[Federal Register Volume 86, Number 120 (Friday, June 25, 2021)]
[Rules and Regulations]
[Pages 33528-33539]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[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

[[Page 33529]]

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 protected].

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

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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

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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

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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.

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[[Page 33533]]

    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

[[Page 33534]]

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

[[Page 33535]]

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

[[Page 33536]]

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

[[Page 33537]]

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

[[Page 33538]]

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

[[Page 33539]]

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]
BILLING CODE 6560-50-P