[Federal Register Volume 87, Number 35 (Tuesday, February 22, 2022)]
[Proposed Rules]
[Pages 9463-9475]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2022-02951]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R03-OAR-2021-0872; EPA-HQ-OAR-2021-0663; FRL-9493-01-R3]


Air Plan Disapproval; Maryland; Interstate Transport of Air 
Pollution for the 2015 8-Hour Ozone National Ambient Air Quality 
Standard

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: Pursuant to the Federal Clean Air Act (CAA or the Act), the 
Environmental Protection Agency (EPA) is proposing to disapprove a 
State Implementation Plan (SIP) submittal from Maryland intended to 
address interstate transport for the 2015 8-hour ozone national ambient 
air quality standard (2015 8-hour ozone NAAQS). The ``good neighbor'' 
or ``interstate transport'' provision requires that each state's SIP 
contain adequate provisions to prohibit emissions from within the state 
from significantly contributing to nonattainment or interfering with 
maintenance of the NAAQS in other states. This requirement is part of 
the broader set of ``infrastructure'' requirements, which are designed 
to ensure that the structural components of

[[Page 9464]]

each state's air quality management program are adequate to meet the 
state's responsibilities under the CAA. This disapproval, if finalized, 
will establish a 2-year deadline for the EPA to promulgate a Federal 
Implementation Plan (FIP) to address the relevant interstate transport 
requirements, unless the EPA approves a subsequent SIP submittal that 
meets these requirements. Disapproval does not start a mandatory 
sanctions clock.

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

ADDRESSES: You may send comments, identified as Docket No. EPA-R03-OAR-
2021-0872, by any of the following methods: Federal eRulemaking Portal 
at https://www.regulations.gov following the online instructions for 
submitting comments or via email to <a href="/cdn-cgi/l/email-protection#44232b36202b2a6a292d2f21042134256a232b32"><span class="__cf_email__" data-cfemail="66010914020908480b0f0d032603160748010910">[email protected]</span></a>. Include Docket 
ID No. EPA-R03-OAR-2021-0872 in the subject line of the message. For 
further submission methods contact the person in the FOR FURTHER 
INFORMATION CONTACT section. Include Docket ID No. EPA-R03-OAR-2021-
0872 in the subject line of the message.
    Instructions: All submissions received must include the Docket ID 
No. for this rulemaking. Comments received may be posted without change 
to https://www.regulations.gov/, including any personal information 
provided. For detailed instructions on sending comments and additional 
information on the rulemaking process, see the ``Public Participation'' 
heading of the SUPPLEMENTARY INFORMATION section of this document. Out 
of an abundance of caution for members of the public and our staff, the 
EPA Docket Center and Reading Room are open to the public by 
appointment only to reduce the risk of transmitting COVID-19. Our 
Docket Center staff also continues to provide remote customer service 
via email, phone, and webform. For further information on EPA Docket 
Center services and the current status, please visit us online at 
https://www.epa.gov/dockets.

FOR FURTHER INFORMATION CONTACT: Michael Gordon, Planning & 
Implementation Branch (3AD30), Air & Radiation Division, U.S. 
Environmental Protection Agency, Region III, 1650 Arch Street, 
Philadelphia, Pennsylvania 19103. The telephone number is (215) 814-
2039. Mr. Gordon can also be reached via electronic mail at 
<a href="/cdn-cgi/l/email-protection#2f48405d4b4041014246444a6f4a5f4e01484059"><span class="__cf_email__" data-cfemail="c7a0a8b5a3a8a9e9aaaeaca287a2b7a6e9a0a8b1">[email protected]</span></a>.

SUPPLEMENTARY INFORMATION:
    Public Participation: Submit your comments, identified by Docket ID 
No. EPA-R03-OAR-2021-0872, at https://www.regulations.gov (our 
preferred method), or the other method identified in the ADDRESSES 
section. Once submitted, comments cannot be edited or removed from the 
docket. The EPA may publish any comment received to its public docket. 
Do not submit to EPA's docket at https://www.regulations.gov any 
information you consider to be Confidential Business Information (CBI) 
or other information whose disclosure is restricted by statute. 
Multimedia submissions (audio, video, etc.) must be accompanied by a 
written comment. The written comment is considered the official comment 
and should include discussion of all points you wish to make. The EPA 
will generally not consider comments or comment contents located 
outside of the primary submission (i.e., on the web, cloud, or other 
file sharing system).
    There are two dockets supporting this action, EPA-R03-OAR-2021-0872 
and EPA-HQ-OAR-2021-0663. Docket No. EPA-R03-OAR-2021-0872 contains 
information specific to Maryland, including the notice of proposed 
rulemaking. Docket No. EPA-HQ-OAR-2021-0663 contains additional 
modeling files, emissions inventory files, technical support documents, 
and other relevant supporting documentation regarding interstate 
transport of emissions for the 2015 8-hour ozone NAAQS which are being 
used to support this action. All comments regarding information in 
either of these dockets are to be made in Docket No. EPA-R03-OAR-2021-
0872 only. For additional submission methods, please contact Mike 
Gordon, 215-814-2039, <a href="/cdn-cgi/l/email-protection#8ee9e1fceae1e0a0e3e7e5ebceebfeefa0e9e1f8"><span class="__cf_email__" data-cfemail="c2a5adb0a6adacecafaba9a782a7b2a3eca5adb4">[email protected]</span></a>. For the full EPA public 
comment policy, information about CBI or multimedia submissions, and 
general guidance on making effective comments, please visit https://www.epa.gov/dockets/commenting-epa-dockets. Due to public health 
concerns related to COVID-19, the EPA Docket Center and Reading Room 
are open to the public by appointment only. Our Docket Center staff 
also continues to provide remote customer service via email, phone, and 
webform. For further information and updates on EPA Docket Center 
services, please visit us online at https://www.epa.gov/dockets.
    The EPA continues to carefully and continuously monitor information 
from the Centers for Disease Control and Prevention (CDC), local area 
health departments, and our Federal partners so that we can respond 
rapidly as conditions change regarding COVID-19.
    The index to the docket for this action, Docket No. EPA-R03-OAR-
2021-0872, is available electronically at www.regulations.gov. While 
all documents in the docket are listed in the index, some information 
may not be publicly available via the online docket due to docket file 
size restrictions, such as certain modeling files, or content (e.g., 
CBI). Please contact the EPA Docket Center Services for further 
information.
    Throughout this document, ``we,'' ``us,'' and ``our'' means the 
EPA.

I. Background

A. Description of Statutory Background

    On October 1, 2015, the EPA promulgated a revision to the ozone 
NAAQS (2015 8-hour ozone NAAQS), lowering the level of both the primary 
and secondary standards to 0.070 parts per million (ppm).\1\ Section 
110(a)(1) of the CAA requires states to submit, within 3 years after 
promulgation of a new or revised NAAQS, SIP submissions meeting the 
applicable requirements of section 110(a)(2).\2\ One of these 
applicable requirements is found in CAA section 110(a)(2)(D)(i)(I), 
otherwise known as the ``interstate transport'' or ``good neighbor'' 
provision, which generally requires SIPs to contain adequate provisions 
to prohibit in-state emissions activities from having certain adverse 
air quality effects on other states due to interstate transport of 
pollution. There are two so-called ``prongs'' within CAA section 
110(a)(2)(D)(i)(I). 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).\3\
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    \1\ National Ambient Air Quality Standards for Ozone, Final 
Rule, 80 FR 65292 (October 26, 2015). Although the level of the 
standard is specified in the units of ppm, ozone concentrations are 
also described in parts per billion (ppb). For example, 0.070 ppm is 
equivalent to 70 ppb.
    \2\ SIP revisions that are intended to meet the applicable 
requirements of section 110(a)(1) and (2) of the CAA are often 
referred to as infrastructure SIPs and the applicable elements under 
section 110(a)(2) are referred to as infrastructure requirements.
    \3\ See North Carolina v. EPA, 531 F.3d 896, 909-11 (D.C. Cir. 
2008).

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[[Page 9465]]

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

    The EPA is using the 4-step interstate transport framework (or 4-
step framework) to evaluate all of the states' SIP submittals 
addressing the interstate transport provision for the 2015 8-hour ozone 
NAAQS. The EPA has addressed the interstate transport requirements of 
CAA section 110(a)(2)(D)(i)(I) with respect to prior ozone NAAQS in 
several regional regulatory actions, including the Cross-State Air 
Pollution Rule (CSAPR), which addressed interstate transport with 
respect to the 1997 ozone NAAQS, as well as the 1997 and 2006 fine 
particulate matter standards,\4\ and the Cross-State Air Pollution Rule 
Update (CSAPR Update) \5\ and the Revised CSAPR Update, both of which 
addressed the 2008 ozone NAAQS.\6\
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    \4\ See Federal Implementation Plans: Interstate Transport of 
Fine Particulate Matter and Ozone and Correction of SIP Approvals, 
76 FR 48208 (August 8, 2011).
    \5\ Cross-State Air Pollution Rule Update for the 2008 Ozone 
NAAQS, 81 FR 74504 (October 26, 2016).
    \6\ In 2019, the D.C. Circuit Court of Appeals remanded the 
CSAPR Update to the extent it failed to require upwind states to 
eliminate their significant contribution by the next applicable 
attainment date by which downwind states must come into compliance 
with the NAAQS, as established under CAA section 181(a). Wisconsin 
v. EPA, 938 F.3d 303, 313 (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).
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    Through the development and implementation of the CSAPR rulemakings 
and prior regional rulemakings pursuant to the interstate transport 
provision,\7\ the EPA, working in partnership with states, developed 
the following 4-step interstate transport framework to evaluate a 
state's obligations to eliminate interstate transport emissions under 
the interstate transport provision for the ozone NAAQS: (1) Identify 
monitoring sites that are projected to have problems attaining and/or 
maintaining the NAAQS (i.e., nonattainment and/or maintenance 
receptors); (2) identify states that impact those air quality problems 
in other (i.e., downwind) states sufficiently such that the states are 
considered ``linked'' and therefore warrant further review and 
analysis; (3) identify the emissions reductions necessary (if any), 
applying a multifactor analysis, to eliminate each linked upwind 
state's significant contribution to nonattainment or interference with 
maintenance of the NAAQS at the locations identified in Step 1; and (4) 
adopt permanent and enforceable measures needed to achieve those 
emissions reductions.
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    \7\ In addition to the 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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C. Background on the EPA's Ozone Transport Modeling Information

