Air Plan Disapproval; Missouri Interstate Transport of Air Pollution for the 2015 8-Hour Ozone National Ambient Air Quality Standards, 9533-9545 [2022-03183]
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Federal Register / Vol. 87, No. 35 / Tuesday, February 22, 2022 / Proposed Rules
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
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.
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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).66
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
66 In deciding whether to invoke the exception by
making and publishing a finding that an action is
based on a determination of nationwide scope or
effect, the Administrator takes into account a
number of policy considerations, including his
judgment balancing the benefit of obtaining the D.C.
Circuit’s authoritative centralized review versus
allowing development of the issue in other contexts
and the best use of agency resources.
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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 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 approach to
nonattainment and maintenance
receptors and a nationally uniform
approach to contribution threshold
analysis.67
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).68
67 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.
68 The EPA may take a consolidated, single final
action on all of the proposed SIP disapproval
actions with respect to obligations under CAA
section 110(a)(2)(D)(i)(I) for the 2015 ozone
NAAQS. Should EPA take a single final action on
all such disapprovals, this action would be
nationally applicable, and the EPA would also
anticipate, in the alternative, making and
publishing a finding that such final action is based
on a determination of nationwide scope or effect.
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List of Subjects in 40 CFR Part 52
Environmental protection, Air
pollution control, Incorporation by
reference, Ozone.
Authority: 42 U.S.C. 7401 et seq.
Dated: February 7, 2022
Diana Esher,
Acting Regional Administrator, Region III.
[FR Doc. 2022–02952 Filed 2–18–22; 8:45 am]
BILLING CODE 6560–50–P
ENVIRONMENTAL PROTECTION
AGENCY
40 CFR Part 52
EPA–R07–OAR–2021–0851; EPA–HQ–OAR–
2021–0663; FRL–9425–01–R7]
Air Plan Disapproval; Missouri
Interstate Transport of Air Pollution for
the 2015 8-Hour Ozone National
Ambient Air Quality Standards
Environmental Protection
Agency (EPA).
ACTION: Proposed rule.
AGENCY:
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 Missouri regarding interstate
transport for the 2015 8-hour ozone
national ambient air quality standards
(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 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–R07–
OAR–2021–0851, by any of the
following methods: Federal
eRulemaking Portal at https://
SUMMARY:
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www.regulations.gov following the
online nstructions for submitting
comments or via email to
stone.william@epa.gov. Include Docket
ID No. EPA–R07–OAR–2021–0851 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: stone.william@epa.gov.
SUPPLEMENTARY INFORMATION: Public
participation: Submit your comments,
identified by Docket ID No. EPA–R07–
OAR–2021–0851, 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
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–2021–0851 and
EPA–HQ–OAR–2021–0663. Docket No.
EPA–R07–OAR–2021–0851 contains
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information specific to Missouri,
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 8hour 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–
0851. For additional submission
methods, please contact William Stone,
(913) 551–7714, stone.william@epa.gov.
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–
2021–0851, 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.
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
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.
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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 socalled ‘‘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
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
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).
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
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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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C. Background on the EPA’s Ozone
Transport Modeling Information
The EPA has released several
documents containing information
relevant to evaluating interstate
transport with respect to the 2015 8hour 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 (DVs) 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
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).
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).
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.
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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
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 4step 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
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 the
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-andcomment 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
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9535
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/MultiJurisdictional 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
DVs 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 See 85 FR 68964,
68981. 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
Following the Revised CSAPR Update
final rule, 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
Standards, October 19, 2018, available in docket ID
No. EPA–HQ–OAR–2021–0663.
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.
17 Additional details and documentation related
to the MOVES3 model can be found at https://
www.epa.gov/moves/latest-version-motor-vehicleemission-simulator-moves.
18 See Technical Support Document (TSD)
Preparation of Emissions Inventories for the 2016v2
North American Emissions Modeling Platform
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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. with the 2016
base year and 2023 future year
emissions developed as part of the
2016v2 emissions platform.19 The EPA
now proposes to rely on modeling based
on the updated and newly available
2016v2 air quality modeling in
evaluating these submissions with
respect to Steps 1 and 2 of the 4-step
interstate transport framework. 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 included in the docket
for this proposal contain additional
detail on the modeling performed using
the 2016v2 emissions. In this document,
the EPA is accepting public comment on
this updated 2023 modeling, which uses
a 2016 emissions platform. Details on
the air quality modeling and the
methods for projecting design values
and determining contributions in 2023
are described in the Air Quality
Modeling TSD for 2015 Ozone NAAQS
Transport SIP Proposed Actions.
Comments on the EPA’s air quality
modeling should be submitted in the
Regional docket for this action, docket
ID No. EPA–R07–OAR–2021–0851.
Comments are not being accepted in
docket EPA–HQ–OAR–2021–0663.
States may have chosen to rely on the
results of the EPA modeling and/or
alternative modeling performed by
states or Multi-Jurisdictional
Organizations (MJOs) to evaluate
downwind air quality problems and
contributions as part of their
submissions. In section III we evaluate
how Missouri used air quality modeling
information in their submission.
D. The EPA’s Approach to Evaluating
Interstate Transport SIPs for the 2015 8Hour 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
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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consistency in approach is particularly
important in the context of interstate
ozone transport, which is a regionalscale 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,
the 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 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 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
20 March
21 Id.
2018 memorandum, Attachment A.
at A–1.
22 Id.
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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.
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.
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
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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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.
The EPA recognizes that the
attainment date for nonattainment areas
classified as Marginal for the 2015 8hour 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 23074; see also
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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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
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
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
26 See North Carolina v. EPA, 531 F.3d 896, 910–
11 (D.C. Cir. 2008) (holding that the EPA must give
‘‘independent significance’’ to each prong of CAA
section 110(a)(2)(D)(i)(I)).
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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9537
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
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.
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. Consistent with
the methodology described for
nonattainment, those sites that are
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).
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currently measuring ozone
concentrations below the level of the
applicable NAAQS, but that are
projected to be nonattainment based on
the average or maximum design values,
are identified as maintenance-only
receptors.
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, portion of
the nonattainment problems from
anthropogenic sources in the U.S.
results from the combined impact of
relatively small contributions from
many upwind states, along with
contributions from in-state sources and,
in some cases, substantially larger
contributions from a subset of particular
upwind states. 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,
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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
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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 welldocumented 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
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. SIP Submission Addressing
Interstate Transport of Air Pollution for
the 2015 8-Hour Ozone NAAQS
On June 10, 2019, the Missouri
Department of Natural Resources’ Air
Pollution Control Program (MoDNR)
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.
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made a SIP submission to address
interstate transport of air pollution for
the 2015 8-hour ozone NAAQS.
MoDNR’s good neighbor SIP submission
for the 2015 ozone NAAQS relied on the
EPA’s four-step approach and
corresponding memoranda for
determining obligations for upwind
states to limit transported air pollution
to downwind states. The State
concluded that emissions from sources
or emissions activity in Missouri will
not contribute significantly to
nonattainment or interfere with
maintenance of the 2015 ozone NAAQS
in any downwind states.
In its analysis, the state relied on the
EPA’s modeling released with the
March 2018 memorandum to identify
nonattainment and maintenance
receptors in 2023 (Step 1). The State
also relied on the EPA’s modeling from
the March 2018 memorandum to
identify which monitors were then
linked to emissions from Missouri. In its
submission, the MoDNR identified all of
the nonattainment and maintenance
receptors to which Missouri was
projected to contribute more than 0.70
ppb to the 2023 DV. Table 1 provides
information on the six nonattainment
and maintenance receptors identified by
the MoDNR.
TABLE 1—2023 AVERAGE AND MAXIMUM DESIGN VALUES AT DOWNWIND RECEPTORS WITH MISSOURI CONTRIBUTIONS
LARGER THAN 0.70 PPB
2023
Average DV
(ppb)
Site
(monitor, county, state)
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260050003, Allegan, MI ..................................................................
261630019, Wayne, MI ...................................................................
484392003, Brazoria, TX ................................................................
482011039, Harris, TX ....................................................................
550790085 Milwaukee, WI ..............................................................
551170006, Sheboygan, WI ............................................................
The state analyzed each of the six
receptors in Table 1 using information
in the EPA’s 2018 guidance memoranda
described above. For the two receptors
in Texas, the state observed that the
total upwind state contribution is
approximately 13 ppb to both of these
Texas receptors and that Texas’ in-state
contribution to these two receptors is 26
ppb to the Brazoria County receptor and
22.6 ppb to the Harris County receptor.
The MoDNR combined the
contributions from initial/boundary
conditions with the contribution from
biogenic emissions to show that the
contribution from these two categories
is over 52 ppb, at these two receptors.
Based on this information, the MoDNR
claimed that the ozone problems at
these two receptors are not caused by
upwind U.S. anthropogenic emissions
from other states, but rather that in-state
contributions, natural ozone
concentrations, and international
emissions are the likely significant
contributors to the problem at these two
sites.
The MoDNR also noted that its
contribution to the projected 2023 ozone
DV at the two Texas receptors is 0.88
ppb. The MoDNR then referenced
statements in the EPA’s August 2018
memorandum on the use of alternative
thresholds that a 1 ppb threshold would
generally capture a substantial amount
of transported contribution from
upwind states to the downwind
monitors. The MoDNR concluded that 1
ppb is, therefore, an appropriate
alternative screening threshold for
evaluating whether emissions in their
state are linked to the ozone problems
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2023
Maximum DV
(ppb)
69.0
69.0
74.0
71.8
71.2
72.8
71.7
71.0
74.9
73.5
73.0
75.1
at these two receptors. Based on this
alternative threshold, the State
determined that it will not contribute
significantly to these nonattainment
receptors in 2023. The MoDNR then
concluded that its SIP sufficiently
addresses the good neighbor obligation
for the 2015 ozone NAAQS with respect
to these two Texas receptors based only
on its Step 2 weight of evidence
analysis.
