Air Plan Disapproval; Arkansas, Louisiana, Oklahoma, and Texas; Interstate Transport of Air Pollution for the 2015 8-Hour Ozone National Ambient Air Quality Standards, 9798-9835 [2022-02961]
Download as PDF
<![CDATA[
9798
Federal Register / Vol. 87, No. 35 / Tuesday, February 22, 2022 / Proposed Rules
ENVIRONMENTAL PROTECTION
AGENCY
40 CFR Part 52
[EPA–R06–OAR–2021–0801, EPA–HQ–
OAR–2021–0663; FRL–9338–01–R6]
Air Plan Disapproval; Arkansas,
Louisiana, Oklahoma, and Texas;
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
or Agency) is proposing to disapprove
State Implementation Plan (SIP)
submittals from Arkansas, Louisiana,
Oklahoma and Texas regarding
interstate transport for the 2015 8-hour
ozone national ambient air quality
standard (NAAQS). This 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. The ‘‘good neighbor’’ or
‘‘interstate transport’’ 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–R06–
OAR–2021–0801, by any of the
following methods: Federal
eRulemaking Portal at https://
www.regulations.gov following the
online instructions for submitting
comments or via email to fuerst.sherry@
epa.gov. Include Docket ID No. EPA–
R06–OAR–2021–0801 in the subject line
of the message.
Instructions: All comments submitted
must include the Docket ID No. for this
rulemaking. Comments received may be
posted without change to https://
www.regulations.gov/, including any
lotter on DSK11XQN23PROD with PROPOSALS2
SUMMARY:
VerDate Sep<11>2014
20:06 Feb 18, 2022
Jkt 256001
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 the EPA Docket Center
services and the current status, please
visit us online at https://www.epa.gov/
dockets.
FOR FURTHER INFORMATION CONTACT:
Sherry Fuerst, EPA Region 6 Office, AR–
SI, 214–665–6454, fuerst.sherry@
epa.gov. We encourage the public to
submit comments via https://
www.regulations.gov, as there will be a
delay in processing mail and no courier
or hand deliveries will be accepted.
Please call or email the contact above if
you need alternative access to material
indexed but not provided in the docket.
SUPPLEMENTARY INFORMATION: Public
Participation: Submit your comments,
identified by Docket ID No. EPA–R06–
OAR–2021–0801, 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
the 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–R06–OAR–2021–0801 and
EPA–HQ–OAR–2021–0663. Docket No.
EPA–R06–OAR–2021–0801 contains
information specific to Arkansas,
Louisiana, Oklahoma, and Texas,
including the notice of proposed
rulemaking, submittals from the states,
and the EPA Region 6 2015 8-Hour
Ozone Transport SIP Proposal Technical
Support Document (EPA Region 6 TSD).
PO 00000
Frm 00002
Fmt 4701
Sfmt 4702
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,
including Preparation of Emissions
Inventories for the 2016v2 North
American Emissions Modeling Platform,
and Air Quality Modeling TSD for 2015
ozone NAAQS Transport SIP Proposed
Actions. All comments regarding
information in either of these dockets
are to be made in Docket No. EPA–R06–
OAR–2021–0801. For additional
submission methods, please contact
Sherry Fuerst, 214–665–6454,
fuerst.sherry@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-epadockets. 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 dockets for this
action, Docket No. EPA–R06–OAR–
2021–0801 and EPA–HQ–OAR–2021–
0663, are available electronically at
https://www.regulations.gov. While all
documents in the docket are listed in
the index, some information may not be
publicly available due to docket file size
restrictions or content (e.g., CBI).
Throughout this document, ‘‘we,’’
‘‘us,’’ and ‘‘our’’ means the EPA.
Table of Contents
I. Background
A. Description of Statutory Background
B. Description of the EPA’s 4-Step
Interstate Transport Regulatory Process
C. Background on the EPA’s Ozone
Transport Modeling Information
D. The EPA’s Approach to Evaluating
Interstate Transport SIPs for the 2015
Ozone NAAQS
1. Selection of Analytic Year
2. Step 1 of the 4-Step Interstate Transport
Framework
3. Step 2 of the 4-Step Interstate Transport
Framework
E:\FR\FM\22FEP2.SGM
22FEP2
lotter on DSK11XQN23PROD with PROPOSALS2
Federal Register / Vol. 87, No. 35 / Tuesday, February 22, 2022 / Proposed Rules
4. Step 3 of the 4-Step Interstate Transport
Framework
5. Step 4 of the 4-Step Interstate Transport
Framework
II. Arkansas SIP Submission Addressing
Interstate Transport of Air Pollution for
the 2015 Ozone NAAQS and the EPA
Evaluation of the SIP Submission
A. Summary of ADEQ SIP Submission
Addressing Interstate Transport of Air
Pollution for the 2015 Ozone NAAQS
B. EPA Evaluation of the ADEQ SIP
Submission
1. Evaluation of Information Provided by
ADEQ Regarding Step 1
2. Evaluation of Information Provided by
ADEQ Regarding Step 2
3. Results of the EPA’s Step 1 and Step 2
Modeling and Findings for Arkansas
4. Evaluation of Information Provided by
ADEQ Regarding Step 3
5. Evaluation of Information Provided by
ADEQ Regarding Step 4
6. Conclusion
III. Louisiana SIP Submission Addressing
Interstate Transport of Air Pollution for
the 2015 Ozone NAAQS and the EPA
Evaluation of the SIP Submission
A. Summary of LDEQ SIP Submission
Addressing Interstate Transport of Air
Pollution for the 2015 Ozone NAAQS
B. EPA Evaluation of the LDEQ SIP
Submission
1. Evaluation of Information Provided by
LDEQ Regarding Steps 1 and 2
2. Results of the EPA’s Step 1 and Step 2
Modeling and Findings for Louisiana
3. Evaluation of Information Provided by
LDEQ Regarding Step 3
4. Evaluation of Information Provided by
LDEQ Regarding Step 4
5. Conclusion
IV. Oklahoma SIP Submission Addressing
Interstate Transport of Air Pollution for
the 2015 Ozone NAAQS and the EPA
Evaluation of the SIP Submission
A. Summary of ODEQ SIP Submission
Addressing Interstate Transport of Air
Pollution for the 2015 Ozone NAAQS
B. EPA Evaluation of the ODEQ SIP
Submission
1. Evaluation of Information Provided by
ODEQ Regarding Steps 1 and 2
2. Results of the EPA’s Step 1 and Step 2
Modeling and Findings for Oklahoma
3. Evaluation of Information Provided by
ODEQ Regarding Step 3
4. Evaluation of Information Provided by
ODEQ Regarding Step 4
5. Conclusion
C. Impact on Areas of Indian Country
V. Texas SIP Submission Addressing
Interstate Transport of Air Pollution for
the 2015 Ozone NAAQS and the EPA
Evaluation of the SIP Submission
A. Summary of TCEQ SIP Submission
Addressing Interstate Transport of Air
Pollution for the 2015 Ozone NAAQS
B. EPA Evaluation of the TCEQ SIP
Submission
1. Evaluation of Information Provided by
TCEQ Regarding Step 1
i. Evaluation of TCEQ’s Methodology for
Identifying Maintenance Receptors
ii. Evaluation of the TCEQ Modeling
2. Evaluation of Information Provided by
TCEQ Regarding Step 2
VerDate Sep<11>2014
20:06 Feb 18, 2022
Jkt 256001
3. Results of the EPA’s Step 1 and Step 2
Modeling and Findings for Texas
4. Evaluation of Information Provided by
TCEQ Regarding Step 3
5. Evaluation of Information Provided by
TCEQ Regarding Step 4
6. Conclusion
VI. Proposed Action
VII. Statutory and Executive Order Reviews
I. Background
A. Description of Statutory Background
On October 1, 2015, the EPA
promulgated a revision to the 2015 8hour ozone NAAQS (2015 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 requirements, often referred to
as ‘‘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 4-Step
Interstate Transport Regulatory Process
The EPA is using the 4-Step interstate
transport framework (or 4-Step
framework) described in detail below to
evaluate states’ SIP submittals
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).
PO 00000
Frm 00003
Fmt 4701
Sfmt 4702
9799
addressing the interstate transport
provision for the 2015 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 CrossState 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
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 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.
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 See ‘‘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).
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).
E:\FR\FM\22FEP2.SGM
22FEP2
9800
Federal Register / Vol. 87, No. 35 / Tuesday, February 22, 2022 / Proposed Rules
C. Background on the EPA’s Ozone
Transport Modeling Information
lotter on DSK11XQN23PROD with PROPOSALS2
In general, the EPA has performed
nationwide air quality modeling to
project ozone design values (DVs) 8
which are used in combination with
measured data to identify
nonattainment and maintenance
receptors. To quantify the contribution
of emissions from specific upwind
states on 2023 ozone DVs for the
identified downwind nonattainment
and maintenance receptors, the EPA
performed nationwide, state-level ozone
source apportionment modeling for
2023. The source apportionment
modeling provided contributions to
ozone at receptors from precursor
emissions of anthropogenic nitrogen
oxides (NOX) and volatile organic
compounds (VOCs) in individual
upwind states.
The EPA has released several
documents containing projected ozone
design values, contributions, and
information relevant to evaluating
interstate transport with respect to the
2015 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 DVs and interstate
contributions for 2023 using a 2011 base
year platform.9 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
NAAQS.10 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.11 On March 27,
8 A design value is a statistic that describes the
air quality status of a given location relative to the
level of the NAAQS. Design values are typically
used to designate and classify nonattainment areas,
as well as to assess progress towards meeting the
NAAQS. See https://www.epa.gov/air-trends/airquality-design-values#report.
9 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).
10 82 FR at 1735.
11 See EPA memorandum, ‘‘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, (‘‘October 2017
memorandum’’) available in Docket ID No. EPA–
HQ–OAR–2021–0663 or at https://www.epa.gov/
VerDate Sep<11>2014
20:06 Feb 18, 2022
Jkt 256001
2018, we issued a memorandum (March
2018 memorandum) noting that the
same 2023 modeling data released in the
October 2017 memorandum could also
be useful for identifying potential
downwind air quality problems with
respect to the 2015 ozone NAAQS at
Step 1 of the 4-Step framework.12 The
March 2018 memorandum also included
the then newly available contribution
modeling data to assist states in
evaluating their impact on potential
downwind air quality problems for the
2015 ozone NAAQS under Step 2 of the
4-Step framework.13 The EPA
subsequently issued two more
memoranda in August and October
2018, providing additional information
to states developing interstate transport
SIP submissions for the 2015 ozone
NAAQS concerning, respectively,
potential contribution thresholds that
may be appropriate to apply in Step 2
of the 4-Step interstate transport
framework, and considerations for
identifying downwind areas that may
have problems maintaining the standard
at Step 1 of the 4-Step interstate
transport framework.14
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
interstate-air-pollution-transport/interstate-airpollution-transport-memos-and-notices.
12 See EPA memorandum, ‘‘Information on the
Interstate Transport State Implementation Plan
Submissions for the 2015 Ozone National Ambient
Air Quality Standards under Clean Air Act section
110(a)(2)(D)(i)(I)’’, March 27, 2018, (‘‘March 2018
memorandum’’) available in Docket ID No. EPA–
HQ–OAR–2021–0663 or at https://www.epa.gov/
interstate-air-pollution-transport/interstate-airpollution-transport-memos-and-notices.
13 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 interstate transport provision. Any such
determination would be made through notice-andcomment rulemaking.’’
14 See EPA memorandums, ‘‘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 (‘‘October 2018 memorandum’’),
available in Docket ID No. EPA–HQ–OAR–2021–
0663 or at https://www.epa.gov/airmarkets/memoand-supplemental-information-regarding-interstatetransport-sips-2015-ozone-naaqs.
PO 00000
Frm 00004
Fmt 4701
Sfmt 4702
collaborative project.15 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 DVs 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.16
See 85 FR 68964, 68981. Although the
Revised CSAPR Update addressed
transport for the 2008 ozone NAAQS,
the projected DVs and contributions
from the 2016v1 platform are also useful
for identifying downwind ozone
problems and linkages with respect to
the 2015 ozone NAAQS.17
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 18 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 Technical Support
Document (TSD) Preparation of
Emissions Inventories for the 2016v2
North American Emissions Modeling
Platform, which is included in Docket
ID No. EPA–HQ–OAR–2021–0663. The
EPA performed air quality modeling of
the 2016v2 emissions using the most
recent publicly released version of the
Comprehensive Air-quality Model with
extensions (CAMx) photochemical
modeling, version 7.10.19 The EPA now
proposes to rely on the air quality
modeling performed using CAMx,
version 7.10, and the newly available
2016v2 emissions platform in evaluating
states’ submissions with respect to Steps
15 The results of this modeling, as well as the
underlying modeling files, are included in Docket
ID No. EPA–HQ–OAR–2021–0663.
16 See 85 FR 68964, 68981 (Oct. 30, 2020).
17 See the Air Quality Modeling Technical
Support Document for the Final Revised Cross-State
Air Pollution Rule Update, available in Docket ID
No. EPA–HQ–OAR–2021–0063 for this action.
18 Additional details and documentation related
to the MOVES3 model can be found at https://
www.epa.gov/moves/latest-version-motor-vehicleemission-simulator-moves.
19 Ramboll Environment and Health, January
2021, www.camx.com.
E:\FR\FM\22FEP2.SGM
22FEP2
Federal Register / Vol. 87, No. 35 / Tuesday, February 22, 2022 / Proposed Rules
1 and 2 of the 4-Step framework and
generally referenced within this action
as 2016v2 modeling for 2023. By using
the updated modeling results, the EPA
is using the most current and
technically appropriate information for
this proposed rulemaking. Sections II–V
of this action and the Air Quality
Modeling TSD for 2015 ozone NAAQS
Transport SIP Proposed Actions,
included in Docket ID No. EPA–HQ–
OAR–2021–0663 for this proposal,
contain additional detail on the EPA’s
2016v2 modeling. In this action, the
EPA is inviting public comment on this
updated 2023 modeling, which uses a
2016v2 emissions platform. Per the
instructions in the Supplementary
Information section above, all public
comments, including comments on the
EPA’s air quality modeling should be
submitted in the Regional docket for
this action, Docket ID No. EPA–R06–
OAR–2021–0801. Comments are not
being accepted in Docket No. EPA–HQ–
OAR–2021–0663.
States may have chosen to rely on the
results of 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 Sections II–V of this
action, we evaluate how the states used
air quality modeling information in
their submissions.
lotter on DSK11XQN23PROD with PROPOSALS2
D. The EPA’s Approach to Evaluating
Interstate Transport SIPs for the 2015
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 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 regionalscale pollution problem involving many
smaller contributors. Effective policy
solutions to the problem of interstate
ozone transport going back to the 1998
NOX SIP Call 20 have necessitated the
application of a uniform framework of
policy judgments in order to ensure an
‘‘efficient and equitable’’ approach. See
20 See
63 FR 57356. The NOX SIP Call required
22 eastern states and the District of Columbia to
submit state implementation plans (SIPs) that set
statewide ozone season NOx budgets which would
reduce emissions of NOX.
VerDate Sep<11>2014
20:06 Feb 18, 2022
Jkt 256001
EME Homer City Generation, LP v. EPA,
572 U.S. 489, 519 (2014).
In the March, August, and October
2018 memoranda, the EPA recognized
that states may be able to establish
alternative approaches to addressing
their interstate transport obligations for
the 2015 ozone NAAQS that vary from
a nationally uniform framework. The
EPA emphasized in these memoranda,
however, that such alternative
approaches must be technically justified
and appropriate in light of the facts and
circumstances of each particular state’s
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.21 However,
the EPA made clear in Attachment A
that the list of ideas were not
suggestions endorsed by the Agency but
rather ‘‘comments provided in various
forums’’ on which the EPA sought
‘‘feedback from interested
stakeholders.’’ 22 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.’’ 23 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 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,
21 March
22 Id.
2018 memorandum, Attachment A.
at A–1.
23 Id.
PO 00000
Frm 00005
Fmt 4701
Sfmt 4702
9801
definition of nonattainment and
maintenance receptors, selection of
contribution threshold, and multifactor
control strategy analysis.
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).24 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
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 interstate transport
provision, to assess downwind air
quality as expeditiously as practicable
and no later than the next applicable
24 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).
E:\FR\FM\22FEP2.SGM
22FEP2
9802
Federal Register / Vol. 87, No. 35 / Tuesday, February 22, 2022 / Proposed Rules
attainment date,25 which is now the
Moderate area attainment date under
CAA section 181 for ozone
nonattainment. The Moderate area
attainment date for the 2015 ozone
NAAQS is August 3, 2024.26 The EPA
believes that 2023 is now the
appropriate year for analysis of
interstate transport obligations for the
2015 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 ozone NAAQS.
The EPA recognizes that the
attainment date for nonattainment areas
classified as Marginal for the 2015
ozone NAAQS was August 3, 2021.
Under the Maryland holding, any
necessary emissions reductions to
satisfy interstate transport obligations
should have been implemented by no
later than this date. At the time of the
statutory deadline to submit interstate
transport SIPs (October 1, 2018), many
states relied upon the EPA modeling of
the year 2023, and no state provided an
alternative analysis using a 2021
analytic year (or the prior 2020 ozone
season). However, the EPA must act on
SIP submittals using the information
available at the time it takes such action.
In this circumstance, the EPA does not
believe it would be appropriate to
evaluate states’ obligations under CAA
section 110(a)(2)(D)(i)(I) as of an
attainment date that is wholly in the
past, because the Agency interprets the
interstate transport provision as forward
looking. See 86 FR at 23074; see also
Wisconsin, 938 F.3d at 322.
Consequently, in this proposal the EPA
proposes to 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 ozone NAAQS.
lotter on DSK11XQN23PROD with PROPOSALS2
2. Step 1 of the 4-Step Interstate
Transport Framework
In Step 1, the EPA identifies
monitoring sites that are projected to
25 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 4-Step 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.
26 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).
VerDate Sep<11>2014
20:06 Feb 18, 2022
Jkt 256001
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 framework. For sites
that are identified as a nonattainment or
maintenance receptor in 2023, we
proceed to the next step of our 4-Step
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.27
For the purpose of this proposal, the
EPA identifies ‘‘nonattainment’’
receptors as those monitoring sites that
are projected to have average DVs in
2023 that exceed the NAAQS and that
are also measuring nonattainment based
on the most recent monitored DVs. 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).28
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).29 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
27 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)).
28 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).
29 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).
PO 00000
Frm 00006
Fmt 4701
Sfmt 4702
quality was determined by evaluating
the ‘‘maximum’’ future DV at each
receptor based on a projection of the
maximum measured DV over the
relevant period. The EPA interprets the
projected maximum future DV 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 DV 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 DV 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 DVs above the level of
the applicable NAAQS, but that are not
currently measuring nonattainment
based on the most recent official DVs. In
addition, those monitoring sites with
projected average DVs below the
NAAQS, but with projected maximum
DVs above the NAAQS are also
identified as ‘‘maintenance only’’
receptors, even if they are currently
measuring nonattainment based on the
most recent official DVs.
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 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
E:\FR\FM\22FEP2.SGM
22FEP2
lotter on DSK11XQN23PROD with PROPOSALS2
Federal Register / Vol. 87, No. 35 / Tuesday, February 22, 2022 / Proposed Rules
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 of
controls as part of a multifactor 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 continue 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 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. For ozone, as the
EPA found in the Clean Air Interstate
Rule (CAIR), CSAPR, and CSAPR
Update, a portion of the nonattainment
problem 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 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
VerDate Sep<11>2014
20:06 Feb 18, 2022
Jkt 256001
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
analysis 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 costeffectiveness 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 welldocumented evaluation determining
whether their emissions constitute
significant contribution or interference
with maintenance by preparing a
multifactor assessment that evaluates
additional available control
opportunities. 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.30
30 As examples of general approaches for how
such an analysis could be conducted for their
PO 00000
Frm 00007
Fmt 4701
Sfmt 4702
9803
5. Step 4 of the 4-Step Interstate
Transport Framework
In Step 4, states (or the EPA) develop
permanent and federally enforceable
control strategies to achieve the
emissions reductions determined to be
necessary in Step 3 to eliminate
significant contribution to
nonattainment or interference with
maintenance of the NAAQS. For a state
linked in Steps 1 and 2 to rely on an
emissions control measure in 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
section 110(a)(2)(A); Committee for a
Better Arvin v. U.S. E.P.A., 786 F.3d
1169, 1175–76 (9th Cir. 2015) (holding
that measures relied on by state to meet
CAA requirements must be included in
the SIP).
II. Arkansas SIP Submission
Addressing Interstate Transport of Air
Pollution for the 2015 Ozone NAAQS
and the EPA Evaluation of the SIP
Submission
A. Summary of ADEQ SIP Submission
Addressing Interstate Transport of Air
Pollution for the 2015 Ozone NAAQS
On October 10, 2019, the Arkansas
Division of Environmental Quality
(ADEQ) of the Arkansas Department of
Energy and Environment made a SIP
submission addressing interstate
transport of air pollution for the 2015
ozone NAAQS. The ADEQ SIP
submission provided an analysis of
Arkansas’s air emissions impact to
downwind states using the EPA’s 4-Step
framework and an analytic year of 2023
and concluded that the State’s air
emissions will not contribute
significantly to nonattainment or
interfere with maintenance of the 2015
ozone NAAQS in other states.
To identify downwind monitors
projected to be in nonattainment and/or
have maintenance issues in 2023 (Step
1), ADEQ relied on the EPA’s interstate
transport modeling results that are
included as an attachment to the March
2018 memorandum. The EPA modeling
results included with the March 2018
memorandum provide: (1) Projected
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.
E:\FR\FM\22FEP2.SGM
22FEP2
9804
Federal Register / Vol. 87, No. 35 / Tuesday, February 22, 2022 / Proposed Rules
average DV and maximum DV for the
future year 2023 (fy 2023) for ozone
monitors projected to be potential
nonattainment or maintenance receptors
in the 48 contiguous States and (2) the
expected contribution of State emissions
to the projected ozone concentrations at
each ozone monitor.
At Step 2, ADEQ identified those
states to which Arkansas contributes
emissions and then applied a 1 ppb
contribution threshold to determine
projected nonattainment and/or
maintenance receptors in other states
that might be significantly impacted by
emissions from Arkansas. ADEQ
provided three rationales as a basis to
support their decision to rely on a 1 ppb
contribution threshold. First, ADEQ
cited to the August 2018
memorandum 31 that compares the
collective contribution captured by
three different contribution thresholds:
1 Percent of the NAAQS, 1 ppb, and 2
ppb. ADEQ summarized the August
2018 memorandum and concluded that
the 1 percent and 1 ppb contribution
thresholds are generally comparable.
Second, ADEQ referenced an April 2018
memorandum 32 in which the EPA
examined the use of a significant impact
level (SIL) value of 1 ppb for
determining whether a proposed
prevention of significant deterioration
(PSD) source causes or contributes to a
violation of the corresponding 2015
ozone NAAQS. Despite recognizing that
a contribution threshold is not the same
as a significance level, ADEQ claimed
that a contribution threshold and
significance level are sufficiently
analogous to support the use of a 1 ppb
contribution threshold. The final
rationale ADEQ provided was based on
the consistency with the reported
precision of Federal reference monitors
for ozone and the rounding
requirements found in 40 CFR part 50,
Appendix U, Interpretation of the
Primary and Secondary National
Ambient Air Quality Standards for
Ozone. ADEQ noted that the 1 percent
contribution threshold of 0.7 ppb is
lower than the manufacturer’s reported
precision of Federal reference monitors
for ozone and that the requirements
found in Appendix U truncates monitor
values of 0.7 ppb to 0 ppb.
As stated previously, ADEQ identified
all potential nonattainment and
maintenance receptors for fy 2023
showing a contribution of emissions
from Arkansas.33 These receptors are
included in Table AR–1.
TABLE AR–1—PROJECTED NONATTAINMENT AND MAINTENANCE RECEPTORS IDENTIFIED BY ARKANSAS BASED ON THE
EPA’S MARCH 2018 MEMORANDUM
2023
average DV
(ppb)
Receptor
(site ID, county, state)
lotter on DSK11XQN23PROD with PROPOSALS2
260050003, Allegan, MI ...............................................................................................................
482011039, Harris, TX ................................................................................................................
480391004, Brazoria, TX .............................................................................................................
484392003, Tarrant, TX ..............................................................................................................
481210034, Denton, TX ..............................................................................................................
482011034, Harris, TX ................................................................................................................
551170006, Sheboygan, WI ........................................................................................................
550790085, Milwaukee, WI .........................................................................................................
482010024, Harris, TX ................................................................................................................
261630019, Wayne, MI ...............................................................................................................
240251001, Harford, MD .............................................................................................................
90019003, Fairfield, CT ...............................................................................................................
90013007, Fairfield, CT ...............................................................................................................
361030002, Suffolk, NY ...............................................................................................................
360810124, Queens, NY .............................................................................................................
90099002, New Haven, CT .........................................................................................................
90010017, Fairfield, CT ...............................................................................................................
80590006, Jefferson, CO ............................................................................................................
80590011, Jefferson, CO ............................................................................................................
81230009, Weld, CO ...................................................................................................................
80350004, Douglas, CO ..............................................................................................................
69
71.8
74
72.5
69.7
70.8
72.8
71.2
70.4
69
70.9
73
71
74
70.2
69.9
68.9
71.3
70.9
70.2
71.1
2023
maximum DV
(ppb)
71.7
73.5
74.9
74.8
72
71.6
75.1
73
72.8
71
73.3
75.9
75
75.5
72
72.6
71.2
73.7
73.9
71.4
73.2
Arkansas
contribution
(ppb)
1.64
0.99
0.90
0.78
0.58
0.54
0.51
0.40
0.29
0.27
0.17
0.13
0.13
0.12
0.09
0.08
0.07
0.03
0.02
0.02
0.01
Based on a 1 ppb contribution
threshold, ADEQ identified only one fy
2023 projected maintenance receptor,
Allegan County, MI, and no fy 2023
projected nonattainment receptors
linked to Arkansas. ADEQ also cited
other modeling performed by TCEQ and
Midwest Ozone Group, which showed
that when different modeling protocols
were employed, future year DV
projections and contributions could
differ considerably. ADEQ therefore
elected to consider other evidence
regarding its linkage to air quality in
Allegan County, MI. Specifically, ADEQ
analyzed back trajectory information to
infer that there is no consistent or
persistent relationship between elevated
ozone days in Allegan County, MI and
air traveling through Arkansas. ADEQ
assessed wind patterns on elevated
ozone days—days with a maximum
daily average 8-hour ozone (MDA8)
greater than 70.9 ppb in Allegan County,
31 ‘‘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, available in Docket ID
No. EPA–HQ–OAR–2021–0663 or at https://
www.epa.gov/airmarkets/memo-and-supplementalinformation-regarding-interstate-transport-sips2015-ozone-naaqs.
32 See EPA memorandum from Peter Tsirigotis,
Director of the Office of Air Quality planning and
Standards, April 17, 2018, ‘‘Guidance on Significant
Impact Levels for Ozone and Fine Particles in the
Prevention of Significant Deterioration Permitting
Program’’ (‘‘SILs Guidance’’ or ‘‘April 2018
memorandum’’), available at: https://www.epa.gov/
sites/default/files/2018-04/documents/sils_policy_
guidance_document_final_signed_4-17-18.pdf.
33 Table AR–1 lists all sites that the EPA projected
to have a fy 2023 average DV or fy 2023 maximum
DV greater than 70.9 ppb in our March 2018
memorandum. As Arkansas stated in the SIP
submission, the EPA considers sites matching these
criteria to be projected nonattainment areas and
projected maintenance areas, respectively. ADEQ
ranked these sites by Arkansas’s potential
contribution, which the EPA determined based on
the daily eight-hour average contributions on the
top ten concentration days in 2023.
VerDate Sep<11>2014
20:06 Feb 18, 2022
Jkt 256001
PO 00000
Frm 00008
Fmt 4701
Sfmt 4702
E:\FR\FM\22FEP2.SGM
22FEP2
Federal Register / Vol. 87, No. 35 / Tuesday, February 22, 2022 / Proposed Rules
lotter on DSK11XQN23PROD with PROPOSALS2
MI. ADEQ used the National Oceanic
and Atmospheric Administration
(NOAA) HYbrid Single Particle
Lagrangian Integrated Trajectory
(HYSPLIT) 34 model to evaluate wind
back trajectories from over a 10-year
period (2008–2017).35 Over the course
of the 10-year period, ADEQ identified
95 elevated ozone days (MDA8 > 70.9
ppb) for the Allegan County, MI
monitor.36 Next, ADEQ identified the
maximum ozone value within these
elevated ozone days.37 Using HYSPLIT,
ADEQ ran 72-hour back trajectories
using the hour of the maximum ozone
value for each elevated day as the back
trajectory start time. To consider the
effects of vertical variations in wind
flows on transport patterns, ADEQ used
the following starting heights above
ground level: 100m, 500m, 1000m, and
1500m. ADEQ obtained 40 km grid
meteorological data for the back
trajectory analysis using Eta Data
Assimilation System (EDAS) data.38 In
total, ADEQ ran 152 back trajectories for
each mixing height.39 ADEQ filtered the
back trajectories to determine whether
further analysis is warranted using two
criteria. First, ADEQ filtered out back
trajectories that had a starting hour
mixing height below the back trajectory
start height because ADEQ asserted
these air parcels would not have
reached ambient air 40 at the Allegan
34 HYbrid Single-Particle Lagrangian Integrated
Trajectory (HYSPLIT) model is a complete system
for computing both simple air parcel trajectories
and complex dispersion and deposition
simulations. The model is designed to support a
wide range of simulations related to the
atmospheric transport and dispersion of pollutants
and hazardous materials to the Earth’s surface.
35 ADEQ analyzed ten years of HYSPLIT back
trajectories to examine potential relationships
between elevated ozone days at the Allegan County,
MI monitor and emissions from Arkansas. In the
SIP submission ADEQ stated their rationale for
looking at an extended period of time is to gain a
more complete picture of how Arkansas’s emissions
might contribute to elevated ozone in Allegan
County, MI, rather than relying entirely on the
EPA’s modeling simulation, which is based on a
single base year.
36 See the AirNow-Tech website at https://
www.airnowtech.org/. AirNow-Tech is a website for
air quality data management analysis, and decision
support used by the Federal, State, Tribal, and local
air quality organizations.
37 If the same maximum eight-hour value
occurred multiple times a day, ADEQ evaluated all
incidences of the value for that day.
38 EDAS is an intermittent data assimilation
system that uses successive three-hour model
forecasts to generate gridded meteorological fields
that reflect observations covering the continental
United States. EDAS is accessible at https://
ready.arl.noaa.gov/edas40.php.
39 Mixing heights (m), defined as the height above
ground level of the layer adjacent to the ground
over which an emitted or entrained inert nonbuoyant tracer will be mixed by turbulence.
40 Ambient air is the ‘‘portion of the atmosphere,
external to buildings, to which the general public
has access.’’ 40 CFR 50.1(e).
VerDate Sep<11>2014
20:06 Feb 18, 2022
Jkt 256001
County, MI monitor site. Second, ADEQ
filtered out any back trajectory that did
not have a path through any portion of
Arkansas. After ADEQ applied their
filter criteria, 41 out of 608 back
trajectories (6.74%) remained from 22
out of the 95 elevated ozone days (23%)
examined. Of the 10 years examined,
ADEQ also found that air passing
through Arkansas only reached Allegan
County, MI on four or more days in one
year: 2012.41 For 2012, HYSPLIT
analyses indicated 14 Arkansas-Allegan
County, MI linked back trajectories for
7 days in total in 2012, whereas for
2011, 2013, 2014, and 2016 the
HYSPLIT analyses indicated three, two,
zero and one days with ArkansasAllegan County, MI linked back
trajectories, respectively. For the 10
years ADEQ’s performed HYSPLITs,
ADEQ’s HYSPLIT analysis indicated on
average 2.2 days per year had
trajectories with Arkansas-Allegan
County, MI linked back trajectories.
