[Federal Register Volume 87, Number 100 (Tuesday, May 24, 2022)]
[Proposed Rules]
[Pages 31443-31462]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2022-11150]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 52
[EPA-R09-OAR-2022-0394; EPA-HQ-OAR-2021-0663; FRL-9772-01-R9]
Air Plan Disapproval; California; Interstate Transport of Air
Pollution for the 2015 8-Hour Ozone National Ambient Air Quality
Standards
AGENCY: Environmental Protection Agency (EPA).
ACTION: Proposed rule.
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SUMMARY: Pursuant to the Clean Air Act (CAA or the ``Act''), the
Environmental Protection Agency (EPA) is proposing to disapprove a
State Implementation Plan (SIP) submittal from California addressing
interstate transport for the 2015 8-hour ozone national ambient air
quality standards (NAAQS). The ``good neighbor'' or ``interstate
transport'' provision of the Act requires that each state's SIP contain
adequate provisions to prohibit emissions from within the state from
significantly contributing to nonattainment or interfering with
maintenance of the NAAQS in other states. This requirement is part of
the broader set of ``infrastructure'' requirements, which are designed
to ensure that the structural components of each state's air quality
management program are adequate to meet the state's responsibilities
under the CAA. This disapproval, if finalized, will establish a 2-year
deadline for the EPA to promulgate a Federal Implementation Plan (FIP)
to address the relevant interstate transport requirements, unless the
EPA approves a subsequent SIP submittal that meets these requirements.
Disapproval does not start a mandatory sanctions clock.
DATES:
Comments: Written comments must be received on or before July 25,
2022.
ADDRESSES: You may send comments, identified as Docket No. EPA-R09-OAR-
2022-0394, by any of the following methods: Federal eRulemaking Portal
at https://www.regulations.gov following the online instructions for
submitting comments or via email to [email protected]. Include
Docket ID No. EPA-R09-OAR-2022-0394 in the subject line of the message.
Instructions: All submissions received must include the Docket ID
No. for this rulemaking. Comments received may be posted without change
to https://www.regulations.gov, including any personal information
provided. For detailed instructions on sending comments and additional
information on the rulemaking process, see the ``Public Participation''
heading of the SUPPLEMENTARY INFORMATION section of this document.
FOR FURTHER INFORMATION CONTACT: Tom Kelly, EPA Region IX, 75 Hawthorne
St., San Francisco, CA 94105. By phone: 415-972-3856 or by email at
[email protected].
SUPPLEMENTARY INFORMATION:
Public Participation: Submit your comments, identified by Docket ID
No. EPA-R09-OAR-2022-0394, at https://www.regulations.gov (our
preferred method), or the other methods identified in the ADDRESSES
section. Once submitted, comments cannot be edited or removed from the
docket. The EPA may publish any comment received to its public docket.
Do not submit to EPA's docket at https://www.regulations.gov any
information
[[Page 31444]]
you consider to be Confidential Business Information (CBI) or other
information whose disclosure is restricted by statute. Multimedia
submissions (audio, video, etc.) must be accompanied by a written
comment. The written comment is considered the official comment and
should include discussion of all points you wish to make. The EPA will
generally not consider comments or comment contents located outside of
the primary submission (i.e., on the web, cloud, or other file sharing
system).
There are two dockets supporting this action, EPA-R09-OAR-2022-0394
and EPA-HQ-OAR-2021-0663. Docket No. EPA-R09-OAR-2022-0394 contains
information specific to California, including the notice of proposed
rulemaking. Docket No. EPA-HQ-OAR-2021-0663 contains additional
modeling files, emissions inventory files, technical support documents,
and other relevant supporting documentation regarding interstate
transport of emissions for the 2015 8-hour ozone NAAQS that are being
used to support this action. All comments regarding information in
either of these dockets are to be made in Docket No. EPA-R09-OAR-2022-
0394. For additional submission methods, 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
Tom Kelly, (415) 972-3856, [email protected]. For the full EPA
public comment policy, information about CBI or multimedia submissions,
and general guidance on making effective comments, please visit https://www.epa.gov/dockets/commenting-epa-dockets.
The index to the docket for this action, Docket No. EPA-R09-OAR-
2022-0394, is available electronically at www.regulations.gov. While
all documents in the docket are listed in the index, some information
may not be publicly available due to docket file size restrictions or
content (e.g., CBI).
Throughout this document, ``we,'' ``us,'' and ``our'' means the
EPA.
Table of Contents
I. Background
A. Description of Statutory Background
B. Description of the EPA's Four Step Interstate Transport
Regulatory Process
C. Background on the EPA's Ozone Transport Modeling Information
D. The EPA's Approach To Evaluating Interstate Transport SIPs
for the 2015 8-Hour Ozone NAAQS
II. SIP Submission Addressing Interstate Transport of Air Pollution
for the 2015 8-Hour Ozone NAAQS
A. Information Provided at Steps 1 and 2
B. Information Provided at Step 3
C. Information Provided at Step 4
III. EPA Evaluation
A. Evaluation of California Weight of Evidence Analysis
B. Evaluation of Information Provided by California Regarding
Step 1 and 2
C. Results of the EPA's Step 1 and Step 2 Modeling and Findings
for California
D. Evaluation of Information Provided Regarding Step 3
E. Evaluation of Information Provided Regarding Step 4
F. Tribal Consultation
G. Conclusion
IV. Proposed Action
V. Statutory and Executive Order Reviews
I. Background
A. Description of Statutory Background
On October 1, 2015, the EPA promulgated a revision to the ozone
NAAQS (``2015 8-hour ozone NAAQS''), lowering the level of both the
primary and secondary standards to 0.070 parts per million (ppm).\1\
Section 110(a)(1) of the CAA requires states to submit, within 3 years
after promulgation of a new or revised standard, SIP submissions
meeting the applicable requirements of section 110(a)(2).\2\ One of
these applicable requirements is found in CAA section
110(a)(2)(D)(i)(I), otherwise known as the ``interstate transport'' or
``good neighbor'' provision, which generally requires SIPs to contain
adequate provisions to prohibit in-state emissions activities from
having certain adverse air quality effects on other states due to
interstate transport of pollution. There are two so-called ``prongs''
within CAA section 110(a)(2)(D)(i)(I). An interstate SIP submission for
a new or revised NAAQS must contain adequate provisions prohibiting any
source or other type of emissions activity within the state from
emitting air pollutants in amounts that will significantly contribute
to nonattainment of the NAAQS in another state (prong 1) or interfere
with maintenance of the NAAQS in another state (prong 2). The EPA and
states must give independent significance to prong 1 and prong 2 when
evaluating downwind air quality problems under CAA section
110(a)(2)(D)(i)(I).\3\
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\1\ National Ambient Air Quality Standards for Ozone, Final
Rule, 80 FR 65292 (October 26, 2015). Although the level of the
standard is specified in the units of ppm, ozone concentrations are
also described in parts per billion (ppb). For example, 0.070 ppm is
equivalent to 70 ppb.
\2\ SIP revisions that are intended to meet the applicable
requirements of section 110(a)(1) and (2) of the CAA are often
referred to as infrastructure SIPs and the applicable elements under
section 110(a)(2) are referred to as infrastructure requirements.
\3\ See North Carolina v. EPA, 531 F.3d 896, 909-11 (DC Cir.
2008).
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B. Description of the EPA's Four Step Interstate Transport Regulatory
Process
The EPA is using the 4-step interstate transport framework (or 4-
step framework) to evaluate the state's SIP submittal addressing the
interstate transport provision for the 2015 8-hour ozone NAAQS. The EPA
has addressed the interstate transport requirements of CAA section
110(a)(2)(D)(i)(I) with respect to prior ozone NAAQS in several
regional regulatory actions, including the Cross-State Air Pollution
Rule (CSAPR), which addressed interstate transport with respect to the
1997 ozone NAAQS as well as the 1997 and 2006 fine particulate matter
standards,\4\ and the Cross-State Air Pollution Rule Update (CSAPR
Update) \5\ and the Revised CSAPR Update, both of which addressed the
2008 ozone NAAQS.\6\ Through the development and implementation of the
CSAPR rulemakings and prior regional rulemakings pursuant to the
interstate transport provision,\7\ the EPA, working in partnership with
states, developed the following 4-step framework to evaluate a State's
obligations to eliminate interstate transport emissions under the
interstate transport provision for the ozone NAAQS: (1) Identify
monitoring sites that are projected to have problems attaining and/or
maintaining the NAAQS (i.e., nonattainment and/or maintenance
receptors); (2) identify states that impact those air quality problems
in other (i.e., downwind) states sufficiently such that the states are
considered ``linked'' and therefore warrant further review and
analysis; (3) identify the emissions reductions necessary (if any),
applying a multifactor analysis, to eliminate each linked upwind
state's significant contribution to nonattainment or interference with
maintenance of the
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NAAQS at the locations identified in Step 1; and (4) adopt permanent
and enforceable measures needed to achieve those emissions reductions.
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\4\ See Federal Implementation Plans: Interstate Transport of
Fine Particulate Matter and Ozone and Correction of SIP Approvals,
76 FR 48208 (Aug. 8, 2011).
\5\ Cross-State Air Pollution Rule Update for the 2008 Ozone
NAAQS, 81 FR 74504 (Oct. 26, 2016).
\6\ In 2019, the D.C. Circuit Court of Appeals remanded the
CSAPR Update to the extent it failed to require upwind states to
eliminate their significant contribution by the next applicable
attainment date by which downwind states must come into compliance
with the NAAQS, as established under CAA section 181(a). Wisconsin
v. EPA, 938 F.3d 303, 313 (DC Cir. 2019). The Revised CSAPR Update
for the 2008 Ozone NAAQS, 86 FR 23054 (April 30, 2021), responded to
the remand of the CSAPR Update in Wisconsin and the vacatur of a
separate rule, the ``CSAPR Close-Out,'' 83 FR 65878 (December 21,
2018), in New York v. EPA, 781 F. App'x. 4 (DC Cir. 2019).
\7\ In addition to the CSAPR rulemakings, other regional
rulemakings addressing ozone transport include the ``NOX
SIP Call,'' 63 FR 57356 (October 27, 1998), and the ``Clean Air
Interstate Rule'' (CAIR), 70 FR 25162 (May 12, 2005).
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C. Background on the EPA's Ozone Transport Modeling Information
The EPA has performed nationwide air quality modeling to project
ozone design values that are used in combination with measured data to
identify nonattainment and maintenance receptors. To quantify the
contribution of emissions from specific upwind states to 2023 ozone
design values for the identified downwind nonattainment and maintenance
receptors, the EPA performed nationwide, state-level ozone source
apportionment modeling. The source apportionment modeling provided
contributions to ozone at receptors from precursor emissions of
anthropogenic nitrogen oxides (NOX) and volatile organic
compounds (VOCs) in individual states and other sources.\8\
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\8\ More information on the source apportionment modeling can be
found in the Air Quality Modeling Technical Support Document for the
2015 Ozone NAAQS Transport SIP Proposed Actions.
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The EPA has released several documents containing projected ozone
design values, contributions, and information relevant to evaluating
interstate transport with respect to the 2015 8-hour ozone NAAQS.
First, on January 6, 2017, the EPA published a notice of data
availability (NODA) in which we requested comment on preliminary
interstate ozone transport data including projected ozone design values
and interstate contributions for 2023 using a 2011 base year
platform.\9\ In the NODA, the EPA used the year 2023 as the analytic
year for this preliminary modeling because that year aligns with the
expected attainment year for ``Moderate'' ozone nonattainment areas for
the 2015 8-hour ozone NAAQS.\10\ On October 27, 2017, we released a
memorandum using the ``en'' emissions inventory (``October 2017
memorandum'') containing updated modeling data for 2023, which
incorporated changes made in response to comments on the NODA, and
noted that the modeling may be useful for states developing SIPs to
address interstate transport obligations for the 2008 ozone NAAQS.\11\
On March 27, 2018, we issued a memorandum (``March 2018 memorandum'')
noting that the same 2023 modeling data released in the October 2017
memorandum could also be useful for identifying potential downwind air
quality problems with respect to the 2015 8-hour ozone NAAQS at Step 1
of the 4-step interstate transport framework.\12\ The March 2018
memorandum also included the then newly available contribution modeling
data for 2023 to assist states in evaluating their impact on potential
downwind air quality problems for the 2015 8-hour ozone NAAQS under
Step 2 of the 4-step interstate transport framework.\13\ The EPA
subsequently issued two more memoranda in August and October 2018,
providing additional information to states developing interstate
transport SIP submissions for the 2015 8-hour ozone NAAQS concerning,
respectively, potential contribution thresholds that may be appropriate
to apply in Step 2 of the 4-step interstate transport framework, and
considerations for identifying downwind areas that may have problems
maintaining the standard at Step 1 of the 4-step interstate transport
framework.\14\
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\9\ See Notice of Availability of the Environmental Protection
Agency's Preliminary Interstate Ozone Transport Modeling Data for
the 2015 8-hour Ozone National Ambient Air Quality Standard (NAAQS),
82 FR 1733 (January 6, 2017).
\10\ 82 FR 1733, 1735.
\11\ See Information on the Interstate Transport State
Implementation Plan Submissions for the 2008 Ozone National Ambient
Air Quality Standards under Clean Air Act Section
110(a)(2)(D)(i)(I), October 27, 2017, available in docket ID No.
EPA-HQ-OAR-2021-0663.
\12\ See Information on the Interstate Transport State
Implementation Plan Submissions for the 2015 Ozone National Ambient
Air Quality Standards under Clean Air Act Section
110(a)(2)(D)(i)(I), March 27, 2018 (``March 2018 memorandum''),
available in docket ID No. EPA-HQ-OAR-2021-0663.
\13\ The March 2018 memorandum, however, provided, ``While the
information in this memorandum and the associated air quality
analysis data could be used to inform the development of these SIPs,
the information is not a final determination regarding states'
obligations under the good neighbor provision. Any such
determination would be made through notice-and-comment rulemaking.''
\14\ See Analysis of Contribution Thresholds for Use in Clean
Air Act Section 110(a)(2)(D)(i)(I) Interstate Transport State
Implementation Plan Submissions for the 2015 Ozone National Ambient
Air Quality Standards, August 31, 2018 (``August 2018 memorandum''),
and Considerations for Identifying Maintenance Receptors for Use in
Clean Air Act Section 110(a)(2)(D)(i)(I) Interstate Transport State
Implementation Plan Submissions for the 2015 Ozone National Ambient
Air Quality Standards, October 19, 2018 (``October 2018
memorandum''), available in docket ID No. EPA-HQ-OAR-2021-0663.
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Since the release of the modeling data shared in the March 2018
memorandum, the EPA performed updated modeling using a 2016-based
emissions modeling platform (i.e., 2016v1). This emissions platform was
developed under the EPA/Multi-Jurisdictional Organization (MJO)/state
collaborative project.\15\ This collaborative project was a multi-year
joint effort by the EPA, MJOs, and states to develop a new, more recent
emissions platform for use by the EPA and states in regulatory modeling
as an improvement over the dated 2011-based platform that the EPA had
used to project ozone design values and contribution data provided in
the 2017 and 2018 memoranda. The EPA used the 2016v1 emissions to
project ozone design values and contributions for 2023. On October 30,
2020, in the notice of proposed rulemaking for the Revised CSAPR
Update, the EPA released and accepted public comment on 2023 modeling
that used the 2016v1 emissions platform.\16\ Although the Revised CSPAR
Update addressed transport for the 2008 ozone NAAQS, the projected
design values and contributions from the 2016v1 platform are also
useful for identifying downwind ozone problems and linkages with
respect to the 2015 ozone NAAQS.\17\
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\15\ The results of this modeling, as well as the underlying
modeling files, are included in docket ID No. EPA-HQ-OAR-2021-0663.
\16\ See 85 FR 68964, 68981.