For the Milwaukee, Wisconsin
receptor, the MoDNR noted that its
projected contribution to this receptor is
0.93 ppb, and thus less than 1 ppb. The
State observed that the 1 ppb threshold
would capture 79.4 percent of the total
contribution from all upwind states and
that the contribution captured by the 1
ppb threshold is 83 percent of the
amount captured by the 0.70 ppb
threshold at this receptor. The state
asserted that the 1 ppb threshold would
capture a substantial amount of total
upwind states’ contribution to ozone
concentrations at this receptor, which
will lead to meaningful emission
reductions to ensure attainment of the
NAAQS at this monitor in 2023.
Therefore, the MoDNR relied on a 1 ppb
threshold to conclude that its existing
SIP sufficiently addresses the good
neighbor obligation for the 2015 ozone
NAAQS with respect to this receptor.
For the Wayne, Michigan site, the
state observed that the 1 ppb threshold
captures 61.8 percent of total upwind
state contributions and the contribution
captured by the 1 ppb threshold would
constitute 92.2 percent of the total
contribution that would be captured by
the 0.70 ppb threshold. The state
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Missouri
contribution
(ppb)
2.61
0.92
0.88
0.88
0.93
1.37
Comments
Maintenance receptor.
Maintenance receptor.
Nonattainment receptor.
Nonattainment receptor.
Nonattainment receptor.
Nonattainment receptor.
asserted that the 1 ppb threshold will
capture a substantial amount of upwind
states’ contribution to the ozone
concentrations at this site, which will
lead to meaningful emission reductions
that will help ensure attainment of the
NAAQS at this receptor in 2023. The
MoDNR noted that its projected
contribution to the Wayne, Michigan
receptor is 0.92 ppb, and thus less than
1 ppb. Therefore, the MoDNR concluded
that its existing SIP sufficiently
addresses the good neighbor obligation
for the 2015 ozone NAAQS with respect
to this receptor based only on this Step
2 weight of evidence analysis.
For the Sheboygan, Wisconsin site,
the State observed that the 1 ppb
threshold would capture 79.4 percent of
the total upwind contributions and that
a 2 ppb threshold would capture 68.2
percent of the total upwind state
contributions. The State also observed
that an alternative 2 ppb threshold
would capture 85.9 percent of the
upwind state contributions captured
under a 1 ppb threshold. Using these
data, the MoDNR asserted that a 2 ppb
threshold is appropriate because it
would capture nearly 70 percent of the
total upwind state contributions and
thus would result in meaningful
emission reductions that will help to
ensure attainment of the NAAQS at the
site by 2023. The state also asserted that
the primary contributors to the
projected ozone concentrations at the
monitor in Sheboygan include
emissions from Illinois, Indiana, and
Wisconsin. The MoDNR cited the EPA
modeling projecting that emissions from
these states would contribute a
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combined 31.93 ppb in 2023 to the
Sheboygan receptor.
For the Sheboygan receptor, the
MoDNR also pointed to the Lake
Michigan Air Director’s Consortium’s
(LADCO’s) interstate transport modeling
results for the 2015 ozone NAAQS. The
State noted that LADCO’s analysis also
indicates that the ozone levels at the
Wisconsin shoreline of Lake Michigan
are heavily affected by the emissions
from Illinois, Indiana, and Wisconsin.30
The MoDNR further pointed out that
the other monitoring site in Sheboygan
County (551170009), which is a few
miles further inland than the Sheboygan
nonattainment receptor, has no
projected problems with attaining and
maintaining compliance with the 2015
ozone NAAQS. The MoDNR concluded
that the nonattainment receptor in
Sheboygan is heavily influenced by
local transport emissions and lake
breeze effects over Lake Michigan. The
State asserted that use of a 2 ppb
threshold would capture a substantial
amount of upwind states’ contribution
to the ozone concentrations at this site,
which will lead to meaningful emission
reductions that will help ensure
attainment of the NAAQS at this
monitor in 2023. The MoDNR noted that
its projected contribution to the
Sheboygan, Wisconsin receptor is 1.37
ppb, which is less than 2 ppb.
Therefore, the MoDNR concluded that
its existing SIP sufficiently addresses
the good neighbor obligation for the
2015 ozone NAAQS with respect to the
Sheboygan receptor based only on this
Step 2 weight of evidence analysis.
For the Allegan, Michigan receptor,
the MoDNR used an analysis based on
information in the EPA’s October 2018
memorandum on alternative approaches
for identifying maintenance receptors to
claim that the Allegan monitoring site
will not be a receptor in 2023.
Specifically, rather than rely upon the
EPA’s projected 2023 maximum design
value for identifying maintenance
receptors, the state used an alternative
approach that included projected 2023
ozone concentrations based on a 2-year
base period (2010–2011), a 3-year base
period (2009–2011) and a 4-year base
period (2009–2012) to demonstrate that
the Allegan monitoring site would attain
the standard by 2023. To support the
use of these alternative base periods, the
State provided an analysis for the three
consideration outlined in the August
2018 memorandum: (i) Meteorological
30 Interstate Transport Modeling for the 2015
Ozone National Ambient Air Quality Standard, the
technical support document (TSD), https://
www.ladco.org/wp-content/uploads/Documents/
Reports/TSDs/O3/LADCO_2015O3iSIP_TSD_
13Aug2018.pdf.
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conditions in the area of the monitoring
site were conducive to ozone formation
during the alternative base period
design value used for projections; (ii)
ozone concentrations have been
trending downward at the site since
2011 (and ozone precursor emissions of
NOX and VOCs have also decreased);
and (iii) emissions are expected to
continue to decline in the upwind and
downwind states out to the attainment
date of the site. The MoDNR noted that
ozone concentrations during the
summer of 2009 were well below
normal for the state of Michigan despite
having a large number of days during
the ozone season where they claim that
meteorology was conducive to ozone
formation. The MoDNR also noted that
the summer of 2012 was among the
most ozone conducive summers across
the entire Midwestern portion of the
country. MoDNR suggested that the
variation in the degree of ozone
conducive meteorology between 2009
and 2012 would counterbalance in the
alternative baseline period.
The State provided an analysis
showing ozone concentrations trending
down since 2012 at the Allegan monitor.
The State also provided the total
statewide anthropogenic NOX and VOC
emissions (ozone precursors) in
Michigan, Missouri, and two
neighboring states that are upwind of
the Allegan monitor during 2011 and
2017 (i.e., Illinois and Indiana), which
showed that emissions in all four of
these states went down during this time
period.
The MoDNR concluded that the
Allegan receptor meets all the criteria
listed in the EPA October memorandum
relating to alternative methods for
identifying maintenance receptors.
Based on this analysis, the MoDNR
asserted that the Allegan Michigan
monitor should not be a maintenance
receptor for purposes of the 2015 ozone
NAAQS. Therefore, the State found that
the Missouri’ existing SIP fully
addresses the CAA good neighbor
obligation with respect to the Allegan,
Michigan receptor.
Based on the analysis above, the
MoDNR concluded that its current SIP
adequately addresses the state’s
obligation under CAA section
110(a)(2)(D)(i)(I) (the good neighbor
provision) with respect to the 2015
ozone NAAQS. The MoDNR stated that
it has demonstrated that its SIP
submittal ensures that emissions in
Missouri will not significantly
contribute to nonattainment or interfere
with maintenance of the 2015 ozone
NAAQS in any downwind state. Based
on this conclusion, the MoDNR
concluded its analysis at Step 2 of the
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4-step interstate transport framework
and provided no analysis for steps 3 or
4.
III. EPA Evaluation
The EPA is proposing to find that the
June 10, 2019, SIP submission from the
MoDNR does not meet the State’s
obligations with respect to prohibiting
emissions that contribute significantly
to nonattainment or interfere with
maintenance of the 2015 8-hour ozone
NAAQS in any other state based on the
EPA’s evaluation of the SIP submission
using the 4-step interstate transport
framework, and the EPA is therefore
proposing to disapprove Missouri’s
submission.
A. Missouri
1. Evaluation of Information Provided
by the MoDNR Regarding Step 1
At Step 1 of the 4-Step interstate
transport framework, the MoDNR relied
on the EPA modeling released in the
March 2018 memorandum to identify
nonattainment and maintenance
receptors in 2023. As correctly noted in
the MoDNR SIP submittal, the EPA’s
prior analysis indicated that the State
was linked to six nonattainment and/or
maintenance receptors in three
downwind states in 2023 (identified in
Table 1 of this action). In its October
2018 memorandum on alternative
maintenance receptors, the EPA
suggested that States could provide
meteorological data, among other data,
to support potential alternative
methodologies or flexibilities to identify
maintenance receptors. The MoDNR
utilized this flexibility to eliminate the
Allegan, Michigan maintenance receptor
(monitor ID 260050003) based on the
use of alternative base year periods. The
State considered three alternative base
periods as a basis for projecting design
values in 2023. These based periods
include (1) a 2-year base period using
4th high ozone concentrations in 2010
and 2011, (2) a 3-year base year period
from 2009–2011, and (3) a 4-year base
year period from 2009–2012. As an
initial matter, design values, by
definition are based on the average of
the 4th highest maximum daily 8-hour
ozone concentration in three
consecutive years. The ‘‘pseudo’’ design
values calculated by the State using 2
years of data, when data for the third
year (i.e., 2009) were clearly available,
and using 4 years of data do not
constitute alternative design values. In
this regard, the approach by the State
using these two alternatives runs
counter to the approach identified in the
October 2018 memorandum: ‘‘. . . .
EPA believes that a state may, in some
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cases, use a design value from the base
period that is not the maximum design
value.’’