ADEQ also noted that these trajectories
passed through other states and through
Metropolitan Statistical Areas (MSAs) 42
both before and after traversing through
Arkansas. Specifically, ADEQ stated
that 37 trajectories passed through the
Chicago-Naperville-Elgin, IL–IN–WI
MSA prior to reaching Allegan County,
MI. Based on these results, ADEQ
concluded that other states and MSAs
were more likely to have influenced
ozone concentrations at the Allegan
County, MI monitor on the days with
back trajectories linked to Arkansas.
In Step 3, ADEQ also considered air
quality trends in Allegan County, MI,
emission trends in other upwind states,
relative contribution from other upwind
states, and cost factors. ADEQ presented
that ozone DVs in Allegan County, MI
fluctuated over the 2008–2017 period
with higher concentration occurring
from 2012 through 2014 but declining
since 2014. ADEQ also mentioned that
despite the most recent 2017 DV for the
Allegan County monitor continuing to
show an exceedance of the 2015 ozone
NAAQS, the EPA-projected 2023 ozone
average DV at the Allegan County, MI
monitor, based on data provided in the
March 2018 memorandum, is 69.0 ppb,
which would be in attainment of the
2015 ozone NAAQS in 2023.
Next, ADEQ included an evaluation of
the relative contribution and the
41 The number of days in a given year and the
number of consecutive years is of particular
relevance for the ozone NAAQS, which is
calculated based the annual fourth-highest daily
maximum eight-hour concentration averaged over
three consecutive years.
42 MSA is defined as a geographic region with a
high population density at its core and close
economic ties throughout the area.
PO 00000
Frm 00009
Fmt 4701
Sfmt 4702
9805
emission trends from the eight states 43
with contributions greater than 1 ppb to
the Allegan County, MI receptor. The
emission trends evaluation examined
ozone precursors, nitrogen oxides (NOX)
and volatile organic compounds (VOC),
from 2011 to 2017 and the model
projected fy 2023 emissions level.
ADEQ noted that the two states with the
highest contributions to Allegan County,
MI—Illinois and Indiana—have both
experienced year-over-year decreases in
NOX emissions in excess of 20,000 tons
of NOX reduced per year. Arkansas had
also experienced decreases in NOX
emissions each evaluated year and
emitted less NOX than any other of the
potentially linked states. In addition,
ADEQ referenced the EPA projections
showing that most potentially linked
states will continue to realize reductions
in NOX, as well as VOCs, through 2023.
ADEQ confirmed that based on this
analysis, the overall general trends of
NOX and VOC emissions are declining
from Arkansas and the other linked
states. The continuation of trends in the
emissions reductions observed,
particularly from Illinois and Indiana,
are anticipated by ADEQ to result in air
quality improvements in Allegan
County, MI.
In terms of cost analysis, ADEQ
focused only on the cost of NOX
controls at electric generating units
(EGUs) in the State because EGUs are
the largest source of NOX emissions that
ADEQ regulates. In its analysis, ADEQ
found that the costs to install additional
NOX controls (selective catalytic
reduction, SCR and selective
noncatalytic reduction, SNCR) at EGUs
exceed the EPA’s cost thresholds used
for the CSAPR and CSAPR Update
rules.44 Based on ADEQ’s evaluation of
the evidence, ADEQ concluded that no
additional controls beyond pre-existing
43 The eight linked states include Illinois, 42%;
Indiana, 15%; Michigan, 7%; Missouri, 6%; Texas,
5%; Wisconsin, 4%; Oklahoma, 3% and Arkansas,
4%. The remaining contribution is labeled at
‘‘Other’’. The linkages are based on the EPA’s
modeling results that are attached to the March
2018 memorandum.
44 The EPA’s Revised CSAPR Update, 86 FR
23054 (April 20, 2021), states ‘‘. . . EPA adjusted
its representative cost for optimizing existing SNCR
control to $1,800 per ton in response to comments
received on the proposed rule . . . EPA views
$1,600 per ton for optimization of existing SCR
control and installation of state-of-the are NOX
combustion controls and $1,800 per ton for
optimization of existing SNCRs as comparable for
policy purposes.’’ ADEQ’s screening analysis using
the EPA tools (referencing the EPA’s Air Pollution
Control Cost Estimation Spreadsheet for SCR)
shows that cost-effectiveness values for ozoneseason operation of SCR and SNCR are: $12,605–
$31,580/ton for SCR and $4,221–$45,581 for SNCR.
ADEQ notes that any costs imposed to install
controls at the examined EGUs would be passed on
to Arkansas ratepayers.
E:\FR\FM\22FEP2.SGM
22FEP2
9806
Federal Register / Vol. 87, No. 35 / Tuesday, February 22, 2022 / Proposed Rules
state and Federal regulations were
warranted for Arkansas sources to
satisfy interstate transport obligations
for the 2015 ozone NAAQS.
Based on the determinations made by
ADEQ at Steps 1 through 3, ADEQ did
not include any new control measures
in the SIP submission to reduce ozone
precursor emissions as part of a Step 4
analysis.
lotter on DSK11XQN23PROD with PROPOSALS2
B. EPA Evaluation of the ADEQ SIP
Submission
The EPA is proposing to find that
ADEQ’s October 10, 2019, SIP
submission does not meet the State’s
obligations with respect to prohibiting
emissions that contribute significantly
to nonattainment or interfere with
maintenance of the 2015 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 ADEQ’s SIP
submission.
1. Evaluation of Information Provided
by ADEQ Regarding Step 1
At Step 1 of the 4-Step framework,
ADEQ relied on the EPA modeling
released in the March 2018
memorandum to identify nonattainment
and maintenance receptors in 2023. As
described in Section I of this action, the
EPA has recently performed updated
modeling using the 2016v2 platform to
evaluate interstate transport of ozone for
a fy 2023.45 The EPA proposes to
primarily rely on the EPA’s modeling
using the 2016v2 platform (EPA 2016v2
modeling), to identify projected
nonattainment and maintenance
receptors in fy 2023. Updating the base
period from 2011 (base period used in
data included in the March 2018
memorandum) to a more recent year
(2016) allows for better projections of
which monitors will have problems
attaining and/or maintaining the 2015
ozone NAAQS and factors in more
recent base year DVs. The EPA notes
that with a switch from 2011 base
period meteorology to 2016 base period
meteorology, it is normal and expected
that the potential downwind
nonattainment or maintenance receptors
would change due to the different
weather patterns that occurred in the
different base periods, which impacts
both the transport of pollutants from
upwind states and what receptors have
45 Per the instructions in the Supplementary
Information section above, all public comments,
including comments on the EPA’s air quality
modeling should be submitted in the Regional
docket for this action, Docket ID No. EPA–R06–
OAR–2021–0801. Comments are not being accepted
in Docket No. EPA–HQ–OAR–2021–0663.
VerDate Sep<11>2014
20:06 Feb 18, 2022
Jkt 256001
higher monitored values within
nonattainment/maintenance regions.46
Modeling using both the 2011 and 2016
based years consistently project that
certain areas will have problems
attaining and/or maintaining the 2015
ozone NAAQS including receptors in
Texas.
2. Evaluation of Information Provided
by ADEQ Regarding Step 2
As noted earlier, ADEQ utilized a 1
ppb threshold at Step 2 to identify
whether the State was ‘‘linked’’ to a
projected downwind nonattainment or
maintenance receptor. ADEQ identified
linkages for Arkansas to one 2023
projected maintenance receptor, Allegan
County, MI, and no 2023 projected
nonattainment receptors.
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 as an alternative to a 1 percent
threshold, at Step 2 of the 4-Step
interstate transport framework, for the
purposes of identifying linkages to
downwind receptors. However, the
EPA’s August 2018 memorandum
provided that whether or not a 1 ppb
threshold is appropriate must be based
on an evaluation of state-specific
circumstances, and no such evaluation
was included in the state’s submittal.
Instead, ADEQ cited to the EPA’s SILs
Guidance as a basis to support the use
of a 1 ppb threshold; however, ADEQ
did not explain the relevance of the SILs
Guidance to ADEQ’s statutory obligation
under the interstate transport provision.
The SILs Guidance relates to a different
provision of the Clean Air Act regarding
implementation of the prevention of
significant deterioration (PSD)
permitting program, i.e., a program that
applies in areas that have been
designated attainment of the NAAQS.
The SILs Guidance is not applicable to
46 We note that ADEQ identified additional
modeling performed by TCEQ and Midwest Ozone
Group, but simply concluded that different
modeling can lead to differences in DV projections
and ozone contributions of these two alternative
modeling analyses, only TCEQ’s modeling using a
2012 base year identified receptors in Texas that
projected different DVs for the Texas receptors
identified in the EPA’s 2011 base year. We discuss
the EPA’s review of the TCEQ’s modeling elsewhere
in this action and the Technical Support Document
for this action ‘‘EPA Region 6 2015 8-Hour Ozone
Transport SIP Proposal Technical Support
Document’’ (EPA Region 6 2015 Ozone Transport
SIP TSD.pdf) included in the Regional docket for
this action (Docket ID No. EPA–R06–OAR–2021–
0801), but we do conclude that TCEQ and recent
monitoring data indicate that there are problematic
receptors that are expected to be either
nonattainment or maintenance receptors in 2023
including the Texas receptors that the EPA
identified in our March 2018 memorandum with
Arkansas linkages.
PO 00000
Frm 00010
Fmt 4701
Sfmt 4702
the interstate transport provision, which
requires states to eliminate significant
contribution or interference with
maintenance of the NAAQS at known
and ongoing air quality problem areas in
other states. The EPA does not, in this
action, agree that the State has justified
its application of the 1 ppb threshold. In
any case, both the EPA’s most recent
modeling, EPA 2016v2 modeling, and
the modeling relied on by ADEQ in its
SIP submittal, indicate that the State is
projected to contribute greater than both
the 1 percent and alternative 1 ppb
thresholds. While the EPA does not, in
this action, propose to 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, (as shown in
Table AR–2) the State’s use of this
alternative threshold at Step 2 of the 4Step interstate framework would not
alter our review and proposed
disapproval of this SIP submittal.
Additionally, 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 threshold
at Step 2. (The memorandum also
indicated that any higher alternative
threshold, such as 2 ppb, would likely
not be appropriate.) However, the EPA
also provided that ‘‘air agencies should
consider whether the recommendations
in this guidance are appropriate for each
situation.’’ Following receipt and review
of 49 interstate transport SIP submittals
for the 2015 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
E:\FR\FM\22FEP2.SGM
22FEP2
Federal Register / Vol. 87, No. 35 / Tuesday, February 22, 2022 / Proposed Rules
lotter on DSK11XQN23PROD with PROPOSALS2
support approval.47 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.
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.48
The availability of different thresholds
at Step 2 has the potential to result in
inconsistent application of interstate
transport 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 interstate transport
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 would 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
47 ‘‘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 comments on this proposed approval and
has not taken final action with respect to this
proposal.
48 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.
VerDate Sep<11>2014
20:06 Feb 18, 2022
Jkt 256001
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 memorandum that there
was some similarity in the amount of
total upwind contribution captured (on
a nationwide basis) between 1 percent
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; 49 in
EPA 2016v2 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 memorandum
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
basis for the EPA’s proposed
disapproval of ADEQ’s SIP submission
with respect to the Step 2 analysis is, in
the Agency’s view, warranted even
under the terms of the August 2018
49 See
PO 00000
August 2018 memorandum, at page 4.
Frm 00011
Fmt 4701
Sfmt 4702
9807
memorandum. The EPA invites
comment on this broader discussion of
issues associated with alternative
thresholds at Step 2. (See
Supplementary Information section
above for details and docket to submit
comments). Depending on public
comments received in relation to this
action and further evaluation of this
issue, the EPA may determine to rescind
the 2018 memorandum in the future.
ADEQ included information in its SIP
submission regarding back trajectories,
emissions trends, and EGU cost controls
to conclude that emissions from
Arkansas should not be considered to
contribute significantly to
nonattainment or interfere with
maintenance of the NAAQS in other
states because there is not a persistent
and consistent pattern of contribution
from the State. While it is not entirely
clear whether ADEQ was analyzing
these factors under Step 2 or Step 3, the
EPA is evaluating such arguments under
Step 3, as we view these statements in
the SIP submission to speak to whether
or not a contribution is ‘‘significant’’
once a linkage is established.
3. Results of the EPA’s Step 1 and Step
2 Modeling and Findings for Arkansas
As described in Section I of this
action, the EPA performed air quality
modeling using the 2016v2 emissions
platform to project DVs and
contributions for 2023 (EPA 2016v2
modeling). This data was examined to
determine if Arkansas contributes at or
above the threshold of 1 percent of the
2015 ozone NAAQS (0.70 ppb) to any
downwind nonattainment or
maintenance receptor. As shown in
Table AR–2, the data 50 indicate that in
2023, emissions from Arkansas
contribute greater than 1 percent of the
standards to nonattainment or
maintenance-only receptors in Texas:
Denton County (Monitor ID.
481210034), Brazoria County (Monitor
ID. 480391004), Harris County (Monitor
ID. 482010055, Monitor ID. 482011034,
50 Design values and contributions at individual
monitoring sites nationwide are provided in the
file: 2016v2_DVs_state_contributions.xlsx which is
included in docket ID No. EPA–HQ–OAR–2021–
0663.
E:\FR\FM\22FEP2.SGM
22FEP2
9808
Federal Register / Vol. 87, No. 35 / Tuesday, February 22, 2022 / Proposed Rules
and Monitor ID. 482011035).51 52
Therefore, based on the EPA’s
evaluation of the information submitted
by ADEQ, and based on the EPA model
2016v2 results for 2023, the EPA
proposes to find that Arkansas is linked
at Steps 1 and 2 and has an obligation
to assess potential emissions reductions
from sources or other emissions activity
at Step 3 of the 4-Step framework.
TABLE AR–2—PROJECTED NONATTAINMENT AND MAINTENANCE RECEPTORS WITH ARKANSAS LINKAGES IN 2023 BASED
ON EPA 2016V2 MODELING
Receptor
(site ID, county, state)
lotter on DSK11XQN23PROD with PROPOSALS2
481210034,
480391004,
482010055,
482011034,
482011035,
2023
average DV
(ppb)
Nonattainment/
maintenance
Denton, TX ................................
Brazoria, TX ..............................
Harris, TX ..................................
Harris, TX ..................................
Harris, TX ..................................
Maintenance .....................................................
Maintenance .....................................................
Nonattainment ..................................................
Maintenance .....................................................
Maintenance .....................................................
70.4
70.1
71.0
70.3
68.0
2023
maximum DV
(ppb)
72.2
72.3
72.0
71.6
71.6
Arkansas
contribution
(ppb)
0.76
1.39
1.00
1.38
1.34
We recognize that the results of the
EPA modeling released in the March
2018 memorandum (2011 base year) and
the EPA 2016v2 modeling (2016 base
year) identified different receptors and
linkages at Steps 1 and 2 of the 4-Step
framework. These differing results about
receptors and linkages can be affected
by the varying meteorology from year to
year, but we do not think the differing
results mean that the modeling or the
EPA methodology for identifying
receptors or linkages is inherently
unreliable. Rather, these separate
modeling runs indicated (1) that there
were receptors that would struggle with
nonattainment or maintenance in the
future, and (2) that Arkansas was linked
to some set of these receptors, even if
the receptors and linkages differed from
one another in their specifics (e.g., a
different set of receptors were identified
to have nonattainment or maintenance
problems, or Arkansas was linked to
different receptors in one modeling run
versus another). We think this common
result indicates that Arkansas’s
emissions were substantial enough to
generate linkages at Steps 1 and 2 to
some set of downwind receptors, under
varying assumptions and meteorological
conditions, even if the precise set of
linkages changed between modeling
runs. Under these circumstances, we
think it is appropriate to proceed to a
Step 3 analysis to determine what
portion of Arkansas’s emissions should
be deemed ‘‘significant.’’ In doing so,
we are not considering our own earlier
modeling results included in EPA’s
March 2018 memorandum to be of equal
reliability relative to more recent EPA
2016v2 modeling. However, where
alternative or older modeling generated
linkages, even if those linkages differ
from linkages in EPA 2016v2 modeling,
that information provides further
evidence, not less, in support of a
conclusion that the state is required to
proceed to Step 3 to further evaluate its
emissions.
At Step 3 of the 4-Step 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
contribute significantly to
nonattainment or interfere with
maintenance and, thus, must be
eliminated under CAA section
110(a)(2)(D)(i)(I).
ADEQ included in their SIP
submission a further analysis of its
modeled linkage to Allegan, MI (the
only linked receptor it analyzed, based
on its application of a 1 ppb threshold).
Arkansas stated that the purpose and its
conclusion of this analysis was that it
would not contribute significantly to the
Allegan, MI monitor because the state’s
emissions did not result in a consistent
and persistent pattern of ozone
contribution. As stated earlier, EPA
2016v2 modeling projects that the
Allegan County, MI receptor will be
attaining and is not expected to have
difficulty maintaining the standard in
2023. As such, the EPA is not relying on
the comparative analysis of emissions
trends that ADEQ provided in order to
conclude that Arkansas’s emissions do
not contribute significantly to a
nonattainment or maintenance problem
in Allegan, MI. We note however, that
ADEQ’s SIP submission and response to
comments do not clearly define what
ADEQ considers to be persistent and
consistent pattern of contribution.
Rather, the SIP submission simply states
that contribution should be deemed
‘‘significant’’ only if there is a persistent
and consistent pattern of several days
with elevated ozone.
To be clear, the modeling establishing
linkages of Arkansas to downwind
nonattainment and maintenance
receptors already establishes that there
is a consistent and persistent pattern of
contribution on elevated ozone days
from Arkansas to other states. That is
because EPA’s methodology for
projecting future year ozone
concentrations accounts for precisely
these concerns—the relative response
factor 53 that is applied to historic
monitored data to generate projections
is calculated by looking only at days
with elevated ozone levels (ten days is
preferred with a minimum of five days).
The EPA notes that monitored
attainment with the ozone standard is
determined by averaging the fourth high
value recorded each year for three years.
So, the EPA believes it is important to
51 These modeling results are consistent with the
results of a prior round of 2023 modeling using the
2016v1 emissions platform which became available
to the public in the fall of 2020 in the Revised
CSAPR Update, as noted in Section I of this action.
That modeling showed that Arkansas had a
maximum contribution greater than 0.70 ppb to at
least one nonattainment or maintenance-only
receptor in 2023. These modeling results are
included in the file ‘‘Ozone Design Values And
Contributions Revised CSAPR Update.xlsx’’ in
docket EPA–HQ–OAR–2021–0663.
52 Allegan County Monitor ID. 260050003 is not
a receptor in 2023 in the EPA 2016v2 modeling.
2023 avg DV is 67.3 ppb and 2023 Max. DV is 68.4
ppb, so the Allegan County monitor is not a
receptor in 2023 for nonattainment or maintenance.
53 The relative response factor (RRF) is a ratio
developed using the modeled changes between the
base case and future case for high ozone modeled
days. Typically, the 10 highest MDA8 modeled days
in the base case are found and the maximum value
from the 3x3 grid centered on the monitor for each
day is used to calculate a 10-day average base case
modeled value. Then a similar concentration
average is developed for same 10 base case days and
the same grid cell that provided the base case
concentration to calculate a future year 10-day
average modeled value using the future year
modeling results. The RRF is then calculated by
using this future year 10-day average model value
divided by the base case year 10-day average model
value to develop a ratio representing the change in
modeled ozone. The RRF is then multiplied times
the base DV value to result in a projected future
year DV.
VerDate Sep<11>2014
20:06 Feb 18, 2022
Jkt 256001
4. Evaluation of Information Provided
by ADEQ Regarding Step 3
PO 00000
Frm 00012
Fmt 4701
Sfmt 4702
E:\FR\FM\22FEP2.SGM
22FEP2
lotter on DSK11XQN23PROD with PROPOSALS2
Federal Register / Vol. 87, No. 35 / Tuesday, February 22, 2022 / Proposed Rules
estimate impacts on the days with
highest projected ozone levels. The
EPA’s approach, as detailed in the Air
Quality Modeling Technical Support
Document for 2015 Ozone NAAQS
Transport SIP Proposed Actions
included in Docket ID No. EPA–HQ–
OAR–2021–0663, does this by
estimating the average fy 2023 impact
from an upwind state on the days with
the highest projected ozone levels at the
downwind nonattainment or
maintenance receptor. The days chosen
to analyze the future impacts are chosen
initially by the selecting the ten highest
days in the base period modeling that
are projected to be above 65 ppb in the
base period. If there are not ten days
above 65 ppb at a potential receptor, the
number of days above 65 ppb are used
as long as there is at least five days
above 65 ppb in the base period. If the
air quality modeling shows fewer than
five days above 65 ppb in the base
period, then the data for impacts at that
receptor in fy 2023 are not calculated.
The base and future year modeling for
these five to ten days is then used to
project fy 2023 ozone DVs to determine
whether it is projected to be a
nonattainment or maintenance receptor
in 2023. For the same five to ten days
identified, the future year modeling
provides the estimated daily
contribution at a potential receptor’s
future year daily MDA8 and these daily
contributions are averaged for the five to
ten days to result in the average
contribution from the upwind area.
As mentioned previously, ADEQ used
HYSPLIT back trajectories to assess
wind patterns on elevated ozone days in
an attempt to demonstrate that there is
not persistent and consistent pattern of
contribution from Arkansas to the
Allegan County, MI receptor. HYSPLIT
back trajectory analyses use archived
meteorological modeling that includes
actual observed data (surface, upper air,
airplane data, etc.) and modeled
meteorological fields to estimate the
most likely route of an air parcel
transported to a receptor at a specified
time. The method essentially follows a
parcel of air backward in hourly steps
for a specified length of time. HYSPLIT
estimates the central path in both the
vertical and horizontal planes. The
HYSPLIT central path represents the
centerline with the understanding that
there are areas on each side horizontally
and vertically that also contribute to the
concentration at the end point monitor.
The horizontal and vertical areas that
potentially contribute to the end point
concentration grow wider from the
centerline the further back in time the
trajectory goes. Therefore, a HYSPLIT
VerDate Sep<11>2014
20:06 Feb 18, 2022
Jkt 256001
centerline does not have to pass directly
over emissions sources or emission
source areas but merely relatively near
emission source areas for those areas to
contribute to concentrations at the
endpoint. The EPA relies on back
trajectory analysis as a corollary
analysis along with observation-based
meteorological wind fields at multiple
heights to examine the general
plausibility of the photochemical model
‘‘linkages.’’ Since the back trajectory
calculations do not account for any air
pollution formation, dispersion,
transformation, or removal processes as
influenced by emissions, chemistry,
deposition, etc., the trajectories cannot
be used to develop quantitative
contributions. Therefore, back
trajectories cannot be used to
quantitatively evaluate the magnitude of
the existing photochemical
contributions from upwind states to
downwind receptors. Chemical
transport models, such as the one relied
upon by Arkansas to establish the
linkage between Arkansas and those
downwind receptors in the first
instance, do take these factors into
account and therefore provide a more
robust assessment of ozone
contribution.
During ADEQ’s public comment
period, the EPA submitted comments
noting concerns regarding the
methodology ADEQ used in their
HYSPLIT back trajectories analysis.54
While we are not providing a detailed
evaluation of ADEQ’s HYSPLIT analysis
in this rulemaking, we do note that our
review identified a number of concerns
with how ADEQ screened out a number
of back trajectories, which invalidates
ADEQ’s conclusions.55 While we
disagree with ADEQ’s methodologies
and conclusions, we note that ADEQ’s
54 The EPA reviewed the ADEQ SIP submission
and provided comments during the State’s public
comment period for the proposed SIP action. The
EPA’s comment letter and ADEQ’s response to
comments are included in ADEQ’s October 19,
2019, SIP submission, which is available in the
Regional docket for this action (Docket ID No. EPA–
R06–OAR–2021–0801).
55 Concerns included removing of HYSPLIT back
trajectories based on start height, the start time that
Arkansas used for the back trajectories and
removing of back trajectories when the centerline
passed near but not through Arkansas because
Arkansas has some very large point sources near the
Arkansas state line that could be contributing.
Texas also screened their HYPSLIT back trajectories
similarly to Arkansas and we have further
discussed our concerns and why such screening
invalidates conclusions from the HYSPLIT back
trajectory analyses. See EPA’s review and
conclusions in discussion of TCEQ’s HYSPLIT
analyses in the ‘‘EPA Region 6 2015 8-Hour Ozone
Transport SIP Proposal Technical Support
Document’’ (EPA Region 6 2015 Ozone Transport
SIP TSD.pdf) included in the Regional docket for
this action (Docket ID No. EPA–R06–OAR–2021–
0801).
PO 00000
Frm 00013
Fmt 4701
Sfmt 4702
9809
HYSPLIT back trajectory information
did not show that the base years used
in the EPA modeling (2011 and 2016)
demonstrated an unusual amount of
transport of air parcels from Arkansas to
nonattainment or maintenance receptors
in downwind states (i.e., the modeling
years used by the EPA do not skew the
results toward finding linkages).56
Therefore, although Arkansas asserted
that its additional air quality factor
analysis using back trajectory analysis is
a permissible way to interpret which
contributions are ‘‘significant’’ because
that analysis examines whether there
was a ‘‘persistent and consistent pattern
of contribution on several days with
elevated ozone,’’ the modeled linkage at
Step 2 is a superior approach for
assessing the persistence of a state’s
contribution. It is superior because it is
based on the average of the
contributions on the five to ten highest
ozone days. Considering the form of the
standard, this is a sufficient number of
days to determine if an impact is
persistent enough to impact an area’s
ability to attain or maintain the
standard. The modeling is also a better
method because it accounts for
dispersion while back trajectory
analysis as performed by Arkansas only
shows the centerline of air parcel travel
and otherwise will leave out days when
Arkansas would have contributed to
downwind problems. Finally, because
the modeling accounts for dispersion
and chemical reactions, it can provide a
quantitative estimate of contribution.
ADEQ also contested the significance
of its modeled contribution above 1 ppb
based on the relatively larger
contributions of other upwind states to
the receptor to which it was linked. The
EPA disagrees that a state’s small
contribution relative to other upwind
states is a permissible basis for finding
no obligation under the interstate
transport provision. CAA
110(a)(2)(D)(i)(I) requires states and the
EPA to address interstate transport of air
pollution that contributes to downwind
states’ ability to attain and maintain the
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
an upwind state is significantly
contributing to that problem. States are
not obligated under CAA section
110(a)(2)(D)(i)(I) to reduce emissions
sufficient on their own to resolve
56 ADEQ’s summary of trajectories indicated that
2011 had three linked back trajectories and 2016
had one linked back trajectories and the EPA
calculated the average for 2008–2017 in ADEQ’s
table was 2.2 linked back trajectories per year.
E:\FR\FM\22FEP2.SGM
22FEP2
lotter on DSK11XQN23PROD with PROPOSALS2
9810
Federal Register / Vol. 87, No. 35 / Tuesday, February 22, 2022 / Proposed Rules
downwind receptors’ nonattainment or
maintenance problems. Rather, states
are obligated to eliminate their 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 arguments
suggesting that upwind states should be
excused from interstate transport
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
these 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
emissions from other states also
contribute some amount of pollution to
the same receptors to which the state is
linked.
ADEQ did not provide additional
analysis for other receptors to which it
was linked above 1 percent in the air
quality modeling upon which it relied,
and to which it continues to be linked
in EPA 2016v2 modeling. To effectively
evaluate 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
VerDate Sep<11>2014
20:06 Feb 18, 2022
Jkt 256001
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. As discussed below, ADEQ
did not conduct an adequate analysis in
their SIP submission. We therefore
propose that ADEQ 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 Arkansas failed to adequately
do so.
In analyzing potential additional NOX
controls, ADEQ found that additional
controls on its EGUs would exceed the
cost-effectiveness thresholds identified
in the CSAPR and CSAPR Update rules.
For the cost analysis, Arkansas only
focused on the potential costs of NOX
controls for EGUs. As stated above,
Arkansas found that the costs to install
additional NOX controls (selective
catalytic reduction, SCR, and selective
noncatalytic reduction, SNCR) at
electric generating units (EGUs) exceed
EPA’s cost thresholds used for the
CSAPR and CSAPR Update rules. Based
on the projected cost of these controls
relative to the thresholds used in those
two prior EPA rules, Arkansas
concluded that no new controls beyond
those Federal and State regulations
already in existence were cost-effective,
especially considering that Allegan
County, MI is projected to be in
attainment with the 2015 ozone NAAQS
PO 00000
Frm 00014
Fmt 4701
Sfmt 4702
and Arkansas’s small contribution
relative to other states potentially linked
to Allegan County, MI based on EPA’s
modeling.
Arkansas’s analysis is inadequate
because its focus is only on EGUs.57 See
Wisconsin, 938 F.3d at 318–20. We also
find Arkansas’s conclusions as to the
availability of cost-effective controls for
EGUs to be inadequate. Relying on the
CSAPR Update’s (or any other CAA
program’s) determination of costeffectiveness without further Step 3
analysis is not approvable. Costeffectiveness must be assessed in the
context of the specific CAA program;
assessing cost-effectiveness in the
context of ozone transport should reflect
a more comprehensive evaluation of the
nature of the interstate transport
problem, the total emissions reductions
available at several cost thresholds, and
the potential air quality impacts of those
reductions at downwind receptors.
While the EPA has not established a
benchmark cost-effectiveness value for
2015 ozone NAAQS interstate transport
obligations, because the 2015 ozone
NAAQS is a more stringent and more
protective air quality standard, it is
reasonable to expect control measures or
strategies to address interstate transport
under this NAAQS to reflect higher
marginal control costs. ADEQ’s
submission failed to provide a
justification for why the $1400/ton
threshold used in the CSAPR Update is
appropriate to rely on for the 2015
ozone NAAQS. ADEQ’s analysis does
not consider any air quality impacts of
assessed controls at downwind
receptors. As stated above, assessing
cost-effectiveness in the context of
ozone transport requires more than just
assessing the cost of controls per ton of
NOX removed. As such, ADEQ’s
assessment of the cost of controls and
reliance on the marginal cost threshold
of $1,400/ton used for the CSAPR
Update is inadequate. Furthermore, EPA
2016v2 modeling captures all existing
CSAPR trading programs in the baseline
and confirms that these control
programs were not sufficient to
eliminate Arkansas’s linkage at Steps 1
and 2 under the 2015 ozone NAAQS.
The State was therefore obligated at
Step 3 to assess additional control
measures using a multifactor analysis.
57 In 2017, National Emission Inventory (NEI)
NOX emissions from EGU sources represent 56%
percent of the total NOx emissions categories in
Arkansas that report emissions to the NEI. See AR
NOx.xlsx datasheet included in the Regional docket
for this action (Docket ID No. EPA–R06–OAR–
2021–0801).
E:\FR\FM\22FEP2.SGM
22FEP2
Federal Register / Vol. 87, No. 35 / Tuesday, February 22, 2022 / Proposed Rules
5. Evaluation of Information Provided
by ADEQ Regarding Step 4
Step 4 of the 4-Step interstate
transport framework calls for the
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. ADEQ’s
SIP submission, which looked only at
additional NOX controls at EGUs and
dismissed such controls as not costeffective relative to the thresholds
established in earlier EPA transport
rules, did not constitute an adequate
emission reduction analysis at Step 3.
Based on its conclusions, ADEQ did not
revise its SIP to include any emission
reductions. As a result, the EPA
proposes to disapprove ADEQ’s
submittal on the separate, additional
basis that Arkansas has not developed
or included permanent and enforceable
emissions reductions in its SIP
necessary to meet the obligations of
CAA section 110(a)(2)(D)(i)(I).