    In general, the EPA has performed nationwide air quality modeling 
to project ozone design values which are used in combination with 
measured data to identify nonattainment and maintenance receptors. To 
quantify the contribution of emissions from specific upwind states on 
2023 ozone design values for the identified downwind nonattainment and 
maintenance receptors, the EPA performed nationwide, state-level ozone 
source apportionment modeling for 2023. The source apportionment 
modeling provided contributions to ozone at receptors from precursor 
emissions of anthropogenic nitrogen oxides (NO<INF>X</INF>) and 
volatile organic compounds (VOCs) in individual upwind states.
    The EPA has released several documents containing projected ozone 
design values, contributions, and information relevant to evaluating 
interstate transport with respect to the 2015 8-hour ozone NAAQS. 
First, on January 6, 2017, the EPA published a notice of data 
availability (NODA) in which the EPA requested comment on preliminary 
interstate ozone transport data, including projected ozone design 
values and interstate contributions for 2023 using a 2011 emissions 
platform.\8\ In the NODA, the EPA used the year 2023 as the analytic 
year for this preliminary modeling because that year aligns with the 
expected attainment year for Moderate ozone nonattainment areas for the 
2015 8-hour ozone NAAQS.\9\ On October 27, 2017, the EPA released a 
memorandum (October 2017 memorandum) containing updated modeling data 
for 2023, which incorporated changes made in response to comments on 
the NODA and noted that the modeling may be useful for states 
developing SIPs to address interstate transport obligations for the 
2008 ozone NAAQS.\10\ 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 8-hour ozone NAAQS at Step 1 of the 4-step interstate transport 
framework.\11\ 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.\12\ The EPA subsequently issued two more memoranda 
in August and October 2018, providing additional information to states 
developing interstate transport SIP submissions for the 2015 8-hour 
ozone NAAQS concerning, respectively, potential contribution thresholds 
that may be appropriate to apply in Step 2 of the 4-step interstate 
transport framework, and considerations for identifying downwind areas 
that may have problems maintaining the standard at Step 1 of the 4-step 
interstate transport framework.\13\
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    \8\ 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).
    \9\ See 82 FR 1733, 1735 (January 6, 2017).
    \10\ 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.
    \11\ 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.
    \12\ 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.''
    \13\ 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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    Since the release of the modeling data shared in the March 2018 
memorandum, the EPA performed updated modeling using a 2016 emissions 
platform (i.e., 2016v1). This emissions platform was developed under 
the EPA/Multi-Jurisdictional Organization (MJO)/state collaborative 
project.\14\ This collaborative project was a multi-year joint effort 
by the EPA, MJOs, and states to develop a new, more

[[Page 9466]]

recent emissions platform for use by the EPA and states in regulatory 
modeling as an improvement over the dated 2011 emissions platform 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.\15\ Although the Revised CSPAR 
Update addressed transport for the 2008 ozone NAAQS, the projected 
design values and contributions from the 2016v1 emissions platform are 
also useful for identifying downwind ozone problems and linkages with 
respect to the 2015 8-hour ozone NAAQS.\16\
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    \14\ The results of this modeling, as well as the underlying 
modeling files, are included in docket ID No. EPA-HQ-OAR-2021-0663.
    \15\ See 85 FR 68964, 68981.
    \16\ 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 2016v1 emissions platform to include mobile emissions 
from the EPA's Motor Vehicle Emission Simulator MOVES3 model \17\ and 
updated emissions projections for electric generating units (EGUs) that 
reflect the emissions reductions from the Revised CSAPR Update, recent 
information on plant closures, and other sector trends. The construct 
of the updated emissions platform, 2016v2 (2016v2 emissions platform), 
is described in the Emissions Modeling technical support document (TSD) 
for this proposed rulemaking.\18\ The EPA performed air quality 
modeling of the 2016v2 emissions platform using the most recent public 
release version of the Comprehensive Air-quality Model with extensions 
(CAMx) photochemical modeling, version 7.10 \19\ in evaluating these 
submissions with respect to Steps 1 and 2 of the 4-step interstate 
transport framework and generally referenced within this action as 
2016v2 modeling for 2023. By using the updated modeling results, the 
EPA is using the most recent available and technically appropriate 
information for this proposed rulemaking. Section III of this document 
and the Air Quality Modeling TSD for the 2015 8-hour Ozone NAAQS 
Transport SIP Proposed Actions, included in Docket ID No. EPA-HQ-OAR-
2021-0663 for this proposal, contain additional detail on the EPA's 
2016v2 modeling. In this document, the EPA is accepting public comment 
on this updated 2023 modeling, which uses the 2016v2 emissions 
platform. Comments on the EPA's air quality modeling should only be 
submitted in the Regional docket for this action, docket ID No. EPA-
R03-OAR-2021-0872. No comments on any topic are being accepted in 
docket ID No. EPA-HQ-OAR-2021-0663.
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    \17\ Additional details and documentation related to the MOVES3 
model can be found at https://www.epa.gov/moves/latest-version-motor-vehicle-emission-simulator-moves.
    \18\ See Technical Support Document (TSD) Preparation of 
Emissions Inventories for the 2016v2 North American Emissions 
Modeling Platform included in the Headquarters docket ID No. EPA-HQ-
OAR-2021-0663.
    \19\ Ramboll Environment and Health, January 2021, www.camx.com.
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    States may have chosen to rely on the results of the EPA modeling 
and/or alternative modeling performed by states or MJOs to evaluate 
downwind air quality problems and contributions as part of their 
submissions. In Section III of this document, the EPA evaluates how 
Maryland used air quality modeling information in their submission.

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

    The EPA proposes to apply a consistent set of policy judgments 
across all states for purposes of evaluating interstate transport 
obligations and the approvability of interstate transport SIP 
submittals for the 2015 8-hour ozone NAAQS. These policy judgments 
reflect consistency with relevant case law and past agency practice as 
reflected in the CSAPR and related rulemakings. Nationwide consistency 
in approach is particularly important in the context of interstate 
ozone transport, which is a regional-scale pollution problem involving 
many smaller contributors. Effective policy solutions to the problem of 
interstate ozone transport going back to the NO<INF>X</INF> SIP Call 
have necessitated the application of a uniform framework of policy 
judgments in order to ensure an ``efficient and equitable'' approach. 
See EME Homer City Generation, LP v. EPA, 572 U.S. 489, 519 (2014).
    In the March, August, and October 2018 memoranda, the EPA 
recognized that states may be able to establish alternative approaches 
to addressing their interstate transport obligations for the 2015 8-
hour ozone NAAQS that vary from a nationally uniform framework. The EPA 
emphasized in these memoranda, however, that such alternative 
approaches must be technically justified and appropriate in light of 
the facts and circumstances of each particular state's submittal. In 
general, the EPA continues to believe that deviation from a nationally 
consistent approach to ozone transport must be substantially justified 
and have a well-documented technical basis that is consistent with 
relevant case law. Where states submitted SIPs that rely on any such 
potential ``flexibilities'' as may have been identified or suggested in 
the past, the EPA will evaluate whether the state adequately justified 
the technical and legal basis for doing so. The EPA's proposed 
framework with respect to analytic year, definition of nonattainment 
and maintenance receptors, selection of contribution threshold, and 
multifactor control strategy assessment is described in this section.
    The EPA notes that certain concepts included in an attachment to 
the March 2018 memorandum require unique consideration, and these ideas 
do not constitute agency guidance with respect to transport obligations 
for the 2015 8-hour ozone NAAQS. Attachment A to the March 2018 
memorandum identified a ``Preliminary List of Potential Flexibilities'' 
that could potentially inform SIP development.\20\ However, the EPA 
made clear in Attachment A that the list of ideas were not suggestions 
endorsed by the Agency but rather ``comments provided in various 
forums'' on which the EPA sought ``feedback from interested 
stakeholders.'' \21\ 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 is the EPA 
specifically recommending that states use these approaches.'' \22\ 
Attachment A to the March 2018 memorandum, therefore, does not 
constitute agency guidance, but was intended to generate further 
discussion around potential approaches to addressing ozone transport 
among interested stakeholders. To the extent states sought to develop 
or rely on these ideas in support of their SIP submittals, the EPA will 
thoroughly review the technical and legal justifications for doing so.
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    \20\ March 2018 memorandum, Attachment A.
    \21\ Id. at A-1.
    \22\ Id.
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    The remainder of this section describes the EPA's proposed 
framework with respect to analytic year, definition of nonattainment 
and maintenance receptors, selection of contribution threshold, and 
multifactor control strategy assessment.
1. Selection of Analytic Year
    In general, the states and the EPA must implement the interstate 
transport provision in a manner ``consistent with the provisions of 
[title I of the CAA.]'' CAA section 110(a)(2)(D)(i). This requires, 
among other things, that these

