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Proposed Rule2024-01064

Supplemental Air Plan Actions: Interstate Transport of Air Pollution for the 2015 8-Hour Ozone National Ambient Air Quality Standards and Supplemental Federal “Good Neighbor Plan” Requirements for the 2015 8-Hour Ozone National Ambient Air Quality Standards

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Published

February 16, 2024

Issuing agencies

Environmental Protection Agency

Abstract

Pursuant to the Federal Clean Air Act (CAA or the Act), the Environmental Protection Agency (EPA) is proposing to partially disapprove and partially approve State Implementation Plan (SIP) submissions from Arizona, Iowa, Kansas, New Mexico, and Tennessee regarding interstate transport for the 2015 8-hour ozone national ambient air quality standards (NAAQS). This action also proposes a Federal Implementation Plan (FIP) for Arizona, Iowa, Kansas, New Mexico, and Tennessee to address these States' obligations to eliminate significant contribution to nonattainment, or interference with maintenance, of the 2015 ozone NAAQS in other states. The FIP would require fossil fuel-fired power plants in the five states to participate in an allowance-based ozone season nitrogen oxides emissions trading program beginning in 2025. The Agency is also proposing to establish nitrogen oxides emissions limitations applicable to certain other industrial stationary sources in Arizona with a compliance year no earlier than 2027. Finally, this action also includes proposed technical corrections to the regulatory text previously promulgated to establish comparable FIP requirements for emissions sources in other states.

Full Text

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[Federal Register Volume 89, Number 33 (Friday, February 16, 2024)]
[Proposed Rules]
[Pages 12666-12741]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2024-01064]

[[Page 12665]]

Vol. 89

Friday,

No. 33

February 16, 2024

Part V

Environmental Protection Agency

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40 CFR Parts 52 and 97

Supplemental Air Plan Actions: Interstate Transport of Air Pollution
for the 2015 8-Hour Ozone National Ambient Air Quality Standards and
Supplemental Federal ``Good Neighbor Plan'' Requirements for the 2015
8-Hour Ozone National Ambient Air Quality Standards; Proposed Rule

Federal Register / Vol. 89, No. 33 / Friday, February 16, 2024 /
Proposed Rules

[[Page 12666]]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 52 and 97

[EPA-HQ-OAR-2021-0663; EPA-HQ-OAR-2021-0668; EPA-HQ-OAR-2023-0402; FRL-
11159-01-OAR]
RIN 2060-AW09

Supplemental Air Plan Actions: Interstate Transport of Air
Pollution for the 2015 8-Hour Ozone National Ambient Air Quality
Standards and Supplemental Federal ``Good Neighbor Plan'' Requirements
for the 2015 8-Hour Ozone National Ambient Air Quality Standards

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule; supplemental proposed rule and withdrawal of
proposed rules.

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SUMMARY: Pursuant to the Federal Clean Air Act (CAA or the Act), the
Environmental Protection Agency (EPA) is proposing to partially
disapprove and partially approve State Implementation Plan (SIP)
submissions from Arizona, Iowa, Kansas, New Mexico, and Tennessee
regarding interstate transport for the 2015 8-hour ozone national
ambient air quality standards (NAAQS). This action also proposes a
Federal Implementation Plan (FIP) for Arizona, Iowa, Kansas, New
Mexico, and Tennessee to address these States' obligations to eliminate
significant contribution to nonattainment, or interference with
maintenance, of the 2015 ozone NAAQS in other states. The FIP would
require fossil fuel-fired power plants in the five states to
participate in an allowance-based ozone season nitrogen oxides
emissions trading program beginning in 2025. The Agency is also
proposing to establish nitrogen oxides emissions limitations applicable
to certain other industrial stationary sources in Arizona with a
compliance year no earlier than 2027. Finally, this action also
includes proposed technical corrections to the regulatory text
previously promulgated to establish comparable FIP requirements for
emissions sources in other states.

DATES:
Comments: Comments must be received on or before May 16, 2024.
Public hearing: The EPA will hold a virtual public hearing on March
4, 2024. Please refer to the SUPPLEMENTARY INFORMATION section for
additional information on the public hearing.
Information collection request: Under the Paperwork Reduction Act
(PRA), comments on the information collection provisions are best
assured of consideration if the Office of Management and Budget (OMB)
receives a copy of your comments on or before March 18, 2024.

ADDRESSES:
Comments: You may send comments, identified as Docket ID No. EPA-
HQ-OAR-2023-0402, by any of the following methods: Federal eRulemaking
Portal: <a href="https://www.regulations.gov/">https://www.regulations.gov/</a>. Follow the online instructions
for submitting comments. Include Docket ID No. EPA-HQ-OAR-2023-0402 in
the subject line of the message.
Instructions: All submissions received must include the Docket ID
No. for this rulemaking. Comments received may be posted without change
to <a href="https://www.regulations.gov">https://www.regulations.gov</a>, including any personal information
provided. For detailed instructions on sending comments and additional
information on the rulemaking process, see the ``Public Participation''
heading of the SUPPLEMENTARY INFORMATION section of this document.
Hearing: The virtual hearing will be held at <a href="https://www.epa.gov/csapr/csapr-2015-ozone-naaqs">https://www.epa.gov/csapr/csapr-2015-ozone-naaqs</a>. The public hearing will convene at 9:00
a.m. and end at 6:00 p.m. Eastern Time (ET) or 1 hour after the last
registered speaker has spoken. The EPA will make every effort to
accommodate all individuals interested in providing oral testimony. A
lunch break is scheduled from 12:00 p.m. until 1:00 p.m. Refer to the
SUPPLEMENTARY INFORMATION section for additional information.

FOR FURTHER INFORMATION CONTACT: Thomas Uher, Air Quality Policy
Division, Office of Air Quality Planning and Standards (C539-04),
Environmental Protection Agency, 109 TW Alexander Drive, Research
Triangle Park, NC 27711; telephone number: (919) 541-5534; email
address: <a href="/cdn-cgi/l/email-protection#13667b76613d677b7c7e7260537663723d747c65">[email&#160;protected]</a>.

SUPPLEMENTARY INFORMATION:
Public participation: Submit your comments, identified by Docket ID
No. EPA-HQ-OAR-2023-0402, at <a href="https://www.regulations.gov">https://www.regulations.gov</a> (our preferred
method. Once submitted, comments cannot be edited or removed from the
docket. The EPA may publish any comment received to its public docket.
Do not submit to the EPA's docket at <a href="https://www.regulations.gov">https://www.regulations.gov</a> 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. The EPA
will generally not consider comments or comment contents located
outside of the primary submission (i.e., on the web, cloud, or other
file sharing system).
There are three dockets supporting this action, EPA-HQ-OAR-2023-
0402, EPA-HQ-OAR-2021-0663, and EPA-HQ-OAR-2021-0668. All comments
regarding information in any of these dockets are to be made in Docket
ID No. EPA-HQ-OAR-2023-0402.
The index to the docket for this action, Docket ID No. EPA-HQ-OAR-
2023-0402, is available electronically at <a href="https://www.regulations.gov">https://www.regulations.gov</a>.
While all documents in the docket are listed in the index, some
information may not be publicly available due to docket file size
restrictions or content (e.g., CBI).

Preamble Glossary of Terms and Abbreviations

The following are abbreviations of terms used in the preamble.

2016v1 2016 Version 1 Emissions Modeling Platform
2016v2 2016 Version 2 Emissions Modeling Platform
2016v3 2016 Version 3 Emissions Modeling Platform
ARP Acid Rain Program
ADEQ Arizona Department of Environmental Quality
CAA or Act Clean Air Act
CAIR Clean Air Interstate Rule
CBI Confidential Business Information
CFB Circulating Fluidized Bed Units
CFR Code of Federal Regulations
CSAPR Cross-State Air Pollution Rule
DAHS Data Acquisition and Handling System
EAV Equivalent Annualized Values
EGU Electric Generating Unit
EHD Environmental Health Department
EIA Economic Impact Assessment
EPA or the Agency United States Environmental Protection Agency
FIP Federal Implementation Plan
g/hp-hr Grams per horsepower per hour
Group 2 allowances CSAPR NO<INF>X</INF> Ozone Season Group 2
allowances
Group 2 trading program CSAPR NO<INF>X</INF> Ozone Season Group 2
Trading Program
Group 3 allowances CSAPR NO<INF>X</INF> Ozone Season Group 3
allowances
Group 3 Trading Program CSAPR NO<INF>X</INF> Ozone Season Group 3
Trading Program
ICR Information Collection Request
IPM Integrated Planning Model
LNB Low-NO<INF>X</INF> Burners
MJO Multi-Jurisdictional Organization
MOVES Motor Vehicle Emission Simulator
MW Megawatts
NAA Nonattainment Area
NAAQS National Ambient Air Quality Standards
NAICS North American Industry Classification System

[[Page 12667]]

NMED New Mexico Environment Department
Non-EGU Non-Electric Generating Unit
NODA Notice of Data Availability
NO<INF>X</INF> Nitrogen Oxides
NSCR Non-Selective Catalytic Reduction
OMB United States Office of Management and Budget
PBI Proprietary Business Information
ppb parts per billion
ppm parts per million
ppmvd parts per million by volume, dry
PRA Paperwork Reduction Act
PV Present Value
RFA Regulatory Flexibility Act
RIA Regulatory Impact Analysis
RICE Reciprocating Internal Combustion Engines
SC-CO2 Social Cost of Carbon
SCR Selective Catalytic Reduction
SIL Significant Impact Level
SIP State Implementation Plan
SNCR Selective Non-Catalytic Reduction
SO<INF>2</INF> Sulfur Dioxide
TAS Treatment as State
TDEC Tennessee Department of Environmental Control
TSD Technical Support Document
tpy tons per year
UMRA Unfunded Mandates Reform Act
Violating-Monitor Receptors Violating-Monitor Maintenance-Only
Receptors
VOCs Volatile Organic Compounds

Table of Contents

I. Executive Summary
A. Purpose of the Regulatory Action
B. Costs and Benefits
II. General Information
A. Does this action apply to me?
B. What action is the Agency taking?
C. What is the Agency's authority for taking this action?
D. Severability
E. Public Participation
1. Written Comments
2. Participation in Virtual Public Hearing
III. Background
A. Description of Statutory Background
B. Description of the EPA's 4-Step Interstate Transport
Regulatory Process
C. The EPA's Ozone Transport Modeling
D. The EPA's Approach To Evaluating Interstate Transport for the
2015 Ozone NAAQS
1. Selection of Analytic Years
2. Step 1 of the 4-Step Interstate Transport Framework
3. Step 2 of the 4-Step Interstate Transport Framework
4. Step 3 of the 4-Step Interstate Transport Framework
5. Step 4 of the 4-Step Interstate Transport Framework
IV. SIP Submissions Addressing Interstate Transport of Air Pollution
for the 2015 8-Hour Ozone NAAQS
A. SIP Summaries
1. Arizona
Prior Notices Related to Arizona's SIP Submission
2. New Mexico
a. Information Provided by New Mexico Regarding Step 1
b. Information Provided by New Mexico Regarding Step 2
c. New Mexico Letter
3. Tennessee
Prior Notices Related to Tennessee's SIP Submission
B. EPA Evaluation
1. Arizona
a. Evaluation of Information Provided by Arizona Regarding Steps
1 and 2
b. Results of the EPA's Step 1 and Step 2 Modeling and Findings
for Arizona
c. Evaluation of Information Provided Regarding Step 3
d. Conclusion
2. New Mexico
a. Evaluation of Information Provided by New Mexico Regarding
Step 1
b. Evaluation of Information Provided by New Mexico Regarding
Step 2
c. Results of the EPA's Step 1 and Step 2 Modeling and Findings
for New Mexico
d. Evaluation of Information Provided Regarding Step 3
e. NMED's July 2023 Letter
f. Conclusion
3. Tennessee
a. Evaluation of Information Provided by Tennessee Regarding
Step 1
b. Evaluation of Information Provided by Tennessee Regarding
Step 2
c. Results of the EPA's Step 1 and Step 2 Modeling and Findings
for Tennessee
d. Evaluation of Information Provided for Tenessee Regarding
Step 3
e. Conclusion
C. Proposed SIP Action
V. Other Clean Air Act Authorities for This Action
A. Correction of the EPA's Determination Regarding SIP
Submissions From Iowa and Kansas and Its Impact on the EPA's FIP
Authority for Iowa and Kansas
B. Application of Rule in Indian Country and Necessary or
Appropriate Finding
VI. Quantifying Upwind-State NO<INF>X</INF> Emissions Reduction
Potential To Reduce Interstate Ozone Transport for the 2015 Ozone
NAAQS
A. Summary of Multi-Factor Test
B. Summary of Control Stringency Levels
1. EGUs
2. Non-EGUs
C. Control Stringencies Represented by Cost Threshold ($ per
Ton) and Corresponding Emissions Reductions
1. EGUs
2. Non-EGUs
D. Assessing Cost, EGU and Non-EGU NO<INF>X</INF> Reductions,
and Air Quality
1. EGU and Non-EGU Cost and Emissions Reductions Assessment
2. Step 3 Air Quality Assessment Methodology
3. Results for Combined EGU and Non-EGU Air Quality Assessment
4. Conclusions
VII. Regulatory Requirements and Implementation
A. Regulatory Requirements for EGUs
1. Applicability and Tentative Identification of Newly Affected
Units
2. Preset State Emissions Budgets
3. Unit-Level Allowance Allocations
4. Timing Adjustments for Certain Trading Program Provisions
5. Creation of an Additional Group 3 Allowance Bank for the 2025
Control Period and Adjustment to Bank Recalibration for the 2025
Control Period
B. Regulatory Requirements for Non-EGUs
C. Submitting a SIP
1. SIP Option To Modify Allocations for 2026 Under EGU Trading
Program
2. SIP Option To Modify Allocations for 2027 and Beyond Under
EGU Trading Program
3. SIP Option To Replace the Federal EGU Trading Program With an
Integrated State EGU Trading Program
4. SIP Revisions That Do Not Use the Trading Program
5. SIP Revision Requirements for Non-EGU or Industrial Source
Control Requirements
D. Title V Permitting
VIII. Environmental Justice Considerations, Implications and
Outreach
A. Environmental Justice
1. EGU Proximity Assessment
2. Non-EGU Proximity Assessment
B. Outreach
IX. Costs, Benefits, and Other Impacts of the Proposed Rule
X. Summary of Proposed Changes to Existing Regulatory Text
A. Amendments To Apply the Federal Good Neighbor Plan's
Requirements to EGUs in Additional States
B. Amendments To Apply the Federal Good Neighbor Plan's
Requirements to Non-EGUs in Additional States
C. Technical Corrections and Clarifications to Previously
Finalized Regulatory Text
XI. Statutory and Executive Order Reviews
A. Executive Order 12866: Regulatory Planning and Review and
Executive Order 14094: Modernizing Regulatory Review
B. Paperwork Reduction Act (PRA)
1. Information Collection Request for Electric Generating Units
2. Information Collection Request for Non-Electric Generating
Units
C. Regulatory Flexibility Act (RFA)
D. Unfunded Mandates Reform Act (UMRA)
E. Executive Order 13132: Federalism
F. Executive Order 13175: Consultation and Coordination With
Indian Tribal Governments
G. Executive Order 13045: Protection of Children From
Environmental Health Risks and Safety Risks
H. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution or Use
I. National Technology Transfer and Advancement Act
J. Executive Order 12898: Federal Actions To Address
Environmental Justice in Minority Populations and Low-Income
Populations and Executive Order 14096: Revitalizing Our Nation's
Commitment to Environmental Justice for All
K. Determinations Under CAA Section 307(b)(1) and (d)

I. Executive Summary

This proposed rule would resolve the interstate transport
obligations of five states under CAA section 110(a)(2)(D)(i)(I),
referred to as the

[[Page 12668]]

``good neighbor provision'' or the ``interstate transport provision''
of the Act, for the 2015 ozone NAAQS. On October 1, 2015, the EPA
revised the primary and secondary 8-hour standards for ozone to 70
parts per billion (ppb).\1\ States were required to provide ozone
infrastructure SIP submissions to fulfill interstate transport
obligations for the 2015 ozone NAAQS by October 1, 2018.
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\1\ See 80 FR 65291 (October 26, 2015).
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The EPA proposes to make a finding that interstate transport of
ozone precursor emissions from five upwind states (Arizona, Iowa,
Kansas, New Mexico, and Tennessee) is interfering with maintenance of
the 2015 ozone NAAQS in other states. The EPA is withdrawing its
previous proposed actions on SIP submissions from Arizona and
Tennessee,\2\ proposing to partially approve and partially disapprove
good neighbor SIP submissions from Arizona, New Mexico, and Tennessee,
and to error-correct its prior good neighbor SIP approval actions for
Iowa and Kansas to partial disapprovals.\3\ To fulfill the EPA's
responsibility to ensure that states meet their interstate transport
obligations as expeditiously as practicable to meet attainment
deadlines for the 2015 ozone NAAQS, the EPA also proposes FIP
requirements for these five states to prohibit the emissions that
interfere with maintenance of the NAAQS in other states. For states
covered in this action, the EPA proposes to define new ozone season
nitrogen oxides (NO<INF>X</INF>) emissions performance obligations for
Electric Generating Unit (EGU) sources and to fulfill those obligations
by implementing an allowance-based ozone season trading program
beginning in 2025. The EPA is also proposing to establish emissions
limitations beginning in 2027 for certain other industrial stationary
sources (referred to generally as ``non-Electric Generating Units''
(non-EGUs) in Arizona. Taken together, these strategies will fully
resolve the covered states' good neighbor obligations for the 2015
ozone NAAQS.
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\2\ See 87 FR 37776 (June 24, 2022). (The EPA's proposed
approval of Arizona's SIP); and 87 FR 9545 (February 22, 2022) (The
EPA's proposed disapproval of Tennessee's SIP).
\3\ See 87 FR 22463 (April 15, 2022) (Iowa); and 87 FR 19390
(April 4, 2022) (Kansas).
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The EPA proposes to implement the necessary emissions reductions as
follows. The proposed FIP requirements establish ozone season
NO<INF>X</INF> emissions budgets for EGUs in Arizona, Iowa, Kansas, New
Mexico, and Tennessee and require EGUs in these states to participate
in the revised version of the Cross-State Air Pollution Rule (CSAPR)
NO<INF>X</INF> Ozone Season Group 3 Trading Program established in the
final Federal Good Neighbor Plan Rule.\4\ For states currently covered
by the CSAPR NO<INF>X</INF> Ozone Season Group 2 Trading Program (i.e.,
Iowa, Kansas, Tennessee), the EPA proposes to amend existing FIPs to
transition EGU sources in these states from the Group 2 trading program
to the revised Group 3 trading program, beginning with the 2025 ozone
season. The EPA proposes to issue new FIPs for Arizona and New Mexico,
which are not currently covered by any CSAPR NO<INF>X</INF> ozone
season trading program. Under CAA section 301(d)(4), the EPA also
proposes to extend the FIP requirements to apply in Indian country
located within the geographical boundaries of the states included in
this proposal, including Indian reservation lands and other areas of
Indian country over which the EPA or a tribe has demonstrated that a
tribe has jurisdiction.
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\4\ Federal ``Good Neighbor Plan'' for the 2015 Ozone National
Ambient Air Quality Standards, 88 FR 36654 (June 5, 2023).
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The timeframes for implementation of these emissions-reduction
strategies are, in the EPA's judgment, as expeditious as practicable
and aligned to the extent possible with the attainment schedule for
downwind areas in nonattainment of the 2015 ozone NAAQS. As discussed
in section VI. of this document, the EPA proposes to find that the 2025
ozone season is as expeditious as practicable to implement emissions
reductions associated with near-term emissions control strategies at
EGUs, and the 2027 ozone season is as expeditious as practicable to
implement emissions reductions associated with new post-combustion
control installations at EGUs as well as from installation of new
pollution controls at non-EGUs.
As identified in section VI. of this document, the EPA proposes to
find that, because Iowa, Kansas, New Mexico, and Tennessee are not
linked to receptors in the 2026 ozone season, the near-term EGU
emissions-control strategy is sufficient to eliminate these states'
interference with maintenance of the NAAQS in other states. Because
Arizona remains linked to receptors through the 2026 ozone season, the
EPA proposes to find that additional NO<INF>X</INF> emissions from EGUs
and NO<INF>X</INF> emissions from non-EGU sources in Arizona are
interfering with maintenance of the 2015 ozone NAAQS in other states
and that additional cost-effective controls for NO<INF>X</INF>
emissions reductions are available from EGUs and in certain industries
that would result in meaningful air quality improvements at downwind
receptors. Thus, in addition to more stringent EGU emissions budgets
for Arizona beginning in 2027, the EPA proposes to require emissions
limitations beginning in 2027 for non-EGUs located within Arizona. The
Federal Good Neighbor Plan established NO<INF>X</INF> emissions
limitations during the ozone season for the following unit types for
sources in non-EGU industries: reciprocating internal combustion
engines (RICE) in Pipeline Transportation of Natural Gas; kilns in
Cement and Cement Product Manufacturing; boilers and reheat furnaces in
Iron and Steel Mills and Ferroalloy Manufacturing; furnaces in Glass
and Glass Product Manufacturing; boilers in Basic Chemical
Manufacturing, Metal Ore Mining, Petroleum and Coal Products
Manufacturing, and Pulp, Paper, and Paperboard Mills and combustors and
incinerators in Solid Waste Combustors and Incinerators.\5\
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\5\ 88 FR 36654, at 36817.
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A. Purpose of the Regulatory Action