6. Conclusion
Based on the EPA’s evaluation of
ADEQ’s SIP submission, the EPA is
proposing to find that ADEQ’s October
19, 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
ozone NAAQS in any other state.
III. Louisiana SIP Submission
Addressing Interstate Transport of Air
Pollution for the 2015 Ozone NAAQS
and the EPA Evaluation of the SIP
Submission
A. Summary of LDEQ SIP Submission
Addressing Interstate Transport of Air
Pollution for the 2015 Ozone NAAQS
On November 13, 2019, the Louisiana
Department of Environmental Quality
(LDEQ) made a SIP submission
addressing the State of Louisiana’s
interstate transport of air pollution for
the 2015 ozone NAAQS. The SIP
submission provided LDEQ’s analysis of
Louisiana’s impact to downwind states
and concluded that emissions from
Louisiana will not contribute
significantly to nonattainment or
interfere with maintenance of the 2015
ozone NAAQS in other states.
The LDEQ’s SIP submission provided
an analysis of Louisiana’s air emissions
impact to downwind states using a 3Step alternative framework similar to
the EPA’s 4-Step framework. LDEQ’s 3Step alternative framework includes:
Step 1: Identify monitors projected to be
in nonattainment or have maintenance
issues in a future year; Step 2: Identify
projected nonattainment and/or
maintenance monitors in other states
that might be impacted by emissions
from Louisiana, tagging them for further
review; and, Step 3: Determine if
emissions from Louisiana contribute
significantly to nonattainment or
interfere with maintenance at the
monitors tagged for review in Step 2.
LDEQ noted that its Step 1 is identical
to the EPA’s Step 1, and its Steps 2 and
3 are equivalent to the EPA’s Step 2.
Louisiana further noted that Steps 3 and
4 of the EPA’s 4-Step framework are
relevant only if emissions from
Louisiana contribute significantly to
nonattainment or interfere with
maintenance at downwind monitors in
another state.
LDEQ’s Step 1 was to identify
downwind monitors projected to be in
nonattainment and/or have maintenance
issues in future year 2023 (fy 2023). At
this step, LDEQ relied on the EPA’s
interstate transport modeling results
that are included as an attachment to
the March 2018 memorandum. The EPA
March 2018 modeling results provided:
(1) Projected average DV and maximum
DV for 2023 for the ozone monitors (or
‘‘receptors’’) in the 48 contiguous states
and (2) the expected contribution of
9811
state emissions to the projected ozone
concentrations at each ozone monitor.
LDEQ used a contribution threshold
of 1 ppb in LDEQ’s Step 2 to identify
projected nonattainment and/or
maintenance receptors in other states
that might be impacted by emissions
from Louisiana and tagged them for
further review. To support a 1 ppb
contribution threshold, LDEQ’s
submission stated that a 1 percent
threshold is inappropriate because that
value is not detectable by a monitor and
the value of 1 percent of the 2015 ozone
NAAQS would be truncated to zero if
calculated in accordance with the
method for determining DVs for the
ozone NAAQS. LDEQ also stated that
the more stringent threshold of 1
percent of the NAAQS (0.7 ppb) is an
order of magnitude smaller than the
biases and errors typically documented
for regional photochemical modeling.58
Based on LDEQ’s approach of evaluating
linkages at the 1 ppb threshold, five
Texas receptors were identified by
Louisiana for analysis. The Texas
receptors and corresponding receptor
data presented in Louisiana’s SIP are
summarized further in this notice in
Table LA–1.59 The March 2018
memorandum identified monitors in
Allegan, Michigan and Milwaukee and
Sheboygan, Wisconsin as potential
nonattainment and maintenance-only
receptors linked to emissions from
Louisiana based on 1 percent of the
NAAQS threshold. However, Louisiana
did not include the Allegan, Michigan
and Milwaukee and Sheboygan,
Wisconsin receptors in the State’s
analysis because the March 2018
memorandum shows that Louisiana’s
projected modeled contribution values
to each receptor is less than 1 ppb.
TABLE LA–1—PROJECTED NONATTAINMENT AND MAINTENANCE RECEPTORS IDENTIFIED BY LOUISIANA BASED ON THE
EPA’S MARCH 2018 MEMORANDUM
2023
Average DV
(ppb) 60
lotter on DSK11XQN23PROD with PROPOSALS2
Receptor
(site ID, county, state)
480391004, Brazoria, TX .............................................................................................................
58 The Louisiana SIP submittal did not provide a
specific citation to the Simon et al., 2012 reference
to support this assertion. However, we believe the
reference is associated with the following article:
Simon, H., Baker, K.R., Phillips, S., 2012.
‘‘Compilation and interpretation of photochemical
model performance statistics published between
VerDate Sep<11>2014
20:06 Feb 18, 2022
Jkt 256001
2006 and 2012’’. Atmospheric Environment 61,
124–139.
59 The five potential nonattainment and
maintenance receptor monitors identified by LDEQ
are from the Dallas-Fort Worth and HoustonGalveston-Brazoria, TX nonattainment areas for the
PO 00000
Frm 00015
Fmt 4701
Sfmt 4702
74.0
2023
Maximum DV
(ppb) 61
74.9
Louisiana
Contribution
(ppb)
3.80
2015 ozone NAAQS. The Louisiana SIP submittal
appears to have inadvertently omitted Harris
County, TX Monitor ID No. 482011034 for analysis.
EPA’s March 2018 memorandum identified this
monitor as a maintenance receptor with a
contribution of 3.38 ppb from Louisiana emissions.
E:\FR\FM\22FEP2.SGM
22FEP2
9812
Federal Register / Vol. 87, No. 35 / Tuesday, February 22, 2022 / Proposed Rules
TABLE LA–1—PROJECTED NONATTAINMENT AND MAINTENANCE RECEPTORS IDENTIFIED BY LOUISIANA BASED ON THE
EPA’S MARCH 2018 MEMORANDUM—Continued
2023
Average DV
(ppb) 60
Receptor
(site ID, county, state)
482011039,
484392003,
481210034,
482010024,
Harris, TX ................................................................................................................
Tarrant, TX ..............................................................................................................
Denton, TX ..............................................................................................................
Harris, TX ................................................................................................................
lotter on DSK11XQN23PROD with PROPOSALS2
ForLDEQ’s Step 3, Louisiana stated
that an air emission contribution from
the State should only be considered
significant if there is a persistent and
consistent pattern of contribution on
several days with elevated ozone. In
trying to determine whether there is a
persistent and consistent pattern of
contribution, LDEQ analyzed seasonal
weather patterns, surface wind
directions, and periodic back
trajectories. LDEQ used the National
Oceanic and Atmospheric
Administration (NOAA) Hybrid Single
Particle Lagrangian Integrated Trajectory
(HYSPLIT) 62 model to perform 99 back
trajectories for exceedances from the
receptor monitors identified in Table
LA–1 for 2016, 2017, and 2018. Based
on an analysis of the HYSPLIT results,
LDEQ stated that approximately 28% of
the trajectories travel in or through
Louisiana, and only 8% of those back
trajectories originate in the State. The
SIP submission also stated that a
comparison of the EPA’s modeled
contribution between Texas and
Louisiana monitors indicates that a far
greater proportion of the total ozone
detected in Louisiana originates in
Texas rather than vice versa. Therefore,
Louisiana concluded that the impact
from the State’s air emissions was
insignificant to the overall attainment at
the receptor monitors identified in
Table LA–1 and does not significantly
contribute to nonattainment or interfere
with maintenance of the 2015 ozone
NAAQS in other states.
B. EPA Evaluation of the LDEQ SIP
Submission
The EPA is proposing to find that
LDEQ’s November 13, 2019, SIP
submission does not meet the State’s
obligations with respect to prohibiting
emissions that contribute significantly
to nonattainment or interfere with
maintenance of the 2015 NAAQS in any
other state based on the EPA’s
evaluation of the SIP submission using
the 4-Step interstate transport
60 Information added from the EPA’s March 2018
memorandum.
61 Id.
62 See FN 34.
VerDate Sep<11>2014
20:06 Feb 18, 2022
Jkt 256001
framework, and the EPA is therefore
proposing to disapprove Louisiana’s SIP
submission.
1. Evaluation of Information Provided
by LDEQ Regarding Steps 1 and 2
At Step 1 of the 4-Step interstate
transport framework, LDEQ relied on
EPA modeling released in the March
2018 memorandum to identify
nonattainment and maintenance
receptors in 2023. At Step 2 of the
4-Step interstate transport framework,
LDEQ relied on the EPA modeling
released in the March 2018
memorandum to identify upwind state
linkages to nonattainment and
maintenance receptors in 2023. LDEQ
additionally utilized a 1 ppb threshold
at Step 2 to identify 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, as an alternative to a 1
percent threshold, at Step 2 of the
4-Step interstate transport framework,
for the purposes of identifying linkages
to downwind receptors. In any case, the
State is projected to contribute greater
than both the 1 percent and the
alternative 1 ppb thresholds to receptors
in Texas, regardless of whether we look
at LDEQ’s analysis (which relied on the
EPA’s older modeling) or updated
modeling the EPA has performed in
advance of this proposal. As seen in the
tables LA–1 and LA–2, Louisiana
contributes nearly five times the 1 ppb
threshold to nonattainment or
maintenance receptors in Texas.
Therefore, 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
PO 00000
Frm 00016
Fmt 4701
Sfmt 4702
71.8
72.5
69.7
70.4
2023
Maximum DV
(ppb) 61
73.5
74.8
72.0
72.8
Louisiana
Contribution
(ppb)
4.72
1.71
1.92
4.72
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 threshold
at Step 2.63 (The memorandum also
indicated that any higher alternative
threshold, such as 2 ppb, would likely
not be appropriate.) However, the EPA
also provided that ‘‘air agencies should
consider whether the recommendations
in this guidance are appropriate for each
situation.’’ Following receipt and review
of 49 interstate transport SIP submittals
for the 2015 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.64 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.
Furthermore, the EPA’s experience
since 2018 is that allowing for
alternative Step 2 thresholds may be
63 See
August 2018 memorandum, at page 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 comments on this proposed approval and
has not taken final action with respect to this
proposal.
64 ‘‘Air
E:\FR\FM\22FEP2.SGM
22FEP2
Federal Register / Vol. 87, No. 35 / Tuesday, February 22, 2022 / Proposed Rules
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.65
The availability of different thresholds
at Step 2 has the potential to result in
inconsistent application of interstate
transport 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 interstate transport
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 would 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 memorandum that there
was some similarity in the amount of
total upwind contribution captured (on
a nationwide basis) between 1 percent
and 1 ppb. However, the EPA notes that
while this may be true in some sense,
that is not 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; 66 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
9813
particular, a potentially applicable 1
ppb threshold, the EPA’s experience
since the issuance of that memorandum
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
basis for a proposed disapproval of
LDEQ’s SIP submission with respect to
the Step 2 analysis we believe is
warranted under the terms of the August
2018 memorandum. The EPA invites
comment on this broader discussion of
issues associated with alternative
thresholds at Step 2. Depending on
public comments received and further
evaluation of this issue, the EPA may
determine to rescind the 2018
memorandum in the future.
2. Results of the EPA’s Step 1 and Step
2 Modeling and Findings for Louisiana
As described in Section I of this
action, the EPA performed air quality
modeling using the 2016v2 emissions
platform to project DVs and
contributions for 2023.67 This data was
examined to determine if Louisiana
contributes at or above the threshold of
1 percent of the 2015 ozone NAAQS
(0.70 ppb) to any downwind
nonattainment or maintenance receptor.
As shown in Table LA–2, the data 68
indicate that in 2023, emissions from
Louisiana contributed greater than 1
percent of the standards to
nonattainment or maintenance-only
receptors in Texas.69 Therefore, based
on the EPA’s evaluation of the
information submitted by LDEQ, and
based on the EPA’s most recent
modeling results for 2023, the EPA
proposes to find that Louisiana 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.
lotter on DSK11XQN23PROD with PROPOSALS2
TABLE LA–2—PROJECTED NONATTAINMENT AND MAINTENANCE RECEPTORS WITH LOUISIANA LINKAGES BASED ON EPA
2016V2 MODELING
2023
Average DV
(ppb)
Receptor
(site ID, county, state)
Nonattainment/
maintenance
482010024, Harris, TX ..................................
482010055, Harris, TX ..................................
480391004, Brazoria, TX ..............................
Nonattainment ..................................................
Nonattainment ..................................................
Maintenance .....................................................
65 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.
66 See August 2018 memorandum, at page 4.
67 Per the instructions in the Supplementary
Information section above, all public comments,
including comments on the EPA’s air quality
VerDate Sep<11>2014
20:06 Feb 18, 2022
Jkt 256001
modeling should be submitted in the Regional
docket for this action, Docket ID No. EPA–R06–
OAR–2021–0801. Comments are not being accepted
in Docket No. EPA–HQ–OAR–2021–0663.
68 DVs and contributions at individual monitoring
sites nationwide are provided in the file: ‘‘2016v2_
DVs_state_contributions.xlsx’’, which is included in
Docket ID No. EPA–HQ–OAR–2021–0663.
69 These modeling results are consistent with the
results of a prior round of 2023 modeling using the
2016v1 emissions platform, which became available
PO 00000
Frm 00017
Fmt 4701
Sfmt 4702
75.2
71.0
70.1
2023
Maximum DV
(ppb)
76.8
72.0
72.3
Louisiana
Contribution
(ppb)
4.31
5.39
7.03
to the public in the fall of 2020 in the Revised
CSAPR Update, as noted in Section I of this action.
That modeling showed that Louisiana had a
maximum contribution greater than 0.70 ppb to at
least one nonattainment or maintenance-only
receptor in 2023. These modeling results are
included in the file ‘‘Ozone DVs And Contributions
Revised CSAPR Update.xlsx’’ in Docket No. EPA–
HQ–OAR–2021–0663.
E:\FR\FM\22FEP2.SGM
22FEP2
9814
Federal Register / Vol. 87, No. 35 / Tuesday, February 22, 2022 / Proposed Rules
TABLE LA–2—PROJECTED NONATTAINMENT AND MAINTENANCE RECEPTORS WITH LOUISIANA LINKAGES BASED ON EPA
2016V2 MODELING—Continued
Nonattainment/
maintenance
481210034, Denton, TX ................................
482011034, Harris, TX ..................................
482011035, Harris, TX ..................................
Maintenance .....................................................
Maintenance .....................................................
Maintenance .....................................................
3. Evaluation of Information Provided
by LDEQ Regarding Step 3
lotter on DSK11XQN23PROD with PROPOSALS2
2023
Average DV
(ppb)
Receptor
(site ID, county, state)
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 contribute
significantly to nonattainment or
interfere with maintenance and, thus,
must be eliminated under CAA section
110(a)(2)(D)(i)(I).
To effectively evaluate 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 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
an analysis similar to the EPA’s (or an
alternative approach to defining
‘‘significance’’ that comports with CAA
requirements) to determine whether,
and to what degree, emissions from a
state should be ‘‘prohibited’’ to
eliminate emissions that will
‘‘contribute significantly to
nonattainment, or interfere with
maintenance of’’ the NAAQS in any
other state. LDEQ did not conduct such
VerDate Sep<11>2014
20:06 Feb 18, 2022
Jkt 256001
an analysis in their SIP submission.
Instead LDEQ interpreted the Act’s
requirements as only requiring an
analysis of emission reductions where
there was a ‘‘consistent and persistent’’
pattern of contribution and conducted
an air-quality-only analysis in order to
refute such a pattern. We propose to
find that LDEQ was required to analyze
emissions from the sources and other
emissions activity from within
Louisiana to determine whether its
contributions were significant, and we
propose to disapprove its submission
because LDEQ did not do so.
As noted, LDEQ stated in its SIP
submission that emissions from
Louisiana should not be considered to
contribute significantly to
nonattainment or interfere with
maintenance of the NAAQS in other
states because there is not a ‘‘persistent
and consistent’’ pattern of contribution
from the State. The SIP submission does
not explain what LDEQ considers to be
a persistent and consistent pattern of
contribution, even after the LDEQ
received a comment during its state
comment period that requested that the
LDEQ define ‘‘persistent and
consistent’’ in terms of impacts on
downwind states. The LDEQ responded,
‘‘Louisiana has defined the pattern and
has provided back trajectories on those
monitored exceedances for the 2016–
2018 ozone seasons, which will show
that the definition is applicable to the
conclusion.’’ 70 We do not agree that this
suffices as an explanation as to why
LDEQ does not need to further analyze
its potential emission reductions under
Step 3 before determining it has no
statutory obligation under the interstate
transport provision. In the case of
Louisiana, modeling in the March 2018
memorandum and the EPA’s more
recent 2016v2 modeling both project
that receptors in the Houston-GalvestonBrazoria (HGB) and Dallas-Fort Worth
(DFW) ozone nonattainment areas in
Texas will have difficulty attaining or
maintaining the 2015 ozone NAAQS,
and Louisiana’s contribution to these
70 See LDEQ SIP Submission, Appendix A,
available in the Regional docket for this action
(Docket ID No. EPA–R06–OAR–2021–0801).
PO 00000
Frm 00018
Fmt 4701
Sfmt 4702
70.4
70.3
68.0
2023
Maximum DV
(ppb)
72.2
71.6
71.6
Louisiana
Contribution
(ppb)
3.22
4.93
4.77
areas exceed both a 1 percent or a 1 ppb
threshold. While linkages to specific
receptors may change with updated
modeling, both modeling analyses
consistently show emissions from
Louisiana impact both downwind
nonattainment receptors and downwind
maintenance receptors in Texas.
The LDEQ SIP submission stated that
Louisiana’s contribution should be
deemed ‘‘significant’’ per CAA section
110(a)(2)(D)(i)(I) only if there is a
persistent and consistent pattern of
contribution on several days with
elevated ozone. LDEQ asserted that its
linkages to Texas do not warrant further
analysis because, according to LDEQ,
emissions from Louisiana do not
persistently and consistently contribute
on several days of elevated ozone.
However, the EPA modeling that LDEQ
relied upon to demonstrate linkages in
the first instance already establishes that
there is a consistent and persistent
pattern of contribution from Louisiana
to Texas receptors on elevated ozone
days. The EPA’s methodology for
projecting future year ozone
concentrations accounts for precisely
these concerns—the relative response
factor 71 that is applied to historic
monitored data to generate projections
is calculated by looking only at days
with elevated ozone levels. The EPA
notes that monitored attainment with
the ozone standard is determined by
averaging the fourth high value recorded
each year for three years. So, the EPA
believes it is important to estimate
impacts on the days with highest
projected ozone levels. The days chosen
to analyze the future impacts are chosen
initially by the selecting the 10 highest
days in the base period modeling that
are projected to be above 65 ppb in the
base period. If there are not 10 days
above 65 ppb at a potential receptor, the
number of days above 65 ppb are used
so long as there is at least five days
above 65 ppb in the base period. If the
air quality modeling shows fewer than
five days above 65 ppb in the base
period, then the data for impacts at that
receptor in 2023 are not calculated. The
base and future year modeling for these
71 See
E:\FR\FM\22FEP2.SGM
FN 53.
22FEP2
lotter on DSK11XQN23PROD with PROPOSALS2
Federal Register / Vol. 87, No. 35 / Tuesday, February 22, 2022 / Proposed Rules
5–10 days are then used to project 2023
ozone DVs to determine whether it is
projected to be a nonattainment or
maintenance receptor in 2023. For these
same 5–10 days identified, the future
year modeling provides the estimated
daily contribution at a potential
receptor’s future year daily MDA8 and
these daily contributions are averaged
for the 5–10 days to result in the average
contribution from the upwind area.
LDEQ’s air quality analysis used to
dismiss its linkages to Texas receptors
as not ‘‘significant’’ consists of an
evaluation of seasonal weather patterns,
surface wind directions, and periodic
back trajectories. The State’s weather
pattern analysis relied on large-scale
weather patterns as they relate to
commonly observed wind directions
rather than weather patterns and
conditions that are specifically
conducive to ozone formation or tied to
specific days when high ozone was
monitored in the downwind areas.
General weather pattern discussions
that are not associated with specific
ozone episodes are not generally
informative of interstate transport
decisions. It is necessary to investigate
specific instances of high ozone,
because as discussed previously,
violations of the ozone standard can be
driven by as few as 4 days per year
because the compliance with the
standard is evaluated based on the
average of the fourth high value
measured each of three consecutive
years.
LDEQ’s wind rose analysis is based on
surface sites in the Dallas-Fort Worth
areas, Houston-Galveston-Brazoria
areas, and other areas in Texas and
Louisiana, but the analysis does not
address transport winds between
Louisiana and the Texas areas with
receptors on high ozone days at the
identified receptors. There are several
limitations associated with LDEQ’s
wind rose analysis: (1) Wind directions
measured at the surface are not
necessarily good indicators of the wind
direction occurring at higher elevations,
which tend to have a stronger influence
on interstate ozone transport; (2) wind
directions change spatially over the
range of distance involved in transport
from Louisiana to Texas; (3) wind
directions change temporally over the
range of time involved in ozone
transport from Louisiana to Texas; and
(4) the wind roses are based on wind
data measured throughout the year, not
just during either ozone season or
monitored ozone episode days. In
addition, as discussed previously,
LDEQ’s wind rose analysis is not
limited to the wind conditions that are
conducive to high ozone, so it does not
VerDate Sep<11>2014
20:06 Feb 18, 2022
Jkt 256001
provide information directly pertinent
to when ozone is high at areas in Texas
and whether Louisiana is a contributing
area during those specific times.
LDEQ also included 99 back trajectory
analyses during the 2016, 2017, and
2018 years for the dates of ozone
exceedances at the monitors referenced
in Table LA–1 of this action. HYSPLIT
back trajectory analyses use archived
meteorological modeling that includes
actual observed data (surface, upper air,
airplane data, etc.) and modeled
meteorological fields to estimate the
most likely route of an air parcel
transported to a receptor at a specified
time. The method essentially follows a
parcel of air backward in hourly steps
for a specified length of time. HYSPLIT
estimates the central path in both the
vertical and horizontal planes. The
HYSPLIT central path represents the
centerline with the understanding that
there are areas on each side horizontally
and vertically that also contribute to the
concentrations at the end point. The
horizontal and vertical areas that
potentially contribute to concentrations
at the endpoint grow wider from the
centerline the further back in time the
trajectory goes. Therefore, a HYSPLIT
centerline does not have to pass directly
over emissions sources or emission
source areas but merely relatively near
emission source areas for those areas to
contribute to concentrations at the
trajectory endpoint. The EPA relies on
back trajectory analysis as a corollary
analysis along with observation-based
meteorological wind fields at multiple
heights to examine the general
plausibility of the photochemical model
‘‘linkages.’’ Since the back trajectory
calculations do not account for any air
pollution formation, dispersion,
transformation, or removal processes as
influenced by emissions, chemistry,
deposition, etc., the trajectories cannot
be used to develop quantitative
contributions. Therefore, back
trajectories cannot be used to
quantitatively evaluate the magnitude of
the existing photochemical
contributions from upwind states to
downwind receptors. LDEQ’s HYSPLIT
back trajectory analysis for 2016, 2017,
and 2018 showed that on high ozone
days in Texas at the receptors identified
by the EPA in the 2018 memorandum
that 28% of the trajectories passed
through Louisiana. LDEQ proffered that
some of these back trajectories did not
pass directly over areas with emissions
but did not consider that the back
trajectories only represent a centerline
and there are areas on either side of the
centerline that would be contributing
areas. LDEQ’s trajectory analysis
PO 00000
Frm 00019
Fmt 4701
Sfmt 4702
9815
confirmed that Louisiana is an upwind
area for the receptors in Texas often
enough to potentially contribute to
nonattainment or interfere with
maintenance. The analysis did not
provide evidence that was contrary to
the conclusions of the EPA’s
photochemical modeling analyses (i.e.,
the EPA’s modeling results in the March
2018 memorandum and EPA 2016v2
model).
Photochemical modeling simulations
for ozone interstate transport assessment
is relied upon by the EPA to simulate
the formation and fate of oxidant
precursors, primary and secondary
particulate matter concentrations, and
deposition over regional and urban
spatial scales. Photochemical modeling
is the most sophisticated tool available
to estimate future ozone levels and
contributions to those modeled future
ozone levels. Consideration of the
different processes that affect primary
and secondary pollutants at the regional
scale in different locations is
fundamental to understanding and
assessing the effects of emissions on air
quality concentrations. For the 2015
ozone NAAQS interstate transport
analysis, the EPA performed
nationwide, state-level ozone source
apportionment modeling using CAMx to
quantify the contribution of NOX and
VOC emissions from all sources in each
state to project 2023 ozone
concentrations at ozone monitoring
sites. Detailed information for the EPA’s
modeling may be found in the Air
Quality Modeling TSD in Docket No.
EPA–HQ–OAR–2021–0663.
LDEQ concluded in the SIP submittal,
citing an article 72 published in 2012,
that the use of 1 percent of the standard
for modeled contribution as the sole
definition of significant contribution is
inappropriate for the 2015 ozone
NAAQS. LDEQ’s reasoning for this
conclusion is that the more stringent 0.7
ppb threshold ‘‘is an order of magnitude
smaller than the biases and errors
typically documented for regional
photochemical modeling.’’ First, the
EPA does not use the 1 percent
threshold as the sole definition of
significant contribution; at Step 2 of the
analysis, the 1 percent threshold is used
to identify contributions between states
and downwind problem areas for
further analysis at Step 3. Second,
photochemical transport models such as
CAMx have been extensively peer
reviewed and used to support SIPs and
explore relationships between inputs
and air quality impacts in the U.S. and
beyond. The EPA works to continually
develop and update both the guidelines
72 Simon
E:\FR\FM\22FEP2.SGM
et al., supra FN 58.
22FEP2
9816
Federal Register / Vol. 87, No. 35 / Tuesday, February 22, 2022 / Proposed Rules
lotter on DSK11XQN23PROD with PROPOSALS2
on using modeling results and the latest
versions of photochemical model
platforms to support scientific
assessments and regulatory
determinations. Prior to using
photochemical modeling to support a
regulatory assessment, a model
performance evaluation is completed to
establish a benchmark to assess how
accurately the model predicts observed
concentrations and to identify model
limitations. The model performance
evaluation provides a better
understanding of the model’s
limitations and biases and serves as a
diagnostic evaluation for further model
development and improvement. As
discussed in Section I of this document
and the Air Quality Modeling TSD in
Docket No. EPA–HQ–OAR–2021–0663,
the EPA follows the most recent
established modeling guidance and
provides with this action the updated
modeling analysis based on the recent
CAMx model update. By using the most
recent 2016v2 photochemical modeling
enhancements (EPA 2016v2 modeling)
results are more representative of the
projected local and regional air quality
as it is based on more recent emission
estimates with fewer years between the
base case year (2016) and the future year
(2023). In addition, to reduce the impact
of any potential biases or errors, the
EPA uses the modeling results in a
relative sense rather than rely on
absolute model predictions.73
Furthermore, it is not appropriate to
compare the bias/error involved in the
estimation of total ozone to the potential
error in the estimation of the subset of
ozone that is contributed by a single
state. For example, on a specific day the
modeled vs. monitored ozone value may
differ by 2 ppb but that is relatively
small percentage of the total modeled
ozone, which for a receptor of interest
would be on the order of 70 ppb. It
would be unrealistic to assign all the 2
ppb, in the above example, to the
estimated impact from a single state as
the 2 ppb error would be the
combination of the error from all
sources of ozone that contribute to the
total, including estimated impacts from
other states, the home state of the
73 See ‘‘Modeling Guidance for Demonstrating Air
Quality Goals for Ozone, PM2.5 and Regional Haze’’,
Nov. 29, 2018, at 101, available at https://
www.epa.gov/sites/default/files/2020-10/
documents/o3-pm-rh-modeling_guidance-2018.pdf
(‘‘2018 Air Quality Modeling Guidance’’). See also
‘‘Draft Modeling Guidance for Demonstrating
Attainment of Air Quality Goals for Ozone, PM2.5,
and Regional Haze’’, Dec. 3, 2014, at 97–98,
available at https://www.epa.gov/sites/default/files/
2020-10/documents/draft-o3-pm-rh-modeling_
guidance-2014.pdf (‘‘2014 Draft Air Quality
Modeling Guidance’’).
VerDate Sep<11>2014
20:06 Feb 18, 2022
Jkt 256001
receptor and natural background
emissions.
In sum, the EPA disagrees that the
estimates of potential error in the
models estimates of total ozone, call
into question the use of 1 percent as a
threshold for linkage. As noted earlier,
in the case of Louisiana, the difference
between a 1 percent threshold and a 1
ppb threshold is irrelevant to the
decision here because linkages are
present at both threshold levels. As to
Louisiana’s conclusion that the impacts
from Louisiana’s emissions are not
persistent, the contribution analysis is
the average impact for at least 5 days
and up to 10 days for the 2016 base
period which is sufficiently persistent
considering the first through fourth high
monitored values set the monitored DV.
We recognize that the results of the
EPA (2011 and 2016 base year)
modeling indicated different receptors
and linkages at Steps 1 and 2 of the
4-Step interstate transport framework.
These differing results regarding
receptors and linkages can be affected
by the varying meteorology from year to
year, but we do not think the differing
results means that the modeling or the
EPA or the state’s methodology for
identifying receptors or linkages is
inherently unreliable. Rather, these
separate modeling runs all indicated: (1)
That there are receptors that would
struggle with nonattainment or
maintenance in the future; and (2) that
Louisiana is linked to some set of these
receptors, even if the receptors and
linkages differed from one another in
their specifics (e.g., Louisiana was
linked to a different set of receptors in
one modeling run versus another).
These results indicates that Louisiana’s
emissions were substantial enough to
generate linkages at Steps 1 and 2 to at
least some set of downwind receptors,
under varying assumptions and
meteorological conditions, even if the
precise set of linkages changed between
modeling runs.
4. Evaluation of Information Provided
by LDEQ 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, LDEQ’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
PO 00000
Frm 00020
Fmt 4701
Sfmt 4702
Step 4. To the extent that LDEQ
discussed emissions reductions, the
State only provided a summary of
existing already implemented
enforceable control regulations. The
EPA’s 2016v2 modeling analyses have
already accounted for the
implementation of the regulations cited
by LDEQ’s submission—including the
CSAPR rulemakings and prior regional
rulemakings—and even with those
reductions in place, the modeling
results consistently show receptors that
are projected to be in nonattainment or
to struggle with maintenance, and
Louisiana contributing to those
receptors. Relying only on the existing
enforceable control regulations is
insufficient to address the Louisiana air
emission contributions to linked
downwind air quality problems. As a
result, the EPA proposes to disapprove
LDEQ’s 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).
5. Conclusion
Based on the EPA’s evaluation of
LDEQ’s SIP submission, the EPA is
proposing to find that LDEQ’s
November 13, 2019, SIP submission
pertaining to interstate transport of air
pollution 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 ozone NAAQS
in any other state.
IV. Oklahoma SIP Submission
Addressing Interstate Transport of Air
Pollution for the 2015 Ozone NAAQS
and the EPA Evaluation of the SIP
Submission
A. Summary of ODEQ SIP Submission
Addressing Interstate Transport of Air
Pollution for the 2015 Ozone NAAQS
On October 25, 2018, the Oklahoma
Department of Environmental Quality
(ODEQ) made a SIP submission
addressing interstate transport of air
pollution for the 2015 ozone NAAQS.
The SIP submission provided ODEQ’s
analysis of their impact to downwind
states using the EPA’s 4-Step framework
and an analytic year of 2023 and
concluded that emissions from
Oklahoma will not contribute
significantly to nonattainment or
interfere with maintenance of the 2015
ozone NAAQS in other states.
