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

CourtEnvironmental Protection Agency
Citation87 FR 9463
Published date22 February 2022
Record Number2022-02951
Federal Register, Volume 87 Issue 35 (Tuesday, February 22, 2022)
[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 [email protected]. 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
                [email protected].
                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, [email protected]. For the full EPA public
                comment policy, information about CBI or multimedia submissions, and
                general guidance on making effective comments, please visit https://www.epa.gov/dockets/commenting-epa-dockets. 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 ``NOX
                SIP Call,'' 63 FR 57356 (October 27, 1998), and the ``Clean Air
                Interstate Rule'' (CAIR), 70 FR 25162 (May 12, 2005).
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                C. Background on the EPA's Ozone Transport Modeling Information
                 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 (NOX) 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
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                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 NOX SIP Call
                have necessitated the application of a uniform framework of policy
                judgments in order to ensure an ``efficient and equitable'' approach.
                See EME Homer City Generation, LP v. EPA, 572 U.S. 489, 519 (2014).
                 In the March, August, and October 2018 memoranda, the EPA
                recognized that states may be able to establish alternative approaches
                to addressing their interstate transport obligations for the 2015 8-
                hour ozone NAAQS that vary from a nationally uniform framework. The EPA
                emphasized in these memoranda, however, that such alternative
                approaches must be technically justified and appropriate in light of
                the facts and circumstances of each particular state's submittal. In
                general, the EPA continues to believe that deviation from a nationally
                consistent approach to ozone transport must be substantially justified
                and have a well-documented technical basis that is consistent with
                relevant case law. Where states submitted SIPs that rely on any such
                potential ``flexibilities'' as may have been identified or suggested in
                the past, the EPA will evaluate whether the state adequately justified
                the technical and legal basis for doing so. The EPA'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
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                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\
                ---------------------------------------------------------------------------
                 \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)).
                ---------------------------------------------------------------------------
                 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 NOX 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
                NOX emission control and the state budgets for
                NOX 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 NOX
                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 NOX Rule met and exceeded the CSAPR Update
                requirements. Maryland claims that Maryland's NOX Rule
                controls EGU NOX emissions at levels more stringent than
                required by the CSAPR Update rule. The submittal notes that Maryland
                has implemented its NOX 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 NOX 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 NOX emitting facilities in the
                state along with an analysis of potential NOX emissions
                control technologies, their associated costs, estimated emissions
                reductions, and downwind air quality improvements.
                 Maryland's analysis instead focused on the CSAPR Update rule and
                described how, as of May 2017, that rule has reduced ozone season
                NOX emissions from power plants in 22 eastern states,
                including Maryland. Maryland referenced the EPA's finding in the CSAPR
                Update that for the updated NOX ozone season budgets for
                EGUs, an increased cost threshold of $1,400 per ton of NOX
                reduced was appropriate, because it represented the level of maximum
                marginal NOX 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 NOX
                budgets. That table shows that for Maryland, the CSAPR Update
                NOX 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 NOX 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 NOX Rule controls EGU
                NOX 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 NOX Rule to control
                NOX emissions from Coal-Fired EGUs, and the following
                description of the NOX Rule is taken largely from Maryland's
                submittal.\38\ Maryland's NOX 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
                NOX 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 NOX 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 NOX 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 NOX Rule, the sources are
                required to run their controls ``continuously.'' \40\
                ---------------------------------------------------------------------------
                 \37\ See Maryland's October 16, 2019 SIP submittal at 7 included
                in docket ID No. EPA-R03-OAR-2021-0872.
                 \38\ The Maryland NOX rule is codified at COMAR
                26.11.38 (Control of NOX 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.
                ---------------------------------------------------------------------------
                 In addition, Maryland's 2019 SIP Submission contains a table (Table
                5) \41\ which the State describes as listing ``NOX 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 NOX
                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).
                ---------------------------------------------------------------------------
                 \41\ Id. at 8.
                ---------------------------------------------------------------------------
                 Regarding Phase I of Maryland's NOX Rule, the EPA notes
                that the Phase I NOX 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 SO2, NOX, directly emitted
                particulate matter, CO2, 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\
                ---------------------------------------------------------------------------
                 \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.
                ---------------------------------------------------------------------------
                 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:
                ---------------------------------------------------------------------------
                 \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.
                ---------------------------------------------------------------------------
                 (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 NOX 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 NOX 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 NOX tonnage cap of
                21 tons per day for every day of the ozone season or meeting a system-
                wide NOX 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
                NOX 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 NOX 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.''
                ---------------------------------------------------------------------------
                 \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 NOX 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 NOX 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 NOX 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 NOX 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 NOX 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
                NOX emissions from EGUs, and other requirements to reduce
                NOX 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
                NOX 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 NOX 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 NOX 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 CO2 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
                NOX 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\
                ---------------------------------------------------------------------------
                 \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\
                ---------------------------------------------------------------------------
                 \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.
                ---------------------------------------------------------------------------
                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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