[[Page 9467]]

obligations are addressed consistently with the timeframes for downwind 
areas to meet their CAA obligations. With respect to ozone NAAQS, under 
CAA section 181(a), this means obligations must be addressed ``as 
expeditiously as practicable'' and no later than the schedule of 
attainment dates provided in CAA section 181(a)(1).\23\ Several D.C. 
Circuit court decisions address the issue of the relevant analytic year 
for the purposes of evaluating ozone transport air-quality problems. On 
September 13, 2019, the D.C. Circuit issued a decision in Wisconsin v. 
EPA, remanding the CSAPR Update to the extent that it failed to require 
upwind states to eliminate their significant contribution by the next 
applicable attainment date by which downwind states must come into 
compliance with the NAAQS, as established under CAA section 181(a). 938 
F.3d 303 at 313.
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    \23\ For attainment dates for the 2015 8-hour ozone NAAQS, refer 
to CAA section 181(a), 40 CFR 51.1303, and Additional Air Quality 
Designations for the 2015 Ozone National Ambient Air Quality 
Standards, 83 FR 25776 (June 4, 2018, effective August 3, 2018).
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    On May 19, 2020, the D.C. Circuit issued a decision in Maryland v. 
EPA that cited the Wisconsin decision in holding that the EPA must 
assess the impact of interstate transport on air quality at the next 
downwind attainment date, including Marginal area attainment dates, in 
evaluating the basis for the EPA's denial of a petition under CAA 
section 126(b). Maryland v. EPA, 958 F.3d 1185, 1203-04 (D.C. Cir. 
2020). The court noted that ``section 126(b) incorporates the Good 
Neighbor Provision,'' and, therefore, ``EPA must find a violation [of 
section 126] if an upwind source will significantly contribute to 
downwind nonattainment at the next downwind attainment deadline. 
Therefore, the agency must evaluate downwind air quality at that 
deadline, not at some later date.'' Id. at 1204 (emphasis added). The 
EPA interprets the court's holding in Maryland as requiring the states 
and the Agency, under the good neighbor provision, to assess downwind 
air quality as expeditiously as practicable and no later than the next 
applicable attainment date,\24\ which is now the Moderate area 
attainment date under CAA section 181 for ozone nonattainment. The 
Moderate area attainment date for the 2015 8-hour ozone NAAQS is August 
3, 2024.\25\ The EPA believes that 2023 is now the appropriate year for 
analysis of interstate transport obligations for the 2015 8-hour ozone 
NAAQS, because the 2023 ozone season is the last relevant ozone season 
during which achieved emissions reductions in linked upwind states 
could assist downwind states with meeting the August 3, 2024 Moderate 
area attainment date for the 2015 8-hour ozone NAAQS.
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    \24\ The EPA notes that the court in Maryland did not have 
occasion to evaluate circumstances in which the EPA may determine 
that an upwind linkage to a downwind air quality problem exists at 
Steps 1 and 2 of the interstate transport framework by a particular 
attainment date, but for reasons of impossibility or profound 
uncertainty the Agency is unable to mandate upwind pollution 
controls by that date. See Wisconsin, 938 F.3d at 320. The D.C. 
Circuit noted in Wisconsin that upon a sufficient showing, these 
circumstances may warrant flexibility in effectuating the purpose of 
the interstate transport provision.
    \25\ See CAA section 181(a); 40 CFR 51.1303; Additional Air 
Quality Designations for the 2015 Ozone National Ambient Air Quality 
Standards, 83 FR 25776 (June 4, 2018, effective August 3, 2018).
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    The EPA recognizes that the attainment date for nonattainment areas 
classified as Marginal for the 2015 8-hour ozone NAAQS was August 3, 
2021. Under the Maryland holding, any necessary emissions reductions to 
satisfy interstate transport obligations should have been implemented 
by no later than this date. At the time of the statutory deadline to 
submit interstate transport SIPs (October 1, 2018), many states relied 
upon the EPA modeling of the year 2023, and no state provided an 
alternative analysis using a 2021 analytic year (or the prior 2020 
ozone season). However, the EPA must act on SIP submittals using the 
information available at the time it takes such action. In this 
circumstance, the EPA does not believe it would be appropriate to 
evaluate states' obligations under CAA section 110(a)(2)(D)(i)(I) as of 
an attainment date that is wholly in the past, because the Agency 
interprets the interstate transport provision as forward looking. See 
86 FR at 23074; see also Wisconsin, 938 F.3d at 322. Consequently, in 
this proposal the EPA will use the analytical year of 2023 to evaluate 
each state's CAA section 110(a)(2)(D)(i)(I) SIP submission with respect 
to the 2015 8-hour ozone NAAQS.
2. Step 1 of the 4-Step Interstate Transport Framework
    In Step 1, the EPA identifies monitoring sites that are projected 
to have problems attaining and/or maintaining the NAAQS in the 2023 
analytic year. Where the EPA's analysis shows that a site does not fall 
under the definition of a nonattainment or maintenance receptor, that 
site is excluded from further analysis under the EPA's 4-step 
interstate transport framework. For sites that are identified as a 
nonattainment or maintenance receptor in 2023, the EPA proceeds to the 
next step of our 4-step interstate transport framework by identifying 
the upwind state's contribution to those receptors.
    The EPA's approach to identifying ozone nonattainment and 
maintenance receptors in this action is consistent with the approach 
used in previous transport rulemakings. The EPA's approach gives 
independent consideration to both the ``contribute significantly to 
nonattainment'' and the ``interfere with maintenance'' prongs of CAA 
section 110(a)(2)(D)(i)(I), consistent with the D.C. Circuit's 
direction in North Carolina v. EPA.\26\
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    \26\ See North Carolina v. EPA, 531 F.3d at 910-11 (holding that 
the EPA must give ``independent significance'' to each prong of CAA 
section 110(a)(2)(D)(i)(I)).
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    For the purpose of this proposal, the EPA identifies nonattainment 
receptors as those monitoring sites that are projected to have average 
design values that exceed the NAAQS and that are also measuring 
nonattainment based on the most recent monitored design values. This 
approach is consistent with prior transport rulemakings, such as the 
CSAPR Update, where the EPA defined nonattainment receptors as those 
areas that both currently measure nonattainment and that the EPA 
projects will be in nonattainment in the future analytic year (i.e., 
2023).\27\
---------------------------------------------------------------------------

    \27\ 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).
---------------------------------------------------------------------------

    In addition, in this proposal, the EPA identifies a receptor to be 
a ``maintenance'' receptor for purposes of defining interference with 
maintenance, consistent with the method used in the CSAPR and upheld by 
the D.C. Circuit in EME Homer City Generation, L.P. v. EPA, 795 F.3d 
118, 136 (D.C. Cir. 2015).\28\ 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

[[Page 9468]]

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, 
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.
---------------------------------------------------------------------------

    \28\ See 76 FR 48208 (August 8, 2011). CSAPR Update and Revised 
CSAPR Update also used this approach. See 81 FR 74504 (October 26, 
2016) and 86 FR 23054 (April 30, 2021).
---------------------------------------------------------------------------