To identify downwind air quality
problems that are linked to emissions
E:\FR\FM\22FEP2.SGM
22FEP2
Federal Register / Vol. 87, No. 35 / Tuesday, February 22, 2022 / Proposed Rules
from Oklahoma and therefore warrant
further review and analysis (Steps 1 and
2), ODEQ used EPA interstate transport
modeling results found in the March
2018 memorandum. The EPA modeling
results projected: (1) An average DV and
a maximum DV for the year 2023 for
ozone monitors in the 48 contiguous
States and (2) the expected contribution
from emissions in each state to the
ozone concentrations at each ozone
monitor.
ODEQ used the information from the
March 2018 EPA memorandum to
identify six downwind nonattainment
and maintenance receptors 74 with a
contribution from Oklahoma of 1
percent of the 2015 ozone NAAQS (0.70
parts ppb) or greater. ODEQ then
applied a 1 ppb threshold to remove
from further analysis three receptors
with a contribution from Oklahoma of
less than 1 ppb. ODEQ noted that the
possibility of using an alternative
contribution threshold was one of the
areas of flexibility identified in the
March 2018 EPA memorandum and
discussed further in the August 2018
9817
EPA memorandum. To support its
alternative contribution threshold,
ODEQ referenced an EPA memorandum
from April 17, 2018, which
recommended a Significant Impact
Level (SIL) for ozone of 1.0 ppb for
proposed sources subject to the
Prevention of Significant Deterioration
(PSD) permitting program.75 Table OK–
1 provides information on the six
nonattainment and maintenance
receptors identified by ODEQ, including
the three receptors ODEQ identified for
further analysis.
TABLE OK–1—NONATTAINMENT AND MAINTENANCE RECEPTORS IDENTIFIED BY ODEQ BASED ON THE EPA’S MARCH
2018 MEMORANDUM
2023
average DV
(ppb)
lotter on DSK11XQN23PROD with PROPOSALS2
Receptor
(site ID, county, state)
2023
maximum DV
(ppb)
Oklahoma
contribution
(ppb)
260050003, Allegan, MI ..................................
69.0
71.7
1.31
481210034, Denton, TX ..................................
69.7
72.0
1.23
484392003, Tarrant, TX ..................................
72.5
74.8
1.71
480391004, Brazoria, TX ................................
74.0
74.9
0.90
550790085, Milwaukee, WI ............................
71.2
73.0
0.76
551170006, Sheboygan, WI ...........................
72.8
75.1
0.95
ODEQ’s step 1 and 2 determination
Maintenance receptor identified for further
analysis.
Maintenance receptor identified for further
analysis.
Nonattainment receptor identified for further
analysis.
Nonattainment receptor with contribution less
than 1 ppb; no further analysis.
Nonattainment receptor with contribution less
than 1 ppb; no further analysis.
Nonattainment receptor with contribution less
than 1 ppb; no further analysis.
ODEQ further evaluated the two
Texas receptors (Tarrant County and
Denton County) and the receptor in
Allegan County, MI. ODEQ did not
further evaluate the contribution from
Oklahoma to the receptors in Brazoria
County, TX, Milwaukee County, WI,
and Sheboygan County, WI because the
contributions from Oklahoma to these
receptors were less than 1 ppb.
For the two remaining Texas
receptors, ODEQ returned to Steps 1 and
2 of the 4-Step interstate transport
framework using modeling performed
by the Texas Commission on
Environmental Quality (TCEQ). The
TCEQ modeling results are included in
the Regional docket for this action
(Docket ID No. EPA–R06–OAR–2021–
0801). ODEQ stated that the primary
difference between the EPA modeling
and the TCEQ modeling is that the
TCEQ modeling used 2012 as the ‘‘base
year’’ for assessing interstate transport
of ozone pollution in 2023 whereas the
EPA modeling used 2011 as the base
year for that assessment. In addition, the
ODEQ stated that TCEQ used a method
different from the EPA’s method to
identify whether a monitor would have
trouble maintaining the 2015 ozone
NAAQS (i.e., a maintenance receptor).
To identify maintenance receptors,
TCEQ calculated a ‘‘maintenance future
year (fy) DV’’ by projecting to 2023 the
most recent regulatory DV that contains
the base year (i.e., the 2012–2014 DV for
a base year of 2012), whereas the EPA’s
methodology for identifying
maintenance receptors uses the
maximum DV, which is the highest
monitored DV from among the three
DVs that contain the base year (i.e., the
2009–2011, 2010–2012 and 2011–2013
DVs for a base year of 2011).
To assess whether Oklahoma is linked
to nonattainment of the 2015 ozone
standard at the Denton and Tarrant
County sites, ODEQ switched to using
the 2023 average DV projected by TCEQ
rather than the EPA’s projected average
DVs. The ODEQ noted that the projected
2023 average DV was 68 ppb for the
Denton County site and 66 ppb for the
Tarrant County site based on the TCEQ
modeling. ODEQ then claimed that
these results demonstrate that both of
these sites are in attainment in 2023.
To assess whether Oklahoma
interferes with maintenance of the 2015
ozone standard at these two sites, ODEQ
used (1) the Texas method to calculate
a ‘‘maintenance future year DV’’ for
2023 and (2) a maximum DV calculated
using the highest of the three base year
DVs multiplied by a relative response
factor derived from TCEQ’s modeling
(i.e., EPA’s method for identifying
maintenance receptors but using TCEQ’s
modeling rather than EPA’s modeling).
This assessment is summarized in Table
OK–2.
74 Nonattainment receptors are monitoring sites
that are anticipated to have problems attaining and
maintaining the 2015 ozone NAAQS (i.e., average
projected 2023 DV greater than 70.9 ppb).
Maintenance receptors are monitoring sites that are
anticipated to have problems maintaining the 2015
ozone NAAQS (i.e., maximum projected 2023 DV
greater than 70.9 ppb).
75 See FN 32.
VerDate Sep<11>2014
20:06 Feb 18, 2022
Jkt 256001
PO 00000
Frm 00021
Fmt 4701
Sfmt 4702
E:\FR\FM\22FEP2.SGM
22FEP2
9818
Federal Register / Vol. 87, No. 35 / Tuesday, February 22, 2022 / Proposed Rules
TABLE OK–2—SUMMARY OF TCEQ MODELING (2012 BASE PERIOD) USED BY ODEQ TO ASSESS MAINTENANCE
RECEPTORS
2023
average DV
(ppb)
Receptor
(site ID, county, state)
2023
maximum DV
(ppb) (EPA
method)*
Maintenance
DV
(ppb)(TCEQ
method)
481210034 Denton, TX ...................................
68
70.7
65.9
484392003 Tarrant, TX ...................................
66
69.9
62.4
ODEQ’s step 1 and step 2 determination
Future DVs project no attainment or maintenance problems.
Future DVs project no attainment or maintenance problems.
lotter on DSK11XQN23PROD with PROPOSALS2
* These values are not based on calculations made by the EPA. ODEQ calculated these values by using the maximum DV for the 2010–2014
5-year period (i.e., the highest of the DVs in 2012, 2013, and 2014) multiplied by relative response factor for the receptor obtained from TCEQ’s
modeling.
ODEQ noted in their assessment that
based on the TCEQ modeling and TCEQ
definition of maintenance receptor, it is
expected that the Denton and Tarrant
sites will not experience nonattainment
or maintenance problems in 2023.
Because ODEQ claimed that the Denton
and Tarrant County sites will not be
nonattainment or maintenance receptors
in 2023, ODEQ did not analyze potential
emissions reductions at Step 3 to
address its contribution to these two
sites.
With respect to the remaining
receptor at Allegan County, MI, ODEQ
provided an analysis of projected 2023
DVs for this site and information on
emissions trends in Oklahoma to assert
that emissions from Oklahoma do not
significantly contribute to
nonattainment or interfere with
maintenance of the 2015 ozone NAAQS
at the Allegan County, MI site.
ODEQ noted that (1) the DV for the
Allegan County, MI site has had a
substantial reduction in the last 6 years
from 84 ppb in 2012 to 73 ppb in 2017,
a 1.8 ppb per year decrease, on average
and (2) the Allegan County, MI site is
substantially influenced by mobile
sources from the Chicago area and these
emissions are expected to be greatly
reduced in the near future, by roughly
a 1 ppb per year decrease, leading to
attainment of the 2015 ozone standard.
The ODEQ then calculated a projected
2023 maintenance DV for the Allegan
County, MI site using the EPA’s method,
but assuming that the base year was
2016 rather than 2011, as in the EPA’s
modeling or 2012 as in the TCEQ
modeling. The ODEQ noted that the
maximum DV in the 2016-centered base
period (i.e., 2014–2016, 2015–2017, and
2016–2018) was 75 ppb at the Allegan
County, Michigan site. The ODEQ then
calculated the difference between the
2011-centered base period maximum
DV of 86 ppb and the 2023 projected
maximum DV of 71.7 ppb, using data
from the EPA’s modeling. The ODEQ
calculated a ‘‘ppb per year’’ reduction of
1.1917 ppb per year, based on the 14.3
VerDate Sep<11>2014
20:06 Feb 18, 2022
Jkt 256001
ppb difference between the 2011centered and 2023 maximum DVs over
the 12 years from 2011 to 2023. Finally,
ODEQ applied the 1.1917 ppb per year
value to the 2016-centered maximum
DV of 75 ppb to estimate a 2023
maximum DV of 66.66 ppb.
ODEQ also asserted that the relatively
small contribution from Oklahoma (3%
of total upwind state contributions)
combined with the distance between
Oklahoma sources and the Allegan
County, Michigan site, warrants a focus
on nearby states with greater
proportional contributions as the most
prudent approach to addressing
interstate transport of ozone precursors
for this receptor.
The ODEQ also provided the
anthropogenic NOX and VOC data of
Oklahoma’s emissions from EPA’s
emission trends and modeling to
demonstrate an anticipated substantial
reduction of NOX and VOC from 2011
to 2023: (1) Reductions of NOX from
405,000 to 235,000 tons per year and (2)
reductions of VOC from 414,000 to
295,000 tons per year.76 ODEQ noted
these reductions should result in
considerable reductions in ozone
concentrations. The ODEQ stated that
due to the emissions reductions
required by rules like CSAPR, the 2016
CSAPR Update, and the regional haze
requirements, the NOX emissions from
electric generation in Oklahoma have
dropped significantly during the ozone
season from 38,285 tons per year in
2011 to 10,435 tons per year in 2017.
ODEQ also stated that changes in the
Southwest Power Pool 77, building of
76 ODEQ used the EPA’s emissions data shared
alongside the October 2018 memorandum, ‘‘statesector_annual_emissions_data_1.xlsx’’ available at
https://www.epa.gov/airmarkets/memo-andsupplemental-information-regarding-interstatetransport-sips-2015-ozone-naaqs.
77 The Southwest Power Pool is a regional electric
transmission organization regulated by the Federal
Energy Regulatory Commission whose purpose is
promoting efficiency and reliability in the operation
and planning of the electric transmission grid and
ensuring non-discrimination in the provision of
electric transmission services. It manages electric
PO 00000
Frm 00022
Fmt 4701
Sfmt 4702
additional windfarms, and electric
utilities installing solar generation
facilities have led to Oklahoma NOX
emissions reductions; and that any
additional NOX reductions from the
electric generation section would
require more costly emissions controls.
ODEQ concluded that the existing
controls in Oklahoma have resulted in
significant decreases in ozone DVs in
Oklahoma and that additional controls
would not be cost-effective. Given their
conclusions, ODEQ did not adopt
additional controls to reduce ozone
precursor emissions (Step 4).
B. EPA Evaluation of the ODEQ SIP
Submission
The EPA is proposing to find that
ODEQ’s October 25, 2018, SIP
submission does not demonstrate that
the State’s obligations with respect to
prohibiting emissions that contribute
significantly to nonattainment or
interfere with maintenance of the 2015
ozone NAAQS in any other state based
on the EPA’s evaluation of the SIP
submission using the 4-Step interstate
transport framework have been met. The
EPA is therefore proposing to
disapprove ODEQ’s submission.
1. Evaluation of Information Provided
by ODEQ Regarding Steps 1 and 2
As noted earlier, ODEQ first used the
information from the EPA’s March 2018
memorandum to identify nonattainment
and maintenance receptors with a
contribution from Oklahoma of 0.70 ppb
or greater (i.e., ODEQ identified
receptors that would be deemed
nonattainment and maintenance
receptors under the EPA’s methodology
for Steps 1 and 2). ODEQ then utilized
a 1 ppb threshold and elected not to
further analyze any receptors to which
it did not contribute greater than 1 ppb.
transmission in portions of fourteen states:
Arkansas, Iowa, Kansas, Louisiana, Minnesota,
Missouri, Montana, Nebraska, New Mexico, North
Dakota, Oklahoma, South Dakota, Texas and
Wyoming. See 18 CFR 35.34 and https://
www.ferc.gov/electric-power-markets.
E:\FR\FM\22FEP2.SGM
22FEP2
lotter on DSK11XQN23PROD with PROPOSALS2
Federal Register / Vol. 87, No. 35 / Tuesday, February 22, 2022 / Proposed Rules
ODEQ provided further evaluation of
the State’s emissions to those receptors
to which Oklahoma contributes greater
than 1 ppb (i.e., Allegan County, MI,
Denton County, TX and Tarrant County,
TX).
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, as an alternative to a 1
percent threshold, at Step 2 of the 4Step interstate transport framework, for
the purposes of identifying linkages to
downwind receptors. However, the
EPA’s August 2018 memorandum
provided that whether or not a 1 ppb
threshold is appropriate must be based
on an evaluation of state-specific
circumstances, and no such evaluation
was included in the ODEQ’s submittal.
Instead, ODEQ’s SIP submission
justified the State’s use of a 1 ppb
threshold based on the threshold’s use
in the SILs Guidance.78 ODEQ did not
explain the relevance of the SILs
Guidance to Oklahoma’s statutory
obligation under the interstate transport
provision. The SILs Guidance relates to
a different provision of the CAA
regarding implementation of the
prevention of significant deterioration
(PSD) permitting program, i.e., a
program that applies in areas that have
been designated attainment of the
NAAQS, and it is not applicable to the
interstate transport provision, which
requires states to eliminate emissions
that contribute significantly or interfere
with maintenance of the NAAQS at
known, ongoing, or projected air quality
problem areas in other states. The EPA
does not, in this action, agree that the
State has justified its application of the
1 ppb threshold.
Additionally, 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 threshold
at Step 2. (The memorandum also
indicated that any higher alternative
threshold, such as 2 ppb, would likely
not be appropriate.) However, the EPA
also provided that ‘‘air agencies should
consider whether the recommendations
in this guidance are appropriate for each
situation.’’ Following receipt and review
of 49 interstate transport SIP submittals
78 See
FN 32.
VerDate Sep<11>2014
20:06 Feb 18, 2022
Jkt 256001
for the 2015 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. 79 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.
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.80
The availability of different thresholds
at Step 2 has the potential to result in
inconsistent application of interstate
transport 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
79 ‘‘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 comments on this proposed approval and
has not taken final action with respect to this
proposal.
80 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.
PO 00000
Frm 00023
Fmt 4701
Sfmt 4702
9819
implementation of interstate transport
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 would 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 memorandum that there
was some similarity in the amount of
total upwind contribution captured (on
a nationwide basis) between 1 percent
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; 81 in
EPA 2016v2 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
81 See
E:\FR\FM\22FEP2.SGM
August 2018 memorandum, at page 4.
22FEP2
lotter on DSK11XQN23PROD with PROPOSALS2
9820
Federal Register / Vol. 87, No. 35 / Tuesday, February 22, 2022 / Proposed Rules
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 memorandum
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
basis for the EPA’s proposed
disapproval of ADEQ’s SIP submission
with respect to the Step 2 analysis is, in
the Agency’s view, warranted even
under the terms of the August 2018
memorandum. The EPA invites
comment on this broader discussion of
issues associated with alternative
thresholds at Step 2. (See
Supplementary Information section
above for details and docket to submit
comments). Depending on public
comments received in relation to this
action and further evaluation of this
issue, the EPA may determine to rescind
the 2018 memorandum in the future.
In any case, as discussed in the
following subsection, based on the
EPA’s most recent modeling, the State is
projected to contribute greater than both
the one percent and alternative 1 ppb
thresholds at the Denton County, TX
receptor, (Monitor ID. 481210034).
Based on the EPA’s modeling results
included in the March 2018
memorandum, Oklahoma was also
projected to contribute 1.23 ppb to the
Denton County, TX receptor. (In the
EPA 2016v2 modeling the Allegan
County, MI and Tarrant County, TX
receptors are not projected to have
problems attaining or maintaining the
2015 ozone NAAQS). Even under
ODEQ’s own analysis, the State was
linked to receptors with contributions
exceeding 1 ppb. Therefore, based on
Oklahoma’s 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 is
inconsequential to our proposed action
on the state’s SIP.
In the remainder of this section, EPA
evaluates ODEQ’s conclusions that
emissions from Oklahoma do not
contribute to nonattainment or interfere
with maintenance at receptors in
Tarrant County, TX (Monitor ID.
484392003) and Denton County, TX
(Monitor ID. 481210034). We evaluate
ODEQ’s conclusions as to the Allegan,
MI (Monitor ID. 260050003) in Section
IV.B.3 of this action.
VerDate Sep<11>2014
20:06 Feb 18, 2022
Jkt 256001
With regard to the Denton County and
Tarrant County, TX receptors cited in
ODEQ’s submission, ODEQ chose to rely
on the TCEQ’s modeling and
methodology, instead of the EPA
modeling, and trends in ozone DVs and
emissions to conclude that these
monitoring sites will be in attainment
by 2023 and will not have a problem
maintaining the 2015 ozone NAAQS. As
noted in Section IV.A of this action,
ODEQ used modeling results from the
TCEQ along with the TCEQ alternative
method for identifying maintenance
receptors to claim that using the TCEQ
modeling and methods, the Denton
County and Tarrant County monitors
would not have a problem maintaining
the NAAQS in 2023. The ODEQ
supplemented that analysis by citing the
downward trend in NOX and VOC
emissions in Oklahoma. ODEQ also
provided TCEQ modeling and emissions
data for the Dallas-Fort Worth
nonattainment area to show that mobile
sources represent the largest emissions
category in this area and that emissions
from this sector have declined since
2005 and are expected to continue to
decline in the future. As described in
Table OK–2, ODEQ (1) provided the
average 2023 DV for the Denton County,
TX receptor from the TCEQ modeling
and (2) used TCEQ modeling data with
a 2012 base year to calculate a 2023
maintenance DV of 65.9 ppb (using the
TCEQ methodology for identifying
maintenance receptors) and a 2023
maximum DV of 70.7 ppb (using the
EPA methodology for identifying
maintenance receptors, combined with
TCEQ’s modeling results). ODEQ relied
on this information, which is based on
TCEQ modeling with a 2012 base year,
to conclude that the Denton County, TX
and Tarrant County, TX monitors would
not have problems attaining and
maintaining the 2015 ozone NAAQS.
ODEQ’s SIP submission (or TCEQ, to
the extent that Oklahoma is merely
incorporating and relying on Texas’
submission) does not adequately
explain or justify how relying on
TCEQ’s method for identifying
maintenance receptors reasonably
identifies areas that will have difficulty
maintaining the NAAQS. EPA proposes
to find that ODEQ has provided no
sound technical basis (either on its own
or through reliance on Texas) for how
its chosen methodology gives meaning
to the CAA’s instruction that states
submit interstate transport SIPs that
prohibit their states’ emissions from
interfering with the maintenance of the
NAAQS in another state.
In North Carolina v. EPA, 531 F.3d
896, 909–11 (D.C. Cir. 2008), the D.C.
Circuit rejected the EPA’s CAIR on the
PO 00000
Frm 00024
Fmt 4701
Sfmt 4702
basis that the EPA had not adequately
given meaning to the phrase ‘‘interfere
with maintenance’’ in the interstate
transport provision. Specifically, North
Carolina argued that it had counties that
were projected to attain the NAAQS in
the future analytic year, but were at risk
of falling back into nonattainment due
to interference from upwind sources,
particularly given year-to-year
variability in ozone levels. The court
agreed, holding that the EPA’s rule did
not adequately protect ‘‘[a]reas that find
themselves barely meeting attainment.’’
Id. at 910. Consequently, the EPA has
developed a methodology, used in its
2011 CSAPR and its 2016 CSAPR
Update and Revised CSAPR Update, for
identifying areas that may struggle to
maintain the NAAQS. See 76 FR at
48227–28. EPA’s approach to addressing
maintenance receptors was upheld in
the EME Homer City litigation. See 795
F.3d 118, 136–37. It was also upheld in
Wisconsin. 938 F.3d at 325–26. In
Wisconsin, the court noted that four
upwind states were linked only to
maintenance receptors and rejected the
argument that application of the same
control level as EPA imposes for those
states linked to nonattainment receptors
was unreasonable or unlawful absent a
particularized showing of overcontrol.
Id. at 327.
In order to explain the differences
between TCEQ’s and the EPA’s
methodology for identifying
maintenance receptors, it is helpful to
provide some additional context of how
the EPA projects future air quality.
The EPA’s air quality modeling
guidance has long recommended
developing a base DV (i.e., the DV that
will be used as a starting point to model
and analyze for purposes of projecting
future air quality concentrations) that is
the average of three DVs spanning a
five-year period, centered around one
year for which an emissions inventory
will be submitted (e.g., if 2011 was the
base emissions inventory year, a state
would use monitored values from 2009–
2011, 2010–2012, 2011–2013 as the
starting point for projecting air quality
concentrations in future years).82 The
average of these three DVs is then
multiplied by a relative response
factor 83 to generate an average DV for
the future year.84 If a receptor’s average
82 See
FN 73.
FN 53.
84 While it is not critical to this discussion, for
purposes of explanation, the relative response factor
is a fractional change that represents how ozone at
a given receptor responds to changes in emissions
when all other variables are constant. For more
explanation of the RRF, please see 2018 Air Quality
Modeling Guidance or 2014 Draft Air Quality
Modeling Guidance.
83 See
E:\FR\FM\22FEP2.SGM
22FEP2
lotter on DSK11XQN23PROD with PROPOSALS2
Federal Register / Vol. 87, No. 35 / Tuesday, February 22, 2022 / Proposed Rules
future year DV is greater than or equal
to the level of the NAAQS, and the
receptor has recent monitored data that
violates the NAAQS, that receptor is
considered a ‘‘nonattainment’’ receptor
at Step 1. To identify maintenance
receptors, the EPA’s methodology looks
to the highest DV of the three DVs used
to calculate the 5-year weighted average
DV (e.g., in the 2011 example, if 2009–
2011 had the highest DV of 2009–2011,
2010–2012, and 2011–2013). The EPA
then applies the same relative response
factor to that highest DV to generate a
projected future maximum DV. Where a
receptor’s maximum DV exceeds the
level of the NAAQS, the EPA has
deemed those receptors to be
‘‘maintenance’’ receptors. This
methodology was designed to address
the D.C. Circuit’s holding that the CAA’s
‘‘interference with maintenance’’ prong
requires states and the EPA to protect
areas that may struggle with
maintaining the standard in the face of
variable conditions.
In its modeling, TCEQ adopted an
identical approach to the EPA’s for
identifying nonattainment receptors—it
looked at three sets of DVs over a fiveyear period and averaged those DVs to
generate a base year DV. TCEQ then
applied a relative response factor to that
base year DV to project a receptor’s
average DV in the future year. For
maintenance receptors, however, TCEQ
elected not to examine variability in
DVs over a five-year period by using the
highest DV of the three DVs making up
the base year DV. Instead, TCEQ (and by
extension, ODEQ), used only the most
recent DV of the three DVs, regardless
of whether the most recent DV was
highest or lowest. TCEQ’s proffered
explanation for using the most recent
DV to identify maintenance receptors
was that the latest DV ‘‘takes into
consideration . . . any emissions
reductions that might have occurred.’’ 85
TCEQ in its submission does not
explain why or how this methodology
identifies those areas that may be
meeting the NAAQS or that may be
projected to meet the NAAQS but may
nevertheless struggle to maintain the
NAAQS, given meteorological
variability. In fact, because TCEQ’s
stated purpose in using the most recent
DV was to capture more recent
emissions reductions, Texas’
methodology appears to be aimed at
limiting receptors which could be
identified as maintenance receptors,
compared to the EPA’s methodology,
which was designed to identify those
85 TCEQ submission at 3–39 to 3–40, available in
the Regional docket for this action (Docket ID No.
EPA–R06–OAR–2021–0801).
VerDate Sep<11>2014
20:06 Feb 18, 2022
Jkt 256001
areas that might struggle to maintain the
NAAQS in particularly ozone conducive
conditions.
As discussed further in the EPA
Region 6 TSD 86 for this action, the EPA
has reviewed the set of 21 receptors for
which Texas had contributions of 0.7
ppb or more in the EPA’s 2016 base year
modeling analyses, or TCEQ’s modeling
(2012 base year), and evaluated the
results of using TCEQ’s alternate
maintenance methodology. For these 21
receptors, TCEQ’s method resulted in 15
of the 21 2023 maintenance DVs
predicted to be lower than the 2023
nonattainment DVs from the
nonattainment methodology that uses
the 5-year center weighted average. Of
these 15 receptors, three receptors have
2023 maintenance DVs that are 3 ppb
lower, five receptors have 2023
maintenance DVs that are 2 ppb lower,
and seven receptors have 2023
maintenance DVs that are 1 ppb lower.
In comparison, using the EPA’s
maintenance methodology results in all
21 2023 maintenance DVs being equal
or up to 4 ppb higher than the 2023
nonattainment DVs. Again, the EPA
uses the average of the three DVs that
contain the base year modeled for the
nonattainment methodology and the
maximum of these three DVs for the
maintenance methodology. Because
TCEQ’s maintenance methodology of
just using the most recent DV (2012–
2014 DV) often results in maintenance
DVs lower than the 2023 nonattainment
DVs methodology results, the EPA finds
that the TCEQ methodology is not
adequately identifying conditions when
a receptor would have more difficulty
maintaining the standard. In fact, the
TCEQ’s method also identified one
receptor in their SIP submission as a
nonattainment receptor in 2023 that
would not have been identified as a
maintenance receptor, which further
highlights the concern that TCEQ’s
method did not adequately identify
areas that may struggle to maintain the
standard. TCEQ did not address
whether the three years that comprise
the most recent design value (i.e., 2012,
2013, and 2014) had meteorological
conditions highly conducive for
formation of high ozone concentrations
and thus would be an appropriate time
period to assess whether area could
have difficulty maintaining the standard
and the EPA’s analysis confirms that
this time period is not highly conducive
to ozone formation, at least for many
86 ‘‘EPA Region 6 2015 8-Hour Ozone Transport
SIP Proposal Technical Support Document’’ (EPA
Region 6 2015 Ozone Transport SIP TSD.pdf)
included in Docket ID No. EPA–R06–OAR–2021–
0801.
PO 00000
Frm 00025
Fmt 4701
Sfmt 4702
9821
receptors. The consequence of TCEQ’s
maintenance method is that it often
results in lower DVs than the
nonattainment method as demonstrated
by our analysis, which indicates that it
is often not considering conditions
when an area would have difficulty
maintaining the standard. Further, it is
unreasonable to have a method that
would not identify nonattainment
receptors also as maintenance receptors.
Again, EPA also assessed a number of
monitored DV trends that were provided
in TCEQ’s SIP and previous TCEQ
attainment demonstration SIPs
indicating that there are at times large
annual fluctuations upward from year to
year in monitored DVs (sometimes 2–3
ppb increase in one year) that are due
to variations in meteorology. Neither
TCEQ nor ODEQ addressed in their SIP
submissions whether the three years
that comprise the most recent DV (i.e.,
2012, 2013, and 2014) had
meteorological conditions conducive for
formation of high ozone concentrations.
On the other hand, the EPA
methodology can identify variations in
ozone levels that might result in
difficulty in maintaining the standard
over a longer period of time. The TCEQ
method will only identify areas that
have difficulty maintaining the standard
for a single design value period and, as
a result, does not address the
meteorological variability issue
sufficiently.
In its SIP submittal, ODEQ contended
that, based on TCEQ’s use of a 2012 base
year, and using TCEQ’s air quality
modeling, even if Texas had used the
EPA’s method of identifying
maintenance receptors, the projected
maximum DV for the Denton County
and Tarrant County receptors would be
70.7 ppb and 69.9 ppb, respectively,
which are considered to be in
attainment of the 2015 ozone NAAQS in
2023. However, this conclusion relied
upon a relative response factor derived
from the TCEQ modeling and TCEQ’s
modeling results, which are discussed
in more detail in Section V of this action
and in the EPA Region 6 TSD.87 TCEQ’s
modeled projections for 2023 including
nonattainment and maintenance values
(using either TCEQ’ or EPA’s
methodology) are much lower than
recent monitored values (2018–2020 DV
and preliminary 2019–2021 DVs) 88 for
87 Id.
88 Monitoring data from the EPA’s Air Quality
System (AQS) (https://www.epa.gov/aqs). 2021
monitoring data is preliminary and still has to
undergo Quality Assurance/Quality Control
analysis and be certified by the State of Texas,
submitted to EPA, and reviewed and concurred on
by EPA. 2018–2020 DVs are 72 ppb and 73 ppb at
E:\FR\FM\22FEP2.SGM
Continued
22FEP2
9822
Federal Register / Vol. 87, No. 35 / Tuesday, February 22, 2022 / Proposed Rules
many monitors and the amount of
further DV reductions needed to match
TCEQ’s modeling is more than is
reasonably expected to occur for many
monitors/receptors. This
underestimation of future DVs results in
mis-identifying these two receptors and
other receptors as not being
nonattainment or maintenance
receptors. Specifically, these two
receptors would need to have at least a
3–4 ppb decrease in the next 2–3 years
just to attain the 2015 Ozone NAAQS in
2023. As discussed in the EPA Region
6 TSD, TCEQ’s previous DFW
Attainment Demonstration SIP includes
long-term DV trends analysis that
indicates that DFW DVs decrease
approximately 1 ppb per year.89
Moreover, as discussed in Section
IV.B.2 of this action, the EPA’s updated
modeling, which relies upon more
recent data and the latest information on
emissions reductions, indicates that the
maximum design value in 2023 for the
Denton County receptor is 72.2 ppb.
Recent monitored air quality data at the
Denton receptor are consistent with the
EPA’s projections that this is an area
that will struggle to maintain the 2015
ozone NAAQS in 2023; the 2020 DV for
Denton was 72 ppb.90
Finally, in its submittal, ODEQ
pointed to the significant reductions in
emissions that have occurred in the
State, but the EPA believes these
reductions have already been accounted
for in the most recent modeling;
therefore, even with these reductions,
the Denton County, TX receptor is
projected to struggle with maintenance
of the 2015 ozone NAAQS in 2023.
2. Results of the EPA’s Step 1 and Step
2 Modeling and Findings for Oklahoma
As described in Section I of this
action, the EPA performed air quality
modeling using the 2016v2 platform to
project DVs and contributions for 2023.
This data was examined to determine if
Oklahoma contributes at or above the
threshold of 1 percent of the 2015 ozone
NAAQS (0.70 ppb) to any downwind
nonattainment or maintenance receptor.
As shown in Table OK–3, the most
recent modeling data 91 indicate that in
2023, emissions from Oklahoma
contribute greater than one percent of
the standard to maintenance-only
receptors in Denton County, TX and in
Cook County, IL. Oklahoma is not
linked to any nonattainment receptors
in EPA’s most recent modeling (EPA
2016v2 modeling). Therefore, based on
the EPA’s evaluation of the information
submitted by ODEQ and based on the
EPA’s most recent modeling results for
2023, the EPA proposes to find that
Oklahoma is linked at Steps 1 and 2 and
has an obligation to assess potential
emissions reductions from sources or
other emissions activity at Step 3 of the
4-Step framework.
