwise
required, which represents a 2:1 ratio for substitution of
NOX for VOC in RFP milestone year 2017. This substitution of
NOX reductions for VOC reductions is acceptable under CAA
section 182(c)(2)(C) so long as the ozone concentration reductions from
2011 to 2017 in Eastern Kern under the combined VOC/NOX
emissions reduction scenario are at least equivalent to that which
would result under the VOC-only reduction scenario.
    The same applies to milestone year 2020. For that year, the RFP
demonstration relies on a combination of 1.5 tpd VOC reductions and 3.1
tpd NOX reductions from the 2011 RFP baseline year rather
than the otherwise-required VOC reductions of 2.3 tpd. That is, 3.1 tpd
of NOX reductions substitutes for 0.8 tpd of VOC reductions
otherwise required, which means that NOX is substituted for
VOC in RFP milestone year 2020 at roughly a 4:1 ratio. Again, this
substitution of NOX reductions for VOC reductions is
acceptable under CAA section 182(c)(2)(C) so long as the ozone
concentration reductions from 2011 to 2020 in Eastern Kern under the
combined VOC/NOX emissions reduction scenario are at least
equivalent to that which would result under the VOC-only reduction
scenario.
    The 2017 Eastern Kern Ozone SIP contains a demonstration supporting
the use of NOX substitution in the Eastern Kern
nonattainment area. This is based on evidence that the Eastern Kern
nonattainment area is NOX-limited, and also on evidence that
NOX reductions are more effective at reducing ozone than VOC
reductions alone. In this notice, we use ``NOX-limited'' as
meaning a situation where reducing NOX emissions decreases
ozone, not that it is more effective than reducing VOC. Elsewhere,
including in the 2017 Eastern Kern Ozone SIP, the term
``NOX-limited'' is sometimes used to mean the condition
where NOX reductions are more effective than VOC reductions
at decreasing ozone.
    Evidence that the Eastern Kern nonattainment area is
NOX-limited is presented in Figure 14 in Appendix F of the
Eastern Kern 2017 Ozone Plan. Figure 14 and the explanatory text
document weekday and weekend monitored ozone data at the Mojave
monitoring site from 2000-2015.\26\ The results show that in nearly all
years, weekdays with their higher NOX emissions have
increased ozone, while weekends with their lower NOX, have
decreased ozone. Figure 14 includes a 1:1 line on which weekday and
weekend ozone are the same.\27\ Of the sixteen years examined, thirteen
are above the 1:1 line, indicating higher weekday ozone and
NOX-limited ozone formation. All years after 2007 are above
the 1:1 line. The three years (i.e., 2001, 2003, and 2007) below the
1:1 line indicate slightly higher ozone from reducing NOX.
However, all three of those years are in the ``transitional'' regime
close to the 1:1 line; this indicates the three years have only a weak
ozone response to NOX reductions, as opposed to a
disbenefit. This data analysis is strong evidence that ozone formation
is NOX-limited in the Eastern Kern nonattainment area.
---------------------------------------------------------------------------

    \26\ Eastern Kern 2017 Ozone Plan, Appendix F, F-42--F-43; and
Appendix H, H-22--H-23.
    \27\ Id.
---------------------------------------------------------------------------

    The Eastern Kern 2017 Ozone Plan also included photochemical
modeling results reflecting base year (2012) emissions and meteorology.
The weekday-weekend analysis discussed above was repeated for modeled
concentrations, which were found to be ``NOX-limited.'' \28\
The degree of NOX-limitation, that is the response of ozone
to NOX emissions reductions, was found to be comparable to
and somewhat greater than that in the ambient data. Given the Eastern
Kern 2017 Ozone Plan's usage of the term ``NOX-limited,''
the photochemical modeling also indicates that NOX
reductions are more effective than VOC at reducing ozone.\29\
---------------------------------------------------------------------------

    \28\ Eastern Kern 2017 Ozone Plan, Appendix F, Figure 14, F-42.
    \29\ The use of ``NOX-limited'' in the 2017 Eastern
Kern Ozone SIP is mainly consistent with NOX reductions
being more effective than VOC reductions, i.e., ``NOX-
limited'' in a relative sense rather than the strict sense of ozone
decreasing with NOX reductions. See Appendix F of the
Eastern Kern 2017 Ozone Plan: ``(NOX-limited region in
Figure 13), ozone formation shows a benefit to reductions in
NOX emissions, while changes in ROG emissions result in
only minor decreases in ozone,'' F-40; in Figure 13, the
``NOX-limited'' region is one with isopleth lines nearly
parallel to the VOC axis, indicating little change in ozone as VOC
changes, and relatively large changes in ozone as NOX
changes, F-41; ``This region [Eastern Kern] is in close proximity to
biogenic ROG emissions sources and farther away from the
anthropogenic NOX sources, such that low NOX
and high ROG reactivity conditions are prevalent, which is
consistent with the region being in a NOX-limited
regime,'' F-42. The CARB Staff Report on the Eastern Kern 2017 Ozone
Plan (see A-9 of the Staff Report) refers to NOX-limited
conditions as discussed in Finlayson-Pitts and Pitts, 1993, p.1093,
whose use of ``NOX-limited'' is consistent with both the
relative and strict senses of the term, but given its context of
``control of VOCs versus NOX,'' is more relevant to the
relative sense.

