Document ID: EPA-R07-OAR-2021-0870-0001
Agency: epa
Document Type: Proposed Rule
Title: Air Quality State Implementation Plans; Approvals and Promulgations: Iowa; Interstate Transport of Air Pollution for the 2015 8-hour Ozone National Ambient Air Quality Standards
Posted Date: 2022-02-22T05:00Z

[Federal Register Volume 87, Number 35 (Tuesday, February 22, 2022)]
[Proposed Rules]
[Pages 9477-9484]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2022-02935]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

EPA-R07-OAR-2021-0870; EPA-HQ-OAR-2021-0663; FRL-9468-01-R7]

Air Plan Approval; Iowa; Interstate Transport of Air Pollution 
for the 2015 8-Hour Ozone National Ambient Air Quality Standards

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule and withdrawal of proposed rule.

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SUMMARY: The Clean Air Act (CAA) requires each State Implementation 
Plan (SIP) to contain adequate provisions prohibiting emissions that 
will significantly contribute to nonattainment or interfere with 
maintenance of air quality in other states. The State of Iowa made a 
submission to the Environmental Protection Agency (EPA or Agency) to 
address these requirements for the 2015 ozone National Ambient Air 
Quality Standards (NAAQS). EPA is proposing to approve the submission 
for Iowa as meeting the requirement that the SIP contains adequate 
provisions to prohibit emissions that will significantly contribute to 
nonattainment or interfere with maintenance of the 2015 ozone NAAQS in 
any other state. The EPA is also withdrawing its previous proposed rule 
to approve Iowa's SIP submission, as published in the Federal Register 
on March 2, 2020.

DATES: 
    Comments: Written comments on this proposed rule must be received 
on or before March 24, 2022.
    Withdrawal: As of February 22, 2022, the proposed rule published 
March 2, 2020, at 85 FR 12232, is withdrawn.

ADDRESSES: You may send comments, identified as Docket No. EPA-R07-OAR-
2021-0870, 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-R07-OAR-2021-0870 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: William Stone, Environmental 
Protection Agency, Region 7 Office, Air Quality Planning Branch, 11201 
Renner Boulevard, Lenexa, Kansas 66219; telephone number: (913) 551-
7714; email address: [email protected].

SUPPLEMENTARY INFORMATION: Public participation: Submit your comments, 
identified by Docket ID No. EPA-R07-OAR-2021-0870, at https://www.regulations.gov (our preferred method), or the other methods 
identified in the ADDRESSES section. Once submitted, comments cannot be 
edited or removed from the docket. The EPA may publish any comment 
received to its public docket. Do not submit to EPA's docket at https://www.regulations.gov any information 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

[[Page 9478]]

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-R07-OAR-2021-0870 
and EPA-HQ-OAR-2021-0663. Docket No. EPA-R07-OAR-2021-0870 contains 
information specific to Iowa, 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-R07-OAR-2021-
0870. For additional submission methods, please contact William Stone, 
(913) 551-7714, [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-R07-OAR-2021-0870, is available 
electronically at www.regulations.gov. While all documents in the 
docket are listed in the index, some information may not be publicly 
available due to docket file size restrictions or content (e.g., CBI).
    Throughout this document, ``we,'' ``us,'' and ``our'' means the 
EPA.

Table of Contents

I. Background
II. Iowa's SIP Submission Addressing Interstate Transport of Air 
Pollution for the 2015 8-Hour Ozone NAAQS
III. Withdrawal of Prior Proposed Approval
IV. EPA Evaluation of Iowa's Submission
V. Proposed Action
VI. Statutory and Executive Order Reviews

I. Background

A. Description of Statutory Background

    On October 1, 2015, the EPA promulgated a revision to the ozone 
NAAQS (2015 8-hour ozone NAAQS), lowering the level of both the primary 
and secondary standards to 0.070 parts per million (ppm).\1\ Section 
110(a)(1) of the CAA requires states to submit, within 3 years after 
promulgation of a new or revised standard, SIP submissions meeting the 
applicable requirements of section 110(a)(2).\2\ One of these 
applicable requirements is found in CAA section 110(a)(2)(D)(i)(I), 
otherwise known as the ``interstate transport'' or ``good neighbor'' 
provision, which generally requires SIPs to contain adequate provisions 
to prohibit in-state emissions activities from having certain adverse 
air quality effects on other states due to interstate transport of 
pollution. There are two so-called ``prongs'' within CAA section 
110(a)(2)(D)(i)(I). 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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B. Description of the EPA's Four Step Interstate Transport Regulatory 
Process