TABLE OK–3—PROJECTED NONATTAINMENT AND MAINTENANCE RECEPTORS WITH OKLAHOMA LINKAGES IN 2023 BASED
ON EPA 2016V2 MODELING
Receptor
(site ID, county, state)
Nonattainment/maintenance
481210034, Denton, TX ...............................
170310032, Cook, IL ....................................
Maintenance .........................
Maintenance .........................
lotter on DSK11XQN23PROD with PROPOSALS2
3. Evaluation of Information Provided
by ODEQ 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 contribute
significantly to nonattainment or
interfere with maintenance and, thus,
must be eliminated under CAA section
110(a)(2)(D)(i)(I).
To effectively evaluate 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
the Denton County and Tarrant County monitors/
receptors respectively. Preliminary 2019–2021 DVs
are 74 ppb and 72 ppb at the Denton County and
Tarrant County monitors/receptors respectively.
89 EPA also analyzed trends using AQS data, See
EPA Region 6 TSD.
VerDate Sep<11>2014
20:06 Feb 18, 2022
Jkt 256001
2023
average DV
(ppb)
2020 DV
72
74
70.4
69.8
2023
maximum DV
(ppb)
72.2
72.4
Oklahoma
contribution
(ppb)
1.19
0.75
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. at 519. 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. ODEQ did not conduct such
an analysis in their SIP submission.
As noted earlier, ODEQ provided
some data on emissions and already
implemented emissions reductions for
sources in Oklahoma and stated that the
2016 CSAPR Update is the only
reasonable control warranted based on
Oklahoma’s limited contributions to the
Michigan and Texas receptors. Thus,
Oklahoma relied on its EGUs being
subject to the CSAPR Update (which
reflected a stringency at the nominal
marginal cost threshold of $1400/ton
(2011$) for the 2008 ozone NAAQS) to
argue that it had already implemented
all cost-effective emissions reductions,
and had no additional statutory
90 DVs 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.
91 These modeling results are consistent with the
results of a prior round of 2023 modeling using the
2016v1 emissions platform which became available
to the public in the fall of 2020 in the Revised
CSAPR Update, as noted above. That modeling
showed that Oklahoma had a maximum
contribution greater than 0.70 ppb to at least one
nonattainment or maintenance-only receptor in
2023. These modeling results are included in
‘‘Ozone DVs And Contributions Revised CSAPR
Update.xlsx’’ in Docket ID No. EPA–HQ–OAR–
2021–0663.
PO 00000
Frm 00026
Fmt 4701
Sfmt 4702
E:\FR\FM\22FEP2.SGM
22FEP2
lotter on DSK11XQN23PROD with PROPOSALS2
Federal Register / Vol. 87, No. 35 / Tuesday, February 22, 2022 / Proposed Rules
obligation to prohibit emissions under
CAA section 110(a)(2)(D)(i)(I) with
respect to the 2015 ozone NAAQS.
The EPA disagrees with ODEQ’s
conclusions for the following reasons:
First, the CSAPR Update did not
regulate non-electric generating units,
and thus this analysis is incomplete. See
Wisconsin, 938 F.3d at 318–20. Second,
relying on the CSAPR Update’s (or any
other CAA program’s) determination of
cost-effectiveness without further Step 3
analysis is not approvable. Costeffectiveness must be assessed in the
context of the specific CAA program;
assessing cost-effectiveness in the
context of ozone transport should reflect
a more comprehensive evaluation of the
nature of the interstate transport
problem, the total emissions reductions
available at several cost thresholds, and
the air quality impacts of the reductions
at downwind receptors. While the EPA
has not established a benchmark costeffectiveness value for 2015 ozone
NAAQS interstate transport obligations,
because the 2015 ozone NAAQS is a
more stringent and more protective air
quality standard, it is reasonable to
expect control measures or strategies to
address interstate transport under this
NAAQS to reflect higher marginal
control costs. As such, the marginal cost
threshold of $1,400/ton for the CSAPR
Update (which addresses the 2008
ozone NAAQS and is in 2011$) is not
an appropriate cost threshold and
cannot be approved as a benchmark to
use for interstate transport SIP
submissions for the 2015 ozone
NAAQS.
In addition, the most recent EPA
modeling captures all existing CSAPR
trading programs in the baseline, and
that modeling confirms that these
control programs were not sufficient to
eliminate Oklahoma’s linkage at Steps 1
and 2 under the 2015 ozone NAAQS.
The State was therefore obligated at
Step 3 to assess additional control
measures using a multifactor analysis.
Finally, relying on a FIP at Step 3 is
per se not approvable if the state has not
adopted that program into its SIP and
instead continues to rely on the FIP.
States may not rely on FIP measures to
meet SIP requirements. See CAA section
110(a)(2)(D) (‘‘Each such [SIP] shall . . .
contain adequate provisions . . . .’’).
See also CAA section 110(a)(2)(A);
Committee for a Better Arvin v. U.S.
E.P.A., 786 F.3d 1169, 1175–76 (9th Cir.
2015) (holding that measures relied on
by state to meet CAA requirements must
be included in the SIP).
In addition, ODEQ’s submission
included a weight of evidence
evaluation of its contribution to the
Allegan County, MI receptor to
VerDate Sep<11>2014
20:06 Feb 18, 2022
Jkt 256001
conclude that it does not contribute
significantly to nonattainment or
maintenance at the receptor.
The EPA disagrees with respect to
ODEQ’s assertion regarding the
relatively small contribution of
emissions from Oklahoma to the
Allegan County, MI receptor compared
to emissions from other upwind states
such as Illinois. Whether emissions
from other states or countries also
contribute to the same downwind air
quality issue is irrelevant in assessing
whether a downwind state has an air
quality problem, or whether an upwind
state is contributing significantly to that
problem. States are not obligated under
CAA section 110(a)(2)(D)(i)(I) to reduce
emissions sufficient on their own to
resolve downwind receptors’
nonattainment or maintenance
problems. Rather, states are obligated to
eliminate their own significant
contribution or interference with the
ability of other states to attain or
maintain the NAAQS.
Further, the court in Wisconsin
explained that downwind jurisdictions
often may need to heavily rely on
emissions reductions from upwind
states in order to achieve attainment of
the NAAQS, 938 F.3d at 316–17; such
states would face increased regulatory
burdens including the risk of bumping
up to a higher nonattainment
classification if attainment is not
reached by the relevant deadline,
Maryland, 958 F.3d at 1204. Indeed, the
D.C. Circuit in Wisconsin specifically
rejected petitioner arguments suggesting
that upwind states should be excused
from interstate transport obligations on
the basis that some other sources of
emissions (whether international or
another upwind state) could be
considered the ‘‘but-for’’ cause of
downwind air quality problem. 938
F.3dat 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 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.
PO 00000
Frm 00027
Fmt 4701
Sfmt 4702
9823
Comm’n on Envtl. Quality v. EPA,790
F.3d 138, 163 n. 12 (D.C. Cir. 2015)
(observing that the argument the ‘‘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 upwind states also contribute
some amount of pollution to the same
receptors to which the state is linked.
As explained in Section IV.A of this
action, ODEQ’s weight of evidence also
concluded that the Allegan receptor
would be attaining the NAAQS in 2023
based on an analysis that assumed a
projection of a linear reduction in DVs
across a 12-year period (2011 to
projected 2023 values), and then
applied that annual reduction (1.1917
ppb/year) to the receptor’s 2016centered base period maximum DV (75
ppb). The EPA does not necessarily
agree that the assumptions made in
Oklahoma’s weight-of-evidence analysis
are reasonable; however, because the
updated modeling also shows that
Allegan County, MI is no longer a
receptor in 2023, we propose to find
such assumptions are inconsequential to
our action on Oklahoma’s SIP.
We recognize that the results of the
EPA (2011 and 2016 base year)
modeling indicated different receptors
and linkages at Steps 1 and 2 of the 4Step interstate transport framework.
These differing results regarding
receptors and linkages can be affected
by the varying meteorology from year to
year, but we do not think the differing
results mean that the modeling or the
EPA methodology for identifying
receptors or linkages is inherently
unreliable. Rather, these separate
modeling runs all indicated: (1) That
there are receptors that would struggle
with nonattainment or maintenance in
the future; and (2) that Oklahoma was
linked to some set of these receptors,
even if the receptors and linkages
differed from one another in their
specifics (e.g., Oklahoma was linked to
a different set of receptors in one
modeling run versus another). These
results indicate that emissions from
Oklahoma are substantial enough to
generate linkages at Steps 1 and 2 to at
least some downwind receptors, under
varying assumptions and meteorological
conditions, even if the precise set of
linkages changed between modeling
runs.
We therefore propose that ODEQ was
required to analyze emissions from the
sources and other emissions activity
from within the State to determine
E:\FR\FM\22FEP2.SGM
22FEP2
9824
Federal Register / Vol. 87, No. 35 / Tuesday, February 22, 2022 / Proposed Rules
whether its contributions were
significant. Because ODEQ failed to
perform this analysis, we propose to
disapprove its submission.
4. Evaluation of Information Provided
by ODEQ 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, ODEQ’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, EPA proposes to
disapprove ODEQ’s 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).
5. Conclusion
Based on the EPA’s evaluation of
ODEQ’s SIP submission, the EPA is
proposing to find that the portion of
ODEQ’s 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 which will interfere with
maintenance of the 2015 ozone NAAQS
in any other state.
lotter on DSK11XQN23PROD with PROPOSALS2
C. Impact on Areas of Indian Country
Following the U.S. Supreme Court
decision in McGirt v Oklahoma, 140 S
Ct. 2452 (2020), the Governor of the
State of Oklahoma requested approval
under Section 10211(a) of the Safe,
Accountable, Flexible, Efficient
Transportation Equity Act of 2005: A
Legacy for Users, Public Law 109–59,
119 Stat. 1144, 1937 (August 10, 2005)
(‘‘SAFETEA’’), to administer in certain
areas of Indian country (as defined at 18
U.S.C. 1151) the State’s environmental
regulatory programs that were
previously approved by the EPA for
areas outside of Indian country. The
State’s request excluded certain areas of
Indian country further described below.
In addition, the State only sought
approval to the extent that such
approval is necessary for the State to
administer a program in light of
Oklahoma Dept. of Environmental
VerDate Sep<11>2014
20:06 Feb 18, 2022
Jkt 256001
Quality v. EPA, 740 F.3d 185 (D.C. Cir.
2014).92
On October 1, 2020, the EPA
approved Oklahoma’s SAFETEA request
to administer all of the State’s EPAapproved environmental regulatory
programs, including the Oklahoma SIP,
in the requested areas of Indian country.
As requested by Oklahoma, the EPA’s
approval under SAFETEA does not
include Indian country lands, including
rights-of-way running through the same,
that: (1) Qualify as Indian allotments,
the Indian titles to which have not been
extinguished, under 18 U.S.C. 1151(c);
(2) are held in trust by the United States
on behalf of an individual Indian or
Tribe; or (3) are owned in fee by a Tribe,
if the Tribe (a) acquired that fee title to
such land, or an area that included such
land, in accordance with a treaty with
the United States to which such Tribe
was a party, and (b) never allotted the
land to a member or citizen of the Tribe.
The EPA’s approval under SAFETEA
expressly provided that to the extent the
EPA’s prior approvals of Oklahoma’s
environmental programs excluded
Indian country, any such exclusions are
superseded for the geographic areas of
Indian country covered by the EPA’s
approval of Oklahoma’s SAFETEA
request.93 The approval also provided
that future revisions or amendments to
Oklahoma’s approved environmental
regulatory programs would extend to
the covered areas of Indian country
(without any further need for additional
requests under SAFETEA).94
92 In ODEQ v. EPA, the D.C. Circuit held that
under the CAA, a state has the authority to
implement a SIP in non-reservation areas of Indian
country in the state, where there has been no
demonstration of tribal jurisdiction. Under the D.C.
Circuit’s decision, the CAA does not provide
authority to states to implement SIPs in Indian
reservations. ODEQ did not, however, substantively
address any request under the separate authority in
Indian country provided specifically to Oklahoma
under SAFETEA. That separate authority was not
invoked until the State submitted its request under
SAFETEA, and was not approved until the EPA’s
decision, described in this section, on October 1,
2020.
93 The EPA’s prior approvals relating to
Oklahoma’s SIP frequently noted that the SIP was
not approved to apply in areas of Indian country
(consistent with the D.C. Circuit’s decision in
ODEQ v. EPA) located in the state. See, e.g., 85 FR
20178, 20180 (April 10, 2020). Such prior expressed
limitations are superseded by the EPA’s approval of
Oklahoma’s SAFETEA request.
94 On December 22, 2021, the EPA proposed to
withdraw and reconsider the October 1, 2020
SAFETEA approval. See https://www.epa.gov/ok/
proposed-withdrawal-and-reconsideration-andsupporting-information. The EPA is engaging in
further consultation with tribal governments and
expects to have discussions with the State of
Oklahoma as part of this reconsideration. The EPA
also notes that the October 1, 2020 approval is the
subject of a pending challenge in Federal court.
Pawnee Nation of Oklahoma v Regan, No. 20–9635
(10th Cir.). The EPA may make further changes to
PO 00000
Frm 00028
Fmt 4701
Sfmt 4702
As explained earlier, the EPA is
proposing to find that the portion of
Oklahoma’s 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 which will contribute
significantly to nonattainment or
interfere with maintenance of the 2015
ozone NAAQS in any other state.
Consistent with the D.C. Circuit’s
decision in ODEQ v. EPA and the EPA’s
October 1, 2020, SAFETEA approval,
this disapproval if finalized as proposed
will extend to areas of Indian country in
Oklahoma where the State has SIP
planning authority.
V. Texas SIP Submission Addressing
Interstate Transport of Air Pollution for
the 2015 Ozone NAAQS and the EPA
Evaluation of the SIP Submission
A. Summary of TCEQ SIP Submission
Addressing Interstate Transport of Air
Pollution for the 2015 Ozone NAAQS
On August 17, 2018, the Texas
Commission on Environmental Quality
(TCEQ) made a SIP submission
addressing interstate transport of air
pollution for the 2015 ozone NAAQS.
The SIP submission provided TCEQ’s
analysis of their impact to downwind
states using a framework similar to
EPA’s 4-Step framework and concluded
that emissions from Texas will not
contribute significantly to
nonattainment or interfere with
maintenance of the 2015 ozone NAAQS
in other states.
In the submittal, TCEQ provided the
steps they used to assess whether
emissions from Texas contribute
significantly to nonattainment or
interfere with maintenance of the 2015
ozone NAAQS in other States: (1)
Identify monitors projected to be in
nonattainment or have maintenance
issues in future year 2023; (2) identify
for further review projected
nonattainment and/or maintenance
monitors in other states that are
impacted by emissions from Texas; and
(3) determine if emissions from Texas
contribute significantly to
nonattainment or interfere with
maintenance at the monitors identified
in TCEQ Step 2. TCEQ stated that their
Step 1 is the same as EPA’s Step 1 and
that their Steps 2 and 3 are equivalent
to EPA’s Step 2. TCEQ used a
the approval of Oklahoma’s program to reflect the
outcome of the proposed withdrawal and
reconsideration of the October 1, 2020 SAFETEA
approval. To the extent any change occurs in the
scope of Oklahoma’s SIP authority in Indian
country before the finalization of this proposed
rule, such a change may affect the scope of the
EPA’s final action on the proposed rule.
E:\FR\FM\22FEP2.SGM
22FEP2
Federal Register / Vol. 87, No. 35 / Tuesday, February 22, 2022 / Proposed Rules
contribution threshold of one percent of
the NAAQS (0.7 ppb) in their Step 2
analysis to identify nonattainmentand/
or maintenance monitors in other states
that are impacted by emissions from
Texas. TCEQ further stated that EPA’s
Steps 3 and 4 are relevant only if
emissions from Texas contribute
significantly to nonattainment or
interfere with maintenance at
downwind monitors in another state.
Because Texas TCEQ concluded that it
has no such emissions, EPA’s Steps 3
and 4 are not addressed in the SIP
submission.
To identify monitors projected to be
in nonattainment or have maintenance
issues in 2023, (EPA Step 1 and TCEQ
Step 1), TCEQ conducted its own
regional photochemical modeling using
a 2012 base year. TCEQ’s modeling and
EPA’s modeling differ in significant
respects, which are discussed in detail
in the EPA Region 6 2015 8-Hour Ozone
Transport SIP Proposal Technical
Support Document (EPA Region 6
TSD).95 In particular, TCEQ used a 2012
base year, stating that (1) the year 2012
had above average temperatures across
most of the U.S., except in some states
in the southeast and (2) the year 2011,
(which was used by the EPA in the
NODA published on January 6, 2017
and the October 2017 updated modeling
data for 2023),96 was a meteorologically
anomalous year for Texas and
surrounding states as it was the hottest
year on record and the single-worst
drought year recorded in Texas since
1895. TCEQ’s modeling also used some
different emissions estimates for the
base year and future year 2023
emissions, including different future
year emissions for EGUs. There were
also some differences in methods used
in the model results analysis and the
model performance evaluation. TCEQ
also used a different methodology than
the EPA to identify monitors projected
to be maintenance receptors in 2023.
TCEQ used only the most recent DV
containing the base year 2012, (i.e., the
monitored DV for 2012–2014), to project
a 2023 ‘‘maintenance DV’’ for assessing
whether a monitor would have
maintenance issues. The EPA’s
methodology uses the maximum of the
three consecutive regulatory DVs
containing the base year, which is the
highest monitored DV from among the
three DVs that contain the 2011 base
year (i.e., the 2009–2011 DV, 2010–2012
DV or and 2011–2013 DV that all
contain modeled base year of 2011), to
project a 2023 maximum DV for
9825
assessing whether a monitor would have
maintenance issues. Texas explained
that it chose to define maintenance
receptors in this way to capture more
recent emission reductions. The SIP
submittal also included a discussion of
why TCEQ believes their approach for
identifying maintenance receptors is
appropriate. The TCEQ modeling and
differences with the EPA modeling is
discussed in detail in the EPA Region 6
TSD for this action.
Based on their modeling, TCEQ
provided: (1) A table of downwind
receptors projected to be in
nonattainment of the 2015 ozone
NAAQS in 2023 and have a contribution
from Texas emissions at a threshold of
0.7 ppb or greater and (2) a table of
downwind maintenance receptors
projected to have problems attaining
and maintaining the 2015 ozone
NAAQS in 2023 and have a contribution
from Texas emissions at a threshold of
0.7 ppb or greater. TCEQ identified
these receptors for further analysis. The
nonattainment and maintenance
receptors provided by TCEQ are listed
in Table TX–1. TCEQ noted that except
for Arapahoe County, CO (Monitor ID.
80050002) all the maintenance receptors
are also nonattainment receptors.
TABLE TX–1—PROJECTED 2023 NONATTAINMENT AND MAINTENANCE RECEPTORS IDENTIFIED BY TCEQ MODELING
USING 2012 BASE YEAR
2023
average DV
(ppb)
Receptor
(site ID, county, state)
80350004,
80590006,
80590011,
80690011,
80050002,
40038001,
60371201,
60371701,
60376012,
60658001,
60658005,
60710001,
60710306,
60711004,
60714001,
60714003,
Douglas, CO ..............................................................................................................
Jefferson, CO ............................................................................................................
Jefferson, CO ............................................................................................................
Larimer, CO ...............................................................................................................
Arapahoe, CO ............................................................................................................
Cochise, AZ ...............................................................................................................
Los Angeles, CA ........................................................................................................
Los Angeles, CA ........................................................................................................
Los Angeles, CA ........................................................................................................
Riverside, CA .............................................................................................................
Riverside, CA .............................................................................................................
San Bernardino, CA ..................................................................................................
San Bernardino, CA ..................................................................................................
San Bernardino, CA ..................................................................................................
San Bernardino, CA ..................................................................................................
San Bernardino, CA ..................................................................................................
73
72
71
72
*70
71
80
80
87
88
84
71
76
91
82
94
2023
maintenance
DV
(ppb) (TCEQ
method)
72
73
71
71
71
**69
78
82
86
85
83
72
77
90
79
91
Texas
contribution
(ppb)
1.42
1.26
1.26
1.22
1.15
1.06
0.76
0.72
0.9
0.73
0.71
0.84
0.81
0.88
0.86
0.74
lotter on DSK11XQN23PROD with PROPOSALS2
* TCEQ did not include this value in their SIP narrative (this cell was blank). The EPA obtained this value from data that was in TCEQ’s
spreadsheet of future 2023 DVs with state contributions.
** TCEQ did not provide this calculation. The EPA used TCEQ’s modeling information to calculate this value using the Relative Response Factor in TCEQ spreadsheet of future 2023 DVs with state contributions and the monitor’s 2012–2014 DV (0.983 X 71 ppb, truncation applied).
TCEQ also noted that in the EPA’s
2017 Transport NODA, the EPA’s
modeling linked Texas to six receptors
based on the receptors being identified
as nonattainment or maintenance
receptors and based on a 0.7 ppb
contribution threshold. TCEQ provided
a table of those monitors along with the
EPA and TCEQ modeling results for
95 ‘‘EPA Region 6 2015 8-Hour Ozone Transport
SIP Proposal Technical Support Document’’ (EPA
Region 6 2015 Ozone Transport SIP TSD.pdf)
included in Docket ID No. EPA–R06–OAR–2021–
0801.
96 The NODA and the October 2017 modeling are
discussed in Section I.C of this action.
VerDate Sep<11>2014
20:06 Feb 18, 2022
Jkt 256001
PO 00000
Frm 00029
Fmt 4701
Sfmt 4702
E:\FR\FM\22FEP2.SGM
22FEP2
9826
Federal Register / Vol. 87, No. 35 / Tuesday, February 22, 2022 / Proposed Rules
those receptors (Table TX–2).97 TCEQ
stated that the differences are due to
changes the TCEQ made to modeling
inputs (primarily the different base year
of 2012 versus the EPA’s 2011),
analysis, and methodologies (primarily
TCEQ’s alternate maintenance receptor
methodology), see the EPA Region 6
TSD included in the Regional docket for
this action (Docket ID No. EPA–R06–
OAR–2021–0801) for more details. With
exception of the Jefferson County, CO
receptor (Monitor ID. 80590011) TCEQ
did not further review its linkages to
any of the receptors in Table TX–2.
TABLE TX–2—TCEQ INFORMATION ON RECEPTORS LINKED TO TEXAS BY EPA MODELING IN THE TRANSPORT NODA
PUBLISHED ON JANUARY 6, 2017
EPA 2023
average DV
(ppb)
Receptor
(site ID, county, state)
260050003, Allegan, MI ...................................................................................
551170006, Sheboygan, WI ............................................................................
240251001, Harford, MD .................................................................................
360850067, Richmond, NY .............................................................................
361030002, Suffolk, NY ...................................................................................
80590011, Jefferson, CO ................................................................................
TCEQ then used a weight of evidence
approach to assess whether emissions
from Texas contribute significantly to
nonattainment or interfere with
maintenance at the receptors listed in
Table TX–1. TCEQ stated that the Texas
contribution to a receptor should be
deemed ‘‘significant’’ only if there is a
persistent and consistent pattern of
contribution on several days with
elevated ozone. Consideration was given
to factors such as DV trends, number of
elevated ozone days, back trajectory
analysis on elevated ozone days,
modeled concentrations on future
expected elevated ozone days, total
interstate contributions at tagged
monitors, and responsiveness of ozone
to emissions from Texas. Based on their
assessment, TCEQ concluded that
emissions from Texas do not contribute
significantly to nonattainment or
interfere with maintenance of the 2015
ozone NAAQS at any downwind
monitors. Our evaluation of the TCEQ
submission is further discussed in
Section V.B and in the EPA Region 6
TSD for this action.
lotter on DSK11XQN23PROD with PROPOSALS2
B. EPA Evaluation of the TCEQ SIP
Submission
Based on the EPA’s evaluation of the
SIP submission, the EPA is proposing to
find that TCEQ’s August 17, 2018, SIP
submission does not meet the State’s
obligations with respect to prohibiting
emissions that contribute significantly
to nonattainment or interfere with
maintenance of the 2015 ozone NAAQS
in any other state.
1. Evaluation of Information Provided
by TCEQ Regarding Step 1
As explained in Section I of this
action, at Step 1 of the 4-Step interstate
transport framework, the EPA identifies
97 TCEQ
SIP Submission, at page 3–49 (Table 3–
68.8
71.0
71.3
71.2
71.3
69.7
monitoring sites that are projected to
have problems attaining and/or
maintaining the NAAQS (i.e.,
nonattainment and maintenance
receptors). In executing this step, TCEQ
elected to rely on their own modeling
and methodology for identifying
receptors. The EPA is evaluating the
TCEQ’s modeling and methodology here
at Step 1.
i. Evaluation of TCEQ’s Methodology for
Identifying Maintenance Receptors
As discussed in Section V.A of this
action, in addition to the use of an
alternative modeling platform, TCEQ
also created its own method for
identifying maintenance receptors.
TCEQ has not adequately explained or
justified how its method for identifying
maintenance receptors reasonably
identifies areas that will have difficulty
maintaining the NAAQS. The EPA
proposes to find that TCEQ has not
provided a sufficient technical basis for
how its chosen methodology gives
meaning to the CAA’s instruction that
states submit good neighbor SIPs that
prohibit their states’ emissions from
interfering with the maintenance of the
NAAQS in another state.
In North Carolina v. EPA, 531 F.3d
896, 909–11 (D.C. Cir. 2008), the D.C.
Circuit rejected the EPA’s CAIR on the
basis that the EPA had not adequately
given meaning to the phrase ‘‘interfere
with maintenance’’ in the good neighbor
provision. Specifically, North Carolina
argued that it had counties that were
projected to attain the NAAQS in the
future analytic year but were at risk of
falling back into nonattainment due to
interference from upwind sources,
particularly given year-to-year
variability in ozone levels. The court
agreed, holding that the EPA’s rule did
98 See
FN 8.
EPA Texas
contribution
(ppb)
2.49
1.92
0.91
0.77
0.71
1.03
20:06 Feb 18, 2022
Jkt 256001
PO 00000
Frm 00030
99 See
Fmt 4701
Sfmt 4702
71
70
65
62
67
71
TCEQ Texas
contribution
(ppb)
0.59
0.73
0.69
0.67
0.63
1.26
not adequately protect ‘‘[a]reas that find
themselves barely meeting attainment.’’
Id. at 910. Consequently, the EPA has
developed a methodology, as described
elsewhere in this action and used in its
2011 CSAPR and its 2016 CSAPR
Update and Revised CSAPR Update, for
identifying areas that may struggle to
maintain the NAAQS. See 76 FR at
48227–28. The EPA’s approach to
addressing maintenance receptors was
upheld in the EME Homer City
litigation. See 795 F.3d 118, 136–37. It
was also upheld in Wisconsin. 938 F.3d
at 325–26. In Wisconsin, the court noted
that four upwind states were linked
only to maintenance receptors and
rejected the argument that application of
the same control level as the EPA
imposes for those states linked to
nonattainment receptors was
unreasonable or unlawful absent a
particularized showing of overcontrol.
Id. at 327.
To explain the differences between
TCEQ’s and the EPA’s methodology for
identifying maintenance receptors, it is
helpful to provide some additional
context of how the EPA projects future
air quality. The EPA’s air quality
modeling guidance has long
recommended developing a base design
value (DV) 98 (i.e., the design value that
will be used as a starting point to model
and analyze for purposes of projecting
future air quality concentrations) that is
the average of three DVs spanning a
five-year period, centered around one
year for which an emissions inventory
will be submitted (e.g., if 2011 was the
base emissions inventory year, a state
would use monitored values from 2009–
2011, 2010–2012, 2011–2013 as the
starting point for projecting air quality
concentrations in future years).99 The
FN 73.
12).
VerDate Sep<11>2014
TCEQ 2023
average DV
(ppb)
E:\FR\FM\22FEP2.SGM
22FEP2
lotter on DSK11XQN23PROD with PROPOSALS2
Federal Register / Vol. 87, No. 35 / Tuesday, February 22, 2022 / Proposed Rules
average of these three DVs is then
multiplied by a relative response factor
(RRF) 100 to generate an average DV for
the future year. If a receptor’s average
future year DV is greater than or equal
to the level of the NAAQS, and the
receptor has recent monitored data that
violates the NAAQS, that receptor is
considered a ‘‘nonattainment’’ receptor
at Step 1. To identify maintenance
receptors, the EPA’s methodology looks
to the highest DV of the three DVs used
to calculate the 5-year weighted average
design value (e.g., in the 2011 example,
if 2009–2011 had the highest design
value of 2009–2011, 2010–2012, and
2011–2013). The EPA then applies the
same relative response factor to that
highest design value to generate a
projected future maximum design value.
Where a receptor’s maximum design
value exceeds the level of the NAAQS,
the EPA has deemed those receptors to
be ‘‘maintenance’’ receptors. This
methodology was designed to address
the D.C. Circuit’s holding that the CAA’s
‘‘interference with maintenance’’ prong
requires states and the EPA to protect
areas that may struggle with
maintaining the standard in the face of
inter-annual variability in ozoneconducive conditions.
In its modeling, TCEQ adopted an
identical approach to the EPA’s for
identifying nonattainment receptors—it
looked at three sets of DVs over a fiveyear period and averaged those DVs to
generate a base year DV. TCEQ then
applied a relative response factor to that
base year design value to project a
receptor’s average design value in the
future year. For its maintenance
receptors, however, TCEQ used only the
most recent design value of the set of
three DVs, regardless of whether the
most recent design value was highest or
lowest, instead of considering
variability in conditions over a five-year
period, or using the highest DV of the
three DVs making up the base year
design value. TCEQ’s proffered
explanation for using the most recent
DV to identify maintenance receptors
was that the latest DV ‘‘takes into
consideration . . . any emissions
reductions that might have
occurred.’’ 101 However, TCEQ in its
submission does not explain how this
methodology takes into account
meteorological variability in identifying
those areas that may be meeting the
NAAQS or that may be projected to
meet the NAAQS but may nevertheless
struggle to maintain the NAAQS.
TCEQ argued that the 3-year DV used
includes some meteorological
100 See
FN 53.
101 TCEQ SIP submission at 3–39 to 3–40.
VerDate Sep<11>2014
20:06 Feb 18, 2022
Jkt 256001
variability. Unfortunately, the three
years of variation that TCEQ accounted
for is already built into the structure of
the standard. Thus, the TCEQ method
gave no consideration to the variability
between calculated DVs which provides
a direct indication of the difficulty a
receptor will have in maintaining the
standard. In other words, to determine
whether a receptor will have difficulty
maintaining the standard, one must
consider the variation in the metric that
will be used to determine compliance
with the standard. An indication of the
variability of a metric cannot be
determined by only considering a single
estimate of that metric.
TCEQ’s stated purpose in using the
most recent DV was to capture more
recent emissions reductions. TCEQ’s
methodology, however, limits receptors
which could be identified as
maintenance receptors, compared to the
EPA’s methodology largely because it
only looks at one design value period
rather than selecting the maximum of
the three DV periods EPA’s
methodology considers. Thus, TCEQ’s
methodology greatly reduces the
probability that meteorological
conditions which make it difficult to
maintain the standard will be
considered. As discussed further below,
the effects of emissions trends are
already captured through other aspects
of the methodology to identify
receptors. So, in trying to give more
weight to emission reductions, by
selecting only one design value (2012–
2014) for its base year, TCEQ’s
methodology did not give any
consideration to interannual variability
in ozone-conducive meteorology as does
the EPA’s method.