\17\ See the Air Quality Modeling Technical Support Document for
the Final Revised Cross-State Air Pollution Rule Update, included in
the Headquarters docket ID No. EPA-HQ-OAR-2021-0663.
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Following the final Revised CSAPR Update, the EPA made further
updates to the 2016 emissions platform to include mobile emissions from
the EPA's Motor Vehicle Emission Simulator MOVES3 model \18\ and
updated emissions projections for electric generating units (EGUs) that
reflect the emissions reductions from the Revised CSAPR Update, recent
information on plant closures, and other sector trends. The construct
of the updated emissions platform, 2016v2, is described in the
emissions modeling technical support document (TSD) for this proposed
rule.\19\ The EPA performed air quality modeling of the 2016v2
emissions using the most recent public release version of the
Comprehensive Air-quality Model with extensions (CAMx) photochemical
modeling, version 7.10.\20\ The EPA now proposes to primarily rely on
modeling based on the updated and newly
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available 2016v2 emissions platform in evaluating these submissions
with respect to Steps 1 and 2 of the 4-step interstate transport
framework and generally referenced within this action as 2016v2
modeling for 2023. By using the updated modeling results, the EPA is
using the most current and technically appropriate information for this
proposed rulemaking. Section III.C. of this notice and the Air Quality
Modeling TSD for 2015 Ozone NAAQS Transport SIP Proposed Actions,
included in Docket ID No. EPA-HQ-OAR-2021-0663 for this proposal,
contain additional detail on the EPA's 2016v2 modeling. In this notice,
the EPA is accepting public comment on this updated 2023 modeling,
which uses the 2016v2 emissions platform. Comments on the EPA's air
quality modeling should be submitted in the Regional docket for this
action, docket ID No. EPA-R09-OAR-2022-0394. Comments are not being
accepted in docket ID No. EPA-HQ-OAR-2021-0663.
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\18\ Additional details and documentation related to the MOVES3
model can be found at https://www.epa.gov/moves/latest-version-motor-vehicle-emission-simulator-moves.
\19\ See Technical Support Document (TSD) Preparation of
Emissions Inventories for the 2016v2 North American Emissions
Modeling Platform included in the Headquarters docket ID No. EPA-HQ-
OAR-2021-0663.
\20\ Ramboll Environment and Health, January 2021, www.camx.com.
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States may have chosen to rely on the results of EPA modeling and/
or alternative modeling performed by states or MJOs to evaluate
downwind air quality problems and contributions as part of their
submissions. In Section III.A. and III.B. we evaluate how California
used air quality modeling information in their submission.
D. The EPA's Approach To Evaluating Interstate Transport SIPs for the
2015 8-Hour Ozone NAAQS
The EPA proposes to apply a consistent set of policy judgments
across all states for purposes of evaluating interstate transport
obligations and the approvability of interstate transport SIP
submittals for the 2015 8-hour ozone NAAQS. These policy judgments
reflect consistency with relevant case law and past agency practice as
reflected in the CSAPR and related rulemakings. Nationwide consistency
in approach is particularly important in the context of interstate
ozone transport, which is a regional-scale pollution problem involving
many smaller contributors. Effective policy solutions to the problem of
interstate ozone transport going back to the NOX SIP Call
have necessitated the application of a uniform framework of policy
judgments in order to ensure an ``efficient and equitable'' approach.
See EME Homer City Generation, LP v. EPA, 572 U.S. 489, 519 (2014).
In the March, August, and October 2018 memoranda, the EPA
recognized that states may be able to establish alternative approaches
to addressing their interstate transport obligations for the 2015 8-
hour ozone NAAQS that vary from a nationally uniform framework. The EPA
emphasized in these memoranda, however, that such alternative
approaches must be technically justified and appropriate in light of
the facts and circumstances of each particular state's submittal. In
general, the EPA continues to believe that deviation from a nationally
consistent approach to ozone transport must be substantially justified
and have a well-documented technical basis that is consistent with
relevant case law. Where states submitted SIPs that rely on any such
potential ``flexibilities'' as may have been identified or suggested in
the past, the EPA will evaluate whether the state adequately justified
the technical and legal basis for doing so.
The EPA notes that certain concepts included in an attachment to
the March 2018 memorandum require unique consideration, and these ideas
do not constitute agency guidance with respect to transport obligations
for the 2015 ozone NAAQS. Attachment A to the March 2018 memorandum
identified a ``Preliminary List of Potential Flexibilities'' that could
potentially inform SIP development.\21\ However, the EPA made clear in
that Attachment that the list of ideas were not suggestions endorsed by
the Agency but rather ``comments provided in various forums'' on which
the EPA sought ``feedback from interested stakeholders.'' \22\ Further,
Attachment A stated, ``EPA is not at this time making any determination
that the ideas discussed below are consistent with the requirements of
the CAA, nor are we specifically recommending that states use these
approaches.'' \23\ Attachment A to the March 2018 memorandum,
therefore, does not constitute agency guidance, but was intended to
generate further discussion around potential approaches to addressing
ozone transport among interested stakeholders. To the extent states
sought to develop or rely on these ideas in support of their SIP
submittals, the EPA will thoroughly review the technical and legal
justifications for doing so.
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\21\ March 2018 memorandum, Attachment A.
\22\ Id. at A-1.
\23\ Id.
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The remainder of this section describes the EPA's proposed
framework with respect to analytic year, definition of nonattainment
and maintenance receptors, selection of contribution threshold, and
multifactor control strategy assessment.
1. Selection of Analytic Year
In general, the states and the EPA must implement the interstate
transport provision in a manner ``consistent with the provisions of
[title I of the CAA.]'' CAA section 110(a)(2)(D)(i). This requires,
among other things, that these obligations are addressed consistently
with the timeframes for downwind areas to meet their CAA obligations.
With respect to ozone NAAQS, under CAA section 181(a), this means
obligations must be addressed ``as expeditiously as practicable'' and
no later than the schedule of attainment dates provided in CAA section
181(a)(1).\24\ Several D.C. Circuit court decisions address the issue
of the relevant analytic year for the purposes of evaluating ozone
transport air quality problems. On September 13, 2019, the D.C. Circuit
issued a decision in Wisconsin v. EPA, remanding the CSAPR Update to
the extent that it failed to require upwind states to eliminate their
significant contribution by the next applicable attainment date by
which downwind states must come into compliance with the NAAQS, as
established under CAA section 181(a). 938 F.3d at 313.
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\24\ For attainment dates for the 2015 8-hour ozone NAAQS, refer
to CAA section 181(a), 40 CFR 51.1303, and Additional Air Quality
Designations for the 2015 Ozone National Ambient Air Quality
Standards, 83 FR 25776 (June 4, 2018, effective August 3, 2018).
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On May 19, 2020, the D.C. Circuit issued a decision in Maryland v.
EPA that cited the Wisconsin decision in holding that the EPA must
assess the impact of interstate transport on air quality at the next
downwind attainment date, including ``Marginal'' area attainment dates,
in evaluating the basis for the EPA's denial of a petition under CAA
section 126(b). Maryland v. EPA, 958 F.3d 1185, 1203-04 (D.C. Cir.
2020). The court noted that ``section 126(b) incorporates the Good
Neighbor Provision,'' and, therefore, ``EPA must find a violation [of
section 126] if an upwind source will significantly contribute to
downwind nonattainment at the next downwind attainment deadline.
Therefore, the agency must evaluate downwind air quality at that
deadline, not at some later date.'' Id. at 1204 (emphasis added). The
EPA interprets the court's holding in Maryland as requiring the states
and the Agency, under the good neighbor provision, to assess downwind
air quality as expeditiously as practicable and no later than the next
applicable attainment date,\25\ which is now the
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Moderate area attainment date under CAA section 181 for ozone
nonattainment. The Moderate area attainment date for the 2015 8-hour
ozone NAAQS is August 3, 2024.\26\ The EPA believes that 2023 is now
the appropriate year for analysis of interstate transport obligations
for the 2015 8-hour ozone NAAQS, because the 2023 ozone season is the
last relevant ozone season during which achieved emissions reductions
in linked upwind states could assist downwind states with meeting the
August 3, 2024 Moderate area attainment date for the 2015 8-hour ozone
NAAQS.
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\25\ We note that the court in Maryland did not have occasion to
evaluate circumstances in which the EPA may determine that an upwind
linkage to a downwind air quality problem exists at steps 1 and 2 of
the interstate transport framework by a particular attainment date,
but for reasons of impossibility or profound uncertainty the Agency
is unable to mandate upwind pollution controls by that date. See
Wisconsin, 938 F.3d at 320. The D.C. Circuit noted in Wisconsin that
upon a sufficient showing, these circumstances may warrant
flexibility in effectuating the purpose of the interstate transport
provision.
\26\ See CAA section 181(a); 40 CFR 51.1303; Additional Air
Quality Designations for the 2015 Ozone National Ambient Air Quality
Standards, 83 FR 25776 (June 4, 2018, effective Aug. 3, 2018).
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The EPA recognizes that the attainment date for nonattainment areas
classified as Marginal for the 2015 8-hour ozone NAAQS was August 3,
2021. Under the Maryland holding, any necessary emissions reductions to
satisfy interstate transport obligations should have been implemented
by no later than this date. At the time of the statutory deadline to
submit interstate transport SIPs (October 1, 2018), many states relied
upon the EPA modeling of the year 2023, and no state provided an
alternative analysis using a 2021 analytic year (or the prior 2020
ozone season). However, the EPA must act on SIP submittals using the
information available at the time it takes such action. In this
circumstance, the EPA does not believe it would be appropriate to
evaluate states' obligations under CAA section 110(a)(2)(D)(i)(I) as of
an attainment date that is wholly in the past, because the Agency
interprets the interstate transport provision as forward looking. See
86 FR at 23054, 23074; see also Wisconsin, 938 F.3d at 322.
Consequently, in this proposal the EPA will use the analytical year of
2023 to evaluate each state's CAA section 110(a)(2)(D)(i)(I) SIP
submission with respect to the 2015 8-hour ozone NAAQS.
2. Step 1 of the 4-Step Interstate Transport Framework
In Step 1, the EPA identifies monitoring sites that are projected
to have problems attaining and/or maintaining the NAAQS in the 2023
analytic year. Where the EPA's analysis shows that a site does not fall
under the definition of a nonattainment or maintenance receptor, that
site is excluded from further analysis under the EPA's 4-step
interstate transport framework. For sites that are identified as a
nonattainment or maintenance receptor in 2023, we proceed to the next
step of our 4-step interstate transport framework by identifying the
upwind state's contribution to those receptors.
The EPA's approach to identifying ozone nonattainment and
maintenance receptors in this action is consistent with the approach
used in previous transport rulemakings. The EPA's approach gives
independent consideration to both the ``contribute significantly to
nonattainment'' and the ``interfere with maintenance'' prongs of CAA
section 110(a)(2)(D)(i)(I), consistent with the D.C. Circuit's
direction in North Carolina v. EPA.\27\
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\27\ See North Carolina v. EPA, 531 F.3d at 910-11 (holding that
the EPA must give ``independent significance'' to each prong of CAA
section 110(a)(2)(D)(i)(I)).
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For the purpose of this proposal, the EPA identifies nonattainment
receptors as those monitoring sites that are projected to have average
design values that exceed the NAAQS and that are also measuring
nonattainment based on the most recent monitored design values. This
approach is consistent with prior transport rulemakings, such as the
CSAPR Update, where the EPA defined nonattainment receptors as those
areas that both currently measure nonattainment and that the EPA
projects will be in nonattainment in the future analytic year (i.e.,
2023).\28\
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\28\ See 81 FR 74504 (October 26, 2016). This same concept,
relying on both current monitoring data and modeling to define
nonattainment receptors, was also applied in CAIR. See 70 FR 25162,
25241 and 25249 (January 14, 2005); see also North Carolina, 531
F.3d at 913-14 (affirming as reasonable EPA's approach to defining
nonattainment in CAIR).
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In addition, in this proposal, the EPA identifies a receptor to be
a ``maintenance'' receptor for purposes of defining interference with
maintenance, consistent with the method used in the CSAPR and upheld by
the D.C. Circuit in EME Homer City Generation, L.P. v. EPA, 795 F.3d
118, 136 (D.C. Cir. 2015).\29\ Specifically, the EPA identified
maintenance receptors as those receptors that would have difficulty
maintaining the relevant NAAQS in a scenario that takes into account
historical variability in air quality at that receptor. The variability
in air quality was determined by evaluating the ``maximum'' future
design value at each receptor based on a projection of the maximum
measured design value over the relevant base period. The EPA interprets
the projected maximum future design value to be a potential future air
quality outcome consistent with the meteorology that yielded maximum
measured concentrations in the ambient data set analyzed for that
receptor (i.e., ozone conducive meteorology). The EPA also recognizes
that previously experienced meteorological conditions (e.g., dominant
wind direction, temperatures, vertical mixing, insolation, and air mass
patterns) promoting ozone formation that led to maximum concentrations
in the measured data may reoccur in the future. The maximum design
value gives a reasonable projection of future air quality at the
receptor under a scenario in which such conditions do, in fact,
reoccur. The projected maximum design value is used to identify upwind
emissions that, under those circumstances, could interfere with the
downwind area's ability to maintain the NAAQS.
---------------------------------------------------------------------------
\29\ See 76 FR 48208 (August 8, 2011). CSAPR Update and Revised
CSAPR Update also used this approach. See 81 FR 74504 (October 26,
2016) and 86 FR 23054 (April 30, 2021).
---------------------------------------------------------------------------
Recognizing that nonattainment receptors are also, by definition,
maintenance receptors, the EPA often uses the term ``maintenance-only''
to refer to those receptors that are not nonattainment receptors.
Consistent with the concepts for maintenance receptors, as described
above, the EPA identifies ``maintenance-only'' receptors as those
monitoring sites that have projected average design values above the
level of the applicable NAAQS, but that are not currently measuring
nonattainment based on the most recent official design values. In
addition, those monitoring sites with projected average design values
below the NAAQS, but with projected maximum design values above the
NAAQS are also identified as ``maintenance only'' receptors, even if
they are currently measuring nonattainment based on the most recent
official design values.
3. Step 2 of the 4-Step Interstate Transport Framework
In Step 2 the EPA quantifies the contribution of each upwind state
to each receptor in the 2023 analytic year. The contribution metric
used in Step 2 is defined as the average impact from each state to each
receptor on the days with the highest ozone concentrations at the
receptor based on the 2023 modeling. If a state's contribution value
does not equal or exceed the threshold of 1 percent of the NAAQS (i.e.,
0.70 ppb for the 2015 8-hour ozone NAAQS),
[[Page 31448]]
the upwind state is not ``linked'' to a downwind air quality problem,
and the EPA, therefore, concludes that the state does not significantly
contribute to nonattainment or interfere with maintenance of the NAAQS
in the downwind states. However, if a state's contribution equals or
exceeds the 1 percent threshold, the state's emissions are further
evaluated in Step 3, considering both air quality and cost as part of a
multi-factor analysis, to determine what, if any, emissions might be
deemed ``significant'' and, thus, must be eliminated under CAA section
110(a)(2)(D)(i)(I). The EPA is proposing to rely in the first instance
on the 1 percent threshold for the purpose of evaluating a state's
contribution to nonattainment or maintenance of the 2015 8-hour ozone
NAAQS (i.e., 0.70 ppb) at downwind receptors. This is consistent with
the Step 2 approach that the EPA applied in CSAPR for the 1997 ozone
NAAQS, which has subsequently been applied in the CSAPR Update when
evaluating interstate transport obligations for the 2008 ozone NAAQS.
