Document ID: EPA-R04-OAR-2021-0841-0029
Agency: epa
Document Type: Proposed Rule
Title: Air Quality State Implementation Plans; Approvals and Promulgations: Alabama; Interstate Transport Requirements for the 2015 8-Hour Ozone National Ambient Air Quality Standards
Posted Date: 2022-10-25T04:00Z

[Federal Register Volume 87, Number 205 (Tuesday, October 25, 2022)]
[Proposed Rules]
[Pages 64412-64427]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2022-22892]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R04-OAR-2021-0841; EPA-HQ-OAR-2021-0663; FRL-10291-01-R4]

Air Plan Disapproval; AL; Interstate Transport Requirements for 
the 2015 8-Hour Ozone National Ambient Air Quality Standards

AGENCY: Environmental Protection Agency (EPA).

[[Page 64413]]

ACTION: Proposed rule.

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SUMMARY: Pursuant to the Federal Clean Air Act (CAA or the Act), the 
Environmental Protection Agency (EPA or Agency) is proposing to 
disapprove the State Implementation Plan (SIP) submittal from Alabama 
dated June 21, 2022, regarding the interstate transport requirements 
for the 2015 8-hour ozone national ambient air quality standards (NAAQS 
or standard). The ``Good Neighbor'' or ``Interstate Transport'' 
provision of the Act requires that each State's implementation plan 
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. If EPA finalizes this disapproval, the Agency will 
continue to be subject to an obligation to promulgate a Federal 
Implementation Plan (FIP) for Alabama to address the relevant 
interstate transport requirements, which was triggered by a finding of 
failure to submit published on June 22, 2022. Disapproval does not 
start a mandatory sanctions clock.

DATES: Written comments must be received on or before November 25, 
2022.

ADDRESSES: You may submit comments, identified by Docket No. EPA-R04-
OAR-2021-0841, through the Federal eRulemaking Portal at https://www.regulations.gov following the online instructions for submitting 
comments.
    Instructions: All submissions received must include the Docket No. 
EPA-R04-OAR-2021-0841 for this rulemaking. Comments received may be 
posted without change to https://www.regulations.gov/, including any 
personal information provided. For detailed instructions on submitting 
comments and additional information on the rulemaking process, see the 
``Public Participation'' heading of the SUPPLEMENTARY INFORMATION 
section of this document. The EPA Docket Office can be contacted at 
(202) 566-1744, and is located at EPA Docket Center Reading Room, WJC 
West Building, Room 3334, 1301 Constitution Avenue NW, Washington, DC 
20004. For further information on EPA Docket Center services and the 
current hours of operation at the EPA Docket Center, please visit us 
online at https://www.epa.gov/dockets.

FOR FURTHER INFORMATION CONTACT: Evan Adams of the Air Regulatory 
Management Section, Air Planning and Implementation Branch, Air and 
Radiation Division, U.S. Environmental Protection Agency, Region 4, 61 
Forsyth Street SW, Atlanta, Georgia 30303-8960. Mr. Adams can be 
reached by telephone at (404) 562-9009, or via electronic mail at 
[email protected].

SUPPLEMENTARY INFORMATION: Public Participation: Submit your comments, 
identified by Docket No. EPA-R04-OAR-2021-0841, at https://www.regulations.gov. Once submitted, comments cannot be edited or 
removed from the docket. EPA may publish any comment received to its 
public docket. Do not submit to EPA's docket at https://www.regulations.gov any information 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. 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-R04-OAR-2021-0841 
and EPA-HQ-OAR-2021-0663. Docket No. EPA-R04-OAR-2021-0841 contains 
information specific to Alabama, Mississippi, Tennessee, and 
Kentucky,\1\ including this 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 which are being used to support this 
action. All comments regarding information in either of these dockets 
are to be made in Docket No. EPA-R04-OAR-2021-0841. 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.
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    \1\ EPA previously proposed action related to another Alabama 
SIP submission addressing the 2015 ozone interstate transport 
requirements in a notice of proposed rulemaking that included 
Mississippi's and Tennessee's SIP submissions addressing these same 
requirements. EPA is using that same docket for the proposed action 
related to Alabama's June 21, 2022, submittal addressing the 2015 
ozone interstate transport requirements. EPA is not reopening for 
public comment the notice of proposed rulemaking published in the 
Federal Register at 87 FR 9545 on February 22, 2022.
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    The indices to Docket No. EPA-R04-OAR-2021-0841 and Docket No. EPA-
R04-OAR-2021-0663 are available electronically at www.regulations.gov. 
While all documents in each docket are listed in their respective 
index, some information may not be publicly available due to docket 
file size restrictions or content (e.g., CBI).

Table of Contents

I. Background
    A. Description of Statutory Background
    B. Description of EPA's Four Step Interstate Transport 
Regulatory Process
    C. Background on EPA's Ozone Transport Modeling Information
    D. EPA's Approach to Evaluating Interstate Transport SIPs for 
the 2015 8-Hour Ozone NAAQS
II. Summary of Alabama's 2015 8-Hour Ozone Transport SIP Submissions
    A. Prior Submissions
    B. Current Submission
III. EPA's Evaluation of Alabama's 2015 Ozone Interstate Transport 
SIP Submission
    A. Results of EPA's Step 1 and Step 2 Modeling and Findings for 
Alabama
    B. Evaluation of Information Provided by Alabama Regarding Step 
1
    C. Evaluation of Information Provided by Alabama Regarding Step 
2
    D. Evaluation of Information Provided by Alabama Regarding Step 
3
    E. Evaluation of Information Provided by Alabama Regarding Step 
4
IV. Conclusion for Alabama
V. Proposed Action
VI. Statutory and Executive Order Reviews

I. Background

    The following provides background for EPA's proposed action related 
to the interstate transport requirements for the 2015 8-hour ozone 
NAAQS for Alabama.

A. Description of Statutory Background

    On October 1, 2015, 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).\2\ 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).\3\ One of these 
applicable

[[Page 64414]]

requirements is found in CAA section 110(a)(2)(D)(i)(I), otherwise 
known as the ``good neighbor'' or ``interstate transport'' 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). A SIP 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). 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).\4\
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    \2\ 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.
    \3\ 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.
    \4\ See North Carolina v. EPA, 531 F.3d 896, 909-11 (D.C. Cir. 
2008).
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B. Description of EPA's Four Step Interstate Transport Regulatory 
Process

    EPA is using the 4-step interstate transport framework (or 4-step 
framework) to evaluate the SIP submittal from the Alabama Department of 
Environmental Management (ADEM or Alabama) addressing the interstate 
transport provision for the 2015 8-hour ozone NAAQS. 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,\5\ and the 
Cross-State Air Pollution Rule Update (CSAPR Update) \6\ and the 
Revised CSAPR Update, both of which addressed the 2008 ozone NAAQS.\7\
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    \5\ See Federal Implementation Plans: Interstate Transport of 
Fine Particulate Matter and Ozone and Correction of SIP Approvals, 
76 FR 48208 (August 8, 2011).
    \6\ Cross-State Air Pollution Rule Update for the 2008 Ozone 
NAAQS, 81 FR 74504 (October 26, 2016).
    \7\ In 2019, the United States Court of Appeals for the District 
of Columbia Circuit (D.C. Circuit) 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 (D.C. Cir. 2019).
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    Through the development and implementation of the CSAPR rulemakings 
and prior regional rulemakings pursuant to the interstate transport 
provision,\8\ EPA, working in partnership with states, developed the 
following 4-step interstate transport 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 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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    \8\ 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 EPA's Ozone Transport Modeling Information

    In general, EPA has performed nationwide air quality modeling to 
project ozone design values which are used in combination with measured 
data to identify nonattainment and maintenance receptors. To quantify 
the contribution of emissions from specific upwind states on 2023 ozone 
design values for the identified downwind nonattainment and maintenance 
receptors, EPA performed nationwide, State-level ozone source 
apportionment modeling for 2023. 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 upwind states.
    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, EPA published a notice of data availability 
(NODA) in which the Agency 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, 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, EPA released a memorandum 
(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, EPA 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\ EPA 
subsequently issued

[[Page 64415]]

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\ See 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 (``October 2017 memorandum''), 
available in Docket ID No. EPA-HQ-OAR-2021-0663 or at https://www.epa.gov/interstate-air-pollution-transport/interstate-air-pollution-transport-memos-and-notices.
    \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 or at https://www.epa.gov/interstate-air-pollution-transport/interstate-air-pollution-transport-memos-and-notices.
    \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 or at https://www.epa.gov/sites/default/files/2018-10/documents/maintenance_receptors_flexibility_memo.pdf.
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    Since the release of the modeling data shared in the March 2018 
memorandum, 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 EPA, MJOs, and states to develop a new, more recent 
emissions platform for use by EPA and states in regulatory modeling as 
an improvement over the dated 2011-based platform that EPA had used to 
project ozone design values and contribution data provided in the 2017 
and 2018 memoranda. 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, EPA 
released and accepted public comment on 2023 modeling that used the 
2016v1 emissions platform.\16\ Although the Revised CSAPR 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 8-hour 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 
Docket ID No. EPA-HQ-OAR-2021-0663.
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    Following the Revised CSAPR Update final rule, EPA made further 
updates to the 2016 emissions platform to include mobile emissions from 
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) included in the 
docket for this proposed rulemaking.\19\ EPA performed air quality 
modeling of the 2016v2 emissions using the most recent public release 
version of the Comprehensive Air Quality Modeling with Extensions 
(CAMx) photochemical modeling, version 7.10.\20\ EPA proposes to 
primarily rely on modeling based on the updated and newly available 
2016v2 emissions platform in evaluating these submissions with respect 
to Steps 1 and 2 of the 4-step interstate transport framework. By using 
the updated modeling results, EPA is using the most recently available 
and technically appropriate information for this proposed rulemaking. 
Section III of this document and the Air Quality Modeling TSD for 2015 
Ozone NAAQS Transport SIP Proposed Actions included in Docket No. EPA-
HQ-OAR-2021-0663 contain additional detail on the modeling performed 
using the 2016v2 emissions modeling.
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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 Docket ID No. EPA-HQ-OAR-2021-
0663.
    \20\ Ramboll Environment and Health, January 2021, www.camx.com.
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    In this document, EPA is accepting public comment on this updated 
2023 modeling, which uses the 2016v2 emissions platform. Comments on 
EPA's air quality modeling should be submitted in Docket No. EPA-R04-
OAR-2021-0841. Comments are not being accepted in Docket No. EPA-HQ-
OAR-2021-0663.
    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 of this document, EPA evaluates how Alabama 
used air quality modeling information in their submission.