The State also provided information
and analysis of meteorological data to
attempt to establish that all years that
constitute the 2011 design value (i.e.,
the average of the 4th high values in
2009, 2010, and 2011) were conducive
to ozone formation. The State’s analysis
noted that the summer of 2009 was well
below normal for average temperatures,
but highlighted that data from Western
Michigan Regional Airport national
weather service site showed that a
number of days in summer of 2009 were
conducive to ozone formation. Overall,
the state identified 25 days between
May and September of 2009 that it
considered conducive to ozone
formation based on the criteria that the
temperature reached 80 degrees
Fahrenheit or greater, no precipitation
occurred, and the daily average wind
speed was less than 5 miles per hour. In
the EPA’s review, we find the State did
not sufficiently demonstrate that all
years within the alternative base period
were conducive to ozone formation. As
the State noted, the summer of 2009 was
abnormally cool in Michigan. While the
State also analyzed local meteorological
data (temperature, precipitation, wind
speed) near the Allegan, Michigan
monitor to identify 25 days that it
considered conducive to ozone
formation based on surface
temperatures, wind speed and
precipitation, the State did not provide
any technical analysis to demonstrate a
statistically significant relationship
between high ozone concentrations at
the Allegan receptor and the
temperature, precipitation, and wind
speed criteria used in the submittal to
define ozone conducive conditions for
this receptor. In addition, the State’s
evaluation did not discuss or consider
how other meteorological factors
identified in the October 2018
memorandum such as humidity, solar
radiation, vertical mixing, and/or other
meteorological indicators such as
cooling-degree days confirm whether
conditions affecting the monitor may
have been conducive to ozone formation
in 2009. The supplemental information
provided in the October 2018
memorandum, which included
temperature anomalies by state and
region of the U.S. and annual state-wide
average June–August temperature
rankings, clearly highlight that the
summer of 2009 was abnormally cool in
Michigan and the Great Lakes Region.
Therefore, the EPA finds that not all
years within the alternative base period
used by the State (i.e., 2009–2011) were
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conducive to ozone formation,
especially given the abnormally cold
temperatures seen in the summer of
2009. Accordingly, in view of the
guidance included in the October 2020
memorandum, it was not appropriate for
the state to have eliminated the Allegan,
Michigan receptor as a maintenance
receptor at Step 1 of the 4-step interstate
transport framework on this basis.
Further, the MoDNR’s attempt to
eliminate this receptor on the basis of
this analysis did not provide any basis
to eliminate the other receptors to
which the EPA’s modeling suggested the
state was linked. The EPA’s most recent
modeling, discussed further in section
III.A.3, confirms that the existence of
several receptors to which the state is
linked. The EPA therefore proposes to
proceed to evaluate the submittal at
Step 2.
2. Evaluation of Information Provided
by the State Regarding Step 2
As an initial matter, the EPA disagrees
with the arguments made by MoDNR
based on the ostensible ‘‘causation’’ of
the projected attainment and
maintenance problems at the receptors
in Brazoria County and Harris County in
Texas. While it is correct that impacts
from various sources, such as in-state
contributions, background ozone
concentrations, and international
emissions, are often themselves
significant contributors to attainment
and maintenance problems at receptors
for the 2015 ozone NAAQS, this does
not address the question of whether
there are also interstate transport
impacts from emissions sources or
activities in Missouri that significantly
contribute to nonattainment, or interfere
with maintenance, in any other state.
This question is not one of causation,
but rather of whether there is significant
contribution as contemplated in CAA
section 110(a)(2)(D)(i)(I). The EPA’s 4step interstate transport framework is
intended to evaluate whether there are
emissions that the State must address in
its SIP to meet this requirement for
purposes of the 2015 ozone NAAQS.
The State also utilized a 1 ppb
threshold at Step 2 for the receptors in
Wayne Michigan, Milwaukee,
Wisconsin and both Texas receptors to
evaluate whether the state was ‘‘linked’’
to a projected downwind nonattainment
or maintenance receptor. As discussed
in the EPA’s August 2018
memorandum, with appropriate
additional analysis it may be reasonable
for states to use a 1 ppb contribution
threshold, instead of the 1 percent of the
NAAQS threshold for the purposes of
identifying linkages to appropriate
downwind receptors. In some cases,
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MoDNR argued for application of the
alternative 1 ppb threshold, by
presenting the different numerical
percentages of downwind impacts that
the respective thresholds would result
in, and then asserting that the
percentages of upwind contribution
captured from the 1 ppb threshold
would be sufficiently substantial to
justify its use for Missouri.
For the Wayne, Michigan receptor,
MoDNR observed that application of a 1
ppb threshold would capture 61.8
percent of total upwind state
contributions, and that the contribution
captured by the 1 ppb threshold would
constitute 92.2 percent of the total
contribution that would be captured by
application of the 0.70 ppb threshold.
The State thus argued that use of a 1
ppb threshold instead of a 1% of the
NAAQS threshold will capture a
substantial amount of upwind states’
contribution to the ozone concentrations
at this site. Using this alternative
threshold, MoDNR stated that the
projected Missouri contribution to the
Wayne, Michigan receptor is 0.92 ppb,
and thus less than 1 ppb. MoDNR made
a comparable argument for the
Milwaukee, Wisconsin receptor (79.4
percent of the total contribution from all
upwind states and that the contribution
captured by the 1 ppb threshold is 83
percent of the amount captured by the
0.70 ppb threshold). For the receptors in
Brazoria County and Harris County,
Texas, the MoDNR did not provide any
additional analyses to determine the
appropriateness of the application of the
1 ppb threshold at either of these
receptors, and simply referred to the
August 2018 memorandum as evidence
to support the use of a 1 ppb threshold
at these receptors. Rather than a
quantitative comparison, MoDNR made
qualitative statements to the effect that
a 1 ppb threshold would be appropriate
given other considerations, such as the
impacts of local or international
sources.
However, the EPA’s memorandum did
not indicate that this type of
information alone was determinative of
whether an alternative threshold was in
fact appropriate to justify use of a
threshold in lieu of the 0.70 ppb level.
Rather, the EPA determined that by
capturing a percentage of upwind state
emissions comparable to the amount
captured at 1 percent, the alternative
threshold may be appropriate,
indicating that a more determinative
conclusion of appropriateness would
require further analysis. The MoDNR
did not provide any further technical
justification to make that determination.
The EPA notes that in each case, the
use of the alternative 1 ppb threshold
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would have the result of reducing the
amount of cumulative upwind state
emissions that would be captured.
While the EPA does not, in this action,
approve of the state’s application of the
1 ppb threshold, because the state has
linkages greater than 1 ppb to projected
downwind nonattainment or
maintenance receptors, the state’s use of
this alternative threshold at Step 2 of
the 4-step interstate framework would
not alter our review and proposed
disapproval of this SIP submittal.
The EPA here shares further
evaluation of its experience since the
issuance of the August 2018
memorandum regarding use of
alternative thresholds at Step 2. This
experience leads the Agency to now
believe it may not be appropriate to
continue to attempt to recognize
alternative contribution thresholds at
Step 2. The August 2018 memorandum
stated that ‘‘it may be reasonable and
appropriate’’ for states to rely on an
alternative threshold of 1 ppb at Step
2.31 However, the EPA also indicated
that ‘‘air agencies should consider
whether the recommendations in this
guidance are appropriate for each
situation.’’ Following receipt and review
of 49 good neighbor SIP submittals for
the 2015 8-hour ozone NAAQS, the
EPA’s experience has been that nearly
every state that attempted to rely on a
1 ppb threshold did not provide
sufficient information and analysis to
support a determination that an
alternative threshold was reasonable or
appropriate for that state.
For instance, in nearly all submittals,
the states did not provide the EPA with
analysis specific to their state or the
receptors to which its emissions are
potentially linked. In one case, the
proposed approval of Iowa’s SIP
submittal, the EPA expended its own
resources to attempt to supplement the
information submitted by the state, in
order to more thoroughly evaluate the
state-specific circumstances that could
support approval.32 It was at the EPA’s
sole discretion to perform this analysis
in support of the state’s submittal, and
the Agency is not obligated to conduct
supplemental analysis to fill the gaps
whenever it believes a state’s analysis is
insufficient. The Agency no longer
intends to undertake supplemental
analysis of SIP submittals with respect
2018 memo at 4.
Plan Approval; Iowa; Infrastructure State
Implementation Plan Requirements for the 2015
Ozone National Ambient Air Quality Standard, 85
FR 12232 (March 2, 2020). The Agency received
adverse comment on this proposed approval and
has not taken final action with respect to this
proposal.
to alternative thresholds at Step 2 for
purposes of the 2015 ozone NAAQS.
Furthermore, the EPA’s experience
since 2018 is that allowing for
alternative Step 2 thresholds may be
impractical or otherwise inadvisable for
a number of additional policy reasons.
For a regional air pollutant such as
ozone, consistency in requirements and
expectations across all states is
essential. Based on its review of
submittals to-date and after further
consideration of the policy implications
of attempting to recognize an alternative
Step 2 threshold for certain states, the
Agency now believes the attempted use
of different thresholds at Step 2 with
respect to the 2015 ozone NAAQS raises
substantial policy, consistency, and
practical implementation concerns.33
The availability of different thresholds
at Step 2 has the potential to result in
inconsistent application of good
neighbor obligations based solely on the
strength of a state’s SIP submittal at Step
2 of the 4-step interstate transport
framework. From the perspective of
ensuring effective regional
implementation of good neighbor
obligations, the more important analysis
is the evaluation of the emissions
reductions needed, if any, to address a
state’s significant contribution after
consideration of a multifactor analysis
at Step 3, including a detailed
evaluation that considers air quality
factors and cost. Where alternative
thresholds for purposes of Step 2 may
be ‘‘similar’’ in terms of capturing the
relative amount of upwind contribution
(as described in the August 2018
memorandum), nonetheless, use of an
alternative threshold could allow
certain states to avoid further evaluation
of potential emission controls while
other states must proceed to a Step 3
analysis. This can create significant
equity and consistency problems among
states.
Further, it is not clear that national
ozone transport policy is best served by
allowing for less stringent thresholds at
Step 2. The EPA recognized in the
August 2018 memo that there was some
similarity in the amount of total upwind
contribution captured (on a nationwide
basis) between 1percent and 1 ppb.
However, the EPA notes that while this
may be true in some sense, that is
hardly a compelling basis to move to a
1 ppb threshold. Indeed, the 1 ppb
threshold has the disadvantage of losing
31 August
32 Air
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33 We note that Congress has placed on the EPA
a general obligation to ensure the requirements of
the CAA are implemented consistently across states
and regions. See CAA section 301(a)(2). Where the
management and regulation of interstate pollution
levels spanning many states is at stake, consistency
in application of CAA requirements is paramount.