In this supplemental notice of proposed rulemaking, the EPA is
providing an opportunity for public comment on its proposed conclusion
that SIP submissions from Arizona, New Mexico, and Tennessee do not
contain the necessary provisions to prohibit emissions from sources
within their states from interfering with maintenance of the 2015 ozone
NAAQS in downwind areas. The EPA also proposes to find it necessary to
issue an error correction under the authority of CAA section 110(k)(6)
of its previous approval actions for Kansas and Iowa and proposes to
partially disapprove these states' interstate transport submissions. In
addition, the EPA proposes to conclude that emissions from sources in
Arizona, Iowa, Kansas, New Mexico, and Tennessee interfere with
maintenance of the 2015 ozone NAAQS in other states, and therefore the
EPA is proposing FIPs to address these states' transport obligations
through expanding the coverage of the Federal Good Neighbor Plan Rule
\6\ finalized on March 15, 2023. The EPA is proposing to implement the
ozone season NO<INF>X</INF> trading program requirements for EGU
sources in the Federal Good Neighbor Plan as the FIPs for Arizona,
Iowa, Kansas, New Mexico, and Tennessee and the emissions limits for
non-EGU (industrial) sources in the Federal Good Neighbor Plan as the
FIP for Arizona. These control strategies, if finalized,

[[Page 12669]]

will prohibit the emissions from these five states identified as
interfering with maintenance of the 2015 ozone NAAQS in other states.
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\6\ Federal ``Good Neighbor Plan'' for the 2015 Ozone National
Ambient Air Quality Standards, 88 FR 36654 (June 5, 2023).
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The EPA proposes to extend the coverage of the Federal Good
Neighbor Plan to these five additional states based on the same data
and analyses contained in that rule. In the Federal Good Neighbor Plan,
the EPA identified and finalized FIPs for 23 states with emissions that
significantly contribute to nonattainment or interfere with maintenance
of the 2015 ozone NAAQS in other states. The EPA used the same set of
nationwide air quality modeling, air quality monitoring data, and
technical analysis of emissions control opportunities in defining good
neighbor obligations for all states covered in that action. Consistent
with the application of the EPA's 4-step interstate transport
framework, which has been used in prior good neighbor rules like the
CSAPR and upheld by the federal courts, the EPA applied emissions
control requirements on a uniform basis across those states based on
that record.
The EPA maintains that it is reasonable, appropriate, and
consistent with the EPA's prior decisions to extend the Federal Good
Neighbor Plan's contribution analysis and emissions control
requirements to include the five states covered in this action. The EPA
has not identified any factors unique to these five states that would
warrant applying a different approach. These five states were not
addressed in the Federal Good Neighbor Plan because the EPA was not
positioned to take final rulemaking action to disapprove SIPs, error
correct prior approvals to disapprovals, or promulgate FIPs for these
states at that time. To maintain consistency across all states such
that the allocation of responsibility for eliminating states'
significant contribution and interference with maintenance of the NAAQS
in downwind states is done on an equitable basis, the EPA proposes to
apply to five additional states the nationwide findings and
determinations contained in the Federal Good Neighbor Plan as to the
original 23 states which will, if finalized, eliminate these additional
states' significant contribution. Thus, in this action the EPA proposes
to apply to these five states its air quality modeling and contribution
information for the analytical years 2023 and 2026 at Steps 1 and 2,
its analysis of emissions control opportunities for EGUs and non-EGUs
and determinations of stringency, including overcontrol analysis, at
Step 3, and its implementation programs at Step 4. The technical
materials and record-based findings that underlie these determinations
are all contained in the Federal Good Neighbor Plan record. The scope
of this rulemaking is limited to the application of that record to
these five additional states.
Thus, in this document, the EPA is taking comment only on (a) the
EPA's proposed conclusions that SIP submissions from Arizona, New
Mexico, and Tennessee do not contain the necessary provisions to
prohibit emissions from sources within their respective states from
interfering with maintenance of the 2015 ozone standard, (b) the EPA's
proposed conclusion that the Agency must error correct its final rules
approving SIPs from Iowa and Kansas to partial disapprovals, (c) the
EPA's proposed conclusions that the five states identified above have
emissions that interfere with maintenance of the 2015 ozone NAAQS in
other states, and (d) the EPA's proposed decision to apply the Federal
Good Neighbor Plan emissions-control programs as the FIP requirements
to address these emissions in these five states.
Additionally, the EPA has updated its analysis of air quality
improvements at Step 3 and demonstration that there is no overcontrol
resulting from the inclusion of these five additional states in the
Federal Good Neighbor Plan. The EPA proposes that the 2025 and 2027
ozone seasons represent appropriate compliance start-dates for these
states, affording sufficient lead time for sources to plan for
compliance from the standpoint of when this rulemaking will likely be
finalized, which the EPA currently anticipates will be in the summer of
2024. These proposed findings are within the scope of this rulemaking
and open for public comment.
The EPA is not reopening any determinations made in the Federal
Good Neighbor Plan as to the 23 states covered in that action. Nor is
the EPA taking comment on any aspect of the Federal Good Neighbor Plan,
except to the extent of its application to these five states. In
general, the record for the Federal Good Neighbor Plan Rule contains
information at each step of the 4-step interstate transport framework
that can be applied to these five states. Thus, the identification of
receptors to which these five states are linked and the level of
contribution from these states to those receptors is based on the same
analytical findings using the air quality modeling and monitoring data
contained in the Federal Good Neighbor Plan. In addition, the analysis
underlying the EPA's determinations at Step 3 as to EGUs and non-EGUs
and the appropriate degree of emissions-control stringency needed to
eliminate significant contribution and interference with maintenance
likewise was conducted on a region-wide basis, and in the EPA's view is
reasonably applied to the emissions sources in these five states. The
emissions-control requirements were established on a uniform basis for
each particular industry covered in the Federal Good Neighbor Plan, and
do not vary by State (except to the extent that states not linked in
2026 are not subject to the requirements that onset in 2026 and
California's EGUs are not subject to the EGU trading program). Based on
these findings, these programs should be extended to these five states.
This is reasonable and indeed necessary to ensure consistency and
equitable treatment across all states in addressing the nationwide
problem of interstate ozone pollution for the 2015 ozone NAAQS. See EME
Homer City v. EPA, 472 U.S. 572, 519, 524 (2014). This is also
consistent with the EPA's practice throughout the history of
implementing the good neighbor provision for other NAAQS. For instance,
using the final analysis in the original CSAPR rulemaking, the EPA soon
after conducted rulemaking to include five additional states in the
CSAPR trading programs. See 76 FR 80760 (December 27, 2011). Thus, for
the same reasons, the EPA proposes to find it reasonable and
appropriate to extend the uniform set of findings and determinations
made in the Federal Good Neighbor Plan to these five additional states
for the 2015 ozone NAAQS. The EPA is not aware of any information with
respect to these states that would justify a deviation from the same
set of findings and requirements that already have been made for the 23
states covered in the Federal Good Neighbor Plan with respect to these
same obligations.
Finally, this action also includes proposed technical corrections
to the existing regulatory text finalized in the Federal Good Neighbor
Plan.

B. Costs and Benefits

Table I.B-1 summarizes the key results of the cost-benefit analysis
that was prepared for this proposed rule. Table I.B-1 presents
estimates of the present values (PV) and equivalent annualized values
(EAV), calculated using discount rates of 3 and 7 percent as
recommended by the Office of Management and Budget's (OMB) Circular A-
4, of the health and climate benefits, compliance costs, and net
benefits of the proposed rule, in 2016 dollars, discounted to 2023. The
estimated monetized net benefits are the

[[Page 12670]]

estimated monetized benefits minus the estimated monetized costs of the
proposed rule. These results present an incomplete overview of the
effects of the rule because important categories of benefits were not
monetized (e.g., ecosystem effects, visibility impairment, and water
quality improvements) and are therefore not reflected in the cost-
benefit tables. The EPA anticipates that taking non-monetized effects
into account would show the proposed rule to be more net beneficial
than this table reflects.

Table I.B-1--Estimated Monetized Health and Climate Benefits, Compliance Costs, and Net Benefits of the Proposed
Rule, 2025 Through 2044
[Millions 2016$, discounted to 2023] \a\
----------------------------------------------------------------------------------------------------------------
3% Discount rate 7% Discount rate
----------------------------------------------------------------------------------------------------------------
Present Value:
Health Benefits \b\............ $330 and $1,900...................... $210 and $1,200.
Climate Benefits \c\........... $9.3................................. $9.3.
Compliance Costs \d\........... $67.................................. $45.
----------------------------------------------------------------------------
Net Benefits............... $270 and $1,800...................... $180 and $1,100.
Equivalent Annualized Value:
Health Benefits................ $22 and $130......................... $20 and $110.
Climate Benefits............... $0.6................................. $0.6.
Compliance Costs............... $4.5................................. $4.2.
----------------------------------------------------------------------------
Net Benefits............... $18 and $120......................... $17 and $110.
----------------------------------------------------------------------------------------------------------------
\a\ Rows may not appear to add correctly due to rounding. The EPA used 2016 dollars in both the proposal and
final Revised CSAPR Update Regulatory Impact Analysis (RIA), as well as the proposal and final Federal Good
Neighbor Plan RIA; to be consistent with those recent actions we continued to use 2016 dollars as the dollar
year for presenting costs and benefits.
\b\ The annualized present value of costs and benefits are calculated over a 20-year period from 2025 to 2044.
Monetized benefits include those related to public health associated with reductions in ozone and PM2.5
concentrations. The health benefits are associated with two alternative estimates of the number of premature
deaths and are presented at real discount rates of 3 and 7 percent. Several categories of benefits remain
unmonetized and are thus not reflected in the table.
\c\ Climate benefits are calculated using four different estimates of the social cost of carbon (SC-CO2) (model
average at 2.5 percent, 3 percent, and 5 percent discount rates; 95th percentile at 3 percent discount rate).
For presentational purposes in this table, the climate benefits associated with the average SC-CO2 at a 3-
percent discount rate are used in the columns displaying results of other costs and benefits that are
discounted at either a 3-percent or 7-percent discount rate.
\d\ The costs presented in this table are consistent with the costs presented in section 3 of the Economic
Impact Assessment (EIA). To estimate these annualized costs for EGUs, the EPA uses a conventional and widely
accepted approach that applies a capital recovery factor multiplier to capital investments and adds that to
the annual incremental operating expenses. Costs were calculated using a 3.75 percent real discount rate
consistent with the rate used in the Integrated Planning Model's (IPM) objective function for cost-
minimization. For further information on the discount rate use, please see section 3 of the EIA.

As shown in Table I.B-1, the PV of the monetized health benefits,
associated with reductions in ozone and PM<INF>2.5</INF> of this
proposed rule, discounted at a 3-percent discount rate, is estimated to
be about $330 and $1,900 million, with an EAV of about $22 and $130
million. At a 7-percent discount rate, the PV of the monetized health
benefits is estimated to be $210 and $1,200 million, with an EAV of
about $20 and $110 million. The PV of the monetized climate benefits,
associated with reductions in greenhouse gas (GHG) emissions, of this
proposed rule, discounted at a 3-percent discount rate, is estimated to
be about $9.3 million, with an EAV of about $0.6 million. The PV of the
monetized compliance costs, discounted at a 3-percent rate, is
estimated to be about $67 million, with an EAV of about $4.5 million.
At a 7-percent discount rate, the PV of the compliance costs is
estimated to be about $45 million, with an EAV of about $4.2 million.

II. General Information

A. Does this action apply to me?

This supplemental proposed rule affects EGU and non-EGU sources,
and regulates the groups identified in Table II.A-1, along with their
North American Industry Classification System (NAICS) code.

Table II.A-1--Regulated Groups
------------------------------------------------------------------------
Industry group NAICS
------------------------------------------------------------------------
Fossil fuel-fired electric power generation............. 221112
Pipeline Transportation of Natural Gas.................. 4862
Metal Ore Mining........................................ 2122
Cement and Concrete Product Manufacturing............... 3273
Iron and Steel Mills and Ferroalloy Manufacturing....... 3311
Glass and Glass Product Manufacturing................... 3272
Basic Chemical Manufacturing............................ 3251
Petroleum and Coal Products Manufacturing............... 3241
Pulp, Paper, and Paperboard Mills....................... 3221
Solid Waste Combustors and Incinerators................. 562213
------------------------------------------------------------------------

This table is not intended to be exhaustive, but rather provides a
guide for readers regarding entities likely to be regulated by this
proposed rule. This table lists the types of entities that the EPA is
now aware could potentially be

[[Page 12671]]

regulated by this proposed rule. Other types of entities not listed in
the table could also be regulated. To determine whether a particular
entity is regulated by this proposed rule, you should carefully examine
the applicability criteria found in 40 CFR 97.1004 (EGUs) or 40 CFR
52.40(c), 52.41(b), 52.42(b), 52.43(b), 52.44(b), 52.45(b), and
52.46(b) (non-EGUs). If you have questions regarding the applicability
of this proposed rule to a particular entity, consult the person listed
in the FOR FURTHER INFORMATION CONTACT section.

B. What action is the Agency taking?

The EPA evaluated whether interstate ozone transport emissions from
upwind states are significantly contributing to nonattainment, or
interfering with maintenance, of the 2015 ozone NAAQS in any downwind
State using the same 4-step interstate transport framework that was
developed in previous ozone transport rulemakings. In its previous
action, the Federal Good Neighbor Plan, the EPA found that sources in
23 states had obligations to eliminate their significant contribution
to nonattainment and interference with maintenance in downwind
areas.\7\ In this proposed rule, the EPA is proposing to apply that
same analysis to find that emissions reductions are required from EGU
sources in the additional states of Arizona, Iowa, Kansas, New Mexico,
and Tennessee and from non-EGU sources in Arizona. The EPA proposes to
ensure that these NO<INF>X</INF> emissions reductions are achieved by
issuing FIP requirements for these five states.
---------------------------------------------------------------------------

\7\ 88 FR 36654 (June 5, 2023).
---------------------------------------------------------------------------

In this rule, the EPA is proposing to find that SIP submissions
from Arizona, New Mexico, and Tennessee lack adequate provisions to
ensure sources and other emissions activity in their states are not
interfering with maintenance of the 2015 ozone NAAQS in other states.
The EPA is also proposing to error correct its previous actions on SIP
submissions from Iowa and Kansas to partial disapprovals for the same
reason.\8\
---------------------------------------------------------------------------

\8\ 87 FR 22463 (April 15, 2022) (Iowa); 87 FR 19390 (April 4,
2022) (Kansas).
---------------------------------------------------------------------------

In this same action, the EPA proposes FIP requirements for these
five states. The EPA is proposing to incorporate Arizona, Iowa, Kansas,
New Mexico, and Tennessee into the existing CSAPR NO<INF>X</INF> Ozone
Season Group 3 Trading Program established in the Federal Good Neighbor
Plan, beginning in the 2025 ozone season. EGUs in states not currently
covered by any CSAPR trading program for seasonal NO<INF>X</INF>
emissions--Arizona and New Mexico--will be added to the CSAPR
NO<INF>X</INF> Ozone Season Group 3 Trading Program under this rule.
EGUs in Iowa, Kansas, and Tennessee will transition from the CSAPR
NO<INF>X</INF> Ozone Season Group 2 Trading Program to the CSAPR
NO<INF>X</INF> Ozone Season Group 3 Trading Program. The EPA is
establishing a control stringency level reflecting optimization of
existing post-combustion controls and installation of state-of-the-art
combustion controls on certain covered EGU sources in the emissions
budgets beginning in the 2025 ozone season. In addition, for Arizona,
the EPA is establishing a control stringency level reflecting
installation of new Selective Catalytic Reduction (SCR) or Selective
Non-Catalytic Reduction (SNCR) controls on certain covered EGU sources
in its emissions budgets beginning with the 2027 ozone season.
Consistent with the emissions limitations established for non-EGU
sources in the Federal Good Neighbor Plan, this supplemental action
proposes to establish emissions limitations for new and existing non-
EGU sources in Arizona beginning with the 2027 ozone season. The
Federal Good Neighbor Plan established control requirements for the
following unit types in non-EGU industries: RICE in Pipeline
Transportation of Natural Gas; kilns in Cement and Cement Product
Manufacturing; reheat furnaces in Iron and Steel Mills and Ferroalloy
Manufacturing; furnaces in Glass and Glass Product Manufacturing;
boilers in Iron and Steel Mills and Ferroalloy Manufacturing, Metal Ore
Mining, Basic Chemical Manufacturing, Petroleum and Coal Products
Manufacturing, and Pulp, Paper, and Paperboard Mills; and combustors
and incinerators in Solid Waste Combustors and Incinerators. See Table
II.A-1 in this document for a list of NAICS codes for the relevant
industries.
In accordance with the requirements of the good neighbor provision,
CAA section 110(a)(2)(D)(i)(I), this proposed rule reduces the
transport of ozone and ozone precursors from emissions in upwind states
to downwind areas to protect human health and the environment from
negative health impacts associated with acute and chronic exposure to
ozone. Ozone exposure is also associated with negative effects on
ecosystems. Additional information on the air quality issues addressed
by this proposed rule is included in section IX. of this document.