The EPA’s methodology, using the
maximum DV which accounts for the
variability in ozone concentrations and
DVs due to changes in meteorology over
the five years of the base year DV
period, was designed to identify those
areas that might struggle to maintain the
NAAQS in particularly ozone conducive
conditions. TCEQ claimed that the
EPA’s method undervalues changes in
air quality due to emission reductions
and overvalues changes due to variation
in meteorology. TCEQ pointed out that
emissions nationwide are generally
trending downward as a result of
Federal motor vehicle standards and
other technological improvements. The
EPA agrees that ozone levels generally
trend downward, but there is not a
steady decline from year to year in
ozone concentrations. Rather, ozone
levels tend to vary from year to year
with some years showing an increase
instead of a decrease mainly due to
inter-annual variability in ozone-
PO 00000
Frm 00031
Fmt 4701
Sfmt 4702
9827
conducive meteorology.102 The
variation of DVs at individual monitors
from year to year can be significant,
even where emissions trend
downwards. The EPA also assessed a
number of monitored DV trends that
were provided in TCEQ’s SIP
submission and previous TCEQ
attainment demonstration SIPs
indicating that there are at times large
annual fluctuations upward from year to
year in monitored DVs (sometimes 2–3
ppb increase in one year) that are due
to variations in meteorology.103 This is
precisely why it is important to consider
highly variable meteorology and its
influence on DVs—the issue at the heart
of the D.C. Circuit’s finding on
‘‘interference with maintenance’’ in
North Carolina. Areas that are required
under the Act to attain by an attainment
date may fail to attain because of a
combination of both local emissions,
upwind emissions, and ozone
conducive meteorology, among other
factors. The North Carolina decision
made clear that in interpreting the good
neighbor provision, upwind state and
the EPA obligations to reduce emissions
must account for variable conditions
that could cause an area that is
sometimes attaining the NAAQS to fall
out of attainment. See also Wisconsin,
938 F.3d at 327 (‘‘Variations in
atmospheric conditions and weather
patterns can bring maintenance
receptors into nonattainment even
without elevated emissions.’’).
In addition, TCEQ claimed that its use
of the 2012–2014 DV (i.e., the most
recent in the 5-year base period it
examined) is more reliable than the
EPA’s method, because that more recent
DV accounts for both emission
reductions and because there is a
shorter interval between the monitored
DV and the projected DV. As we note
elsewhere, the TCEQ’s base year
modeled inventory is 2012 emissions
and the TCEQ’s model projections for
2023 include the expected emission
reductions from 2012 thru 2014 and to
2023. By just using the 2012–2014 DV
data, TCEQ claimed they are giving
weight to emission reductions during
the final base years where EPA’s method
does not. The effect of emission
reductions, however, is already factored
in the method since the modeling
projection to 2023 is explicitly designed
to project the changes in ozone due to
emission reductions from the 2012 base
year emission levels. So, in fact, the
EPA method does give weight to
emission reductions. Furthermore, since
102 See EPA Region 6 TSD, included in Docket ID
No. EPA–R06–OAR–2021–0801.
103 Id.
E:\FR\FM\22FEP2.SGM
22FEP2
lotter on DSK11XQN23PROD with PROPOSALS2
9828
Federal Register / Vol. 87, No. 35 / Tuesday, February 22, 2022 / Proposed Rules
TCEQ agrees that the average of the DVs
based on 2010–2014 ozone levels are
reliable enough to use in the
identification of nonattainment
receptors, it is unclear how the 2012–
2014 period is deemed more reliable for
the maintenance test since the modeled
emissions are still for 2012. We also
note, as discussed throughout this
action, the EPA has updated its
modeling to use a 2016 base year—that
is, a five year period spanning 2014–
2018, and applied its methodology for
defining maintenance receptors using
that five year base period. Using a more
recent base period (EPA’s 2016v2)
provides the most recent design values,
shorter period of projection (2016 to
2023 versus a 2011 or 2012 base year)
and a more accurate basis for
projections of future air quality. We note
that the EPA undertook a large
collaborative multi-year effort with
states (including TCEQ) and other
stakeholders input and review in
developing the 2016v2 emission
inventories. By virtue of this update,
any monitored DV used by the EPA to
identify maintenance receptors in this
action accounts for more recent
emission reductions and provides a
shorter interval between base year
monitored DV and the projected future
analytic year.
As discussed further in the EPA
Region 6 TSD 104 for this action, the EPA
has reviewed the set of 21 receptors for
which Texas had contributions of 0.7
ppb or more in the EPA’s 2016 base year
modeling analyses, or TCEQ’s modeling
(2012 base year), and evaluated the
results of using TCEQ’s alternate
maintenance methodology. For these 21
receptors, TCEQ’s method resulted in 15
of the 21 2023 maintenance DVs
predicted to be lower than the 2023
nonattainment DVs from the
nonattainment methodology that uses
the 5-year center weighted average. Of
these 15 receptors, three receptors have
2023 maintenance DVs that are 3 ppb
lower, five receptors have 2023
maintenance DVs that are 2 ppb lower,
and seven receptors have 2023
maintenance DVs that are 1 ppb lower.
In comparison, using the EPA’s
maintenance methodology results in all
21 2023 maintenance DVs being equal
or up to 4 ppb higher than the 2023
nonattainment DVs. Again, the EPA
uses the average of the three DVs that
contain the base year modeled for the
nonattainment methodology and the
104 ‘‘EPA Region 6 2015 8-Hour Ozone Transport
SIP Proposal Technical Support Document’’ (EPA
Region 6 2015 Ozone Transport SIP TSD.pdf)
included in Docket ID No. EPA–R06–OAR–2021–
0801.
VerDate Sep<11>2014
20:06 Feb 18, 2022
Jkt 256001
maximum of these three DVs for the
maintenance methodology. Because
TCEQ’s maintenance methodology of
just using the most recent DV (2012–
2014 DV) often results in maintenance
DVs lower than the 2023 nonattainment
DVs methodology results, the EPA finds
that the TCEQ methodology is not
adequately identifying conditions when
a receptor would have more difficulty
maintaining the standard. In fact, the
TCEQ’s method also identified one
receptor in their SIP submission as a
nonattainment receptor in 2023 that
would not have been identified as a
maintenance receptor, which further
highlights the concern that TCEQ’s
method did not adequately identify
areas that may struggle to maintain the
standard. TCEQ did not address
whether the three years that comprise
the most recent design value (i.e., 2012,
2013, and 2014) had meteorological
conditions highly conducive for
formation of high ozone concentrations
and thus would be an appropriate time
period to assess whether area could
have difficulty maintaining the standard
and the EPA’s analysis confirms that
this time period is not highly conducive
to ozone formation, at least for many
receptors. The consequence of TCEQ’s
maintenance method is that it often
results in lower DVs than the
nonattainment test as demonstrated by
our analysis, which indicates that it is
often not considering conditions when
an area would have difficulty
maintaining the standard. It is also
unreasonable to have a test that would
not identify nonattainment receptors
also as maintenance receptors.
TCEQ also made several additional
assertions in support of their conclusion
that their method for identifying
maintenance receptors was the better
reading of the CAA, compared to the
EPA’s. TCEQ claimed that its approach
was more consistent with the CAA’s
concept of maintenance as areas that
were formerly nonattainment and that
have since attained and will continue to
maintain by accounting for: (1)
Emissions reductions occurring in the
later design values of the base DV
period; (2) ‘‘commitments regarding
contingency measures to address future
emission reductions;’’ and (3) the
impact of any maintenance plans that
are in place. TCEQ also asserted that the
EPA’s approach conflates the likelihood
of attaining the standard in a future year
and the ability of an attainment monitor
to maintain that attainment status.
Specifically, TCEQ argued that because
any remedies devised to address
nonattainment monitors would have to
apply to maintenance monitors, a
PO 00000
Frm 00032
Fmt 4701
Sfmt 4702
practical consequence of the EPA’s
approach is that it could lead to overcontrol and that it might require upwind
states to consider or implement controls
when the downwind state in which the
monitor is located does not have any
obligations to control local emissions.
TCEQ argued that this ‘‘conflation’’ of
nonattainment and maintenance results
in there being no independent meaning
to ‘‘maintenance.’’
With respect to the first of these
assertions from TCEQ, we note that
TCEQ’s methodology for identifying
receptors (like the EPA’s) is entirely
distinct from ozone designations under
the Clean Air Act; neither TCEQ nor the
EPA take current or presumed future
designations of areas into account, and
any implementation requirements like a
maintenance plan under CAA section
175A, in identifying receptors. TCEQ’s’
discussion, therefore, of maintenance
plan contingency measures or
maintenance plans generally is
irrelevant and misplaced. None of the
areas to which Texas is linked in the
EPA 2016v2 modeling has been
redesignated to attainment for the 2015
ozone NAAQS, and none of the areas to
which Texas is linked in its own
modeling has been redesignated to
attainment for that NAAQS. We also fail
to see how TCEQ’s approach to
identifying maintenance receptors
differs in any relevant respect from the
EPA’s approach with regard to the
alleged ‘‘conflation’’ of projecting
attainment in a future year rather than
the ability of an attainment receptor to
maintain attainment. Both TCEQ and
the EPA identify maintenance receptors
based on projections of air quality in a
future year to determine whether the
receptor will have difficulty attaining or
maintaining the standard. TCEQ’s
arguments about overcontrol based on
the application of a uniform remedy to
states linked to both nonattainment and
maintenance receptors were also not
germane; in this case, TCEQ had
identified no remedy to apply
whatsoever because it had failed to
identify that the emissions from Texas
cause a problem in the first instance.
The D.C. Circuit has already rejected the
idea that the application of a uniform
control to both nonattainment and
maintenance receptors is on its face
overcontrol or impermissible under the
interstate transport provision. See
Wisconsin, 938 F.3d at 327. Based on
our evaluation of TCEQ’s approach to
identify maintenance receptors for 2023,
we propose to find the State’s approach
is inadequate as it does not sufficiently
identify maintenance receptors. Further,
TCEQ had not explained how its
E:\FR\FM\22FEP2.SGM
22FEP2
9829
Federal Register / Vol. 87, No. 35 / Tuesday, February 22, 2022 / Proposed Rules
approach meets the statutory
requirement to address areas that, even
if meeting the NAAQS, may struggle to
maintain the standard in years where
conditions are conducive to ozone
formation. Rather, the TCEQ had created
its own approach to identify these areas
that they describe as designed to
account for the most emission
reductions possible—i.e., the most
recent DV of the three under analysis;
an approach that likely under-identifies
areas that will struggle to maintain the
NAAQS and that certainly is not
designed to capture potential air quality
problems.
ii. Evaluation of the TCEQ Modeling
As discussed in Section V.A of this
action, TCEQ conducted regional
photochemical modeling to identify
nonattainment and maintenance
receptors in 2023 using a 2012 base
year. As discussed further in the EPA
Region 6 TSD, we have several concerns
with the reliability of TCEQ’s modeling
results. States are free to develop their
own modeling, but that modeling must
be technically supportable, and the EPA
is obligated to assess and evaluate the
reliability of that technical
demonstration when determining
whether the Act’s requirements are met.
The TCEQ’s modeling underestimates
future ozone levels. When the TCEQ
2023 projected concentrations are
compared to 2020 and preliminary 2021
monitor values, it is clear that the TCEQ
modeling is projecting an unusual
decline in ozone levels without there
being an unusual level of emission
reductions to support the decline. The
EPA compared recent monitoring values
and reasonably anticipated decreases in
DVs by 2023 both within Texas and in
other parts of the country. These
underestimations likely result in
TCEQ’s modeling not adequately
identifying nonattainment and/or
maintenance receptors in 2023. These
underestimations also result in smaller
projected contributions from Texas
emissions to downwind states. See EPA
Region 6 TSD for full analysis details.
One analysis included in the EPA
Region 6 TSD examined the average
amount of improvement that would
have to occur for the 9 monitors with
the highest measured design values in
the Dallas-Ft. Worth and HoustonGalveston-Brazoria nonattainment areas
(those with an observed 2018–2020 DV
of 74 ppb or greater) to reach the level
of ozone projected by the TCEQ
modeling. The average decrease needed
by 2023 to meet TCEQ’s 2023 projected
DVs is 7.56 ppb. Improvements of this
magnitude do not occur in three years
unless there is an unusually large
change in emissions or a large change in
meteorological conduciveness for ozone
generation. TCEQ did not identify any
large emission reductions not already
accounted for in the modeling to be
implemented in the 2021–2023
timeframe nor is the EPA aware of such
a change. This information supports our
finding that that TCEQ’s modeling is
underestimating future ozone levels in
the two nonattainment areas in Texas
that make up a large proportion of the
total ozone and a large portion of
emissions of ozone pre-cursors that
transport to downwind areas. This
underestimation of future year ozone
levels from Texas emissions can cause
both an underestimation of ozone in
downwind areas and also an
underestimation of Texas’s impact on
downwind State’s ozone nonattainment
and maintenance receptors.
TCEQ’s modeling also underestimates
2023 ozone levels outside of the State of
Texas including areas of interest in
California, Colorado and the Midwest
Region (Illinois, Wisconsin, and
Michigan). The EPA discusses this
underprediction for all of these areas in
the EPA Region 6 TSD. In Table TX–3,
we present only the results for the
Midwest Region along with the EPA’s
modeling prediction. We note that
TCEQ’s 2023 modeled DVs are
significantly lower than the EPA’s 2023
modeled DVs. The table also provides
recent monitored 2020 DVs and
preliminary 2021 DVs, which shows
that recent monitored ozone
concentrations are significantly higher
than TCEQ’s modeling projected for
2023. TCEQ’s ozone DVs for these
receptors would need to drop on the
order of 7–15 ppb in two to three years
for TCEQ’s projections to bear out. As
noted previously, this would require an
unusual amount of emission reductions
without any control measures identified
of sufficient magnitude. We note that
the EPA’s projected 2023 ozone DVs
based on EPA 2016v2 modeling show
ozone DVs that are also lower than
recent monitoring data. However, EPA
2016v2 modeling projections are much
closer to anticipated 2023 ozone levels
as compared to TCEQ’s modeling. This
indicates that the EPA’s modeling is
more accurate in identifying
nonattainment and/or maintenance
receptors in the Midwest Region. While
the TCEQ modeling projects much
lower overall ozone levels for the
Midwest Region in 2023, the modeling
does tend to corroborate the projected
amount emissions that Texas may be
contributing to projected ozone levels at
5 of the 7 nonattainment and
maintenance receptors identified in the
EPA’s modeling.105 Thus, despite the
differences in identification of
nonattainment and maintenance
receptors, both sets of modeling indicate
that Texas’s contribution to receptors in
the Midwest Region are greater than 0.7
ppb (i.e., 1 percent of the 2015 ozone
NAAQS). Table TX–3 provides
information on those receptors,
including the amount of contribution
attributed to emissions from Texas
based on EPA’s 2016v2 modeling and
TCEQ’s modeling. Despite the
differences in identification of
nonattainment and maintenance
receptors, both sets of modeling indicate
that Texas’s contribution to receptors in
the Midwest are greater than 0.7 ppb
(i.e., 1 percent of the 2015 ozone
NAAQS).
TABLE TX–3—EPA AND TCEQ MODELING RESULTS FOR DOWNWIND RECEPTORS IDENTIFIED BY EPA 2016V2 MODELING
lotter on DSK11XQN23PROD with PROPOSALS2
Receptor
(site ID, county, state)
170310001,
170310032,
170314201,
170317002,
Cook,
Cook,
Cook,
Cook,
IL
IL
IL
IL
...........
...........
...........
...........
2023 nonattainment/
maintenance
(EPA 2016v2)
Maintenance
Maintenance
Maintenance
Maintenance
105 We note that for two of the Wisconsin
receptors, TCEQ’s modeling does not provide
VerDate Sep<11>2014
20:06 Feb 18, 2022
Jkt 256001
.........................
.........................
.........................
.........................
EPA: 2023
average DV/
maximum DV
(ppb)
69.6/73.4
69.8/72.4
69.9/73.4
70.1/73.0
TCEQ: 2023
average DV/
maintenance
DV
(ppb)*
60/58
68/66
64/62
66/65
Monitored
2018–2020
DV/preliminary
2019–2021
DV**
(ppb)
............
............
............
............
75/71
74/75
77/74
75/73
information to generate 2023 DVs, so only 5 of the
7 monitors can be compared.
PO 00000
Frm 00033
Fmt 4701
Sfmt 4702
E:\FR\FM\22FEP2.SGM
22FEP2
EPA: Texas
contribution
(ppb)
0.86
1.46
1.15
1.58
TCEQ: Texas
contribution
(ppb)
1.6.
1.31.
1.25.
1.22.
9830
Federal Register / Vol. 87, No. 35 / Tuesday, February 22, 2022 / Proposed Rules
TABLE TX–3—EPA AND TCEQ MODELING RESULTS FOR DOWNWIND RECEPTORS IDENTIFIED BY EPA 2016V2
MODELING—Continued
Receptor
(site ID, county, state)
2023 nonattainment/
maintenance
(EPA 2016v2)
550590019, Kenosha, WI ....
550590025, Kenosha, WI ....
551010020, Racine, WI .......
Nonattainment .......................
Maintenance .........................
Nonattainment .......................
EPA: 2023
average DV/
maximum DV
(ppb)
72.8/73.7
69.2/72.3
71.3/73.2
TCEQ: 2023
average DV/
maintenance
DV
(ppb)*
Monitored
2018–2020
DV/preliminary
2019–2021
DV**
(ppb)
67/66 ............
No data*** ....
No data*** ....
74/74
74/72
73/73
EPA: Texas
contribution
(ppb)
1.72
1.81
1.34
TCEQ: Texas
contribution
(ppb)
1.44.
No data.***
No data.***
lotter on DSK11XQN23PROD with PROPOSALS2
* TCEQ did not provide sufficient data and analysis of the meteorology for the 2010–2014 period to support their claim that 2012–2014 period
was a worst-case combination of meteorology compared to the 2010–2012 and 2011–2013 periods. If the future DV projected from this highest
value is below the standard, one can be reasonably certain the receptor will not have difficulty maintaining the standard and, as such, upwind
states will not interfere with maintenance in downwind states. Because the TCEQ method only looks at one DV and does not account for the variability in DVs due to meteorological conditions, it is less likely to identify maintenance receptors than the EPA method. See https://www.epa.gov/
air-trends/air-quality-design-values
** Preliminary 2019–2021 DVs. Monitoring data from the EPA’s Air Quality System (AQS) (https://www.epa.gov/aqs). 2021 monitoring data is
preliminary and still has to undergo Quality Assurance/Quality Control analysis and be certified by the State of Texas, submitted to the EPA, and
reviewed and concurred on by EPA. 2018–2020 DVs are 72 ppb and 73 ppb at the Denton County and Tarrant County monitors/receptors respectively. Preliminary 2019–2021 DVs are 74 ppb and 72 ppb at the Denton County and Tarrant County monitors/receptors respectively.
*** Kenosha, WI Monitor ID. 550590025 was installed and began operating May 13, 2013, so the first three year DV available is 2013–2015.
Racine, WI Monitor ID. 551010020 was installed in April 14, 2014 so the first three year DV available is 2015–2017. TCEQ’s modeling used
monitored DV data for 2010–2012, 2011–2013, and 2012–2014 to project to the future year. Since these monitors do not have valid DVs for
these periods, TCEQ’s modeling can’t be used to project 2023 values and identify if they would be nonattainment or maintenance receptors.
The EPA investigated TCEQs
modeling and the underestimation for
the future year. See the EPA Region 6
TSD for further information on our
review. Our review indicated some
underestimation bias in the base case
and general model performance
concerns but nothing that was a clear
cause of the much lower 2023 DVs that
TCEQ’s modeling is projecting. For the
EPA’s 2016 base year modeling, the EPA
undertook a large collaborative multiyear effort with states (including Texas)
and other stakeholder input in
developing the 2016 emission
inventories including 2016v2, so that
the EPA’s modeling would be based on
the best data available. Using a 2016
base year also provides a more recent
platform that shortens the number of
years to project emission changes,
reducing uncertainties in the 2023
projection compared to TCEQ’s
projection from a 2012 base to 2023 or
the EPA’s earlier 2011 base year
modeling. Use of a more recent 2016
base year also allows for the use of
monitored DVs from a more recent
period. The combination of these and
other issues discussed in the EPA
Region 6 TSD result in less model
uncertainty compared to TCEQ’s 2012
base year modeling and has provided a
better estimate of 2023 ozone levels and
therefore, we believe a more reliable
tool for predicting which areas of the
country will be nonattainment or have
difficulty maintaining the standard as
well as assessing contributions from
upwind states.
The EPA’s modeling using both 2011
and 2016 base year periods identified
that Texas was linked to nonattainment
VerDate Sep<11>2014
20:06 Feb 18, 2022
Jkt 256001
and/or maintenance receptors in 2023 in
the Midwest Region (Illinois,
Wisconsin, and Michigan), while
TCEQ’s modeling using a 2012 base year
indicated only linkages to western
receptors. As discussed above and in the
EPA Region 6 TSD, the TCEQ’s
modeling is underestimating projected
ozone levels in the Midwest Region for
2023. If TCEQ’s 2023 modeled DVs were
closer to recent observed monitoring
data and anticipated 2023 monitored
DVs, TCEQ would likely have also
identified nonattainment and/or
maintenance receptors in the Midwest
Region.
To summarize, TCEQ did its own
modeling at Step 1. Our analysis shows
that TCEQ’s modeling likely
underestimates ozone levels at potential
receptors and that TCEQ’s methodology
for identifying maintenance receptors
used to identify maintenance receptors
fails to reasonably identify areas that
will have difficulty maintaining the
NAAQS.
2. Evaluation of Information Provided
by TCEQ Regarding Step 2
TCEQ, like the EPA, used a 1 percent
of the ozone NAAQS (or 0.7 ppb) as the
‘‘linkage’’ threshold to identify states as
‘‘linked’’ for contributions it made to
areas with projected air quality
problems. Although TCEQ asserted that
the EPA treats the 1 percent threshold
as the threshold by which the EPA
determines ‘‘significant contribution’’
this is in fact incorrect. The EPA, like
TCEQ, uses the 1 percent contribution
threshold to identify those linkages
between a contributing upwind state
and a receptor projected to have air
PO 00000
Frm 00034
Fmt 4701
Sfmt 4702
quality problems that warrant further
review and additional analysis. We
therefore endorse TCEQ’ use of the 1
percent contribution threshold to
identify linkages requiring further
analysis. However, because we propose
to disapprove TCEQ’s identification of
nonattainment and/or maintenance
receptors (at Step 1) due to
underestimations in TCEQ’s modeling
and their unsupported methodology of
identifying maintenance receptors, their
submission as to Step 2 is also flawed.
We note, however, that even in its own
modeling, TCEQ has identified
nonattainment and/or maintenance
receptors to which it contributed more
than 1 percent of the NAAQS (i.e.,
identified linkages warranting
additional analysis at Step 3).
3. Results of the EPA’s Step 1 and Step
2 Modeling and Findings for Texas
As described in Section I and
elsewhere in this action, the EPA
performed air quality modeling using
the 2016v2 emissions platform to
project design values and contributions
for 2023. This data was examined to
determine if Texas contributes at or
above the threshold of 1 percent of the
2015 ozone NAAQS (0.70 ppb) to any
downwind nonattainment or
maintenance receptor. As shown in
Table TX–4, the data 106 indicate that in
2023, emissions from Texas are
projected to contribute greater than 1
percent of the standard to both
106 Design values and contributions at individual
monitoring sites nationwide are provided in the
file: ‘‘2016v2_DVs_state_contributions.xlsx’’, which
is included in docket ID No. EPA–HQ–OAR–2021–
0663.
E:\FR\FM\22FEP2.SGM
22FEP2
Federal Register / Vol. 87, No. 35 / Tuesday, February 22, 2022 / Proposed Rules
nonattainment and maintenance-only
receptors in the Chicago, IL–IN–WI
nonattainment area (4 Cook County, IL
receptors and 2 Kenosha County, WI
receptors) and the Milwaukee, WI
9831
nonattainment area (one Racine County
receptor).107
TABLE TX–4—PROJECTED NONATTAINMENT AND MAINTENANCE RECEPTORS WITH TEXAS LINKAGES BASED ON EPA
2016V2
Receptor
(site ID, county, state)
lotter on DSK11XQN23PROD with PROPOSALS2
170310001,
170310032,
170314201,
170317002,
550590019,
550590025,
551010020,
Nonattainment/maintenance
Cook, IL ......................................
Cook, IL ......................................
Cook, IL ......................................
Cook, IL ......................................
Kenosha, WI ...............................
Kenosha, WI ...............................
Racine, WI ..................................
2023
average DV
(ppb)
Maintenance ...................................................
Maintenance ...................................................
Maintenance ...................................................
Maintenance ...................................................
Nonattainment ................................................
Maintenance ...................................................
Nonattainment ................................................
69.6
69.8
69.9
70.1
72.8
69.2
71.3
2023
maximum DV
(ppb)
73.4
72.4
73.4
73.0
73.7
72.3
73.2
Texas
contribution
(ppb)
0.86
1.46
1.15
1.58
1.72
1.81
1.34
We recognize that the results of the
EPA (2011 and 2016 base year) and
TCEQ (2012 base year) modeling
indicated different receptors and
linkages at Steps 1 and 2 of the 4-Step
interstate transport framework. These
differing results regarding receptors and
linkages can be affected by the varying
meteorology from year to year, but we
do not think the differing results mean
that the modeling or the EPA or the
State’s methodology for identifying
receptors or linkages is inherently
unreliable. Rather, the three separate
modeling runs all indicated: (1) There
were receptors that would struggle with
nonattainment or maintenance in the
future; and (2) Texas was linked to some
set of these receptors, even if the
receptors and linkages differed from one
another in their specifics (e.g., a
different set of receptors were identified
to have nonattainment or maintenance
problems, or Texas was linked to
different receptors in one modeling run
versus another). These results indicate
that emissions from Texas were
substantial enough to generate linkages
at Steps 1 and 2 to some downwind
receptors, under varying assumptions
and meteorological conditions, even if
the precise set of linkages changed
between modeling runs. Under these
circumstances, we think it is
appropriate to proceed to a Step 3
analysis to determine what portion of
emissions from Texas should be deemed
‘‘significant.’’ In doing so, we are not
agreeing with the methods and
assumptions contained in TCEQ’s
modeling (see previous discussion and
the EPA Region 6 TSD included in the
docket for this proposal for further
discussion on evaluation of that
modeling), or that we consider our own
earlier modeling to be of equal
reliability relative to more recent
modeling. However, where alternative
or older modeling generated linkages,
even if those linkages differ from
linkages in the EPA’s most recent set of
modeling (EPA 2016v2), that
information provides further evidence,
not less, in support of a conclusion that
the State is required to proceed to Step
3 to further evaluate its emissions.
Therefore, based on the EPA’s
evaluation of the information submitted
by TCEQ and based on the EPA 2016v2
modeling results for 2023, the EPA
proposes to find that Texas 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.
At Step 3 of the 4-Step interstate
transport framework, a state’s emissions
are further evaluated, considering
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 effectively evaluate 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 approach (i.e.,
Step 3 of the 4-Step interstate transport
framework) when identifying emissions
contributions that the Agency has
determined to be ‘‘significant’’
(contribution to nonattainment 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. TCEQ did not demonstrate
such an analysis in their SIP
submission. We therefore propose that
TCEQ 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
Texas failed to do so.
Instead, as noted in Section V.A of
this action, TCEQ interpreted the Act’s
requirements as only requiring an
107 These modeling results are consistent with the
results of a prior round of 2023 modeling using the
2016v1 emissions platform which became available
to the public in the fall of 2020 in the Revised
CSAPR Update, as noted in Section I of this action.
That modeling showed that Texas had a maximum
contribution greater than 0.70 ppb to at least one
nonattainment or maintenance-only receptor in
2023. These modeling results are included in the
file ‘‘Ozone Design Values And Contributions
Revised CSAPR Update.xlsx’’ in Docket No. EPA–
HQ–OAR–2021–0663.
VerDate Sep<11>2014
20:06 Feb 18, 2022
Jkt 256001
4. Evaluation of Information Provided
by TCEQ Regarding Step 3
PO 00000
Frm 00035
Fmt 4701
Sfmt 4702
E:\FR\FM\22FEP2.SGM
22FEP2
lotter on DSK11XQN23PROD with PROPOSALS2
9832
Federal Register / Vol. 87, No. 35 / Tuesday, February 22, 2022 / Proposed Rules
analysis of emission reductions where
‘‘there is a persistent and consistent
pattern of contribution on several days
with elevated ozone.’’ TCEQ asserted
that it would make the determination of
whether such pattern existed based on
a weight-of-evidence approach that
takes into consideration air quality
factors such as: Current attainment
status of the monitors, design value
trends, the meteorological conditions
that lead to high ozone formation at the
monitor, the number of days with
elevated observed ozone, back
trajectories, Texas’ relative contribution
on modeled high ozone days, Texas’
contribution as part of the collective
interstate contribution to future
modeled DVs, alternate contribution
method analysis, and model sensitivity
runs to reductions of Texas’ emissions
on receptors. However, TCEQ stated that
it did not consider or analyze all factors
for every monitor. Thus, different
factors were analyzed for the receptors
in different regions (Colorado, Arizona,
and Southern California). The EPA has
reviewed the different factors that TCEQ
provided for each of the regions in the
EPA Region 6 TSD, but we will provide
a brief summary of the evaluation
below. TCEQ also asserted that use of
the 1 percent threshold as the ‘‘sole’’
definition of significant contribution for
the 2015 ozone NAAQS is
inappropriate. Based on the application
of selected factors for each of the
monitors to which TCEQ’s modeling
found that it was linked, TCEQ
concluded that none of its contributions
to any other states were significant.
As explained above, TCEQ has
mischaracterized the EPA’s
interpretation of the CAA in stating that
the EPA defines significant contribution
‘‘solely’’ using a 1 percent threshold.
The EPA, like TCEQ, uses the 1 percent
threshold to identify areas for further
analysis. The difference is that the EPA
in past analyses has examined potential
emission reductions in linked upwind
states and the air quality impacts at
downwind receptors that would result
from the implementation of those
reductions to assess which
contributions are ‘‘significant.’’ This
interpretation of significant
contribution, as discussed above, has
been upheld by the Supreme Court and
the D.C. Circuit.
As an initial matter, the EPA believes
source apportionment modeling, as
performed by the EPA and also by
TCEQ, to determine which states are
linked is an appropriate tool to identify
impacts that are persistent enough to
impact a downwind receptors ability to
attain or maintain the standard. This
approach is described in more detail
VerDate Sep<11>2014
20:06 Feb 18, 2022
Jkt 256001
above in Section II.B.4 of this action,
but, in summary, averages the
contributions from an upwind state for
up to 10 days, which is preferred, (but
a minimum 5 days) at a given receptor.
Given the ozone standard is an average
of the fourth high value from each of
three years, the EPA technique, also
used by Texas, is appropriate to identify
impacts of sufficient persistence to
impact a downwind receptor’s ability to
attain or maintain the standard.
The EPA reviewed TCEQ’s evaluation
of the current attainment status of the
monitors and design value trends, and
concludes, as described in more detail
in the EPA Region 6 TSD, that the
provided information does not support
the large decreases in ozone levels that
TCEQ’s modeling projects will occur by
2023. The analysis for California and
Colorado receptors provides evidence
that TCEQ’s photochemical modeling is
overestimating the ozone reductions
expected at these receptors between
2012 and 2023 and actually presents
evidence that more nonattainment and/
or maintenance receptors should have
been identified.
The EPA also reviewed the trends in
the number of high ozone days per year
provided by TCEQ for Colorado and
California. While this data supports that
the number of ozone exceedance days is
improving, neither the analysis of the
number of high ozone days in Colorado
or California provide any evidence to
refute the TCEQ’s photochemical
modeling results that show these areas
should be considered nonattainment
and/or maintenance receptors. TCEQs
modeling overestimates ozone
reductions yet still shows Texas linked
to receptors at both nonattainment and
maintenance levels in 2023.