D. EPA's Approach to Evaluating Interstate Transport SIPs for the 2015 
8-Hour Ozone NAAQS

    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 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, 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. 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, 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 concepts as may have been identified or suggested in the 
past, EPA will evaluate whether the State adequately justified the 
technical and legal basis for doing so.
    EPA notes that certain potential 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 8-hour ozone NAAQS. Attachment A to the March 
2018 memorandum identified a ``Preliminary List of Potential 
Flexibilities'' that could potentially inform SIP development.\21\ 
However, 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 EPA sought

[[Page 64416]]

``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, 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 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 EPA must implement the interstate 
transport provision in a manner ``consistent with the provisions of 
[title I of the CAA.]'' See 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). See 938 F.3d 303, 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 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 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). 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 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\ 
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\ EPA notes that the court in Maryland did not have occasion 
to evaluate circumstances in which 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 August 3, 2018).
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    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 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, EPA must act on SIP submittals using the 
information available at the time it takes such action. In this 
circumstance, 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 23054, 23074, April 30, 2021; see also Wisconsin, 938 F.3d at 
322. Consequently, in this proposal EPA will use the analytical year of 
2023 to evaluate Alabama'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, EPA identifies monitoring sites that are projected to 
have problems attaining and/or maintaining the NAAQS in the 2023 
analytic year. Where 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 EPA's 4-step interstate 
transport framework. For sites that are identified as a nonattainment 
or maintenance receptor in 2023, EPA proceeds to the next step of the 
4-step interstate transport framework by identifying the upwind state's 
contribution to those receptors.
    EPA's approach to identifying ozone nonattainment and maintenance 
receptors in this action is consistent with the approach used in 
previous transport rulemakings. 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 896, 910-11 (D.C. Cir. 
2008) (holding that 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, 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 EPA defined nonattainment receptors as those areas 
that both currently measure nonattainment and that EPA projects

[[Page 64417]]

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 
at 25241, 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).
---------------------------------------------------------------------------

    In addition, in this proposal, EPA identifies a receptor to be a 
``maintenance'' receptor for purposes of defining interference with 
maintenance, consistent with the method used in 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, 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. 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). EPA also recognizes that 
previously experienced meteorological conditions (e.g., dominant wind 
direction, temperatures, 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). The 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, 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, 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, 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), the upwind state is not 
``linked'' to a downwind air quality problem, and 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).
    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 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. EPA 
continues to find 1 percent to be an appropriate threshold. For ozone, 
as EPA found in CAIR, CSAPR, and the 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. EPA's analysis shows that much of the ozone 
transport problem being analyzed in this proposed rulemaking is 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 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 at 74518, October 26, 2016; see 
also 86 FR at 23085, April 30, 2021 (reviewing and explaining rationale 
from CSAPR, 76 FR at 48237-38, August 8, 2011, for selection of 1 
percent threshold).
    The following describes EPA's experience with alternative Step 2 
thresholds. 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, 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.
    EPA here shares further evaluation of its experience since the 
issuance of the August 2018 memorandum regarding use of alternative 
thresholds at Step 2. This experience leads the Agency to now believe 
it may not be appropriate to continue to attempt to recognize 
alternative contribution thresholds at Step 2. The August 2018 
memorandum stated that ``it may be reasonable and appropriate'' for 
states to rely on an alternative threshold of 1 ppb at Step 2.\30\ (The 
memorandum also indicated that any higher alternative threshold, such 
as 2 ppb, would likely not be appropriate.) However, EPA also provided 
that ``air agencies should consider whether the recommendations in this 
guidance are appropriate for each situation.'' Following receipt and 
review of 49 good neighbor SIP submittals for the 2015 8-hour ozone 
NAAQS, EPA's experience has been that nearly every State that attempted 
to rely on a 1 ppb threshold did not provide sufficient

[[Page 64418]]

information and analysis to support a determination that an alternative 
threshold was reasonable or appropriate for that State.
---------------------------------------------------------------------------

    \30\ See August 2018 memorandum at 4.
---------------------------------------------------------------------------

    For instance, in nearly all submittals, the states did not provide 
EPA with analysis specific to their State or the receptors to which its 
emissions are potentially linked. In one case, the proposed approval of 
Iowa's SIP submittal, EPA expended its own resources to attempt to 
supplement the information submitted by the State, in order to more 
thoroughly evaluate the state-specific circumstances that could support 
approval.\31\ It was at EPA's sole discretion to perform this analysis 
in support of the State's submittal, and the Agency is not obligated to 
conduct supplemental analysis to fill the gaps whenever it believes a 
State's analysis is insufficient. The Agency no longer intends to 
undertake supplemental analysis of SIP submittals with respect to 
alternative thresholds at Step 2 for purposes of the 2015 8-hour ozone 
NAAQS.
---------------------------------------------------------------------------

    \31\ Air Plan Approval; Iowa; Infrastructure State 
Implementation Plan Requirements for the 2015 Ozone National Ambient 
Air Quality Standard, 85 FR 12232 (March 2, 2020). The Agency 
received adverse comment on this proposed approval and has 
subsequently formally withdrawn the proposed approval. See 87 FR 
9477 (February 22, 2022).
---------------------------------------------------------------------------

    Furthermore, EPA's experience since 2018 is that allowing for 
alternative Step 2 thresholds may be impractical or otherwise 
inadvisable for a number of additional policy reasons. For a regional 
air pollutant such as ozone, consistency in requirements and 
expectations across all states is essential. Based on its review of 
submittals to-date and after further consideration of the policy 
implications of attempting to recognize an alternative Step 2 threshold 
for certain states, the Agency now believes the attempted use of 
different thresholds at Step 2 with respect to the 2015 8-hour ozone 
NAAQS raises substantial policy consistency and practical 
implementation concerns.\32\ The availability of different thresholds 
at Step 2 has the potential to result in inconsistent application of 
good neighbor obligations based solely on the strength of a State's 
implementation plan submittal at Step 2 of the 4-step interstate 
transport framework. From the perspective of ensuring effective 
regional implementation of good neighbor obligations, the more 
important analysis is the evaluation of the emissions reductions 
needed, if any, to address a State's significant contribution after 
consideration of a multifactor analysis at Step 3, including a detailed 
evaluation that considers air quality factors and cost. Where 
alternative thresholds for purposes of Step 2 may be ``similar'' in 
terms of capturing the relative amount of upwind contribution (as 
described in the August 2018 memorandum), nonetheless, use of an 
alternative threshold would allow certain states to avoid further 
evaluation of potential emission controls while other states must 
proceed to a Step 3 analysis. This can create significant equity and 
consistency problems among states.
---------------------------------------------------------------------------

    \32\ EPA notes that Congress has placed on EPA a general 
obligation to ensure the requirements of the CAA are implemented 
consistently across states and regions. See CAA section 301(a)(2). 
Where the management and regulation of interstate pollution levels 
spanning many states is at stake, consistency in application of CAA 
requirements is paramount.
---------------------------------------------------------------------------

    Further, it is not clear that national ozone transport policy is 
best served by allowing for less stringent thresholds at Step 2. EPA 
recognized in the August 2018 memorandum that there was some similarity 
in the amount of total upwind contribution captured (on a nationwide 
basis) between 1 percent and 1 ppb. However, EPA notes that while this 
may be true in some sense, that is hardly a compelling basis to move to 
a 1 ppb threshold. Indeed, the 1 ppb threshold has the disadvantage of 
losing a certain amount of total upwind contribution for further 
evaluation at Step 3 (e.g., roughly 7 percent of total upwind state 
contribution was lost according to the modeling underlying the August 
2018 memorandum; \33\ in EPA's updated modeling, the amount lost is 5 
percent). Considering the core statutory objective of ensuring 
elimination of all significant contribution to nonattainment or 
interference of the NAAQS in other states and the broad, regional 
nature of the collective contribution problem with respect to ozone, 
there does not appear to be a compelling policy imperative in allowing 
some states to use a 1 ppb threshold while others rely on a 1 percent 
of the NAAQS threshold.
---------------------------------------------------------------------------