C. What is the Agency's authority for taking this action?

The statutory authority for this proposed action is provided by the
CAA as amended (42 U.S.C. 7401 et seq.). Specifically, sections 110 and
301 of the CAA provide the primary statutory underpinnings for this
action. The most relevant portions of CAA section 110 are subsections
110(a)(1), 110(a)(2) (including 110(a)(2)(D)(i)(I)), 110(k)(2),
110(k)(3), 110(k)(6), and 110(c)(1).
CAA section 110(a)(1) provides that states must make SIP
submissions ``within 3 years (or such shorter period as the
Administrator may prescribe) after the promulgation of a national
primary ambient air quality standard (or any revision thereof),'' and
that these SIP submissions are to provide for the ``implementation,
maintenance, and enforcement'' of such NAAQS.\9\ The statute directly
imposes on states the duty to make these SIP submissions, and the
requirement to make the submissions is not conditioned upon the EPA
taking any action other than promulgating a new or revised NAAQS.\10\
---------------------------------------------------------------------------

\9\ 42 U.S.C. 7410(a)(1).
\10\ See EPA v. EME Homer City Generation, L.P., 572 U.S. 489,
509-10 (2014).
---------------------------------------------------------------------------

The EPA has historically referred to SIP submissions made for the
purpose of satisfying the applicable requirements of CAA sections
110(a)(1) and 110(a)(2) as ``infrastructure SIP'' or ``iSIP''
submissions.'' CAA section 110(a)(1) addresses the timing and general
requirements for iSIP submissions, and CAA section 110(a)(2) provides
more details concerning the required content of these submissions.\11\
It includes a list of specific elements that ``[e]ach such plan'' must
address, including the requirements of the good neighbor provision.\12\
---------------------------------------------------------------------------

\11\ 42 U.S.C. 7410(a)(2).
\12\ The EPA's general approach to infrastructure SIP
submissions is explained in greater detail in individual documents
acting or proposing to act on State infrastructure SIP submissions
and in guidance. See, e.g., Memorandum from Stephen D. Page on
Guidance on Infrastructure State Implementation Plan (SIP) Elements
under Clean Air Act Sections 110(a)(1) and 110(a)(2) (September 13,
2013).
---------------------------------------------------------------------------

CAA section 110(c)(1) requires the Administrator to promulgate a
FIP at any time within 2 years after the Administrator: (1) finds that
a State has failed to make a required SIP submission; (2) finds a SIP
submission to be incomplete pursuant to CAA section 110(k)(1)(C); or
(3) disapproves a SIP submission. This obligation applies unless the
State corrects the deficiency through a SIP revision that

[[Page 12672]]

the Administrator approves before the FIP is promulgated.\13\
---------------------------------------------------------------------------

\13\ 42 U.S.C. 7410(c)(1).
---------------------------------------------------------------------------

CAA section 110(a)(2)(D)(i)(I), also known as the ``good neighbor''
provision, provides the primary basis for this proposed action.\14\ It
requires that each State's SIP include provisions sufficient to
``prohibit[ ], consistent with the provisions of this subchapter, any
source or other type of emissions activity within the State from
emitting any air pollutant in amounts which will--(I) contribute
significantly to nonattainment in, or interfere with maintenance by,
any other State with respect to any [NAAQS].'' \15\ The EPA often
refers to the emissions reduction requirements under this provision as
``good neighbor obligations'' and submissions addressing these
requirements as ``good neighbor SIPs.''
---------------------------------------------------------------------------

\14\ 42 U.S.C. 7410(a)(2)(D)(i)(I).
\15\ Id.
---------------------------------------------------------------------------

Once the EPA promulgates a NAAQS, the EPA must designate areas as
being in ``attainment'' or ``nonattainment'' of the NAAQS, or
``unclassifiable.'' CAA section 107(d).\16\ For ozone, nonattainment is
further split into five classifications based on the severity of the
violation--Marginal, Moderate, Serious, Severe, or Extreme. Higher
classifications provide states with progressively more time to attain
while imposing progressively more stringent control requirements. See
CAA sections 181, 182.\17\ In general, states with nonattainment areas
classified as Moderate or higher must submit plans to the EPA to bring
these areas into attainment according to the statutory schedule in CAA
section 182.\18\ If an area fails to attain the NAAQS by the attainment
date associated with its classification, it is ``bumped up'' to the
next classification, per the requirements in CAA section 181(b).\19\
---------------------------------------------------------------------------

\16\ 42 U.S.C. 7407(d).
\17\ 42 U.S.C. 7511, 7511a.
\18\ 42 U.S.C. 7511a.
\19\ 42 U.S.C. 7511(b).
---------------------------------------------------------------------------

Section 301(a)(1) of the CAA gives the Administrator the general
authority to prescribe such regulations as are necessary to carry out
functions under the Act.\20\ Pursuant to this section, the EPA has
authority to clarify the applicability of CAA requirements and
undertake other rulemaking action as necessary to implement CAA
requirements. CAA section 301 affords the Agency any additional
authority that may be needed to make certain other changes to its
regulations under 40 CFR parts 52 and 97 to effectuate the purposes of
the Act. Such changes are discussed in section X. of this document.
---------------------------------------------------------------------------

\20\ 42 U.S.C. 7601(a)(1).
---------------------------------------------------------------------------

Section 110(k)(6) of the CAA gives the Administrator authority,
without any further submission from a state, to revise certain prior
actions, including actions to approve SIP submissions, upon determining
that those actions were in error.\21\ As discussed further in section
V.A. of this document, the EPA proposes to make error corrections under
CAA section 110(k)(6) with respect to its prior approvals of the 2015
ozone transport SIP submissions from the States of Iowa and Kansas.
---------------------------------------------------------------------------

\21\ 42 U.S.C. 7410(k)(6).
---------------------------------------------------------------------------

Tribes are not required to submit State implementation plans.
However, as explained in the EPA's regulations outlining Tribal CAA
authority, the EPA is authorized to promulgate FIPs for Indian country
as necessary or appropriate to protect air quality if a Tribe does not
submit, and obtain the EPA's approval of, an implementation plan. See
40 CFR 49.11(a); see also CAA section 301(d)(4).\22\ In this action,
the EPA proposes an ``appropriate or necessary'' finding under CAA
section 301(d) and proposes Tribal FIP(s) as necessary to implement the
relevant requirements. This is further discussed in section V.B. of
this document.
---------------------------------------------------------------------------

\22\ 42 U.S.C. 7601(d)(4).
---------------------------------------------------------------------------

D. Severability

The EPA regards this proposal as a complete remedy for the covered
states, which will as expeditiously as practicable implement good
neighbor obligations for the 2015 ozone NAAQS, consistent with the
requirements of the Act. See North Carolina v. EPA, 531 F.3d 896, 911-
12 (D.C. Cir. 2008); Wisconsin v. EPA, 938 F.3d 303, 313- 20 (D.C. Cir.
2019); Maryland v. EPA, 958 F.3d 1185, 1204 (D.C. Cir. 2020); New York
v. EPA, 964 F.3d 1214, 1226 (D.C. Cir. 2020); New York v. EPA, 781 Fed.
App'x 4, 7-8 (D.C. Cir. 2019) (all holding that the EPA must address
good neighbor obligations as expeditiously as practicable and by no
later than the next applicable attainment date). Yet the EPA proposes
that should a court find any discrete aspect of this action, if
finalized, to be invalid, the Agency believes that, like the Federal
Good Neighbor Plan, the remaining aspects of this proposed rule can and
should continue to be implemented to the extent possible, consistent
with law. See 88 FR 36693. In particular, this proposal would
disapprove SIP submissions and promulgate a FIP for each covered state
(and, pursuant to CAA section 301(d), for each area of tribal
jurisdiction within the geographic boundaries of those states). Should
any jurisdiction-specific aspect of the rule, once finalized be found
invalid, the EPA views this rule, if finalized as proposed, as
severable along those state and/or tribal jurisdictional lines, such
that the proposed rule could continue to be implemented as to any
remaining jurisdictions. This action proposes discrete emissions
control requirements for the power sector and for each of nine other
industries. Should any industry-specific aspect of the proposed rule be
found invalid once final, the EPA views this rule as proposed as
severable as between the different industries and different types of
emissions control requirements. This is not intended to be an
exhaustive list of the ways in which the proposed rule may be
severable. In the event any part of the rule, if finalized, is found
invalid, our intention is that the remaining portions should continue
to be implemented consistent with any judicial ruling.\23\
---------------------------------------------------------------------------

\23\ In a declaration dated October 28, 2023, and filed with the
U.S. Supreme Court in State of Ohio et al. v. EPA, No. 23A349, the
Agency, through Joseph Goffman, the Principal Deputy Assistant
Administrator performing delegated duties of Assistant Administrator
for the Office of Air and Radiation, explained in greater detail why
it makes sense as both a technical and legal matter that the Federal
Good Neighbor Plan can continue to be implemented in each covered
state despite preliminary stays of the Plan in other states. This
same reasoning applies with full force with respect to the
additional states that are proposed for inclusion in these programs
in this action. The declaration is included in the docket for this
action.
---------------------------------------------------------------------------

The EPA's conclusion that this proposed rule, upon finalization, is
severable also reflects the important public health and environmental
benefits of this rulemaking in eliminating significant contribution and
to ensure to the greatest extent possible the ability of both upwind
states and downwind states and other relevant stakeholders to be able
to rely on this rule at final in their planning. Cf. Wisconsin, 938
F.3d at 336-37 (``As a general rule, we do not vacate regulations when
doing so would risk significant harm to the public health or the
environment.''); North Carolina v. EPA, 550 F.3d 1176, 1178 (D.C. Cir.
2008) (noting the need to preserve public health benefits); EME Homer
City v. EPA, 795 F.3d 118, 132 (D.C. Cir. 2015) (noting the need to
avoid disruption to emissions trading market that had developed).

E. Public Participation

1. Written Comments
Submit your comments, identified by Docket ID No. EPA-HQ-OAR-2023-
0402, at <a href="https://www.regulations.gov">https://www.regulations.gov</a>. Once submitted, comments cannot
be

[[Page 12673]]

edited or removed from the docket. The EPA may publish any comment
received to its public docket. Do not submit to the EPA's docket at
<a href="https://www.regulations.gov">https://www.regulations.gov</a> any information you consider to be CBI,
Proprietary Business Information (PBI), or other information whose
disclosure is restricted by statute. Multimedia submissions (audio,
video, etc.) must be accompanied by a written comment. The written
comment is considered the official comment and should include
discussion of all points you wish to make. The EPA will generally not
consider comments or comment contents located outside of the primary
submission (i.e., on the web, cloud, or other file sharing system).
Please visit <a href="https://www.epa.gov/dockets/commenting-epa-dockets">https://www.epa.gov/dockets/commenting-epa-dockets</a> for
additional submission methods; the full EPA public comment policy;
information about CBI, PBI, or multimedia submissions; and general
guidance on making effective comments.
2. Participation in Virtual Public Hearing
The EPA will begin pre-registering speakers for the hearing upon
publication of this document in the Federal Register. To register to
speak at the virtual hearing, please use the online registration form
available at <a href="https://www.epa.gov/csapr/csapr-2015-ozone-naaqs">https://www.epa.gov/csapr/csapr-2015-ozone-naaqs</a> or
contact Ms. Pamela Long at (919) 541-0641 and/or <a href="/cdn-cgi/l/email-protection#670b0809004917060a2702170649000811">[email&#160;protected]</a> to
register to speak at the virtual hearing. The last day to pre-register
to speak at the hearing will be 3 working days before the hearing. On
[last working day before the hearing], the EPA will post a general
agenda for the hearing that will list pre-registered speakers in
approximate order at: <a href="https://www.epa.gov/csapr/csapr-2015-ozone-naaqs">https://www.epa.gov/csapr/csapr-2015-ozone-naaqs</a>.
The EPA will make every effort to follow the schedule as closely as
possible on the day of the hearing; however, please plan for the
hearings to run either ahead of schedule or behind schedule.
Additionally, requests to speak will be taken the day of the hearing at
the hearing registration desk. The EPA will make every effort to
accommodate all speakers who arrive and register, although preferences
on speaking times may not be able to be fulfilled. Each commenter will
have 3 minutes to provide oral testimony. The EPA encourages commenters
to provide the EPA with a copy of their oral testimony electronically
by emailing it to Ms. Pamela Long. The EPA also recommends submitting
the text of your oral comments as written comments to the rulemaking
docket.
The EPA may ask clarifying questions during the oral presentations
but will not respond to the presentations at that time. Written
statements and supporting information submitted during the comment
period will be considered with the same weight as oral comments and
supporting information presented at the public hearing.
Please note that any updates made to any aspect of the hearing are
posted online at <a href="https://www.epa.gov/csapr/csapr-2015-ozone-naaqs">https://www.epa.gov/csapr/csapr-2015-ozone-naaqs</a>.
While the EPA expects the hearing to go forward as set forth above,
please monitor our website or contact Ms. Pamela Long at (919) 541-0641
and/or <a href="/cdn-cgi/l/email-protection#630f0c0d044d13020e230613024d040c15">[email&#160;protected]</a> to determine if there are any updates. The EPA
does not intend to publish a document in the Federal Register
announcing updates.
The EPA will not provide audiovisual equipment for presentations
unless the Agency receives special requests in advance. Commenters
should notify Ms. Pamela Long when they pre-register to speak that they
will need specific equipment. If you require the services of an
interpreter or special accommodations such as audio description, please
pre-register for the hearing with Ms. Pamela Long and describe your
needs by [DATE 1 WEEK BEFORE THE PUBLIC HEARING DATE]. The EPA may not
be able to arrange accommodations without advance notice.

III. Background

A. Description of Statutory Background

On October 1, 2015, the EPA promulgated a revision to the ozone
NAAQS (2015 8-hour ozone NAAQS), lowering the level of both the primary
and secondary standards to 0.070 parts per million (ppm) for the 8-hour
standard.\24\ 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 CAA section
110(a)(2).\25\ One of these applicable 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 that SIPs
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). The EPA and states must give
independent significance to Prong 1 and Prong 2 when evaluating
downwind air quality problems under CAA section 110(a)(2)(D)(i)(I).\26\
---------------------------------------------------------------------------

\24\ 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 ppb. For example, 0.070 ppm is equivalent to 70
ppb.
\25\ SIP submissions that are intended to meet the applicable
requirements of CAA section 110(a)(1) and (2) of the CAA are often
referred to as infrastructure SIPs and the applicable elements under
CAA section 110(a)(2) are referred to as infrastructure
requirements.
\26\ See North Carolina v. EPA, 531 F.3d 896, 909-11 (D.C. Cir.
2008).
---------------------------------------------------------------------------

On January 31, 2023, the EPA finalized disapproval of 19 SIP
submissions and partially approved and partially disapproved two SIP
submissions addressing the good neighbor provision for the 2015 ozone
NAAQS. The EPA's evaluation for those actions applied uniform,
nationwide analytical methods, policy judgments, and interpretation
with respect to the same CAA obligations, i.e., implementation of good
neighbor requirements under CAA section 110(a)(2)(D)(i)(I) for the 2015
ozone NAAQS for states across the country. To maintain consistency
across all states in light of the final analytical conclusions reached
in that action and the separate Federal Good Neighbor Plan, the EPA
indicated it would take subsequent action on remaining SIP submissions
addressing interstate transport obligations for the 2015 ozone
NAAQS.\27\ The EPA also indicated it would address previous final
actions on SIP submissions for states where the EPA's final analysis
suggested the State may be significantly contributing to nonattainment
or interfering with maintenance. In the Federal Good Neighbor Plan,
finalized on March 15, 2023, the EPA indicated it would address these
and any outstanding FIP obligations in a future action for these
states, which included the five states included here and Wyoming.\28\
The EPA finalized its approval of the SIP submission from Wyoming on
December 13, 2023.\29\ This action proposes to

[[Page 12674]]

address the five additional remaining SIP submissions and FIP
obligations.
---------------------------------------------------------------------------

\27\ 88 FR 36656.
\28\ 88 FR 36654 at 36656.
\29\ See Air Plan Approval; Wyoming; Interstate Transport of Air
Pollution for the 2015 8-Hour Ozone National Ambient Air Quality
Standards, 88 FR 54998 (August 14, 2023). The EPA signed the final
approval on December 13, 2023. 88 FR 87720 (December 19, 2023).
---------------------------------------------------------------------------

B. Description of the EPA's 4-Step Interstate Transport Regulatory
Process

For decades, when evaluating SIPs and formulating FIPs, EPA has
consistently utilized the 4-step interstate transport framework (or 4-
step framework), which was developed to give meaning to the critical
statutory terms in CAA section 110(a)(2)(D)(i)(I) and to provide a
reasonable organization to the analysis of the complex air quality
challenge of interstate ozone transport. The EPA has addressed the
interstate transport requirements of CAA section 110(a)(2)(D)(i)(I)
with respect to prior NAAQS using the 4-step framework in several
regulatory actions, including the CSAPR, which addressed interstate
transport with respect to the 1997 ozone NAAQS as well as the 1997 and
2006 fine particulate matter standards,\30\ the CSAPR Update \31\ and
the Revised CSAPR Update, both of which addressed the 2008 ozone
NAAQS.\32\ For the 2015 ozone NAAQS, the EPA uses this framework in
evaluating SIP submissions (while considering any alternative
approaches states may propose) and applied this framework in the
Federal Good Neighbor Plan.\33\
---------------------------------------------------------------------------

\30\ See Federal Implementation Plans: Interstate Transport of
Fine Particulate Matter and Ozone and Correction of SIP Approvals,
76 FR 48208 (August 8, 2011).
\31\ Cross-State Air Pollution Rule Update for the 2008 Ozone
NAAQS, 81 FR 74504 (October 26, 2016).
\32\ In 2019, the D.C. Circuit Court of Appeals remanded the
CSAPR Update to the extent it failed to require upwind states to
eliminate their significant contribution by the next applicable
attainment date by which downwind states must come into compliance
with the NAAQS, as established under CAA section 181(a). Wisconsin
v. EPA, 938 F.3d 303, 313 (D.C. 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).
\33\ See 88 FR at 9338; 88 FR at 36671.
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Shaped through the years by input from State air agencies \34\ and
other stakeholders on the EPA's prior interstate transport rulemakings
and SIP submission actions,\35\ as well as a number of court decisions,
the EPA has developed and used the 4-step interstate transport
framework to evaluate 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 to ``contribute'' (i.e., are considered
``linked'') to those receptors and whose emissions 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. EPA does not require states to use
the 4-step framework in good neighbor SIP submissions, but it is a
useful organizational tool that has been upheld by the Supreme Court as
``permissible, workable, and equitable.'' EPA v. EME Homer City
Generation, L.P., 572 U.S. 489, 524 (2014).
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\34\ See 63 FR 57356, 57361 (October 27, 1998).
\35\ In addition to CSAPR rulemakings, other regional
rulemakings addressing ozone transport include the ``NO<INF>X</INF>
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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The general steps of this framework allow for some methodological
variation, and this can be seen in the evolution of the EPA's analytic
process across its prior rulemakings. This also means states have some
flexibility in developing analytic methods within this framework (and
may also attempt to justify an alternative framework altogether). The
four steps of the framework provide a reasonable organization to the
analysis of the complex air quality challenge of interstate ozone
transport. As discussed further throughout this document, the EPA has
organized its evaluation of good neighbor obligations around this
analytical framework (including the specific methodologies within each
step as evolved over the course of the CSAPR rulemakings since 2011).
Where states presented alternative approaches either to the EPA's
methodological approaches within the framework, or organized their
analysis in some manner that differed from it entirely, the EPA has
evaluated those analyses on their merits to determine compliance with
the good neighbor obligation or, in some cases, identified why even if
those approaches were acceptable, the State still does not meet the
good neighbor requirement and therefore does not have an approvable SIP
submission as a whole.