The TCEQ cited a conceptual model
of ozone formation for areas in Southern
California. TCEQ indicated that
Southern California is isolated and
transport into the basin is unlikely on a
frequent basis, but this information does
not refute the TCEQ’s modeling. As
discussed in Section III.B.3 of this
action, photochemical modeling is the
most sophisticated tool available to
estimate future ozone levels and
contributions to those modeled future
ozone levels. Consideration of the
different processes that affect primary
and secondary pollutants at the regional
scale in different locations is
fundamental to understanding and
assessing the effects of emissions on air
quality concentrations. TCEQ’s
modeling showed transport at 10
monitors having contributions greater
than 0.7 ppb on average for the 5–10
days used in the modeling analyses.
Considering the form of the standard,
PO 00000
Frm 00036
Fmt 4701
Sfmt 4702
this is a sufficient number of days to
determine if an impact is persistent
enough to impact an area’s ability to
attain or maintain the standard.
TCEQ used the National Oceanic and
Atmospheric Administration (NOAA)
HYSPLIT 108 model to produce back
trajectories for all the monitored ozone
exceedance days (2007–2016) for the
five receptors in Colorado and 10
receptors in Southern California to
evaluate how many of the back
trajectories went through Texas. TCEQ
also used data from these back
trajectories to do an endpoint count
analysis. We note that we have several
concerns with how TCEQ performed the
back trajectories including start time
and heights, length (number of hours) of
the back trajectory, inappropriate
removal of some back trajectories based
on start height, center-line height touch
down, and trajectory center-line height
when over Texas, and inappropriate
counting of trajectories by not
considering that the center-line
represents the centerline of a much
wider area of air parcels that could have
reached the monitor/receptor. Due to
these concerns, as discussed in more
detail in the EPA Region 6 TSD, the EPA
finds the results of TCEQ’s back
trajectory and endpoint analysis flawed
(underestimates back trajectories that
reach Texas) and do not provide
evidence that refutes the TCEQ
photochemical modeling analysis
results.
We note that even valid back
trajectories are of limited use as
HYSPLIT simply estimates the path a
parcel of air backward in hourly steps
for a specified length of time. HYSPLIT
estimates the central path in both the
vertical and horizontal planes. The
HYSPLIT central path represents the
centerline with the understanding that
there are areas on each side horizontally
and vertically that also contribute to the
concentrations at the end point. The
horizontal and vertical areas that
potentially contribute to concentrations
at the endpoint (monitor) grow wider
from the centerline the further back in
time the trajectory goes. Therefore, a
HYSPLIT centerline does not have to
pass directly over emissions sources or
emission source areas, but merely
relatively near emission source areas for
those areas, to contribute to
concentrations at the trajectory
endpoint. The EPA relies on back
trajectory analysis as a corollary
analysis along with observation-based
meteorological wind fields at multiple
heights to examine the general
plausibility of the photochemical model
108 See
E:\FR\FM\22FEP2.SGM
FN 34.
22FEP2
lotter on DSK11XQN23PROD with PROPOSALS2
Federal Register / Vol. 87, No. 35 / Tuesday, February 22, 2022 / Proposed Rules
‘‘linkages.’’ Since the back trajectory
calculations do not account for any air
pollution formation, dispersion,
transformation, or removal processes as
influenced by emissions, chemistry,
deposition, etc., the trajectories cannot
be used to develop quantitative
contributions. Therefore, back
trajectories cannot be used to
quantitatively evaluate the magnitude of
the existing photochemical
contributions from upwind states to
downwind receptors. It is interesting to
note that TCEQ’s analysis of the back
trajectories indicates that the 2012
meteorology used by TCEQ seemed to
yield more back trajectories that reach
Texas than most years for many of the
Colorado monitors. This seems to be
consistent with TCEQ identifying
linkages to Colorado when the EPA’s
modeling of 2016 does not.
TCEQ performed an alternate
contribution analysis for the ten
California receptors and the five
Colorado receptors using all days
modeled in 2023 that had values over 70
ppb rather than focus on just the 5–10
highest values under the EPA’s
technique. Particularly for California,
this meant many more days could be
included in the average which had the
effect of showing a smaller estimated
contribution. We believe it is
appropriate to focus on the highest
values as these are the ones that
ultimately will have to be reduced for
the standard to be attained. As
discussed in the EPA Region 6 TSD, the
EPA’s review of TCEQ’s alternate
contribution method analysis for
California and Colorado receptors is that
it does not provide substantial evidence
that refutes the TCEQ’s photochemical
modeling analysis results, including the
contribution analysis using the EPA’s
contribution methodology.
TCEQ provided an analysis of
collective interstate contribution to the
2023 DV for the five Colorado and ten
California receptors. The collective
interstate contribution at tagged
Colorado receptors ranges from 9.32%
to 10.27%. The collective interstate
contribution at tagged California
receptors ranges from 3.2% to 4.58%.
TCEQ argues that these are small
percentages (Colorado and California)
and not as high as the collective
interstate contribution percentages the
EPA calculated for monitors in Eastern
States, which ranged from 17% to 67%.
TCEQ also notes that a significant
portion of the tagged Colorado monitors’
2023 modeled DVs is due to background
emissions (sum of contributions from to
biogenic, fires, and boundary
conditions). For the California receptors
TCEQ argues that these percentages are
VerDate Sep<11>2014
20:06 Feb 18, 2022
Jkt 256001
small compared to Intra-State
contribution.
As an initial matter, the EPA is not
solely relying on TCEQ’s findings of
linkages to Colorado and California but
is also relying on its own findings of
linkages to areas in the Midwest Region.
As such, TCEQ’s analysis of relative
contributions to Colorado and California
does not provide justification for not
addressing downwind impacts.
Nonetheless, EPA has found in the past
that certain California receptors are so
heavily impacted by local emissions,
and total upwind contribution is so low,
that those receptors may not be
considered to be affected by interstate
ozone transport. See 81 FR 15200 (Mar.
22, 2016). However, this is a narrow
circumstance that does not apply in the
vast majority of cases and has never
been applied outside of California. EPA
has previously found, for instance, that
receptors in Colorado are heavily
impacted by upwind-state contribution.
See 82 FR 9155 (Feb. 3, 2017); 81 FR
71991 (Oct. 19, 2016). EPA need not
draw any conclusions here regarding
whether the California sites TCEQ
identified should or should not be
considered receptors for ozone-transport
purposes. EPA affirms, contrary to
TCEQ’s suggestion, that the Colorado
receptors TCEQ analyzed are impacted
by upwind state contributions.
However, the EPA’s finding that Texas
is linked to receptors in other states is
based on still other linkages found in
EPA’s modeling to receptors in other
states, which are clearly impacted by
the collective contribution of multiple
upwind states, including Texas. Under
CAA section 110(a)(2)(D)(i)(I)
downwind states are not obligated to
reduce emissions on their own to
resolve nonattainment or maintenance
problems. Rather, states are obligated to
eliminate their own significant
contribution or interference with the
ability of other states to attain or
maintain the NAAQS.
TCEQ also performed photochemical
modeling analysis using the Direct
Decoupled Method (DDM) tool for
receptors in Colorado. DDM provides a
first derivative of the changes in ozone
(linear relationship where the DDM
value is the slope of the line for changes
in ozone) resulting from changes in NOX
emissions from all Texas’ NOX
emissions. The DDM modeling does
show some response to Texas NOX
emissions but from the scale it is hard
to discern the level of response but it
appears to be in the 0–2 ppb range in
general with some values in the 0.2 –2
ppb range for modeled values over 60
ppb. Since the modeling has
underprediction and underestimation
PO 00000
Frm 00037
Fmt 4701
Sfmt 4702
9833
issues, these values could be higher. Not
surprisingly, the DDM tool shows that
monitors in Colorado are much more
responsive to intra-state reductions than
reductions in Texas. That said, the
results of the DDM tool showing only a
relatively small response to reductions
is not inconsistent with the finding that
Texas emissions contribute significantly
to elevated readings in Colorado. As has
been discussed elsewhere, the EPA
believes a contribution of 1 percent of
the standard is an appropriate threshold
such that further analysis is warranted.
Overall, these additional analyses
performed by TCEQ do not provide
sufficient evidence to refute the
modeling results that TCEQ’s modeling
indicates downwind nonattainment
and/or maintenance receptors in
Colorado and Southern California are
impacted by Texas emissions and Texas’
contribution is 0.7 ppb or greater.109 In
fact, the monitored ozone design value
trends provide evidence that future year
modeled ozone levels are
underestimated by TCEQ’s modeling
and there are likely more receptors that
should have been identified with
additional potential linkages. Although
Texas asserted that its additional air
quality factor analysis is a permissible
way to interpret which contributions are
‘‘significant’’ because that analysis
examines whether there was a
‘‘persistent and consistent pattern of
contribution on several days with
elevated ozone’’ we find that such
pattern is already established by a
modeled linkage at Step 2.
In addition, EPA 2016v2 modeling
using 2016 base year meteorology
indicates linkages from Texas to
receptors in the Midwest Region but
does not indicate impacts from Texas
emissions on the Colorado and other
western receptors identified by TCEQ.
With a different base period such as
TCEQ’s 2012 base period meteorology
and the EPA’s 2016 base period
meteorology, it is not uncommon that
the potential downwind nonattainment
or maintenance receptors could change.
These differing results about receptors
and linkages can be affected by the
varying meteorology from year to year
and the selection of different base years,
but we do not think the differing results
mean that the modeling or the EPA
methodology for identifying receptors or
linkages is inherently unreliable. Rather,
these separate modeling runs indicated
(1) that there were receptors that would
109 TCEQ also identified a monitor in Cochise
County, Arizona (ID 40038001), but the monitor’s
recent DVs are below the NAAQS. From AQS, the
2014–2016 and 2015–2017 DVs are each 65 ppb;
2016–2018, 2017–2019, and 2018–2020 DVs are 66
ppb; and preliminary 2019–2021 DV is 66 ppb.
E:\FR\FM\22FEP2.SGM
22FEP2
9834
Federal Register / Vol. 87, No. 35 / Tuesday, February 22, 2022 / Proposed Rules
struggle with nonattainment or
maintenance in the future, and (2) that
Texas was linked to some set of these
receptors, even if the receptors and
linkages differed from one another in
their specifics (e.g., a different set of
receptors were identified to have
nonattainment or maintenance
problems, or Texas was linked to
different receptors in one modeling run
versus another). We think this common
result indicates that Texas’s emissions
were substantial enough to generate
linkages at Steps 1 and 2 to some set of
downwind receptors, under varying
assumptions and meteorological
conditions, even if the precise set of
linkages changed between modeling
runs.
In sum, the EPA’s more recent and
robust 2016 base year modeling
platform indicates that Texas is linked
to several receptors in the Midwest
Region as does the EPA’s earlier 2011
base year modeling. TCEQ’s 2012 base
case modeling showed linkages to states
in the west. As discussed, the EPA does
not find the additional weight of
evidence evaluations conducted by
TCEQ provide compelling reasons to
discount the impacts indicated in
Colorado and California by the TCEQ
modeling. In fact, we think TCEQ’s
modeling likely underestimates these
issues. We therefore propose that Texas
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
Texas failed to do so.
lotter on DSK11XQN23PROD with PROPOSALS2
5. Evaluation of Information Provided
by TCEQ 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. Texas
indicated that because a number of
counties in its state had been designated
nonattainment for the 2015 ozone
NAAQS, there could be attainment
demonstration and potential controls
contemplated in association with those
nonattainment designations.110
110 Pointing to anticipated upcoming emission
reductions, even if they were not included in the
analysis at Steps 1 and 2, is not sufficient as a Step
3 analysis, for the reasons discussed in Section
V.B.4 of this action. In this section, we explain that
to the extent such anticipated reductions are not
included in the SIP and rendered permanent and
VerDate Sep<11>2014
20:06 Feb 18, 2022
Jkt 256001
However, the State’s interstate transport
submission did not revise its SIP to
identify any specific emission
reductions, nor did it include a revision
to its SIP to ensure any such reductions
were permanent and enforceable. The
other control measures identified in
TCEQ’s submission are, as noted by
TCEQ, already adopted and
implemented measures and do not
contain an evaluation of additional
emission control opportunities (or
establish that no additional controls are
required). As a result, the EPA proposes
to disapprove TCEQ’s submittal on the
separate, additional basis that the Texas
has not included permanent and
enforceable emissions reductions in its
SIP as necessary to meet the obligations
of CAA section 110(a)(2)(d)(i)(I).
6. Conclusion
Based on the EPA’s evaluation of
TCEQ’s SIP submission, the EPA is
proposing to find that the Texas August
17, 2018, SIP submission pertaining to
interstate transport of air pollution 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
ozone NAAQS in any other state.
VI. Proposed Action
We are proposing to disapprove the
SIP submissions from Arkansas,
Louisiana, Oklahoma, and Texas
pertaining to interstate transport of air
pollution which will significantly
contribute to nonattainment or interfere
with maintenance of the 2015 ozone
NAAQS in other states. Under CAA
section 110(c)(1), the disapprovals
would establish a 2-year deadline for
the EPA to promulgate FIPs for these
states 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 ozone NAAQS in other states,
unless the EPA approves SIPs that meet
these requirements. Disapproval does
not start a mandatory sanctions clock for
Arkansas, Louisiana, Oklahoma, or
Texas.
enforceable, reliance on such anticipated reductions
is also insufficient at Step 4.
PO 00000
Frm 00038
Fmt 4701
Sfmt 4702
VII. 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
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 proposed action disapproving
the portion of Oklahoma’s SIP
submission addressing the State’s
interstate transport obligations under
CAA section 110(a)(2)(D)(i)(I) for the
2015 ozone NAAQS will apply to
certain areas of Indian country as
discussed in Section IV.C of this action,
and therefore, has tribal implications as
specified in E.O. 13175 (65 FR 67249,
November 9, 2000). However, this
proposed action will neither impose
substantial direct compliance costs on
federally recognized tribal governments,
nor preempt tribal law. This proposed
action will not impose substantial direct
compliance costs on federally
recognized tribal governments because
no actions will be required of tribal
governments. This proposed action will
E:\FR\FM\22FEP2.SGM
22FEP2
Federal Register / Vol. 87, No. 35 / Tuesday, February 22, 2022 / Proposed Rules
also not preempt tribal law as no
Oklahoma tribe implements a regulatory
program under the CAA, and thus does
not have applicable or related tribal
laws. Consistent with the EPA Policy on
Consultation and Coordination with
Indian Tribes (May 4, 2011), the EPA
will offer consultation to tribal
governments whose lands are located
within the exterior boundaries of the
State of Oklahoma that may be affected
by 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.
lotter on DSK11XQN23PROD with PROPOSALS2
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
VerDate Sep<11>2014
20:06 Feb 18, 2022
Jkt 256001
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).111
The EPA anticipates that this
proposed rulemaking, if finalized,
would be ‘‘nationally applicable’’
within the meaning of CAA section
307(b)(1) because it would take final
action on SIP submittals for the 2015
ozone NAAQS for four states, which are
located in three different Federal
judicial circuits. It would apply
uniform, nationwide analytical
methods, policy judgments, and
interpretation with respect to the same
CAA obligations, i.e., implementation of
interstate transport requirements under
CAA section 110(a)(2)(D)(i)(I) for the
2015 ozone NAAQS for states across the
country, and final action would be
based on this common core of
determinations, described in further
detail below.
If the EPA takes final action on this
proposed rulemaking[, in the
alternative,] 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
111 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 00039
Fmt 4701
Sfmt 9990
9835
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 interstate transport
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 the 4Step 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.112 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).113
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 1, 2022.
Earthea Nance,
Regional Administrator, Region 6.
[FR Doc. 2022–02961 Filed 2–18–22; 8:45 am]
BILLING CODE 6560–50–P
112 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.
113 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 the 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\22FEP2.SGM
22FEP2
]]>Agencies
[Federal Register Volume 87, Number 35 (Tuesday, February 22, 2022)]
[Proposed Rules]
[Pages 9798-9835]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2022-02961]
[[Page 9797]]
Vol. 87
Tuesday,
No. 35
February 22, 2022
Part II
Environmental Protection Agency
-----------------------------------------------------------------------
40 CFR Part 52
Air Plan Disapproval; Arkansas, Louisiana, Oklahoma, and Texas;
Interstate Transport of Air Pollution for the 2015 8-Hour Ozone
National Ambient Air Quality Standards; Proposed Rule
Federal Register / Vol. 87, No. 35 / Tuesday, February 22, 2022 /
Proposed Rules
[[Page 9798]]
-----------------------------------------------------------------------
ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 52
[EPA-R06-OAR-2021-0801, EPA-HQ-OAR-2021-0663; FRL-9338-01-R6]
Air Plan Disapproval; Arkansas, Louisiana, Oklahoma, and Texas;
Interstate Transport of Air Pollution for the 2015 8-Hour Ozone
National Ambient Air Quality Standards
AGENCY: Environmental Protection Agency (EPA).
ACTION: Proposed rule.
-----------------------------------------------------------------------
SUMMARY: 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 Arkansas,
Louisiana, Oklahoma and Texas regarding interstate transport for the
2015 8-hour ozone national ambient air quality standard (NAAQS). This
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. The ``good neighbor'' or ``interstate
transport'' 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-R06-OAR-
2021-0801, by any of the following methods: Federal eRulemaking Portal
at https://www.regulations.gov following the online instructions for
submitting comments or via email to [email protected]. Include
Docket ID No. EPA-R06-OAR-2021-0801 in the subject line of the message.
Instructions: All comments submitted 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 the EPA
Docket Center services and the current status, please visit us online
at https://www.epa.gov/dockets.
FOR FURTHER INFORMATION CONTACT: Sherry Fuerst, EPA Region 6 Office,
AR-SI, 214-665-6454, [email protected]. We encourage the public to
submit comments via https://www.regulations.gov, as there will be a
delay in processing mail and no courier or hand deliveries will be
accepted. Please call or email the contact above if you need
alternative access to material indexed but not provided in the docket.
SUPPLEMENTARY INFORMATION: Public Participation: Submit your comments,
identified by Docket ID No. EPA-R06-OAR-2021-0801, 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 the 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-R06-OAR-2021-0801
and EPA-HQ-OAR-2021-0663. Docket No. EPA-R06-OAR-2021-0801 contains
information specific to Arkansas, Louisiana, Oklahoma, and Texas,
including the notice of proposed rulemaking, submittals from the
states, and the EPA Region 6 2015 8-Hour Ozone Transport SIP Proposal
Technical Support Document (EPA Region 6 TSD). 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,
including Preparation of Emissions Inventories for the 2016v2 North
American Emissions Modeling Platform, and Air Quality Modeling TSD for
2015 ozone NAAQS Transport SIP Proposed Actions. All comments regarding
information in either of these dockets are to be made in Docket No.
EPA-R06-OAR-2021-0801. For additional submission methods, please
contact Sherry Fuerst, 214-665-6454, [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 dockets for this action, Docket No. EPA-R06-OAR-
2021-0801 and EPA-HQ-OAR-2021-0663, are available electronically at
https://www.regulations.gov. While all documents in the docket are
listed in the index, some information may not be publicly available due
to docket file size restrictions or content (e.g., CBI).
Throughout this document, ``we,'' ``us,'' and ``our'' means the
EPA.
Table of Contents
I. Background
A. Description of Statutory Background
B. Description of the EPA's 4-Step Interstate Transport
Regulatory Process
C. Background on the EPA's Ozone Transport Modeling Information
D. The EPA's Approach to Evaluating Interstate Transport SIPs
for the 2015 Ozone NAAQS
1. Selection of Analytic Year
2. Step 1 of the 4-Step Interstate Transport Framework
3. Step 2 of the 4-Step Interstate Transport Framework
[[Page 9799]]
4. Step 3 of the 4-Step Interstate Transport Framework
5. Step 4 of the 4-Step Interstate Transport Framework
II. Arkansas SIP Submission Addressing Interstate Transport of Air
Pollution for the 2015 Ozone NAAQS and the EPA Evaluation of the SIP
Submission
A. Summary of ADEQ SIP Submission Addressing Interstate
Transport of Air Pollution for the 2015 Ozone NAAQS
B. EPA Evaluation of the ADEQ SIP Submission
1. Evaluation of Information Provided by ADEQ Regarding Step 1
2. Evaluation of Information Provided by ADEQ Regarding Step 2
3. Results of the EPA's Step 1 and Step 2 Modeling and Findings
for Arkansas
4. Evaluation of Information Provided by ADEQ Regarding Step 3
5. Evaluation of Information Provided by ADEQ Regarding Step 4
6. Conclusion
III. Louisiana SIP Submission Addressing Interstate Transport of Air
Pollution for the 2015 Ozone NAAQS and the EPA Evaluation of the SIP
Submission
A. Summary of LDEQ SIP Submission Addressing Interstate
Transport of Air Pollution for the 2015 Ozone NAAQS
B. EPA Evaluation of the LDEQ SIP Submission
1. Evaluation of Information Provided by LDEQ Regarding Steps 1
and 2
2. Results of the EPA's Step 1 and Step 2 Modeling and Findings
for Louisiana
3. Evaluation of Information Provided by LDEQ Regarding Step 3
4. Evaluation of Information Provided by LDEQ Regarding Step 4
5. Conclusion
IV. Oklahoma SIP Submission Addressing Interstate Transport of Air
Pollution for the 2015 Ozone NAAQS and the EPA Evaluation of the SIP
Submission
A. Summary of ODEQ SIP Submission Addressing Interstate
Transport of Air Pollution for the 2015 Ozone NAAQS
B. EPA Evaluation of the ODEQ SIP Submission
1. Evaluation of Information Provided by ODEQ Regarding Steps 1
and 2
2. Results of the EPA's Step 1 and Step 2 Modeling and Findings
for Oklahoma
3. Evaluation of Information Provided by ODEQ Regarding Step 3
4. Evaluation of Information Provided by ODEQ Regarding Step 4
5. Conclusion
C. Impact on Areas of Indian Country
V. Texas SIP Submission Addressing Interstate Transport of Air
Pollution for the 2015 Ozone NAAQS and the EPA Evaluation of the SIP
Submission
A. Summary of TCEQ SIP Submission Addressing Interstate
Transport of Air Pollution for the 2015 Ozone NAAQS
B. EPA Evaluation of the TCEQ SIP Submission
1. Evaluation of Information Provided by TCEQ Regarding Step 1
i. Evaluation of TCEQ's Methodology for Identifying Maintenance
Receptors
ii. Evaluation of the TCEQ Modeling
2. Evaluation of Information Provided by TCEQ Regarding Step 2
3. Results of the EPA's Step 1 and Step 2 Modeling and Findings
for Texas
4. Evaluation of Information Provided by TCEQ Regarding Step 3
5. Evaluation of Information Provided by TCEQ Regarding Step 4
6. Conclusion
VI. Proposed Action
VII. Statutory and Executive Order Reviews
I. Background
A. Description of Statutory Background
On October 1, 2015, the EPA promulgated a revision to the 2015 8-
hour ozone NAAQS (2015 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 requirements, often
referred to as ``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\
---------------------------------------------------------------------------
\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).
---------------------------------------------------------------------------
B. Description of the EPA's 4-Step Interstate Transport Regulatory
Process
The EPA is using the 4-Step interstate transport framework (or 4-
Step framework) described in detail below to evaluate states' SIP
submittals addressing the interstate transport provision for the 2015
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\
---------------------------------------------------------------------------
\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\ See ``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).
---------------------------------------------------------------------------
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 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.
---------------------------------------------------------------------------
\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).
---------------------------------------------------------------------------
[[Page 9800]]
C. Background on the EPA's Ozone Transport Modeling Information
In general, the EPA has performed nationwide air quality modeling
to project ozone design values (DVs) \8\ which are used in combination
with measured data to identify nonattainment and maintenance receptors.
To quantify the contribution of emissions from specific upwind states
on 2023 ozone DVs for the identified downwind nonattainment and
maintenance receptors, the EPA performed nationwide, state-level ozone
source apportionment modeling for 2023. The source apportionment
modeling provided contributions to ozone at receptors from precursor
emissions of anthropogenic nitrogen oxides (NOX) and
volatile organic compounds (VOCs) in individual upwind states.
---------------------------------------------------------------------------
\8\ A design value is a statistic that describes the air quality
status of a given location relative to the level of the NAAQS.
Design values are typically used to designate and classify
nonattainment areas, as well as to assess progress towards meeting
the NAAQS. See https://www.epa.gov/air-trends/air-quality-design-values#report.
---------------------------------------------------------------------------
The EPA has released several documents containing projected ozone
design values, contributions, and information relevant to evaluating
interstate transport with respect to the 2015 ozone NAAQS. First, on
January 6, 2017, the EPA published a notice of data availability (NODA)
in which we requested comment on preliminary interstate ozone transport
data including projected ozone DVs and interstate contributions for
2023 using a 2011 base year platform.\9\ 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 NAAQS.\10\ 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.\11\ On March 27, 2018, we issued a memorandum
(March 2018 memorandum) noting that the same 2023 modeling data
released in the October 2017 memorandum could also be useful for
identifying potential downwind air quality problems with respect to the
2015 ozone NAAQS at Step 1 of the 4-Step framework.\12\ The March 2018
memorandum also included the then newly available contribution modeling
data to assist states in evaluating their impact on potential downwind
air quality problems for the 2015 ozone NAAQS under Step 2 of the 4-
Step framework.\13\ The EPA subsequently issued two more memoranda in
August and October 2018, providing additional information to states
developing interstate transport SIP submissions for the 2015 ozone
NAAQS concerning, respectively, potential contribution thresholds that
may be appropriate to apply in Step 2 of the 4-Step interstate
transport framework, and considerations for identifying downwind areas
that may have problems maintaining the standard at Step 1 of the 4-Step
interstate transport framework.\14\
---------------------------------------------------------------------------
\9\ 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).
\10\ 82 FR at 1735.
\11\ See EPA memorandum, ``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, (``October 2017
memorandum'') available in Docket ID No. EPA-HQ-OAR-2021-0663 or at
https://www.epa.gov/interstate-air-pollution-transport/interstate-air-pollution-transport-memos-and-notices.
\12\ See EPA memorandum, ``Information on the Interstate
Transport State Implementation Plan Submissions for the 2015 Ozone
National Ambient Air Quality Standards under Clean Air Act section
110(a)(2)(D)(i)(I)'', March 27, 2018, (``March 2018 memorandum'')
available in Docket ID No. EPA-HQ-OAR-2021-0663 or at https://www.epa.gov/interstate-air-pollution-transport/interstate-air-pollution-transport-memos-and-notices.
\13\ 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 interstate transport provision. Any such
determination would be made through notice-and-comment rulemaking.''
\14\ See EPA memorandums, ``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 (``October 2018 memorandum''), available in Docket ID No. EPA-
HQ-OAR-2021-0663 or at https://www.epa.gov/airmarkets/memo-and-supplemental-information-regarding-interstate-transport-sips-2015-ozone-naaqs.
---------------------------------------------------------------------------
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.\15\ 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 DVs 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.\16\ See 85 FR 68964, 68981. Although the Revised CSAPR Update
addressed transport for the 2008 ozone NAAQS, the projected DVs and
contributions from the 2016v1 platform are also useful for identifying
downwind ozone problems and linkages with respect to the 2015 ozone
NAAQS.\17\
---------------------------------------------------------------------------
\15\ The results of this modeling, as well as the underlying
modeling files, are included in Docket ID No. EPA-HQ-OAR-2021-0663.
\16\ See 85 FR 68964, 68981 (Oct. 30, 2020).
\17\ See the Air Quality Modeling Technical Support Document for
the Final Revised Cross-State Air Pollution Rule Update, available
in Docket ID No. EPA-HQ-OAR-2021-0063 for this action.
---------------------------------------------------------------------------
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 \18\ 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
Technical Support Document (TSD) Preparation of Emissions Inventories
for the 2016v2 North American Emissions Modeling Platform, which is
included in Docket ID No. EPA-HQ-OAR-2021-0663. The EPA performed air
quality modeling of the 2016v2 emissions using the most recent publicly
released version of the Comprehensive Air-quality Model with extensions
(CAMx) photochemical modeling, version 7.10.\19\ The EPA now proposes
to rely on the air quality modeling performed using CAMx, version 7.10,
and the newly available 2016v2 emissions platform in evaluating states'
submissions with respect to Steps
[[Page 9801]]
1 and 2 of the 4-Step framework and generally referenced within this
action as 2016v2 modeling for 2023. By using the updated modeling
results, the EPA is using the most current and technically appropriate
information for this proposed rulemaking. Sections II-V of this action
and the Air Quality Modeling TSD for 2015 ozone NAAQS Transport SIP
Proposed Actions, included in Docket ID No. EPA-HQ-OAR-2021-0663 for
this proposal, contain additional detail on the EPA's 2016v2 modeling.
In this action, the EPA is inviting public comment on this updated 2023
modeling, which uses a 2016v2 emissions platform. Per the instructions
in the Supplementary Information section above, all public comments,
including comments on the EPA's air quality modeling should be
submitted in the Regional docket for this action, Docket ID No. EPA-
R06-OAR-2021-0801. Comments are not being accepted in Docket No. EPA-
HQ-OAR-2021-0663.
---------------------------------------------------------------------------
\18\ 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.
\19\ Ramboll Environment and Health, January 2021, www.camx.com.
---------------------------------------------------------------------------
States may have chosen to rely on the results of 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 Sections II-V of this
action, we evaluate how the states used air quality modeling
information in their submissions.
D. The EPA's Approach to Evaluating Interstate Transport SIPs for the
2015 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 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 1998 NOX SIP
Call \20\ 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).
---------------------------------------------------------------------------
\20\ See 63 FR 57356. The NOX SIP Call required 22
eastern states and the District of Columbia to submit state
implementation plans (SIPs) that set statewide ozone season NOx
budgets which would reduce emissions of NOX.
---------------------------------------------------------------------------
In the March, August, and October 2018 memoranda, the EPA
recognized that states may be able to establish alternative approaches
to addressing their interstate transport obligations for the 2015 ozone
NAAQS that vary from a nationally uniform framework. The EPA emphasized
in these memoranda, however, that such alternative approaches must be
technically justified and appropriate in light of the facts and
circumstances of each particular state's 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.\21\ However, the EPA made clear in
Attachment A that the list of ideas were not suggestions endorsed by
the Agency but rather ``comments provided in various forums'' on which
the EPA sought ``feedback from interested stakeholders.'' \22\ 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.'' \23\ 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 review the technical and legal justifications
for doing so.
---------------------------------------------------------------------------
\21\ March 2018 memorandum, Attachment A.
\22\ Id. at A-1.
\23\ Id.
---------------------------------------------------------------------------
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 analysis.
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).\24\ 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.
---------------------------------------------------------------------------
\24\ 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).
---------------------------------------------------------------------------
On May 19, 2020, the D.C. Circuit issued a decision in Maryland v.
EPA that cited the Wisconsin decision in holding that the EPA must
assess the impact of interstate transport on air quality at the next
downwind attainment date, including Marginal area attainment dates, in
evaluating the basis for the EPA's denial of a petition under CAA
section 126(b). Maryland v. EPA, 958 F.3d 1185, 1203-04 (D.C. Cir.
2020). The court noted that ``section 126(b) incorporates the Good
Neighbor Provision,'' and, therefore, ``EPA must find a violation [of
section 126] if an upwind source will significantly contribute to
downwind nonattainment at the next downwind attainment deadline.