    Recognizing that nonattainment receptors are also, by definition, 
maintenance receptors, the EPA often uses the term ``maintenance-only'' 
to refer to those receptors that are not nonattainment receptors. 
Consistent with the concepts for maintenance receptors, as described 
above, the EPA identifies ``maintenance-only'' receptors as those 
monitoring sites that have projected average design values above the 
level of the applicable NAAQS, but that are not currently measuring 
nonattainment based on the most recent official design values. In 
addition, those monitoring sites with projected average design values 
below the NAAQS, but with projected maximum design values above the 
NAAQS are also identified as ``maintenance only'' receptors, even if 
they are currently measuring nonattainment based on the most recent 
official design values.
3. Step 2 of the 4-Step Interstate Transport Framework
    In Step 2, the EPA quantifies the contribution of each upwind state 
to each receptor in the 2023 analytic year. The contribution metric 
used in Step 2 is defined as the average impact from each state to each 
receptor on the days with the highest ozone concentrations at the 
receptor based on the 2023 modeling. If a state's contribution value 
does not equal or exceed the threshold of 1 percent of the NAAQS (i.e., 
0.70 parts per billion (ppb) for the 2015 8-hour ozone NAAQS), the 
upwind state is not ``linked'' to a downwind air quality problem, and 
the EPA, therefore, concludes that the state does not significantly 
contribute to nonattainment or interfere with maintenance of the NAAQS 
in the downwind states. However, if a state's contribution equals or 
exceeds the 1 percent threshold, the state's emissions are further 
evaluated in Step 3, considering both air quality and cost as part of a 
multi-factor analysis, to determine what, if any, emissions might be 
deemed ``significant'' and, thus, must be eliminated under CAA section 
110(a)(2)(D)(i)(I). The EPA is proposing to rely in the first instance 
on the 1 percent threshold for the purpose of evaluating a state's 
contribution to nonattainment or maintenance of the 2015 8-hour ozone 
NAAQS (i.e., 0.70 ppb) at downwind receptors. This is consistent with 
the Step 2 approach that the EPA applied in CSAPR for the 1997 ozone 
NAAQS, which has subsequently been applied in the CSAPR Update when 
evaluating interstate transport obligations for the 2008 ozone NAAQS. 
The EPA continues to find 1 percent to be an appropriate threshold. For 
ozone, as the EPA found in the Clean Air Interstate Rule (CAIR), CSAPR, 
and CSAPR Update, a portion of the nonattainment problems from 
anthropogenic sources in the U.S. result from the combined impact of 
contributions from many upwind states, along with contributions from 
in-state sources and, in some cases, substantially larger contributions 
from a subset of particular upwind states. The EPA's analysis shows 
that much of the ozone transport problem being analyzed in this 
proposed rulemaking is still the result of the collective impacts of 
contributions from many upwind states. Therefore, application of a 
consistent contribution threshold is necessary to identify those upwind 
states that should have responsibility for addressing their 
contribution to the downwind nonattainment and maintenance problems to 
which they collectively contribute. Continuing to use 1 percent of the 
NAAQS as the screening metric to evaluate collective contribution from 
many upwind states also allows the EPA (and states) to apply a 
consistent framework to evaluate interstate emissions transport under 
the interstate transport provision from one NAAQS to the next. See 81 
FR at 74518. See also 86 FR at 23085 (reviewing and explaining 
rationale from CSAPR, 76 FR at 48237-38, for selection of 1 percent 
threshold).
    The EPA's August 2018 memorandum recognized that in certain 
circumstances, a state may be able to establish that an alternative 
contribution threshold of 1 ppb is justifiable. Where a state relies on 
this alternative threshold, and where that state determined that it was 
not linked at Step 2 using the alternative threshold, the EPA will 
evaluate whether the state provided a technically sound assessment of 
the appropriateness of using this alternative threshold based on the 
facts and circumstances underlying its application in the particular 
SIP submission.
4. Step 3 of the 4-Step Interstate Transport Framework
    Consistent with the EPA's longstanding approach to eliminating 
significant contribution or interference with maintenance, at Step 3, 
states linked at Steps 1 and 2 are generally expected to prepare a 
multifactor assessment of potential emissions controls. The EPA's 
analysis at Step 3 in prior Federal actions addressing interstate 
transport requirements has primarily focused on an evaluation of cost-
effectiveness of potential emissions controls (on a marginal cost-per-
ton basis), the total emissions reductions that may be achieved by 
requiring such controls (if applied across all linked upwind states), 
and an evaluation of the air quality impacts such emissions reductions 
would have on the downwind receptors to which a state is linked; other 
factors may potentially be relevant if adequately supported. In 
general, where the EPA's or alternative air quality and contribution 
modeling establishes that a state is linked at Steps 1 and 2, it will 
be insufficient at Step 3 for a state merely to point to its existing 
rules requiring control measures as a basis for approval. In general, 
the emissions-reducing effects of all existing emissions control 
requirements are already reflected in the air quality results of the 
modeling for Steps 1 and 2. If the state is shown to still be linked to 
one or more downwind receptor(s), states must provide a well-documented 
evaluation determining whether their emissions constitute significant 
contribution or interference with maintenance by evaluating additional 
available control opportunities by preparing a multifactor assessment. 
While the EPA has not prescribed a particular method for this 
assessment, the EPA expects states at a minimum to present a sufficient 
technical evaluation. This would typically include information on 
emissions sources, applicable control technologies, emissions 
reductions, costs, cost effectiveness, and downwind air quality impacts 
of the estimated reductions, before concluding that no additional 
emissions controls should be required.\29\
---------------------------------------------------------------------------

    \29\ As examples of general approaches for how such an analysis 
could be conducted for their sources, states could look to the CSAPR 
Update, 81 FR 74504, 74539-51 (October 26, 2016); CSAPR, 76 FR 
48208, 48246-63 (August 8, 2011); CAIR, 70 FR 25162, 25195-229 (May 
12, 2005); or the NO<INF>X</INF> SIP Call, 63 FR 57356, 57399-405 
(October 27, 1998). See also Revised CSAPR Update, 86 FR 23054, 
23086-23116 (April 30, 2021). 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.

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

[[Page 9469]]

5. Step 4 of the 4-Step Interstate Transport Framework
    At Step 4, states (or the EPA) develop permanent and federally 
enforceable control strategies to achieve the emissions reductions 
determined to be necessary at Step 3 to eliminate significant 
contribution to nonattainment or interference with maintenance of the 
NAAQS. For a state linked at Steps 1 and 2 to rely on an emissions 
control measure at Step 3 to address its interstate transport 
obligations, that measure must be included in the state's SIP so that 
it is permanent and federally enforceable. See CAA section 110(a)(2)(D) 
(``Each such [SIP] shall . . . contain adequate provisions . . .''). 
See also CAA 110(a)(2)(A); Committee for a Better Arvin v. U.S. E.P.A., 
786 F.3d 1169, 1175-76 (9th Cir. 2015) (holding that measures relied on 
by state to meet CAA requirements must be included in the SIP).

II. Maryland's SIP Submission Addressing Interstate Transport of Air 
Pollution for the 2015 8-Hour Ozone NAAQS

    On October 11, 2018, the Maryland Department of the Environment 
(MDE), on behalf of the State of Maryland, made a SIP submission to 
address most of the 2015 8-hour ozone NAAQS i-SIP requirements under 
CAA section 110(a)(2), except for the CAA section 110(a)(2)(D)(i)(I) 
(the ``Good Neighbor'' or ``interstate transport'') requirements, which 
Maryland proposed to address in a separate SIP submittal. The EPA 
published a final approval of this SIP submission on September 18, 
2019, 84 FR 49062. On October 16, 2019, MDE then submitted a separate, 
supplemental SIP revision addressing only the CAA section 
110(a)(2)(D)(i)(I) interstate transport requirements for the 2015 8-
hour ozone NAAQS (the 2019 SIP).\30\ Maryland's 2019 SIP submittal 
provided an analysis of ozone monitoring data and emission trends, as 
well as a list of already-enacted Federal and State air pollution 
control measures, before concluding that Maryland satisfied its section 
110(a)(2)(D)(i)(I) Good Neighbor obligations for purposes of the 2015 
8-hour ozone NAAQS.
---------------------------------------------------------------------------

    \30\ See the October 16, 2019 SIP submittal included in docket 
ID No. EPA-R03-OAR-2021-0872.
---------------------------------------------------------------------------

    Maryland's SIP submittal roughly followed the 4-step interstate 
transport framework recommended by the EPA. For Steps 1 and 2, Maryland 
relied on the EPA's modeling in the March 2018 memorandum to 
demonstrate that it complies with the requirements of CAA section 
110(a)(2)(D)(i)(I) for the 2015 8-hour ozone NAAQS. As part of Step 1, 
Maryland's SIP submittal identified the downwind nonattainment and 
maintenance receptors for which the EPA's modeling projected impacts 
from Maryland emissions, and thus linkage in 2023. The State examined 
historical ozone design values based on past monitoring data from 2015 
to 2018 at key linked monitors to evaluate the likelihood of future 
compliance with the NAAQS at those locations. As part of Step 2, 
Maryland's SIP submission specified that even though the EPA's August 
31, 2018 \31\ memorandum concluded that it may be reasonable and 
appropriate for states to use a 1 ppb contribution threshold, as an 
alternative to a 1-percent threshold, Maryland chose to use the one-
percent threshold as it captured a greater contribution from upwind 
states.
---------------------------------------------------------------------------

    \31\ Analysis of Contribution Thresholds Memo, August 2018, 
https://www.epa.gov/sites/production/files/2018-09/documents/contrib_thresholds_transport_sip_subm_2015_ozone_memo_08_31_18.pdf.
---------------------------------------------------------------------------

    In the 2019 SIP submittal, Maryland also asserted that it does not 
agree with the results of the EPA's 2023 projection modeling outlined 
in the March 2018 memorandum, because in their opinion the air quality 
modeling accompanying the March 2018 memorandum was ``based on flawed, 
unenforceable inventory assumptions and modeling methodology'' that 
resulted in lower projected 2023 design values and state contributions 
that differ from the expected reality.\32\ Maryland further explained 
that even though that was the most current modeling available at the 
time, states should not solely rely on it to fulfill their interstate 
transport obligations, and for that reason, the State identified four 
items that, in its opinion, need to be included in a SIP submission to 
address section 110(a)(2)(D)(i)(I) for the EPA to approve it. These 
four items include the following: (i) Completion of the entire 4-step 
interstate transport framework; (ii) requiring optimization of post-
combustion controls at EGUs as a cost-effective strategy for NOx 
reduction; (iii) requiring that reductions included in the modeling for 
interstate transport SIP submittals be permanent, enforceable and 
implemented as expeditiously as possible; and (iv) requiring that the 
optimization of post-combustion controls at EGUs happen on a daily 
basis, consistent with the way peak days are used to demonstrate 
attainment with the standards using measured ozone data. Even though 
Maryland did not agree with the results of the EPA's March 2018 
memorandum modeling on the basis that it contains unenforceable control 
measures, the State did use that modeling analysis to fulfill Step 2 of 
the 4-step interstate transport framework.
---------------------------------------------------------------------------

    \32\ See the October 16, 2019 SIP submittal at 2 included in 
docket ID No. EPA-R03-OAR-2021-0872.
---------------------------------------------------------------------------

    For Step 3 of the 4-step interstate transport framework, Maryland's 
SIP submittal highlighted the EPA's CSAPR Update rule. In particular, 
the State focused on the determination of the necessary level of 
NO<INF>X</INF> emission control and the state budgets for 
NO<INF>X</INF> emissions for EGUs, corresponding to emission levels 
after accounting for operation of existing pollution controls, emission 
reductions available at a certain cost threshold, and any additional 
reductions required to address interstate ozone transport. Maryland 
acknowledged that the CSAPR Update rule aids in the reduction of 
interstate transport through the implementation of NO<INF>X</INF> 
emissions limits for EGUs in 22 eastern states, including Maryland, 
during the ozone season.
    Lastly, with regard to Step 4 of the 4-step interstate transport 
framework, the State's SIP submittal described why it believed that 
Maryland's NO<INF>X</INF> Rule met and exceeded the CSAPR Update 
requirements. Maryland claims that Maryland's NO<INF>X</INF> Rule 
controls EGU NO<INF>X</INF> emissions at levels more stringent than 
required by the CSAPR Update rule. The submittal notes that Maryland 
has implemented its NO<INF>X</INF> Rule in two phases, with Phase 1 
satisfying the CSAPR Update requirements, while Phase 2, which took 
effect in 2020, could be considered as additional emission reductions 
eliminating Maryland's significant contributions to downwind states. As 
part of Step 4, Maryland's submittal also provided a list of state 
regulations and voluntary control measures for a variety of other 
source categories for both NO<INF>X</INF> and VOC emissions that the 
State has adopted to demonstrate how Maryland complies and will 
continue to comply with the good neighbor provisions of the 2015 8-hour 
ozone NAAQS.