The EPA continues to find 1 percent to be an appropriate threshold. For
ozone, as the EPA found in the Clean Air Interstate Rule (CAIR), CSAPR,
and CSAPR Update, a portion of the nonattainment problems from
anthropogenic sources in the U.S. results from the combined impact of
relatively small contributions from many upwind states, along with
contributions from in-state sources and, in some cases, substantially
larger contributions from a subset of particular upwind states. The
EPA's analysis shows that much of the ozone transport problem being
analyzed in this proposed rule is still the result of the collective
impacts of contributions from many upwind states. Therefore,
application of a consistent contribution threshold is necessary to
identify those upwind states that should have responsibility for
addressing their contribution to the downwind nonattainment and
maintenance problems to which they collectively contribute. Continuing
to use 1 percent of the NAAQS as the screening metric to evaluate
collective contribution from many upwind states also allows the EPA
(and states) to apply a consistent framework to evaluate interstate
emissions transport under the interstate transport provision from one
NAAQS to the next. See 81 FR 74504, 74518. See also 86 FR 23054, 23085
(reviewing and explaining rationale from CSAPR, 76 FR 48,208, 48237-38,
for selection of 1 percent threshold).
The EPA's August 2018 memorandum recognized that in certain
circumstances, a state may be able to establish that an alternative
contribution threshold of 1 ppb is justifiable. Where a state relies on
this alternative threshold, and where that state determined that it was
not linked at Step 2 using the alternative threshold, the EPA will
evaluate whether the state provided a technically sound assessment of
the appropriateness of using this alternative threshold based on the
facts and circumstances underlying its application in the particular
SIP submission.
4. Step 3 of the 4-Step Interstate Transport Framework
Consistent with the EPA's longstanding approach to eliminating
significant contribution or interference with maintenance, at Step 3,
states linked at Steps 1 and 2 are generally expected to prepare a
multifactor assessment of potential emissions controls. The EPA's
analysis at Step 3 in prior federal actions addressing interstate
transport requirements has primarily focused on an evaluation of cost-
effectiveness of potential emissions controls (on a marginal cost-per-
ton basis), the total emissions reductions that may be achieved by
requiring such controls (if applied across all linked upwind states),
and an evaluation of the air quality impacts such emissions reductions
would have on the downwind receptors to which a state is linked; other
factors may potentially be relevant if adequately supported. In
general, where the EPA's or alternative air quality and contribution
modeling establishes that a state is linked at Steps 1 and 2, it will
be insufficient at Step 3 for a state merely to point to its existing
rules requiring control measures as a basis for approval. In general,
the emissions-reducing effects of all existing emissions control
requirements are already reflected in the air quality results of the
modeling for Steps 1 and 2. If the state is shown to still be linked to
one or more downwind receptor(s), states must provide a well-documented
evaluation determining whether their emissions constitute significant
contribution or interference with maintenance by evaluating additional
available control opportunities by preparing a multifactor assessment.
While the EPA has not prescribed a particular method for this
assessment, the EPA expects states at a minimum to present a sufficient
technical evaluation. This would typically include information on
emissions sources, applicable control technologies, emissions
reductions, costs, cost effectiveness, and downwind air quality impacts
of the estimated reductions, before concluding that no additional
emissions controls should be required.\30\
---------------------------------------------------------------------------
\30\ As examples of general approaches for how such an analysis
could be conducted for their sources, states could look to the CSAPR
Update, 81 FR 74504, 74539-51; CSAPR, 76 FR 48208, 48246-63; CAIR,
70 FR 25162, 25195-229; or the NOX SIP Call, 63 FR 57356,
57399-405. See also Revised CSAPR Update, 86 FR 23054, 23086-23116.
Consistently across these rulemakings, the EPA has developed
emissions inventories, analyzed different levels of control
stringency at different cost thresholds, and assessed resulting
downwind air quality improvements.
---------------------------------------------------------------------------
5. Step 4 of the 4-Step Interstate Transport Framework
At Step 4, states (or the EPA) develop permanent and federally
enforceable control strategies to achieve the emissions reductions
determined to be necessary at Step 3 to eliminate significant
contribution to nonattainment or interference with maintenance of the
NAAQS. For a state linked at Steps 1 and 2 to rely on an emissions
control measure at Step 3 to address its interstate transport
obligations, that measure must be included in the state's SIP so that
it is permanent and federally enforceable. See CAA section 110(a)(2)(D)
(``Each such [SIP] shall . . . contain adequate provisions . . . .'').
See also CAA 110(a)(2)(A); Committee for a Better Arvin v. U.S. E.P.A.,
786 F.3d 1169, 1175-76 (9th Cir. 2015) (holding that measures relied on
by state to meet CAA requirements must be included in the SIP).
II. SIP Submission Addressing Interstate Transport of Air Pollution for
the 2015 8-Hour Ozone NAAQS
In California, the California Air Resources Board (CARB or
``State'') is the state agency responsible for the adoption and
submission to the EPA of California state, county, and local SIPs and
SIP revisions. CARB submitted its infrastructure SIP revision (``2018
Infrastructure SIP,'' ``California's 2018 Submittal,'', or ``2018
Submittal'') for the 2015 ozone NAAQS on October 1, 2018.\31\ In 2021,
the EPA finalized action on most of the ``infrastructure'' requirements
in that submittal but did not act on the interstate transport
requirements of 110(a)(2)(D)(i)(I).\32\ We are proposing action on the
interstate transport portions of California's 2018 Submittal in this
action.
---------------------------------------------------------------------------
\31\ Letter dated October 1, 2018, from Richard W. Corey,
Executive Officer, CARB, to Michael Stoker, Regional Administrator,
EPA Region IX.
\32\ 86 FR 16533 (March 30, 2021).
---------------------------------------------------------------------------
[[Page 31449]]
A. Information Provided at Steps 1 and 2
Enclosure 4 of California's 2018 Submittal contains the state's
``Good Neighbor State Implementation Plan.'' For Steps 1 and 2 of its
four-step analysis, California reviewed the results of the EPA's
modeling runs released with the January 2017 NODA, the October 2017
memorandum, and the March 2018 memorandum.\33\ CARB presented modeled
design values for monitoring sites that the modeling released with the
January 2017 NODA or the October 2017 memoranda projected to be
nonattainment or maintenance receptors in 2023, using the EPA's
definition of those terms.\34\ CARB explained it focused its evaluation
on receptor sites in Colorado and Arizona because those were the
western states, other than California, where the EPA's modeling
identified nonattainment or maintenance sites in 2023 using the data in
the March 2018 memorandum.\35\ Accordingly, CARB identified the
following receptor sites and modeled design values, noting that the
EPA's modeling released with the October 2017 memorandum and March 2018
memorandum yielded the same design values for 2023.\36\
---------------------------------------------------------------------------
\33\ California's 2018 Submittal, p. A4-10.
\34\ Id. at A4-11, Table 1.
\35\ Id. at A4-10.
\36\ Id.
Table 1--Modeled Receptor Design Values in Western States in California's 2018 Submittal
--------------------------------------------------------------------------------------------------------------------------------------------------------
January 2017 January 2017 October 2017 October 2017
modeling- modeling- modeling- modeling-
Site County AQS No. average 2023 maximum 2023 average 2023 maximum 2023
DV (ppb) DV (ppb) DV (ppb) DV (ppb)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Colorado
--------------------------------------------------------------------------------------------------------------------------------------------------------
Chatfield................................. Douglas..................... 08-035-0004 69.6 71.6 71.1 73.2
Rocky Flats North......................... Jefferson................... 08-059-0006 70.5 72.9 71.3 73.7
NREL...................................... Jefferson................... 08-059-0011 69.7 72.7 70.9 73.9
Fort Collins West......................... Larimer..................... 08-069-0011 68.6 70.4 71.2 73.0
Highland Reservoir........................ Arapahoe.................... 08-005-0002 68.0 70.0 69.3 71.3
Weld Co. Tower............................ Weld........................ 08-123-0009 67.2 68.3 70.2 71.4
--------------------------------------------------------------------------------------------------------------------------------------------------------
Arizona
--------------------------------------------------------------------------------------------------------------------------------------------------------
West Phoenix.............................. Maricopa.................... 04-013-0019 67.9 70.0 69.3 71.4
North Phoenix............................. Maricopa.................... 04-013-1004 68.7 69.8 69.8 71.0
--------------------------------------------------------------------------------------------------------------------------------------------------------
Source: California's 2018 Submittal, p. A4-11, Table 1.
To ``assess the potential for transport impacts from California to
Colorado receptors,'' CARB identified geographic and meteorologic
features of the Denver Metro/North Front Range nonattainment area.\37\
Geographic features identified by CARB included the Front Range,
extending up to 8,000 feet in elevation on the western side of the
metropolitan area, as well as mountains on the southern and
southeastern end of the area. CARB noted that both form barriers to air
flow.\38\ CARB also notes that to the east and north of the Denver area
are gradually rising hills that generally are open to airflow with the
Denver area. Meteorological conditions identified by CARB include
sunlight, temperature and winds conducive to formation of ozone, and
diurnal recirculation that allows emissions and ozone concentrations to
build up over multi-day periods.\39\ CARB additionally notes that this
terrain, combined with unique atmospheric conditions and high
temperatures during the summer months, are highly conducive to the
accumulation of local emissions and the formation of ozone in the
Denver-Aurora-Lakewood Core Based Statistical Area, and, additionally,
allows for ozone concentrations to remain higher for more hours,
leading to higher 8-hour averages at monitoring sites.
---------------------------------------------------------------------------
\37\ Id. at A4-13.
\38\ Id.
\39\ Id. at A4-13-A4-14.
---------------------------------------------------------------------------
CARB notes additional local features that contribute to high ozone
concentrations in the Denver nonattainment area, including upslope and
downslope flow in the foothill regions on broad high-pressure days near
several violating monitoring sites. CARB also claims that wildfires had
an impact on ozone concentrations in the Denver area, specifically
noting that on September 4, 2017, large wildfire events across five
western states brought plumes of smoke southward along the Front Range,
inevitably mixing with the surface, and as a result, elevated ozone
concentrations were observed at the Rocky Flats North site, reaching
0.078 ppm 8-hour average ozone concentrations.
CARB conducted a trajectory analysis from California to Colorado
using the National Oceanic and Atmospheric Administration (NOAA) Hybrid
Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model.\40\
CARB found that only two percent of nearly 500 backward trajectories
from Colorado receptor sites on high ozone days in June and July
(initiated from 10, 1000, and 2000 meters above ground level with a
duration of 96 hours) indicated air parcels may have traveled from a
mixed layer within California, where pollutants become well dispersed,
to a mixed layer at the Colorado receptor sites.\41\ CARB also found
only one forward trajectory (starting at 10 meters above the ground
with a duration of 96 hours) from the mixed layer in California reached
the mixed layer at a Colorado receptor site.\42\According to CARB, this
suggests that the complexity of the physical environment between
California and Colorado limits the reproducibility of modeled transport
and that considerable multi-faceted analyses would be necessary to
explore transport mechanisms through areas of complex terrain.\43\
---------------------------------------------------------------------------
\40\ Id. at A4-17.
\41\ Id. at A4-17-A4-18.
\42\ Id. at A4-18.
\43\ Id.
---------------------------------------------------------------------------
CARB's conclusion based on the HYSPLIT trajectories was that upper-
level air was almost always above the mixed layer over California,
Colorado, or both.\44\ Without vertical mixing of the air between the
mixed layer near the ground and the upper level, CARB
[[Page 31450]]
asserted, little to no impact from transport of emissions or pollutants
would be expected at the surface.\45\ CARB concluded that transport
from California emissions sources to Colorado is possible but extremely
unlikely on high ozone days at the Colorado receptor sites identified
by the EPA modeling.\46\ CARB also noted that this conclusion appeared
consistent with Colorado's weight of evidence (WOE) analysis for its
Denver Metro/North Front Range attainment plan SIP submittal for the
0.075 ppm 8-hour ozone standard.\47\
---------------------------------------------------------------------------
\44\ Id.
\45\ Id.
\46\ Id. at A4-18-A4-19.
\47\ Id. at A4-19.
---------------------------------------------------------------------------
CARB also attempted to rely on one of the preliminary ``potential
flexibilities'' in Attachment A to the EPA's March 2018 memorandum to
evaluate California's impacts on receptors in Colorado.\48\ CARB cited
the idea of ``consider[ing] removal of certain data from modeling
analysis for the purposes of projecting design values and calculating
the contribution metric where data removal is based on model
performance and technical analyses support the exclusion.'' \49\ In
making use of this potential flexibility, CARB used exceptional event
data from Colorado's ``weight of evidence'' (WOE) analysis included in
its Denver Metro/North Front Range attainment SIP submittal for the
0.075 ppm 8-hour ozone standard.\50\ CARB asserted that, although
Colorado did not submit formal demonstrations for these events under
the Exceptional Event Rule because they did not affect design values in
the area's attainment year, the EPA concurred with Colorado's
assessment that the model Colorado used for its Denver Metro/North
Front Range attainment SIP submittal was properly configured, met EPA
performance requirements, and was appropriately used in its
application.\51\
---------------------------------------------------------------------------
\48\ Id. at A4-23.
\49\ Id. at A4-23. See also March 2018 memorandum, Attachment A
at A-2.
\50\ California's 2018 Submittal at A4-23-A4-24 (citing 83 FR
14807 (April 6, 2018) and 83 FR 31068 (July 3, 2018)).
\51\ Id. at A4-23.
---------------------------------------------------------------------------
To recalculate projected design values excluding exceptional event
data flagged by Colorado, CARB first calculated design values from
prior years for the four monitors analyzed in Colorado's Denver Metro/
North Front Range attainment SIP submittal for the 2008 8-hour ozone
standard of 0.075 ppm (Chatfield, Rocky Flats North, NREL, and Fort
Collins West) as well as for two additional monitors: Highland
Reservoir and Weld Co. Tower.\52\ CARB found that the average design
values for the years 2009-2011, 2010-2012, and 2011-2013 dropped by 1-2
ppb at all six sites when data flagged by Colorado was excluded.\53\
CARB found that maximum base year design values dropped by 2-3 ppb.\54\
---------------------------------------------------------------------------
\52\ Id. at A4-23-A4-24.
\53\ Id. at A4-24.
\54\ Id.
---------------------------------------------------------------------------
CARB also attempted to replicate Colorado's future design value
calculations from Colorado's WOE analysis to be consistent with
Colorado's approach by using the ``el'' version of the emissions
inventory.\55\ CARB excluded Colorado's flagged events to recalculate
design values for future year modeling for 2023 based on EPA's Good
Neighbor SIP modeling released in the January 2017 NODA (using the
``el'' emissions inventory).\56\ CARB calculated that average design
values at the six sites dropped by 1 to 2 ppb, and maximum design
values dropped by 2 ppb.\57\ CARB found this resulted in no
nonattainment or maintenance receptors being projected in Colorado in
2023.\58\
---------------------------------------------------------------------------
\55\ Id. at A4-25
\56\ Id. at A4-26.
\57\ Id. A4-26.
\58\ Id.
---------------------------------------------------------------------------
CARB repeated the same process with EPA's Good Neighbor SIP
modeling released in the October 2017 memorandum using the ``en''
emissions inventory.\59\ CARB found that excluding data flagged by
Colorado reduced the 2023 average design values by 0-2 ppb and the
maximum design values by 1-2 ppb. CARB asserted that its approach was
consistent with Attachment A to the March 2018 memorandum with respect
to ``collaboration among states linked to a common receptor and among
linked upwind and downwind states in developing and applying a
regionally consistent approach.'' \60\
---------------------------------------------------------------------------
\59\ Id. at A4-27.
\60\ Id. at A4-23.