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

    For a percentage-based NOX substitution to result in an
equivalent ozone reduction, ozone formation must not only be
NOX-limited, but also NOX reductions must be at
least as effective at reducing ozone as VOC reductions. In the 2017
Eastern Kern Ozone SIP, CARB and the District concluded that ozone
formation is ``NOX-limited,'' but again, they use that term
to mean that NOX reductions are more effective than VOC
reductions. That conclusion was based not only on the weekday-weekend
evidence of NOX limitation but also on additional
information, as described in the following paragraphs.
    The 2017 Eastern Kern Ozone SIP also provides ample documentation
that high ozone concentrations in Eastern Kern are mainly due to
transport from the San Joaquin Valley (SJV) to the northwest and
sometimes from the South Coast Air Basin (SCAB) to the southwest.\30\
Further, NOX and VOC emissions in the western Kern County
portion of the SJV are respectively 2.5 and 8 times those within
Eastern Kern; NOX and VOC emissions in the Los Angeles
County portion of SCAB are respectively 10 and 37 times those within
Eastern Kern.\31\ Eastern Kern is downwind of large urban areas, and
CARB noted in the 2017 Eastern Kern Ozone SIP the recognized phenomenon
that locations downwind of major urban areas have high
VOC:NOX ratios and consequently are more sensitive to
NOX reduction than to VOC. The VOC:NOX ratio of
an urban air mass tends to increase as it moves downwind, since there
is less input of NOX emissions from combustion sources but
continued VOC emissions input from biogenic sources, and also
NOX gets preferentially removed by other chemical and
physical processes.\32\ In Eastern Kern, biogenic VOC emissions are 10
times as high as anthropogenic VOC in 2005 and upwards of 20 times as
high during peak biogenic years,\33\ which also tends to increase the
VOC:NOX ratio in Eastern Kern. EKAPCD estimated biogenic VOC
emissions to be 169 tpd during the period of 2012 through 2020,\34\
which is over five times the total baseline NOX inventories
used in the RFP demonstration in Table 3.\35\ CARB states in the 2017
Eastern Kern Ozone SIP that ``This region is in close proximity to
biogenic ROG emissions sources and farther away from the large
anthropogenic NOX sources in the SJVAB and SCAB, such that
low NOX and high ROG conditions are prevalent, which is
consistent with a NOX-limited regime.'' \36\ While some of
this evidence could be termed qualitative, the EPA finds that it makes
a compelling case that NOX emissions reductions are more
effective than VOC reduction at decreasing ozone in Eastern Kern, and
therefore that percentage-based NOX substitution results in
ozone reductions at least equivalent to those that would result from
the VOC reductions required for RFP.
---------------------------------------------------------------------------

    \30\ Eastern Kern 2017 Ozone Plan, Appendix H, H-8--H-15; CARB
Staff Report on the Eastern Kern 2017 Ozone Plan, A-5.
    \31\ Eastern Kern 2017 Ozone Plan, Appendix H, H-20.
    \32\ The VOC:NOX ratio increases due to chemical
conversion to HNO3 and due to the process of deposition
to surfaces, which removes NOX (in the form of
HNO3) from the air more quickly than VOC. Barbara J.
Finlayson-Pitts and James N. Pitts Jr., 1993, ``Atmospheric
Chemistry of Tropospheric Ozone Formation: Scientific and Regulatory
Implications,'' Journal of the Air and Waste Management Association,
43:8, 1091-1100, https://doi.org/10.1080/1073161X.1993.10467187;
cited in CARB Staff Report, p. A-9.
    \33\ Eastern Kern 2017 Ozone Plan, Appendix H, H-21.
    \34\ Eastern Kern 2017 Ozone Plan, Table 14, 37.
    \35\ 85 FR 68268, 68275-68276.
    \36\ Eastern Kern 2017 Ozone Plan, Appendix H, H-22. As already
noted, the 2017 Eastern Kern Ozone SIP primarily uses
``NOX-limited'' to mean NOX reduction are more
effective than VOC reductions. ``SJVAB'' is an acronym for the San
Joaquin Valley Air Basin.
---------------------------------------------------------------------------

    The 2017 Eastern Kern Ozone SIP clearly documents that the Eastern
Kern nonattainment area is strongly affected by transport of ozone from
the SJV and SCAB.\37\ Although the EPA's proposed action did not
discuss in detail the impact of transport on RFP, we are providing
additional technical information to further clarify the relationship
between transport from the SJV and SCAB and ozone formation in the
Eastern Kern nonattainment area.
---------------------------------------------------------------------------

    \37\ CARB Staff Report on the Eastern Kern 2017 Ozone Plan, A-9,
A-13--A-18.
---------------------------------------------------------------------------

    Photochemical modeling results in the ``2016 Ozone Plan for 2008 8-
Hour Ozone Standard for the San Joaquin Valley'' (``SJV 2016 Ozone
Plan'') \38\ and analyses of the San Joaquin Valley portion of the
``2018 Updates to the California State Implementation Plan'' (``2018
SIP Update'') \39\ also support the conclusion that NOX
reductions are more effective than VOC at reducing ozone in the Eastern
Kern nonattainment area. The EPA approved a modeled attainment
demonstration for the SJV 2016 Ozone Plan that used the same
meteorological and photochemical models, model domains, and setup
parameters, and covered the same 2012 ozone season as the Eastern Kern
modeling.\40\ The SJV 2016 Ozone Plan contained an ozone isopleth
diagram for the Clovis monitor,\41\ the SJV site with the highest ozone
design value in 2031. In support of the 2018 SIP Update, CARB provided
supplemental documentation that used the isopleth diagram to show that
the SJV attainment demonstration remained valid.\42\ As part of the
EPA's approval of the SJV portion of the 2018 SIP Update,\43\ the EPA
used the ozone isopleth diagram to estimate the sensitivity of ozone to
VOC and NOX emissions reductions.\44\ We determined that
ozone changes by 0.313 ppb per percent change in NOX
emissions, and by 0.0234 ppb per percent change in VOC emissions.\45\
On a percentage basis, NOX is 13.4 times as effective as VOC
at reducing ozone at the Clovis monitor. The ozone response to emission
changes is expected to be similar in western Kern County because both
areas have similar meteorological conditions and a similar mix of
emissions sources.
---------------------------------------------------------------------------