    \33\ See August 2018 memorandum at 4.
---------------------------------------------------------------------------

    Consistency with past interstate transport actions such as CSAPR, 
and the CSAPR Update and Revised CSAPR Update rulemakings (which used a 
Step 2 threshold of 1 percent of the NAAQS for two less stringent ozone 
NAAQS), is also important. Continuing to use a 1 percent of NAAQS 
approach ensures that as the NAAQS are revised and made more stringent, 
an appropriate increase in stringency at Step 2 occurs, so as to ensure 
an appropriately larger amount of total upwind-state contribution is 
captured for purposes of fully addressing interstate transport. See 76 
FR 48208, 48237-38, August 8, 2011.
    Therefore, notwithstanding the August 2018 memorandum's recognition 
of the potential viability of alternative Step 2 thresholds, and in 
particular, a potentially applicable 1 ppb threshold, EPA's experience 
since the issuance of that memorandum has revealed substantial 
programmatic and policy difficulties in attempting to implement this 
approach. As discussed further below, the basis for disapproval of 
Alabama's SIP submission with respect to the Step 2 analysis is, in the 
Agency's view, warranted even under the terms of the August 2018 
memorandum.
4. Step 3 of the 4-Step Interstate Transport Framework
    Consistent with 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. 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 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 EPA has not prescribed a particular method for this assessment, 
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

[[Page 64419]]

additional emissions controls should be required.\34\
---------------------------------------------------------------------------

    \34\ 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, October 26, 2016; CSAPR, 76 FR 48208, 
48246-63, August 8, 2011; CAIR, 70 FR 25162, 25195-229; or the NOx 
SIP Call, 63 FR 57356, 57399-405, October 27, 1998. See also the 
Revised CSAPR Update, 86 FR 23054, 23086-23116, April 30, 2021. 
Consistently across these rulemakings, 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 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 
implementation plan 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 section 110(a)(2)(A); 
Committee for a Better Arvin v. EPA, 786 F.3d 1169, 1175-76 (9th Cir. 
2015) (holding that measures relied on by a State to meet CAA 
requirements must be included in the SIP).

II. Summary of Alabama's 2015 8-Hour Ozone Transport SIP Submissions

    The following section provides information related to Alabama's 
June 21, 2022, SIP submission addressing the interstate transport 
requirements for the 2015 8-hour ozone NAAQS, as well as information 
related to previous submittals for the 2015 8-hour ozone NAAQS.

A. Prior Submissions

    On August 20, 2018, Alabama submitted multiple SIP revisions under 
one cover letter, including an interstate transport SIP revision for 
the 2015 8-hour ozone NAAQS which relied on modeling released with the 
March 2018 memorandum. EPA initially proposed approval of Alabama's 
interstate transport SIP revision for the 2015 8-hour ozone NAAQS, 
based on the modeling provided in the March 2018 memorandum. See 84 FR 
71854, 71859 (December 30, 2019). When EPA completed updating the 
modeling of 2023 in 2020, using a 2016-based emissions modeling 
platform (2016v1), it became evident that Alabama was projected to be 
linked above 1 percent of the NAAQS to downwind nonattainment and 
maintenance receptors (see footnote 47 of this document).
    As a result, EPA deferred acting on Alabama's interstate transport 
SIP submittal when EPA published a supplemental proposal in 2021 to 
approve four other southeastern states' good neighbor SIP submissions 
using the updated 2023 modeling. See 86 FR 37942, 37943 (July 19, 
2021). The next update to the 2023 modeling used an updated 2016-based 
emissions modeling platform (2016v2), and it confirms the prior 2016-
based modeling of 2023 in that it continues to show Alabama is linked 
to at least one downwind nonattainment or maintenance receptor above 1 
percent of the NAAQS.
    Subsequently, EPA proposed to disapprove Alabama's August 20, 2018, 
interstate transport SIP submission on February 22, 2022, based in part 
on the updated modeling using the 2016v2 emissions modeling platform, 
discussed in Section I.C. of this document. See 87 FR 9545, 9562. 
Additionally, EPA withdrew its 2019 proposed approval on Alabama's 
August 20, 2018, interstate transport SIP revision as published on 
December 30, 2019. See 84 FR 71854.
    Subsequently, on April 21, 2022, ADEM withdrew the August 20, 2018, 
submission that EPA had proposed to disapprove.\35\ On the same day, 
April 21, 2022, ADEM provided a replacement submission for its August 
20, 2018, submission addressing the interstate requirements for the 
2015 ozone standards. Based on EPA's review of that new submission and 
the completeness criteria for SIPs (40 CFR part 51, Appendix V), EPA 
determined Alabama's April 21, 2022, submission was incomplete and 
provided that determination to Alabama in a letter dated June 14, 
2022.\36\ On June 15, 2022, EPA signed a document (published in the 
Federal Register on June 22, 2022), finding that the State failed to 
submit a complete submission addressing the 2015 ozone interstate 
transport requirements through the transmission of Alabama's April 21, 
2022, submittal. See 87 FR 37235.
---------------------------------------------------------------------------

    \35\ ADEM's April 21, 2022, withdrawal letter is provided in 
Docket ID No. EPA-R04-OAR-2021-0841.
    \36\ See EPA's June 14, 2022, incompleteness letter to ADEM in 
Docket ID No. EPA-R04-OAR-2021-0841.
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B. Current Submission

    On June 21, 2022, Alabama submitted a SIP revision addressing the 
CAA section 110(a)(2)(D)(i)(I) good neighbor interstate transport 
requirements for the 2015 8-hour ozone NAAQS. The SIP submission 
purported to address the issues identified in the EPA's June 15, 2022, 
incompleteness letter. The June 21, 2022, SIP submission provides 
Alabama's evaluation of its impact on downwind states and concludes 
that emissions from the State will not significantly contribute to 
nonattainment or interfere with maintenance of the 2015 8-hour ozone 
NAAQS in other states in 2023.
    Alabama's June 21, 2022, submittal identifies existing SIP-approved 
regulations and Federal programs \37\ that regulate ozone precursor 
emissions from sources in the State, including the CSAPR trading 
programs, which, according to Alabama, are the reason for the decline 
of ozone precursor emissions in the State.\38\ Alabama's submission 
acknowledges that CSAPR does not address interstate transport for the 
2015 ozone standard but does provide residual NOX emission 
reductions and notes that the CSAPR NOX ozone season trading 
programs were adopted into the Alabama SIP on August 31, 2016, and 
October 6, 2017.\39\ Alabama notes that the implementation of the 
existing SIP-approved regulations and Federal programs provide for a 
decline in ozone precursor emissions in the State. Alabama also states 
there are no nonattainment or maintenance areas in Alabama and that 
ozone precursor emissions would continue to decline in the State.
---------------------------------------------------------------------------

    \37\ Alabama's submission cites the following SIP approved 
regulations: Administrative Code Rule 335-3-6, ``Control of Organic 
Emissions'', 335-3-8, ``Control of Nitrogen Oxides Emissions'', 335-
3-14-.01, ``General Provisions'', 335-3-14-.02, ``Permit 
Procedures'', 335-3-14-.03, ``Standards for Granting Permits'', 335-
3-14-.04, ``Air Permits Authorizing Construction in Clean Air Areas 
[Prevention of Significant Deterioration Permitting (PSD)]'' and 
335-3-14-.05, ``Air Permits Authorizing Construction in or Near 
Nonattainment Areas.'' Alabama's Submission cites the following 
Federal Rules: EPA's Tier 1 and 2 mobile source rules, EPA's nonroad 
Diesel Rule, EPA's 2007 Heavy-duty Highway Rule, New Source 
Performance Standards, National Emission Standards for Hazardous Air 
Pollutants, and CSAPR.
    \38\ Alabama's SIP references CSAPR, which covers the 
NOX ozone season trading program established in EPA's 
2011 CSAPR, 76 FR 48208 (August 8, 2011). In addition, Alabama's 
submittal includes a reference to the SIP-approved rules that 
adopted the CSAPR Update, 81 FR 74504 (October 26, 2016). See 82 FR 
46674 (October 6, 2017).
    \39\ See 81 FR 59869 (August 31, 2016), 82 FR 46674 (October 6, 
2017) (adopting Alabama Administrative Code Rule 335-3-8, ''Control 
of Nitrogen Oxides Emissions'' and adopting revisions to Rule 335-3-
8 into the SIP).