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a certain amount of total upwind
contribution for further evaluation at
Step 3 (e.g., roughly seven percent of
total upwind state contribution was lost
according to the modeling underlying
the August 2018 memorandum; 34 in the
EPA’s updated modeling, the amount
lost is five percent). Considering the
core statutory objective of ensuring
elimination of all significant
contribution to nonattainment or
interference of the NAAQS in other
states and the broad, regional nature of
the collective contribution problem with
respect to ozone, there does not appear
to be a compelling policy imperative in
allowing some states to use a 1 ppb
threshold while others rely on a 1
percent of NAAQS threshold.
Consistency with past interstate
transport actions such as CSAPR, and
the CSAPR Update and Revised CSAPR
Update rulemakings (which used a Step
2 threshold of 1 percent of the NAAQS
for two less stringent ozone NAAQS), is
also important. Continuing to use a 1
percent of NAAQS approach ensures
that as the NAAQS are revised and
made more stringent, an appropriate
increase in stringency at Step 2 occurs,
so as to ensure an appropriately larger
amount of total upwind-state
contribution is captured for purposes of
fully addressing interstate transport.
Accord 76 FR 48237–38.
Therefore, notwithstanding the
August 2018 memorandum’s
recognition of the potential viability of
alternative Step 2 thresholds, and in
particular, a potentially applicable 1
ppb threshold, the EPA’s experience
since the issuance of that memo has
revealed substantial programmatic and
policy difficulties in attempting to
implement this approach. Nonetheless,
the EPA is not, at this time, rescinding
the August 2018 memorandum. The
EPA invites comment on this broader
discussion of issues associated with
alternative thresholds at Step 2.
Depending on comment and further
evaluation of this issue, the EPA may
determine to rescind the August 2018
memorandum in the future.
MoDNR used two arguments at Step
2 for excluding the nonattainment
receptor in Sheboygan, Wisconsin,
(Monitor ID: 551170006). First, the State
utilized a 2 ppb threshold at Step 2 to
identify whether the state was ‘‘linked’’
to this receptor. Second, the state argued
that any reductions from Missouri
would have a de minimis or minimal
effect on air quality improvements at
this receptor due to the larger impacts
from other states such as Wisconsin,
34 See
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Illinois and Indiana. The EPA discusses
both of these arguments in this section.
In its analysis, the state argued that
because a 2 ppb threshold would
capture 68.2% of cumulative upwind
state contributions at the Sheboygan
receptor, similar to the ‘‘approximately
70 percent of total upwind
contribution’’ captured on average
nationwide at the 1 ppb threshold the
EPA identified in the August 2018
memorandum, a 2 ppb threshold is
appropriate to use at this receptor.
While the EPA had determined that an
alternative threshold that would capture
a sufficient percentage of upwind state
emissions comparable to the amount
that would be captured at the level of 1
percent of the NAAQS may be
appropriate, the Agency also indicated
that more analysis would be needed to
reach a determinative conclusion of
appropriateness. As explained with
respect to the alternative 1 ppb
threshold that MoDNR sought to use for
the for the receptors in Wayne
Michigan, Milwaukee, Wisconsin and
both Texas receptors, it did not provide
any further technical justification to
make the determination.
As explained with respect to the
potential use of an alternative 1 ppb
threshold, the EPA’s experience since
the issuance of the 2018 memorandum
discussing the issue has revealed
substantial programmatic and policy
difficulties in attempting to implement
this approach even for a 1 ppb
threshold. At no point did the EPA
suggest that a 2 ppb threshold might be
appropriate for this purpose under any
circumstances. Such a threshold would
be higher than the threshold that the
EPA has historically used in interstate
transport rules that courts have
approved (i.e., 1 percent of the NAAQS
at issue), or that the EPA has considered
even potentially appropriate if it were to
achieve functionally the same air
quality impacts (i.e., 1 ppb).
The second argument that the state
used to exclude the Sheboygan,
Wisconsin receptor in Step 2 was
related to emissions from other states.
The state argued that the primary
contributors to the projected ozone
concentrations in Sheboygan are the
upwind states of Illinois and Indiana
and the home state itself, Wisconsin.
The EPA’s 2018 modeling showed these
states would contribute a combined
31.93 ppb in 2023 to the Sheboygan
receptor. However, the state’s reasoning
related to Indiana, Illinois and
Wisconsin emissions is inapplicable to
the requirements of CAA section
110(a)(2)(D)(i)(I). The good neighbor
provision requires states and the EPA to
address interstate transport of air
pollution that contributes to downwind
states’ ability to attain and maintain
NAAQS. Whether emissions from other
states also contribute to the same
downwind air quality issue is irrelevant
in assessing whether a downwind state
has an air quality problem, or whether
the upwind state at issue state is
significantly contributing to that
problem. The Ozone NAAQS
nonattainment and maintenance
problems that result from interstate
transport are typically the result of
cumulative impacts from multiple
states. States are not obligated under
CAA section 110(a)(2)(D)(i)(I) to reduce
emissions only if doing so would be
sufficient in isolation to resolve all
downwind nonattainment or
maintenance problems. Rather, each
state is obligated to eliminate its own
‘‘significant contribution’’ or
‘‘interference’’ with the ability of other
states to attain or maintain the NAAQS.
Indeed, the D.C. Circuit in Wisconsin
specifically rejected petitioner
arguments suggesting that upwind states
should be excused from good neighbor
obligations on the basis that some other
source of emissions (whether
international or another upwind state)
could be considered the ‘‘but-for’’ cause
of downwind air quality problem. 938
F.3d 303 at 323–324. The court viewed
petitioners’ arguments as essentially an
argument ‘‘that an upwind State
‘contributes significantly’ to downwind
nonattainment only when its emissions
are the sole cause of downwind
nonattainment.’’ 938 F.3d 303 at 324.
The court explained that ‘‘an upwind
State can ‘contribute’ to downwind
nonattainment even if its emissions are
not the but-for cause.’’ Id. at 324–325.
See also Catawba County v. EPA, 571
F.3d 20, 39 (D.C. Cir. 2009) (rejecting
the argument ‘‘that ‘significantly
contribute’ unambiguously means
‘strictly cause’ ’’ because there is ‘‘no
reason why the statute precludes EPA
from determining that [an] addition of
[pollutant] into the atmosphere is
significant even though a nearby
county’s nonattainment problem would
still persist in its absence’’); Miss.
Comm’n on Envtl. Quality v. EPA, 790
35 Because the EPA finds that the MoDNR
submittal’s arguments with respect to its linkages in
the modeling it relied on are not sufficient or
technically justified to conclude the state is not
linked to downwind receptors, the EPA can also
conclude that the same arguments would not be
meritorious even if applied with respect to the
receptor linkages the EPA finds in its more recent
2023 modeling using the 2016v2 emissions
platform.
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F.3d 138, 163 n.12 (D.C. Cir. 2015)
(observing that the argument that ‘‘there
likely would have been no violation at
all . . . if it were not for the emissions
resulting from [another source]’’ is
‘‘merely a rephrasing of the but-for
causation rule that we rejected in
Catawba County.’’). Therefore, a state is
not excused from eliminating its
significant contribution on the basis that
other states’ emissions also contribute
some amount of pollution to the same
receptors to which the state is linked.
As a result, Step 3 analysis of the 4-Step
Interstate Transport Framework is
necessary.
Thus, the EPA proposes that
MoDNR’s submittal did not adequately
justify the use of an alternative
threshold or otherwise establish that it
should not be considered linked at Step
2. The EPA proposes to apply the 1
percent of NAAQS threshold, consistent
with the discussion in this subsection.
Under the proposed 1 percent threshold,
both in the modeling available to the
state at the time it made its submittal,
and under the newly available 2023
modeling discussed below, Missouri is
linked to downwind nonattainment and
maintenance receptors.35
3. Results of the EPA’s Step 1 and Step
2 Modeling and Findings for Missouri
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 EPA examined these data
to determine if emissions in Missouri
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
in this most recent round of modeling.
As shown in Table 2, the data indicate
that in 2023, emissions from sources in
Missouri contribute greater than 1
percent of the NAAQS to nonattainment
or maintenance-only receptors in Racine
County and Kenosha County,
Wisconsin, and Cook County, Illinois.36
Therefore, based on the EPA’s
evaluation of the information submitted
by MoDNR, and based on the EPA’s
most recent modeling results for 2023,
the EPA proposes to find that Missouri
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.
36 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.
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TABLE 2—MISSOURI LINKAGE RESULTS BASED ON THE EPA UPDATED 2023 MODELING
Receptor ID
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550590025
550590019
170317002
551010020
..........................
..........................
..........................
..........................
Location
Nonattainment/maintenance
Kenosha, Wisconsin .........
Kenosha, Wisconsin .........
Cook, Illinois ......................
Racine, Wisconsin ............
Maintenance ..........................
Nonattainment .......................
Maintenance ..........................
Nonattainment .......................
4. 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).
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.
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2023 Average
design value
(ppb)
MoDNR did not conduct such an
analysis in its SIP submission, as a
result of its conclusions pursuant to
Step 1 and Step 2 of its analysis with
respect to the six receptors that the EPA
previously identified. As explained in
connection with the evaluation of
MoDNR’s Step 1 and Step 2 analyses,
the EPA disagrees with those analyses
and accordingly the State should have
evaluated effectively which emissions
in the State should be deemed
‘‘significant’’ and therefore prohibited,
in its SIP submission. We therefore
propose that MoDNR was required to
analyze emissions from the sources and
other emissions activity from within the
state to determine whether its
contributions were significant, and we
propose to disapprove its submission
because MoDNR failed to do so.
5. 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. As
mentioned previously, Missouri’s SIP
submission did not contain an
evaluation of additional emission
control opportunities (or establish that
no additional controls are required),
thus, no information was provided at
step 4. As a result, the EPA proposes to
disapprove Missouri’ submittal on the
separate, additional basis that the State
has not developed permanent and
enforceable emissions reductions
necessary to meet the obligations of
CAA section 110(a)(2)(d)(i)(I).
6. Conclusion
Based on the EPA’s evaluation of the
MoDNR’s SIP submission, the EPA is
proposing to find that the MoDNR’s
June 10, 2019 SIP submission
addressing CAA section
110(a)(2)(D)(i)(I) does not meet the
State’s interstate transport obligations,
because it fails to contain the necessary
provisions to eliminate emissions that
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Fmt 4702
Sfmt 4702
2023 Maximum
design value
(ppb)
MO contribution
(ppb)
72.3
73.7
73.0
73.2
1.66
1.08
0.94
0.92
69.2
72.8
70.1
71.3
will contribute significantly to
nonattainment or interfere with
maintenance of the 2015 8-hour ozone
NAAQS in any other state.