    \38\ SJV 2016 Ozone Plan, San Joaquin Valley Unified Air
Pollution Control District, June 16, 2016.
    \39\ 2018 SIP Update, CARB, October 25, 2018.
    \40\ 84 FR 3302 (February 12, 2019).
    \41\ SJV 2016 Ozone Plan, Appendix H, Figure 15, H-54. Clovis is
located in Fresno County, approximately 7 miles northeast of
downtown Fresno.
    \42\ Email dated October 19, 2018, from Sylvia Vanderspek, CARB
to Anita Lee, EPA Region IX, with attachments.
    \43\ 83 FR 61346 (November 29, 2018); See also the related final
rule at 84 FR 11198 (March 25, 2019).
    \44\ ``Technical Support Document, Proposed Phase 2 Approval of
Portions of the SJV 2016 Ozone Plan and 2018 SIP Updates,'' Docket:
EPA-R09-OAR-2018-0535, EPA Region 9, November 14, 2018, including
two attachments: ``Scale attainment demonstration with updated
emissions'' and ``Effect of Updated Emissions Estimates on San
Joaquin Valley Attainment Demonstration.''
    \45\ Id.
---------------------------------------------------------------------------

    Eastern Kern is directly downwind of western Kern County. The
mountain ranges to the northwest separate sparsely populated Eastern
Kern from the more densely populated areas in the southern SJV,
including western Kern County. However, the Tehachapi pass connects the
SJV to Eastern Kern, facilitating the transport of emissions and
pollutants into the region.\46\ For the reasons discussed earlier in
this section, ozone formation in Eastern Kern is more NOX-
limited than the larger urban areas of the southern SJV and western
Kern County. Putting these together, ozone in Eastern Kern is expected
to be 13 times or more as sensitive to NOX emissions

reductions as to VOC reductions on a percentage basis.
---------------------------------------------------------------------------

    \46\ Eastern Kern 2017 Ozone Plan, H-16.
---------------------------------------------------------------------------

    In addition, the 2007 Ozone Plan for San Joaquin Valley included
isopleth diagrams for every monitoring site, including those in Kern
County, just upwind of Eastern Kern.\47\ The State used photochemical
modeling to assess the effect of NOX and VOC emissions
reductions for projected years 2020 and 2023 at every site. For every
location for both years, NOX emissions reductions were more
effective than VOC at reducing ozone. For example, the projected 2020
8-hour ozone design value at the Bakersfield-California Avenue site was
modeled to decrease from 87 to 86 ppb when VOC is reduced by 20
percent, and from 87 to 83 ppb when NOX is reduced by 20
percent. The corresponding values for 2023 are a decrease from 88 to 87
ppb for VOC, and a decrease from 88 to 84 ppb for NOX.\48\
This is additional evidence that NOX reductions are more
effective than VOC reductions in Eastern Kern.
---------------------------------------------------------------------------

    \47\ San Joaquin Valley Unified Air Pollution Control District,
``2007 Ozone Plan,'' April 30, 2007. The EPA approved the 2007 Ozone
Plan at 77 FR 12652 (March 1, 2012).
    \48\ Id. in Appendix F. Photochemical Modeling Support
Documents, F-15--F-58.
---------------------------------------------------------------------------

    Air quality in the Eastern Kern nonattainment area is also strongly
affected by ozone transport from the SCAB through the Soledad Canyon
located between Santa Clarita in the SCAB and Palmdale, south of
Eastern Kern.\49\ Santa Clarita is approximately 65 miles from the
Mojave monitor and approximately 50 miles from the southern boundary of
the nonattainment area. In the South Coast Air Quality Management
District's (SCAQMD's) ``Final 2016 Air Quality Management Plan''
(``South Coast 2016 AQMP''), SCAQMD included an isopleth for the Santa
Clarita monitoring site.\50\ The isopleths for the Santa Clarita site
clearly show that NOX reductions in the area upwind of
Eastern Kern are more effective than VOC reductions at reducing ozone.
---------------------------------------------------------------------------

    \49\ Eastern Kern 2017 Ozone Plan, Appendix F, F-15.
    \50\ South Coast 2016 AQMP, Appendix V, Attachment 4 (2031 8-
Hour Ozone Isopleths), 21; and Attachment 5 (2023 8-Hour Ozone
Isopleths), 21.
---------------------------------------------------------------------------

    The documentation associated with the Clovis and Santa Clarita
monitors, representative locations in the SJV and SCAB upwind of the
mountain passes through which ozone is transported to downwind Eastern
Kern, demonstrates that NOX reductions are more effective
than VOC reductions in the Eastern Kern nonattainment area. This
further supports the conclusion that NOX substitution
results in a reduction in ozone concentrations at least equivalent to
that which would result from the amount of VOC emission reductions
otherwise required for RFP. Even though the State's submittal lacks an
isopleth diagram specifically for the Mojave site in Eastern Kern, the
supporting documentation (i.e., Figure 14; the comparison of Eastern
Kern emissions with emissions from western Kern County and Los Angeles
County; VOC emissions from biogenic sources; and isopleths from upwind
sites in the SJV and SCAB) demonstrates that the resulting
NOX reductions here will be at least equivalent to that
which would result from VOC reductions alone, as required in section
182(c)(2)(C).
    Based on the above, we disagree with the commenter's assertion that
CAA section 182(c)(2)(C) requires the District to provide additional
photochemical grid modeling to demonstrate that the substituted
NOX reductions are at least as effective as the VOC
reductions that would otherwise be required under section 182(c)(2)(B).
    Further, we believe that the commenter's comparison to the EPA's
recommendations with respect to interpollutant trading for
nonattainment NSR permitting purposes and eligibility for an exemption
from NOX requirements under CAA 182(f) are not relevant for
NOX substitution under CAA section 182(c)(2)(C). The
guidance documents cited by the commenter for these examples are non-
binding and do not constrain the EPA's discretion to adopt a different
approach where appropriate.\51\ The documents recommend photochemical
grid modeling in some scenarios but do not require this approach or any
other specific demonstration. This reflects the EPA's acknowledgement
that the level of analysis required for any particular demonstration
related to NOX and VOC reductions will differ based on
context and local conditions, such as those noted by the commenter
regarding the relative effectiveness of controlling each. In the
context of CAA 182(c)(2)(C) and based on the EPA's responses herein, no
additional modeling or demonstration is required.
---------------------------------------------------------------------------