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[[Page 64420]]

    The State's submission also includes a weight of evidence (WOE) 
analysis \40\ that evaluates data related to Alabama in EPA's 2016v2 
emissions modeling platform.\41\ The WOE analysis begins by 
acknowledging that EPA's January 2022 2016v2 modeling platform results 
indicate that Alabama is predicted to contribute above 0.70 ppb to one 
predicted nonattainment monitor and one predicted maintenance monitor. 
The WOE analysis then evaluates meteorological influence, Alabama 
emission sources, model performance, and the ``significance threshold'' 
(in fact, what EPA would refer to as the ``contribution threshold''). 
EPA summarizes the State's qualitative and quantitative analysis below.
---------------------------------------------------------------------------

    \40\ See Attachment A of Alabama's June 21, 2022, 2015 ozone 
transport SIP submission provided in Docket ID No. EPA-R04-OAR-2021-
0841.
    \41\ EPA notes that Alabama's SIP submission is not organized 
around EPA's 4-Step Framework for assessing good neighbor 
obligations, but EPA summarizes the submission using that framework 
for clarity here.
---------------------------------------------------------------------------

    Based on this information, Alabama's submission states that 
emissions from Alabama do not contribute above 1 ppb of the 2015 8-hour 
ozone NAAQS at any projected nonattainment or maintenance receptors at 
Step 2 of the 4-Step Framework (using EPA's approach to defining such 
receptors). ADEM then concludes that emissions from Alabama sources 
will not significantly contribute to nonattainment or interfere with 
maintenance of the 2015 8-hour ozone NAAQS in any other State.
1. Alabama's Weight of Evidence Analysis
    Alabama's June 21, 2022, submittal includes a WOE analysis of the 
data related to Alabama in EPA's 2016v2 modeling platform. The analysis 
begins by acknowledging that EPA's modeling shows sources in Alabama 
contributing greater than one percent of the NAAQS to downwind 
nonattainment and maintenance receptors at Harris County and Denton 
County, Texas, respectively, in 2023. Alabama states that EPA's 2016v2 
modeling does not establish that Alabama is linked to any receptors in 
2023, and the modeling does not identify any downwind linkages greater 
than one percent in 2026. Alabama states that based on an assessment of 
all available information and weighing the data by considering the 
relevance and quality of the information through both qualitative and 
quantitative analyses, emissions from Alabama do not significantly 
contribute to downwind nonattainment or maintenance receptors for the 
2015 8-hr ozone NAAQS. Below is a summary of Alabama's WOE analysis.
a. Identifying Maintenance Receptors--Step 1 of 4-Step Framework
    Alabama's analysis suggests that determining significance should be 
different for nonattainment and maintenance receptors and cites EPA's 
October 2018 memorandum, which discusses alternative methods to 
identifying maintenance receptors. Alabama indicates that an approach 
for identification of maintenance receptors could include relying on 
the continued decline of emissions in an area out to the attainment 
date of the receptor. Applying this approach, Alabama asserts that it 
should be excluded as a significant contributor to the Denton County, 
Texas receptor because the modeled average concentration is 70.4 ppb 
and maximum concentration is 72.2 ppb in 2023, and there will be 
continuing emissions reductions at Alabama point sources, which Alabama 
asserts are the only emissions it can reasonably control.
b. Alternative Significant Contribution Threshold--Step 2 of 4-Step 
Framework
    Alabama points to EPA's 2018 March and August 2018 memoranda and 
states that the two documents provide for flexibility in determining 
significance and support Alabama's argument establishing 1 ppb as a 
sufficient threshold. Alabama goes on to assert that there is precedent 
for setting a 1 ppb significance threshold for ozone in the PSD 
permitting program and that since the purpose of the PSD permitting 
program is to show compliance with the NAAQS, 1 ppb should be 
consistent for determining future year significance against the ozone 
NAAQS.
c. Modeling Performance--Step 2 of 4-Step Framework
    Alabama asserts that a threshold of 0.71 ppb is within the margin 
of error for the model. Alabama goes on to reference EPA's TSD for the 
2016v2 platform modeling and suggests that, considering that there is 
bias and error in the modeling (ranging from +/-2.9 to 6.1 ppb in the 
southeast and +/-7.8 to 9.1 ppb in the south, according to Alabama), 
the 0.70 ppb threshold could not accurately represent ``with true 
accuracy'' impacts hundreds of miles from a downwind receptor.
d. Meteorological Influence and Back Trajectories--Step 2 of 4-Step 
Framework
    Alabama's WOE analysis includes Hybrid Single Particle Lagrangian 
Integrated Trajectory (HYSPLIT) model back trajectory analysis to the 
Denton County and Harris County, Texas, receptors.\42\ This HYSPLIT 
analysis evaluates back trajectories of 72 hours in time for the 2018-
2020 3-year period.\43\ Alabama claims that during the period 2018-
2020, the HYSPLIT model showed that, for Harris County, air moved over 
Alabama on only four of 31 exceedance days, and for Denton County, air 
moved over Alabama on only four of 26 exceedance days. Alabama asserts 
that of those days, weather patterns do not indicate that upper-level 
transport of emissions from Alabama would have contributed to 
concentrations at those monitors. Alabama also asserts that on days 
when wind flow suggests that Alabama could have contributed to 
exceedances at the Texas monitors, the air quality index (AQI) 
indicated good or moderate air quality in Alabama. Alabama thus 
concludes that, based on the back trajectories, monitored exceedances 
at the Texas receptors are locally driven. Alabama also notes that the 
design values for the two Texas monitors have been stagnant, while 
design values in Alabama continue to trend downward.
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    \42\ According to Alabama, the HYSPLIT analysis were generated 
using EPA's 2015 Ozone Designation Mapping Tool, available at 
https://www.epa.gov/ozone-designations/ozone-designations-guidance-
and-
data#:~:text=The%20ozone%20designations%20mapping%20tool,for%20the%20
2015%20Ozone%20NAAQS.
    \43\ See Attachment A of Alabama's June 21, 2022, SIP submission 
in Docket ID No. EPA-R04-OAR-2021-0841.
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e. Alabama NOX Emission Trends--Step 3 of 4-Step Framework
    Alabama reviewed their statewide NOX emissions for point 
and mobile sources. Alabama indicates that the highest contributor of 
NOX emissions in the State are from mobile sources but 
indicated that NOX emissions from this source category have 
decreased and would continue to decrease nationwide due to turnover in 
the gasoline and diesel fleets and due to the rise in use of electric 
vehicles. Alabama asserts that statewide NOX emissions from 
point sources (EGU and non-EGU) continue to decline and asserts there 
has been ``a precipitous drop in tonnage in our major source emissions 
inventory.'' Alabama claims that the 2017 NEI indicates that 
NOX emissions will ``continue to decline'' from point 
sources and ``continue to increase'' from mobile sources. Alabama 
asserts that controls on mobile sources should be evaluated first. 
Lastly, the State acknowledges that the largest NOX emission 
sources are in the Birmingham area (Jefferson County and Shelby

[[Page 64421]]

County) and the Mobile area (Mobile County and Escambia County) and, of 
these sources, the biggest emitters are EGUs. However, Alabama asserts 
that NOX emissions from EGUs have declined on the order of 
80 percent and that an overwhelming majority of these EGUs are already 
fully controlled.
2. ADEM's Response to Comments
    Alabama received two sets of comments during their State public 
comment period from Alabama Power and Southern Company (jointly 
referred to as Alabama Power) and from Sierra Club.\44\ Alabama's 
``Reconciliation of Comments Received'' \45\ states that Alabama 
Power's comments were generally supportive of [ADEM]'s proposed plan 
and included additional information which bolsters the Department's 
reasoning for adopting the plan. The comments did provide some 
additional information for supporting the proposed plan. Therefore, the 
Department is making a modification of the proposed plan by adding the 
following statement: ``It is also important to note that the 2016v2 
modeling platform does not identify any significant (>1%) linkages for 
Alabama in 2026.'' ADEM acknowledged that Sierra Club submitted adverse 
comments opposed to the proposed plan, and stated that ``none of the 
comments led ADEM to conclude that changes to the proposed plan were 
necessary,'' but did not address the substance of these comments.
---------------------------------------------------------------------------

    \44\ See comments submitted with Alabama's June 21, 2022, 2015 
ozone transport SIP package found in Docket ID No. EPA-R04-OAR-2021-
0841.
    \45\ See Part C, pdf p. 76, in Alabama's June 21, 2022, SIP 
submission in Docket ID No. EPA-R04-OAR-2021-0841.
---------------------------------------------------------------------------

    Apart from the statements noted above, the State does not 
explicitly discuss Alabama Power's or Sierra Club's legal, technical, 
and policy arguments. Therefore, EPA will treat Alabama's June 21, 
2022, ozone transport SIP narrative and WOE analysis as not relying on 
the legal, technical, or policy arguments provided in comments except 
as expressly stated by Alabama.

III. EPA's Evaluation of Alabama's 2015 Ozone Interstate Transport SIP 
Submission

    EPA is proposing to find that Alabama's June 21, 2022, SIP 
submission does not meet Alabama'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 EPA's evaluation of the SIP submission using the 4-step 
interstate transport framework. EPA is therefore proposing to 
disapprove Alabama's June 21, 2022, submission.

A. Results of EPA's Step 1 and Step 2 Modeling and Findings for Alabama

    As described in Section I of this document, EPA performed updated 
air quality modeling to project design values and contributions for 
2023. These data were examined to determine if Alabama 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 1, the data \46\ indicate that in 2023, emissions from 
Alabama contribute greater than 1 percent of the standard to a 
nonattainment receptor in Harris County, Texas (ID#: 482010055) and a 
maintenance-only receptor in Denton County, Texas (ID#: 481210034).\47\
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    \46\ The ozone design values and contributions at individual 
monitoring sites nationwide are provided in the file 
``2016v2_DVs_state_contributions.xlsx'' which is included in Docket 
ID No. EPA-HQ-OAR-2021-0663.
    \47\ 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 of this document. That 
modeling showed that Alabama 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 ID No. EPA-HQ-OAR-2021-0663.