    The EPA is using the 4-step interstate transport framework (or 4-
step framework) to evaluate the state's SIP 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 (Aug. 8, 2011).
    \5\ Cross-State Air Pollution Rule Update for the 2008 Ozone 
NAAQS, 81 FR 74504 (Oct. 26, 2016).
    \6\ In 2019, the D.C. Circuit Court of Appeals remanded the 
CSAPR Update to the extent it failed to require upwind states to 
eliminate their significant contribution by the next applicable 
attainment date by which downwind states must come into compliance 
with the NAAQS, as established under CAA section 181(a). Wisconsin 
v. EPA, 938 F.3d 303, 313 (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

[[Page 9479]]

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 we requested comment on preliminary 
interstate ozone transport data including projected ozone design values 
and interstate contributions for 2023 using a 2011 base year 
platform.\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, we 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, we issued a memorandum (March 
2018 memorandum) noting that the same 2023 modeling data released in 
the October 2017 memorandum could also be useful for identifying 
potential downwind air quality problems with respect to the 2015 8-hour 
ozone NAAQS at Step 1 of the 4-step interstate transport framework.\11\ 
The March 2018 memorandum also included the then newly available 
contribution modeling data 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\ 82 FR at 1735.
    \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 or at https://www.epa.gov/node/194139/.
    \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 or at https://www.epa.gov/airmarkets/memo-and-supplemental-information-regarding-interstate-transport-sips-2015-ozone-naaqs.
    \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 or at https://www.epa.gov/airmarkets/memo-and-supplemental-information-regarding-interstate-transport-sips-2015-ozone-naaqs.
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    Since the release of the modeling data shared in the March 2018 
memorandum, the EPA performed updated modeling using a 2016-based 
emissions modeling platform (i.e., 2016v1). This emissions platform was 
developed under the EPA/Multi-Jurisdictional Organization (MJO)/state 
collaborative project.\14\ This collaborative project was a multi-year 
joint effort by the EPA, MJOs, and states to develop a new, more recent 
emissions platform for use by the EPA and states in regulatory modeling 
as an improvement over the dated 2011-based platform that the EPA had 
used to project ozone design values and contribution data provided in 
the 2017 and 2018 memoranda. The EPA used the 2016v1 emissions to 
project ozone design values and contributions for 2023. On October 30, 
2020, in the Notice of Proposed Rulemaking for the Revised CSAPR 
Update, the EPA released and accepted public comment on 2023 modeling 
that used the 2016v1 emissions platform.\15\ Although the Revised CSAPR 
Update addressed transport for the 2008 ozone NAAQS, the projected 
design values and contributions from the 2016v1 platform are also 
useful for identifying downwind ozone problems and linkages with 
respect to the 2015 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 2016 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, is described in the 
emissions modeling technical support document (TSD) for this proposed 
rule.\18\ The EPA performed air quality modeling of the 2016v2 
emissions using the most recent public release version of the 
Comprehensive Air-quality Model with extensions (CAMx) photochemical 
modeling, version 7.10.\19\ The EPA now proposes to primarily rely on 
modeling based on the updated and newly available 2016v2 emissions 
platform in evaluating these submissions with respect to Steps 1 and 2 
of the 4-step interstate transport framework and generally referenced 
within this action as 2016v2 modeling for 2023. By using the updated 
modeling results, the EPA is using the most current and technically 
appropriate information for this proposed rulemaking. Section III of 
this document and the Air Quality Modeling TSD for 2015 Ozone NAAQS 
Transport SIP Proposed Actions, included in Docket ID No. EPA-HQ-OAR-
2021-0663 for this proposal, contain additional detail on the EPA's 
2016v2 modeling. In this document, the

[[Page 9480]]

EPA is accepting public comment on this updated 2023 modeling, which 
uses a 2016v2 emissions platform. Comments on the EPA's air quality 
modeling should be submitted in the Regional docket for this action, 
docket ID No. EPA-R07-OAR-2021-0870. Comments are not 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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D. The EPA's Approach To Evaluating Interstate Transport SIPs for the 
2015 8-Hour Ozone NAAQS