C. The EPA's Ozone Transport Modeling

The EPA has performed nationwide air quality modeling to project
ozone design values that are used in combination with measured data to
identify nonattainment and maintenance receptors at Step 1. To quantify
the contribution of emissions from individual upwind states on 2023 and
2026 ozone design values for the identified downwind nonattainment and
maintenance receptors at Step 2, the EPA has performed nationwide,
state-level ozone source apportionment modeling for 2023 and 2026. The
source apportionment modeling provides contributions to ozone at
receptors from precursor emissions of anthropogenic NO<INF>X</INF> and
volatile organic compounds (VOCs) in individual upwind states. In this
action, the EPA is proposing to apply the air quality modeling and
contribution results that were derived using the 2016v3 modeling and
monitoring data that informed the EPA's Step 1 and Step 2
determinations in the Federal Good Neighbor Plan--inclusive of the
approach for identifying certain addition sites as violating-monitor
maintenance-only receptors based on certified monitoring data and
regulatory design values for 2021 and 2022. This section provides an
overview of the modeling developments that resulted in those analytical
conclusions, which are used here to make good neighbor determinations
for these five additional states.
The EPA released several documents containing projected ozone
design values, contributions, and information relevant to air agencies
for evaluation of interstate transport with respect to the 2015 ozone
NAAQS. First, on January 6, 2017, the 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.\36\ In the NODA, the EPA used the year 2023 as the
analytic year for this preliminary modeling because this year aligns
with the expected attainment year for Moderate ozone nonattainment
areas for the 2015 8-hour ozone NAAQS.\37\ On October 27, 2017, the EPA
released a memorandum (October 2017 memorandum) containing updated
modeling data for 2023, which incorporated changes made in response

[[Page 12675]]

to comments on the NODA, and was intended to provide information to
assist states' efforts to develop SIP submissions to address interstate
transport obligations for the 2008 ozone NAAQS.\38\
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\36\ 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).
\37\ 82 FR at 1735.
\38\ See Information on the Interstate Transport State
Implementation Plan Submissions for the 2008 Ozone National Ambient
Air Quality Standards under Clean Air Act section
110(a)(2)(D)(i)(I), October 27, 2017, available in docket ID No.
EPA-HQ-OAR-2021-0663.
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On March 27, 2018, the 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 ozone NAAQS at
Step 1 of the 4-step interstate transport framework.\39\ 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.\40\ The EPA
subsequently issued two more memoranda in August and October 2018,
providing additional information to states developing interstate
transport SIP submissions for the 2015 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.\41\
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\39\ 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.
\40\ 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.''
\41\ 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, available in docket ID No.
EPA-HQ-OAR-2021-0663.
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Following the release of the modeling data shared in the March 2018
memorandum, the EPA performed updated modeling using a 2016 base year
emissions modeling platform (i.e., 2016 Version 1 Emissions Platform
Modeling, or ``2016v1''). This emissions platform was developed under
the EPA/Multi-Jurisdictional Organization (MJO)/state collaborative
project.\42\ This collaborative project was a multi-year joint effort
by the EPA, MJOs, and states to develop a new, more recent emissions
platform for use by the EPA and states in regulatory modeling as an
improvement over the dated 2011-based platform that the EPA had used to
project ozone design values and contribution data provided in the 2017
and 2018 memoranda. The EPA used the 2016v1 emissions to project ozone
design values and contributions for 2023. On October 30, 2020, in the
Notice of Proposed Rulemaking for the Revised CSAPR Update, the EPA
released and accepted public comment on 2023 modeling that used the
2016v1 emissions platform.\43\ Although the Revised CSAPR Update
addressed transport for the 2008 ozone NAAQS, the projected design
values and contributions from the 2016v1 platform were also useful for
identifying downwind ozone problems and linkages with respect to the
2015 ozone NAAQS.\44\
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\42\ The results of this modeling, as well as the underlying
modeling files, are included in docket ID No. EPA-HQ-OAR-2021-0663.
The 2016v1 emissions modeling technical support document is
available in Docket ID No. EPA-HQ-OAR-2020-0272-0187. Both dockets
are available at <a href="https://www.regulations.gov">https://www.regulations.gov</a>.
\43\ See 85 FR 68964, 68981.
\44\ See the Air Quality Modeling Technical Support Document for
the Final Revised Cross-State Air Pollution Rule Update, included in
the Headquarters docket ID No. EPA-HQ-OAR-2021-0663.
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Following the final Revised CSAPR Update, the EPA made further
updates to the 2016-based emissions platform to include updated onroad
mobile emissions from Version 3 of the EPA's Motor Vehicle Emission
Simulator (MOVES) model (MOVES3) \45\ and updated emissions projections
for EGUs that reflected the emissions reductions from the Revised CSAPR
Update, recent information on plant closures, and other inventory
improvements. The EPA published these emissions inventories on its
website in September of 2021 and invited initial feedback from states
and other interested stakeholders.\46\ The construct of the updated
emissions platform, (i.e., 2016 Version 2 Emissions Platform Modeling,
or ``2016v2''), is described in the ``Technical Support Document (TSD):
Preparation of Emissions Inventories for the 2016v2 North American
Emissions Modeling Platform,'' hereafter known as the 2016v2 Emissions
Modeling TSD, and is included in Docket No. EPA-HQ-OAR-2021-0663. The
EPA performed air quality modeling using the 2016v2 emissions to
provide projections of ozone design values and contributions in 2023
and 2026 that reflect the effects on air quality of the 2016v2
emissions platform. The EPA used the results of the 2016v2 modeling to
inform proposed and final actions on 2015 ozone NAAQS good neighbor
obligations for Iowa and Kansas.\47\
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\45\ Additional details and documentation related to the MOVES3
model can be found at <a href="https://www.epa.gov/moves/latest-version-motor-vehicle-emission-simulator-moves">https://www.epa.gov/moves/latest-version-motor-vehicle-emission-simulator-moves</a>.
\46\ <a href="https://www.epa.gov/air-emissions-modeling/2016v2-platform">https://www.epa.gov/air-emissions-modeling/2016v2-platform</a>.
\47\ The EPA was obligated by consent-decree deadline to
finalize its action for Iowa and Kansas by April 30, 2022, and was
unable to consider or incorporate the later comments received on the
2016v2 modeling that were used to inform the 2016v3 modeling
informing the final Disapproval action and final Federal Good
Neighbor Plan in early 2023.
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The EPA also used the 2016v2 emissions inventories and modeling to
support proposed actions for several states, including the EPA's
previous proposals on Arizona and Tennesse, as well as the proposed
Federal Good Neighbor Plan. In response to comments received for these
rulemakings, the EPA updated the 2016v2 inventories and model design to
construct another emissions platform (i.e., 2016 Version 3 Emissions
Platform Modeling, or ``2016v3''), which was used to update the air
quality modeling. The EPA used this updated modeling to inform a final
rulemaking taking final action on 21 interstate transport SIP
submissions for the 2015 ozone NAAQS and to inform the final Federal
Good Neighbor Plan.48 49 In its final actions on both SIP
disapprovals, and the Federal Good Neighbor Plan, the EPA provided an
explanation of the adjustments and other modifications made to
construct the 2016v3 platform. Details on the 2016v3 air quality
modeling and the methods for projecting design values and determining
contributions in 2023 and 2026 based on this platform are described in
the TSD titled ``Air Quality

[[Page 12676]]

Modeling Final Rule TSD--2015 Ozone NAAQS Good Neighbor Plan,''
hereafter known as the Final Good Neighbor Plan AQM TSD.\50\ Additional
details related to the 2016v3 emissions platform are located in the TSD
titled ``Preparation of Emissions Inventories for the 2016v3 North
American Emissions Modeling Platform,'' hereafter known as the 2016v3
Emissions Modeling TSD, included in Docket ID No. EPA-HQ-OAR-2021-
0668.\51\
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\48\ ``Air Plan Disapprovals; Interstate Transport of Air
Pollution for the 2015 8-Hour Ozone National Ambient Air Quality
Standards,'' 88 FR 9336 (February 13, 2023), and ``Federal ``Good
Neighbor Plan'' for the 2015 Ozone National Ambient Air Quality
Standards,'' 88 FR 36654 (June 5, 2023).
\49\ In the Federal Good Neighbor Plan, the EPA identified and
finalized FIPs for 23 states. This included the 21 states included
in the SIP Disapproval action, as well as Pennsylvania and Virginia.
The EPA had an obligation to finalize a FIP for these two states
(and Utah) following the EPA's finding of a failure to submit a SIP
from these two states (84 FR 66612). The EPA has not since received
SIP submissions from Pennsylvania or Virginia.
\50\ Air Quality Modeling Final Rule Technical Support
Document--2015 Ozone NAAQS Good Neighbor Plan in Docket ID No. EPA-
HQ-OAR-2021-0668.
\51\ 2016v3 Emissions Modeling TSD in Docket ID No. EPA-HQ-OAR-
2021-0668.
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In this proposed action, the EPA primarily relies on modeling based
on the 2016v3 emissions platform coupled with measured data in Steps 1
and 2 of the 4-step interstate transport framework, which will
generally be referenced within this action as the ``2016v3 modeling''
for 2023 and 2026. As discussed further in section III.D.2. of this
document, the EPA is also applying its findings regarding violating-
monitor maintenance-only receptors in 2023 using certified monitoring
data and regulatory design values for 2021 and 2022. The EPA used the
2016v3 modeling to calculate contributions to these receptors. By again
using this same set of monitoring data and updated modeling results,
the EPA is using the most current and technically appropriate
information for this proposed rulemaking and also ensuring that its
regulatory determinations for these remaining states are wholly
consistent with the findings informing the EPA's final determinations
for all of the states included in the final Federal Good Neighbor Plan.
In this proposed action, the EPA is accepting public comment on the
2016v3 modeling and the violating-monitor methodology, solely as they
relate to Arizona, Iowa, Kansas, New Mexico, and Tennessee interstate
transport obligations for the 2015 ozone NAAQS. The EPA is not
reopening the modeling in relation to any other State or regulatory
action. Any comments received on the modeling that are not relevant to
the evaluation of these states' interstate transport obligations will
be treated as beyond the scope of this action.
States may have chosen to rely on the results of prior versions of
EPA's modeling and/or alternative modeling performed by states or MJOs
to evaluate downwind air quality problems and contributions as part of
their SIP submissions. The EPA is not proposing to disapprove any
State's submission in this action based on the State's choice of
modeling, but, consistent with its disapproval action, based on the
EPA's evaluation of the entire record, which aims to factually
determine whether states are projected to significantly contribute to
or interfere with maintenance in the 2023 analytical year. See 88 FR at
9343. In section IV.B. of this document, the EPA evaluates how Arizona,
Iowa, Kansas, New Mexico, and Tennessee used air quality modeling
information in their SIP submissions.
A summary of the methodology and results of the 2016v3 modeling for
2023 and 2026, along with the application of the EPA's Step 1 and Step
2 methodology for identifying receptors and upwind states that
contribute to those receptors can be found in the Final Good Neighbor
Plan AQM TSD. That document also contains explanations as to how
current measured ozone levels based on data for 2021 and 2022 at other
monitoring sites (i.e., monitoring sites that are not projected to be
receptors in 2023 based on air quality modeling) confirm the likely
continuation of elevated ozone levels in 2023 at these locations. This
analysis shows that each of the five states in this action are linked
at or above (i.e., contributing equal to or more than) 1 percent of the
NAAQS to one or more of these monitors. Kansas and Tennessee are linked
only to violating-monitor receptors, and not to modeling-based
receptors. In recognition that the EPA had not proposed these sites as
receptors, linkages to such receptors were used only in a
``confirmatory'' way to inform the final Disapproval action and Good
Neighbor Plan (i.e., to reinforce linkage findings as to states that
were otherwise linked to modeling-based receptors). In this proposed
action, the EPA finds the existence of such linkages is sufficient to
establish that a State contributes to such receptors and is thus an
adequate basis on which to propose disapproval of the SIP submissions
from Kansas and Tennesse.

D. The EPA's Approach To Evaluating Interstate Transport for the 2015
Ozone NAAQS

The EPA has applied a consistent set of policy judgments across all
states for purposes of evaluating interstate transport obligations and
the approvability of interstate transport SIP submissions for the 2015
ozone NAAQS under CAA section 110(a)(2)(D)(i)(I) and proposes to
continue to do so in this action. These policy judgments conform with
relevant case law and past Agency practice as reflected in the CSAPR
and related rulemakings. Employing a nationally consistent approach is
particularly important in the context of interstate ozone transport,
which is a regional-scale pollution problem characterized by the
collective contribution from many upwind states to geographically
dispersed monitors over distances of hundreds of miles. Effective
policy solutions to the problem of interstate ozone transport going
back to the NO<INF>X</INF> SIP Call have necessitated the application
of a uniform framework of policy judgments to ensure an ``efficient and
equitable'' approach. See EME Homer City Generation, LP v. EPA, 572
U.S. 489, 519 (2014).
In the March, August, and October 2018 memoranda, the EPA
recognized that states may be able to establish alternative approaches
to addressing their interstate transport obligations for the 2015 ozone
NAAQS that vary from a nationally uniform framework. The EPA emphasized
in these memoranda, however, that such alternative approaches must be
technically justified and appropriate in light of the facts and
circumstances of each particular State's SIP submission. In general,
the EPA continues to believe that deviation from a nationally
consistent approach to ozone transport must have a well-documented
technical basis that is consistent with CAA obligations and relevant
case law. Where states submitted SIP submissions that rely on any such
potential concepts as the EPA or others may have identified or
suggested in the past, the EPA will evaluate whether the State
adequately justified the technical and legal basis for doing so.
The EPA notes that certain 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
interstate transport obligations for the 2015 ozone NAAQS. Attachment A
to the March 2018 memorandum identified a ``Preliminary List of
Potential Flexibilities'' that could potentially inform SIP
development. However, the EPA made clear in both the March 2018
memorandum \52\ and in Attachment A that the list of ideas was not
endorsed by the Agency but rather ``comments provided in various
forums'' on which the EPA sought ``feedback from interested
stakeholders.'' \53\ 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

[[Page 12677]]

use these approaches.'' \54\ 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 one or more of these ideas in support of
their SIP submissions, the EPA will thoroughly review the technical and
legal justifications for doing so.
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\52\ March 2018 memorandum, Attachment A.
\53\ Id. at A-1.
\54\ Id.
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The remainder of this section describes the EPA's analytic
framework and interpretation of the critical terms of the good neighbor
provision with respect to analytic year, definition of nonattainment
and maintenance receptors, selection of contribution threshold, and
multifactor control strategy assessment.
1. Selection of Analytic Years
In this section, the EPA describes its process for selecting
analytic years for air quality modeling and analyses performed to
identify nonattainment and maintenance receptors and identify upwind
State linkages. The EPA is retaining the 2023 and 2026 analytical years
used to inform the obligations of the 23 states included in the Federal
Good Neighbor Plan, to ensure consistency and equitable treatment of
all states. In the Federal Good Neighbor Plan, the EPA evaluated air
quality to identify receptors at Step 1 and evaluate interstate
contributions at Step 2 for two analytic years: 2023 and 2026.\55\
These years are the last full ozone seasons before the Moderate and
Serious area attainment dates for the 2015 ozone NAAQS (ozone seasons
for purposes of the Federal Good Neighbor Plan run each year from May
1-September 30, see 40 CFR 52.38(b)(1) and 40 CFR 52.40(c)(1)). To
demonstrate attainment by these deadlines, downwind states would be
required to rely on design values calculated using ozone data from 2021
through 2023 and 2024 through 2026, respectively. Areas that do not
attain by the deadline may be ``bumped up'' to a higher nonattainment
classification level per CAA sections 181 and 182, thereby incurring
additional ongoing obligations. Thus, in the Federal Good Neighbor
Plan, consistent with each of its prior good neighbor rulemakings, the
EPA focused its analysis on the last full ozone seasons before the
attainment dates (i.e., 2023 and 2026).
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\55\ While the 2023 analytic year provides a sufficient basis to
act on the SIP submissions in this action, consistent with the EPA's
Disapproval action, see 88 FR 9340-41, the EPA uses the 2026
analytic year to ensure a complete Step 3 analysis in the context of
developing the FIP, see 88 FR 36694.
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The Agency recognizes that in applying its 2023 and 2026 analytics
to inform this action, it may be perceived as acting inconsistently
with a longstanding policy of always considering a future analytic year
from the standpoint of the timing of its rulemaking action. However,
the EPA determined that several important, overriding considerations
warrant adopting this approach in this supplemental rulemaking. As
explained in section I.A. of this document, it is imperative to
maintain a consistent set of analytical and policy determinations
across all states in the context of addressing the interstate ozone
problem; the EPA is doing so by using a consistent set of data and
analytical conclusions between the states included in this action and
those for which the EPA has already rendered final determinations in
the final SIP Disapproval action and the Federal Good Neighbor Plan.
Were the EPA to conduct a new set of air quality analyses tied to years
beyond 2023 or 2026, the EPA would separately evaluate these states
using different data than that which informed and defined the
obligations of all other states, solely as a result of the timing of
the EPA's action on these states. Where the need for parity among
states or other jurisdictions in like circumstances warrants it, courts
have recognized that it may be appropriate for agencies like the EPA to
rely on a unified dataset to ensure consistency in treatment. See Bd.
County Commissioners of Weld County v. EPA, 72 F.4th 284, 290 (D.C.
Cir. 2023) (upholding as reasonable the EPA's determination that
``greater parity among counties and faster turnaround [ ] make the
original data a better choice than partial updating''). The importance
of use of a single, already-developed dataset focused on the years 2023
and 2026 to define good neighbor obligations for all states to ensure
consistency among states and for ``faster turnaround'' to complete this
supplemental rulemaking is, in the EPA's judgment, sufficiently
compelling to justify this approach here.
The EPA's use of a common and unified dataset here is consistent
with all of its past good neighbor rulemakings, including those in
which the EPA conducted updated air quality analysis to address
remaining good neighbor obligations. In both the CSAPR Update and the
Revised CSAPR Update, the EPA took action to address good neighbor FIP
actions that had been remanded to the EPA. In each case, the EPA
addressed the remanded obligations for all of the covered states
through analysis of a new analytic year. This ensured consistency among
all of the states where there were good neighbor obligations that
needed to be addressed. See, e.g., 86 FR 23067-68 (discussing error
correction for Kentucky ``consistent with EPA's methodology to address
the other 20 states'' included in that action). Further, the EPA
already had updated modeling at hand that could inform its new action.
See, e.g., id. at 23074, 23079-80. Likewise, where all of a group of
states' obligations were being addressed on remand from an action that
had not been vacated (as was the case in both the CSAPR Update and the
Revised CSAPR Update), it was important to reflect the emissions
reductions and air quality improvements that were already being
achieved from the non-vacated action in the baseline. See, e.g., id. at
23075. In this case, the EPA is not re-evaluating a group of states but
addressing additional states in a manner that ensures consistent
treatment with the first set of states. This circumstance is analogous
to the supplemental rulemaking the EPA undertook soon following the
original CSAPR rulemaking to add several states to those programs based
on the same data and analysis that informed the CSAPR. See 76 FR 80760
(December 27, 2011). In the EPA's judgment, the relevant considerations
therefore weigh in favor of using the currently available air quality
data that has already been used to define other states' obligations.
In addition, like the CSAPR supplemental rulemaking, the timing of
this action is the result of procedural happenstance, rather than a
substantive difference in the circumstances of any of these five
states. This timing was driven by the nature of the EPA's prior
proposed or final actions, or lack of such actions, that had been taken
at the time the EPA completed its final, updated air quality analysis
informing its final determinations on other states' obligations in the
Federal Good Neighbor Plan (explained further in section III.C. of this
document). This final analysis of obligations based on 2023 and 2026
analytics necessitated the EPA's reevaluation of its proposals on
Arizona and Tennessee's SIP submissions, as well as the EPA's past
final actions on Iowa and Kansas' SIPs.\56\ In these circumstances,
given the potential change in the status of these states, the EPA also
found it would be appropriate to provide an opportunity