    \51\ See EPA, ``Guideline for Determining the Applicability of
Nitrogen Oxide Requirements under Section 182(f)'' (December 16,
1993), 1; Memorandum dated January 14, 2005, from Stephen D. Page,
Director, Office of Air Quality Planning and Standards, U.S. EPA, to
EPA Regional Air Directors, Regions I-X, Subject: ``Guidance on
Limiting Nitrogen Oxides (NOX) Requirements Related to 8-
Hour Ozone Implementation,'' 3; EPA-454/R-18-004, ``Technical
Guidance for Demonstration of Inter-Precursor Trading (IPT) for
Ozone in the Nonattainment New Source Review Program,'' Office of
Air Quality Planning and Standards (May 2018) (``IPT Guidance''), 2.
The IPT Guidance specifically excludes applicability to RFP
demonstrations. IPT Guidance at 2, n.1.
---------------------------------------------------------------------------

    Comment #3: The commenter also contends that an equivalence
demonstration under CAA section 182(c)(2)(C) must show equivalence
throughout the nonattainment area, must be quantitative, and must be as
technically rigorous as an attainment demonstration.
    First, the commenter states that because CAA section 182(c)(2)(C)
uses the plural ``ozone concentrations,'' the equivalency demonstration
must show equivalence throughout the nonattainment area, and not just
at a single monitoring site. Otherwise, there could be ozone increases
in NOX-saturated areas within the nonattainment area that
might interfere with attainment of the more stringent 2015 ozone NAAQS,
and that might result in adverse public health effects even for
locations meeting the ozone NAAQS because there is no safe level of
ozone.
    Second, the commenter criticizes the technical information in the
Eastern Kern 2017 Ozone Plan as insufficient to show that
NOX substitution will result in equivalent reductions in
ozone concentrations throughout the nonattainment area. The commenter
states that the Eastern Kern 2017 Ozone Plan submittal documents the
ozone decrease from weekend NOX reductions at a single
Mojave monitor during 2000-2015 to conclude the area is NOX-
limited, and that it makes general observations about the magnitude and
distance of emissions. The commenter states that the technical
information in the Eastern Kern 2017 Ozone Plan is merely qualitative,
whereas the word ``equivalent'' in CAA section 182(c)(2)(C) means that
the demonstration should be quantitative. The commenter also states
that the 2017 Eastern Kern Ozone SIP should consider post-2015 data,
because of post-2015 emissions changes like the replacement of
NOX combustion sources with wind and solar electricity
generation, and because of the changing geographic distribution of
emissions.
    Lastly, the commenter states that an equivalence demonstration
should be as rigorous as an attainment demonstration, which is based on
photochemical modeling or another equally rigorous technique. The
commenter suggests that the state could compare modeled relative
response factors (RRFs) for each RFP milestone year for the 3 percent
per year VOC reductions to corresponding factors from the control
strategy. Alternatively, for the demonstration, the commenter suggests
that the state could use ozone

isopleth diagrams together with conservative assumptions about the
amount of allowable NOX substitution.
    Response to Comment #3: First, we disagree that the plural
``concentrations'' in CAA section 182(c)(2)(C) necessarily means that
equivalence must be demonstrated throughout the nonattainment area.
However, in this instance, it does not matter because all locations
within the Eastern Kern nonattainment area are downwind of, and more
NOX-limited than, the SJV and the SCAB, for which
NOX reductions are more effective than VOC. Therefore,
NOX reductions are more effective than VOC for all locations
in the Eastern Kern nonattainment area.
    Second, we disagree that equivalence demonstrations necessarily
must be quantitative estimates. Analytical information that establishes
equivalence may be quantitative or qualitative, or both, depending on
the facts and circumstances of any given area. In this instance, as
discussed above, some of the evidence relied upon could be termed
qualitative, such as the known tendency for ozone formation to become
more NOX-limited with distance downwind of an urban area,
and the relative sizes of emissions inventories for Eastern Kern and
the upwind areas. This relatively qualitative evidence was coupled with
more quantitative assessments of the degree of NOX-
limitation (weekday-weekend differences). Qualitative evidence can be
just as useful as quantitative evidence. For NOX
substitution to yield an equivalent ozone decrease as required in
section 182(c)(2)(C), we only need to know that reductions of
NOX are at least as effective as reductions of VOC for
reducing ozone concentrations. Further, the estimate that
NOX emissions reductions are 13 times as effective as VOC
reductions is quantitative, not qualitative.
    With respect to post-2015 emissions changes, we note that
NOX and VOC emissions in Eastern Kern are projected to
decrease slightly after 2015 through year 2021, largely due to
reductions in mobile source emissions offsetting increases from
stationary and area sources.\52\ In the upwind areas of SJV and SCAB,
the same is true but NOX emissions are projected to decrease
at a faster rate than VOC emissions,\53\ which would have the effect of
increasing the VOC:NOX ratio, making Eastern Kern even more
NOX-limited. The emissions projections in the 2017 Eastern
Kern Ozone SIP take into account long-term trends for the various
source categories, including electricity generation. The commenter has
not cited any particular natural-gas power plant closure that would
affect the Eastern Kern area, and we are not aware of any such closure.
The possible replacement of NOX-producing electricity
generation by wind and solar power cited by the commenter would also
tend to make the area more NOX-limited. The geographic
distribution of the emissions changes is also not of concern. Emissions
from the upwind areas are channeled through a small set of mountain
passes regardless of their precise upwind location. Emissions within
Eastern Kern itself are so much lower than those of the upwind areas
that their particular location within the nonattainment area does not
affect the NOX-limited conditions there. Because the
VOC:NOX ratio of emissions input to the model increases
between 2012 and 2020, if additional modeling were carried out using
2020 emissions, it is expected that ozone formation would be even more
NOX-limited.\54\ Thus neither the magnitude nor the
geographic distribution for the post-2015 emissions would change the
EPA's conclusion that the NOX substitution used for the RFP
demonstration in the 2017 Eastern Kern Ozone SIP meets the requirements
of CAA section 182(c)(2)(C).
---------------------------------------------------------------------------