                       Table 1--Alabama Linkage Results Based on EPA Updated 2023 Modeling
----------------------------------------------------------------------------------------------------------------
                                                                   2023 Average    2023 Maximum       Alabama
       Receptor ID              Location         Nonattainment/    design value    design value    contribution
                                                  maintenance          (ppb)           (ppb)           (ppb)
----------------------------------------------------------------------------------------------------------------
482010055................  Harris County,      Nonattainment....            71.0            72.0            0.88
                            Texas.
481210034................  Denton County,      Maintenance......            70.4            72.2            0.71
                            Texas.
----------------------------------------------------------------------------------------------------------------

B. Evaluation of Information Provided by Alabama Regarding Step 1

    At Step 1 of the 4-step interstate transport framework, Alabama 
relied on EPA's 2016v2 modeling platform to identify nonattainment and 
maintenance receptors in 2023. As described in Section I.D. of this 
document, EPA's 2016v2 modeling platform relies on the most recently 
available and technically appropriate information. EPA proposes to rely 
on this modeling to identify nonattainment and maintenance receptors in 
2023. That information establishes that there are two receptors to 
which Alabama is projected to be linked in 2023.
1. Evaluation of Alabama's Approach to Maintenance Receptors
    Based on this information, the State attempted to apply an 
alternative definition of a maintenance receptor utilizing the 
potential concepts included in the October 2018 memorandum. This 
memorandum included a description of the approach that EPA has 
historically used to identify maintenance-only receptors \48\ and 
identified potential alternative ways to define maintenance receptors 
based on certain criteria suggested in the memorandum, including an 
evaluation of meteorology conducive to ozone formation, review of ozone 
monitored concentrations, and precursor emissions trends.
---------------------------------------------------------------------------

    \48\ See Section I.D., of this document for a discussion of 
EPA's approach to identify maintenance receptors.
---------------------------------------------------------------------------

    EPA recognized in the October 2018 memorandum that states could 
potentially, with sufficient justification, establish an approach for 
addressing maintenance receptors that gives independent significance to 
prong 2 in some manner different than EPA's approach. In addition, the 
October 2018 memorandum identified two potential concepts that states 
could use to identify maintenance receptors: (1) States may, in some 
cases, eliminate a site as a maintenance receptor if the site is 
currently measuring clean data, or (2) in some cases, use a design 
value from the base period that is not the maximum design value. For 
either of these alternative methods, to adequately consider areas 
struggling to meet the NAAQS, EPA also indicated that it

[[Page 64422]]

expects states to include with their SIP demonstration a technical 
analysis showing that the following three criteria are met:
     Meteorological conditions in the area of the monitoring 
site were conducive to ozone formation during the period of clean data 
or during the alternative base period design value used for 
projections; \49\
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    \49\ See Attachment A of EPA's October 2018 memorandum to assess 
whether particular summers had ozone-conducive or unconducive 
meteorology within the 10-year period 2008 through 2017. The 
memorandum states that meteorological conditions including 
temperature, humidity, winds, solar radiation, and vertical mixing 
affect the formation and transport of ambient ozone concentrations. 
The memorandum suggests generally that above-average temperatures 
are an indication that meteorology is conducive to ozone formation 
and below average temperatures indicate that conditions are 
unconducive to ozone formation. Within a particular summer season, 
the degree that meteorology is conducive for ozone formation can 
vary from region to region and fluctuate with time within a 
particular region.
---------------------------------------------------------------------------

     Ozone concentrations have been trending downward at the 
site since 2011 (and ozone precursor emissions of NOX and 
VOC have also decreased); and
     Emissions are expected to continue to decline in the 
upwind and downwind states out to the attainment date of the receptor.
    EPA's October 2018 memorandum explained that the intent of the 
analysis is to demonstrate that monitoring sites that would be 
identified as maintenance receptors under EPA's historical approach 
could nonetheless be shown to be very unlikely to violate the NAAQS in 
the future analytic year.
    However, Alabama's WOE analysis provides limited supporting 
information to show that the Denton County, Texas, maintenance receptor 
is unlikely to violate the NAAQS in 2023. Regarding the first 
criterion, ADEM does not identify any periods of clean data for the 
Denton County, Texas, maintenance receptor for which meteorological 
conditions could be assessed to determine whether particular summers 
had ozone-conducive or unconducive meteorology during a period of clean 
data. Alabama also does not attempt to discuss or consider how 
meteorological factors identified in the October 2018 memorandum (such 
as temperature, humidity, solar radiation, vertical mixing, and/or 
other meteorological indicators such as cooling-degree days) confirm 
whether conditions affecting the monitor may have been conducive to 
ozone formation, nor did ADEM identify a specific calendar timeframe.
    With respect to the second criterion, ADEM's submission does not 
establish that there is a downward ozone design value trend for the 
Denton monitor. Furthermore, EPA does not observe any consistent 
downward trend for the 3-year average of the 4th highest daily maximum 
8-hour ozone concentration at the Denton County receptor from 2011 
through 2021.\50\ The available information in the submittal (see pdf 
p. 145) shows that DVs at this receptor are flat or increasing.
---------------------------------------------------------------------------

    \50\ See measured 2015 8-hour ozone design values from Table 6--
``Monitor Trends'' in the file 
O3_DesignValues_2019_2021_FINAL_05_25_22 at https://www.epa.gov/air-trends/air-quality-design-values.
---------------------------------------------------------------------------

    With respect to the third criterion, ADEM alludes to expected 
emissions reductions from fully controlled EGUs in Alabama for 
NOX for point sources, fleet turnover of gas and diesel 
mobile sources in coming years, a rise in the use of electric vehicles, 
and existing SIP-approved and Federal regulations of point sources and 
mobile sources. However, the State does not quantify the NOX 
emission reduction potential of existing controlled EGUs, fleet 
turnover of mobile sources, increase in electric vehicles, or current 
regulations for point and mobile sources such that their downwind 
contribution is addressed.\51\ Additionally, while the State does make 
summary statements, Alabama does not provide details to demonstrate why 
or how NOX emissions from sources in Alabama or Texas are 
expected to continue to decline through the next attainment date for 
the Dallas-Fort Worth-Arlington, Texas, area.
---------------------------------------------------------------------------

    \51\ EPA accounts for, and projects whether, receptors may have 
trouble attaining the NAAQS through the use of projected maximum 
design values in the relevant analytic year. Further, EPA's modeling 
of the relevant analytic year also already accounts for projected 
emissions trends of the upwind state (among others) and may (and 
often does) identify a linkage to areas that may struggle to 
maintain the NAAQS despite an overall declining emissions trend. 
This is not surprising. First, most maintenance receptors in EPA's 
projections are currently measuring nonattainment, meaning that, 
despite projecting improved air quality in the future analytic year, 
the receptor location is currently, and may continue to be, near the 
level of the NAAQS. Second, ozone levels are influenced by 
meteorological variability and thus high ozone levels may persist 
despite declining emissions as a result of recurring or worsening 
ozone-conducive atmospheric conditions (e.g., higher temperatures).
---------------------------------------------------------------------------

    Alabama's analysis supporting the use of an alternative definition 
for a maintenance receptor is insufficient. Furthermore, EPA does not 
observe any consistent downward trend for the 3-year average of the 4th 
highest daily maximum 8-hour ozone concentration at the Denton County 
receptor from 2011 through 2021. Thus, under the terms of the October 
2018 memorandum, Alabama's SIP submission does not adequately establish 
a basis for eliminating the Denton County monitoring site as a 
maintenance receptor.

C. Evaluation of Information Provided by Alabama Regarding Step 2

    In this action, EPA proposes to rely on the Agency's most recently 
available modeling to identify upwind contributions and ``linkages'' to 
downwind air quality problems in 2023 using a threshold of 1 percent of 
the NAAQS. See Section I.D of this document for a general explanation 
of the use of 1 percent of the NAAQS. EPA evaluates Alabama's use of an 
alternative threshold of 1 ppb in Section III.C.3. of this document 
below. As shown in Table 1 of this document, updated EPA modeling 
identifies Alabama's maximum contribution to downwind nonattainment and 
maintenance receptors as greater than 1 percent of the standard (i.e., 
0.70 ppb). Therefore, the State is linked to a downwind air quality 
problem at Steps 1 and 2 in 2023.\52\ Alabama acknowledges EPA's 2016v2 
updated modeling platform's projected contributions to nonattainment 
and maintenance receptors in 2023, but concludes Alabama does not 
contribute above 1 ppb of the NAAQS at any monitors that are projected 
to be in nonattainment or maintenance, and argues that is an acceptable 
threshold to use. EPA proposes to disapprove Alabama's SIP submission 
based on EPA's finding that the State is linked to receptors in 2023 
using the one percent threshold, and the State's arguments in support 
of using a 1 ppb threshold are not approvable.
---------------------------------------------------------------------------

    \52\ Alabama states in its submission that EPA's 2016v2 modeling 
platform does not identify any significant linkages for Alabama to 
downwind receptors, greater than one percent of ozone NAAQS in 2026. 
EPA agrees that this is what the 2016v2 modeling shows; however, 
that does not diminish the conclusion that a linkage does exist in 
the relevant analytic year for the next attainment date, which is 
2023.
---------------------------------------------------------------------------

1. Evaluation of Alabama's Analysis of 2016v2 Modeling Platform 
Performance
    The Alabama SIP submission states that EPA's 2016v2 modeling 
platform cannot account for a 0.71 ppb threshold which Alabama claims 
is within the margin of error for the model, asserting that when 
considering the magnitude of the so-called margin of error, the small 
threshold could not accurately account for impacts hundreds of miles 
away to a downwind receptor. (EPA interprets these statements as 
relating to the one-percent threshold, which is 0.70 ppb for the 2015 
ozone NAAQS.) Alabama's WOE analysis cites EPA's Modeling TSD, ``Air 
Quality Modeling for the 2016v2 Emissions Platform Technical