III. EPA Evaluation

    The EPA is proposing to find that Maryland's October 16, 2019 SIP 
submission does not meet the state's obligations with respect to 
prohibiting

[[Page 9470]]

emissions that contribute significantly to nonattainment or interfere 
with maintenance of the 2015 8-hour ozone NAAQS in any other state, and 
the EPA is therefore proposing to disapprove Maryland's SIP submission. 
This proposed disapproval is based on newer, updated modeling performed 
by the EPA which was not available when Maryland submitted its 
supplemental SIP, and the EPA's evaluation of the SIP submission using 
the 4-step interstate transport framework.

A. Maryland

1. Evaluation of Information Provided by Maryland Regarding Steps 1 and 
2
    As noted in Section II of this document, at Steps 1 and 2 of the 4-
step interstate transport framework, Maryland used the EPA modeling 
released in the March 2018 memorandum \33\ to identify nonattainment 
and maintenance receptors in 2023 and to determine whether the State 
was linked to any of these receptors in 2023. The March 2018 memorandum 
modeling was the latest modeling available when Maryland submitted its 
SIP revision in October 2019. As described previously in this document, 
the EPA has since released air quality modeling using the most recent 
available and technically appropriate emissions data (i.e., 2016v2 
emissions platform). Therefore, the EPA proposes to primarily rely on 
the EPA's most recent modeling to identify nonattainment and 
maintenance receptors and identify upwind state linkages to these 
receptors 2023.
---------------------------------------------------------------------------

    \33\ Page 2 of Maryland's 2019 SIP submission notes that 
Maryland does not agree with the 2023 modeling assessment included 
with the March 2018 memorandum because it is ``based on flawed, 
unenforceable inventory assumptions and modeling assumptions'' that 
result in lower projected 2023 design values and state contributions 
that differ from reality. However, Maryland does not elaborate 
further on these ``flaws,'' nor does Maryland explain how or why 
these flaws, if corrected, would either change the status of any 
receptor or show that Maryland is not linked to any downwind 
nonattainment or maintenance receptors.
---------------------------------------------------------------------------

    In Maryland's 2019 SIP submission, the State used the modeling in 
the EPA's March 2018 memorandum to identify six downwind monitors to 
which Maryland sources contributed to nonattainment or interfered with 
maintenance. The EPA's air quality modeling for 2023 using the 2016v2 
emissions platform shows nonattainment or interference at five of the 
same six monitors, as shown in Table 1 of this document in the 
following subsection, although in slightly differing amounts. As noted 
in Section II of this document, Maryland objected to the modeling 
attached to the March 2018 memorandum by claiming that it relied on 
outdated information and flawed inventory assumptions that would tend 
to lessen downwind contributions from upwind sources. The EPA's air 
quality modeling using the 2016v2 emissions platform would presumably 
address some of Maryland's concerns regarding the March 2018 memorandum 
modeling. As stated in Section I of this document, the EPA is accepting 
comment on this more recent modeling data used to support this action. 
Regardless, both sets of modeling show that Maryland is linked to 
nonattainment or interfering with maintenance at downwind out-of-state 
monitors, and the State did not provide any alternative modeling 
analysis that showed an alternative set of nonattainment or maintenance 
receptors in 2023, nor did Maryland provide an alternative analysis to 
demonstrate that they were not linked to nonattainment or interfering 
with maintenance at downwind monitors. Therefore, both the EPA and 
Maryland agree that Maryland's sources are contributing to 
nonattainment or interfering with maintenance at downwind monitors.
2. Results of the EPA's Step 1 and Step 2 Modeling and Findings for 
Maryland
    As described in Section I of this document, the EPA performed air 
quality modeling using the 2016v2 emissions platform to project design 
values and contributions for 2023. The EPA examined these data to 
determine if emissions from Maryland sources contribute at or above the 
threshold of 1 percent of the 2015 8-hour ozone NAAQS (0.70 ppb) to any 
downwind nonattainment or maintenance receptor. As shown in Table 1 of 
this document, the data \34\ indicate that in 2023, emissions from 
Maryland contribute greater than 1 percent of the NAAQS to 
nonattainment or maintenance-only receptors in Fairfield County and New 
Haven County, Connecticut; and in Queens County and Suffolk County, New 
York.\35\
---------------------------------------------------------------------------

    \34\ Design values and contributions at individual monitoring 
sites nationwide are provide in the file: 
2016v2_DVs_state_contributions.xlsx which is included in docket ID 
No. EPA-HQ-OAR-2021-0663.
    \35\ 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 Maryland 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.
---------------------------------------------------------------------------

    Therefore, based on the EPA's evaluation of the information 
submitted by Maryland, and based on the EPA's most recent modeling 
results for 2023, the EPA proposes to find that Maryland is linked at 
Steps 1 and 2 and has an obligation to assess potential emissions 
reductions from sources or other emissions activity at Step 3 of the 4-
step framework.

                                     Table 1--Maryland Linkage Results Based on EPA's Updated 2016v2-Based Modeling
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                         2023 average     2023 maximum       Maryland
            Receptor ID                     Location                 Nonattainment/maintenance           design value     design value     contribution
                                                                                                            (ppb)            (ppb)            (ppb)
--------------------------------------------------------------------------------------------------------------------------------------------------------
090013007..........................  Fairfield County--      Nonattainment...........................             74.3             75.2             1.18
                                      Stratford, CT.
090019003..........................  Fairfield County--      Nonattainment...........................             76.9             77.2             1.18
                                      Westfield, CT.
090010017..........................  Fairfield County--      Maintenance.............................             73.4             74.0             0.67
                                      Greenwich, CT.
090099002..........................  New Haven--Madison, CT  Maintenance.............................             71.7             73.8             1.51
360810124..........................  Queens County, NY.....  Maintenance.............................             66.2             67.8             1.10
361030002..........................  Suffolk County--        Nonattainment...........................             67.0             68.8             1.12
                                      Babylon, NY.
--------------------------------------------------------------------------------------------------------------------------------------------------------

3. Evaluation of Information Provided Regarding Step 3
    At Step 3 of the 4-step interstate transport framework, a state's 
emissions are further evaluated, in light of multiple factors, 
including air quality and cost considerations, to determine what, if 
any, emissions significantly contribute to nonattainment or interfere 
with maintenance and, thus, must be eliminated under CAA section 
110(a)(2)(D)(i)(I).

[[Page 9471]]

    To evaluate effectively which emissions in the state should be 
deemed ``significant'' and therefore prohibited, states generally 
should prepare an accounting of sources and other emissions activity 
for relevant pollutants and assess potential, additional emissions 
reduction opportunities and resulting downwind air quality 
improvements. The EPA has consistently applied this general approach 
(i.e., Step 3 of the 4-step interstate transport framework) when 
identifying emissions contributions that the Agency has determined to 
be ``significant'' (or interfere with maintenance) in each of its prior 
Federal, regional ozone transport rulemakings, and this interpretation 
of the statute has been upheld by the Supreme Court. See EME Homer 
City, 572 U.S. 489, 519 (2014). While the EPA has not directed states 
that they must conduct a Step 3 analysis in precisely the manner the 
EPA has done in its prior regional transport rulemakings, state 
implementation plans addressing the obligations in CAA section 
110(a)(2)(D)(i)(I) must prohibit ``any source or other type of 
emissions activity within the State'' from emitting air pollutants 
which will contribute significantly to downwind air quality problems. 
Thus, states must complete something similar to the EPA's analysis (or 
an alternative approach to defining ``significance'' that comports with 
the statute's objectives) to determine whether and to what degree 
emissions from a state should be ``prohibited'' to eliminate emissions 
that will ``contribute significantly to nonattainment in, or interfere 
with maintenance of,'' the NAAQS in any other state. At Step 3 of the 
4-step interstate transport framework, Maryland did not include an 
accounting of all of the NO<INF>X</INF> emitting facilities in the 
state along with an analysis of potential NO<INF>X</INF> emissions 
control technologies, their associated costs, estimated emissions 
reductions, and downwind air quality improvements.
    Maryland's analysis instead focused on the CSAPR Update rule and 
described how, as of May 2017, that rule has reduced ozone season 
NO<INF>X</INF> emissions from power plants in 22 eastern states, 
including Maryland. Maryland referenced the EPA's finding in the CSAPR 
Update that for the updated NO<INF>X</INF> ozone season budgets for 
EGUs, an increased cost threshold of $1,400 per ton of NO<INF>X</INF> 
reduced was appropriate, because it represented the level of maximum 
marginal NO<INF>X</INF> reduction with respect to cost, while not over-
controlling upwind states' emissions. Maryland's SIP submittal included 
a table with the 22 states' updated ozone season NO<INF>X</INF> 
budgets. That table shows that for Maryland, the CSAPR Update 
NO<INF>X</INF> ozone season budget, at the $1,400 per ton threshold, 
was 3,238 tons.\36\
---------------------------------------------------------------------------