    \52\ Eastern Kern 2017 Ozone Plan, Appendix A.
    \53\ CARB Staff Report on Eastern Kern 2017 Ozone Plan, A-8.
    \54\ This is an approximation based on SJV NOX and
VOC emissions in tons per day as shown in the bar chart in CARB
Staff Report on the Eastern Kern 2017 Ozone Plan (see A-8); SJV is
the area most often upwind of Eastern Kern, and its photochemical
modeling includes both areas. The VOC:NOX ratios increase
because NOX declines more than VOC. Specifically the
VOC:NOX ratios for 2010, 2015, and 2020, respectively are
380/400 = 0.95, 315/267 = 1.18, and 300/205 = 1.46, an increasing
sequence that spans the 2012-2020 period. Another estimate can be
made using the SJV emissions from the 2016 SJV Ozone Plan. The
summer tons per day VOC:NOX emissions ratio increases
from 337.3/339.6 = 0.99 in 2012 to 300.2/212.7 = 1.41 in 2020.
---------------------------------------------------------------------------

    Lastly, we note that CAA section 182(c)(2)(C), in contrast to CAA
section 182(c)(2)(A), does not explicitly prescribe the use of
photochemical grid modeling or equivalent analytical method to
demonstrate the equivalence of NOx emission reductions (relative to VOC
emissions reductions) on ozone concentrations. The NOX
equivalence demonstration for RFP purposes need not be based on the
same analytical methods used in the attainment demonstration.
Therefore, we are approving the RFP demonstration and its reliance on
NOX substitution for a portion of the VOC emissions
reductions otherwise required based on both qualitative and
quantitative technical analyses.
    Comment #4: CBD asserts that the EPA fails to give notice of how
the submittal addresses the demonstration required under CAA section
182(c)(2)(C) and thus the EPA's proposal is not in accordance with
procedure required by law. In particular, the commenter states that EPA
has failed to give adequate notice of its proposed interpretation of
section 182(c)(2)(C). The commenter observes that Table 3 of the
proposed rule treats a percentage of NOX reductions as
equivalent to an equal percentage of VOC reductions, but asserts that
the proposed rule does not explain why a percentage reduction in
NOX emissions results in equivalent ozone reductions to an
equal reduction in VOC emissions, as required by section 182(c)(2)(C).
The commenter suggests that the proposed rule may have used the
procedure recommended in a December 1993 guidance document from the
EPA's Office of Air Quality Planning and Standards entitled
``NOX Substitution Guidance.'' The commenter argues that
because the NOX Substitution Guidance is non-binding, the
notice must indicate whether the EPA intends to adopt the Guidance's
interpretation of the CAA, and that if the EPA instead believes that
the Eastern Kern calculation is a legitimate demonstration for other
reasons, it must re-propose the action.
    Response to Comment #4: The EPA disagrees with the commenter that
the proposed rulemaking fails to give adequate notice regarding our
proposed approval of the District's use of NOX substitution,
or that we would be required to re-propose with additional
justification prior to taking final action on this portion of the
proposal. As described in responses to comments #2 and #3 above, the
modeling and analysis submitted to support the District's control
strategy and attainment demonstration highlight the need for
significant NOX reductions in the upwind San Joaquin Valley
and South Coast Air Basin for the Eastern Kern to attain the 2008 ozone
NAAQS, and demonstrate that these NOX reductions will be
more effective on a percentage basis than VOC reductions at reducing
ozone concentrations in the nonattainment area. As described below, our
proposal includes a summary and analysis of relevant portions of the
SIP submittals, including NOX substitution in the RFP
demonstration.
    Section III.C of the proposed rulemaking describes our proposed
approval of the District's RFP

demonstration.\55\ This section describes the statutory and regulatory
requirements for an RFP demonstration, including the option under CAA
section 182(c)(2)(C) to substitute NOX emissions reductions
for VOC reductions, and the reasons for the EPA's approval of this
demonstration. The discussion includes citations to CAA section
182(c)(2)(C) and the implementing regulations for the 2008 ozone NAAQS,
as well as relevant portions of the preamble to the 2008 Ozone SRR that
address the applicable requirements.\56\ The explanation that the
District's RFP demonstration substitutes NOX reductions for
VOC reductions in the RFP demonstration, including the District's
substitution of NOX reductions for VOC reductions on a
percentage basis, is summarized in Table 3 of the proposal.\57\
---------------------------------------------------------------------------

    \55\ 85 FR 68268, 68274-68276.
    \56\ Id. at 68274-68276 (see footnotes 55 and 65).
    \57\ Id. at 68275-68276.
---------------------------------------------------------------------------