---------------------------------------------------------------------------
CARB analyzed the projected design values in the October 2017
memorandum and March 2018 memorandum in order to understand why the
2023 design values in Colorado were higher in the latter modeling
compared to the former.\61\ CARB noted that ``receptors'' in Colorado
based on the January 2017 modeling were clean in 2023 after removing
atypical events, but some of these sites became receptors in the March
2018 modeling even after atypical events were removed in the projection
of 2023 design values. CARB performed an analysis of contributions and
emissions to determine why four monitors in Denver changed from being
clean (after removing atypical events) in the older January 2017
modeling to maintenance-only receptors (after removing atypical events)
using the March 2018 modeling. CARB concluded that higher emissions,
and therefore higher contributions, from Colorado sources were the
primary reason why the four monitors changed from clean in the January
2017 modeling to maintenance-only in the March 2018 modeling. CARB used
this result to argue that emissions in Colorado, not California, are
responsible for the projected maintenance problem at these four
receptors.\62\ CARB also noted that differences in EPA's methodology
for calculating average contributions at individual monitors between
the January 2017 NODA and the March 2018 memorandum could have
contributed to the receptor changes that CARB identified in its
submittal. CARB further noted that the updated emissions inventory
(``en'') would not have accounted for Colorado's planned controls on
Colorado's nonpoint source emissions from oil and gas and therefore
overstated those emissions.\63\
---------------------------------------------------------------------------
\61\ Id. at A4-29.
\62\ Id. At A4-29--A4-33
\63\ Id. at A4-31-A4-32.
---------------------------------------------------------------------------
Ultimately, CARB decided it was more appropriate to rely on the
``en'' emissions inventory-based modeling released with the October
2017 memorandum, stating that this would be the more conservative
approach.\64\
---------------------------------------------------------------------------
\64\ Id. at A4-32-A4-33.
---------------------------------------------------------------------------
To analyze receptors in, and California's contributions to,
Arizona, CARB first noted that the EPA's modeling released with the
October 2017 memorandum identified the West Phoenix and North Phoenix
monitoring sites in the Phoenix-Mesa nonattainment area as potential
maintenance receptors, while the earlier version of the modeling
released with the January 2017 NODA did not project any receptors in
Arizona.\65\ CARB identified geographic features of the Phoenix-Mesa
nonattainment area, including the Sierra Estrella Mountains to the
southwest, the White Tank Mountains to the west, the Bradshaw Mountains
to the north and northeast, the Superstition Mountains to the east, and
the South Mountains to the south.\66\ CARB explained this ``topographic
bowl'' significantly limits air flow during non-stormy periods.\67\
CARB also identified meteorological factors affecting the Phoenix area,
such as upper-level high pressure systems over
[[Page 31451]]
the western U.S. that produce high temperatures, limit cloud formation,
and generally lead to light winds.\68\ Additional meteorological
factors identified by CARB included cooling in the evening that brings
emissions and pollutants back to the metropolitan area at night, the
summer monsoon, temperature inversions outside of monsoon season,
atmospheric mixing heights of several thousand feet on hot afternoons,
and ``dry'' thunderstorms that may ignite wildfires.\69\
---------------------------------------------------------------------------
\65\ Id. at A4-35.
\66\ Id.
\67\ Id. at A4-35.
\68\ Id. at A4-35-A4-36.
\69\ Id. at A4-26.
---------------------------------------------------------------------------
CARB also conducted a simplified, short-ranged trajectory
analysis.\70\ CARB viewed backward HYSPLIT model trajectories for the
two receptor sites in Arizona to evaluate the potential for transport
of ozone or ozone precursors from California. CARB concluded that air
is typically from within the Phoenix area for trajectories at 100 and
500 meters above ground level and that trajectories at 1000 meters are
most frequently from the north-northeast, southeast, or southwest. CARB
interpreted its analysis to suggest air from California was unlikely to
be a significant factor contributing to higher ozone values in
Phoenix.\71\
---------------------------------------------------------------------------
\70\ Id. at A4-39.
\71\ Id.
---------------------------------------------------------------------------
CARB then compared the two receptor sites' 2023 projections from
the two versions of transport modeling that EPA released in the January
2017 NODA (``el'' emissions inventory) and the October 2017 memorandum
(``en'' emissions inventory). CARB noted that the design values at the
two Arizona sites increased by 1-2 ppb from the earlier to the later
version of the EPA's modeling, and that based on the contribution data
included in the March 2018 memorandum, Arizona's own contribution
increased by 1.8-2.2 ppb.\72\ CARB concluded that the difference in
Arizona's design values appeared to be mainly driven from Arizona's own
contributions, and that the balance of difference between Arizona's
contributions and the changes to the design values came from emissions
categorized as ``Other'', which included emissions from Canada and
Mexico.\73\ Specifically, CARB noted that fire impacts increased at
both sites and that international contributions increased at the West
Phoenix site.\74\ At both sites, CARB explained that the home state's
contribution grew by more than the amount necessary to make the site a
maintenance receptor in modeling released with the October 2017
memorandum (using the ``en'' emissions inventory).\75\ CARB also noted
that, while Arizona's contribution increased from the modeling released
with the January 2017 NODA (``el'' emissions inventory) to the modeling
results released with the October 2017 memorandum (``en'' emissions
inventory), California's contribution decreased at both monitoring
sites between the same versions.\76\
---------------------------------------------------------------------------
\72\ Id. at A4-40.
\73\ Id. A4-40-A4-41.
\74\ Id. at A4-42.
\75\ Id. at A4-43.
\76\ Id.
---------------------------------------------------------------------------
CARB decided to give more weight to the modeling results released
with the October 2017 memorandum (``en'' emissions inventory),\77\
which indicated that California contributes above 1 percent of the
NAAQs to two maintenance receptors in Arizona. However, CARB concluded
that the differences between the modeling results based on the ``el''
and ``en'' emissions inventories resulting in increased modeled design
values for the two maintenance receptors in Arizona were not due to
increased contributions from California.\78\ Based on this information,
CARB found it ``reasonable to conclude that emissions from California
do not significantly interfere with attainment/maintenance of the 0.070
ppm 8-hour ozone NAAQS at the modeled ozone receptors in Arizona.''
\79\
---------------------------------------------------------------------------
\77\ Id. at A4-44.
\78\ Id.
\79\ Id.
---------------------------------------------------------------------------
Overall, California's conclusion for Step 2 was that it is linked
to downwind sites in Colorado and Arizona, based on the EPA modeling
results released with the October 2017 memorandum.\80\ However, based
on the additional analyses CARB provided at Step 2 (and further
analysis of emissions control measures provided at Step 3 of their
submittal), CARB concludes that California does not contribute
significantly to nonattainment or interfere with maintenance of the
2015 ozone NAAQS in other states.
---------------------------------------------------------------------------
\80\ Id.
---------------------------------------------------------------------------
B. Information Provided at Step 3
For Step 3, CARB reviewed and evaluated California's emissions
control measures.\81\ CARB noted that, based on the 2011 National
Emissions Inventory (NEI) and based on 2023 projected emissions, a
NOX control strategy would be most effective for reducing
regional scale ozone transport.\82\ Table 2 below shows California
emissions in 2011 and 2023 by sector and percentage.
---------------------------------------------------------------------------
\81\ Id. at A4-45.
\82\ Id. at A4-46.
Table 2--California Emissions in 2021 and 2023 by Sector and Percentage
--------------------------------------------------------------------------------------------------------------------------------------------------------
NOX VOCs
Modeled emissions by sector -----------------------------------------------------------------------------------------------
Mobile Stationary >Area Mobile Stationary Area
--------------------------------------------------------------------------------------------------------------------------------------------------------
Percent of 2011 NEI Emissions........................... 78.4 11.2 10.4 34.8 6.5 58.7
Percent of 2023 Projected Emissions..................... 67.1 26.9 6.0 28.6 29.3 42.1
--------------------------------------------------------------------------------------------------------------------------------------------------------
Source: California's 2018 Submittal, p. A4-46, Table 31.
CARB noted that a NOX-focused approach is consistent
with the EPA's historical focus for transport control measures, then
summarized its controls for mobile sources, stationary sources, and
consumer products.\83\
---------------------------------------------------------------------------
\83\ Id. at A4-46-A4-56.
---------------------------------------------------------------------------
CARB summarized its NOX controls for mobile sources,
including the Smog Check program, low emission vehicle fleet standards
and zero emission vehicle regulation, and California's reformulated
gasoline standard. CARB also described programs to reduce
NOX emissions from heavy-duty vehicles by nearly 70 percent
by 2023 and from off-road equipment by 45 percent by 2031. In the South
Coast Air Quality Management District, CARB stated that mobile source
control programs are projected to reduce NOX emissions by
153 tons per day (tpd) in 2023 and by 184 tpd by 2031. CARB also noted
that the federal government has primary regulatory authority over
mobile sources such as ocean-going vessels, aircraft, and
locomotives.\84\
---------------------------------------------------------------------------
\84\ Id. at A4-47-A4-48.
---------------------------------------------------------------------------
CARB also described NOX controls for stationary sources,
noting that California's 35 air districts have primary authority over
those sources. CARB
[[Page 31452]]
provided examples of prohibitory rules for NOX and VOC
already approved into the California SIP. These included rules
controlling VOC emissions from Graphic Arts Operations in the Ventura
County Air Pollution Control District (APCD), Placer County APCD, and
San Diego County APCD. Other examples included rules controlling
NOX emissions from Natural Gas-Fired Fan-Type Central
Furnaces and Small Water Heaters in Santa Barbara APCD, from Gasoline
Transfer and Dispensing in the South Coast Air Quality Management
District, from Natural Gas-Fired Water Heaters, Small Boilers, and
Process Heaters in Placer County APCD, and from Large Water Heaters and
Small Boilers in Ventura County APCD. Separately, CARB described
California's consumer product control program to regulate reactive
organic gas emissions, a subset of VOCs.\85\
---------------------------------------------------------------------------
\85\ Id. at A4-48-A4-53.
---------------------------------------------------------------------------
After summarizing these controls, CARB provided information about
its electric generating units (EGUs) and non-EGU stationary
sources.\86\ Noting that the EPA has historically targeted EGUs for
reductions in ozone transport pollution, CARB stated that the only two
EGUs in the state emitting NOX at rates higher than 0.061
lb/MMBtu are either ``unlikely'' to have further cost-effective
emission control opportunities or planned to retire by the end of
2019.\87\ CARB also explained that the only EGU emitting more than 250
tpy NOX in 2011 ceased operation in 2014, and that two EGUs
emitting over 100 tpy NOX in the San Joaquin Valley APCD
ceased operation in 2011.\88\
---------------------------------------------------------------------------
\86\ Id. at A4-54-A4-55.
\87\ Id. at A4-54.
\88\ Id. at A4-54-A4-55.
---------------------------------------------------------------------------
CARB also noted that in 2016, the EPA assessed further
NOX reductions from EGUs and that the CSAPR Update resulted
in a cost threshold of $1400 per ton.\89\ CARB stated that the EPA's
analysis showed ozone season EGU NOX reductions in
California would not occur until the $5000 per ton emissions-control
scenario.\90\ CARB concluded that due to ``strict and comprehensive
emissions regulations on emissions, EGUs do not appreciably contribute
to NOX such that the emissions could significantly
contribute to ozone formation in another state.'' \91\
---------------------------------------------------------------------------
\89\ Id. at A4-55.
\90\ Id.
\91\ Id.
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For non-EGUs, CARB noted that, although they emitted 6.7 times as
much NOX as EGUs did in 2011 in California, they only
represented 5.2 percent of the statewide NOX inventory.\92\
CARB concluded that, for the large non-EGU sources that are either
subject to NOX control measures that have not been submitted
for approval into the California SIP, or fall outside the geographic
jurisdiction of the applicable district rules, further emission
controls would be unlikely to reduce any potential impact on downwind
states' air quality because such sources comprise no more than 0.8
percent of the total NOX emitted in California in 2011.\93\
CARB also highlighted its consumer product control program, which
regulates reactive organic gas.\94\
---------------------------------------------------------------------------
\92\ Id.
\93\ Id., p. A4-55
\94\ Id. at A4-56.
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CARB's Step 3 conclusion was that ``the State's emission reduction
control system leads the nation in stringency for most sectors of
emission sources'' and that ``California's emission reduction programs
adequately prohibit the emission of air pollutants in amounts that will
significantly contribute to nonattainment, or interfere with
maintenance, of the 0.070 ppm 8-hour ozone standard in any downwind
state.'' \95\
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\95\ Id., p. A4-57
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C. Information Provided at Step 4
For its Step 4 analysis, CARB stated, ``Although linked to other
western states with projected air quality problems in 2023, California
is not significantly contributing to nonattainment or maintenance
problems in any other states. This is in large part due to the
stringency of California's air pollution control program. Therefore, no
further reductions or measures are necessary for Good Neighbor SIP
purposes.'' \96\
---------------------------------------------------------------------------
\96\ Id.
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CARB then provided a weight of evidence (WOE) analysis. The WOE
analysis purported to ``describe the U.S. EPA's contribution modeling
when grouping upwind states' contributions,'' asserted that transport
relationships among eastern and western states are different, and
argued that the role of interstate transport in western states is a
very small portion of projected design values and that the collective
impact of all upwind states is also a small portion.\97\ CARB also
asserted that previous rounds of EPA's photochemical modeling
identified smaller collective contribution for western states than
eastern states.\98\
---------------------------------------------------------------------------
\97\ Id. at A4-58-A4-69.
\98\ Id. at A4-59.
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CARB's WOE analysis further described differences it claims exist
between transport in eastern and western states.\99\ Differences
asserted by CARB included large populations in eastern states, the
relatively small size of eastern states and consequent high population
density, and numerous metropolitan areas in eastern states that cross
state boundaries. CARB also noted the complex topography in western
states, which presents a challenge to air quality modeling, as well as
the relative distances between nonattainment areas and emissions
sources in western states and the larger overall sizes of western
states compared to eastern states.\100\
---------------------------------------------------------------------------
\99\ Id. at A4-61-A4-67.
\100\ Id. at A4-63.
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CARB continued its WOE analysis by reiterating that California has
little impact on ozone levels outside its borders, specifically because
of the distance between California's eastern border and its emissions
sources, as well as because of the Sierra Nevada mountains, which limit
airflow from California to the east and which are sparsely
populated.\101\ CARB's WOE analysis concluded with a per-capita
NOX emissions comparison across the states, in which
California ranked nearly last (even though it ranked second highest in
total NOX emissions (after Texas)), and stated, ``U.S. EPA's
modeling of state contributions bears out the expectation that
California's impacts on other states would be very small.'' \102\
---------------------------------------------------------------------------
\101\ Id. at A4-67-A4-69.
\102\ Id. at A4-68.
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In summary, California's 2018 submittal concluded that, while
California is linked to receptors in Arizona and Colorado with
projected air quality problems in 2023, California is not significantly
contributing to nonattainment or maintenance problems in any other
states.\103\ Further, CARB asserted that its emissions reduction
programs adequately prohibit the emission of air pollutants for
transport purposes, and that California has already adopted and
implemented permanent and enforceable measures of sufficient stringency
to ensure that the state does not contribute significantly to ozone
nonattainment or maintenance problems in downwind states.\104\
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\103\ Id. at A4-72-A4-73.
\104\ Id. at A4-73-A4-74.
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III. EPA Evaluation
The EPA is proposing to find that California's 2018 SIP Submittal
does not meet the State's obligations with respect to prohibiting
emissions that contribute significantly to nonattainment or interfere
with maintenance of the 2015 8-hour ozone NAAQS in any other state
based on the EPA's evaluation of the SIP submission using the 4-step
interstate transport framework, and the EPA is
[[Page 31453]]
therefore proposing to disapprove California's 2018 SIP Submittal.