IV. Proposed Action
We are proposing to disapprove the
MoDNR’s June 10, 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
Missouri 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 SIP
that meets these requirements.
Disapproval does not start a mandatory
sanctions clock for Missouri.
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 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
E:\FR\FM\22FEP1.SGM
22FEP1
Federal Register / Vol. 87, No. 35 / Tuesday, February 22, 2022 / Proposed Rules
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
lotter on DSK11XQN23PROD with PROPOSALS1
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
action will not have potential
disproportionately high and adverse
human health or environmental effects
on minority, low-income or indigenous
populations. This action merely
VerDate Sep<11>2014
17:03 Feb 18, 2022
Jkt 256001
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).37
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 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 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
37 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.
PO 00000
Frm 00091
Fmt 4702
Sfmt 4702
9545
has selected a nationally uniform
analytic year (2023) for this analysis and
is applying a nationally uniform
approach to nonattainment and
maintenance receptors and a nationally
uniform approach to contribution
threshold analysis.38 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).39
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 9, 2022.
Meghan A. McCollister,
Regional Administrator, Region 7.
[FR Doc. 2022–03183 Filed 2–18–22; 8:45 am]
BILLING CODE 6560–50–P
ENVIRONMENTAL PROTECTION
AGENCY
40 CFR Part 52
[EPA–R04–OAR–2021–0841; EPA–HQ–
OAR–2021–0663; FRL–9421–01–R4]
Air Plan Disapproval; AL, MS, TN;
Interstate Transport Requirements for
the 2015 8-Hour Ozone National
Ambient Air Quality Standards
Environmental Protection
Agency (EPA).
ACTION: Proposed rule and withdrawal
of proposed rule.
AGENCY:
Pursuant to the Federal Clean
Air Act (CAA or the Act), the
Environmental Protection Agency (EPA
or Agency) is proposing to disapprove
State Implementation Plan (SIP)
submittals from Alabama, Mississippi,
SUMMARY:
38 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.
39 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.
E:\FR\FM\22FEP1.SGM
22FEP1
]]>Agencies
[Federal Register Volume 87, Number 35 (Tuesday, February 22, 2022)]
[Proposed Rules]
[Pages 9533-9545]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2022-03183]
-----------------------------------------------------------------------
ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 52
EPA-R07-OAR-2021-0851; EPA-HQ-OAR-2021-0663; FRL-9425-01-R7]
Air Plan Disapproval; Missouri Interstate Transport of Air
Pollution for the 2015 8-Hour Ozone National Ambient Air Quality
Standards
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 Missouri regarding
interstate transport for the 2015 8-hour ozone national ambient air
quality standards (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 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-R07-OAR-
2021-0851, by any of the following methods: Federal eRulemaking Portal
at https://
[[Page 9534]]
www.regulations.gov following the online nstructions for submitting
comments or via email to [email protected]. Include Docket ID No.
EPA-R07-OAR-2021-0851 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-2021-0851, 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 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-2021-0851
and EPA-HQ-OAR-2021-0663. Docket No. EPA-R07-OAR-2021-0851 contains
information specific to Missouri, 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-
0851. 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-
2021-0851, 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.
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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[[Page 9535]]
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
The EPA has released several documents containing 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 (DVs) 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 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\ 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 the 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-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 DVs 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\ See 85 FR 68964, 68981. 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 Revised CSAPR Update final rule, 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
[[Page 9536]]
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. with the
2016 base year and 2023 future year emissions developed as part of the
2016v2 emissions platform.\19\ The EPA now proposes to rely on modeling
based on the updated and newly available 2016v2 air quality modeling in
evaluating these submissions with respect to Steps 1 and 2 of the 4-
step interstate transport framework. 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 included in the docket for this
proposal contain additional detail on the modeling performed using the
2016v2 emissions. In this document, the EPA is accepting public comment
on this updated 2023 modeling, which uses a 2016 emissions platform.
Details on the air quality modeling and the methods for projecting
design values and determining contributions in 2023 are described in
the Air Quality Modeling TSD for 2015 Ozone NAAQS Transport SIP
Proposed Actions. Comments on the EPA's air quality modeling should be
submitted in the Regional docket for this action, docket ID No. EPA-
R07-OAR-2021-0851. Comments are not being accepted in docket 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 Multi-Jurisdictional
Organizations (MJOs) to evaluate downwind air quality problems and
contributions as part of their submissions. In section III we evaluate
how Missouri 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 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, the 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
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 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, 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 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
[[Page 9537]]
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-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 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 896, 910-11 (D.C. Cir.
2008) (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\
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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).
---------------------------------------------------------------------------
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 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.
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\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. Consistent with the methodology described for
nonattainment, those sites that are
[[Page 9538]]
currently measuring ozone concentrations below the level of the
applicable NAAQS, but that are projected to be nonattainment based on
the average or maximum design values, are identified as maintenance-
only receptors.
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, portion of the nonattainment problems from anthropogenic
sources in the U.S. results from the combined impact of relatively
small contributions from many upwind states, along with contributions
from in-state sources and, in some cases, substantially larger
contributions from a subset of particular upwind states. 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\
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\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.
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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. SIP Submission Addressing Interstate Transport of Air Pollution for
the 2015 8-Hour Ozone NAAQS
On June 10, 2019, the Missouri Department of Natural Resources' Air
Pollution Control Program (MoDNR)
[[Page 9539]]
made a SIP submission to address interstate transport of air pollution
for the 2015 8-hour ozone NAAQS. MoDNR's good neighbor SIP submission
for the 2015 ozone NAAQS relied on the EPA's four-step approach and
corresponding memoranda for determining obligations for upwind states
to limit transported air pollution to downwind states. The State
concluded that emissions from sources or emissions activity in Missouri
will not contribute significantly to nonattainment or interfere with
maintenance of the 2015 ozone NAAQS in any downwind states.
In its analysis, the state relied on the EPA's modeling released
with the March 2018 memorandum to identify nonattainment and
maintenance receptors in 2023 (Step 1). The State also relied on the
EPA's modeling from the March 2018 memorandum to identify which
monitors were then linked to emissions from Missouri. In its
submission, the MoDNR identified all of the nonattainment and
maintenance receptors to which Missouri was projected to contribute
more than 0.70 ppb to the 2023 DV. Table 1 provides information on the
six nonattainment and maintenance receptors identified by the MoDNR.
Table 1--2023 Average and Maximum Design Values at Downwind Receptors With Missouri Contributions Larger Than
0.70 ppb
----------------------------------------------------------------------------------------------------------------
Missouri
Site (monitor, county, state) 2023 Average 2023 Maximum contribution Comments
DV (ppb) DV (ppb) (ppb)
----------------------------------------------------------------------------------------------------------------
260050003, Allegan, MI........ 69.0 71.7 2.61 Maintenance receptor.
261630019, Wayne, MI.......... 69.0 71.0 0.92 Maintenance receptor.
484392003, Brazoria, TX....... 74.0 74.9 0.88 Nonattainment receptor.
482011039, Harris, TX......... 71.8 73.5 0.88 Nonattainment receptor.
550790085 Milwaukee, WI....... 71.2 73.0 0.93 Nonattainment receptor.
551170006, Sheboygan, WI...... 72.8 75.1 1.37 Nonattainment receptor.
----------------------------------------------------------------------------------------------------------------
The state analyzed each of the six receptors in Table 1 using
information in the EPA's 2018 guidance memoranda described above. For
the two receptors in Texas, the state observed that the total upwind
state contribution is approximately 13 ppb to both of these Texas
receptors and that Texas' in-state contribution to these two receptors
is 26 ppb to the Brazoria County receptor and 22.6 ppb to the Harris
County receptor. The MoDNR combined the contributions from initial/
boundary conditions with the contribution from biogenic emissions to
show that the contribution from these two categories is over 52 ppb, at
these two receptors. Based on this information, the MoDNR claimed that
the ozone problems at these two receptors are not caused by upwind U.S.
anthropogenic emissions from other states, but rather that in-state
contributions, natural ozone concentrations, and international
emissions are the likely significant contributors to the problem at
these two sites.
The MoDNR also noted that its contribution to the projected 2023
ozone DV at the two Texas receptors is 0.88 ppb. The MoDNR then
referenced statements in the EPA's August 2018 memorandum on the use of
alternative thresholds that a 1 ppb threshold would generally capture a
substantial amount of transported contribution from upwind states to
the downwind monitors. The MoDNR concluded that 1 ppb is, therefore, an
appropriate alternative screening threshold for evaluating whether
emissions in their state are linked to the ozone problems at these two
receptors. Based on this alternative threshold, the State determined
that it will not contribute significantly to these nonattainment
receptors in 2023. The MoDNR then concluded that its SIP sufficiently
addresses the good neighbor obligation for the 2015 ozone NAAQS with
respect to these two Texas receptors based only on its Step 2 weight of
evidence analysis.
For the Milwaukee, Wisconsin receptor, the MoDNR noted that its
projected contribution to this receptor is 0.93 ppb, and thus less than
1 ppb. The State observed that the 1 ppb threshold would capture 79.4
percent of the total contribution from all upwind states and that the
contribution captured by the 1 ppb threshold is 83 percent of the
amount captured by the 0.70 ppb threshold at this receptor. The state
asserted that the 1 ppb threshold would capture a substantial amount of
total upwind states' contribution to ozone concentrations at this
receptor, which will lead to meaningful emission reductions to ensure
attainment of the NAAQS at this monitor in 2023. Therefore, the MoDNR
relied on a 1 ppb threshold to conclude that its existing SIP
sufficiently addresses the good neighbor obligation for the 2015 ozone
NAAQS with respect to this receptor.