    As the commenter notes, the proposed rulemaking does not include a
specific justification in support of the District's use of
NOX substitution on a percentage basis. The discussion and
tables in section III.C of our proposal document the need for
additional NOX reductions exceeding the necessary additional
VOC reductions. As discussed in Response to Comment #2, the EPA finds
that the 2017 Eastern Kern Ozone SIP and additional technical
documentation provide sufficient evidence that NOX emissions
reductions are more effective than VOC reductions on a percentage
basis. This conclusion was based on an analysis of ambient data,
pollution transport patterns, the magnitude of upwind area emissions,
and basic scientific knowledge about the VOC:NOX ratios
downwind of large urban areas. As addressed above, given this need for
NOX reductions and the modeled anticipated impact on Eastern
Kern, substituting NOX for VOC on a percentage-reduction
basis represents a conservative approach that will result in equivalent
or greater reductions in ozone concentrations than would result through
the VOC-only reductions required under CAA section 182(c)(2)(B).
    As the commenter notes, this approach is consistent with the
procedures outlined in the EPA's 1993 NOX Substitution
Guidance. However, as the commenter also notes, the NOX
Substitution Guidance is non-binding, and the EPA must ensure that any
use of NOX substitution is reasonable in light of local
conditions and needs.\58\ In this case, our approval is supported by
the NOX reductions being more effective than VOC in the
area, and the need for NOX reductions as set out in the
control strategies for the upwind SJV and SCAB. For this reason, we
find that the proposed rulemaking and associated supporting documents
included in the docket for that action provide sufficient documentation
that the NOX substitution used in the District's RFP
demonstration is consistent with CAA section 182(c)(2)(C), and we
disagree that the EPA would be required to re-propose with additional
analysis or justification.
---------------------------------------------------------------------------

    \58\ See NOX Substitution Guidance at 3 (noting that
the EPA approves substitution proposals on a case-by-case basis,
including any reasonable substitution proposal).
---------------------------------------------------------------------------

    Comment #5: CBD provides numerous comments directed at the EPA's
NOX Substitution Guidance, contending that if the EPA
intended to adopt the positions set forth in the NOX
Substitution Guidance, the proposal would be arbitrary and capricious
and contrary to law because of problems with the NOX
Substitution Guidance. These comments assert generally that the
NOX Substitution Guidance contradicts CAA section
182(c)(2)(C) by recommending a procedure that fails to demonstrate any
equivalence between VOC and NOX reductions, relies on
incorrect policy assumptions, and gives legal justifications that are
without merit.
    Response to Comment #5: Comments relating solely to the
NOX Substitution Guidance are outside the scope of this
rulemaking action. As noted in our Response to Comment #4 above, our
approval of the District's use of NOX substitution is
supported by local conditions and needs as documented in the modeling
and analysis included in the 2017 Eastern Kern Ozone SIP, and is
consistent with the requirements in CAA section 182(c)(2)(C).
    Comment #6: CBD asserts that, because the EPA must disapprove the
submitted RFP demonstration, the EPA cannot determine that the motor
vehicle emission budgets (MVEBs) are allowable as a portion of the
total allowable emissions to meet RFP, and with no measure of total
allowable emissions for RFP, there is no basis for approval of the
MVEBs.
    Response to Comment #6: As discussed in responses to comments #1
through #4, the EPA concludes that the RFP demonstration can be
approved independently of the attainment demonstration and that the
substitution of NOX emissions reductions for VOC emissions
reductions in the RFP demonstration is adequately supported. In this
final rule, on the basis of the rationale presented in the proposed
rule and in our responses to comments, we are taking final action to
approve the RFP demonstration and related MVEBs.
    Comment #7: CBD contends that the MVEBs must be consistent with
attainment requirements as well as RFP requirements, and in the absence
of an approved attainment demonstration and control strategy, the RFP
MVEBs must be disapproved. In support of this contention, CBD cites
selected portions of CAA section 176(c) and the EPA's transportation
conformity rule. First, under section 176(c)(1)(B)(iii), CBD notes that
a Federal action cannot ``delay timely attainment of any standard,''
and without an approved attainment demonstration and control strategy,
which could require VOC and NOX emissions reductions beyond
those required by section 182(c)(2)(C), there is no way to tell if a
transportation plan, improvement program, or project will ``delay
timely attainment'' of the 2008 ozone standards, even if it stays
within the proposed MVEBs.
    Second, CBD notes that, under the EPA's rules for transportation
conformity, the term ``control strategy implementation plan revision''
is defined as the ``implementation plan which contains specific
strategies for controlling the emissions of and reducing ambient levels
of pollutants in order to satisfy CAA requirements for demonstrations
of reasonable further progress and attainment.'' \59\ For attainment
plans (as opposed to maintenance plans), MVEBs are in part defined as
``that portion of the total allowable emissions defined in the
submitted or approved control strategy implementation plan revision.''
\60\ Thus, CBD argues that the MVEBs depend on the control strategy
implementation plan revision, which must demonstrate both RFP and
attainment.
---------------------------------------------------------------------------

    \59\ 40 CFR 93.101 (emphasis added).
    \60\ Id. (emphasis added).
---------------------------------------------------------------------------

    In addition, CBD notes that the particular MVEBs proposed for
approval are derived from the projected on-road mobile source emissions
estimates in the attainment year (2020) emissions inventory upon which
the attainment demonstration is based, and thus must be consistent with
attainment requirements as well as RFP requirements. Because the EPA
has not approved the attainment demonstration, including the projected
attainment year emissions inventory, CBD argues that the EPA cannot
approve the MVEBs that derive from that inventory.
    Response to Comment #7: First, we acknowledge that the MVEBs are
derived from the projected attainment

year (2020) emissions inventory. However, year 2020 is both an RFP
milestone year and the attainment year for the Eastern Kern Serious
ozone nonattainment area. Therefore, the projected 2020 emissions
inventory is the basis for both the RFP demonstration for that
milestone year and for the attainment demonstration. As explained in
Response to Comment #1, the RFP demonstration and attainment
demonstration requirements are independent requirements under the SRR
and, thus, can be approved separately. In this final action, we are
approving the MVEBs only for RFP purposes and not for attainment
purposes.
    Second, we note that CAA section 176(c)(4)(B) obligates the EPA to
promulgate, and periodically update, criteria and procedures for
demonstrating and assuring conformity in the case of transportation
plans, programs, and projects, and we have done so at 40 CFR part 93,
subpart A (``Conformity to State or Federal Implementation Plans of
Transportation Plans, Programs, and Projects Developed, Funded or
Approved Under Title 23 U.S.C. or the Federal Transit Laws'') (herein,
``transportation conformity rule'').
    Our transportation conformity rule defines ``motor vehicle
emissions budget'' as that portion of the total allowable emissions
defined in the submitted or approved control strategy implementation
plan revision or maintenance plan for a certain date for the purpose of
meeting reasonable further progress milestones or demonstrating
attainment or maintenance of the NAAQS. . . .'' \61\ Further, among the
criteria we must use when evaluating a MVEB for adequacy or approval is
the criterion at 40 CFR 93.118(e)(4)(iv) which requires MVEBs, when
considered together with all other emissions sources, to be consistent
with applicable requirements for reasonable further progress,
attainment, or maintenance (whichever is relevant to the given
implementation plan submission).\62\
---------------------------------------------------------------------------