[[Page 12678]]

for public comment on the EPA's changed basis for action.
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\56\ The EPA has not taken any previous proposed or final action
on New Mexico's SIP submission.
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Further, shifting the analysis of good neighbor obligations forward
to a new analytic year for these five states would not be relevant to a
proper definition of these good neighbor obligations, and switching the
analytic year(s) for just these five states could create an inequitable
result both amongst other upwind states and between these five states
and the downwind states to which they are linked. Creating a different
set of data for a later year for these states, when the Federal Good
Neighbor Plan has already defined requirements and is in effect for
certain other states, would introduce an interdependency, or ``who goes
first,'' problem that the EPA's framework generally is designed to
avoid. See Ky. Energy & Env't Cabinet v. EPA, No. 23-3605 (6th Cir.
Nov. 9, 2023), Slip Op. at 8. The EPA is not reopening the
determinations made for the 23 upwind states covered in the Federal
Good Neighbor Plan, and 2023 and 2026 were appropriately selected as
the analytical years to inform the EPA's evaluation of these states.
See 88 FR at 36694-96. These years are associated with the statutory
attainment schedule faced by the downwind states with designated
nonattainment areas where the identified receptors are located. It is
at the least reasonable, therefore, to align these five states'
evaluation with the remainder of the states in the country, which will
maintain parity among all jurisdictions, which is preferable to only
``partially updating'' the analysis in the case of a handful of states.
Weld County, 72 F.4th at 290. This is a particularly important
consideration in implementing the good neighbor provision for ozone.
The EPA must ensure each state is held to the elimination of its own
significant contribution. See North Carolina v. EPA, 531 F.3d 896, 920-
21 (D.C. Cir. 2008). And interstate ozone pollution presents a
``collective contribution'' problem in which the EPA must allocate a
fair share of responsibility among sources across multiple states. See
Maryland v. EPA, 1185 F.3d at 120304 (D.C. Cir. 2020); id. at 1204
(``So long as upwind sources significantly contribute to [a state's]
nonattainment at its 2021 [Marginal] attainment deadline, they violate
the Good Neighbor Provision.'').
As the Maryland court recognized, the consequences on downwind
nonattainment areas from failure to obtain relief from upwind
significant contribution are not just continuing poor air quality, but
also regulatory requirements that apply for years into the future,
including ``a requirement to provide for annual emissions reductions in
SIPs.'' Id. (citing CAA section 182(b)). The relief that can be
afforded through addressing the upwind states' significant
contribution, as proposed in this action, will therefore potentially
lessen regulatory burdens on downwind states that Congress commanded
they are not to bear alone. See 88 FR 36840 (discussing the history of
downwind states' and the EPA's reliance on emissions reductions
achieved through prior good neighbor rules in, for example,
redesignation actions and maintenance plans); cf. Maryland, 958 F.3d at
1200 (a state that cannot obtain relief from an upwind state's
significant contribution to a continuing nonattainment designation ``is
stuck in regulatory limbo''). Thus, using a common dataset makes good
sense in this context; it is consistent with the requirements and the
purpose of the good neighbor provision, and it ensures these
obligations are implemented both expeditiously and in a consistent and
equitable manner. Weld County, 72 F.4th at 290.\57\
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\57\ While use of a common dataset makes sense for the reasons
stated, the EPA notes that it is not aware of other data sets,
including either monitoring data or modeling projections, that would
suggest alternative regulatory conclusions from those proposed here.
As evidenced by the most recent certified monitoring data and design
values from 2021 and 2022 used in the violating-monitor receptor-
identification methodology, relatively elevated ozone levels
exceeding the NAAQS continue to be observed throughout much of the
continental U.S., including in the designated nonattainment areas
where many of the ozone-transport receptors identified in the
Federal Good Neighbor Plan are located.
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The use of a common set of air quality data was upheld in Weld
County. The court, however, went on to find that another portion of the
EPA's action under review constituted impermissible retroactive
rulemaking, because it ``effectively backdated'' a nonattainment
designation, leaving a state that would have had a three-year period to
reach attainment in the position of ``missing a compliance deadline
that passed before the underlying legal obligation was imposed.'' 72
F.4th at 293. This proposed action does not operate retroactively. The
EPA's use of the 2023 analytic year does not in and of itself impose
any obligations on any sources or states. Rather it provides a common
dataset to assess whether any state is contributing to downwind
problems attaining the NAAQS. The EPA proposes to set compliance
obligations based on the amount of time needed for sources to come into
compliance and does not propose to impose liability on such sources for
not meeting the proposed obligations at some point in the past. See
section VII.A.4. and B. of this document. Nor would the proposed rule
apply retroactively to the five states with SIP submissions proposed to
be disapproved. The EPA is not proposing to backdate the date of
finalization of these proposed disapprovals to sometime in the past.
Rather, if the proposed disapprovals are finalized, the only legal
consequence--the establishment of a duty on the EPA to promulgate a
FIP--would run from the date a final action is taken. Unlike the three-
year ``runway'' allowed to reach attainment that the court found had
been impermissibly denied to the state in Weld County, 72 F.4th at 293,
the statute affords no such period following a SIP disapproval. CAA
section 110(c)(1). The EPA need not wait a single day to promulgate a
FIP upon issuing a disapproval of a SIP submission. EME Homer City, 489
U.S. at 509. Nor is the EPA obligated to give states a second chance to
submit a SIP before issuing a FIP. Id. Nonetheless, the states covered
in this supplemental proposed rulemaking have been on notice since the
issuance of the 2016v3 modeling and violating-monitor methodology in
connection with the SIP Disapproval and Federal Good Neighbor Plan
actions in winter of 2023 that they may be subject to a good neighbor
FIP due to identified linkages with downwind receptors. 88 FR 36656.
None of these five states has moved since that time to submit a revised
SIP submission to address the relevant requirements.
For consistency, the Agency similarly conducted its overcontrol
analysis for this action using the 2023 and 2026 data (see section
VI.D. of this document). The EPA recognizes that it is appropriate to
provide sufficient lead time to allow sources in these five states to
comply with the proposed requirements. Based on the compliance-timing
analysis conducted in the final Federal Good Neighbor Plan and applied
here (as discussed in section VII. of this document), the dates
proposed for the onset of these requirements for these five states fall
after the 2023 and 2026 analytic years. This too is a matter of
happenstance and does not justify a deviation from the definition of
these states' good neighbor obligations. Similarly, assuming favorable
outcomes in the ongoing litigation resulting in stays of the Federal
Good Neighbor Plan for several states pending judicial review, the EPA
anticipates adjusting the timing of compliance obligations if these
states are eventually made subject to the Federal Good Neighbor Plan.
These circumstances are analogous to an issue the EPA addressed in the
final

[[Page 12679]]

Federal Good Neighbor Plan regarding the ability of individual sources
to apply for and obtain compliance extensions. The EPA explained that
where sources obtained such extensions, the EPA did not intend to
conduct further analysis of whether those reductions were still
required based on updated air quality analysis. As the EPA explained,
the Agency did not think individual sources should gain the benefit of
delaying emissions reductions simply in the hopes that they could show
those reductions would be overcontrol. This would introduce an inter-
dependency into the analysis, whereas each source must be held to the
elimination of its portion of significant contribution. Necessity, the
EPA explained, may demand some additional amount of time for
compliance, but equity demands that individual sources not gain an
untoward advantage from delay and reliance on other sources' timelier
compliance. See 88 FR at 36750 n.253. Thus, here, the EPA continues to
conduct its overcontrol analysis using the common datasets for 2023 and
2026, to ensure consistent and equitable determinations for what
constitutes ``significant contribution'' even if the implementation of
those emissions reductions may be delayed in certain states or for
certain sources.
Thus, the EPA proposes to continue to use its 2023 and 2026
analytics, to ensure parity by holding all states to a consistent set
of data in defining good neighbor obligations for the 2015 ozone NAAQS,
to avoid improperly shifting the burden of emissions reductions to
other upwind and downwind states, and to provide for an efficient and
administratively workable resolution of these remaining obligations for
five additional states.
2. Step 1 of the 4-Step Interstate Transport Framework
In Step 1, the EPA identifies monitoring sites that are projected
to have problems attaining and/or maintaining the NAAQS in the 2023
analytic year. This approach reflects the EPA's interpretation of the
terms ``nonattainment'' and ``maintenance'' as used in the good
neighbor provision in the context of the ozone NAAQS. See 88 FR at
9341-42. Where the EPA's analysis shows that a site does not meet the
definition of a nonattainment or maintenance receptor, the EPA excludes
that site from further analysis under the EPA's 4-step interstate
transport framework. At Step 2 of the 4-step interstate transport
framework, the EPA considers those sites identified as a nonattainment
or maintenance receptor in 2023 and identifies which upwind states
contribute to those receptors above the contribution threshold.
The EPA's approach to identifying ozone nonattainment and
maintenance receptors in this action is the same as that used in the
Federal Good Neighbor Plan.\58\ This 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.\59\ To summarize this methodology:
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\58\ See Air Quality Modeling Final Rule Technical Support
Document--2015 Ozone NAAQS Good Neighbor Plan in Docket ID No. EPA-
HQ-OAR-2021-0668 for additional details on the EPA's evaluation
nonattainment and maintenance receptor identification.
\59\ See North Carolina v. EPA, 531 F.3d at 910-11 (holding that
the EPA must give ``independent significance'' to each prong of CAA
section 110(a)(2)(D)(i)(I)).
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The EPA identifies nonattainment receptors as those monitoring
sites that are projected to have average design values that exceed the
NAAQS and that are also measuring nonattainment based on the most
recent monitored design values. This approach is consistent with prior
transport rulemakings, such as the CSAPR Update, where the EPA defined
nonattainment receptors as those monitoring sites that both measure
nonattainment based on recent monitoring data (here, using certified
2021 data to be consistent with the analysis in the Good Neighbor Plan)
and that the EPA modeling projected to be in nonattainment in the
analytic year (i.e., 2023).60 61
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\60\ The 2021 design values were the most current official
design values available for use in the 2016v3 modeling. The 2021
ozone design values, by monitoring site, can be found in the file
``Final GNP O3 DVs Contributions'', in Docket ID No. EPA-HQ-OAR-
2021-0668.
\61\ See 81 FR 74504 (October 26, 2016). This same concept,
relying on both current monitoring data and modeling to define
nonattainment receptor, was also applied in CAIR. See 70 FR at
25241, 25249 (January 14, 2005); see also North Carolina, 531 F.3d
at 913-14 (affirming as reasonable the EPA's approach to defining
nonattainment in CAIR).
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In addition, the EPA identified a receptor to be a ``maintenance''
receptor for purposes of defining interference with maintenance,
consistent with the method used in the CSAPR and upheld by the D.C.
Circuit in EME Homer City Generation, L.P. v. EPA, 795 F.3d 118, 136
(D.C. Cir. 2015) (EME Homer City II).\62\ Specifically, the EPA
identified maintenance receptors as those receptors that would have
difficulty maintaining the relevant NAAQS in a scenario that takes into
account historical variability in air quality at that receptor. The
variability in air quality was determined by evaluating the ``maximum''
future design value at each receptor based on a projection of the
maximum measured design value over the relevant period. The EPA
interprets the projected maximum future design value to be a potential
future air quality outcome consistent with the meteorology that yielded
maximum measured concentrations in the ambient data set analyzed for
that receptor (i.e., ozone conducive meteorology). The EPA also
recognizes that previously experienced meteorological conditions (e.g.,
dominant wind direction, temperatures, and air mass patterns) promoting
ozone formation that led to maximum concentrations in the measured data
may reoccur in the future. The maximum design value gives a reasonable
projection of future air quality at the receptor under a scenario in
which such conditions do, in fact, reoccur. The projected maximum
design value is used to identify upwind emissions that, under those
circumstances, could interfere with the downwind area's ability to
maintain the NAAQS.
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\62\ See 76 FR 48208 (August 8, 2011). CSAPR Update and Revised
CSAPR Update also used this approach. See 81 FR 74504 (October 26,
2016) and 86 FR 23054 (April 30, 2021).
---------------------------------------------------------------------------

Nonattainment receptors are also, by definition, maintenance
receptors, and so the EPA often uses the term ``maintenance-only'' to
refer to those receptors that are not nonattainment receptors.
Consistent with the concepts for maintenance receptors, as described
earlier, the EPA identifies ``maintenance-only'' receptors as those
monitoring sites that have projected average design values above the
level of the applicable NAAQS, but that are not currently measuring
nonattainment based on the most recent official design values.\63\ 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.
---------------------------------------------------------------------------

\63\ The Agency often uses the terms maintenance receptor and
maintenance-only receptor interchangeably when discussing
maintenance receptors that are not also nonattainment receptors.
---------------------------------------------------------------------------

The Agency has looked closely at measured ozone levels at ambient
monitoring sites in 2021 and 2022 for the purposes of informing the
identification of potential additional receptors in 2023. As explained
in more detail in the February 13, 2022, final

[[Page 12680]]

action disapproving 19 states' good neighbor SIP submissions, and
partially approving and partially disapproving 2 states' good neighbor
SIP submissions (``Disapproval action''), see 88 FR at 9349-50, the EPA
finds there is a basis to consider certain sites with elevated ozone
levels that are not otherwise identified as receptors to be an
additional type of maintenance-only receptor given the likelihood that
ozone levels above the NAAQS could persist at those locations through
at least 2023. These are referred to as violating-monitor maintenance-
only receptors (violating-monitor receptors). In this action, the EPA
proposes to use certified ambient monitoring data as an additional
method to identify maintenance-only receptors. More specifically,
violating-monitor receptors are monitoring sites with measured 2021 and
2022 design values and 2021 and 2022 4th high maximum daily average 8-
hour ozone concentrations that exceed the NAAQS, despite having model-
projected average and maximum design values for 2023 below the
NAAQS.\64\ The EPA finds these sites are at continuing risk of failing
to maintain the 2015 ozone NAAQS, which justifies categorizing these
sites as maintenance-only receptors. By applying the criteria that
certified 2021 and 2022 design values and 2021 and 2022 4th high
maximum daily average 8-hour ozone concentrations must all exceed the
NAAQS the EPA gives due consideration to both measured air quality data
and its modeling projections. This reasonably identifies monitoring
sites as receptors in 2023 using this methodology. If sites do not meet
these criteria, then the EPA could reasonably anticipate these sites to
not have a problem maintaining the NAAQS in 2023 and should therefore
not be considered receptors.\65\
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\64\ A design value is calculated using the annual fourth-
highest maximum daily 8-hour ozone concentration averaged over 3
years.
\65\ We also note that 2023 monitoring data is not yet
certified, and further, because the Federal Good Neighbor Plan was
in effect in several states during the 2023 ozone season (and
sources may have otherwise voluntarily taken emissions-reduction
measures consistent with the Federal Good Neighbor Plan either
earlier than the effective date or in states where the Federal Good
Neighbor Plan was stayed), the 2023 monitoring data is less reliable
for use in establishing an air quality baseline, i.e., one in the
absence of the Federal Good Neighbor Plan.
---------------------------------------------------------------------------

The EPA is not reopening its Step 1 methodologies or determinations
in this action as to the 23 states included in the Federal Good
Neighbor Plan. The EPA proposes to apply this same methodology to
Arizona, Iowa, Kansas, New Mexico, and Tennessee. Comments that are
unrelated to or go beyond the application of these methodologies to
these five states will be treated as beyond the scope of this action.
3. Step 2 of the 4-Step Interstate Transport Framework
In Step 2 the contribution of each upwind State to each receptor in
the 2023 analytic year is quantified. This approach reflects how the
Agency gives meaning to the term ``contribute'' in the good neighbor
provision in relation to the ``collective contribution'' problem posed
by interstate ozone pollution. See 88 FR at 9342. 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 ozone NAAQS), the upwind State is not
``linked'' to a downwind air quality problem, and the EPA, therefore,
concludes that the State does not contribute significantly to
nonattainment or interfere with maintenance of the NAAQS in the
downwind states. However, if a State's average contribution equals or
exceeds the 1 percent threshold, the EPA further evaluates the State's
emissions 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 pursuant to the
requirements of CAA section 110(a)(2)(D)(i)(I).
In this proposed action, the EPA relies 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 ozone NAAQS
(i.e., 0.70 ppb) at downwind receptors. This is consistent with the
Step 2 approach that the EPA applied in the Disapproval action and in
the Federal Good Neighbor Plan. The EPA has acknowledged that states
may have been able to justify use of a different threshold at Step 2.
For reasons explained in section IV. of this document, no State
included in this action successfully made this demonstration. In
addition, the EPA explained in both the Disapproval action and in the
Federal Good Neighbor Plan that the need for consistent treatment of
all states counsels against recognizing alternative thresholds on a
state-by-state basis. Based on its experience since the release of the
August 2018 memorandum, the EPA has also determined, as explained in
the Disapproval action and Federal Good Neighbor Plan, that it is not a
good use of Agency resources nor is it wise policy for the EPA to
attempt to justify the use of an alternative threshold on behalf of any
State that failed to conduct an adequate analysis itself. Likewise,
maintaining continuity across ozone NAAQS through consistent
application of a 1 percent of NAAQS threshold at Step 2 is appropriate,
so that, as the NAAQS is revised and made more protective, the
contribution threshold is correspondingly adjusted as well. See 88 FR
at 36712-17; 88 FR at 9371-75. See also 86 FR at 23085 (use of 1
percent threshold in the Revised CSAPR Update); 81 FR at 74518 (basis
for use of 1 percent threshold for the 2008 ozone NAAQS in the CSAPR
Update); 76 FR at 48237-38 (original determination to use 1 percent
threshold for the 1997 ozone NAAQS in CSAPR).
Therefore, application of a consistent contribution threshold is
important to identify those upwind states that should have
responsibility for addressing their contribution to the downwind
nonattainment and maintenance problems to which they collectively
contribute. Continuing to use 1 percent of the NAAQS as the screening
metric to evaluate collective contribution from many upwind states also
allows the EPA (and states) to apply a consistent framework to evaluate
interstate emissions transport under the interstate transport provision
from one NAAQS to the next and helps ensure that good neighbor
obligations align with the stringency of the NAAQS.
The issue of the appropriate contribution threshold to apply was
thoroughly addressed in the Disapproval action and the Federal Good
Neighbor Plan rulemakings, and the EPA responded to numerous comments
on this topic. The EPA is not reopening this issue in this action,
except as to the question of whether there is any reason to regard the
Step 2 contribution threshold differently for any of these five
additional states. The Agency, however, sees no basis to do so.
4. Step 3 of the 4-Step Interstate Transport Framework
At Step 3 of the 4-step interstate transport framework, the EPA
further evaluates a State's emissions, 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). This approach reflects the EPA's interpretation of
the phrases ``contribute significantly'' or ``interfere