    \36\ See Maryland's October 16, 2019 SIP submittal included in 
docket ID No. EPA-R03-OAR-2021-0872.
---------------------------------------------------------------------------

    Maryland's focus on the CSAPR Update (which reflected a stringency 
at the nominal marginal cost threshold of $1400/ton (2011$) for the 
2008 ozone NAAQS) rule to satisfy their obligations for the 2015 8-hour 
ozone NAAQS is unpersuasive. First, the CSAPR Update did not regulate 
non-electric generating units (non-EGU), so Maryland's reliance on only 
the CSAPR Update analysis is incomplete because Maryland did not 
analyze non-EGU sources. See Wisconsin, 938 F.3d at 318-20. Second, 
relying on the CSAPR Update's (or any other CAA program's) 
determination of cost-effectiveness without further Step 3 analysis by 
Maryland is not approvable. Cost-effectiveness must be assessed in the 
context of the specific CAA program; assessing cost-effectiveness in 
the context of ozone transport should reflect a more comprehensive 
evaluation of the nature of the interstate transport problem, the total 
emissions reductions available at several cost thresholds, and the air 
quality impacts of the reductions at downwind receptors. While the EPA 
has not established a benchmark cost-effectiveness value for the 2015 
8-hour ozone NAAQS interstate transport obligations, because the 2015 
8-hour ozone NAAQS is a more stringent and more protective air quality 
standard, it is reasonable to expect control measures or strategies to 
address interstate transport under this NAAQS to reflect higher 
marginal control costs. As such, the marginal cost threshold of $1,400/
ton for the CSAPR Update (which addresses the 2008 ozone NAAQS and is 
in 2011$) is not an appropriate cost threshold and cannot be approved 
as a benchmark to use for interstate transport SIP submissions for the 
2015 8-hour ozone NAAQS. Furthermore, Maryland did not explain how the 
ozone season NO<INF>X</INF> emission budget for Maryland's EGUs set by 
the CSAPR Update, which was intended to address ozone transport 
nonattainment and maintenance issues for the less-stringent 2008 ozone 
NAAQS, eliminates Maryland's significant contribution to the downwind 
nonattainment and maintenance receptors to which Maryland is linked for 
purposes of the more stringent 2015 8-hour ozone NAAQS.
    In addition, the updated 2023 EPA modeling using the 2016v2 
emissions platform captures all existing CSAPR trading programs in the 
baseline, and that modeling confirms that these control programs were 
not sufficient to eliminate Maryland's linkage at Steps 1 and 2 under 
the 2015 8-hour ozone NAAQS. The State was therefore obligated at Step 
3 to assess additional control measures using a multifactor analysis.
    Finally, relying on a FIP at Step 3 is per se not approvable if the 
state has not adopted that program into its SIP and instead continues 
to rely on the FIP. States may not rely on non-SIP measures to meet SIP 
requirements. See CAA section 110(a)(2)(D) (``Each such [SIP] shall . . 
. contain adequate provisions . . .''). See also CAA section 
110(a)(2)(A); Committee for a Better Arvin v. U.S. E.P.A., 786 F.3d 
1169, 1175-76 (9th Cir. 2015) (holding that measures relied on by state 
to meet CAA requirements must be included in the SIP).
    Notwithstanding the above deficiencies, Maryland asserts at Step 3 
of its analysis that ``Maryland's NO<INF>X</INF> Rule controls EGU 
NO<INF>X</INF> emissions at levels more stringent than what is required 
by the CSAPR Update and it will achieve the necessary reductions to 
meet the State's good neighbor obligations under the 2015 8-hour ozone 
NAAQS.'' \37\ Maryland's submittal provided, among other things, a 
description of the Maryland NO<INF>X</INF> Rule to control 
NO<INF>X</INF> emissions from Coal-Fired EGUs, and the following 
description of the NO<INF>X</INF> Rule is taken largely from Maryland's 
submittal.\38\ Maryland's NO<INF>X</INF> Rule took effect in May 2015 
and contains two phases. Phase I, found at COMAR 26.11.38.3, became 
effective on May 1, 2015 and required owners and operators of affected 
EGUs (coal-fired EGUs in Maryland) to comply with several measures 
meant to optimize their emission controls. These measures included: (i) 
The submission of a plan for approval by MDE and the EPA demonstrating 
how the EGU will operate installed pollution control technology and 
combustion controls during the ozone season to minimize emissions 
(COMAR 26.11.38.03A(1)); (ii) beginning May 1, 2015, and during the 
entire ozone season, requiring the owners and operators to operate and 
optimize the use of all installed pollution and combustion controls

[[Page 9472]]

consistent with the technological limitations, manufacturers' 
specifications, good engineering, maintenance practices, and air 
pollution control practices to minimize emissions (COMAR 
26.11.38.03A(2)); (iii) setting an ozone season system-wide 
NO<INF>X</INF> emission rate of 0.15 pounds per million British units 
(lbs/MMBtu) as a 30-day rolling average for affected EGUs (COMAR 
26.11.38.03B(1)); (iv) exempting EGUs that are the only facility in 
Maryland directly or indirectly owned, operated, or controlled by the 
owner, operator, or controller of the facility from the 0.15 lbs/MMBtu 
system-wide emission rate specified in COMAR 26.11.38.03B(1) (COMAR 
26.11.38.03B(3)); and (v) setting a NO<INF>X</INF> emission rate for 
EGUs using fluidized bed combustors of 0.10 lbs/MMBtu as a 24-hour 
block average on an annual basis while exempting these units from 
meeting COMAR 26.11.38.03A, B(1) and (2), and (C) (COMAR 
26.11.38.03D).\39\ Sources subject to Phase I must also continue 
meeting annual NO<INF>X</INF> reductions in COMAR 26.11.27, Maryland's 
Healthy Air Act. Maryland claims that for owners and operators to meet 
the limits set by Maryland's NO<INF>X</INF> Rule, the sources are 
required to run their controls ``continuously.'' \40\
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    \37\ See Maryland's October 16, 2019 SIP submittal at 7 included 
in docket ID No. EPA-R03-OAR-2021-0872.
    \38\ The Maryland NO<INF>X</INF> rule is codified at COMAR 
26.11.38 (Control of NO<INF>X</INF> Emissions from Coal-Fired 
Electric Generating Units).
    \39\ COMAR 28.11.38(D) does not specify that CFBs must meet the 
0.10 lb/MMBtu 24-hour block average rate on an ``annual basis,'' so 
EPA has not been able to verify that this rate applies outside of 
ozone season.
    \40\ See Maryland's October 16, 2019 SIP submittal at 7 included 
in docket ID No. EPA-R03-OAR-2021-0872.
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    In addition, Maryland's 2019 SIP Submission contains a table (Table 
5) \41\ which the State describes as listing ``NO<INF>X</INF> indicator 
rates'' which demonstrate compliance with the optimization requirement 
in COMAR 26.11.38.03A(1). These rates, found in COMAR 26.11.38.05, are 
described as ``Required 24-Hour Block Average Unit Level NO<INF>X</INF> 
Emission Rates.'' The rates can vary from unit to unit at each affected 
source (and at the unit level based on heat input at Brandon Shores 
Unit 2) and between affected sources. These limits range from 0.07 lbs/
MMBtu to 0.34 lbs/MMBtu. The effect of meeting these indicator rates is 
that ``(2) An affected electric generating unit shall not be required 
to submit a unit-specific report consistent with Sec.  A(3) of this 
regulation when the unit emits at levels that are at or below the . . 
.'' rates in the table. COMAR 26.11.38.05A(2). If the affected EGU does 
not meet its prescribed emission rate, it must submit a report to MDE 
for that day explaining the circumstances of the exceedance. COMAR 
26.11.38.05A(3). As specified in COMAR 26.11.38.05A(4), such exceedance 
shall not be a violation if it was caused by certain events and was in 
accordance with the plan submitted under COMAR 26.11.38.03A(1).
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    \41\ Id. at 8.
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    Regarding Phase I of Maryland's NO<INF>X</INF> Rule, the EPA notes 
that the Phase I NO<INF>X</INF> Rule emission reductions took effect in 
2017 and are captured in the EPA's updated 2023 modeling using the 
2016v2 emissions platform, but that emissions modeling still shows that 
Maryland is contributing to nonattainment or interfering with 
maintenance at downwind receptors in other states. The EPA's latest 
projections of the baseline EGU emissions uses the version 6--Summer 
2021 Reference Case of the Integrated Planning Model (IPM). IPM is a 
multi-regional, dynamic, and deterministic linear programming model of 
the U.S. electric power sector. The model provides forecasts of least 
cost capacity expansion, electricity dispatch, and emission control 
strategies, while meeting energy demand, environmental, transmission, 
dispatch, and reliability constraints.
    The IPM version 6--Summer 2021 Reference Case incorporated recent 
updates through the Summer of 2021 to account for updated Federal and 
State environmental regulations for EGUs. This projected base case 
accounts for the effects of the finalized Mercury and Air Toxics 
Standards rule, CSAPR, the CSAPR Update, the Revised CSAPR Update, New 
Source Review settlements, the final effluent limitation guidelines 
(ELG) Rule, the coal combustion residual (CCR) Rule, and other on-the-
books Federal and State rules (including renewable energy tax credit 
extensions from the Consolidated Appropriations Act of 2021) through 
early 2021 impacting SO<INF>2</INF>, NO<INF>X</INF>, directly emitted 
particulate matter, CO<INF>2</INF>, and power plant operations. It also 
includes final actions the EPA has taken to implement the Regional Haze 
Rule and the best available retrofit technology (BART) requirements. 
Further, the IPM Platform version 6 uses demand projections from the 
Energy Information Agency's (EIA) annual energy outlook (AEO) 2020.\42\
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    \42\ Detailed information and documentation of EPA's Base Case, 
including all the underlying assumptions, data sources, architecture 
parameters, and IPM comments form can be found on EPA's website at: 
https://www.epa.gov/airmarkets/epas-power-sector-modeling-platform-v6-using-ipm-summer-2021-reference-case.
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    The IPM version 6--Summer 2021 Reference Case uses the national 
electric energy data system (NEEDS) v6 database as its source for data 
on all existing and planned-committed units. Units are removed from the 
NEEDS inventory only if a high degree of certainty could be assigned to 
future implementation of the announced future closure or 
retirement.\43\ The available retirement-related information was 
reviewed for each unit, and the following rules are applied to remove:
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    \43\ The ``Capacity Dropped'' and the ``Retired Through 2023'' 
worksheets in NEEDS lists all units that are removed from the NEEDS 
v6 inventory--NEEDS v6 Summer 2021 Reference Case. This data can be 
found on EPA's website at: https://www.epa.gov/airmarkets/national-electric-energy-data-system-needs-v6.
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    (i) Units that are listed as retired in the December 2020 EIA Form 
860M;
    (ii) Units that have a planned retirement year prior to June 30, 
2023 in the December 2020 EIA Form 860M;
    (iii) Units that have been cleared by a regional transmission 
operator (RTO) or independent system operator (ISO) to retire before 
2023, or whose RTO/ISO clearance to retire is contingent on actions 
that can be completed before 2023;
    (iv) Units that have committed specifically to retire before 2023 
under Federal or state enforcement actions or regulatory requirements; 
and
    (v) Finally, units for which a retirement announcement can be 
corroborated by other available information. Units required to retire 
pursuant to enforcement actions or state rules on July 1, 2023 or later 
are retained in NEEDS v6.
    Retirements or closures taking place on or after July 1, 2023 are 
captured as constraints on those units in the IPM modeling, and the 
units are retired in future year projections per the terms of the 
related requirements.
    As highlighted in previous rulemakings, the IPM documentation and 
the EPA's Power Sector Modeling website, the EPA's goal is to explain 
and document the use of IPM in a transparent and publicly accessible 
manner, while also providing for concurrent channels for improving the 
model's assumptions and representation by soliciting constructive 
feedback to improve the model. This includes making all inputs and 
assumptions to the model, output files from the model, and IPM feedback 
form publicly available on the EPA's website.
    Phase II \44\ of Maryland's NO<INF>X</INF> Rule took effect on June 
1, 2020 and applies only to owners or operators of EGUs without SCR 
controls, which consists of seven units at four facilities. These EGUs 
were required to choose between four options by June 1, 2020. The