    \61\ 40 CFR 93.101 (emphasis added).
    \62\ 40 CFR 93.118(e)(4)(iv) (emphases added).
---------------------------------------------------------------------------

    Thus, under our transportation conformity rule, the EPA can approve
MVEBs if we find them consistent, when considered together with all
other emissions sources, with the applicable requirements for RFP or
attainment; it is not required that the MVEBs be consistent with RFP
and attainment but only that they are consistent with the requirement
that is relevant for purposes of the SIP. In this instance, while the
MVEBs for year 2020 are numerically the same for both RFP and
attainment, the relevant requirements are those for RFP, not
attainment, and we are approving the MVEBs as consistent with those
requirements, not the attainment requirements, consistent with the
transportation conformity rule.\63\ This interpretation has been upheld
by the Ninth Circuit in Natural Resources Defense Council v. EPA, 638
F.3d 1183 (9th Cir. 2011). In Natural Resources Defense Council, the
petitioners similarly argued that the Clean Air Act and the EPA's
implementing regulations require the EPA to consider attainment data
when determining the adequacy of budgets for milestone years,\64\ but
the Ninth Circuit agreed with the EPA that the EPA's transportation
conformity rule provides otherwise. More specifically, the court agreed
with the EPA that, for a milestone year, a budget need only demonstrate
reasonable further progress toward the ultimate goal of attainment.\65\
---------------------------------------------------------------------------

    \63\ The commenter claims that the EPA's adequacy determination
is irrelevant for purposes of whether the EPA can approve the MVEBs,
because the EPA has stated that its adequacy review ``should not be
used to prejudge EPA's ultimate approval or disapproval of the
SIP.'' The EPA agrees that the adequacy determination is based on a
cursory review of the SIP submittal when it is made prior to action
on the SIP submittal itself. However, today's adequacy determination
is based on the EPA's complete review, and approval, of the RFP
demonstration in the 2017 Eastern Kern Ozone SIP.
    \64\ Natural Resources Defense Council v. EPA, 638 F.3d 1183,
1191 (9th Cir. 2011).
    \65\ Id.
---------------------------------------------------------------------------

    In light of our responses to the comments and for the reasons given
in the proposed rule, we are taking final action to approve the RFP
demonstration and the related MVEBs and are taking final action to find
the MVEBs adequate for transportation conformity purposes.

III. Final Action

    For the reasons discussed in detail in the proposed rule and
summarized herein, under CAA section 110(k)(3), the EPA is taking final
action to approve as a revision to the California SIP the following
portions of the Eastern Kern 2017 Ozone Plan submitted by CARB on
October 25, 2017, the 2018 SIP Update submitted on December 5, 2018,
and the 2020 Conformity Budget Update submitted on August 31, 2020,
that together comprise the 2017 Eastern Kern Ozone SIP: \66\
---------------------------------------------------------------------------

    \66\ As noted previously, we are deferring action on the
attainment demonstration and reasonably available control measures
demonstration elements of the 2017 Eastern Kern Ozone SIP at this
time.
---------------------------------------------------------------------------

     Base year emissions inventory element in the Eastern Kern
2017 Ozone Plan as meeting the requirements of CAA sections 172(c)(3)
and 182(a)(1) and 40 CFR 51.1115 for the 2008 ozone NAAQS;
     Emissions statement element in the Eastern Kern 2017 Ozone
Plan as meeting the requirements of CAA section 182(a)(3)(B) and 40 CFR
51.1102 for the 2008 ozone NAAQS;
     ROP demonstration element in the Eastern Kern 2017 Ozone
Plan as meeting the requirements of CAA 182(b)(1) and 40 CFR
51.1110(a)(2) for the 2008 ozone NAAQS;
     RFP demonstration element in the 2018 SIP Update as
meeting the requirements of CAA sections 172(c)(2) and 182(c)(2)(B),
and 40 CFR 51.1110(a)(2)(ii) for the 2008 ozone NAAQS;
     Motor vehicle emissions budgets in the 2020 Conformity
Budget Update for the 2020 RFP milestone year, as shown below, because
they are consistent with the RFP demonstration for the 2008 ozone NAAQS
finalized for approval herein and meet the other criteria in 40 CFR
93.118(e);

  Transportation Conformity Budgets for the 2008 Ozone NAAQS in Eastern
                                  Kern
                    [Summer planning inventory, tpd]
------------------------------------------------------------------------
                 Budget year                       VOC           NOX
------------------------------------------------------------------------
2020........................................          1.3           3.6
------------------------------------------------------------------------

    We are also taking final action to find that:
     The enhanced monitoring requirements of CAA section
182(c)(1) and 40 CFR 51.1102 are being met in Eastern Kern for the 2008
ozone NAAQS; \67\ and
---------------------------------------------------------------------------

    \67\ Regarding the Serious nonattainment area requirements for
new source review (NSR) and for implementation of reasonably
available control technology (RACT) for the 2008 ozone NAAQS in
Eastern Kern, we will be taking action as necessary on district
rules addressing the NSR and RACT requirements in separate
rulemakings and will evaluate compliance with the applicable Serious
area nonattainment requirements at that time.
---------------------------------------------------------------------------