[[Page 64423]]

Support Document: Appendix A,'' which Alabama claims identifies that 
there is bias and error in the modeling ranging from 2.9 to 
6.1 ppb in the Southeast region (which includes Alabama, Georgia, 
Florida, South Carolina, North Carolina, and Virginia) and 7.8 to 9.1 ppb in the South region (which includes Texas, 
Louisiana, Mississippi, Arkansas, Oklahoma, and Kansas).
    Alabama misunderstands the meaning of the terms and figures 
provided by EPA in this TSD and conflates two different concepts: model 
bias and model error. For days with maximum daily average 8-hour (MDA8) 
concentrations greater than or equal to 60 ppb, EPA's TSD found average 
bias was -2.9 ppb in the Southeast region and -7.8 ppb in the South 
region, whereas average error was 6.1 ppb in the Southeast and 9.1 ppb 
in the South. Model bias can be positive or negative, but model error 
is always a positive value. Thus, EPA's TSD identifies model bias of -
2.9 and -7.8 ppb and model error of 6.1 ppb and 9.1 ppb in the 
Southeast and South regions, respectively. In other words, EPA found 
that the model tended to under-predict actual ozone levels at 
monitoring sites in these regions. Note that EPA evaluates linkages 
using the multi-day average contribution from each upwind state to each 
downwind receptor based on daily contributions from the State to the 
receptor for the days with the highest model-predicted future year 
concentrations. The modeled data are intended to represent future year 
ozone concentrations and contributions associated with ozone conducive 
meteorological conditions and transport patterns typical for high ozone 
episodes at the receptor. In this regard, base year model performance 
statistics that are derived from measured and modeled data strictly 
paired in space and time are not useful as the sole measure for gauging 
the ability of the model to adequately estimate future year average 
contributions on the order of 0.70 ppb on high ozone days 
representative of the magnitude of measured concentrations at the 
receptor. Further, with respect to model ``error,'' as explained in 
EPA's TSD, the performance of our modeling is within the generally 
accepted performance parameters for modeling of this type.\53\ Finally, 
while EPA concedes that its modeling cannot perfectly project air 
quality levels and contributions in a future year, EPA has successfully 
applied its CAMx modeling platform across many CAA regulatory actions 
and continues to find the modeling reliable for purposes of the Step 1 
and Step 2 analyses of the 4-Step Framework. If EPA were unable to draw 
reasonable conclusions from the results of its future-year modeling 
projections at ppb intervals smaller than 6.1 or 9.1 ppb, it would 
effectively mean the Agency is incapable of making virtually any 
conclusions with respect to interstate ozone transport, which would 
frustrate the purposes of the Act. EPA must implement its statutory 
mandates in the face of uncertainty unless that uncertainty is ``so 
profound that it precludes . . . reasoned judgment.'' Wisconsin, 938 
F.3d at 319; see also EME Homer City v. EPA, 795 F.3d 118, 135 (D.C. 
Cir. 2015) (``We will not invalidate EPA's predictions solely because 
there might be discrepancies between those predictions and the real 
world.''). We do not believe the modeling, our evaluation of that 
modeling, or the record overall prevents the Agency from rendering a 
reasonable judgment that Alabama contributes above 1 percent of the 
NAAQS at the two receptors in Texas in 2023 based on the 2016v2 
modeling. See Sierra Club v. EPA, 939 F.3d 649, 686-87 (5th Cir. 2019) 
(upholding EPA's modeling in the face of complaints regarding an 
alleged ``margin of error,'' noting challengers face a ``considerable 
burden'' in overcoming a ``presumption of regularity'' afforded ``the 
EPA's choice of analytical methodology'') (citing BCCA Appeal Grp. v. 
EPA, 355 F.3d 817, 832 (5th Cir. 2003)).
---------------------------------------------------------------------------

    \53\ See Air Quality Modeling Technical Support Document, 
Appendix A, in Docket ID No. EPA-HQ-OAR-2021-0663.
---------------------------------------------------------------------------

2. Evaluation of Alabama's Consideration of an Alternative Significant 
Contribution Threshold
    In their June 21, 2022, SIP submission, Alabama states that EPA's 
March and August 2018 memoranda allow for flexibility to determine 
significance and establish a significance level of 1 ppb as a 
sufficient threshold. Alabama then determines that the threshold should 
be set at 1 ppb to support their conclusion that Alabama would not be 
linked to any projected downwind nonattainment or maintenance 
receptors. See Section II.B of this document. Alabama does not argue in 
its submittal that 1 percent of the NAAQS would not be an appropriate 
threshold for upwind contribution to the Texas receptors. Alabama's 
submission instead asserts that the State is not linked at Step 2 
because the March and August 2018 memoranda identified a 1 ppb 
threshold as a sufficient threshold.
    EPA proposes to find that Alabama's reliance on an alternative 
contribution threshold of 1 ppb at Step 2 is not approvable. EPA 
acknowledges that the August 2018 memorandum generally recognized that 
a 1 ppb threshold may be appropriate for states to use, but also made 
clear that this guidance would be applied under the facts and 
circumstances of each SIP submittal.\54\ However, Alabama did not 
provide a technical analysis to sufficiently justify use of an 
alternative 1 ppb threshold at the linked, downwind monitors. Alabama's 
SIP submission simply states that ADEM agrees with EPA's rationale set 
out in the August 2018 memorandum that the amount of upwind collective 
contribution captured with the 1 percent and 1 ppb thresholds was 
generally comparable. But the guidance anticipated that states would 
evaluate whether the alternative threshold was appropriate under their 
specific facts and circumstances, not that the use of the alternative 
threshold would be automatically approvable.\55\ With respect to the 
assertion that 1 ppb was generally comparable to 1 percent, Alabama 
does not provide discussion or analysis containing information specific 
to the State or a receptor analysis for the affected monitors, as 
anticipated in the August 2018 memorandum, to evaluate whether the 
alternative threshold was appropriate to apply with respect to the 
monitors to which Alabama was linked. Such state-specific information 
is necessary to thoroughly evaluate the state-specific circumstances 
that could support approval.
---------------------------------------------------------------------------

    \54\ See August 2018 memorandum at 1.
    \55\ As an example of the type of analysis that EPA anticipated 
states might conduct under the guidance, in one instance, EPA itself 
attempted to conduct a state- and receptor-specific analysis that 
could support approval of the use of a 1 ppb threshold. See Air Plan 
Approval; Iowa; Infrastructure State Implementation Plan 
Requirements for the 2015 Ozone National Ambient Air Quality 
Standard, 85 FR 12232 (March 2, 2020). The Agency received adverse 
comment on this proposed approval and has subsequently formally 
withdrawn the proposed approval. See 87 FR 9477 (February 22, 2022).
---------------------------------------------------------------------------

    Alabama's SIP also claims there is precedent for setting a 1 ppb 
``significance'' threshold for ozone in the PSD permitting program. 
However, the State's implementation plan submission does not elaborate 
on this assertion. EPA has provided guidance identifying a 1.0 ppb 8-
hour ozone NAAQS significant impact level (SIL) for use by PSD 
permitting authorities.\56\ The PSD program applies in areas that are 
designated attainment or

[[Page 64424]]

unclassifiable for the NAAQS,\57\ and a SIL is a screening tool used to 
determine whether a PSD permit applicant is required to perform a 
comprehensive, cumulative modeling analysis that involves evaluating 
the impact of the new facility in addition to impacts from other 
existing sources in the area. Good neighbor analysis for the ozone 
NAAQS, by contrast, addresses the degree of significant contribution to 
nonattainment and interference with maintenance of the NAAQS resulting 
at downwind receptors from the collective contribution of many upwind 
sources. This fundamental difference in purpose between SIL thresholds 
and the interstate transport contribution threshold used under CAA 
section 110(a)(2)(D)(i)(I) has been recognized since at least the 2005 
Clean Air Interstate Rule.\58\ Further, it is not correct to conflate 
the use of the term ``significance,'' as used in the SIL guidance, with 
the term ``contribution,'' which is the appliable statutory term that 
EPA applies at Step 2 of the 4-step interstate transport framework. 
(``Significance'' within the 4-step framework is evaluated at Step 3 
through a multifactor analysis for those states that are determined to 
``contribute'' to downwind receptors at Steps 1 and 2. See Section 
I.D.4. of this document). Given the fundamentally different statutory 
objectives and context, EPA disagrees with Alabama's contention that 
the SIL guidance is applicable in the good neighbor context.
---------------------------------------------------------------------------