For the Wayne, Michigan site, the state observed that the 1 ppb
threshold captures 61.8 percent of total upwind state contributions and
the contribution captured by the 1 ppb threshold would constitute 92.2
percent of the total contribution that would be captured by the 0.70
ppb threshold. The state asserted that the 1 ppb threshold will capture
a substantial amount of upwind states' contribution to the ozone
concentrations at this site, which will lead to meaningful emission
reductions that will help ensure attainment of the NAAQS at this
receptor in 2023. The MoDNR noted that its projected contribution to
the Wayne, Michigan receptor is 0.92 ppb, and thus less than 1 ppb.
Therefore, the MoDNR concluded that its existing SIP sufficiently
addresses the good neighbor obligation for the 2015 ozone NAAQS with
respect to this receptor based only on this Step 2 weight of evidence
analysis.
For the Sheboygan, Wisconsin site, the State observed that the 1
ppb threshold would capture 79.4 percent of the total upwind
contributions and that a 2 ppb threshold would capture 68.2 percent of
the total upwind state contributions. The State also observed that an
alternative 2 ppb threshold would capture 85.9 percent of the upwind
state contributions captured under a 1 ppb threshold. Using these data,
the MoDNR asserted that a 2 ppb threshold is appropriate because it
would capture nearly 70 percent of the total upwind state contributions
and thus would result in meaningful emission reductions that will help
to ensure attainment of the NAAQS at the site by 2023. The state also
asserted that the primary contributors to the projected ozone
concentrations at the monitor in Sheboygan include emissions from
Illinois, Indiana, and Wisconsin. The MoDNR cited the EPA modeling
projecting that emissions from these states would contribute a
[[Page 9540]]
combined 31.93 ppb in 2023 to the Sheboygan receptor.
For the Sheboygan receptor, the MoDNR also pointed to the Lake
Michigan Air Director's Consortium's (LADCO's) interstate transport
modeling results for the 2015 ozone NAAQS. The State noted that LADCO's
analysis also indicates that the ozone levels at the Wisconsin
shoreline of Lake Michigan are heavily affected by the emissions from
Illinois, Indiana, and Wisconsin.\30\
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\30\ Interstate Transport Modeling for the 2015 Ozone National
Ambient Air Quality Standard, the technical support document (TSD),
https://www.ladco.org/wp-content/uploads/Documents/Reports/TSDs/O3/LADCO_2015O3iSIP_TSD_13Aug2018.pdf.
---------------------------------------------------------------------------
The MoDNR further pointed out that the other monitoring site in
Sheboygan County (551170009), which is a few miles further inland than
the Sheboygan nonattainment receptor, has no projected problems with
attaining and maintaining compliance with the 2015 ozone NAAQS. The
MoDNR concluded that the nonattainment receptor in Sheboygan is heavily
influenced by local transport emissions and lake breeze effects over
Lake Michigan. The State asserted that use of a 2 ppb threshold would
capture a substantial amount of upwind states' contribution to the
ozone concentrations at this site, which will lead to meaningful
emission reductions that will help ensure attainment of the NAAQS at
this monitor in 2023. The MoDNR noted that its projected contribution
to the Sheboygan, Wisconsin receptor is 1.37 ppb, which is less than 2
ppb. Therefore, the MoDNR concluded that its existing SIP sufficiently
addresses the good neighbor obligation for the 2015 ozone NAAQS with
respect to the Sheboygan receptor based only on this Step 2 weight of
evidence analysis.
For the Allegan, Michigan receptor, the MoDNR used an analysis
based on information in the EPA's October 2018 memorandum on
alternative approaches for identifying maintenance receptors to claim
that the Allegan monitoring site will not be a receptor in 2023.
Specifically, rather than rely upon the EPA's projected 2023 maximum
design value for identifying maintenance receptors, the state used an
alternative approach that included projected 2023 ozone concentrations
based on a 2-year base period (2010-2011), a 3-year base period (2009-
2011) and a 4-year base period (2009-2012) to demonstrate that the
Allegan monitoring site would attain the standard by 2023. To support
the use of these alternative base periods, the State provided an
analysis for the three consideration outlined in the August 2018
memorandum: (i) Meteorological conditions in the area of the monitoring
site were conducive to ozone formation during the alternative base
period design value used for projections; (ii) ozone concentrations
have been trending downward at the site since 2011 (and ozone precursor
emissions of NOX and VOCs have also decreased); and (iii)
emissions are expected to continue to decline in the upwind and
downwind states out to the attainment date of the site. The MoDNR noted
that ozone concentrations during the summer of 2009 were well below
normal for the state of Michigan despite having a large number of days
during the ozone season where they claim that meteorology was conducive
to ozone formation. The MoDNR also noted that the summer of 2012 was
among the most ozone conducive summers across the entire Midwestern
portion of the country. MoDNR suggested that the variation in the
degree of ozone conducive meteorology between 2009 and 2012 would
counterbalance in the alternative baseline period.
The State provided an analysis showing ozone concentrations
trending down since 2012 at the Allegan monitor. The State also
provided the total statewide anthropogenic NOX and VOC
emissions (ozone precursors) in Michigan, Missouri, and two neighboring
states that are upwind of the Allegan monitor during 2011 and 2017
(i.e., Illinois and Indiana), which showed that emissions in all four
of these states went down during this time period.
The MoDNR concluded that the Allegan receptor meets all the
criteria listed in the EPA October memorandum relating to alternative
methods for identifying maintenance receptors. Based on this analysis,
the MoDNR asserted that the Allegan Michigan monitor should not be a
maintenance receptor for purposes of the 2015 ozone NAAQS. Therefore,
the State found that the Missouri' existing SIP fully addresses the CAA
good neighbor obligation with respect to the Allegan, Michigan
receptor.
Based on the analysis above, the MoDNR concluded that its current
SIP adequately addresses the state's obligation under CAA section
110(a)(2)(D)(i)(I) (the good neighbor provision) with respect to the
2015 ozone NAAQS. The MoDNR stated that it has demonstrated that its
SIP submittal ensures that emissions in Missouri will not significantly
contribute to nonattainment or interfere with maintenance of the 2015
ozone NAAQS in any downwind state. Based on this conclusion, the MoDNR
concluded its analysis at Step 2 of the 4-step interstate transport
framework and provided no analysis for steps 3 or 4.
III. EPA Evaluation
The EPA is proposing to find that the June 10, 2019, SIP submission
from the MoDNR does not meet the State's obligations with respect to
prohibiting emissions that contribute significantly to nonattainment or
interfere with maintenance of the 2015 8-hour ozone NAAQS in any other
state based on the EPA's evaluation of the SIP submission using the 4-
step interstate transport framework, and the EPA is therefore proposing
to disapprove Missouri's submission.
A. Missouri
1. Evaluation of Information Provided by the MoDNR Regarding Step 1
At Step 1 of the 4-Step interstate transport framework, the MoDNR
relied on the EPA modeling released in the March 2018 memorandum to
identify nonattainment and maintenance receptors in 2023. As correctly
noted in the MoDNR SIP submittal, the EPA's prior analysis indicated
that the State was linked to six nonattainment and/or maintenance
receptors in three downwind states in 2023 (identified in Table 1 of
this action). In its October 2018 memorandum on alternative maintenance
receptors, the EPA suggested that States could provide meteorological
data, among other data, to support potential alternative methodologies
or flexibilities to identify maintenance receptors. The MoDNR utilized
this flexibility to eliminate the Allegan, Michigan maintenance
receptor (monitor ID 260050003) based on the use of alternative base
year periods. The State considered three alternative base periods as a
basis for projecting design values in 2023. These based periods include
(1) a 2-year base period using 4th high ozone concentrations in 2010
and 2011, (2) a 3-year base year period from 2009-2011, and (3) a 4-
year base year period from 2009-2012. As an initial matter, design
values, by definition are based on the average of the 4th highest
maximum daily 8-hour ozone concentration in three consecutive years.
The ``pseudo'' design values calculated by the State using 2 years of
data, when data for the third year (i.e., 2009) were clearly available,
and using 4 years of data do not constitute alternative design values.
In this regard, the approach by the State using these two alternatives
runs counter to the approach identified in the October 2018 memorandum:
``. . . . EPA believes that a state may, in some
[[Page 9541]]
cases, use a design value from the base period that is not the maximum
design value.''
The State also provided information and analysis of meteorological
data to attempt to establish that all years that constitute the 2011
design value (i.e., the average of the 4th high values in 2009, 2010,
and 2011) were conducive to ozone formation. The State's analysis noted
that the summer of 2009 was well below normal for average temperatures,
but highlighted that data from Western Michigan Regional Airport
national weather service site showed that a number of days in summer of
2009 were conducive to ozone formation. Overall, the state identified
25 days between May and September of 2009 that it considered conducive
to ozone formation based on the criteria that the temperature reached
80 degrees Fahrenheit or greater, no precipitation occurred, and the
daily average wind speed was less than 5 miles per hour. In the EPA's
review, we find the State did not sufficiently demonstrate that all
years within the alternative base period were conducive to ozone
formation. As the State noted, the summer of 2009 was abnormally cool
in Michigan. While the State also analyzed local meteorological data
(temperature, precipitation, wind speed) near the Allegan, Michigan
monitor to identify 25 days that it considered conducive to ozone
formation based on surface temperatures, wind speed and precipitation,
the State did not provide any technical analysis to demonstrate a
statistically significant relationship between high ozone
concentrations at the Allegan receptor and the temperature,
precipitation, and wind speed criteria used in the submittal to define
ozone conducive conditions for this receptor. In addition, the State's
evaluation did not discuss or consider how other meteorological factors
identified in the October 2018 memorandum such as humidity, solar
radiation, vertical mixing, and/or other meteorological indicators such
as cooling-degree days confirm whether conditions affecting the monitor
may have been conducive to ozone formation in 2009. The supplemental
information provided in the October 2018 memorandum, which included
temperature anomalies by state and region of the U.S. and annual state-
wide average June-August temperature rankings, clearly highlight that
the summer of 2009 was abnormally cool in Michigan and the Great Lakes
Region. Therefore, the EPA finds that not all years within the
alternative base period used by the State (i.e., 2009-2011) were
conducive to ozone formation, especially given the abnormally cold
temperatures seen in the summer of 2009. Accordingly, in view of the
guidance included in the October 2020 memorandum, it was not
appropriate for the state to have eliminated the Allegan, Michigan
receptor as a maintenance receptor at Step 1 of the 4-step interstate
transport framework on this basis.