[[Page 9473]]

options include: (i) Installation and operation of an SCR control 
system by June 1, 2020 that can meet a NO<INF>X</INF> emission rate of 
0.09 lbs/MMBtu during the ozone season based on a 30-day rolling 
average; (ii) permanently retiring the unit; (iii) switching fuel 
permanently from coal to natural gas and operating the unit on natural 
gas; or (iv) meeting a system-wide, daily NO<INF>X</INF> tonnage cap of 
21 tons per day for every day of the ozone season or meeting a system-
wide NO<INF>X</INF> emission rate of 0.13 lbs/MMBtu as a 24-hour block 
average. Option 4, if selected by the source, included additional 
measures requiring a series of greater emission reductions beginning in 
May 2016, 2018, and 2020.\45\ If the owner or operator did not select 
option 4, then the allowable 30-day system-wide rolling average 
NO<INF>X</INF> emission rate was set at 0.15 lbs/MMBtu during the ozone 
season. In addition, option 4 included provisions to ensure that the 
reliability of the electrical system is maintained. There are 
additional provisions in the NO<INF>X</INF> Rule which addressed the 
options and limits applicable if a unit or units included in a 
``system'' as of May 1, 2015 were no longer owned, operated or 
controlled by the ``system.''
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    \44\ Phase II is codified at COMAR 26.11.38.04 (Additional NOX 
Emission Control Requirements).
    \45\ Deeper reductions include meeting a 30-day system-wide 
rolling average NO<INF>X</INF> emission rate of 0.13 lbs/MMBtu in 
May 2016, 0.11 lbs/MMBtu in May 2018, and 0.09 lbs/MMBtu in May 2020 
during the ozone season.
---------------------------------------------------------------------------

    For Phase II, the 2019 SIP Submission notes that Chalk Point, 
Dickerson and Morgantown generating stations selected option 4, that 
Brandon Shores and Herbert A. Wagner generating stations chose the 
optimization requirement in COMAR 26.11.38.03A, and that pursuant to a 
May 23, 2018 settlement agreement, C.P. Crane agreed to cease, and has 
ceased, the burning of coal in Units 1 and 2 by no later than June 15, 
2018, and that the coal-fired boilers have been disabled. Maryland 
predicted that the implementation of both the Phase I and II 
requirements would result in ozone season NO<INF>X</INF> emission 
reductions of 2,507 to 2,627 tons from the base year 2011 emissions. 
The SIP submission did not specify the amount of reduction that would 
occur on any specific date, or the amount of reduction attributable to 
any specific element of the NO<INF>X</INF> Rule. As noted earlier, 
these reductions are likely included in the 2016v2 emission platform, 
and that modeling continues to show that Maryland is contributing to 
downwind nonattainment and maintenance receptors for the 2015 8-hour 
ozone NAAQS.
    The SIP submission also listed several control measures, including 
regulation of emissions from the mobile sector, pursuing significant 
regulation of industrial sources, and implementing VOC rules that 
regulate emissions from other source categories that Maryland has 
implemented to address the control of VOC and NO<INF>X</INF> emissions 
from various point, mobile, and area sources. Maryland's submission 
also described additional voluntary or innovative control measures that 
the State has implemented in attainment plan SIP provisions and stated 
that even though they do not rely on any emission reductions projected 
as a result of the implementation of these voluntary programs to 
demonstrate attainment, these strategies assist in the overall clean 
air goals across the State.
    Unfortunately, Maryland failed to provide any analysis as to how 
these many provisions cited in its 2019 SIP Submittal would eliminate 
the significant contribution of Maryland's emission sources to downwind 
nonattainment or maintenance receptors to which Maryland's emissions 
are linked by the EPA's 2016v2 emissions platform. As noted in Section 
D-4 of this proposal, ``[i]n general, where the EPA's or alternative 
air quality and contribution modeling establishes that a state is 
linked at Steps 1 and 2, it will be insufficient at Step 3 for a state 
merely to point to its existing rules requiring control measures as a 
basis for approval. In general, the emissions-reducing effects of all 
existing emissions control requirements are already reflected in the 
air quality results of the modeling for Steps 1 and 2. If the state is 
shown to still be linked to one or more downwind receptor(s), states 
must provide a well-documented evaluation determining whether their 
emissions constitute significant contribution or interference with 
maintenance by evaluating additional available control opportunities by 
preparing a multifactor assessment.'' Maryland provided no such 
multifactor assessment, and instead claims, without any modeling to 
support this claim, that its existing, already adopted control measures 
for EGUs and other sources will keep Maryland from contributing 
significantly to nonattainment or interfere with maintenance at 
downwind receptors to which it is linked. As such, it does not rise to 
the level of a ``well-documented evaluation.''
    Maryland's SIP submittal also included a weight of evidence 
analysis which analyzed various scenarios. These scenarios evaluated 
various iterations of controls, including SCR controls and emission 
limits comparable to those under the 2015 Maryland NO<INF>X</INF> Rule, 
and applied these SCR controls and limits to emissions sources in other 
states (IL, IN, KY, MI, NC, OH, WV, VA, NY and PA). This is the same 
weight of evidence analysis that Maryland included with its transport 
SIP submittal for the 2008 ozone NAAQS. This modeling analysis only 
addressed the impact that installation of these controls and imposition 
of these limits in other states would have on Maryland's monitors. 
There is no analysis in this weight of evidence portion addressing 
Maryland's contribution to downwind receptors. It therefore does not 
change the EPA's evaluation of Maryland's obligations to address its 
own contributions.
    The EPA acknowledges that Maryland's efforts to reduce 
NO<INF>X</INF> emissions from EGUs, and other requirements to reduce 
NO<INF>X</INF> and VOC emissions from other source categories, have 
helped reduce the interstate transport impacts of emissions from 
Maryland's sources on other states' receptors. In addition to 
addressing ambient ozone levels in nonattainment areas in Maryland, 
these state specific requirements should also help reduce the level of 
NO<INF>X</INF> emissions reductions that Maryland needs to obtain in 
order to meet the section 110(a)(2)(D)(i)(I) requirements for the 2015 
8-hour ozone NAAQS.
    Based on the EPA's evaluation of Maryland's SIP submittal at Step 
3, however, the EPA proposes that Maryland was required to analyze 
emissions from the sources and other emissions activity from within the 
state to determine whether its contributions were significant, and 
therefore the EPA proposes to base part of its disapproval on 
Maryland's failure to do so.
4. Evaluation of Information Provided Regarding Step 4
    Step 4 of the 4-step interstate transport framework calls for 
development of permanent and federally enforceable control strategies 
to achieve the emissions reductions determined to be necessary at Step 
3 to eliminate significant contribution to nonattainment or 
interference with maintenance of the NAAQS. Maryland identified a 
number of measures that were either in development or anticipated to 
occur in the future.\46\ As