A. Evaluation of California Weight of Evidence Analysis
As an initial matter, the EPA will address CARB's ``WOE analysis''
that included the statement: ``[b]y not promulgating a version of the
CSAPR in the West, U.S. EPA could be viewed as tacitly acknowledging a
disparity in the significance of interstate transport of ozone between
western and eastern states.'' \105\ That is an incorrect
interpretation. The EPA took comment on including western states in the
CSAPR Update, but did not finalize due to the possibility that ``there
may be additional factors to consider in the EPA's and state's
evaluations'' such as unspecified ``geographically specific
factors[.]'' \106\ The EPA stated explicitly that even though no
western state was included in the CSAPR Update, ``western states are
not relieved of their statutory obligation to address interstate
transport under the [CAA] section 110(a)(2)(d)(i)(I)'' and that the
``EPA and western states, working together, are continuing to evaluate
interstate transport obligations on a case-by-case basis.'' \107\
---------------------------------------------------------------------------
\105\ Id. at A4-62.
\106\ 81 FR 74503, 74523.
\107\ Id.
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While the EPA has in limited circumstances found unique issues
associated with addressing ozone transport in western states, the EPA
has consistently applied the 4-step transport framework in western
states and has identified ozone transport problems in the west that are
similar to those in the east.\108\ For example, in a prior action
addressing California's interstate transport obligations for the 2008
ozone NAAQS, the EPA concluded that ``the collective contribution of
emissions from upwind states represent a considerable portion of the
ozone concentrations at the maintenance receptors in the Denver area.''
\109\ Similarly, the EPA's view in acting on Wyoming and Utah's 2008
ozone NAAQS SIP submittals was that ``the air quality problem in [the
Denver nonattainment area of Colorado] resulted in part from the
relatively small individual contribution of upwind states that
collectively contribute a larger portion of the ozone contributions
(9.7 percent), comparable to some eastern receptors . . . .'' \110\
---------------------------------------------------------------------------
\108\ See 81 FR 31513 (May 19, 2016) (Arizona); 83 FR 65093
(December 19, 2018) (California); 85 FR 26361 (May 4, 2020) (New
Mexico); 81 FR 71991 (Oct. 19, 2016) (Utah prong 2); 82 FR 9155
(February 3, 2017) (Utah prong 1); 84 FR 14270 (April 10, 2019)
(Wyoming).
\109\ 83 FR 5381 (February 7, 2018). See also 82 FR 9155, 9157
(February 3, 2017).
\110\ See 84 FR 3389, 3391 (Feb. 12, 2019). See also 81 FR
71991, 71994-95 (Oct. 19, 2016); 81 FR 28807, 28810 (May 10, 2016)
(Colorado receptors are impacted by interstate transport where total
upwind state contribution is 11 percent of the total ozone
concentration and five states were projected to be linked).
---------------------------------------------------------------------------
The remaining discussion in CARB's WOE analysis is of limited
relevance to the question of assessing interstate ozone transport.
CARB's description of western geography, settlement patterns, early
American expansionist policy, and historically low population density
do not overcome the fundamental conclusion from each successive round
of EPA modeling, discussed below: California contributes more than 1
percent of the 2015 ozone NAAQS to multiple nonattainment and/or
maintenance receptors in other states. As explained in further detail
below, the EPA has examined the reliability of its nationwide modeling
for characterizing ozone transport in the west and finds that the
modeling is reliable. The remainder of CARB's analysis at Steps 3 and 4
is not approvable. CARB did not adequately evaluate additional
emissions control opportunities to support its conclusion that
emissions from sources in California do not significantly contribute to
nonattainment or interfere with maintenance in other States. The EPA
acknowledges that California may have one of, if not the, most
stringent emissions control strategies in the country, but the state
remains obligated to analyze additional control opportunities once a
linkage has been established at Steps 1 and 2. Finally, while the EPA
approved California's transport SIP submittal for the 2008 ozone NAAQS
at Step 3 on the basis that the State's emissions were overall
relatively well-controlled, the EPA cannot reach the same conclusion
here for the more stringent 2015 ozone NAAQS. In particular, the EPA
finds persistent linkages between California and several out of state
receptors under the more stringent NAAQS. Further, the EPA finds based
on new modeling, see Section III.B. of this document, that the State
failed to adequately assess emissions control opportunities at certain
non-EGU facilities.
B. Evaluation of Information Provided by California Regarding Step 1
and 2
1. Different Versions of EPA Modeling and Regulatory Flexibility
At Step 1 and 2 of the 4-step interstate transport framework, CARB
assessed the EPA modeling released with the January 2017 NODA and the
October 2017 memorandum, noting they yielded the same design values to
identify nonattainment and maintenance receptors in Colorado and
Arizona in 2023.\111\ CARB used the EPA's modeling released with the
January 2017 NODA and the March 2018 memorandum to identify
California's contributions to receptors in Colorado and Arizona, and
decided to give more weight to the contribution modeling released with
the March 2018 memorandum (which was based on the ``en'' emissions
inventory).112 113 With regard to the Arizona receptors,
CARB compared different versions of the EPA's modeling and noted that
California's contribution decreased from the earlier to later modeling
versions, while Arizona's own emissions increased. Ultimately, CARB
chose to rely on the version of the EPA modeling that identified 2
receptors in Arizona, as well as contributions from California to those
receptors above 1 percent of the NAAQS.\114\ CARB acknowledged that
California is linked to downwind air quality problems in Arizona above
the 1 percent of the NAAQS threshold at Step 2.\115\
---------------------------------------------------------------------------
\111\ Id. at A4-11 and Table 1.
\112\ Id. at A4-33. A4-34, A4-36.
\113\ As explained in Section I, the October 2017 memorandum
provided projected ozone design values for 2023. The data released
in the March 2018 memorandum built off the information provided in
the October 2017 memorandum by including contribution data to assist
states in the development of their interstate transport SIPs for the
2015 ozone NAAQS.
\114\ Id. at A4-44.
\115\ Id.
---------------------------------------------------------------------------
With regard to receptors in Colorado, CARB likewise compared
different versions of the EPA's modeling. Additionally, however, CARB
attempted to rely on a potential ``flexibility'' identified in
Attachment A to the March 2018 memorandum to exclude exceptional events
flagged by Colorado in its Denver Metro/North Front Range attainment
SIP submittal for the 2008 ozone NAAQS to revise base year design
values. This analysis led CARB to conclude that there will be fewer
receptors in Colorado in 2023 than under either the EPA's modeled
design values released with the January 2017 NODA or the October 2017
memorandum: Zero nonattainment or maintenance receptors using the
January 2017 NODA version of EPA's modeling and the ``el'' emissions
inventory, and zero nonattainment and four maintenance receptors using
the October 2017 memorandum version of EPA's modeling and the ``en''
emissions inventory.
Nonetheless, CARB's analysis did not conclude that California was
not linked below 1 percent of the NAAQS to the
[[Page 31454]]
four maintenance sites it identified in Colorado. On the contrary, CARB
acknowledged that it chose to rely on the EPA modeling released with
the October 2017 memorandum (using the ``en'' emissions inventory) and
that California was linked to four maintenance receptors in Colorado
using that version of the modeling, even after CARB removed flagged
data.\116\
---------------------------------------------------------------------------
\116\ A4-33, A4-34.
---------------------------------------------------------------------------
As explained in Section I.D. above, the concepts presented in
Attachment A to the March 2018 memorandum were neither guidance nor
determined by the EPA to be consistent with the CAA. The EPA made clear
at the time that it would thoroughly review the technical and legal
justifications states put forward in relying on any concepts from
Attachment A to the March 2018 memorandum. In this case, what CARB
proposes is potentially consistent with the EPA's modeling guidance,
insofar as the EPA has recognized that it may be appropriate to exclude
certain flagged data associated with atypical events (e.g., wildfires)
when calculating base period design values to project to a future year.
However, CARB's removal of atypical data did not change its conclusion
that there are receptors in Colorado in 2023 and that California
contributes above 1 percent of the NAAQS to one or more of them.\117\
---------------------------------------------------------------------------
\117\ Id. at A4-44.
---------------------------------------------------------------------------
2. Wildfires
In response to California's claim that recorded violations at
projected receptors in both Colorado and Arizona are heavily influenced
by wildfires experienced in western states, the EPA acknowledges that
wildfires could influence downwind pollutant concentrations and that it
is likely that wildfires would occur in 2023 and future years. However,
there is no way to accurately forecast the timing, location, and extent
of fires across a future three-year period that would be used to
calculate ozone design values. In the EPA's CSAPR Update Modeling
provided in the March 2018 memorandum and in the EPA's 2016v2 emissions
platform based modeling, the EPA held the meteorological data and the
fire and biogenic emissions constant at base year levels in the future
year modeling, as those emissions are highly-correlated with the
meteorological conditions in the base year.
CARB's analysis focused on changes in air quality projections at
receptors after removing data associated with atypical events (e.g.,
wildfires) and questioned whether the number of receptors would be
diminished or be nonexistent by 2023 if those data were removed.
However, we note that measured design values at the identified Colorado
and Arizona receptors continue to have design values well in excess of
the 2015 ozone NAAQS, as shown in Tables 3 and 4 below.\118\
---------------------------------------------------------------------------
\118\ In addition, the EPA's most recent modeling identifies
receptors in 2023 in Utah, Nevada, and on tribal lands. Yuma,
Arizona is also identified as a receptor in EPA's most recent
modeling, while the Phoenix area no longer has receptors and now has
a longer timeframe for attainment due to proposed changes in
nonattainment classification. Projections for receptors that the
EPA's most recent modeling identifies are provided later in this
notice in Table 5.
\119\ Historic design values at individual monitoring sites
nationwide are provided in the file: 2010-2020 Design Values.xlsx
which is included in docket ID No. EPA-HQ-OAR-2021-0663. Design
value reports can also be obtained on EPA's website at https://www.epa.gov/air-trends/air-quality-design-values.
\120\ Design values obtained from https://www.epa.gov/air-trends/air-quality-design-values, April 21, 2022.
\121\ CARB presented data for these two Maricopa County monitors
in its submittal. Those monitors are no longer projected to be
receptors in the EPA's most recent modeling. However, Yuma, Arizona,
along with monitors in Utah, Nevada, and on tribal land, as
described in Table 5 of this notice, are still projected to be
receptors.
Table 3--Ozone Design Values for Denver Nonattainment Area Monitors \119\
--------------------------------------------------------------------------------------------------------------------------------------------------------
2014-2016 2015-2017 2016-2018 2017-2019 2018-2020
AQS site ID State County Design value Design value Design value Design value Design value
(ppb) (ppb) (ppb) (ppb) (ppb)
--------------------------------------------------------------------------------------------------------------------------------------------------------
80013001........................ Colorado.......... Adams............. 67 67 67 65 69
80050002........................ Colorado.......... Arapahoe.......... .............. .............. 73 74 77
80050006........................ Colorado.......... Arapahoe.......... 67 67 69 69 71
80310002........................ Colorado.......... Denver............ 66 68 69 68 70
80350004........................ Colorado.......... Douglas........... 77 77 78 78 81
80590005........................ Colorado.......... Jefferson......... 72 75 72 71 71
80590006........................ Colorado.......... Jefferson......... 77 77 78 76 79
80590011........................ Colorado.......... Jefferson......... 80 79 79 76 80
80690007........................ Colorado.......... Larimer........... 69 68 70 68 70
80690011........................ Colorado.......... Larimer........... 75 75 77 75 75
80691004........................ Colorado.......... Larimer........... 70 68 69 67 67
--------------------------------------------------------------------------------------------------------------------------------------------------------
Table 4--Ozone Design Values for Selected Arizona Monitors 120 121
--------------------------------------------------------------------------------------------------------------------------------------------------------
2014-2016 2015-2017 2016-2018 2017-2019 2018-2020
AQS site ID State County Design value Design value Design value Design value Design value
(ppb) (ppb) (ppb) (ppb) (ppb) \b\
--------------------------------------------------------------------------------------------------------------------------------------------------------
04-013-0019..................... Arizona........... Maricopa.......... 73 74 74 73 74
04-013-1004..................... Arizona........... Maricopa.......... 75 75 76 75 78
40278011........................ Arizona........... Yuma.............. 74 72 71 71 68
--------------------------------------------------------------------------------------------------------------------------------------------------------
While elevated ozone levels in some instances may be associated
with wildfires or other atypical events, presently neither Arizona or
Colorado have sought, nor has the EPA concurred on, exceptional events
demonstrations that would indicate official design values at these
monitors should be appreciably lower than presently reported.
3. Back Trajectory Analysis
For both Colorado and Arizona, CARB analyzed HYSPLIT back
trajectories, but these also did not affect CARB's conclusions
regarding California's linkages to downwind monitors.
[[Page 31455]]
HYSPLIT back trajectory analyses use archived meteorological modeling
that includes actual observed data (surface, upper air, airplane data,
etc.) and modeled meteorological fields to estimate the most likely
route of an air parcel transported to a receptor at a specified time.
The method essentially follows a parcel of air backward in hourly steps
for a specified length of time. HYSPLIT estimates the central path in
both the vertical and horizontal planes. The HYSPLIT central path
represents the centerline with the understanding that there are areas
on each side horizontally and vertically that also contribute to the
concentrations at the end point. The horizontal and vertical areas that
potentially contribute to concentrations at the endpoint grow wider
from the centerline the further back in time the trajectory goes.
Therefore, a HYSPLIT centerline does not have to pass directly over
emissions sources or emission source areas but merely relatively near
emission source areas for those areas to contribute to concentrations
at the trajectory endpoint. The EPA relies on back trajectory analysis
as a corollary analysis along with observation-based meteorological
wind fields at multiple heights to examine the general plausibility of
the photochemical model ``linkages.'' Because the back trajectory
calculations do not account for any air pollution formation,
dispersion, transformation, or removal processes as influenced by
emissions, chemistry, deposition, etc., the trajectories cannot be used
to develop quantitative contributions. Therefore, back trajectories
cannot be used to quantitatively evaluate the magnitude of the existing
photochemical contributions from upwind states to downwind receptors.
In this regard, photochemical modeling simulations for ozone interstate
transport assessments are relied upon by the EPA to simulate the
formation and fate of oxidant precursors, primary and secondary
particulate matter concentrations, and deposition over regional and
urban spatial scales. Photochemical modeling is the most sophisticated
tool available to estimate future ozone levels and contributions to
those modeled future ozone levels. Consideration of the different
processes that affect primary and secondary pollutants at the regional
scale in different locations is fundamental to understanding and
assessing the effects of emissions on air quality concentrations.
CARB's HYSPLIT back trajectory analysis showed that on high ozone
days in Colorado at the receptors identified by the EPA in the March
2018 memorandum ``only one backward and forward trajectory pairing
indicated that emissions in the California mixed layer should have
reached the mixed layer at a Colorado receptor site.'' CARB claims this
suggests that ``the complexity of the physical environment between
California and Colorado limits the reproducibility of modeled transport
and that considerable multi-faceted analyses would be necessary to
explore transport mechanisms through areas of complex terrain.'' \122\
For Arizona, CARB concluded that ``[o]nly a few trajectories extend
from California'' to the Phoenix area.\123\ CARB's trajectory analysis
confirmed that California is an upwind area for the receptors in
Colorado and Arizona often enough to potentially contribute to
nonattainment or interfere with maintenance. The analysis did not
provide evidence that was contrary to the conclusions of the EPA's
photochemical modeling analyses (i.e., the EPA's modeling results in
the March 2018 memorandum and EPA 2016v2 model).
---------------------------------------------------------------------------
\122\ Id. at A4-18, A4-34.
\123\ Id. at A4-39, A4-40 Figure 5.
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Further, the EPA finds CARB's back trajectory analysis to be
deficient in proving that California does not contribute significantly
to nonattainment or maintenance at the monitors in Colorado that the
State was linked to in the EPA's modeling results in the March 2018
memorandum. CARB's back trajectory analysis for Colorado shows a
linkage between California and the monitors when evaluating three
altitudes: 10 meters, 1,000 meters, and 2,000 meters, during June and
July, when most exceedances occurred at these sites. By only evaluating
these altitudes, CARB neglects to consider the wide range of heights
that might show back trajectories leading back to sources in
California, which could potentially further tie the state to more ozone
exceedance events. In addition, by excluding trajectories with a
centerline above the mixed layer the analysis fails to consider
transported pollutants at elevations below the centerline which may be
in the mixed layer and therefore impact ground level ozone
concentrations.