    The EPA proposes to apply a consistent set of policy judgments 
across all states for purposes of evaluating interstate transport 
obligations and the approvability of interstate transport SIP 
submittals for the 2015 8-hour ozone NAAQS. These policy judgments 
reflect consistency with relevant case law and past agency practice as 
reflected in the CSAPR and related rulemakings. Nationwide consistency 
in approach is particularly important in the context of interstate 
ozone transport, which is a regional-scale pollution problem involving 
many smaller contributors. Effective policy solutions to the problem of 
interstate ozone transport going back to the NOX SIP Call 
have necessitated the application of a uniform framework of policy 
judgments in order to ensure an ``efficient and equitable'' approach. 
See EME Homer City Generation, LP v. EPA, 572 U.S. 489, 519 (2014).
    In the March, August, and October 2018 memoranda, the EPA 
recognized that states may be able to establish alternative approaches 
to addressing their interstate transport obligations for the 2015 8-
hour ozone NAAQS that vary from a nationally uniform framework. The EPA 
emphasized in these memoranda, however, that such alternative 
approaches must be technically justified and appropriate in light of 
the facts and circumstances of each particular state's submittal. In 
general, the EPA continues to believe that deviation from a nationally 
consistent approach to ozone transport must be substantially justified 
and have a well-documented technical basis that is consistent with 
relevant case law. Where states submitted SIPs that rely on any such 
potential ``flexibilities'' as may have been identified or suggested in 
the past, the EPA will evaluate whether the state adequately justified 
the technical and legal basis for doing so.
    The EPA notes that certain concepts included in an attachment to 
the March 2018 memorandum require unique consideration, and these ideas 
do not constitute agency guidance with respect to transport obligations 
for the 2015 ozone NAAQS. Attachment A to the March 2018 memorandum 
identified a ``Preliminary List of Potential Flexibilities'' that could 
potentially inform SIP development.\20\ However, EPA made clear in that 
Attachment that the list of ideas were not suggestions endorsed by the 
Agency but rather ``comments provided in various forums'' on which EPA 
sought ``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 are we 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, 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 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 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 Aug. 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\ We note that the court in Maryland did not have occasion to 
evaluate circumstances in which the EPA may determine that an upwind 
linkage to a downwind air quality problem exists at steps 1 and 2 of 
the interstate transport framework by a particular attainment date, 
but for reasons of impossibility or profound uncertainty the Agency 
is unable to mandate upwind pollution controls by that date. See 
Wisconsin, 938 F.3d at 320. The D.C. Circuit noted in Wisconsin that 
upon a sufficient showing, these circumstances may warrant 
flexibility in effectuating the purpose of the interstate transport 
provision.
    \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 Aug. 3, 2018).
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    The EPA recognizes that the attainment date for nonattainment areas 
classified as Marginal for the 2015 8-

[[Page 9481]]

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, we proceed to the next 
step of our 4-step interstate transport framework by identifying the 
upwind state's contribution to those receptors.
    The EPA's approach to identifying ozone nonattainment and 
maintenance receptors in this action is consistent with the approach 
used in previous transport rulemakings. The EPA's approach gives 
independent consideration to both the ``contribute significantly to 
nonattainment'' and the ``interfere with maintenance'' prongs of CAA 
section 110(a)(2)(D)(i)(I), consistent with the D.C. Circuit's 
direction in North Carolina v. EPA.\26\
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    \26\ See North Carolina v. EPA, 531 F.3d at 910-11 (holding that 
the EPA must give ``independent significance'' to each prong of CAA 
section 110(a)(2)(D)(i)(I)).
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    For the purpose of this proposal, the EPA identifies nonattainment 
receptors as those monitoring sites that are projected to have average 
design values that exceed the NAAQS and that are also measuring 
nonattainment based on the most recent monitored design values. This 
approach is consistent with prior transport rulemakings, such as the 
CSAPR Update, where the EPA defined nonattainment receptors as those 
areas that both currently measure nonattainment and that the EPA 
projects will be in nonattainment in the future analytic year (i.e., 
2023).\27\
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    \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 EPA's approach to defining 
nonattainment in CAIR).
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    In addition, in this proposal, the EPA identifies a receptor to be 
a ``maintenance'' receptor for purposes of defining interference with 
maintenance, consistent with the method used in the CSAPR and upheld by 
the D.C. Circuit in EME Homer City Generation, L.P. v. EPA, 795 F.3d 
118, 136 (D.C. Cir. 2015).\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. EPA interprets the 
projected maximum future design value to be a potential future air 
quality outcome consistent with the meteorology that yielded maximum 
measured concentrations in the ambient data set analyzed for that 
receptor (i.e., ozone conducive meteorology). EPA also recognizes that 
previously experienced meteorological conditions (e.g., dominant wind 
direction, temperatures, air mass patterns) promoting ozone formation 
that led to maximum concentrations in the measured data may reoccur in 
the future. The maximum design value gives a reasonable projection of 
future air quality at the receptor under a scenario in which such 
conditions do, in fact, reoccur. The projected maximum design value is 
used to identify upwind emissions that, under those circumstances, 
could interfere with the downwind area's ability to maintain the NAAQS.
---------------------------------------------------------------------------