[[Page 9474]]

discussed in detail in the Step 3 analysis above, Phase II of 
Maryland's NO<INF>X</INF> Rule (COMAR 26.11.38.04) requires coal-fired 
EGUs that have not installed SCR to choose from one of four options by 
June 1, 2020 that should result in NO<INF>X</INF> emission 
reductions.\47\ Another measure is the Regional Greenhouse Gas 
Initiative (RGGI), which Maryland projects will result in Maryland's 
and other participating states' regional CO<INF>2</INF> emission 
budgets declining by 30% by 2030.\48\ However, the State has not 
revised its SIP to include these emission reductions to ensure the 
reductions are permanent and enforceable. As a result, the EPA also 
proposes as an additional ground for disapproval of Maryland's SIP 
submission the fact that the State has not developed permanent and 
enforceable emissions reductions necessary to meet the obligations of 
CAA section 110(a)(2)(d)(i)(I).
---------------------------------------------------------------------------

    \46\ Pointing to anticipated upcoming emission reductions, even 
if they were not included in the analysis at Steps 1 and 2, is not 
sufficient as a Step 3 analysis, for the reasons discussed in 
Section III.A.3 of this document. In this section, the EPA explains 
that to the extent such anticipated reductions are not included in 
the SIP and rendered permanent and enforceable, reliance on such 
anticipated reductions is also insufficient at Step 4.
    \47\ See Maryland's October 16, 2019 SIP submittal at pages 8-9, 
included in docket ID No. EPA-R03-OAR-2021-0872.
    \48\ Id. at 16.
---------------------------------------------------------------------------

5. Conclusion
    Based on the EPA's evaluation of Maryland's SIP submission, the EPA 
is proposing to find that Maryland's October 16, 2019 SIP submission 
does not meet the State's interstate transport obligations, because it 
fails to show that the provisions adopted by Maryland to reduce 
NO<INF>X</INF> and VOC emissions from sources within Maryland will 
reduce emissions to levels that will not contribute significantly to 
nonattainment or interfere with maintenance of the 2015 8-hour ozone 
NAAQS at downwind monitors in other states to which it is linked. 
Maryland's 2019 SIP submission lacks an analysis of the effect that 
Maryland's adopted emission reductions would have on the specific 
downwind monitors which the EPA's March 2018 memorandum modeling 
analysis and 2016v2 emissions platform analysis determined that 
Maryland sources contribute more than 1 percent to nonattainment or 
interference with maintenance. Maryland's SIP submission disputes 
neither the significant contribution from Maryland nor the ``linkages'' 
between Maryland emissions and these downwind nonattainment or 
maintenance monitors. Further, although Maryland objects to the 
modeling assessment included with the EPA's March 2018 Memorandum, it 
does not offer an alternative modeling assessment showing that 
projected reductions in Maryland's emissions, as outlined in its 2019 
SIP submittal, would eliminate the contribution Maryland's emissions 
make to non-attaining or maintenance monitors identified by the EPA's 
2018 memorandum modeling assessment, or to those in the more recent 
2016v2 emissions platform assessment. Maryland's modeling assessment in 
its 2019 SIP submittal merely explores the varying effects that various 
emission reduction strategies in eastern states would have on ozone 
nonattainment in general, rather than the effect Maryland's reductions 
would have on non-attaining or maintenance monitors to which it is 
linked.

IV. Proposed Action

    The EPA is proposing to disapprove Maryland's October 16, 2019 SIP 
submission pertaining to interstate transport of air pollution which 
will significantly contribute to nonattainment or interfere with 
maintenance of the 2015 8-hour ozone NAAQS in other states. Under CAA 
section 110(c)(1), disapproval would establish a 2-year deadline for 
the EPA to promulgate a FIP for Maryland to address the CAA section 
110(a)(2)(D)(i)(I) interstate transport requirements pertaining to 
significant contribution to nonattainment and interference with 
maintenance of the 2015 8-hour ozone NAAQS in other states, unless the 
EPA approves a new Maryland SIP submission that meets these 
requirements. Disapproval does not start a mandatory sanctions clock 
for Maryland.

V. Statutory and Executive Order Reviews

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

    This action is not a ``significant regulatory action'' as defined 
by Executive Order 12866 and was therefore not submitted to the Office 
of Management and Budget for review.

B. Paperwork Reduction Act (PRA)

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

C. Regulatory Flexibility Act (RFA)

    I certify that this action will not have a significant economic 
impact on a substantial number of small entities under the RFA. This 
action merely proposes to disapprove a SIP submission as not meeting 
the CAA.

D. Unfunded Mandates Reform Act (UMRA)

    This action does not contain any unfunded mandate as described in 
UMRA, 2 U.S.C. 1531-1538, and does not significantly or uniquely affect 
small governments. The action imposes no enforceable duty on any state, 
local or tribal governments or the private sector.

E. Executive Order 13132: Federalism

    This action does not have federalism implications. It will not have 
substantial direct effects on the states, on the relationship between 
the national government and the states, or on the distribution of power 
and responsibilities among the various levels of government.

F. Executive Order 13175: Consultation and Coordination With Indian 
Tribal Governments

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

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

    The EPA interprets Executive Order 13045 as applying only to those 
regulatory actions that concern environmental health or safety risks 
that the EPA has reason to believe may disproportionately affect 
children, per the definition of ``covered regulatory action'' in 
section 2-202 of the Executive Order. This action is not subject to 
Executive Order 13045 because it merely proposes to disapprove a SIP 
submission as not meeting the CAA.

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

    This action is not subject to Executive Order 13211, because it is 
not a significant regulatory action under Executive Order 12866.

I. National Technology Transfer and Advancement Act

    This rulemaking does not involve technical standards.

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

    The EPA believes the human health or environmental risk addressed 
by this

[[Page 9475]]

action will not have potential disproportionately high and adverse 
human health or environmental effects on minority, low-income or 
indigenous populations. This action merely proposes to disapprove a SIP 
submission as not meeting the CAA.

K. CAA Section 307(b)(1)

    Section 307(b)(1) of the CAA governs judicial review of final 
actions by the EPA. This section provides, in part, that petitions for 
review must be filed in the D.C. Circuit: (i) When the agency action 
consists of ``nationally applicable regulations promulgated, or final 
actions taken, by the Administrator,'' or (ii) when such action is 
locally or regionally applicable, if ``such action is based on a 
determination of nationwide scope or effect and if in taking such 
action the Administrator finds and publishes that such action is based 
on such a determination.'' For locally or regionally applicable final 
actions, the CAA reserves to the EPA complete discretion whether to 
invoke the exception in (ii).\49\
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    \49\ In deciding whether to invoke the exception by making and 
publishing a finding that an action is based on a determination of 
nationwide scope or effect, the Administrator takes into account a 
number of policy considerations, including his judgment balancing 
the benefit of obtaining the D.C. Circuit's authoritative 
centralized review versus allowing development of the issue in other 
contexts and the best use of agency resources.
---------------------------------------------------------------------------

    If the EPA takes final action on this proposed rulemaking the 
Administrator intends to exercise the complete discretion afforded to 
him under the CAA to make and publish a finding that the final action 
(to the extent a court finds the action to be locally or regionally 
applicable) is based on a determination of ``nationwide scope or 
effect'' within the meaning of CAA section 307(b)(1). Through this 
rulemaking action (in conjunction with a series of related actions on 
other SIP submissions for the same CAA obligations), the EPA interprets 
and applies section 110(a)(2)(d)(i)(I) of the CAA for the 2015 8-hour 
ozone NAAQS based on a common core of nationwide policy judgments and 
technical analysis concerning the interstate transport of pollutants 
throughout the continental U.S. In particular, the EPA is applying here 
(and in other proposed actions related to the same obligations) the 
same, nationally consistent 4-step framework for assessing good 
neighbor obligations for the 2015 8-hour ozone NAAQS. The EPA relies on 
a single set of updated, 2016-base year photochemical grid modeling 
results of the year 2023 as the primary basis for its assessment of air 
quality conditions and contributions at Steps 1 and 2 of that 
framework. Further, the EPA proposes to determine and apply a set of 
nationally consistent policy judgments to apply the 4-step framework. 
The EPA has selected a nationally uniform analytic year (2023) for this 
analysis and is applying a nationally uniform definition of 
nonattainment and maintenance receptors at Step 1, and a nationally 
uniform contribution threshold analysis at Step 2.\50\ For these 
reasons, the Administrator intends, if this proposed action is 
finalized, to exercise the complete discretion afforded to him under 
the CAA to make and publish a finding that this action is based on one 
or more determinations of nationwide scope or effect for purposes of 
CAA section 307(b)(1).\51\
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    \50\ A finding of nationwide scope or effect is also appropriate 
for actions that cover states in multiple judicial circuits. In the 
report on the 1977 Amendments that revised section 307(b)(1) of the 
CAA, Congress noted that the Administrator's determination that the 
``nationwide scope or effect'' exception applies would be 
appropriate for any action that has a scope or effect beyond a 
single judicial circuit. See H.R. Rep. No. 95-294 at 323, 324, 
reprinted in 1977 U.S.C.C.A.N. 1402-03.
    \51\ The EPA may take a consolidated, single final action on all 
of the proposed SIP disapproval actions with respect to obligations 
under CAA section 110(a)(2)(D)(i)(I) for the 2015 ozone NAAQS. 
Should EPA take a single final action on all such disapprovals, this 
action would be nationally applicable, and the EPA would also 
anticipate, in the alternative, making and publishing a finding that 
such final action is based on a determination of nationwide scope or 
effect.
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List of Subjects in 40 CFR Part 52

    Environmental protection, Air pollution control, Incorporation by 
reference, Ozone.

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

    Dated: February 7, 2022.
Diana Esher,
Acting Regional Administrator, Region III.
[FR Doc. 2022-02951 Filed 2-18-22; 8:45 am]
BILLING CODE 6560-50-P


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