[[Page 12681]]

with maintenance'' as used in the good neighbor provision in the
context of the ozone NAAQS. See 88 FR at 9342-43.
Under the EPA's longstanding approach to eliminating significant
contribution to nonattainment and interference with maintenance, at
Step 3, a multi-factor assessment of potential emissions controls would
be conducted for states linked at Step 1 and 2. The EPA's analysis at
Step 3 in prior Federal actions addressing interstate transport
requirements has primarily focused on an evaluation of cost-
effectiveness of potential emissions controls (on a marginal cost-per-
ton basis), the total emissions reductions that may be achieved by
requiring such controls (if applied across all linked upwind states),
and an evaluation of the air quality impacts such emissions reductions
would have on the downwind receptors to which a State is linked; other
factors may potentially be relevant if adequately supported.
The EPA has consistently applied this general approach to Step 3
when identifying emissions contributions that the Agency has determined
to be ``significant'' (or interfere with maintenance) in each of its
prior Federal and regional ozone transport rulemakings, and this
interpretation of the statute has been upheld by the Supreme Court. See
EME Homer City, 572 U.S. 489, 519 (2014). While the EPA has not
directed states that they must conduct a Step 3 analysis in precisely
the manner the EPA has done in its prior regional transport
rulemakings, State implementation plans addressing the obligations in
CAA section 110(a)(2)(D)(i)(I) must prohibit ``any source or other type
of emissions activity within the State'' from emitting air pollutants
which will contribute significantly to downwind air quality problems.
Thus, states must undertake an analysis similar to the EPA's analysis
(or an alternative approach to defining ``significance'' that comports
with the statute's objectives) to determine whether and to what degree
emissions from a State should be ``prohibited'' to eliminate emissions
that will ``contribute significantly to nonattainment in or interfere
with maintenance of'' the NAAQS in any other state. See 88 FR at 9342-
43, 9375-76.
In general, where the EPA's or state-provided 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
SIP submission approval. In general, the emissions-reducing effects of
all existing emissions control requirements are already reflected in
the future year projected 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) despite these existing controls, but that State believes it
has no outstanding good neighbor obligations, the EPA expects the State
to provide sufficient justification to support a conclusion that the
State has adequate provisions prohibiting ``any source or other type of
emissions activity within the State from emitting any air pollutant in
amounts which will'' ``contribute significantly to nonattainment in, or
interfere with maintenance by,'' any other State with respect to the
NAAQS. See CAA section 110(a)(2)(D)(i)(I). While the EPA has not
prescribed a particular method for this assessment, the EPA expects
states at a minimum to present a sufficient technical evaluation. This
would typically include information on emissions sources, applicable
control technologies, emissions reductions, costs, cost-effectiveness,
and downwind air quality impacts of the estimated reductions, before
concluding that no additional emissions controls should be
required.\66\
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\66\ As examples of general approaches for how such an analysis
could be conducted for their sources, states could look to the CSAPR
Update, 81 FR 74504, 74539-51; CSAPR, 76 FR 48208, 48246-63; CAIR,
70 FR 25162, 25195-229; or the NO<INF>X</INF> SIP Call, 63 FR 57356,
57399-405. See also Revised CSAPR Update, 86 FR 23054, 23086-23116.
Consistently across these rulemakings, the EPA has developed
emissions inventories, analyzed different levels of control
stringency at different cost thresholds, and assessed resulting
downwind air quality improvements.
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As explained in section III.A. in this document, the EPA and states
must give independent significance to Prong 1 (significant contribution
to nonattainment) and Prong 2 (interference with maintenance) when
evaluating downwind air quality problems under CAA section
110(a)(2)(D)(i)(I).\67\ The EPA gives effect to Prong 2 through
identifying receptors that may have trouble attaining the NAAQS under
varying air quality and meteorological conditions. EME Homer City
upheld the EPA's approach to using cost to determine ``amounts'' with
respect to both Prong 1 and 2. EPA v. EME Homer City Generation, 572
U.S. at 518-520. The EPA's use of the term ``significant contribution''
in its analysis at the third step of the 4-step interstate transport
framework is applied for both Prongs 1 and 2. This approach to giving
effect to the ``interfere with maintenance'' prong has been upheld
twice by the D.C. Circuit. See EME Homer City, 795 F.3d at 136;
Wisconsin, 938 F.3d at 325-27. In effect, the EPA's determination of
what level of upwind contribution constitutes ``interference'' with a
maintenance receptor is the same determination as what constitutes
``significant contribution'' for a nonattainment receptor. Nonetheless,
this continues to give independent effect to Prong 2 because the EPA
applies a broader definition for identifying maintenance receptors,
which accounts for the possibility of problems maintaining the NAAQS
under realistic potential future conditions. While the EPA and others
may occasionally use the language of ``significance'' as a shorthand
for determinations at the third step under both Prongs 1 and 2, this
does not detract from the fact that the EPA gives Prong 2 independent
effect under the 4-step interstate transport framework. Alternative
approaches to defining and prohibiting emissions that ``interfere with
maintenance'' must be, like the EPA's approach, legally and technically
justified and give effect to the language of the statute in a manner
that ensures states' good neighbor obligations are defined in a
consistent and equitable manner.
---------------------------------------------------------------------------

\67\ See North Carolina v. EPA, 531 F.3d 896, 909-11 (D.C. Cir.
2008).
---------------------------------------------------------------------------

As explained in section IV.B. and V.A. of this document, no states
whose SIP submissions the EPA is proposing to partially disapprove in
this action conducted an adequate analysis at Step 3, following either
the EPA's approach or an alternative approach. As explained in section
I.A. of this document and further detailed in section VI. of this
document, the EPA is proposing to apply the same Step 3 analysis and
methodology completed in the Federal Good Neighbor Plan for 23 states
to the additional states of Arizona, Iowa, Kansas, New Mexico, and
Tennessee. The EPA's approach to Step 3 is explained in section
III.B.1.c. of the Federal Good Neighbor Plan.\68\
---------------------------------------------------------------------------

\68\ 88 FR 36654, at 36678.
---------------------------------------------------------------------------

5. Step 4 of the 4-Step Interstate Transport Framework
At Step 4, states (or the EPA) develop permanent and federally-
enforceable control strategies to achieve the emissions reductions
determined to be necessary at Step 3 to eliminate significant
contribution to nonattainment or interference with maintenance of the
NAAQS, as necessary to comply with the terms of the good neighbor
provision requiring that SIPs (or FIPs) ``contain adequate provisions
prohibiting'' such emissions. 88 FR at 9343. These control strategies

[[Page 12682]]

must be included in the State's SIP so that they are made permanent and
federally enforceable. See CAA section 110(a)(2)(D) (``Each such [SIP]
shall . . . contain adequate provisions--prohibiting . . .''). 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 submission).
As with the previous steps of the framework, as explained in
section I.A. of this document and further detailed in section VII. of
this document, in proposing FIPs for Arizona, Iowa, Kansas, New Mexico,
and Tennessee, the EPA is proposing to implement necessary emissions
reductions through the same set of permanent and enforceable measures
promulgated for 23 other states in the Federal Good Neighbor Plan. The
EPA's approach to Step 4 is explained in section III.B.1.d. of the
Federal Good Neighbor Plan.\69\
---------------------------------------------------------------------------

\69\ 88 FR 36654, at 36684.
---------------------------------------------------------------------------

IV. SIP Submissions Addressing Interstate Transport of Air Pollution
for the 2015 8-Hour Ozone NAAQS

A. SIP Summaries

1. Arizona
On September 24, 2018, the Arizona Department of Environmental
Quality (ADEQ) submitted to the EPA the ``Arizona State Implementation
Plan Revision under Clean Air Act Sections 110(a)(1) and 110(a)(2) for
the 2015 Ozone National Ambient Air Quality Standards'' (``Arizona's
2018 SIP Submission''). Arizona's 2018 SIP Submission addresses the
``infrastructure'' requirements of CAA section 110(a)(2), including the
good neighbor provisions under CAA section 110(a)(2)(D)(i)(I), for the
2015 ozone NAAQS.\70\
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\70\ Letter dated September 24, 2018, from Timothy S. Franquist,
Director, Air Quality Division, ADEQ, to Michael Stoker, Regional
Administrator, EPA Region IX, Subject: ``Submittal of the Arizona
State Implementation Plan Revision under Clean Air Act sections
110(a)(1) and 110(a)(2) for the 2015 Ozone NAAQS.''
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Arizona's 2018 SIP Submission describes the 4-step interstate
transport framework established by the EPA to address the good neighbor
provision.\71\ Arizona references the results of the ozone modeling
completed by the EPA using CAMx version 6.40 and 2011 base year, made
available in the March 2018 memorandum, to identify downwind
nonattainment and maintenance receptors that may be impacted by
emissions from sources in the State at Steps 1 and 2 of the 4-step
interstate transport framework. Arizona noted that the modeling results
cited in the March 2018 memorandum demonstrate that Arizona is not
shown to contribute greater than 1 percent of the NAAQS (i.e., 0.70
ppb) to any of the modeled nonattainment or maintenance receptors in
other states.\72\ Despite asserting that ``Arizona still maintains that
the one percent threshold is poorly suited for determining contribution
obligations in the Southwestern US,'' Arizona relies on the
contribution threshold of 1 percent of the NAAQS at Step 2.\73\ Based
on the model results cited in Arizona's 2018 iSIP Submission, Arizona
finds that it does not contribute significantly to nonattainment or
maintenance receptors in other states and that it is not necessary to
identify emissions reductions or adopt any permanent or enforceable
controls under the interstate transport provision for the 2015 ozone
NAAQS.\74\ Arizona also asserts that the Arizona SIP contains adequate
provisions to ensure that air emissions in Arizona will not
significantly contribute to nonattainment or interfere with maintenance
of the 2015 ozone NAAQS in any other State in the future.\75\
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\71\ Arizona's 2018 SIP submission, 12.
\72\ Id. at 13.
\73\ Id.
\74\ Id.
\75\ Id. at 14.
---------------------------------------------------------------------------

Prior Notices Related to Arizona's SIP Submission
On June 24, 2022, the EPA proposed to approve Arizona's 2018 iSIP
Submission as meeting the good neighbor provision for the 2015 ozone
NAAQS.\76\ Our proposed approval was based upon the conclusion that
Arizona was not linked to any downwind nonattainment or maintenance
receptors, which was supported by the 2016v2 modeling described in the
notice of proposed rulemaking for the proposed approval.\77\ In
response to that proposed rulemaking, the EPA received one comment
letter providing evidence to suggest that Arizona likely contributes
significantly to interstate ozone pollution. The commenter alleged that
the 2016v2 modeling arbitrarily omits Arizona contributions to monitors
in El Paso County, Texas, and Do[ntilde]a Ana County, New Mexico, and
that Arizona is likely to significantly contribute to ozone
concentrations at these receptors. The commenter also incorporated by
reference comments that the commenter submitted in response to the
EPA's April 6, 2022, proposed FIP addressing regional ozone transport
for the 2015 ozone NAAQS, identifying additional alleged flaws and
omissions in the 2016v2 modeling.\78\
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\76\ 87 FR 37776 (June 24, 2022).
\77\ 87 FR 37776, 37782.
\78\ 87 FR 20036 (April 6, 2022).
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As described in section III.B. of this document, the EPA
constructed its 2016v3 emissions platform to update ozone transport
modeling in response to these and similar comments received on the
2016v2 modeling and to develop the 2016v3 air quality modeling. The EPA
also recognized that monitoring data for 2021 and 2022 supported
recognizing additional, violating-monitor receptors. The EPA used this
updated air quality analysis to inform its final Disapproval and
Federal Good Neighbor Plan actions.79 80 As described later
in section IV.B.1. of this document, the 2016v3 modeling and violating-
monitor receptor methodology identifies Arizona's maximum contribution
to numerous downwind maintenance receptors to be greater than 1 percent
of the standard (i.e., greater than 0.70 ppb). Because the latest
available modeling indicates that Arizona is linked to downwind
maintenance receptors, the EPA is now withdrawing its 2022 proposed
approval of Arizona's 2018 SIP Submission with respect to CAA section
110(a)(2)(d)(i)(I).
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\79\ ``Air Plan Disapprovals; Interstate Transport of Air
Pollution for the 2015 8-Hour Ozone National Ambient Air Quality
Standards,'' 88 FR 9336 (February 13, 2023), and ``Federal ``Good
Neighbor Plan'' for the 2015 Ozone National Ambient Air Quality
Standards,'' 88 FR 36654 (June 5, 2023).
\80\ Details on the 2016v3 air quality modeling and the methods
for projecting design values and determining contributions in 2023
and 2026 are described in the TSD titled ``Air Quality Modeling
Final Rule TSD--2015 Ozone NAAQS Good Neighbor Plan,'' hereafter
known as the Final Good Neighbor Plan AQM TSD.
---------------------------------------------------------------------------

2. New Mexico
The EPA made a finding in 2019 that New Mexico had failed to submit
a complete good neighbor SIP submission. See 84 FR 66612 (December 4,
2019). This triggered the EPA's obligation to promulgate a FIP for New
Mexico within 2 years. When the EPA failed to do so, multiple parties
brought deadline-suit litigation against the Agency. This resulted in a
consent decree deadline of June 1, 2024, to either promulgate a FIP for
New Mexico or approve a SIP submission fully resolving New Mexico's
good neighbor obligations. WildEarth Guardians v. Regan, No. 22-cv-
00174-RB-GBW (D.N.M. Aug. 16, 2022); Sierra Club v. Regan, No. 3:22-cv-
01992-JD (N.D. Cal. Jan. 24, 2023). By stipulation of the parties, that
deadline has now been extended to August 30, 2024. The EPA's duty to
promulgate a FIP for New

[[Page 12683]]

Mexico can only be suspended by the approval of a SIP submission. As
discussed in section IV.B. of this document, the EPA proposes to
disapprove the SIP submission New Mexico subsequently submitted,
described below. This disapproval, if finalized, would not alter or
reset the EPA's pre-existing obligation to promulgate a FIP for New
Mexico.
On July 27, 2021, the New Mexico Environment Department (NMED)
submitted a SIP submission certifying that the State's SIP satisfies
requirements of interstate transport of air pollution for the 2015
ozone NAAQS. On June 9, 2021, on behalf of the City of Albuquerque
Environmental Health Department (EHD), the Cabinet Secretary of NMED
submitted to the EPA a certification that Albuquerque-Bernalillo
County, and New Mexico as a whole, ``does not cause or contribute to
nonattainment or interfere with maintenance of the 2015 ozone NAAQS in
any other state.'' \81\ NMED and EHD's submission contained what NMED
characterized as a weight of evidence analysis of New Mexico's
contribution to ozone transport receptors using the data provided in
the EPA's modeling results included as an attachment to the March 2018
memorandum. New Mexico did not explicitly follow the 4-step interstate
transport framework but did examine downwind air quality and New
Mexico's contributions using the analytic year of 2023 to describe New
Mexico's linkages to receptors. On July 5, 2023, NMED submitted a
supplemental letter containing Exhibit A, for the EPA's consideration
in the Agency's review of the NMED and EHD SIP submissions. The
following sections describe NMED and EHD's submissions, including
Exhibit A, and the information provided for each step in the process.
---------------------------------------------------------------------------

\81\ See EHD SIP submission, attachment B, page 3.
---------------------------------------------------------------------------

a. Information Provided by New Mexico Regarding Step 1
For Step 1 of the 4-step interstate transport framework, NMED and
EHD SIP submissions relied on the EPA's interstate transport modeling
results that are included as an attachment to the March 2018
memorandum.\82\ These EPA modeling results, using a 2011 base year,
provided: (1) projected average design value and maximum design value
for 2023 for ozone monitors to identify nonattainment or maintenance
receptors and (2) projected average contribution from State emissions
to the projected ozone concentrations at each ozone monitor to identify
upwind state-to-downwind receptor linkages.
---------------------------------------------------------------------------

\82\ As explained in section IV.A.2.c., NMED's Exhibit A
acknowledged the EPA's 2016v3 modeling results and linkages.
---------------------------------------------------------------------------

b. Information Provided by New Mexico Regarding Step 2
NMED and EHD's submission presented New Mexico's projected 2023
ozone contributions to maintenance and nonattainment receptors using
the projections from the EPA's March 2018 memorandum. The State
agencies state that in past rulemakings, the EPA has relied upon the 1
percent of the 2015 ozone NAAQS standard (0.70 ppb) contribution
threshold when evaluating if an upwind State has a ``potentially
significant contribution to nonattainment or interference with
maintenance'' \83\ impacts air quality in a downwind state. New Mexico
began their Step 2 analysis by using the EPA's 1 percent threshold to
evaluate contribution and identified that the State contributes 1
percent or more of the NAAQS to one maintenance receptor: Weld County
Tower, Colorado (Monitor ID: 081230009), and one nonattainment
receptor, Rocky Flats-N, Colorado (Monitor ID:
080590006).84 85 Additionally, the EPA's March 2018
memorandum modeling indicated that upwind states contribute roughly 8
and 10 percent of the modeled 2023 design value at the Weld County
receptor and the Rocky Flats-N receptor, respectively.
---------------------------------------------------------------------------

\83\ EHD's SIP submission Attachment B, page 7.
\84\ Id. at Table 1, page 4.
\85\ Id. at page 5.
---------------------------------------------------------------------------

However, NMED and EHD argue that New Mexico does not contribute
significantly to nonattainment or interfere with maintenance at the
Weld County Tower and Rocky Flats-N receptors. NMED and EHD assert that
a ``weight of evidence'' analysis is more appropriate than relying on a
single, national standard for identifying linkages and determining
whether contributions from an upwind State are significant. NMED and
EHD believe that New Mexico should not be linked to Colorado receptors
in the EPA's transport Step 2 analysis because the majority of the
contribution to these receptors comes directly from Colorado. NMED and
EHD attempt to justify this position by relying on a previous transport
rulemaking that determined certain monitoring sites in California were
not interstate transport receptors. Specifically, New Mexico references
the approval of Arizona's 2008 ozone transport SIP submission, see 81
FR 31513. In that action, the EPA determined that Arizona did not
significantly contribute to two California monitoring sites despite
contributing more than 1 percent of the NAAQS, because the EPA found
the total collective contribution from all upwind states was so low at
these sites that they need not be considered transport receptors. New
Mexico attempts to expand the application of the EPA's reasoning in the
Arizona action, asserting it would also be appropriate not to link New
Mexico, or the other linked upwind states, to the Colorado receptors at
the 1 percent threshold.
NMED and EHD's submission also claims that the relative share of
in-state versus out-of-state contribution in Colorado, topographical
influences on the transport of ozone in Colorado, and other air quality
information support its ``weight-of-evidence'' analysis. To identify
the portion of ozone levels in Colorado coming from in-state emissions
as opposed to upwind-state emissions, New Mexico relied on the EPA's
2018 memorandum modeling data. Based on this data, NMED and EHD
determined in-state emissions outweighed the portion of emissions
coming from upwind states collectively.
NMED and EHD considered the topological influences on ozone
concentrations in the Denver area based on information prepared by
Colorado to support the final 2015 ozone NAAQS designation of the
Denver area.\86\ NMED and EHD assert in their submissions that the
receptors in Colorado are predominantly impacted from local sources and
thus the minimal contributions from upwind states do not warrant
further controls in New Mexico. They contend that the topography of the
Denver nonattainment area (NAA) disproportionally favors the formation
of ozone due to local emissions. As support for their argument, NMED
and EHD point to the EPA's TSD supporting the designation of the Denver
NAA: ``The three key circulation patterns (drainage flow, upslope flow,
and mountain-plains solenoid circulation), in conjunction with the
surface topography, in the [Denver] area serve to trap emissions and
produce ozone in the basin formed by the surrounding higher elevation
features. Further, these circulation patterns serve to recirculate
prior day emissions into the Denver area population centers as the
mountain-plains solenoid flow lifts the polluted atmosphere up the
mountain slopes of the Rocky Mountains to the west in warm afternoons,
and then returns the polluted air to the surface as the lofted air
circulates back to the east and

[[Page 12684]]

subsides overnight.'' \87\ New Mexico presents this information to
further support their claim that the Denver NAA is significantly more
impacted by emissions from within Colorado than from interstate
transport.
---------------------------------------------------------------------------

\86\ Id. at page 17. See also 83 FR 25776 (June 4, 2018).
\87\ See <a href="https://www.epa.gov/sites/default/files/2018-05/documents/co_tsd_final_0.pdf">https://www.epa.gov/sites/default/files/2018-05/documents/co_tsd_final_0.pdf</a>.
---------------------------------------------------------------------------