    \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 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

[[Page 9482]]

anthropogenic sources in the U.S. results from the combined impact of 
relatively small contributions from many upwind states, along with 
contributions from in-state sources and, in some cases, substantially 
larger contributions from a subset of particular upwind states. The 
EPA's analysis shows that much of the ozone transport problem being 
analyzed in this proposed rule is still the result of the collective 
impacts of contributions from many upwind states. Therefore, 
application of a consistent contribution threshold is necessary to 
identify those upwind states that should have responsibility for 
addressing their contribution to the downwind nonattainment and 
maintenance problems to which they collectively contribute. Continuing 
to use 1 percent of the NAAQS as the screening metric to evaluate 
collective contribution from many upwind states also allows the EPA 
(and states) to apply a consistent framework to evaluate interstate 
emissions transport under the interstate transport provision from one 
NAAQS to the next. See 81 FR 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; CSAPR, 76 FR 48208, 48246-63; CAIR, 
70 FR 25162, 25195-229; or the NOX SIP Call, 63 FR 57356, 
57399-405. See also Revised CSAPR Update, 86 FR 23054, 23086-23116. 
Consistently across these rulemakings, the EPA has developed 
emissions inventories, analyzed different levels of control 
stringency at different cost thresholds, and assessed resulting 
downwind air quality improvements.
---------------------------------------------------------------------------

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

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

    On November 30, 2018, Iowa submitted a SIP revision addressing the 
CAA section 110(a)(2)(D)(i)(I) interstate transport requirements for 
the 2015 ozone NAAQS. Iowa chose to rely on the results of EPA's 2023 
modeling, as presented in the March 2018 memorandum, to identify 
downwind nonattainment and maintenance receptors that may be impacted 
by emissions from sources in Iowa. Based on Iowa's review of the EPA's 
modeling assumptions and model performance evaluation, Iowa determined 
that EPA's future year projections were appropriate for purposes of 
evaluating Iowa's impact on attainment and maintenance of the 2015 
ozone NAAQS in other states.
    Iowa relied on EPA's 2023 modeling to conclude that the state does 
not contribute significantly to nonattainment or interfere with 
maintenance of the 2015 ozone NAAQS in any other state. Iowa referred 
to the analytic information in EPA's August 2018 memorandum as a basis 
to use a 1 ppb contribution threshold when evaluating the state's 
contribution to downwind receptors at Step 2 of EPA's four-step 
interstate transport framework. Using EPA's modeling, Iowa identified 
that it is projected to contribute below 1 percent of the 2015 ozone 
NAAQS (i.e., less than 0.70 ppb) to all but two downwind receptors: The 
nonattainment receptor in Milwaukee County, Wisconsin (Milwaukee 
receptor), and the maintenance-only receptor in Allegan County, 
Michigan (Allegan receptor). Iowa's contribution to these two receptors 
was projected to be between 1 percent and 1 ppb. Iowa concluded that 1 
ppb is an appropriate contribution threshold to apply with respect to 
the 2015 ozone NAAQS and that Iowa's emissions therefore do not 
contribute to nonattainment or maintenance problems at either receptor.
    Iowa noted that its 2023 modeled contribution to the Milwaukee 
receptor is 0.79 ppb, and its 2023 modeled contribution to the Allegan 
receptor is 0.77 ppb. Iowa further noted that application of the 1 ppb 
threshold captures 83 percent of the upwind contribution captured at 
the 1 percent threshold at the Milwaukee receptor and 94 percent of the 
upwind contribution

[[Page 9483]]

captured at the 1 percent threshold at the Allegan receptor. Based on 
these data, Iowa concluded that the 1 ppb threshold is therefore 
appropriate because it captures a ``substantial portion'' of the 
transported contribution from upwind states when compared to the 1 
percent threshold at both receptors. Because the state's impact on both 
receptors was projected to be below the 1 ppb threshold, the state 
concluded that its emissions will not contribute significantly to 
nonattainment or interfere with maintenance of the 2015 ozone NAAQS in 
downwind states.