    \56\ See Guidance on Significant Impact Levels for Ozone and 
Fine Particles in the Prevention of Significant Deterioration 
Permitting Program, April 17, 2018, available at https://www.epa.gov/sites/default/files/2018-04/documents/sils_policy_guidance_document_final_signed_4-17-18.pdf.
    \57\ Pursuant to section 107(d) of the CAA, EPA must designate 
areas as either ``nonattainment,'' ``attainment,'' or 
``unclassifiable.'' During initial designations for the ozone NAAQS, 
EPA has designated most areas that do not meet the definition of 
nonattainment as ``unclassifiable/attainment'' or ``attainment/
unclassifiable.'' This category includes areas that have air quality 
monitoring data meeting the NAAQS and areas that do not have 
monitors but for which EPA has no evidence that the areas may be 
violating the NAAQS or contributing to a nearby violation.
    \58\ See 70 FR at 25191, May 12, 2005 (``The implication of the 
[SIL] thresholds cited by the commenters is not that single-source 
contributions below these levels indicate the absence of a 
contribution. Rather, these thresholds address whether further, more 
comprehensive, multi-source review or analysis of appropriate 
control technology and emissions offsets are required of the source. 
A source with estimated impacts below these levels is recognized as 
still affecting the airshed and is subject to meeting applicable 
control requirements, including best available control technology, 
designed to moderate the source's impact on air quality.'') 
(emphasis added).
---------------------------------------------------------------------------

    Given the absence of technical analysis to support the use of a 1 
ppb threshold under the facts and circumstances relevant to Alabama and 
its linked receptors, EPA proposes that the use of 1 ppb as a 
contribution threshold is not approvable. As discussed in Section 
I.D.3.of this document above, EPA no longer intends to dedicate 
resources to supplement State submittals with insufficient analysis in 
this regard and also has identified other policy and programmatic 
concerns with attempting to recognize alternative thresholds at Step 2 
or otherwise deviating from its historical, consistent practice of 
applying a threshold of 1 percent of the NAAQS. EPA views the 1 percent 
of NAAQS threshold as the more appropriate threshold, as explained 
elsewhere in this document.\59\ EPA's experience with the alternative 
Step 2 thresholds is further discussed in Section I.D.3. of this 
document.
---------------------------------------------------------------------------

    \59\ EPA notes the explanation for how the 1 percent 
contribution threshold was originally derived is available in the 
2011 CSAPR rulemaking. See 76 FR 48208, 48237-38, August 8, 2011. 
Further, in the CSAPR Update, EPA re-analyzed the threshold for 
purposes of the 2008 ozone NAAQS and determined it was appropriate 
to continue to apply this threshold. See 81 FR 74504, 74518-19, 
October 26, 2016.
---------------------------------------------------------------------------

3. Evaluation of Alabama's Analysis of Meteorological Influence and 
HYSPLIT Back Trajectories
    Alabama's WOE analysis includes a HYSPLIT model back trajectory 
analysis to the Denton County and Harris County, Texas, receptors.\60\ 
This HYSPLIT analysis evaluates back trajectories of 72 hours in time, 
for the 2018-2020 3-year period.\61\ Alabama used these HYSPLIT back 
trajectories to emphasize the local nature of the ozone precursor 
emissions at the two Texas receptors.\62\ However, the information 
provided by Alabama is not adequate to support approval of the State's 
implementation plan submittal on this basis.
---------------------------------------------------------------------------

    \60\ According to Alabama, the HYSPLIT analysis were generated 
using EPA's 2015 Ozone Designation Mapping Tool, available at 
https://www.epa.gov/ozone-designations/ozone-designations-guidance-
and-
data#:~:text=The%20ozone%20designations%20mapping%20tool,for%20the%20
2015%20Ozone%20NAAQS.
    \61\ See Attachment A of Alabama's June 21, 2022, SIP submission 
in Docket ID No. EPA-R04-OAR-2021-0841.
    \62\ See id.
---------------------------------------------------------------------------

    Alabama asserts that on days when wind flow suggests that could 
have contributed to exceedances at the Texas monitors, the AQI 
indicated good or moderate air quality in Alabama. Alabama explains 
that in the HYSPLIT model for Harris County, during 2018-2020, only 
four of 31 exceedance days showed air that moved over Alabama, and in 
Denton County, during the same period, only three of 26 exceedance days 
showed air that moved over Alabama. Alabama asserts that of those days, 
weather patterns do not indicate that upper-level transport of 
emissions from Alabama would have contributed to concentrations at 
those monitors. Alabama thus concludes that, based on the back 
trajectories, monitored exceedances at the Texas receptors are locally 
driven. Alabama also notes that the design values for the two Texas 
monitors have been stagnant, while design values in Alabama continue to 
trend downward.
    As an initial matter, the images supplied by ADEM showing a map of 
the south-central and southeast United States with ozone concentration 
gradients on specific days do not reveal any information that would 
call into question the results of EPA's photochemical grid modeling. 
These images purport to show that on days when there are high ozone 
levels at the receptor areas in Dallas and Houston, or in the days 
preceding those high-ozone events, ozone concentrations in the State of 
Alabama were relatively low. However, it has long been understood that 
ozone concentrations in downwind areas are affected not by the 
transport of ozone per se from upwind areas, but from ozone formed 
downwind from the ozone-precursor emissions, such as NOX, in 
the upwind state. Thus, it is not at all unusual that an upwind source 
area could have relatively low ozone levels in the days preceding a 
high ozone event at a downwind receptor area; sources and other 
emissions activities in that State nonetheless may be emitting ozone-
precursor emissions in amounts sufficient to contribute ozone above one 
percent of the NAAQS to the high-ozone event that occurs at the 
downwind receptor.\63\
---------------------------------------------------------------------------

    \63\ See Moghani, M., The effects of transport, climate, and 
emissions on ozone pollution in the U.S. University of Delaware 
Press, 2020. https://udspace.udel.edu/handle/19716/27961; Atkinson, 
R., ``Atmospheric chemistry of VOCs and NOX. Atmospheric 
Environment 34 (2000) 2063-2101; National Research Council 1991. 
Rethinking the Ozone Problem in Urban and Regional Air Pollution. 
Washington, DC. The National Academies Press. http://doi.org/10.17226/1889.
---------------------------------------------------------------------------

    Further, ADEM uses HYSPLIT back trajectories to purport to 
demonstrate that air parcels transporting from Alabama do not transect 
Alabama for a long enough period of time to have a meaningful impact at 
the downwind receptor. But once again, the data supplied by the State 
do not call into question the results of EPA's photochemical grid 
modeling. First, the back trajectories supply limited information, 
showing only the pathway of air currents that reach a receptor area 
during a high-ozone event. They do not display emissions levels in the 
areas traversed by and transported by those air currents. Further, the 
figures provided by ADEM establish that air

[[Page 64425]]

parcels do in fact move over Alabama during meteorological patterns 
that result in high ozone levels at downwind receptors. In addition, 
the vectors of the back trajectories only show the center line of air 
flow. In other words, the breadth of the air currents represented by 
the back trajectory is much wider than the single line displayed in the 
images, and thus, a broader parcel of air covering a wider region can 
assume to be transported based on the line displayed. Thus, the back 
trajectories supplied by ADEM do not provide compelling evidence that 
EPA's photochemical grid modeling is unreliable.

D. Evaluation of Information Provided by Alabama 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. 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 interfere 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 EPA has not directed states that 
they must conduct a Step 3 analysis in precisely the manner 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 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. Alabama does not include 
such an analysis in its SIP submission.
    Alabama's SIP submission does not contain a Step 3 analysis 
regarding future emissions reduction opportunities beyond pointing to 
NOX emission reductions from SIP-approved and Federal 
measures. Alabama's submission cursorily evaluates NOX 
emissions from point and mobile source categories from the 2017 NEI and 
suggests a steep decline in the major source emissions inventory. This 
includes an assertion that NOX emissions from EGUs have 
declined on the order of 80 percent and that an overwhelming majority 
of these EGUs are already fully controlled. However, these claims are 
not supported in the submittal with any specific timeframe or baseline 
from which the asserted decline in point source or mobile source 
emissions have been measured, or a quantitative demonstration that 
explains how or why the asserted decline in NOX emission 
would be sufficient to eliminate Alabama's significant contribution. 
Alabama does not include a comprehensive accounting of facilities in 
the State and does not include a sufficient analysis of potential 
NOX emissions control technologies, their associated costs, 
estimated emissions reductions, and downwind air quality improvements 
for the purpose of identifying what additional emission controls may be 
necessary to eliminate their significant contribution.
    Alabama's SIP also argues that the highest NOX emissions 
in the State are from mobile sources, not point sources, suggesting 
that ozone is created and remains locally in Alabama rather than 
transported to downwind states. However, these claims are not supported 
by any evidence. The State's back trajectories do not provide any 
technical demonstration that supports the claim that NOX 
emissions, specifically mobile emissions, remain local (see Section 
III.C. of this document).
    Further, Alabama asserts that since mobile source emissions are the 
``highest'' source category of emissions in the State, they should be 
evaluated first for purposes of interstate transport. However, the 
State conducted no such analysis of methods or control techniques that 
could be used to reduce mobile source emissions in the State, instead 
insinuating that it cannot ``reasonably'' control mobile source 
emissions.\64\ States do have options, however, to reduce emissions 
from certain aspects of their mobile source sectors, and to the extent 
the State is attributing its contribution to out of State receptors to 
its mobile sources, it could have conducted an analysis of possible 
programs or measures that could achieve emissions reductions from those 
sources. (For example, a general list of types of transportation 
control measures can be found in CAA section 108(f).\65\
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    \64\ See Alabama's WOE Analysis in the June 21, 2022, submittal 
(pdf p. 106), stating that ``Alabama point source NOX 
emissions [are] the only emissions that Alabama can reasonably 
control.''
    \65\ In making this observation, EPA is not suggesting that 
mobile source emissions reductions are necessarily required to 
address Alabama's good neighbor obligations, but merely pointing out 
that if the State itself attributes the problem to mobile sources, 
then it is reasonable to expect that further analysis of such 
control strategies would be explored.
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    Alabama provides information related to programs that potentially 
reduced NOX emissions in the State, such as SIP-approved and 
State regulations, Federal programs (including the CSAPR Update), and 
turnover in gasoline and diesel fleets and the rise in electric 
vehicles. Alabama thus determined that the SIP contains adequate 
provisions to prohibit emissions that will significantly contribute to 
nonattainment or interfere with maintenance of the 2015 8-hour ozone 
NAAQS in any other State. However, the State does not analyze total 
ozone precursors that continue to be emitted from sources and other 
emissions activity within the State, nor does ADEM quantify the 
NOX emission reduction potential of SIP-approved regulations 
or Federal programs or on-the-way measures for 2023 or consider the 
cost-effectiveness of potential additional emissions controls, the 
total emissions reductions that may be achieved by requiring these 
controls, or the air quality impacts such emissions reductions would 
have on the downwind receptors to which Alabama is linked. Identifying 
a range of on-the-books emissions control measures that have been or 
may be enacted at the State or local level, without analysis of the 
impact of those measures on the downwind receptors, is not a sufficient 
analysis. Additionally, EPA's modeling already takes account of on-the-
book measures. Despite these existing emissions controls, the State is 
projected in the most recently available modeling to be linked to at 
least one downwind nonattainment receptor and one maintenance receptor. 
The State was therefore obligated at Step 3 to