     The submitted 2020 budgets included in the 2020 Conformity
Budget Update are adequate for transportation conformity purposes.\68\
---------------------------------------------------------------------------

    \68\ Pursuant to 40 CFR 93.118(f)(2)(iii), the EPA's adequacy
determination is effective upon publication of this final rule in
the Federal Register. Upon the effective date of the adequacy
determination, the 2020 budgets from the in the 2020 Conformity
Budget Update will replace the budgets that were previously found
adequate for use in transportation conformity determinations (i.e.,
the 2008 budgets from the ``Eastern Kern County 2008 8-hour Ozone
Early Progress Plan.''
---------------------------------------------------------------------------

    Lastly, we are approving conditionally, under CAA section
110(k)(4), the contingency measure

element of the 2017 Eastern Kern Ozone SIP as meeting the requirements
of CAA sections 172(c)(9) and 182(c)(9) for RFP and attainment
contingency measures. Our approval is based on commitments by the
District and CARB to supplement the element through submission, as a
SIP revision (within one year of our final conditional approval
action), of a revised District rule or rules that would add new limits
or other requirements if an RFP milestone is not met or if Eastern Kern
fails to attain the 2008 ozone NAAQS by the applicable attainment
date.\69\
---------------------------------------------------------------------------

    \69\ Letter dated September 1, 2020, from Glen E. Stephens, Air
Pollution Control Officer, EKAPCD, to Richard Corey, Executive
Officer, CARB; and letter dated September 18, 2020, from Richard W.
Corey, Executive Officer, CARB, to John Busterud, Regional
Administrator, EPA Region IX.
---------------------------------------------------------------------------

IV. 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 approve state
choices, provided that they meet the criteria of the Clean Air Act.
Accordingly, this action merely approves or conditionally approves
state plans 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 13563 (76 FR 3821, January 21,
2011);
     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 an economically significant regulatory action based
on health or safety risks subject to Executive Order 13045 (62 FR
19885, April 23, 1997);
     Is not a significant regulatory action subject to
Executive Order 13211 (66 FR 28355, May 22, 2001);
     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; and
     Does not provide the EPA with the discretionary authority
to address disproportionate human health or environmental effects with
practical, appropriate, and legally permissible methods under Executive
Order 12898 (59 FR 7629, February 16, 1994).
    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).
    The Congressional Review Act, 5 U.S.C. 801 et seq., as added by the
Small Business Regulatory Enforcement Fairness Act of 1996, generally
provides that before a rule may take effect, the agency promulgating
the rule must submit a rule report, which includes a copy of the rule,
to each House of the Congress and to the Comptroller General of the
United States. The EPA will submit a report containing this action and
other required information to the U.S. Senate, the U.S. House of
Representatives, and the Comptroller General of the United States prior
to publication of the rule in the Federal Register. A major rule cannot
take effect until 60 days after it is published in the Federal
Register. 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 August 24, 2021. 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, Intergovernmental relations, Nitrogen dioxide, Ozone,
Reporting and recordkeeping requirements, Volatile organic compounds.

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

    Dated: June 16, 2021.
Deborah Jordan,
Acting Regional Administrator, Region IX.

    For the reasons stated in the preamble, the EPA amends Part 52,
chapter I, title 40 of the Code of Federal Regulations 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 reserving paragraphs (c)(556), (557),
(558), and (559), and adding paragraphs (c)(514)(ii)(A)(8), (c)(560)
and (c)(561) to read as follows:

Sec.  52.220  Identification of plan--in part.

* * * * *
    (c) * * *
    (514) * * *
    (ii) * * *
    (A) * * *
    (8) 2018 Updates to the California State Implementation Plan,
adopted on October 25, 2018, chapter IV (``SIP Elements for Eastern
Kern County''); and pages A-11 through A-14 of appendix A
(``Nonattainment Area Inventories''), only.
* * * * *
    (560) The following plan was submitted on October 25, 2017 by the
Governor's designee.
    (i) [Reserved]
    (ii) Additional materials.
    (A) Eastern Kern Air Pollution Control District.
    (1) 2017 Ozone Attainment Plan For 2008 Federal 75 ppb 8-Hour Ozone
Standard, adopted on July 27, 2017, excluding chapter XI (``Reasonably
Available Control Measures Demonstration'') and chapter XIII
(``Attainment Demonstration'').
    (2) [Reserved]
    (B) [Reserved]
    (561) The following plan was submitted on August 31, 2020 by the
Governor's designee as an attachment to a letter dated August 25, 2020.
    (i) [Reserved]
    (ii) Additional materials.
    (A) California Air Resources Board.
    (1) Transportation Conformity Budget State Implementation Plan
Update for

the Eastern Kern 2017 Ozone Attainment Plan, release date: June 19,
2020.
    (2) [Reserved]
    (B) [Reserved]
* * * * *

0
3. Section 52.248 is amended by adding paragraph (m) to read as
follows:

Sec.  52.248  Identification of plan--conditional approval.

* * * * *
    (m) The EPA is conditionally approving the California State
Implementation Plan (SIP) for Eastern Kern for the 2008 ozone NAAQS
with respect to the contingency measures requirements of CAA sections
172(c)(9) and 182(c)(9). The conditional approval is based on a
commitment from the Eastern Kern Air Pollution Control District
(District) in a letter dated September 1, 2020, to adopt a specific
rule revision or revisions, and a commitment from the California Air
Resources Board (CARB) dated September 18, 2020, to submit the amended
District rule or rules to the EPA within 12 months of the final
conditional approval. If the District or CARB fail to meet their
commitments within one year of the final conditional approval, the
conditional approval is treated as a disapproval.

[FR Doc. 2021-13608 Filed 6-24-21; 8:45 am]
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