NMED and EHD's final weight of evidence factor consisted of an
assessment of ozone air quality monitoring data and design values.
Here, they identify downward trends in ozone precursor emissions
(NO<INF>X</INF> and VOC) from 2005 to 2018. NMED and EHD cite New
Mexico's current on-the-books rules as sufficient to resolve the
State's transport responsibilities and as reason to believe downward
trends in emissions and ozone concentrations at the receptors for which
they contribute greater than 0.70 ppb (Rock Flats-N and Well County
Tower monitors) will continue to decrease. NMED included data on an
overall trend of slightly increasing VOC emissions and decreasing
NO<INF>X</INF> emissions in New Mexico, Utah, Wyoming, California, and
Texas from 2002 to 2014. New Mexico also provided data exhibiting a
decrease of VOC and NO<INF>X</INF> emissions from Colorado during the
same time period. New Mexico credited the downward emissions trends to
permanent and enforceable control measures. New Mexico made an argument
that overall decreasing ozone concentrations and emissions trends in
the state, and other upwind states, correlate with reduced
contributions to nonattainment and maintenance receptors outside of New
Mexico. NMED and EHD concluded that decreasing ambient ozone
concentrations in Colorado is indicative of New Mexico contributing
less to ozone in downwind states as time goes on.
This concluded New Mexico's analysis in its original submission.
New Mexico did not conduct an analysis of emissions-control
opportunities within the State at Step 3. NMED and EHD concluded it
would be unreasonable for New Mexico to take further actions to address
its obligations under the good neighbor provisions for the ozone NAAQS.
Thus, at Step 4, NMED and EHD determined that no additional permanent
and enforceable measures were necessary to reduce the State's
emissions.
c. New Mexico Letter
On July 5, 2023, NMED submitted for the EPA's consideration a
letter with an attachment, Exhibit A. The letter indicates its
submission is in response to the EPA's indication that it may
disapprove New Mexico's SIP submission. To the EPA's awareness, this
letter was not subject to public notice or rulemaking process at the
State level and does not in itself purport to be a SIP submission or a
revision to New Mexico's SIP. As such, the EPA takes the information in
the letter under advisement but does not consider this letter to be a
new SIP submission in its own right or part of the SIP submission dated
July 27, 2021.
In its letter, NMED asserts the EPA should account for emissions
reductions that have occurred since 2020 that could resolve the State's
transport obligations. NMED identified emissions reductions from two
current compliance orders that resulted in a reduction of 236 tons of
annual NO<INF>X</INF> emissions. NMED entered into a settlement
agreement with ETC Texas Pipeline Ltd (ETC) for its Jal #3 plant,
compliance order No. AQB 20-63, which was lodged on August 25, 2021.
The settlement agreement mandated that the facility remove its sulfur
recovery unit, which resulted in an emissions reduction of 4.8 tons of
NO<INF>X</INF> per year. Additionally, NMED entered into a consent
decree with ETC for its Eunice Gas Plant, compliance order No. AQB 20-
64, which was lodged on September 9, 2021. The consent decree required
the shutdown of the Eunice plant, except for Amanda Booster Station,
resulting in emissions decrease of 231.4 tons of NO<INF>X</INF> per
year. Lastly, NMED references emissions reductions anticipated from the
consent decree lodged with Matador Production Company, filed on March
27, 2023. NMED is anticipating emissions reductions of a total 77 tons
of NO<INF>X</INF> over 3 years and to occur before 2030.
NMED argues that the emissions reductions resulting from these
compliance orders are satisfactory to fulfil the emissions reductions
that would occur under the Federal Good Neighbor Plan for the 2015
Ozone Standard. NMED states that based on the formula applied under the
Federal Good Neighbor Plan, the EPA identified 30 tons of emissions
reductions achievable in 2023 under the current formula for EGU
emissions reductions.\88\ NMED claims that the ``EPA indicated that
this 30 ton per year reduction would be all that is necessary to meet
its good neighbor FIP requirements.'' \89\ NMED argues that as the
NO<INF>X</INF> emissions decreases outlined in the provided consent
decrees are greater than the emissions reductions anticipated in the
Federal Good Neighbor Plan, the State will have met its obligations for
interstate transport.
---------------------------------------------------------------------------

\88\ Ozone Transport Policy Analysis Final Rule Technical
Support Document. Table B-3. 2024 Ozone Season NO<INF>X</INF>
Emissions for States at Different Uniform Control Scenarios.
\89\ NMED's July 5, 2023, letter to the EPA, at 1.
---------------------------------------------------------------------------

3. Tennessee
On September 13, 2018, Tennessee submitted a SIP revision
addressing the CAA section 110(a)(2)(D)(i)(I) interstate transport
requirements for the 2015 8-hour ozone NAAQS.90 91 The SIP
submission provided Tennessee's analysis of its impact to downwind
states and concluded 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. Tennessee's submission
relied on the EPA's modeling results for 2023 using a 2011 base year,
contained in the March 2018, memorandum, to identify downwind
nonattainment and maintenance receptors that may be impacted by
emissions from sources in the State at Steps 1 and 2 of the 4-step
interstate transport framework.\92\ The Tennessee Department of
Environmental Control (TDEC) reviewed the EPA's 2023 modeling,
concurred with the results, and determined that the EPA's future year
projections were reasonable and account for source shutdowns, new
controls, and fuel switches. TDEC summarized the State's upwind
contribution to 26 nonattainment and maintenance receptors and noted
that according to the modeling, Tennessee's largest impact on any
potential downwind receptor in 2023 would be 0.31 ppb to a
nonattainment receptor and 0.65 ppb to a maintenance receptor.
Tennessee concluded that emissions from Tennessee do not contribute
above 1 percent of the NAAQS or above 1 ppb at any receptors.
---------------------------------------------------------------------------

\90\ The September 13, 2019, SIP submission provided by TDEC was
received by the EPA on September 17, 2018.
\91\ On September 18, 2018, Tennessee submitted multiple SIP
revisions under one cover letter. The EPA is only acting on
Tennessee's 2015 ozone good neighbor interstate transport SIP
requirements in this document.
\92\ The EPA notes that Tennessee's SIP submission is not
organized around the EPA's 4-step interstate transport framework for
assessing good neighbor obligations, but the EPA summarizes the
submission using that framework for clarity here.
---------------------------------------------------------------------------

Tennessee's submission asserted that NO<INF>X</INF> emissions are
considered the primary cause of formation of ozone in the southeast
United States, and emphasized a significant reduction in NO<INF>X</INF>
emissions reductions from coal-fired EGUs and other large
NO<INF>X</INF> sources leading to improvements in air quality,
including reductions attributable to

[[Page 12685]]

previous transport rulemakings.\93\ Additionally, TDEC identifies
existing SIP-approved provisions, Federal regulations and programs,
court settlements, and statewide source shutdowns that TDEC believes
limit ozone precursor emissions in the State.\94\
---------------------------------------------------------------------------

\93\ The Tennessee SIP revision specifically cites the
NO<INF>X</INF> Budget Trading Program, CAIR, and CSAPR. In addition,
the Tennessee SIP revision discusses Tennessee rule 1200-03-27-.12
(NO<INF>X</INF> SIP Call requirements for Stationary Boilers and
Combustion Turbines), which had not been approved into the SIP at
the time of the September 13, 2018, submission. The EPA finalized
approval of TAPR 1200-03-27-.12 into the Tennessee SIP on March 2,
2021. See 86 FR 12092.
\94\ See page 9 through 12 of Tennessee's September 13, 2018,
SIP submission for a list of SIP-approved State rules and Federal
rules. This can be found in Docket No. EPA-R04-OAR-2021-0841.
---------------------------------------------------------------------------

Based on the information contained in Tennessee's transport SIP
submission, TDEC concluded that Tennessee does not significantly
contribute to nonattainment or interfere with maintenance in another
State of the 2015 8-hour ozone NAAQS, and that the SIP submission
provides for adequate measures to control ozone precursor emissions.
Prior Notices Related to Tennessee's SIP Submission
Previously, the EPA proposed approval of Tennessee's September 13,
2018, SIP submission, based on the contribution modeling provided in
the March 2018 memorandum. See 84 FR 71854 (December 30, 2019). When
the EPA completed updated modeling of the 2023 analytic year in 2020
using a 2016-based emissions modeling platform (2016v1), however, it
became evident that Tennessee was projected to be linked to downwind
nonattainment and maintenance receptors.\95\ As a result, the EPA did
not act on Tennessee's SIP submission when it 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).
---------------------------------------------------------------------------

\95\ See ``Air Quality Modeling Technical Support Document for
the Final Revised Cross-State Air Pollution Rule Update'', available
in Docket ID No. EPA-HQ-OAR-2021-0663.
---------------------------------------------------------------------------

The 2016v2 modeling comported with the 2016v1 modeling results for
Tennessee, in that it continued to show Tennessee was linked to at
least one downwind-maintenance-only receptor in 2023. Based on this
information and the EPA's evaluation of the information and arguments
put forward by the State in its submission, the EPA withdrew its
December 30, 2019, proposed approval of Tennessee's September 13, 2018,
interstate transport SIP submission, and the EPA proposed disapproval
of Tennessee's submission. See 87 FR 9545 (February 22, 2022).
As described in section III.C. of this document, the EPA received
numerous comments on the 2016v2 modeling used in its proposed ozone
transport actions, including its proposed disapproval of Tennessee's
submission. The EPA incorporated this feedback and made several updates
to the 2016v2 inventories and model design to construct a 2016v3
emissions platform, which the EPA used to develop the 2016v3 air
quality modeling. The EPA used the 2016v3 modeling to support the final
action on 21 interstate transport SIP submissions for the 2015 ozone
NAAQS.96 97 The Agency also found there were additional
receptors that would struggle to attain or maintain the NAAQS in 2023,
which it identified as violating-monitor receptors. The final air
quality analysis modeling indicated that while Tennessee was no longer
projected in the modeling to be linked to any nonattainment or
maintenance receptors, the State was linked above 1 percent of the
NAAQS to five violating-monitor receptors, all located in Texas. See
2016v3 AQM TSD, at C-5.
---------------------------------------------------------------------------

\96\ Disapproval Action, 88 FR 9336 (February 13, 2023), and
Federal Good Neighbor Plan, 88 FR 36654 (June 5, 2023).
\97\ Details on the 2016v3 air quality modeling and the methods
for projecting design values and determining contributions in 2023
and 2026 are described in the TSD titled ``Air Quality Modeling
Final Rule TSD--2015 Ozone NAAQS Good Neighbor Plan,'' hereafter
known as the Final Good Neighbor Plan AQM TSD.
---------------------------------------------------------------------------

Although the EPA identified a linkage between emissions in
Tennessee and violating-monitor receptors, in recognition that it had
not included such receptors in its proposed action, the EPA did not
take final action on Tennessee's transport SIP submission at that time.
The EPA is now withdrawing its proposed disapproval of Tennessee's
September 13, 2018, interstate transport SIP submission as published on
February 22, 2022, at 87 FR 9545.

B. EPA Evaluation

The EPA is proposing to find that SIP submissions from Arizona, New
Mexico, and Tennessee meet the states' obligations with respect to
Prong 1, prohibiting emissions that contribute significantly to
nonattainment of the 2015 8-hour ozone NAAQS, but do not meet
obligations with respect to Prong 2, interference with maintenance of
the 2015 8-hour ozone NAAQS in any other state. This proposal is based
on the EPA's evaluation of each State's SIP submission, considered in
light of the state-of-the-science 2016v3 modeling for 2023 and 2026,
the certified ozone monitoring data and design values for 2021 and
2022, and corresponding contribution analysis. Therefore, the EPA is
proposing to partially approve with respect to Prong 1 and partially
disapprove with respect to Prong 2 the SIP submissions from Arizona,
New Mexico, and Tennessee.
1. Arizona
a. Evaluation of Information Provided by Arizona Regarding Steps 1 and
2
In Arizona's 2018 SIP Submission, the State cites the EPA modeling
released in the March 2018 memorandum to conclude that Arizona does not
contribute significantly (i.e., equal to or above the 0.70 ppb
threshold) to any nonattainment or maintenance receptor in another
state.\98\ In this proposal, the EPA relies on the Agency's 2016v3
modeling, which uses a more recent base year and more up-to-date
emissions inventories, compared to the modeling that was released in
the March 2018 memo. The 2016v3 modeling along with the violating-
monitor receptor methodology are used to identify downwind receptors,
calculate upwind contributions, and determine ``linkages'' to downwind
air quality problems in 2023 using the 0.70 ppb threshold (i.e., 1
percent of the NAAQS). As shown in Tables IV.B-1-3, the updated EPA
contribution modeling identifies Arizona's maximum contribution to a
downwind nonattainment or maintenance receptor to be greater than 1
percent of the standard (i.e., greater than 0.70 ppb). Because the
entire technical basis for Arizona's determination with respect to CAA
section 110(a)(2)(D)(i)(I) in its 2018 SIP Submission is that Arizona
is not linked at Step 2, the EPA proposes to partially disapprove
Arizona's SIP submission with respect to Prong 2, interference with
maintenance, based on the EPA's finding that such a linkage does exist
to maintenance-only receptors.
---------------------------------------------------------------------------

\98\ Arizona's 2018 iSIP submission, 13-14.
---------------------------------------------------------------------------

b. Results of the EPA's Step 1 and Step 2 Modeling and Findings for
Arizona
As described in section III.B. of this document, the EPA performed
air quality modeling using the 2016v3 emissions platform to project
design values and contributions for 2023 and 2026. These data were
examined to determine if Arizona contributes at or above the threshold
of 1 percent of the 2015 ozone NAAQS (0.70 ppb) to any downwind
nonattainment or maintenance receptor. As shown in Table IV.B-1, the
data indicate that, in

[[Page 12686]]

2023, emissions from Arizona contribute greater than 1 percent of the
2015 ozone NAAQS to six maintenance-only receptors in Colorado, Nevada,
New Mexico, and Texas.\99\ Table IV.B.1-3 indicates that in 2023,
emissions from Arizona contribute greater than 1 percent of the NAAQS
to three violating-monitor maintenance-only receptors in Nevada and New
Mexico. Furthermore, data for 2026 in Table IV.B.1-2 indicate that
emissions from Arizona contribute greater than 1 percent of the 2015
ozone NAAQS to five maintenance-only receptors in Colorado and New
Mexico.\100\ In addition, Arizona's contribution exceeds 1 ppb at five
receptors in 2023 and two receptors in 2026. Thus, whether Arizona
could have sought to justify an alternative 1 ppb threshold is
irrelevant to EPA's determination that Arizona is linked, as Arizona's
contributions to receptors exceed even that higher alternative
contribution threshold.
---------------------------------------------------------------------------

\99\ Final Good Neighbor Plan AQM TSD, Appendix C, available in
Docket ID No EPA-HQ-OAR-2021-0668.
\100\ Id.

Table IV.B.1-1--Arizona Linkage Results Based on the EPA Updated 2023 Modeling
----------------------------------------------------------------------------------------------------------------
2023 Average 2023 Maximum Arizona
Receptor ID Location Nonattainment/ design value design value contribution
maintenance (ppb) (ppb) (ppb)
----------------------------------------------------------------------------------------------------------------
80690011..................... Larimer, Maintenance- 70.9 72.1 0.86
Colorado. Only.
350130021.................... Do[ntilde]a Maintenance- 70.8 72.1 1.04
Ana, New Only.
Mexico.
350130022.................... Do[ntilde]a Maintenance- 69.7 72.4 1.06
Ana, New Only.
Mexico.
350151005.................... Eddy, New Maintenance- 69.7 74.1 1.34
Mexico. Only.
350250008.................... Lea, New Mexico Maintenance- 69.8 72.2 1.66
Only.
481410037.................... El Paso, Texas. Maintenance- 69.8 71.4 1.69
Only.
----------------------------------------------------------------------------------------------------------------
Source: Final Good Neighbor Plan AQM TSD.

Table IV.B.1-2--Arizona Linkage Results Based on the EPA Updated 2026 Modeling
----------------------------------------------------------------------------------------------------------------
2026 Average 2026 Maximum Arizona
Receptor ID Location Nonattainment/ design value design value contribution
maintenance (ppb) (ppb) (ppb)
----------------------------------------------------------------------------------------------------------------
80690011..................... Larimer, Maintenance- 70.0 71.2 0.71
Colorado. Only.
350130021.................... Do[ntilde]a Maintenance- 69.9 71.2 0.82
Ana, New Only.
Mexico.
350130022.................... Do[ntilde]a Maintenance- 69.0 71.6 0.82
Ana, New Only.
Mexico.
350151005.................... Eddy, New Maintenance- 69.1 73.4 1.06
Mexico. Only.
350250008.................... Lea, New Mexico Maintenance- 69.2 71.6 1.34
Only.
----------------------------------------------------------------------------------------------------------------
Source: Final Good Neighbor Plan AQM TSD.

Table IV.B.1-3--Arizona 2023 Linkage Results Based on Violating-Monitor Maintenance-Only Receptors
--------------------------------------------------------------------------------------------------------------------------------------------------------
Arizona
Receptor ID Location 2021 Design 2022 Design 2021 4th high 2022 4th high contribution
value (ppb) value (ppb) (ppb) (ppb) (ppb)
--------------------------------------------------------------------------------------------------------------------------------------------------------
320030043................................. Clark, Nevada............... 73 75 74 74 0.77
350011012................................. Bernalillo, New Mexico...... 72 73 76 74 1.62
350130008................................. Do[ntilde]a Ana, New Mexico. 76 71 79 78 1.13
--------------------------------------------------------------------------------------------------------------------------------------------------------
Source: Final Good Neighbor Plan AQM TSD.

Therefore, based on the EPA's evaluation of the information
submitted by Arizona, and based on the EPA's most recent modeling
results for 2023 and 2026 using the 2016v3 emissions platform, the EPA
proposes to find that Arizona is not linked to any nonattainment
receptor. However, the EPA finds that Arizona is linked at Steps 1 and
2 to at least one, and in fact several, maintenance-only receptors,
based on the available analytical information, which includes the
modeling results from the 2016v3 platform and the violating-monitor
receptor analysis.
c. Evaluation of Information Provided Regarding Step 3
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), 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. The EPA recognizes that the modeling results released
with the March 2018 memorandum indicated Arizona would not contribute
at or above 1 percent of the NAAQS to any downwind receptor. Arizona's
2018 SIP Submission therefore concluded that it was not necessary to
identify any emissions reductions or adopt any permanent and
enforceable controls to meet the good neighbor provision for the 2015
ozone NAAQS.\101\ Arizona's 2018 SIP Submission states that ``Arizona
believes that this SIP contains adequate provisions to ensure that air
emissions in Arizona do not significantly contribute to nonattainment
or interfere with maintenance of the 2015 ozone NAAQS in any other
State in the future.'' \102\
---------------------------------------------------------------------------

\101\ Arizona's 2018 iSIP Submission, 13-14.
\102\ Id at 14.
---------------------------------------------------------------------------

However, as discussed previously in this section, the EPA's more
recent air quality analysis for 2023 and 2026

[[Page 12687]]

indicates that sources in Arizona are in fact contributing to downwind
air quality problems at several maintenance-only receptors. Based on
this record, the EPA finds the State's conclusion that its SIP contains
adequate provisions prohibiting emissions interfering with maintenance
of the 2015 ozone NAAQS in other states to lack justification, and the
EPA proposes to partially disapprove the submission.
d. Conclusion
For the reasons described in this section, the EPA proposes to
partially approve Arizona's SIP submission with respect to Prong 1 of
CAA section 110(a)(2)(D)(i)(I) and to partially disapprove Arizona's
SIP submission with respect to Prong 2 of CAA section
110(a)(2)(D)(i)(I).
2. New Mexico
a. Evaluation of Information Provided by New Mexico Regarding Step 1
As noted earlier, NMED and EHD first relied on the modeling
information from the EPA's March 2018 memorandum which used a 2011 base
period with 2011 meteorology to identify nonattainment and maintenance
receptors and upwind-state contribution levels at those receptors. NMED
and EHD acknowledged that this modeling showed a linkage to one
nonattainment and one maintenance-only receptor in the Denver area at
or above 0.70 ppb. Since the time of the State's submission, the EPA
updated the modeling to a 2016 base period with 2016 meteorology and
updated emissions data to produce new 2023 model projections and
released this new modeling in 2022 (commonly referred to as 2016v2
modeling platform). As explained in section III.C. of this document, in
response to comments, the EPA further refined its modeling in the
2016v3 modeling platform, issued in 2023.\103\ Under both the EPA's
2011-based modeling included in the March 2018 memorandum that New
Mexico relied upon in their SIP submission and the EPA's updated 2016v3
modeling, there are receptors identified, to which New Mexico is linked
above 1 percent of the NAAQS, as described in the next section.\104\
---------------------------------------------------------------------------