Similarly for its analysis of Arizona linkages, CARB's back
trajectory analysis shows a linkage between California and the monitors
when evaluating three altitudes: 100 meters, 500 meters, and 1,000
Meters on ozone exceedance days in 2015 and 2016. CARB's back
trajectories for Arizona use a relatively short 24-hour time period,
which limits their reliability for evaluating long-distance transport
of emissions. As evident from Figure 5 in CARB's SIP submission, there
were a number of exceedance days in Phoenix with 24-hour back
trajectories that point westward toward California. These trajectories
may have crossed portions of California if the trajectories were
calculated for a longer time period, such as 48 hours. This would
further strengthen the linkage to California that is already indicated
by CARB's analysis.
In California's 2018 submittal, CARB noted that projected 2023 DVs
in Denver and Phoenix increased from the ``el'' modeling released in
the January 2017 NODA and the ``en'' modeling released in the October
2017 memorandum. For Denver, CARB noted that there were three 2023
receptors, all maintenance-only, based on the ``el'' modeling, whereas
with the ``en'' modeling projected three monitors to be nonattainment
and three monitors to be maintenance-only. For Phoenix, CARB noted that
there were no receptors projected for 2023 based on the ``el''
modeling, whereas with the ``en'' modeling, two monitors are projected
to be maintenance-only. Based on an analysis of the change in ``home
state'' emissions and contributions vs contributions and emissions from
California in the ``el'' modeling vs the ``en'' modeling, CARB argues
that the nonattainment and maintenance receptors found in the ``en''
modeling in Denver and Phoenix are due to increases in emissions in the
``home state'' rather than contributions from California.
With respect to the information California provided that is related
to local emissions and the impact on air quality at the Denver
nonattainment area receptors, this information is insufficient to
approve California's 2018 SIP submittal. As an initial matter, we do
not agree with CARB's conclusions that the remaining nonattainment or
maintenance problems in Arizona or in Colorado (after accounting for
flagged data) should be ascribed solely to an increase in local
emissions in the home state. While CARB asserts that its relative
contribution to the problems has declined, CARB does not establish with
any quantitative evidence that this contribution drops below 1 percent
of the NAAQS.
More fundamentally, regardless of whether local emissions are the
largest contributor to a specific nonattainment or maintenance
receptor, the good neighbor provision requires that upwind states
prohibit emissions that contribute significantly to nonattainment or
interfere with maintenance of the NAAQS in downwind states. The EPA
[[Page 31456]]
evaluates a state's obligations to eliminate interstate transport
emissions under the interstate transport provision according to the
EPA's 4-step process, and the EPA's updated modeling at Steps 1 and 2
has identified a linkage between emission from California sources and
downwind nonattainment and maintenance receptors.
Further, the EPA disagrees with the implication that local
emissions reductions from the jurisdiction where the downwind receptor
is located must first be implemented and accounted for before imposing
obligations on upwind states under the interstate transport provision.
There is nothing in the CAA that supports that position, and it does
not provide grounds on which to approve California's 2018 SIP
submittal. The D.C. Circuit has held on five different occasions that
the timing framework for addressing interstate transport obligations
must be consistent with the downwind areas' attainment schedule. In
particular, for the ozone NAAQS, the states and the EPA are to address
interstate transport obligations ``as expeditiously as practicable''
and no later than the attainment schedule set in accordance with CAA
section 181(a). See North Carolina, 531 F.3d at 911-13; Wisconsin, 938
F.3d at 313-20; Maryland, 958 F.3d at 1204; New York v. EPA, 964 F.3d
1214, 1226 (D.C. Cir. 2020); New York v. EPA, 781 Fed. App'x 4, 6-7
(D.C. Cir. 2019). The court in Wisconsin explained its reasoning in
part by noting that downwind jurisdictions often may need to heavily
rely on emissions reductions from upwind states in order to achieve
attainment of the NAAQS, 938 F.3d at 316-17; such states would face
increased regulatory burdens including the risk of bumping up to a
higher nonattainment classification if attainment is not reached by the
relevant deadline. Maryland, 958 F.3d at 1204. The statutory framework
of the CAA and these cases establish clearly that states and the EPA
must address interstate transport obligations in line with the
attainment schedule provided in the Act in order to timely assist
downwind states in attaining and maintain the NAAQS, and this schedule
is ``central to the regulatory scheme.'' Wisconsin, 938 F.3d at 316
(quoting Sierra Club v. EPA, 294 F.3d 155, 161 (D.C. Cir. 2002)).
Additionally, the 2018 SIP submittal does not assess whether
California's own emissions contributed to nonattainment or interfered
with maintenance at the linked receptors, or substantiate that
emissions from California's sources were not interacting with these
monitors. Consequently, the application of local emission reduction
measures does not absolve upwind states and sources from the
responsibility of addressing their significant contribution. Moreover,
California still has an obligation under the Act to address its
downwind contribution to ozone nonattainment or interference with
maintenance regardless of the emission reduction potential for local
control measures. Furthermore, given that the EPA's updated modeling
indicates that California is linked to nonattainment and maintenance
receptors at Step 2, the EPA disagrees with CARB's claims regarding the
application of local emission reduction measures with respect to its
downwind linkages in the most recent modeling.
CARB presents a number of arguments that the unique topography and/
or meteorology in the western region and, in particular, in and
surrounding the Denver and Phoenix nonattainment areas support a
conclusion that California does not significantly contribute or
interfere with maintenance in those areas. For example, CARB argues
that the mountainous topography in California traps ozone-precursors
in-state, and that the Rocky Mountains in Colorado and the mountains
around Phoenix, Arizona also form barriers to the transport of ozone
pollution.\124\ First, we note that despite these potential
considerations, CARB itself acknowledges in its 2018 submittal that
California is linked to at least some receptors in Colorado and Arizona
at Step 2 based on the modeling analysis on which it primarily relies.
Second, even if CARB intended these arguments to support an alternative
argument that it is not linked to those receptors, the EPA finds that
these entirely qualitative discussions are insufficient to overcome the
robust, quantitative basis to find linkages exist based on the
modeling.
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\124\ See, e.g., A4-13-14.
---------------------------------------------------------------------------
We agree with CARB that the terrain in the western U.S. is complex.
A complex topography can have a number of impacts on the transport of
air and air pollutants, such as enhance vertical mixing of air, serve
as a barrier to transported air pollution, enhance accumulation of
local emissions in basins and valleys, and influence air flows up,
down, and across valleys. While topography can have a significant
effect on pollutant (e.g., ozone) formation and transport, it does not
prevent transport within the State and beyond. Mountain passes through
surrounding ranges can serve as ``transport corridors'' for ozone. For
example, in Southern California, areas where upwind pollution is
funneled through valley topography experience some of the highest
measured ozone concentrations, despite lower local emissions.
In Southern California there are several examples of transport
corridors that funnel ozone and ozone precursors. The Riverside County
(Coachella) 2015 8-hour ozone NAAQS design value for 2020 was 88 ppb.
The area is affected by transported emissions from the South Coast Air
Basin through the San Gorgonio Pass.\125\ Similarly, the Kern County
(Eastern Kern), CA 2015 8-hour ozone NAAQS design value for 2020 was 86
ppb and is primarily influenced by emissions transported from the San
Joaquin Valley through the Tehachapi Pass.126 127 Ozone and
its precursors can be transported into the southern Mojave Desert Air
Basin from the greater Los Angeles Air Basin through the Cajon Pass.
Ozone can also be transported eastward to the Salton Sea Air Basin
through the San Gorgonio Pass and from the San Diego Air Basin through
other mountain passes continuing into Arizona. In addition to transport
within the mixed layer, orographic lifting of ozone from the surface to
the free troposphere by the so called ``mountain chimney effect'' is a
potential additional pathway for venting of pollutants into the free
troposphere and making them available for long-range transport to
downwind states (Langford et. al., 2010 and Li et. al.,
2015).128 129 While Southern California offers evidence of
funneling of pollution through mountain passes and upwelling of
pollution into troposphere, we have no reason to conclude these effects
could
[[Page 31457]]
not occur in the Sierra Nevada Mountains and the Denver Metro/North
Front Range.
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\125\ Final 2016 Air Quality Management Plan, at 7-23, South
Coast Air Quality Management District, March 2017.
\126\ Historic design values at individual monitoring sites
nationwide are provided in the file: 2010-2020 Design Values.xlsx
that is included in docket ID No. EPA-HQ-OAR-2021-0663. Design value
reports can also be obtained on EPA's website at https://www.epa.gov/air-trends/air-quality-design-values.
\127\ See ``CALIFORNIA Final Area Designations for the 2015
Ozone National Ambient Air Quality Standards Technical Support
Document (TSD)'' at pg 67, 178; available in docket ID No. EPA-HQ-
OAR-2017-0548 (83 FR 25776, April 30, 2018). Also available on EPA's
website at https://www.epa.gov/sites/default/files/2018-05/documents/ca_tsd_combined_final_0.pdf.
\128\ Langford, A., Senff, C., Alvarez, R., Banta, R., Hardesty,
R.: Long[hyphen]range transport of ozone from the Los Angeles Basin:
A case study, J. Geophys. Res., 37, L06807, doi:10.1029/
2010GL042507.
\129\ Li, J., Georgescu, M., Hyde, P., Mahalov, A., and
Moustaoui, M.: Regional-scale transport of air pollutants: Impacts
of Southern California emissions on Phoenix ground-level ozone
concentrations, Atmos. Chem. Phys., 15, 9345-9360, https://doi.org/10.5194/acp-15-9345-2015, 2015.
---------------------------------------------------------------------------
The EPA has previously explained that its nationwide photochemical
grid modeling is reliable for applications in the western region of the
U.S. In disapproving Utah's 2008 ozone transport SIP submittal for
prong 2, the EPA rejected comments that its CAMx modeling (the same
modeling software used here) did not account for unique western
geographical considerations. See 81 FR 71991, 71992-93 (Oct. 19, 2016).
In particular, the EPA noted that the modeling accounted for
differences in emissions (including wildfires), meteorology, and
topography'' across all regions of the U.S. Id. at 71993. The EPA found
that neither the commenters, nor the state in its SIP submittal, had
adduced any additional factors that would be relevant for projecting
ozone concentrations in the west that were not already factored into
and documented in both the modeling itself and in the EPA's technical
support documents explaining that modeling. Id. The same holds true
here. As explained in Appendix A of the Air Quality Modeling TSD
included in docket ID No. EPA-HQ-OAR-2021-0663, the EPA has found that
its updated 2016v2 emissions platform-based modeling performs equally
as well in eastern and western regions in terms of replicating the
relative magnitude of concentrations and day-to-day variability that
are characteristic of observed 8-hour daily maximum ozone
concentrations in each region. It is also important to note that the
model accurately captures substantial geographical difference in the
temporal nature of ozone concentrations at the receptors in the west,
including in the Denver nonattainment area, compared to receptors in
the East.\130\ The EPA continues to find its modeling reliable for
characterizing ozone concentrations and contribution values in the
western region of the United States. As such, CARB's qualitative
discussions of western geography fail to present evidence that calls
into question the results of the EPA's photochemical grid modeling.
---------------------------------------------------------------------------
\130\ See Appendix A--Model Performance Evaluation for 2016v2
Base Year CAMx Simulation, of Air Quality Modeling TSD for 2015
Ozone NAAQS Transport SIP Proposed Actions, at A-10.
---------------------------------------------------------------------------
C. Results of the EPA's Step 1 and Step 2 Modeling and Findings for
California
As described in section I, the EPA performed air quality modeling
using the 2016v2 emissions platform to project design values and
contributions for 2023. These data were examined to determine if
California contributes at or above the threshold of 1 percent of the
2015 8-hour ozone NAAQS (0.70 ppb) to any downwind nonattainment or
maintenance receptor. As shown in Table 3, the data \131\ indicate that
in 2023, emissions from California contribute greater than 1 percent of
the standard (i.e., 0.70 ppb) to nonattainment or maintenance-only
receptors in Arizona, Colorado, Nevada, and Utah.\132\ Emissions from
California also contribute greater than 1 percent of the standard to
nonattainment receptors on, or representative of, the Morongo and
Pechanga reservations.\133\
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\131\ Design values and contributions at individual monitoring
sites nationwide are provide in the file:
2016v2_DVs_state_contributions.xlsx which is included in docket ID
No. EPA-HQ-OAR-2021-0663.
\132\ These modeling results are consistent with the results of
a prior round of 2023 modeling using the 2016v1 emissions platform
which became available to the public in the fall of 2020 in the
Revised CSAPR Update, as noted in Section I. That modeling showed
that California had a maximum contribution greater than 0.70 ppb to
at least one nonattainment or maintenance-only receptor in 2023.
These modeling results are included in the file ``Ozone Design
Values and Contributions Revised CSAPR Update.xlsx'' in docket EPA-
HQ-OAR-2021-0663.
\133\ We note that, consistent with the EPA's prior good
neighbor actions in California, the regulatory ozone monitor located
on the Morongo Band of Mission Indians (``Morongo'') reservation is
a projected downwind receptor in 2023. See monitoring site 060651016
in Table 3. We also note that the Temecula, California regulatory
ozone monitor is a projected downwind receptor in 2023 and in past
regulatory actions has been deemed representative of air quality on
the Pechanga Band of Luise[ntilde]o Indians (``Pechanga'')
reservation. See, e.g., Approval of Tribal Implementation Plan and
Designation of Air Quality Planning Area; Pechanga Band of
Luise[ntilde]o Mission Indians, 80 FR 18120, at 18121-18123 (April
3, 2015); see also monitoring site 060650016 in Table 3. The
presence of receptors on, or representative of, the Morongo and
Pechanga reservations does not trigger obligations for the Morongo
and Pechanga Tribes. Nevertheless, these receptors are relevant to
the EPA's assessment of any linked upwind states' good neighbor
obligations. See, e.g., Approval and Promulgation of Air Quality
State Implementation Plans; California; Interstate Transport
Requirements for Ozone, Fine Particulate Matter, and Sulfur Dioxide,
83 FR 65093 (December 19, 2018). Under 40 CFR 49.4(a), tribes are
not subject to the specific plan submittal and implementation
deadlines for NAAQS-related requirements, including deadlines for
submittal of plans addressing transport impacts.
---------------------------------------------------------------------------
Therefore, based on the EPA's evaluation of the information
submitted by California, and based on the EPA's most recent modeling
results for 2023, the EPA proposes to find that California is linked at
Steps 1 and 2 and has an obligation to assess potential emissions
reductions from sources or other emissions activity at Step 3 of the 4-
step framework.
Table 5--California Linkage Results Based on EPA Updated 2023 Modeling
----------------------------------------------------------------------------------------------------------------
2023 Average 2023 Maximum California
Receptor ID Location Nonattainment/ design value design value contribution
maintenance (ppb) (ppb) (ppb)
----------------------------------------------------------------------------------------------------------------
40278011............ Yuma (AZ)...... Maintenance-only......... 70.5 72.2 5.09
80350004............ Denver/ Nonattainment............ 71.7 72.3 0.91
Chatfield (CO).
80590006............ Rocky Flats Nonattainment............ 72.6 73.3 1.03
(CO).
80590011............ Denver/NREL Nonattainment............ 73.8 74.4 1.17
(CO).
320030075........... Las Vegas/ Maintenance-only......... 70.0 71.0 7.44
Northwest (NV).
490110004........... SLC/Bountiful Nonattainment............ 72.9 75.1 2.25
(UT).
490353006........... SLC/Hawthorne Nonattainment............ 73.6 75.3 2.46
(UT).