Further, the MoDNR's attempt to eliminate this receptor on the
basis of this analysis did not provide any basis to eliminate the other
receptors to which the EPA's modeling suggested the state was linked.
The EPA's most recent modeling, discussed further in section III.A.3,
confirms that the existence of several receptors to which the state is
linked. The EPA therefore proposes to proceed to evaluate the submittal
at Step 2.
2. Evaluation of Information Provided by the State Regarding Step 2
As an initial matter, the EPA disagrees with the arguments made by
MoDNR based on the ostensible ``causation'' of the projected attainment
and maintenance problems at the receptors in Brazoria County and Harris
County in Texas. While it is correct that impacts from various sources,
such as in-state contributions, background ozone concentrations, and
international emissions, are often themselves significant contributors
to attainment and maintenance problems at receptors for the 2015 ozone
NAAQS, this does not address the question of whether there are also
interstate transport impacts from emissions sources or activities in
Missouri that significantly contribute to nonattainment, or interfere
with maintenance, in any other state. This question is not one of
causation, but rather of whether there is significant contribution as
contemplated in CAA section 110(a)(2)(D)(i)(I). The EPA's 4-step
interstate transport framework is intended to evaluate whether there
are emissions that the State must address in its SIP to meet this
requirement for purposes of the 2015 ozone NAAQS.
The State also utilized a 1 ppb threshold at Step 2 for the
receptors in Wayne Michigan, Milwaukee, Wisconsin and both Texas
receptors to evaluate whether the state was ``linked'' to a projected
downwind nonattainment or maintenance receptor. As discussed in the
EPA's August 2018 memorandum, with appropriate additional analysis it
may be reasonable for states to use a 1 ppb contribution threshold,
instead of the 1 percent of the NAAQS threshold for the purposes of
identifying linkages to appropriate downwind receptors. In some cases,
MoDNR argued for application of the alternative 1 ppb threshold, by
presenting the different numerical percentages of downwind impacts that
the respective thresholds would result in, and then asserting that the
percentages of upwind contribution captured from the 1 ppb threshold
would be sufficiently substantial to justify its use for Missouri.
For the Wayne, Michigan receptor, MoDNR observed that application
of a 1 ppb threshold would capture 61.8 percent of total upwind state
contributions, and that the contribution captured by the 1 ppb
threshold would constitute 92.2 percent of the total contribution that
would be captured by application of the 0.70 ppb threshold. The State
thus argued that use of a 1 ppb threshold instead of a 1% of the NAAQS
threshold will capture a substantial amount of upwind states'
contribution to the ozone concentrations at this site. Using this
alternative threshold, MoDNR stated that the projected Missouri
contribution to the Wayne, Michigan receptor is 0.92 ppb, and thus less
than 1 ppb. MoDNR made a comparable argument for the Milwaukee,
Wisconsin receptor (79.4 percent of the total contribution from all
upwind states and that the contribution captured by the 1 ppb threshold
is 83 percent of the amount captured by the 0.70 ppb threshold). For
the receptors in Brazoria County and Harris County, Texas, the MoDNR
did not provide any additional analyses to determine the
appropriateness of the application of the 1 ppb threshold at either of
these receptors, and simply referred to the August 2018 memorandum as
evidence to support the use of a 1 ppb threshold at these receptors.
Rather than a quantitative comparison, MoDNR made qualitative
statements to the effect that a 1 ppb threshold would be appropriate
given other considerations, such as the impacts of local or
international sources.
However, the EPA's memorandum did not indicate that this type of
information alone was determinative of whether an alternative threshold
was in fact appropriate to justify use of a threshold in lieu of the
0.70 ppb level. Rather, the EPA determined that by capturing a
percentage of upwind state emissions comparable to the amount captured
at 1 percent, the alternative threshold may be appropriate, indicating
that a more determinative conclusion of appropriateness would require
further analysis. The MoDNR did not provide any further technical
justification to make that determination.
The EPA notes that in each case, the use of the alternative 1 ppb
threshold
[[Page 9542]]
would have the result of reducing the amount of cumulative upwind state
emissions that would be captured. While the EPA does not, in this
action, approve of the state's application of the 1 ppb threshold,
because the state has linkages greater than 1 ppb to projected downwind
nonattainment or maintenance receptors, the state's use of this
alternative threshold at Step 2 of the 4-step interstate framework
would not alter our review and proposed disapproval of this SIP
submittal.
The EPA here shares further evaluation of its experience since the
issuance of the August 2018 memorandum regarding use of alternative
thresholds at Step 2. This experience leads the Agency to now believe
it may not be appropriate to continue to attempt to recognize
alternative contribution thresholds at Step 2. The August 2018
memorandum stated that ``it may be reasonable and appropriate'' for
states to rely on an alternative threshold of 1 ppb at Step 2.\31\
However, the EPA also indicated that ``air agencies should consider
whether the recommendations in this guidance are appropriate for each
situation.'' Following receipt and review of 49 good neighbor SIP
submittals for the 2015 8-hour ozone NAAQS, the EPA's experience has
been that nearly every state that attempted to rely on a 1 ppb
threshold did not provide sufficient information and analysis to
support a determination that an alternative threshold was reasonable or
appropriate for that state.
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\31\ August 2018 memo at 4.
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For instance, in nearly all submittals, the states did not provide
the EPA with analysis specific to their state or the receptors to which
its emissions are potentially linked. In one case, the proposed
approval of Iowa's SIP submittal, the EPA expended its own resources to
attempt to supplement the information submitted by the state, in order
to more thoroughly evaluate the state-specific circumstances that could
support approval.\32\ It was at the EPA's sole discretion to perform
this analysis in support of the state's submittal, and the Agency is
not obligated to conduct supplemental analysis to fill the gaps
whenever it believes a state's analysis is insufficient. The Agency no
longer intends to undertake supplemental analysis of SIP submittals
with respect to alternative thresholds at Step 2 for purposes of the
2015 ozone NAAQS.
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\32\ Air Plan Approval; Iowa; Infrastructure State
Implementation Plan Requirements for the 2015 Ozone National Ambient
Air Quality Standard, 85 FR 12232 (March 2, 2020). The Agency
received adverse comment on this proposed approval and has not taken
final action with respect to this proposal.
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Furthermore, the EPA's experience since 2018 is that allowing for
alternative Step 2 thresholds may be impractical or otherwise
inadvisable for a number of additional policy reasons. For a regional
air pollutant such as ozone, consistency in requirements and
expectations across all states is essential. Based on its review of
submittals to-date and after further consideration of the policy
implications of attempting to recognize an alternative Step 2 threshold
for certain states, the Agency now believes the attempted use of
different thresholds at Step 2 with respect to the 2015 ozone NAAQS
raises substantial policy, consistency, and practical implementation
concerns.\33\ The availability of different thresholds at Step 2 has
the potential to result in inconsistent application of good neighbor
obligations based solely on the strength of a state's SIP submittal at
Step 2 of the 4-step interstate transport framework. From the
perspective of ensuring effective regional implementation of good
neighbor obligations, the more important analysis is the evaluation of
the emissions reductions needed, if any, to address a state's
significant contribution after consideration of a multifactor analysis
at Step 3, including a detailed evaluation that considers air quality
factors and cost. Where alternative thresholds for purposes of Step 2
may be ``similar'' in terms of capturing the relative amount of upwind
contribution (as described in the August 2018 memorandum), nonetheless,
use of an alternative threshold could allow certain states to avoid
further evaluation of potential emission controls while other states
must proceed to a Step 3 analysis. This can create significant equity
and consistency problems among states.
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\33\ We note that Congress has placed on the EPA a general
obligation to ensure the requirements of the CAA are implemented
consistently across states and regions. See CAA section 301(a)(2).
Where the management and regulation of interstate pollution levels
spanning many states is at stake, consistency in application of CAA
requirements is paramount.
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Further, it is not clear that national ozone transport policy is
best served by allowing for less stringent thresholds at Step 2. The
EPA recognized in the August 2018 memo that there was some similarity
in the amount of total upwind contribution captured (on a nationwide
basis) between 1percent and 1 ppb. However, the EPA notes that while
this may be true in some sense, that is hardly a compelling basis to
move to a 1 ppb threshold. Indeed, the 1 ppb threshold has the
disadvantage of losing a certain amount of total upwind contribution
for further evaluation at Step 3 (e.g., roughly seven percent of total
upwind state contribution was lost according to the modeling underlying
the August 2018 memorandum; \34\ in the EPA's updated modeling, the
amount lost is five percent). Considering the core statutory objective
of ensuring elimination of all significant contribution to
nonattainment or interference of the NAAQS in other states and the
broad, regional nature of the collective contribution problem with
respect to ozone, there does not appear to be a compelling policy
imperative in allowing some states to use a 1 ppb threshold while
others rely on a 1 percent of NAAQS threshold.
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\34\ See August 2018 memo, at 4.
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Consistency with past interstate transport actions such as CSAPR,
and the CSAPR Update and Revised CSAPR Update rulemakings (which used a
Step 2 threshold of 1 percent of the NAAQS for two less stringent ozone
NAAQS), is also important. Continuing to use a 1 percent of NAAQS
approach ensures that as the NAAQS are revised and made more stringent,
an appropriate increase in stringency at Step 2 occurs, so as to ensure
an appropriately larger amount of total upwind-state contribution is
captured for purposes of fully addressing interstate transport. Accord
76 FR 48237-38.
Therefore, notwithstanding the August 2018 memorandum's recognition
of the potential viability of alternative Step 2 thresholds, and in
particular, a potentially applicable 1 ppb threshold, the EPA's
experience since the issuance of that memo has revealed substantial
programmatic and policy difficulties in attempting to implement this
approach. Nonetheless, the EPA is not, at this time, rescinding the
August 2018 memorandum. The EPA invites comment on this broader
discussion of issues associated with alternative thresholds at Step 2.
Depending on comment and further evaluation of this issue, the EPA may
determine to rescind the August 2018 memorandum in the future.