III. Withdrawal of Prior Proposed Approval

    On March 2, 2020, EPA proposed to approve portions of the 
infrastructure SIP submission received from the State of Iowa on 
November 30, 2018, in accordance with section 110(a)(1) of the CAA. In 
the document, the EPA proposed to approve the portion of the SIP 
addressing section 110(a)(2)(D)(i)(I)--significant contribution to 
nonattainment (prong 1), and interference with maintenance of the NAAQS 
(prong 2). This proposal relied on results of EPA's 2023 modeling, as 
presented in the March 2018 memorandum explained above, as well as the 
State's argument for using the 1 ppb threshold in Step 2 rather than 
the 1 percent threshold. The action received two adverse comments. In 
this document, we are withdrawing our March 2, 2020, proposed approval. 
We are now reproposing approval based on new modeling and a new 
rationale for approval based on that new modeling, as discussed in 
section IV.

IV. EPA Evaluation of Iowa's Submission

    Iowa's SIP submission relies on analysis of the year 2023 (using a 
2011 base year platform) to conclude that the State does not 
significantly contribute to nonattainment or interfere with maintenance 
of the 2015 ozone NAAQS in any other state. As explained in section I 
of this proposal, the EPA has conducted an updated analysis for the 
2023 analytical year (using a 2016 base year platform) and proposes to 
rely primarily on this updated modeling to evaluate Iowa's transport 
SIP submission.
    As described in section I, the EPA performed air quality modeling 
to project design values and contributions for 2023 using the 2016v2 
emissions platform. The design values and contributions were examined 
to determine if Iowa contributes at or above the threshold of 1 percent 
of the 2015 ozone NAAQS (0.70 ppb) to any downwind nonattainment or 
maintenance receptor. The data \30\ indicate that the highest 
contribution in 2023 from Iowa to a downwind nonattainment and 
maintenance receptors is 0.64 ppb and 0.58 ppb, respectively.\31\
---------------------------------------------------------------------------

    \30\ 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.
    \31\ The EPA's analysis indicates that Iowa will have a 0.64 ppb 
impact at the projected nonattainment receptor in Kenosha County, 
Wisconsin (Site ID 550590019), which has a 2023 projected average 
design value of 72.8 ppb and a 2023 projected maximum design value 
of 73.7 ppb. The EPA's analysis further indicates that Iowa will 
have a 0.58 ppb impact at a projected maintenance receptor in Cook 
County, Illinois (Site ID 170310032), which has which has a 
projected 2023 average design value of 69.8 ppb and a 2023 projected 
maximum design value of 72.4 ppb.
---------------------------------------------------------------------------

    Based on the EPA's updated modeling, it is no longer necessary to 
evaluate Iowa's use of 1 ppb as a contribution threshold at Step 2. The 
state is projected to contribute less than a 1 percent threshold. While 
the EPA does not, in this action, approve of the state's application of 
the 1 ppb threshold, based on the state's contributions of less than 1 
percent to projected downwind nonattainment or maintenance receptors, 
the state's use of this alternative threshold is inconsequential to our 
action on this SIP submittal. The EPA is proposing to approve Iowa's 
SIP submission on the basis of the use of a 1 percent contribution 
threshold at Step 2.
    The EPA's evaluation of measured and monitored data and 
contribution values in 2023, as discussed in this section, is 
consistent with conclusions made by Iowa that emissions from sources in 
the State will not contribute to nonattainment or interfere with 
maintenance of the 2015 ozone NAAQS in any other state.

V. Proposed Action

    The EPA is proposing to approve a portion of Iowa's November 30, 
2018, SIP submittal as meeting the interstate transport requirements of 
CAA section 110(a)(2)(D)(i)(I) for the 2015 ozone NAAQS. The EPA has 
addressed the remaining infrastructure elements included in Iowa's 
submittal in a separate action. Additionally, this proposal withdraws 
and replaces EPA's March 2, 2020, proposed rule as discussed in section 
III.
    The Agency is soliciting public comments on its proposed approval 
of the CAA section 110(a)(2)(D)(i)(I) element of Iowa's infrastructure 
SIP submittal for the 2015 ozone NAAQS. Significant comments will be 
considered before taking final action. Interested parties may 
participate in the Federal rulemaking procedure by submitting written 
comments to this proposed rule by following the instructions listed in 
the ADDRESSES section of this Federal Register.