490353013........... SLC/Herriman Nonattainment............ 74.4 74.9 1.42
(UT).
490570002........... SLC/Ogden (UT). Maintenance-only......... 70.6 72.5 2.24
490571003........... SLC/ Maintenance-only......... 70.5 71.5 2.16
Harrisonville
(UT).
060651016........... Morongo Band of Nonattainment............ 89.8 90.9 34.24
Mission
Indians.
060650016........... Pechanga Band Nonattainment............ 72.0 72.9 26.32
of Mission
Indians
(represented
by Temecula
(CA)).
----------------------------------------------------------------------------------------------------------------
[[Page 31458]]
Based on the EPA's evaluation of the information provided in
California's 2018 submittal and based on the results of the EPA's
2016v2 emissions platform modeling, the EPA will proceed to evaluate
these additional arguments at Step 3 of the 4-step interstate transport
framework.
D. Evaluation of Information Provided Regarding Step 3
At Step 3 of the 4-step interstate transport framework, a state's
emissions are further evaluated, in light of multiple factors,
including air quality and cost considerations, to determine what, if
any, emissions significantly contribute to nonattainment or interfere
with maintenance and, thus, must be eliminated under CAA section
110(a)(2)(D)(i)(I).
To effectively evaluate which emissions in the state should be
deemed ``significant'' and therefore prohibited, states generally
should prepare an accounting of sources and other emissions activity
for relevant pollutants and assess potential, additional emissions
reduction opportunities and resulting downwind air quality
improvements. The EPA has consistently applied this general approach
(i.e., Step 3 of the 4-step interstate transport framework) when
identifying emissions contributions that the Agency has determined to
be ``significant'' (or interferes with maintenance) in each of its
prior federal, regional ozone transport rulemakings, and this
interpretation of the statute has been upheld by the Supreme Court. See
EME Homer City, 572 U.S. 489, 519 (2014). While the EPA has not
directed states that they must conduct a Step 3 analysis in precisely
the manner the EPA has done in its prior regional transport
rulemakings, state implementation plans addressing the obligations in
CAA section 110(a)(2)(D)(i)(I) must prohibit ``any source or other type
of emissions activity within the State'' from emitting air pollutants
which will contribute significantly to downwind air quality problems.
Thus, states must complete something similar to the EPA's analysis (or
an alternative approach to defining ``significance'' that comports with
the statute's objectives) to determine whether and to what degree
emissions from a state should be ``prohibited'' to eliminate emissions
that will ``contribute significantly to nonattainment in, or interfere
with maintenance of'' the NAAQS in any other state. California did not
conduct such an analysis in its 2018 SIP Submittal.
As previously indicated in section II.B. California's 2018 SIP
Submittal provided an overview of NOX emissions by sector
for 2011 NEI emissions and 2023 projections. CARB also provided a
summary of regulations controlling NOX and VOCs at the state
and district level for various sectors, many of which had been approved
into California's SIP. CARB asserted in the 2018 Submittal that,
despite its contributions, California had met its good neighbor
obligations through the implementation and enforcement of stringent
NOX and VOC control measures that go beyond the EPA's
presumptive cost threshold in the CSAPR Update for highly cost-
effective emissions reductions, and through the ongoing adoption and
revision of additional control measures to further ensure the reduction
of ozone in both California and downwind areas.
CARB, however, did not provide an adequate demonstration at Step 3
that California was adequately controlling its emissions for the
purposes of the good neighbor provision for the 2015 ozone NAAQS,
particularly because CARB acknowledged in its 2018 SIP Submittal that
its emissions were linked to Arizona and Colorado receptors at Steps 1
and 2. In general, the air quality modeling that the EPA has conducted
as well as the modeling relied on by CARB in its submittal already
account for ``on-the-books'' emissions control measures. Both sets of
modeling analyzed by CARB (confirmed by the EPA's most recent modeling)
clearly establish continued linkages from California to downwind
receptors in 2023 at Steps 1 and 2. In general, the listing of existing
or on-the-way control measures, whether approved into the state's SIP
or not, does not substitute for a complete Step 3 analysis under the
EPA's 4-Step framework to define ``significant contribution.'' \134\
CARB's submittal does not include an assessment of the overall effects
of the identified control measures it identifies or explain what the
overall resulting air quality effects would be at identified out-of-
state receptors.
---------------------------------------------------------------------------
\134\ See discussion further in this Section discussing why EPA
finds its analysis in the approval of California's 2008 ozone NAAQS
transport SIP to be appropriate or sufficient for purposes of this
action.
---------------------------------------------------------------------------
Further, CARB did not conduct in its submittal any analysis of
potential additional emissions-reduction measures to further reduce its
impact on the identified downwind receptors. For example, CARB did not
include in the 2018 SIP Submittal an accounting of facilities in the
State along with an analysis of potential NOX emissions
control technologies, their associated costs, estimated emissions
reductions, and downwind air quality improvements. Nor does the
submittal include an analysis of whether such potential additional
control technologies or measures could reduce the impact of
California's emissions on out of state receptors. Though there is not a
prescribed method for a Step 3 analysis, the EPA has consistently
applied Step 3 of the good neighbor framework through a more rigorous
evaluation of potential additional control technologies or measures
than what was provided in the SIP submission. Identifying a range of
various emissions controls measures that have been or may be enacted at
the state or local level, without analysis of the impact of those
measures on the out of state receptors, is not analytically sufficient.
CARB did not offer an explanation as to whether any more stringent
emissions reductions that may be available were prohibitively costly or
infeasible. CARB did note that the EPA's 2016 cost-effectiveness
analysis of EGU emission reductions in the CSAPR Update for the 2008
ozone NAAQS found that NOX emission reductions at California
EGUs would be achieved at a significantly higher cost threshold than
the cost threshold finalized for the states ultimately included in the
CSAPR Update. CARB further stated that what the ``EPA found true with
respect to the 0.075 ppm 8-hour ozone standard is equally valid
concerning the 0.070 ppm 8-hour ozone standard. California's emission
reduction programs adequately prohibit the emission of air pollutants
in amounts that will significantly contribute to nonattainment, or
interfere with maintenance, of the 0.070 ppm 8-hour ozone standard in
any downwind state.'' \135\
---------------------------------------------------------------------------
\135\ Id. at A4-57.
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However, this is incorrect. There is no reason to suppose that the
EPA or states should conclude that the same degree of emissions-control
stringency that was deemed approvable to address good neighbor
obligations to meet a less stringent NAAQS should apply to a more
stringent NAAQS. While the EPA has not finalized a benchmark cost-
effectiveness threshold for good neighbor obligations for the more
stringent 2015 ozone NAAQS, it was not the EPA's obligation to do so
prior to states developing their SIP submissions.\136\ CARB, in its
2018 SIP
[[Page 31459]]
Submittal, has not conducted an analysis to establish one for the EPA
to evaluate, and this is grounds for disapproval.
---------------------------------------------------------------------------
\136\ The EPA notes that it has proposed a cost-effectiveness
threshold of $11,000 per ton for EGUs in determining good neighbor
obligations for the 2015 ozone NAAQS after assessing the full range
of NOX mitigation strategies that could be applied to
fossil-fuel fired EGUs. ``Federal Implementation Plan Addressing
Regional Ozone Transport for the 2015 Ozone National Ambient Air
Quality Standard'' 87 FR 20036, 20091-93 (April 6, 2022). While this
does not represent a final promulgated cost-effectiveness benchmark
for EGUs that California is expected to have applied, the EPA's Step
3 analysis in the proposed FIP indicates the relative paucity of
analysis in California's SIP submittal regarding emissions control
opportunities at Step 3. Nonetheless, the EPA has not proposed to
apply the EGU control strategy in its proposed FIP action to
California. See id. at 20088. The EPA continues to find in this
proposal that California's EGUs are sufficiently controlled for
ozone-precursor emissions for purposes of good neighbor obligations
under the 2015 ozone NAAQS.
---------------------------------------------------------------------------
More fundamentally, relying on the CSAPR Update's (or any other CAA
program's) determination of cost-effectiveness without further Step 3
analysis is insufficient. Cost-effectiveness must be assessed in the
context of the specific CAA program; assessing cost-effectiveness in
the context of interstate ozone transport should reflect a more
comprehensive evaluation of the nature of the interstate transport
problem, the total emissions reductions available at several cost
thresholds, and the air quality impacts of the reductions at downwind
receptors. While the EPA has not finalized a benchmark cost-
effectiveness value for the 2015 ozone NAAQS interstate transport
obligations, because the 2015 ozone NAAQS is a more stringent and more
protective air quality standard, it is reasonable to expect control
measures or strategies to address interstate transport of ozone to
reflect higher marginal control costs. As such, the marginal cost
threshold of $1,400 per ton for the CSAPR Update (which addresses the
2008 ozone NAAQS and is in 2011$) is not an appropriate cost threshold
and cannot be approved as a benchmark to use for interstate transport
SIP submissions for the 2015 ozone NAAQS.
Although the EPA acknowledges states are not necessarily bound to
follow the EPA's own analytical framework at Step 3, CARB did not
attempt to determine or justify an appropriate uniform cost-
effectiveness threshold. This would have been similar to the approach
to defining significant contribution that the EPA has applied in prior
rulemakings such as CSAPR and the CSAPR Update, even if conducting
precisely this type of analysis is not technically mandatory. For
example, CARB did not conduct its own updated EGU analysis of all large
NOX emitting EGUs. Nonetheless, the EPA finds based on its
own analysis that additional emissions reductions are not required from
EGUs to address California's good neighbor obligations for the 2015
ozone NAAQS.\137\
---------------------------------------------------------------------------
\137\ The EPA reached this proposed conclusion for EGUs in
California in the context of a recent proposed federal
implementation plan and proposes the same conclusions for these
sources in this action. See ``Federal Implementation Plan Addressing
Regional Ozone Transport for the 2015 Ozone National Ambient Air
Quality Standard,'' 87 FR 20036, 20088 (April 6, 2022).
---------------------------------------------------------------------------
As stated in the SIP submittal, the Greenleaf One unit emits at
higher rates with a low utilization, resulting in only 2 tons of
NOX in the 2021 ozone season. Therefore, the EPA agrees it
is unlikely that any significant cost-effective emission reduction
opportunities exist at this facility. In addition, California has
highlighted the retirements of the Redondo Beach units and the ACE
Cogeneration facility. The EPA has confirmed the retirements of these
and other units in California in the IPM version 6--Summer 2021
Reference Case database.\138\ The EPA IPM version 6--Summer 2021
Reference Case uses the National Electric Energy Data System (NEEDS) v6
database as its source for data on all existing and planned-committed
units. Units are removed from the NEEDS inventory only if a high degree
of certainty could be assigned to future implementation of the
announced future closure or retirement. The available retirement-
related information was reviewed for each unit, and the following rules
are applied to remove:
---------------------------------------------------------------------------
\138\ The ``Capacity Dropped'' and the ``Retired Through 2023''
worksheets in NEEDS list all units that are removed from the NEEDS
v6 inventory--NEEDS v6 Summer 2021 Reference Case. This data can be
found on the EPA's website at: https://www.epa.gov/airmarkets/national-electric-energy-data-system-needs-v6.
---------------------------------------------------------------------------
(i) Units that are listed as retired in the December 2020 EIA Form
860M;
(ii) Units that have a planned retirement year prior to June 30,
2023 in the December 2020 EIA Form 860M;
(iii) Units that have been cleared by a regional transmission
operator (RTO) or independent system operator (ISO) to retire before
2023, or whose RTO/ISO clearance to retire is contingent on actions
that can be completed before 2023;
(iv) Units that have committed specifically to retire before 2023
under federal or state enforcement actions or regulatory requirements;
(v) And finally, units for which a retirement announcement can be
corroborated by other available information. Units required to retire
pursuant to enforcement actions or state rules on July 1, 2023 or later
are retained in NEEDS v6.
The majority of the EGUs in California have emissions controls and
are sufficiently regulated, resulting in the lowest fossil fuel
emission rate and highest share of renewable generation among the 26
states examined at the EPA's Step 3 analysis for the proposed Federal
Implementation Plan Addressing Regional Ozone Transport for the 2015
Ozone National Ambient Air Quality Standard. 87 FR 20036, 20088. The
EPA evaluated the EGU sources within the state of California and found
there were no covered coal steam sources greater than 100 MW that would
have emissions reduction potential according to the EPA's assumed EGU
SCR retrofit mitigation technologies. The NOX emission level
for California was unchanged at 1,216 tons of NOX across the
various emission control scenarios. The EPA's Step 3 analysis,
including analysis of the emissions reduction factors from EGU sources
in the state, therefore resulted in no additional emission reductions
required to eliminate significant contribution from any EGU sources in
California.
The EPA proposes that California's Step 3 analysis was likewise
insufficient for non-EGU stationary sources. But whereas EPA is able to
conclude, based on the foregoing analysis, that additional emissions
reductions are not required from EGU sources in California, we can
reach no such conclusion with respect to other industrial sources of
emissions in the State. For non-EGUs, CARB did not complete an
evaluation of cost effective control opportunities, and instead simply
provided a cursory analysis that provided a few examples of regulations
to conclude that ``further emission controls would be unlikely to
reduce any potential impact on downwind states' air quality[.]'' \139\
CARB did not investigate additional potential emissions control
opportunities, or their costs or impacts, or attempt to analyze
whether, if applied more broadly across linked states, the emissions
reductions would constitute the elimination of significant contribution
on a regional scale.
---------------------------------------------------------------------------
\139\ Id. at A4-55.
---------------------------------------------------------------------------
The EPA acknowledges that it has previously approved California's
2008 ozone NAAQS transport SIP at Step 3 based on a relatively cursory
review of California's existing emissions control programs. See 83 FR
65093, 65094-95 (Dec. 19, 2018). That approval pre-dates the D.C.
Circuit's decision in Wisconsin v. EPA, 938 F.3d 903 (D.C. Cir. 2019),
in which the court found the EPA had not properly justified failing to
analyze emissions reduction opportunities from industrial sources
outside the power
[[Page 31460]]
sector. Id. at 918-20. At that time, the CSAPR Update had only
addressed reductions from the power sector and applied a cost threshold
of $1400 per ton. The EPA's analysis of California focused on the fact
that California's EGU fleet was very well controlled and that all
receptors for the 2008 ozone NAAQS were projected to be clean by 2023.
83 FR 65093, 65095. The EPA engaged in an extremely limited review of
other emissions control opportunities in California at non-EGU
industrial sources, despite acknowledging that these sources emitted
6.7 times as much NOX as EGUs, and 19 large stationary
sources each individually emitted over 500 tons per year. Id.
The EPA finds that good reasons exist for no longer considering
such a cursory analysis of emissions reduction opportunities beyond the
power sector to be adequate for purposes of CAA section
110(a)(2)(D)(i)(I). First, the EPA and the states are implementing the
more stringent 2015 ozone NAAQS of 70 ppb. Under that more stringent
NAAQS, our analysis at Steps 1 and 2 indicates a continuing linkage
between California's emissions and persistent air quality problems (at
least through 2026) in other states in the EPA's modeling. Further,
while California may be relatively ``well controlled'' as a state
overall on a per capita basis, the same could be said of other states
throughout the country that continue to contribute above 1 percent of
the NAAQS to at least one out of state receptor despite relatively
stringent ozone-precursor emissions control programs. In the CSAPR
Update and the Revised CSAPR Update, the EPA has found that states such
as New York and New Jersey may nonetheless be found to have additional
emissions control obligations in order to address their significant
contribution under Section 110(a)(2)(D)(i)(I).\140\ Further, the
relevance of a per capita emissions rate, which CARB cites as
relatively low for California, is not readily apparent. California is a
large and very populous state, and by CARB's own admission, total
NOX emissions from the State are second highest in the
country, behind only Texas. Finally, the EPA recognizes the critical
importance of consistency in application of good neighbor requirements
across all states, especially with respect to regional-scale pollutants
such as ozone. The EPA's regional analysis in the proposed FIP
(discussed below) indicates emissions control opportunities at non-EGUs
in California at the same stringency as EPA's Step 3 assessment of 22
other states. Therefore, for all of these reasons, the EPA does not
view the degree of analysis at Step 3 that supported approval in the
prior California transport action to be sufficient to justify approval
in this case.