MoDNR used two arguments at Step 2 for excluding the nonattainment
receptor in Sheboygan, Wisconsin, (Monitor ID: 551170006). First, the
State utilized a 2 ppb threshold at Step 2 to identify whether the
state was ``linked'' to this receptor. Second, the state argued that
any reductions from Missouri would have a de minimis or minimal effect
on air quality improvements at this receptor due to the larger impacts
from other states such as Wisconsin,
[[Page 9543]]
Illinois and Indiana. The EPA discusses both of these arguments in this
section.
In its analysis, the state argued that because a 2 ppb threshold
would capture 68.2% of cumulative upwind state contributions at the
Sheboygan receptor, similar to the ``approximately 70 percent of total
upwind contribution'' captured on average nationwide at the 1 ppb
threshold the EPA identified in the August 2018 memorandum, a 2 ppb
threshold is appropriate to use at this receptor. While the EPA had
determined that an alternative threshold that would capture a
sufficient percentage of upwind state emissions comparable to the
amount that would be captured at the level of 1 percent of the NAAQS
may be appropriate, the Agency also indicated that more analysis would
be needed to reach a determinative conclusion of appropriateness. As
explained with respect to the alternative 1 ppb threshold that MoDNR
sought to use for the for the receptors in Wayne Michigan, Milwaukee,
Wisconsin and both Texas receptors, it did not provide any further
technical justification to make the determination.
As explained with respect to the potential use of an alternative 1
ppb threshold, the EPA's experience since the issuance of the 2018
memorandum discussing the issue has revealed substantial programmatic
and policy difficulties in attempting to implement this approach even
for a 1 ppb threshold. At no point did the EPA suggest that a 2 ppb
threshold might be appropriate for this purpose under any
circumstances. Such a threshold would be higher than the threshold that
the EPA has historically used in interstate transport rules that courts
have approved (i.e., 1 percent of the NAAQS at issue), or that the EPA
has considered even potentially appropriate if it were to achieve
functionally the same air quality impacts (i.e., 1 ppb).
The second argument that the state used to exclude the Sheboygan,
Wisconsin receptor in Step 2 was related to emissions from other
states. The state argued that the primary contributors to the projected
ozone concentrations in Sheboygan are the upwind states of Illinois and
Indiana and the home state itself, Wisconsin. The EPA's 2018 modeling
showed these states would contribute a combined 31.93 ppb in 2023 to
the Sheboygan receptor. However, the state's reasoning related to
Indiana, Illinois and Wisconsin emissions is inapplicable to the
requirements of CAA section 110(a)(2)(D)(i)(I). The good neighbor
provision requires states and the EPA to address interstate transport
of air pollution that contributes to downwind states' ability to attain
and maintain NAAQS. Whether emissions from other states also contribute
to the same downwind air quality issue is irrelevant in assessing
whether a downwind state has an air quality problem, or whether the
upwind state at issue state is significantly contributing to that
problem. The Ozone NAAQS nonattainment and maintenance problems that
result from interstate transport are typically the result of cumulative
impacts from multiple states. States are not obligated under CAA
section 110(a)(2)(D)(i)(I) to reduce emissions only if doing so would
be sufficient in isolation to resolve all downwind nonattainment or
maintenance problems. Rather, each state is obligated to eliminate its
own ``significant contribution'' or ``interference'' with the ability
of other states to attain or maintain the NAAQS.
Indeed, the D.C. Circuit in Wisconsin specifically rejected
petitioner arguments suggesting that upwind states should be excused
from good neighbor obligations on the basis that some other source of
emissions (whether international or another upwind state) could be
considered the ``but-for'' cause of downwind air quality problem. 938
F.3d 303 at 323-324. The court viewed petitioners' arguments as
essentially an argument ``that an upwind State `contributes
significantly' to downwind nonattainment only when its emissions are
the sole cause of downwind nonattainment.'' 938 F.3d 303 at 324. The
court explained that ``an upwind State can `contribute' to downwind
nonattainment even if its emissions are not the but-for cause.'' Id. at
324-325. See also Catawba County v. EPA, 571 F.3d 20, 39 (D.C. Cir.
2009) (rejecting the argument ``that `significantly contribute'
unambiguously means `strictly cause' '' because there is ``no reason
why the statute precludes EPA from determining that [an] addition of
[pollutant] into the atmosphere is significant even though a nearby
county's nonattainment problem would still persist in its absence'');
Miss. Comm'n on Envtl. Quality v. EPA, 790 F.3d 138, 163 n.12 (D.C.
Cir. 2015) (observing that the argument that ``there likely would have
been no violation at all . . . if it were not for the emissions
resulting from [another source]'' is ``merely a rephrasing of the but-
for causation rule that we rejected in Catawba County.''). Therefore, a
state is not excused from eliminating its significant contribution on
the basis that other states' emissions also contribute some amount of
pollution to the same receptors to which the state is linked. As a
result, Step 3 analysis of the 4-Step Interstate Transport Framework is
necessary.
Thus, the EPA proposes that MoDNR's submittal did not adequately
justify the use of an alternative threshold or otherwise establish that
it should not be considered linked at Step 2. The EPA proposes to apply
the 1 percent of NAAQS threshold, consistent with the discussion in
this subsection. Under the proposed 1 percent threshold, both in the
modeling available to the state at the time it made its submittal, and
under the newly available 2023 modeling discussed below, Missouri is
linked to downwind nonattainment and maintenance receptors.\35\
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\35\ Because the EPA finds that the MoDNR submittal's arguments
with respect to its linkages in the modeling it relied on are not
sufficient or technically justified to conclude the state is not
linked to downwind receptors, the EPA can also conclude that the
same arguments would not be meritorious even if applied with respect
to the receptor linkages the EPA finds in its more recent 2023
modeling using the 2016v2 emissions platform.
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3. Results of the EPA's Step 1 and Step 2 Modeling and Findings for
Missouri
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 EPA examined these data to determine if
emissions in Missouri 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 in this most recent round of modeling. As shown
in Table 2, the data indicate that in 2023, emissions from sources in
Missouri contribute greater than 1 percent of the NAAQS to
nonattainment or maintenance-only receptors in Racine County and
Kenosha County, Wisconsin, and Cook County, Illinois.\36\ Therefore,
based on the EPA's evaluation of the information submitted by MoDNR,
and based on the EPA's most recent modeling results for 2023, the EPA
proposes to find that Missouri 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.
---------------------------------------------------------------------------
\36\ 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.
[[Page 9544]]
Table 2--Missouri Linkage Results Based on the EPA Updated 2023 Modeling
--------------------------------------------------------------------------------------------------------------------------------------------------------
2023 Average 2023 Maximum
Receptor ID Location Nonattainment/maintenance design value design value MO contribution
(ppb) (ppb) (ppb)
--------------------------------------------------------------------------------------------------------------------------------------------------------
550590025................................ Kenosha, Wisconsin.......... Maintenance................. 69.2 72.3 1.66
550590019................................ Kenosha, Wisconsin.......... Nonattainment............... 72.8 73.7 1.08
170317002................................ Cook, Illinois.............. Maintenance................. 70.1 73.0 0.94
551010020................................ Racine, Wisconsin........... Nonattainment............... 71.3 73.2 0.92
--------------------------------------------------------------------------------------------------------------------------------------------------------
4. 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).
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.
MoDNR did not conduct such an analysis in its SIP submission, as a
result of its conclusions pursuant to Step 1 and Step 2 of its analysis
with respect to the six receptors that the EPA previously identified.
As explained in connection with the evaluation of MoDNR's Step 1 and
Step 2 analyses, the EPA disagrees with those analyses and accordingly
the State should have evaluated effectively which emissions in the
State should be deemed ``significant'' and therefore prohibited, in its
SIP submission. We therefore propose that MoDNR was required to analyze
emissions from the sources and other emissions activity from within the
state to determine whether its contributions were significant, and we
propose to disapprove its submission because MoDNR failed to do so.
5. 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. As mentioned previously,
Missouri's SIP submission did not contain an evaluation of additional
emission control opportunities (or establish that no additional
controls are required), thus, no information was provided at step 4. As
a result, the EPA proposes to disapprove Missouri' submittal on the
separate, additional basis that the State has not developed permanent
and enforceable emissions reductions necessary to meet the obligations
of CAA section 110(a)(2)(d)(i)(I).
6. Conclusion
Based on the EPA's evaluation of the MoDNR's SIP submission, the
EPA is proposing to find that the MoDNR's June 10, 2019 SIP submission
addressing CAA section 110(a)(2)(D)(i)(I) does not meet the State's
interstate transport obligations, because it fails to contain the
necessary provisions to eliminate emissions that will contribute
significantly to nonattainment or interfere with maintenance of the
2015 8-hour ozone NAAQS in any other state.
IV. Proposed Action
We are proposing to disapprove the MoDNR's June 10, 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 Missouri 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 SIP that meets these requirements. Disapproval does not
start a mandatory sanctions clock for Missouri.
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 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
[[Page 9545]]
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 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).\37\
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\37\ In deciding whether to invoke the exception by making and
publishing a finding that an action is based on a determination of
nationwide scope or effect, the Administrator takes into account a
number of policy considerations, including his judgment balancing
the benefit of obtaining the D.C. Circuit's authoritative
centralized review versus allowing development of the issue in other
contexts and the best use of Agency resources.
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If 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 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 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 approach to nonattainment
and maintenance receptors and a nationally uniform approach to
contribution threshold analysis.\38\ 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).\39\
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\38\ 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.
\39\ The EPA may take a consolidated, single final action on all
of the proposed SIP disapproval actions with respect to obligations
under CAA section 110(a)(2)(D)(i)(I) for the 2015 ozone NAAQS.
Should EPA take a single final action on all such disapprovals, this
action would be nationally applicable, and the EPA would also
anticipate, in the alternative, making and publishing a finding that
such final action is based on a determination of nationwide scope or
effect.
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List of Subjects in 40 CFR Part 52
Environmental protection, Air pollution control, Incorporation by
reference, Ozone.
Authority: 42 U.S.C. 7401 et seq.
Dated: February 9, 2022.
Meghan A. McCollister,
Regional Administrator, Region 7.
[FR Doc. 2022-03183 Filed 2-18-22; 8:45 am]
BILLING CODE 6560-50-P