VI. Statutory and Executive Order Reviews

    Under the Clean Air Act, the Administrator is required to approve a 
SIP submission that complies with the provisions of the Act and 
applicable Federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a). 
Thus, in reviewing SIP submissions, EPA's role is to approve state 
choices, provided that they meet the criteria of the CAA. Accordingly, 
this proposed action merely approves state law as meeting Federal 
requirements and does not impose additional requirements beyond those 
imposed by state law. For that reason, this proposed action:
     Is not a significant regulatory action subject to review 
by the Office of Management and Budget under Executive Orders 12866 (58 
FR 51735, October 4, 1993) and 13563 (76 FR 3821, January 21, 2011);
     Does not impose an information collection burden under the 
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
     Is certified as not having a significant economic impact 
on a substantial number of small entities under the Regulatory 
Flexibility Act (5 U.S.C. 601 et seq.);
     Does not contain any unfunded mandate or significantly or 
uniquely affect small governments, as described in the Unfunded 
Mandates Reform Act of 1995 (Pub. L. 104-4);
     Does not have federalism implications as specified in 
Executive Order 13132 (64 FR 43255, August 10, 1999);
     Is not an economically significant regulatory action based 
on health or safety risks subject to Executive Order 13045 (62 FR 
19885, April 23, 1997);
     Is not a significant regulatory action subject to 
Executive Order 13211 (66 FR 28355, May 22, 2001);
     Is not subject to requirements of section 12(d) of the 
National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272 
note) because application of those requirements would be inconsistent 
with the Clean Air Act; and
     Does not provide EPA with the discretionary authority to 
address, as appropriate, disproportionate human health or environmental 
effects, using practicable and legally permissible

[[Page 9484]]

methods, under Executive Order 12898 (59 FR 7629, February 16, 1994).
    In addition, the SIP is not approved to apply on any Indian 
reservation land or in any other area where EPA or an Indian tribe has 
demonstrated that a tribe has jurisdiction. In those areas of Indian 
country, the rule does not have tribal implications and will not impose 
substantial direct costs on tribal governments or preempt tribal law as 
specified by Executive Order 13175 (65 FR 67249, November 9, 2000).

List of Subjects in 40 CFR Part 52

    Environmental protection, Air pollution control, Incorporation by 
reference, Intergovernmental relations, Nitrogen dioxide, Ozone, 
Reporting and recordkeeping requirements, Volatile organic compounds.

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

    Dated: February 1, 2022.
Meghan A. McCollister,
Regional Administrator, Region 7.

    Part 52 of chapter I, title 40 of the Code of Federal Regulations 
is proposed to be amended as follows:

PART 52--APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS

0
1. The authority citation for part 52 continues to read as follows:

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

Subpart Q--Iowa

0
2. In Sec.  52.820, the table in paragraph (e) is amended by adding an 
entry for ``(55)'' in numerical order to read as follows:

Sec.  52.820  Identification of plan.

* * * * *
    (e) * * *

                                   EPA-Approved Iowa Nonregulatory Provisions
----------------------------------------------------------------------------------------------------------------
                                                              State
    Name of non regulatory SIP     Applicable  geographic   submittal    EPA approval date       Explanation
            provision               or nonattainment area      date
----------------------------------------------------------------------------------------------------------------
 
                                                  * * * * * * *
(55) Transport SIP for the 2015    Statewide.............   11/30/2018  [Date of             [EPA-R07-OAR-2021-0
 Ozone Standard.                                                         publication of the   870; EPA-HQ-OAR-
                                                                         final rule in the    2021-0663; FRL-
                                                                         [Federal             9468-01-R7]. This
                                                                         Register],           transport SIP
                                                                         [Federal Register    shows that Iowa
                                                                         citation of the      does not
                                                                         final rule].         significantly
                                                                                              contribute to
                                                                                              ozone
                                                                                              nonattainment or
                                                                                              maintenance in any
                                                                                              other state. This
                                                                                              submittal is
                                                                                              approved as
                                                                                              meeting the
                                                                                              requirements of
                                                                                              Clean Air Act
                                                                                              section
                                                                                              110(a)(2)(D)(i)(I)
                                                                                              .
----------------------------------------------------------------------------------------------------------------

[FR Doc. 2022-02935 Filed 2-18-22; 8:45 am]
BILLING CODE 6560-50-P