---------------------------------------------------------------------------
\140\ See, e.g., ``Disapproval of Interstate Transport
Requirements for the 2008 Ozone National Ambient Air Quality
Standards; New York and New Jersey'', 86 FR 60602 (November 3,
2021).
---------------------------------------------------------------------------
The EPA notes that in the proposed FIP for California for the 2015
ozone NAAQS, we identified several potential cost-effective
NOX controls for non-EGUs in California.\141\ The EPA's non-
EGU analysis in the proposed FIP focused on several industrial sectors
and found impactful emissions reduction opportunities up to $7,500 per
ton, which the EPA proposed are needed to address 23 upwind state's
(including California's) good neighbor obligations for the 2015 ozone
NAAQS. See 87 FR 20036, 20089-90. In particular for California, the EPA
found 1,666 tons of ozone season NOX emissions reduction
available from a 2019 baseline of 14,579 tons of ozone season emissions
from the non-EGU sectors analyzed. Id. at 20090. The EPA proposed to
require these reductions in part because, in conjunction with the other
emission control strategies proposed in the FIP across the entire
region of linked upwind states, the EPA found ozone levels would
improve on average by 0.64 ppb across all impacted receptors, including
those receptors affected by California's emissions. Id. at 20096. The
EPA proposed to determine that these controls would eliminate
significant contribution and interference with maintenance for the 2015
ozone NAAQS.
---------------------------------------------------------------------------
\141\ 87 FR 20036 (April 6, 2022).
---------------------------------------------------------------------------
The EPA acknowledges that California need not have conducted a Step
3 analysis in precisely the manner as the proposed FIP, and we further
acknowledge that our FIP for California and other states is only a
proposal at this stage and is currently undergoing public comment.
Nonetheless, the proposed FIP presents an example of how a potentially
approvable Step 3 analysis could have been conducted by CARB and
highlights that cost-effective emissions reduction opportunities likely
exist in California that could address interstate transport
obligations, which CARB failed to analyze in the 2018 SIP Submittal.
CARB also attempted to support its conclusion that California does
not significantly contribute to nonattainment or maintenance in other
states in part because it suggested that emissions originating from
outside California, such as local emissions in Arizona and Colorado, as
well as international emissions, and wildfires, were the primary driver
of higher modeled design values at monitoring sites in those states
using the EPA modeling released with the January 2017 NODA and the
October 2017 memorandum.\142\
---------------------------------------------------------------------------
\142\ See California's 2018 Submittal at A4-33-A4-34, A4-44.
---------------------------------------------------------------------------
With respect to local, international, and non-anthropogenic
emissions contributions, CARB's reasoning is inapplicable to the
requirements of CAA section 110(a)(2)(D)(i)(I). The good neighbor
provision requires states and the EPA to address interstate transport
of air pollution that contributes to downwind states' ability to attain
and maintain the NAAQS. Whether emissions from other states or other
countries also contribute to the same downwind air quality issue is
irrelevant in assessing whether a downwind state has an air quality
problem, or whether an upwind state is significantly contributing to
that problem. States are not obligated under CAA section
110(a)(2)(D)(i)(I) to reduce emissions sufficient on their own to
resolve downwind receptors' nonattainment or maintenance problems.
Rather, states are obligated to eliminate their own ``significant
contribution'' or ``interference'' with the ability of other states to
attain or maintain the NAAQS.
Indeed, the D.C. Circuit in Wisconsin specifically rejected
petitioner arguments suggesting that upwind states should be excused
from good neighbor obligations on the basis that some other source of
emissions (whether international or another upwind state) could be
considered the ``but-for'' cause of downwind air quality problem. 938
F.3d 303 at 323-324. The court viewed petitioners' arguments as
essentially an argument ``that an upwind State `contributes
significantly' to downwind nonattainment only when its emissions are
the sole cause of downwind nonattainment.'' 938 F.3d 303 at 324. The
court explained that ``an upwind State can `contribute' to downwind
nonattainment even if its emissions are not the but-for cause.'' Id. at
324-325. See also Catawba County v. EPA, 571 F.3d 20, 39 (D.C. Cir.
2009) (rejecting the argument ``that `significantly contribute'
unambiguously means `strictly cause' '' because there is ``no reason
why the statute precludes EPA from determining that [an] addition of
[pollutant] into the atmosphere is significant even though a nearby
county's nonattainment problem would still persist in its absence'');
Miss. Comm'n on Envtl. Quality v. EPA, 790 F.3d 138, 163 n.12 (D.C.
Cir. 2015)
[[Page 31461]]
(observing that the argument that ``there likely would have been no
violation at all . . . if it were not for the emissions resulting from
[another source]'' is ``merely a rephrasing of the but-for causation
rule that we rejected in Catawba County.''). Therefore, a state is not
excused from eliminating its significant contribution on the basis that
international emissions also contribute some amount of pollution to the
same receptors to which the state is linked.
In conclusion, at Step 3, we propose that California was required
to analyze emissions from the sources and other emissions activity from
within the state to determine whether its contributions to
nonattainment were significant or interfered with maintenance of the
NAAQS in downwind states, and we propose to disapprove the 2018 SIP
Submittal on the separate, additional basis that it did not assess
additional emission control opportunities.
E. Evaluation of Information Provided Regarding Step 4
Step 4 of the 4-step interstate transport framework calls for
development of permanent and federally enforceable control strategies
to achieve the emissions reductions determined to be necessary at Step
3 to eliminate significant contribution to nonattainment or
interference with maintenance of the NAAQS. As mentioned previously,
California's 2018 SIP Submittal did not contain an evaluation of
additional emission control opportunities (or establish that no
additional controls are required), thus, no information was provided at
Step 4. Instead, CARB concluded that the state already has ``measures
of sufficient stringency to ensure that this State does not contribute
significantly to downwind ozone problems, whether they be nonattainment
or maintenance, in other states.'' \143\ As a result, the EPA proposes
to disapprove California's submittal on the separate, additional basis
that the State has not developed permanent and enforceable emissions
reductions necessary to meet the obligations of CAA section
110(a)(2)(D)(i)(I) for the 2015 ozone NAAQS.
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\143\ Id. at A4-58
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F. Tribal Consultation
On February 15, 2022, the EPA sent letters to the Morongo and
Pechanga tribes inviting consultation on this proposed action.\144\ On
March 2, 2022, the EPA held an informational meeting with the Morongo
Tribe. The Morongo and Pechanga tribes did not request consultation on
this Regional action. On April 7, 2022, the EPA opened a 30-day window
for federally recognized tribes to request consultation on the national
FIP proposal.
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\144\ Letter dated February 14, 2022, from Elizabeth J. Adams,
Director, Air and Radiation Division, EPA Region IX to Mark Macarro,
Chairperson, Pechanga Band of Luise[ntilde]o Indians of the Pechanga
Reservation, Re: Invitation to Consult on California's Interstate
Transport State Implementation Plan for the 2015 Ozone National
Ambient Air Quality Standards; and letter dated February 14, 2022,
from Elizabeth J. Adams, Director, Air and Radiation Division, EPA
Region IX to Charles Martin, Chairperson, Morongo Band of Mission
Indians, Re: Invitation to Consult on California's Interstate
Transport State Implementation Plan for the 2015 Ozone National
Ambient Air Quality Standards.
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G. Conclusion
Based on the EPA's evaluation of California's SIP submission, the
EPA is proposing to find that the portion of California's October 1,
2018 SIP Submittal addressing CAA section 110(a)(2)(D)(i)(I) does not
meet the State's interstate transport obligations, because it fails to
contain the necessary provisions to eliminate emissions that will
contribute significantly to nonattainment or interfere with maintenance
of the 2015 8-hour ozone NAAQS in any other state.
IV. Proposed Action
We are proposing to disapprove Enclosure 4 of California's 2018 SIP
Submittal pertaining to interstate transport of air pollution which
will significantly contribute to nonattainment or interfere with
maintenance of the 2015 8-hour ozone NAAQS in other states. Under CAA
section 110(c)(1), disapproval would establish a 2-year deadline for
the EPA to promulgate a FIP for California to address the CAA section
110(a)(2)(D)(i)(I) interstate transport requirements pertaining to
significant contribution to nonattainment, and interference with
maintenance, of the 2015 8-hour ozone NAAQS in other states, unless the
EPA approves a SIP submittal that meets these requirements. Disapproval
does not start a mandatory sanctions clock for California. The
remaining elements of the State's October 1, 2018 SIP Submittal are not
addressed in this action and have been acted on in a separate
rulemaking.\145\
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\145\ 86 FR 16533 (March 30, 2021).
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V. Statutory and Executive Order Reviews
A. Executive Order 12866: Regulatory Planning and Review and Executive
Order 13563: Improving Regulation and Regulatory Review
This action is not a significant regulatory action and was
therefore not submitted to the Office of Management and Budget (OMB)
for review.
B. Paperwork Reduction Act (PRA)
This action does not impose an information collection burden under
the PRA, because this proposed SIP disapproval, if finalized, will not
in-and-of itself create any new information collection burdens, but
will simply disapprove certain State requirements for inclusion in the
SIP.
C. Regulatory Flexibility Act (RFA)
I certify that this action will not have a significant economic
impact on a substantial number of small entities under the RFA. This
action will not impose any requirements on small entities. This
proposed SIP disapproval, if finalized, will not in-and-of itself
create any new requirements but will simply disapprove certain State
requirements for inclusion in the SIP.
D. Unfunded Mandates Reform Act (UMRA)
This action does not contain any unfunded mandate as described in
UMRA, 2 U.S.C. 1531-1538, and does not significantly or uniquely affect
small governments. This action proposes to disapprove pre-existing
requirements under State or local law, and imposes no new requirements.
Accordingly, no additional costs to State, local, or tribal
governments, or to the private sector, result from this action.
E. Executive Order 13132: Federalism
This action does not have federalism implications. It will not have
substantial direct effects on the states, on the relationship between
the national government and the states, or on the distribution of power
and responsibilities among the various levels of government.
F. Executive Order 13175: Coordination With Indian Tribal Governments
This action does not have tribal implications, as specified in
Executive Order 13175, because the SIP revision that the EPA is
proposing to disapprove would not 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 and will not impose substantial direct
costs on tribal governments or preempt tribal law. Thus, Executive
Order 13175 does not apply to this action.
[[Page 31462]]
G. Executive Order 13045: Protection of Children From Environmental
Health Risks and Safety Risks
The EPA interprets Executive Order 13045 as applying only to those
regulatory actions that concern environmental health or safety risks
that the EPA has reason to believe may disproportionately affect
children, per the definition of ``covered regulatory action'' in
section 2-202 of the Executive Order. This action is not subject to
Executive Order 13045 because this proposed SIP disapproval, if
finalized, will not in-and-of itself create any new regulations, but
will simply disapprove certain State requirements for inclusion in the
SIP.
H. Executive Order 13211: Actions That Significantly Affect Energy
Supply, Distribution, or Use
This action is not subject to Executive Order 13211, because it is
not a significant regulatory action under Executive Order 12866.
I. National Technology Transfer and Advancement Act (NTTAA)
Section 12(d) of the NTTAA directs the EPA to use voluntary
consensus standards in its regulatory activities unless to do so would
be inconsistent with applicable law or otherwise impractical. The EPA
believes that this action is not subject to the requirements of section
12(d) of the NTTAA because application of those requirements would be
inconsistent with the CAA.
J. Executive Order 12898: Federal Actions To Address Environmental
Justice in Minority Populations and Low-Income Population
The EPA believes the human health or environmental risk addressed
by this action will not have potential disproportionately high and
adverse human health or environmental effects on minority, low-income
or indigenous populations. This action merely proposes to disapprove a
SIP submission as not meeting the CAA.
K. CAA Section 307(b)(1)
Section 307(b)(1) of the CAA governs judicial review of final
actions by the EPA. This section provides, in part, that petitions for
review must be filed in the D.C. Circuit: (i) When the agency action
consists of ``nationally applicable regulations promulgated, or final
actions taken, by the Administrator,'' or (ii) when such action is
locally or regionally applicable, if ``such action is based on a
determination of nationwide scope or effect and if in taking such
action the Administrator finds and publishes that such action is based
on such a determination.'' For locally or regionally applicable final
actions, the CAA reserves to the EPA complete discretion whether to
invoke the exception in (ii).\146\
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\146\ In deciding whether to invoke the exception by making and
publishing a finding that an action is based on a determination of
nationwide scope or effect, the Administrator takes into account a
number of policy considerations, including his judgment balancing
the benefit of obtaining the D.C. Circuit's authoritative
centralized review versus allowing development of the issue in other
contexts and the best use of agency resources.
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If the EPA takes final action on this proposed rulemaking, the
Administrator intends to exercise the complete discretion afforded to
him under the CAA to make and publish a finding that the final action
(to the extent a court finds the action to be locally or regionally
applicable) is based on a determination of ``nationwide scope or
effect'' within the meaning of CAA section 307(b)(1). Through this
rulemaking action (in conjunction with a series of related actions on
other SIP submissions for the same CAA obligations), the EPA interprets
and applies section 110(a)(2)(d)(i)(I) of the CAA for the 2015 ozone
NAAQS based on a common core of nationwide policy judgments and
technical analysis concerning the interstate transport of pollutants
throughout the continental U.S. In particular, the EPA is applying here
(and in other proposed actions related to the same obligations) the
same, nationally consistent 4-step framework for assessing good
neighbor obligations for the 2015 ozone NAAQS. The EPA relies on a
single set of updated, 2016-base year photochemical grid modeling
results of the year 2023 as the primary basis for its assessment of air
quality conditions and contributions at steps 1 and 2 of that
framework. Further, the EPA proposes to determine and apply a set of
nationally consistent policy judgments to apply the 4-step framework.
The EPA has selected a nationally uniform analytic year (2023) for this
analysis and is applying a nationally uniform approach to nonattainment
and maintenance receptors and a nationally uniform approach to
contribution threshold analysis.\147\ For these reasons, the
Administrator intends, if this proposed action is finalized, to
exercise the complete discretion afforded to him under the CAA to make
and publish a finding that this action is based on one or more
determinations of nationwide scope or effect for purposes of CAA
section 307(b)(1).\148\
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\147\ A finding of nationwide scope or effect is also
appropriate for actions that cover states in multiple judicial
circuits. In the report on the 1977 Amendments that revised section
307(b)(1) of the CAA, Congress noted that the Administrator's
determination that the ``nationwide scope or effect'' exception
applies would be appropriate for any action that has a scope or
effect beyond a single judicial circuit. See H.R. Rep. No. 95-294 at
323, 324, reprinted in 1977 U.S.C.C.A.N. 1402-03.
\148\ The EPA may take a consolidated, single final action on
all of the proposed SIP disapproval actions with respect to
obligations under CAA section 110(a)(2)(D)(i)(I) for the 2015 ozone
NAAQS. Should the EPA take a single final action on all such
disapprovals, this action would be nationally applicable, and the
EPA would also anticipate, in the alternative, making and publishing
a finding that such final action is based on a determination of
nationwide scope or effect.
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List of Subjects in 40 CFR Part 52
Environmental protection, Air pollution control, Incorporation by
reference, Ozone.
Authority: 42 U.S.C. 7401 et seq.
Dated: May 15, 2022.
Martha Guzman Aceves,
Regional Administrator, Region IX.
[FR Doc. 2022-11150 Filed 5-23-22; 8:45 am]
BILLING CODE 6560-50-P