\103\ Air Quality Modeling Final Rule Technical Support
Document--2015 Ozone NAAQS Good Neighbor Plan in Docket ID No. EPA-
R08-OAR-2023-0375.
\104\ The 2011 modeling relied on by NMED and EHD in the SIP
submission identified linkages to one nonattainment receptor, the
Rocky Flats-N receptor, and the one maintenance receptor, the Weld
County Tower receptor, in 2023. See NMED SIP Submission at 4.
---------------------------------------------------------------------------

b. Evaluation of Information Provided by New Mexico Regarding Step 2
As in Step 1, NMED and EHD relied upon the modeling released in the
EPA's March 2018 memo, and in its July 2023 letter, NMED relied on the
EPA's 2016v3 modeling results to analyze projected contributions to
downwind receptors. As explained in section IV.A.2. of this document,
while NMED and EHD acknowledge the EPA's modeling results identifying a
contribution greater than 0.70 ppb, the agencies do not find it
appropriate to rely on a particular threshold (i.e., 0.70 ppb) at Step
2 to determine whether a State is linked (or significantly
contributing) to a downwind receptor in the West, but instead they rely
on a weight of evidence approach. NMED and EHD point to the EPA's past
approval of Arizona's 2008 ozone good neighbor SIP submission, in which
the EPA approved Arizona's SIP based on an evaluation of receptors in
California to support the use of a weight of evidence approach in
evaluating interstate transport and claim that the EPA determined a
weight of evidence approach to be an appropriate evaluation to apply in
the West.\105\
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\105\ NMED SIP submission at 5.
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Although NMED and EHD's approach to evaluating whether an upwind
State is linked to a downwind receptor differs from the EPA's broadly
applied 4-step interstate transport framework by relying instead on a
``weight of evidence'' approach, here, we evaluate that ``weight of
evidence'' methodology NMED has chosen to apply. While the NMED and EHD
submission does not claim to establish a linkage, and instead
postulates that it is inappropriate to apply a uniform standard to
determine whether a State's contributions should be further evaluated
in Step 3, the submission does rely on a 1 percent threshold to
identify which receptors to apply a weight of evidence analysis.
Therefore, while the NMED and EHD submission seems to disagree in
principle with the use of a single threshold at Step 2, they have
effectively moved to apply the same threshold for the same purpose the
EPA would do at Step 2--rely on a 1 percent threshold to identify
receptors to which a State is linked and therefore require further
evaluation at Step 3 to determine whether any of the State's
contributions, if any, are significant.
While the EPA does not disagree with the methodology NMED and EHD
used in the submission to identify receptors where the State is linked,
the EPA continues to find its 4-step interstate transport framework to
be an appropriate and nationally consistent approach to evaluating
interstate transport, including the application of a contribution
threshold at Step 2 of the framework. As stated in the EPA's final SIP
disapproval action, the EPA disagrees with the NMED and EHD submission
that neither its nationwide photochemical grid modeling nor the 4-step
interstate transport framework for ozone can generally be applied to
states in the western region of the U.S., including contributions from
sources in New Mexico, and has maintained that position consistently
throughout numerous actions.\106\
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\106\ For a discussion of this history, see for example 87 FR
31480-81 (proposed disapproval of Utah SIP submission) and 87 FR
31453-56 (proposed disapproval of California SIP submission).
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The NMED and EHD submission cites the EPA's action on Arizona's
2008 ozone good neighbor SIP as evidence that the EPA relied on a
weight of evidence approach when evaluating interstate transport in the
West. In that action, the EPA considered the collective contribution
from upwind states to monitoring sites in California as part of the
basis for approval of the State's submission, despite linkages over 1
percent from Arizona to a select few California monitoring sites. The
EPA disagrees that New Mexico's contribution to Colorado is comparable
to the situation addressed in the Arizona 2008 ozone good neighbor
action. The facts that supported the EPA's conclusion on Arizona's 2008
ozone good neighbor SIP were unique; in the Disapproval action and
Federal Good Neighbor Plan, the EPA has already explained that it
rejects that a comparable consideration is relevant for receptors in
Colorado, which the EPA has consistently found are impacted by the
collective contribution of numerous upwind states at levels that well
exceed the circumstances of the California sites. See 88 FR at 9378-79
(western State policy generally); id. at 9360 (rejecting similar
arguments in disapproving SIP submission from Utah); see also Response
To Comments Document, EPA-HQ-OAR-2021-0663, at 236-237. At times the
EPA has found it appropriate to examine more closely discreet issues
for some western states; \107\ however, the EPA has consistently
applied the 4-step interstate transport framework in western states, as
it proposes to do in this action, and

[[Page 12688]]

has previously identified ozone transport problems in the West,
including in Colorado, that are similar to those in the east.\108\
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\107\ See, e.g., 87 FR 61249, 61254-55 (October 11, 2022) (in
approving Colorado's interstate transport SIP for the 2015 ozone
NAAQS, analyzing unique issues associated with wintertime inversion
conditions in certain western areas).
\108\ See, e.g., 87 FR 31443, 31453-57 (May 24, 2022); 83 FR
65093, 65094 (December 19, 2018); 82 FR 9155, 9157 (February 3,
2017); 82 FR 9142, 9149-50 (February 3, 2017); 81 FR 74504, 74523
(October 26, 2016); 81 FR 71991, 71993-95 (October 19, 2016).
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New Mexico claims that the Weld County Tower and Rocky Flats-N
receptors are impacted by the same magnitude of contributions from
interstate transport as the California receptors were in the approval
of the Arizona transport SIP submission. This, however, is not
represented in the data presented in NMED and EHD's submittals. Total
upwind contributions were 10 percent and 8 percent of the projected
2023 design values at the Rocky Flats-N and Weld County Tower
receptors, respectively, and five states were determined to be linked
at or above 1 percent of the NAAQS. The results show that the upwind
contributions to Colorado are significantly greater than the upwind
contributions to the monitors evaluated in California when taking
action on Arizona's 2008 ozone NAAQS SIP submission, where the total
contribution from all upwind states was 2.5 percent and 4.4 percent of
the total ozone concentration at the two monitoring sites in California
to which Arizona contributed greater than 1 percent.
The determination made to remove the identified California
receptors from the Step 1 analysis, done in the context of the less
protective 2008 ozone NAAQS, was a narrow circumstance that does not
apply in the vast majority of receptors outside of California. The data
presented by New Mexico suggests the circumstances that led the EPA to
remove California receptors from Step 1 do not apply to receptors in
Colorado. In previous rulemakings, for example, the EPA has, in fact,
determined that receptors in Colorado are heavily impacted by upwind-
state contribution. See, e.g., 82 FR 9155 (Feb. 3, 2017); 81 FR 71991
(October 19, 2016). The EPA affirms, contrary to NMED's assertion, that
the Colorado receptors that NMED analyzed are impacted by upwind State
contributions.\109\ In fact, nowhere outside California do we project
that there will be receptors having such a low total upwind
contribution as is the case for California.\110\ Further, at the El
Paso UTEP receptor (Monitor ID: 481410037) which, as shown in Table
IV.B.2-1, is the receptor to which emissions from sources in New Mexico
are linked, there are 2 states linked above 1 percent of the standard
and 6 percent of the ozone design values is due to the collective
contribution from upwind states.
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\109\ Air Quality Modeling Final Rule Technical Support
Document--2015 Ozone NAAQS Good Neighbor Plan in Docket ID No. EPA-
HQ-OAR-2021-0668.
\110\ See 88 FR at 36718 regarding contribution to certain
monitoring sites in California and its relation to the EPA's
approval of Arizona's 2008 ozone NAAQS transport SIP submittal.
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c. Results of EPA's Step 1 and Step 2 Modeling and Findings for New
Mexico
As described in section I. of this document, the EPA has performed
updated air quality modeling using the 2016v3 emissions platform to
project design values and contributions for 2023. These data were
examined to determine if the newer modeling also indicated that New
Mexico contributes at or above the threshold of 1 percent of the 2015
ozone NAAQS (0.70 ppb) to any downwind nonattainment or maintenance
receptor. As shown in IV.B.2-1, the data \111\ indicates that in 2023,
emissions from New Mexico contribute greater than 1 percent of the
standard to a maintenance-only receptor in El Paso, Texas.\112\ New
Mexico is not linked to any violating-monitor receptors in 2023. Based
on the 2016v3 modeling, the average and maximum design values for the
El Paso monitor in 2026 are below the level of the 2015 ozone NAAQS. In
this regard, New Mexico is not projected to be linked to any receptors
in 2026.
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\111\ Design values and contributions at individual monitoring
sites nationwide are provide in the file:'' 2016v3_Final
FIP_DVs_state_contributions.xlsx'' which is included in docket ID
No. EPA-HQ-OAR-2021-0668.
\112\ 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 New Mexico 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 IV.B.2-1--New Mexico Linkage Results Based on the EPA's Updated 2016v3 2023 Modeling
--------------------------------------------------------------------------------------------------------------------------------------------------------
2023 Average 2023 Maximum New Mexico
Receptor ID Location Nonattainment/maintenance design value design value contribution
(ppb) (ppb) (ppb)
--------------------------------------------------------------------------------------------------------------------------------------------------------
481410037.................................. El Paso, TX................. Maintenance................. 69.8 71.4 1.59
--------------------------------------------------------------------------------------------------------------------------------------------------------

Therefore, based on the EPA's evaluation of the information
submitted by NMED and EHD, and based on the EPA's most recent modeling
results for 2023 and 2026 using the 2016v3 emissions platform, the EPA
proposes to find that New Mexico is not linked to a nonattainment
receptor. However, the EPA finds that New Mexico is linked at Steps 1
and 2 to a maintenance-only receptor in 2023. Therefore, the EPA will
proceed to evaluate NMED and EHD's SIP submission at Step 3 of the 4-
step interstate transport framework as it pertains to Prong 2,
interference with maintenance of the 2015 ozone NAAQS.
d. Evaluation of Information Provided Regarding Step 3
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), 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. NMED and EHD's initial SIP submission did not conduct
an analysis of emissions control opportunities within the state,
applying either the EPA's multifactor analysis at Step 3 or using any
other framework of analysis. Instead, the submission presents a three-
part ``weight of evidence'' analysis to determine no reductions are
needed beyond existing emissions reductions efforts to satisfy the
State's obligations with regards to the good neighbor provision.
NMED's July 2023 letter uses mass-based emissions reductions
identified on an ozone-season wide basis derived from the Step 3 (and
Step 4 analysis for EGUs) completed by the EPA in the Federal Good
Neighbor Plan to identify the magnitude of emissions that NMED assumes
constitutes the identification of ``significant contribution'' that
must be eliminated to address the State's good

[[Page 12689]]

neighbor obligations. NMED's letter asserts that certain compliance
orders entered in recent years would achieve an equivalent or greater
amount of NO<INF>X</INF> emissions reduction (on a mass-basis) than the
Federal Good Neighbor Plan is projected to require from EGUs in New
Mexico.
In this section, we evaluate the State's weight of evidence
analysis submitted in the SIP submission, and then in the following
section (Section IV.B.2.e of this document) address the argument put
forward by NMED in the July 2023 letter.
As summarized in section IV.A.2. of this document, NMED and EHD's
weight of evidence consisted of three parts, (1) a comparison of in-
state emissions contributions and out-of-state contributions to the
receptors with linkages from New Mexico, (2) consideration of
topography and airflow associated with local ozone formation in the
Denver area, and (3) an evaluation of trends in emissions and ozone
concentrations at receptors with linkages and western states.
Regarding the first weight of evidence comparing in-state and out
of State emissions, the EPA disagrees that these factors are sufficient
to establish that New Mexico's emissions do not significantly
contribute to receptors in any other state. While NMED and EHD point to
a relatively higher level of contributions from non-anthropogenic,
local, or international contributions in the West as reason for
evaluating interstate transport differently in the West, a State is not
excused from eliminating its significant contribution due to
contributions from these sources, where the data show that
anthropogenic emissions from upwind states also contribute to
identified receptors at levels that indicate an interstate contribution
problem as well. As stated in section V.C.2. of the EPA's final SIP
Disapproval action, a State is not excused from eliminating its
significant contribution on the basis that international emissions also
contribute some amount of pollution to the same receptors to which the
State is linked. This same principle applies broadly to other arguments
as to which emissions are the ``cause'' of the problem; the good
neighbor provision established a contribution standard, not a ``but-
for'' causation standard. See Wisconsin, 938 F.3d at 323-25. The EPA's
position on this issue is established in the SIP Disapproval action.
See 88 FR at 9378 (rejecting this argument as to international
contribution); Disapproval action RTC at 455-58 (rejecting this
argument as to in-state contribution); id. at 459-62 (rejecting this
argument as to non-anthropogenic contribution). Nor did New Mexico
offer a test or standard by which these considerations could be applied
on a principled basis to establish when, if they were relevant
considerations, they would justify a different approach for any
particular state. New Mexico only argued that these considerations
should excuse its own obligations.
The submission's second weight of evidence factor considers the
Denver area's topography and air flow direction. The EPA has evaluated
the information in the submission and proposes to determine that this
evidence does not provide sufficient reason to support NMED and EHD
submission's conclusion that the contributions from New Mexico to the
receptors identified by the EPA's modeling is not significant. The NMED
and EHD submission claims that the EPA had concluded that geographical
features (mountains, etc.) in and around the Denver NAA ``magnify and
constrain the influence of local emissions on air quality'' and ozone
production by citing the EPA's description of the region in the EPA's
designation of the Denver NAA for the 2015 ozone standard.
The EPA evaluated this argument thoroughly in the SIP Disapproval
action. The EPA explained, despite the local geographical features in
and around the Denver NAA substantial portion of the transport problem
at these receptors, on the order of 6-10 percent (depending on
individual receptor and modeling version used) is the result of
transport from states outside of Colorado. The EPA evaluated the
performance of its 2016v3 modeling in all areas of the country,
including in Colorado and in the southwest (where New Mexico is linked
to an El Paso receptor), and the Agency found the modeling performed
within parameters and is reliable for use to inform determinations of
contribution, even in areas of unique western topography. See RTC 171-
184. These same findings hold true for New Mexico's linkage, whether
assessed in relation to its contribution to Colorado receptors in the
2011-based modeling, or in the linkage to El Paso found in 2016v3
modeling.
The third weight of evidence provided in the SIP consists of
monitoring data and emissions data to justify their conclusion that no
additional emissions reductions would be necessary to satisfy New
Mexico's ozone transport obligations.
The NMED and EHD submission points to a projected downward trend of
ozone levels at monitors within the Colorado nonattainment area from
2008 to 2018, and VOC and NO<INF>X</INF> emissions reductions from 2002
to 2014 in states contributing above 1 percent of the NAAQS to the Weld
County or Rocky Flats-N receptors. The submission did not quantify the
total anticipated reductions in NO<INF>X</INF> and VOC emissions from
New Mexico's existing regulatory requirements nor did it evaluate the
impact of those reductions in downwind air quality at the Denver area
receptors to which New Mexico was projected to be linked in the 2011-
based modeling. In general, the air quality modeling that the EPA has
conducted already accounts for ``on-the-books'' emissions control
measures, including the expected reductions those measures achieve
through 2023. The 2016v3 modeling, which contains updated emissions
inventories for New Mexico and other states, established a continued
linkage from New Mexico to at least one downwind receptor in 2023 at
Steps 1 and 2, despite emissions control efforts in the State.\113\
Applying the submission's same logic in this weight of evidence to the
linkage identified in the EPA's 2016v3 modeling, the El Paso County,
Texas, receptor, the EPA identifies a similar flaw. Because a linkage
continues to occur under projected baseline emissions levels, the next
analytical step would be to conduct an analysis of emissions control
opportunities in the State to determine what, if any, emissions may
constitute ``significant contribution'' and therefore should be
prohibited. The EPA explained in the SIP Disapproval action that an
alternative approach of simply relying on emissions trends data,
without including those claimed reductions as enforceable control
measures within a SIP, is insufficient. 88 FR at 9354, 9356, 9378-79;
Response To Comments at 329-33. Similarly, emissions trends do not
themselves provide a principled basis for determining what ``amount''
of emissions constitutes ``significant contribution.'' See 88 FR at
9375-76.
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\113\ As the EPA explained in the final SIP Disapproval action,
the EPA views changes in linkages between 2011-based meteorology and
2016-based meteorology not as an indication of uncertainty in
whether a State is linked at Step 2 but rather as confirmation that
the State's emissions are substantial enough to generate linkages
under alternative meteorological data sets. As such, the changes in
linkage observed between the 2011-based and 2016v3 modeling for New
Mexico does not alter the EPA's findings or justify a less rigorous
analysis at Step 3--just as the EPA found for many other states in
connection with the Disapproval action. See 88 FR at 9367.
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Based on this evaluation of the weight of evidence analysis
provided in NMED and EHD's SIP submission, the EPA finds that the
analysis is insufficient to support the conclusion that the State

[[Page 12690]]

does not interfere with maintenance at receptors in other states. The
EPA's updated air quality analysis indicates New Mexico is not linked
to any nonattainment receptors but is linked to a maintenance-only
receptor in El Paso, Texas. Thus, the EPA proposes partial disapproval
of New Mexico's submission with respect to Prong 2.
e. NMED's July 2023 Letter
The EPA has considered the additional information New Mexico
provided in its July 2023 letter. At the outset, we note that this
letter did not undergo the requisite public rulemaking process at the
State level, so the EPA does not consider it to be either a SIP
submission itself or a supplement to New Mexico's existing submission.
See CAA section 110(a)(1), (2) (requiring public notice and hearing
requirements before SIP revisions may be submitted to EPA); id CAA
section 110(i) (prohibiting modifications of SIP requirements except as
conducted pursuant to mandated SIP revision procedures); id. CAA
section 110(l) (mandating analysis of all SIP revisions to ensure such
revisions do not interfere with any applicable requirements under the
Act). See also 40 CFR part 51, subpart F (setting forth minimum
procedural requirements for the preparation, adoption, and submittal of
implementation plans, including requirements of public notice and
hearing); id. Appendix V, section 2 (setting forth administrative
completeness criteria for State plan submissions including evidence of
compliance with procedural requirements). However, the letter was
provided to the EPA prior to this proposed document and the EPA has had
time to consider its contents; the EPA in its discretion will provide
its views on the relevance of the information contained in the letter.
In the letter, NMED explains that it believes the emissions
reductions required under certain compliance orders in New Mexico
applicable to several identified facilities will achieve greater
emissions reductions than what would be achieved for New Mexico's EGU
sources if those sources were subject to the Federal Good Neighbor
Plan. NMED asserts that the EPA identified in the Federal Good Neighbor
Plan that the control requirements for EGUs would achieve roughly 30
tons of ozone season NO<INF>X</INF> emissions reductions on an annual
basis through the strategies of SCR and SNCR optimization and upgrade
of combustion control requirements at qualifying EGUs. In the letter,
NMED identified 236 tons of already established annual NO<INF>X</INF>
emissions reductions due to two compliance orders lodged in 2021 that
it claims had not been reflected in the EPA's 2016v3 emissions
platform, and an additional 77 tons of emissions reductions across 3
years from a consent decree with Matador Production Company.\114\
According to NMED, because these reductions are greater than the
reductions that would be achieved under the Federal Good Neighbor Plan,
there is no need to issue a FIP for New Mexico, since these other
measures have already eliminated a greater mass-based quantity of
emissions than the EPA found needed to eliminate significant
contribution.
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\114\ NMED's July 5, 2023 letter, at 1.
---------------------------------------------------------------------------

The Agency acknowledges and applauds the efforts to enforce air
pollution control requirements and the reductions in ozone-precursor
emissions that are claimed to be achieved under these orders. However,
the information in this letter does not lead the EPA to a different
conclusion with respect to the approvability of New Mexico's interstate
transport SIP submission. In addition to the fact that the letter is
not a formal SIP submission, the EPA does not believe the information
contained in the letter (even if it were a SIP submission) is
sufficient to allow the EPA to conclude that New Mexico would satisfy
its obligations to eliminate significant contribution either at Step 2
or Step 3. The EPA welcomes the opportunity to further discuss with New
Mexico the content of a futu

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