[[Page 64426]]

assess additional control measures using a multifactor analysis.
    Among the Federal programs referenced in Alabama's submission was 
the CSAPR Update NOX ozone season Group 2 trading program 
for the 2008 ozone standard, which ADEM adopted into the Alabama 
SIP.\66\ This reference suggests that Alabama may have intended to rely 
on its EGUs being subject to the CSAPR Update (which reflected a 
stringency at the nominal marginal cost threshold of $1,400/ton (in 
2011 dollars) for the 2008 8-hour ozone NAAQS) to argue that it has 
already implemented all cost-effective emissions reductions at EGUs.
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    \66\ See 81 FR 59869 (August 31, 2016), 82 FR 46674 (October 6, 
2017) (adopting Alabama Administrative Code Rule 335-3-8, ''Control 
of Nitrogen Oxides Emissions'' and adopting revisions to Rule 335-3-
8 into the SIP).
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    EPA does not support the concept that reliance on the CSAPR Update 
is appropriate to conclude that no further emissions reductions are 
necessary under Step 3 for the 2015 8-hour ozone NAAQS. Relying on the 
CSAPR Update's (or any other CAA program's) determination of cost-
effectiveness without further Step 3 analysis is not approvable. Cost-
effectiveness must be assessed in the context of the specific CAA 
program; assessing cost-effectiveness in the context of 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 EPA has not established a 
benchmark cost-effectiveness value for 2015 8-hour ozone NAAQS 
interstate transport obligations, it is reasonable to expect control 
measures or strategies to address interstate transport under this NAAQS 
to reflect higher marginal control costs because the 2015 8-hour ozone 
NAAQS is a more stringent and more protective air quality standard. As 
such, the marginal cost threshold of $1,400/ton for the CSAPR Update 
(which addresses the 2008 ozone 8-hour NAAQS and is in 2011 dollars) is 
not an appropriate cost threshold and cannot be approved as a benchmark 
to use for interstate transport SIP submissions for the 2015 8-hour 
ozone NAAQS. In addition, the updated EPA modeling captures all 
existing CSAPR trading programs in the baseline, and that modeling 
confirms that these control programs were not sufficient to eliminate 
Alabama's linkage at Steps 1 and 2 under the 2015 8-hour ozone NAAQS 
(even acknowledging that the CSAPR Update provisions have been adopted 
into Alabama's SIP). The State was therefore obligated at Step 3 to 
assess additional control measures using a multifactor analysis.
    As mentioned above, the 2016v2 modeling on which Alabama has relied 
in its June 2022 submittal indicates sources in Alabama are linked to 
downwind air quality problems for the 2015 ozone standard. Alabama's 
SIP submittal does not include an accounting of emissions sources and 
activity 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 Alabama present an alternative approach to assess which of its 
emissions should be deemed ``significant.'' EPA proposes to find that 
Alabama's analysis is insufficient to support the State's claim that 
its SIP adequately prohibits emissions within Alabama in a manner 
sufficient to address the State's interstate transport obligations for 
the 2015 8-hour ozone. Therefore, EPA proposes to disapprove Alabama's 
August 20, 2018, interstate transport SIP submission on the separate, 
additional basis that the SIP submittal did not assess additional 
emissions control opportunities.

E. Evaluation of Information Provided by Alabama 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 in Section 
III.D. of this document, Alabama's SIP submission did not contain an 
evaluation of additional emissions control opportunities (or establish 
that no additional controls are required), thus no information was 
provided at Step 4. As a result, EPA proposes to disapprove Alabama's 
August 20, 2018, 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).
    The previous section explained why EPA views Alabama's analysis at 
Step 3 as insufficient to demonstrate that the emissions reductions it 
asserts have occurred or may occur are sufficient to address the 
State's interstate transport obligations. At Step 4, EPA finds that 
ADEM has also not provided SIP revisions that would ensure the 
reductions it claims to rely on are rendered permanent and enforceable. 
As just one example, while Alabama stated that mobile source emissions 
would decline as use of electric vehicles grows, the State cited to no 
State program or enforceable measures to implement such an emissions-
reduction strategy. See Committee for a Better Arvin v. EPA, 786 F.3d 
1169, 1175-76 (9th Cir. 2015) (holding that measures relied on by a 
State to meet CAA requirements must be included in the SIP). As a 
result, EPA proposes to disapprove Alabama's June 21, 2022, 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).

IV. Conclusion for Alabama

    Based on EPA's evaluation of Alabama's SIP submission and after 
consideration of updated EPA modeling using the 2016-based emissions 
modeling platform, EPA is proposing to find that Alabama's June 21, 
2022, SIP submission 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.

V. Proposed Action

    EPA is proposing to disapprove the 2015 ozone good neighbor 
interstate transport SIP revision from Alabama, dated June 21, 2022. If 
EPA finalizes this disapproval, EPA will continue to be subject to an 
obligation to promulgate a FIP to address the relevant interstate 
transport requirements, which was triggered by the finding of failure 
to submit published on June 22, 2022. However, under the CAA, a good 
neighbor SIP disapproval does not start a mandatory sanctions clock.

VI. Statutory and Executive Order Reviews

A. Executive Order 12866: Regulatory Planning and Review and Executive 
Order 13563: Improving Regulation and Regulatory Review

    The proposed action is not a significant regulatory action and was 
therefore not submitted to the Office of Management and Budget for 
review.

B. Paperwork Reduction Act (PRA)

    The proposed action does not impose an information collection 
burden under the PRA because it does not contain any information 
collection activities.

[[Page 64427]]

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 (5 
U.S.C. 601 et seq.). This action merely proposes to disapprove a SIP 
submission as not meeting the CAA.

D. Unfunded Mandates Reform Act (UMRA)

    The proposed 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 proposed action imposes no 
enforceable duty on any State, local, or tribal governments or the 
private sector.

E. Executive Order 13132: Federalism

    The proposed 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: Consultation and Coordination With Indian 
Tribal Governments

    The proposed action does not have tribal implications as specified 
in Executive Order 13175. The proposed action does not apply on any 
Indian reservation land, any other area where EPA or an Indian tribe 
has demonstrated that a tribe has jurisdiction, or non-reservation 
areas of Indian country. Thus, Executive Order 13175 does not apply to 
this action.

G. Executive Order 13045: Protection of Children From Environmental 
Health Risks and Safety Risks

    EPA interprets Executive Order 13045 as applying only to those 
regulatory actions that concern environmental health or safety risks 
that 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 proposed action is not subject to Executive 
Order 13045 because it merely proposes to disapprove a SIP submission 
from Alabama as not meeting the CAA.

H. Executive Order 13211, Actions That Significantly Affect Energy 
Supply, Distribution or Use

    The proposed 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

    This proposed rulemaking does not involve technical standards.

J. Executive Order 12898: Federal Actions To Address Environmental 
Justice in Minority Populations and Low-Income Populations

    EPA believes the human health or environmental risk addressed by 
this proposed action will not have potential disproportionately high 
and adverse human health or environmental effects on minority, low-
income or indigenous populations. This proposed 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 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 EPA complete discretion whether to invoke 
the exception in (ii).\67\
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    \67\ 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 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), EPA interprets and 
applies section 110(a)(2)(d)(i)(I) of the CAA for the 2015 8-hour 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, 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 8-hour ozone NAAQS. 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, EPA proposes to determine and apply a set of 
nationally consistent policy judgments to apply the 4-step framework. 
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.\68\ 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).\69\
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    \68\ 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.
    \69\ 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 8-hour ozone 
NAAQS. Should EPA take a single final action on all such 
disapprovals, this action would be nationally applicable, and 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: October 17, 2022.
Daniel Blackman,
Regional Administrator, Region 4.
[FR Doc. 2022-22892 Filed 10-24-22; 8:45 am]
BILLING CODE 6560-50-P