Therefore, the agency must evaluate downwind air quality at that
deadline, not at some later date.'' Id. at 1204 (emphasis added). The
EPA interprets the court's holding in Maryland as requiring the states
and the Agency, under the interstate transport provision, to assess
downwind air quality as expeditiously as practicable and no later than
the next applicable
[[Page 9802]]
attainment date,\25\ which is now the Moderate area attainment date
under CAA section 181 for ozone nonattainment. The Moderate area
attainment date for the 2015 ozone NAAQS is August 3, 2024.\26\ The EPA
believes that 2023 is now the appropriate year for analysis of
interstate transport obligations for the 2015 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 ozone NAAQS.
---------------------------------------------------------------------------
\25\ 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 4-Step 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.
\26\ 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).
---------------------------------------------------------------------------
The EPA recognizes that the attainment date for nonattainment areas
classified as Marginal for the 2015 ozone NAAQS was August 3, 2021.
Under the Maryland holding, any necessary emissions reductions to
satisfy interstate transport obligations should have been implemented
by no later than this date. At the time of the statutory deadline to
submit interstate transport SIPs (October 1, 2018), many states relied
upon the EPA modeling of the year 2023, and no state provided an
alternative analysis using a 2021 analytic year (or the prior 2020
ozone season). However, the EPA must act on SIP submittals using the
information available at the time it takes such action. In this
circumstance, the EPA does not believe it would be appropriate to
evaluate states' obligations under CAA section 110(a)(2)(D)(i)(I) as of
an attainment date that is wholly in the past, because the Agency
interprets the interstate transport provision as forward looking. See
86 FR at 23074; see also Wisconsin, 938 F.3d at 322. Consequently, in
this proposal the EPA proposes to 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 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
framework. For sites that are identified as a nonattainment or
maintenance receptor in 2023, we proceed to the next step of our 4-Step
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.\27\
---------------------------------------------------------------------------
\27\ 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 DVs in 2023 that exceed the NAAQS and that
are also measuring nonattainment based on the most recent monitored
DVs. 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).\28\
---------------------------------------------------------------------------
\28\ 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).\29\ 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 DV
at each receptor based on a projection of the maximum measured DV over
the relevant period. The EPA interprets the projected maximum future DV
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 DV 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 DV is used to identify upwind emissions
that, under those circumstances, could interfere with the downwind
area's ability to maintain the NAAQS.
---------------------------------------------------------------------------
\29\ 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 DVs above the level of the
applicable NAAQS, but that are not currently measuring nonattainment
based on the most recent official DVs. In addition, those monitoring
sites with projected average DVs below the NAAQS, but with projected
maximum DVs above the NAAQS are also identified as ``maintenance only''
receptors, even if they are currently measuring nonattainment based on
the most recent official DVs.
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 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
[[Page 9803]]
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 of controls as part of a
multifactor 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 continue 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
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. For ozone, as the EPA found in the Clean Air Interstate Rule
(CAIR), CSAPR, and CSAPR Update, a portion of the nonattainment problem
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 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 analysis 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 preparing a
multifactor assessment that evaluates additional available control
opportunities. 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.\30\
---------------------------------------------------------------------------
\30\ As examples of general approaches for how such an analysis
could be conducted for their sources, states could look to the CSAPR
Update, 81 FR 74504, 74539-51; CSAPR, 76 FR 48208, 48246-63; CAIR,
70 FR 25162, 25195-229; or the NOX SIP Call, 63 FR 57356,
57399-405. See also Revised CSAPR Update, 86 FR 23054, 23086-23116.
Consistently across these rulemakings, the EPA has developed
emissions inventories, analyzed different levels of control
stringency at different cost thresholds, and assessed resulting
downwind air quality improvements.
---------------------------------------------------------------------------
5. Step 4 of the 4-Step Interstate Transport Framework
In Step 4, states (or the EPA) develop permanent and federally
enforceable control strategies to achieve the emissions reductions
determined to be necessary in Step 3 to eliminate significant
contribution to nonattainment or interference with maintenance of the
NAAQS. For a state linked in Steps 1 and 2 to rely on an emissions
control measure in 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 section 110(a)(2)(A); Committee for a Better Arvin v. U.S.
E.P.A., 786 F.3d 1169, 1175-76 (9th Cir. 2015) (holding that measures
relied on by state to meet CAA requirements must be included in the
SIP).
II. Arkansas SIP Submission Addressing Interstate Transport of Air
Pollution for the 2015 Ozone NAAQS and the EPA Evaluation of the SIP
Submission
A. Summary of ADEQ SIP Submission Addressing Interstate Transport of
Air Pollution for the 2015 Ozone NAAQS
On October 10, 2019, the Arkansas Division of Environmental Quality
(ADEQ) of the Arkansas Department of Energy and Environment made a SIP
submission addressing interstate transport of air pollution for the
2015 ozone NAAQS. The ADEQ SIP submission provided an analysis of
Arkansas's air emissions impact to downwind states using the EPA's 4-
Step framework and an analytic year of 2023 and concluded that the
State's air emissions will not contribute significantly to
nonattainment or interfere with maintenance of the 2015 ozone NAAQS in
other states.
To identify downwind monitors projected to be in nonattainment and/
or have maintenance issues in 2023 (Step 1), ADEQ relied on the EPA's
interstate transport modeling results that are included as an
attachment to the March 2018 memorandum. The EPA modeling results
included with the March 2018 memorandum provide: (1) Projected
[[Page 9804]]
average DV and maximum DV for the future year 2023 (fy 2023) for ozone
monitors projected to be potential nonattainment or maintenance
receptors in the 48 contiguous States and (2) the expected contribution
of State emissions to the projected ozone concentrations at each ozone
monitor.
At Step 2, ADEQ identified those states to which Arkansas
contributes emissions and then applied a 1 ppb contribution threshold
to determine projected nonattainment and/or maintenance receptors in
other states that might be significantly impacted by emissions from
Arkansas. ADEQ provided three rationales as a basis to support their
decision to rely on a 1 ppb contribution threshold. First, ADEQ cited
to the August 2018 memorandum \31\ that compares the collective
contribution captured by three different contribution thresholds: 1
Percent of the NAAQS, 1 ppb, and 2 ppb. ADEQ summarized the August 2018
memorandum and concluded that the 1 percent and 1 ppb contribution
thresholds are generally comparable. Second, ADEQ referenced an April
2018 memorandum \32\ in which the EPA examined the use of a significant
impact level (SIL) value of 1 ppb for determining whether a proposed
prevention of significant deterioration (PSD) source causes or
contributes to a violation of the corresponding 2015 ozone NAAQS.
Despite recognizing that a contribution threshold is not the same as a
significance level, ADEQ claimed that a contribution threshold and
significance level are sufficiently analogous to support the use of a 1
ppb contribution threshold. The final rationale ADEQ provided was based
on the consistency with the reported precision of Federal reference
monitors for ozone and the rounding requirements found in 40 CFR part
50, Appendix U, Interpretation of the Primary and Secondary National
Ambient Air Quality Standards for Ozone. ADEQ noted that the 1 percent
contribution threshold of 0.7 ppb is lower than the manufacturer's
reported precision of Federal reference monitors for ozone and that the
requirements found in Appendix U truncates monitor values of 0.7 ppb to
0 ppb.
---------------------------------------------------------------------------
\31\ ``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, available in Docket ID No.
EPA-HQ-OAR-2021-0663 or at https://www.epa.gov/airmarkets/memo-and-supplemental-information-regarding-interstate-transport-sips-2015-ozone-naaqs.
\32\ See EPA memorandum from Peter Tsirigotis, Director of the
Office of Air Quality planning and Standards, April 17, 2018,
``Guidance on Significant Impact Levels for Ozone and Fine Particles
in the Prevention of Significant Deterioration Permitting Program''
(``SILs Guidance'' or ``April 2018 memorandum''), available at:
https://www.epa.gov/sites/default/files/2018-04/documents/sils_policy_guidance_document_final_signed_4-17-18.pdf.
---------------------------------------------------------------------------
As stated previously, ADEQ identified all potential nonattainment
and maintenance receptors for fy 2023 showing a contribution of
emissions from Arkansas.\33\ These receptors are included in Table AR-
1.
---------------------------------------------------------------------------
\33\ Table AR-1 lists all sites that the EPA projected to have a
fy 2023 average DV or fy 2023 maximum DV greater than 70.9 ppb in
our March 2018 memorandum. As Arkansas stated in the SIP submission,
the EPA considers sites matching these criteria to be projected
nonattainment areas and projected maintenance areas, respectively.
ADEQ ranked these sites by Arkansas's potential contribution, which
the EPA determined based on the daily eight-hour average
contributions on the top ten concentration days in 2023.
Table AR-1--Projected Nonattainment and Maintenance Receptors Identified by Arkansas Based on the EPA's March
2018 Memorandum
----------------------------------------------------------------------------------------------------------------
Arkansas
Receptor (site ID, county, state) 2023 average 2023 maximum contribution
DV (ppb) DV (ppb) (ppb)
----------------------------------------------------------------------------------------------------------------
260050003, Allegan, MI.......................................... 69 71.7 1.64
482011039, Harris, TX........................................... 71.8 73.5 0.99
480391004, Brazoria, TX......................................... 74 74.9 0.90
484392003, Tarrant, TX.......................................... 72.5 74.8 0.78
481210034, Denton, TX........................................... 69.7 72 0.58
482011034, Harris, TX........................................... 70.8 71.6 0.54
551170006, Sheboygan, WI........................................ 72.8 75.1 0.51
550790085, Milwaukee, WI........................................ 71.2 73 0.40
482010024, Harris, TX........................................... 70.4 72.8 0.29
261630019, Wayne, MI............................................ 69 71 0.27
240251001, Harford, MD.......................................... 70.9 73.3 0.17
90019003, Fairfield, CT......................................... 73 75.9 0.13
90013007, Fairfield, CT......................................... 71 75 0.13
361030002, Suffolk, NY.......................................... 74 75.5 0.12
360810124, Queens, NY........................................... 70.2 72 0.09
90099002, New Haven, CT......................................... 69.9 72.6 0.08
90010017, Fairfield, CT......................................... 68.9 71.2 0.07
80590006, Jefferson, CO......................................... 71.3 73.7 0.03
80590011, Jefferson, CO......................................... 70.9 73.9 0.02
81230009, Weld, CO.............................................. 70.2 71.4 0.02
80350004, Douglas, CO........................................... 71.1 73.2 0.01
----------------------------------------------------------------------------------------------------------------
Based on a 1 ppb contribution threshold, ADEQ identified only one
fy 2023 projected maintenance receptor, Allegan County, MI, and no fy
2023 projected nonattainment receptors linked to Arkansas. ADEQ also
cited other modeling performed by TCEQ and Midwest Ozone Group, which
showed that when different modeling protocols were employed, future
year DV projections and contributions could differ considerably. ADEQ
therefore elected to consider other evidence regarding its linkage to
air quality in Allegan County, MI. Specifically, ADEQ analyzed back
trajectory information to infer that there is no consistent or
persistent relationship between elevated ozone days in Allegan County,
MI and air traveling through Arkansas. ADEQ assessed wind patterns on
elevated ozone days--days with a maximum daily average 8-hour ozone
(MDA8) greater than 70.9 ppb in Allegan County,
[[Page 9805]]
MI. ADEQ used the National Oceanic and Atmospheric Administration
(NOAA) HYbrid Single Particle Lagrangian Integrated Trajectory
(HYSPLIT) \34\ model to evaluate wind back trajectories from over a 10-
year period (2008-2017).\35\ Over the course of the 10-year period,
ADEQ identified 95 elevated ozone days (MDA8 > 70.9 ppb) for the
Allegan County, MI monitor.\36\ Next, ADEQ identified the maximum ozone
value within these elevated ozone days.\37\ Using HYSPLIT, ADEQ ran 72-
hour back trajectories using the hour of the maximum ozone value for
each elevated day as the back trajectory start time. To consider the
effects of vertical variations in wind flows on transport patterns,
ADEQ used the following starting heights above ground level: 100m,
500m, 1000m, and 1500m. ADEQ obtained 40 km grid meteorological data
for the back trajectory analysis using Eta Data Assimilation System
(EDAS) data.\38\ In total, ADEQ ran 152 back trajectories for each
mixing height.\39\ ADEQ filtered the back trajectories to determine
whether further analysis is warranted using two criteria. First, ADEQ
filtered out back trajectories that had a starting hour mixing height
below the back trajectory start height because ADEQ asserted these air
parcels would not have reached ambient air \40\ at the Allegan County,
MI monitor site. Second, ADEQ filtered out any back trajectory that did
not have a path through any portion of Arkansas. After ADEQ applied
their filter criteria, 41 out of 608 back trajectories (6.74%) remained
from 22 out of the 95 elevated ozone days (23%) examined. Of the 10
years examined, ADEQ also found that air passing through Arkansas only
reached Allegan County, MI on four or more days in one year: 2012.\41\
For 2012, HYSPLIT analyses indicated 14 Arkansas-Allegan County, MI
linked back trajectories for 7 days in total in 2012, whereas for 2011,
2013, 2014, and 2016 the HYSPLIT analyses indicated three, two, zero
and one days with Arkansas-Allegan County, MI linked back trajectories,
respectively. For the 10 years ADEQ's performed HYSPLITs, ADEQ's
HYSPLIT analysis indicated on average 2.2 days per year had
trajectories with Arkansas-Allegan County, MI linked back trajectories.
ADEQ also noted that these trajectories passed through other states and
through Metropolitan Statistical Areas (MSAs) \42\ both before and
after traversing through Arkansas. Specifically, ADEQ stated that 37
trajectories passed through the Chicago-Naperville-Elgin, IL-IN-WI MSA
prior to reaching Allegan County, MI. Based on these results, ADEQ
concluded that other states and MSAs were more likely to have
influenced ozone concentrations at the Allegan County, MI monitor on
the days with back trajectories linked to Arkansas.
---------------------------------------------------------------------------
\34\ HYbrid Single-Particle Lagrangian Integrated Trajectory
(HYSPLIT) model is a complete system for computing both simple air
parcel trajectories and complex dispersion and deposition
simulations. The model is designed to support a wide range of
simulations related to the atmospheric transport and dispersion of
pollutants and hazardous materials to the Earth's surface.
\35\ ADEQ analyzed ten years of HYSPLIT back trajectories to
examine potential relationships between elevated ozone days at the
Allegan County, MI monitor and emissions from Arkansas. In the SIP
submission ADEQ stated their rationale for looking at an extended
period of time is to gain a more complete picture of how Arkansas's
emissions might contribute to elevated ozone in Allegan County, MI,
rather than relying entirely on the EPA's modeling simulation, which
is based on a single base year.
\36\ See the AirNow-Tech website at https://www.airnowtech.org/.
AirNow-Tech is a website for air quality data management analysis,
and decision support used by the Federal, State, Tribal, and local
air quality organizations.
\37\ If the same maximum eight-hour value occurred multiple
times a day, ADEQ evaluated all incidences of the value for that
day.
\38\ EDAS is an intermittent data assimilation system that uses
successive three-hour model forecasts to generate gridded
meteorological fields that reflect observations covering the
continental United States. EDAS is accessible at https://ready.arl.noaa.gov/edas40.php.
\39\ Mixing heights (m), defined as the height above ground
level of the layer adjacent to the ground over which an emitted or
entrained inert non-buoyant tracer will be mixed by turbulence.
\40\ Ambient air is the ``portion of the atmosphere, external to
buildings, to which the general public has access.'' 40 CFR 50.1(e).
\41\ The number of days in a given year and the number of
consecutive years is of particular relevance for the ozone NAAQS,
which is calculated based the annual fourth-highest daily maximum
eight-hour concentration averaged over three consecutive years.
\42\ MSA is defined as a geographic region with a high
population density at its core and close economic ties throughout
the area.
---------------------------------------------------------------------------
In Step 3, ADEQ also considered air quality trends in Allegan
County, MI, emission trends in other upwind states, relative
contribution from other upwind states, and cost factors. ADEQ presented
that ozone DVs in Allegan County, MI fluctuated over the 2008-2017
period with higher concentration occurring from 2012 through 2014 but
declining since 2014. ADEQ also mentioned that despite the most recent
2017 DV for the Allegan County monitor continuing to show an exceedance
of the 2015 ozone NAAQS, the EPA-projected 2023 ozone average DV at the
Allegan County, MI monitor, based on data provided in the March 2018
memorandum, is 69.0 ppb, which would be in attainment of the 2015 ozone
NAAQS in 2023.
Next, ADEQ included an evaluation of the relative contribution and
the emission trends from the eight states \43\ with contributions
greater than 1 ppb to the Allegan County, MI receptor. The emission
trends evaluation examined ozone precursors, nitrogen oxides
(NOX) and volatile organic compounds (VOC), from 2011 to
2017 and the model projected fy 2023 emissions level. ADEQ noted that
the two states with the highest contributions to Allegan County, MI--
Illinois and Indiana--have both experienced year-over-year decreases in
NOX emissions in excess of 20,000 tons of NOX
reduced per year. Arkansas had also experienced decreases in
NOX emissions each evaluated year and emitted less
NOX than any other of the potentially linked states. In
addition, ADEQ referenced the EPA projections showing that most
potentially linked states will continue to realize reductions in
NOX, as well as VOCs, through 2023. ADEQ confirmed that
based on this analysis, the overall general trends of NOX
and VOC emissions are declining from Arkansas and the other linked
states. The continuation of trends in the emissions reductions
observed, particularly from Illinois and Indiana, are anticipated by
ADEQ to result in air quality improvements in Allegan County, MI.
---------------------------------------------------------------------------
\43\ The eight linked states include Illinois, 42%; Indiana,
15%; Michigan, 7%; Missouri, 6%; Texas, 5%; Wisconsin, 4%; Oklahoma,
3% and Arkansas, 4%. The remaining contribution is labeled at
``Other''. The linkages are based on the EPA's modeling results that
are attached to the March 2018 memorandum.
---------------------------------------------------------------------------
In terms of cost analysis, ADEQ focused only on the cost of
NOX controls at electric generating units (EGUs) in the
State because EGUs are the largest source of NOX emissions
that ADEQ regulates. In its analysis, ADEQ found that the costs to
install additional NOX controls (selective catalytic
reduction, SCR and selective noncatalytic reduction, SNCR) at EGUs
exceed the EPA's cost thresholds used for the CSAPR and CSAPR Update
rules.\44\ Based on ADEQ's evaluation of the evidence, ADEQ concluded
that no additional controls beyond pre-existing
[[Page 9806]]
state and Federal regulations were warranted for Arkansas sources to
satisfy interstate transport obligations for the 2015 ozone NAAQS.
---------------------------------------------------------------------------
\44\ The EPA's Revised CSAPR Update, 86 FR 23054 (April 20,
2021), states ``. . . EPA adjusted its representative cost for
optimizing existing SNCR control to $1,800 per ton in response to
comments received on the proposed rule . . . EPA views $1,600 per
ton for optimization of existing SCR control and installation of
state-of-the are NOX combustion controls and $1,800 per
ton for optimization of existing SNCRs as comparable for policy
purposes.'' ADEQ's screening analysis using the EPA tools
(referencing the EPA's Air Pollution Control Cost Estimation
Spreadsheet for SCR) shows that cost-effectiveness values for ozone-
season operation of SCR and SNCR are: $12,605-$31,580/ton for SCR
and $4,221-$45,581 for SNCR. ADEQ notes that any costs imposed to
install controls at the examined EGUs would be passed on to Arkansas
ratepayers.
---------------------------------------------------------------------------
Based on the determinations made by ADEQ at Steps 1 through 3, ADEQ
did not include any new control measures in the SIP submission to
reduce ozone precursor emissions as part of a Step 4 analysis.
B. EPA Evaluation of the ADEQ SIP Submission
The EPA is proposing to find that ADEQ's October 10, 2019, SIP
submission does not meet the State's obligations with respect to
prohibiting emissions that contribute significantly to nonattainment or
interfere with maintenance of the 2015 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 ADEQ's SIP submission.
1. Evaluation of Information Provided by ADEQ Regarding Step 1
At Step 1 of the 4-Step framework, ADEQ relied on the EPA modeling
released in the March 2018 memorandum to identify nonattainment and
maintenance receptors in 2023. As described in Section I of this
action, the EPA has recently performed updated modeling using the
2016v2 platform to evaluate interstate transport of ozone for a fy
2023.\45\ The EPA proposes to primarily rely on the EPA's modeling
using the 2016v2 platform (EPA 2016v2 modeling), to identify projected
nonattainment and maintenance receptors in fy 2023. Updating the base
period from 2011 (base period used in data included in the March 2018
memorandum) to a more recent year (2016) allows for better projections
of which monitors will have problems attaining and/or maintaining the
2015 ozone NAAQS and factors in more recent base year DVs. The EPA
notes that with a switch from 2011 base period meteorology to 2016 base
period meteorology, it is normal and expected that the potential
downwind nonattainment or maintenance receptors would change due to the
different weather patterns that occurred in the different base periods,
which impacts both the transport of pollutants from upwind states and
what receptors have higher monitored values within nonattainment/
maintenance regions.\46\ Modeling using both the 2011 and 2016 based
years consistently project that certain areas will have problems
attaining and/or maintaining the 2015 ozone NAAQS including receptors
in Texas.
---------------------------------------------------------------------------
\45\ Per the instructions in the Supplementary Information
section above, all public comments, including comments on the EPA's
air quality modeling should be submitted in the Regional docket for
this action, Docket ID No. EPA-R06-OAR-2021-0801. Comments are not
being accepted in Docket No. EPA-HQ-OAR-2021-0663.
\46\ We note that ADEQ identified additional modeling performed
by TCEQ and Midwest Ozone Group, but simply concluded that different
modeling can lead to differences in DV projections and ozone
contributions of these two alternative modeling analyses, only
TCEQ's modeling using a 2012 base year identified receptors in Texas
that projected different DVs for the Texas receptors identified in
the EPA's 2011 base year. We discuss the EPA's review of the TCEQ's
modeling elsewhere in this action and the Technical Support Document
for this action ``EPA Region 6 2015 8-Hour Ozone Transport SIP
Proposal Technical Support Document'' (EPA Region 6 2015 Ozone
Transport SIP TSD.pdf) included in the Regional docket for this
action (Docket ID No. EPA-R06-OAR-2021-0801), but we do conclude
that TCEQ and recent monitoring data indicate that there are
problematic receptors that are expected to be either nonattainment
or maintenance receptors in 2023 including the Texas receptors that
the EPA identified in our March 2018 memorandum with Arkansas
linkages.
---------------------------------------------------------------------------
2. Evaluation of Information Provided by ADEQ Regarding Step 2
As noted earlier, ADEQ utilized a 1 ppb threshold at Step 2 to
identify whether the State was ``linked'' to a projected downwind
nonattainment or maintenance receptor. ADEQ identified linkages for
Arkansas to one 2023 projected maintenance receptor, Allegan County,
MI, and no 2023 projected nonattainment receptors.
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 as an alternative to a 1 percent threshold, at
Step 2 of the 4-Step interstate transport framework, for the purposes
of identifying linkages to downwind receptors. However, the EPA's
August 2018 memorandum provided that whether or not a 1 ppb threshold
is appropriate must be based on an evaluation of state-specific
circumstances, and no such evaluation was included in the state's
submittal. Instead, ADEQ cited to the EPA's SILs Guidance as a basis to
support the use of a 1 ppb threshold; however, ADEQ did not explain the
relevance of the SILs Guidance to ADEQ's statutory obligation under the
interstate transport provision. The SILs Guidance relates to a
different provision of the Clean Air Act regarding implementation of
the prevention of significant deterioration (PSD) permitting program,
i.e., a program that applies in areas that have been designated
attainment of the NAAQS. The SILs Guidance is not applicable to the
interstate transport provision, which requires states to eliminate
significant contribution or interference with maintenance of the NAAQS
at known and ongoing air quality problem areas in other states. The EPA
does not, in this action, agree that the State has justified its
application of the 1 ppb threshold. In any case, both the EPA's most
recent modeling, EPA 2016v2 modeling, and the modeling relied on by
ADEQ in its SIP submittal, indicate that the State is projected to
contribute greater than both the 1 percent and alternative 1 ppb
thresholds. While the EPA does not, in this action, propose to 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, (as shown in Table AR-2) 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.
Additionally, 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 threshold at
Step 2. (The memorandum also indicated that any higher alternative
threshold, such as 2 ppb, would likely not be appropriate.) However,
the EPA also provided that ``air agencies should consider whether the
recommendations in this guidance are appropriate for each situation.''
Following receipt and review of 49 interstate transport SIP submittals
for the 2015 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
[[Page 9807]]
support approval.\47\ 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.
---------------------------------------------------------------------------
\47\ ``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 comments on this proposed approval and has not
taken final action with respect to this proposal.
---------------------------------------------------------------------------
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.\48\ The availability of different thresholds at Step 2 has
the potential to result in inconsistent application of interstate
transport 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
interstate transport 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 would 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.
---------------------------------------------------------------------------
\48\ 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.
---------------------------------------------------------------------------
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 memorandum that there was some
similarity in the amount of total upwind contribution captured (on a
nationwide basis) between 1 percent 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; \49\ in EPA 2016v2 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.
---------------------------------------------------------------------------
\49\ See August 2018 memorandum, at page 4.
---------------------------------------------------------------------------
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 memorandum 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 basis for the EPA's proposed
disapproval of ADEQ's SIP submission with respect to the Step 2
analysis is, in the Agency's view, warranted even under the terms of
the August 2018 memorandum. The EPA invites comment on this broader
discussion of issues associated with alternative thresholds at Step 2.
(See Supplementary Information section above for details and docket to
submit comments). Depending on public comments received in relation to
this action and further evaluation of this issue, the EPA may determine
to rescind the 2018 memorandum in the future.
ADEQ included information in its SIP submission regarding back
trajectories, emissions trends, and EGU cost controls to conclude that
emissions from Arkansas should not be considered to contribute
significantly to nonattainment or interfere with maintenance of the
NAAQS in other states because there is not a persistent and consistent
pattern of contribution from the State. While it is not entirely clear
whether ADEQ was analyzing these factors under Step 2 or Step 3, the
EPA is evaluating such arguments under Step 3, as we view these
statements in the SIP submission to speak to whether or not a
contribution is ``significant'' once a linkage is established.
3. Results of the EPA's Step 1 and Step 2 Modeling and Findings for
Arkansas
As described in Section I of this action, the EPA performed air
quality modeling using the 2016v2 emissions platform to project DVs and
contributions for 2023 (EPA 2016v2 modeling). This data was examined to
determine if Arkansas contributes at or above the threshold of 1
percent of the 2015 ozone NAAQS (0.70 ppb) to any downwind
nonattainment or maintenance receptor. As shown in Table AR-2, the data
\50\ indicate that in 2023, emissions from Arkansas contribute greater
than 1 percent of the standards to nonattainment or maintenance-only
receptors in Texas: Denton County (Monitor ID. 481210034), Brazoria
County (Monitor ID. 480391004), Harris County (Monitor ID. 482010055,
Monitor ID. 482011034,
[[Page 9808]]
and Monitor ID. 482011035).\51\ \52\ Therefore, based on the EPA's
evaluation of the information submitted by ADEQ, and based on the EPA
model 2016v2 results for 2023, the EPA proposes to find that Arkansas
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.
---------------------------------------------------------------------------
\50\ Design values and contributions at individual monitoring
sites nationwide are provided in the file:
2016v2_DVs_state_contributions.xlsx which is included in docket ID
No. EPA-HQ-OAR-2021-0663.
\51\ These modeling results are consistent with the results of a
prior round of 2023 modeling using the 2016v1 emissions platform
which became available to the public in the fall of 2020 in the
Revised CSAPR Update, as noted in Section I of this action. That
modeling showed that Arkansas had a maximum contribution greater
than 0.70 ppb to at least one nonattainment or maintenance-only
receptor in 2023. These modeling results are included in the file
``Ozone Design Values And Contributions Revised CSAPR Update.xlsx''
in docket EPA-HQ-OAR-2021-0663.
\52\ Allegan County Monitor ID. 260050003 is not a receptor in
2023 in the EPA 2016v2 modeling. 2023 avg DV is 67.3 ppb and 2023
Max. DV is 68.4 ppb, so the Allegan County monitor is not a receptor
in 2023 for nonattainment or maintenance.
Table AR-2--Projected Nonattainment and Maintenance Receptors With Arkansas Linkages in 2023 Based on EPA 2016v2
Modeling
----------------------------------------------------------------------------------------------------------------
Arkansas
Receptor (site ID, county, state) Nonattainment/ 2023 average 2023 maximum contribution
maintenance DV (ppb) DV (ppb) (ppb)
----------------------------------------------------------------------------------------------------------------
481210034, Denton, TX................. Maintenance............. 70.4 72.2 0.76
480391004, Brazoria, TX............... Maintenance............. 70.1 72.3 1.39
482010055, Harris, TX................. Nonattainment........... 71.0 72.0 1.00
482011034, Harris, TX................. Maintenance............. 70.3 71.6 1.38
482011035, Harris, TX................. Maintenance............. 68.0 71.6 1.34
----------------------------------------------------------------------------------------------------------------
We recognize that the results of the EPA modeling released in the
March 2018 memorandum (2011 base year) and the EPA 2016v2 modeling
(2016 base year) identified different receptors and linkages at Steps 1
and 2 of the 4-Step framework. These differing results about receptors
and linkages can be affected by the varying meteorology from year to
year, but we do not think the differing results mean that the modeling
or the EPA methodology for identifying receptors or linkages is
inherently unreliable. Rather, these separate modeling runs indicated
(1) that there were receptors that would struggle with nonattainment or
maintenance in the future, and (2) that Arkansas was linked to some set
of these receptors, even if the receptors and linkages differed from
one another in their specifics (e.g., a different set of receptors were
identified to have nonattainment or maintenance problems, or Arkansas
was linked to different receptors in one modeling run versus another).
We think this common result indicates that Arkansas's emissions were
substantial enough to generate linkages at Steps 1 and 2 to some set of
downwind receptors, under varying assumptions and meteorological
conditions, even if the precise set of linkages changed between
modeling runs. Under these circumstances, we think it is appropriate to
proceed to a Step 3 analysis to determine what portion of Arkansas's
emissions should be deemed ``significant.'' In doing so, we are not
considering our own earlier modeling results included in EPA's March
2018 memorandum to be of equal reliability relative to more recent EPA
2016v2 modeling. However, where alternative or older modeling generated
linkages, even if those linkages differ from linkages in EPA 2016v2
modeling, that information provides further evidence, not less, in
support of a conclusion that the state is required to proceed to Step 3
to further evaluate its emissions.
4. Evaluation of Information Provided by ADEQ Regarding Step 3
At Step 3 of the 4-Step 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 contribute
significantly to nonattainment or interfere with maintenance and, thus,
must be eliminated under CAA section 110(a)(2)(D)(i)(I).
ADEQ included in their SIP submission a further analysis of its
modeled linkage to Allegan, MI (the only linked receptor it analyzed,
based on its application of a 1 ppb threshold). Arkansas stated that
the purpose and its conclusion of this analysis was that it would not
contribute significantly to the Allegan, MI monitor because the state's
emissions did not result in a consistent and persistent pattern of
ozone contribution. As stated earlier, EPA 2016v2 modeling projects
that the Allegan County, MI receptor will be attaining and is not
expected to have difficulty maintaining the standard in 2023. As such,
the EPA is not relying on the comparative analysis of emissions trends
that ADEQ provided in order to conclude that Arkansas's emissions do
not contribute significantly to a nonattainment or maintenance problem
in Allegan, MI. We note however, that ADEQ's SIP submission and
response to comments do not clearly define what ADEQ considers to be
persistent and consistent pattern of contribution. Rather, the SIP
submission simply states that contribution should be deemed
``significant'' only if there is a persistent and consistent pattern of
several days with elevated ozone.
To be clear, the modeling establishing linkages of Arkansas to
downwind nonattainment and maintenance receptors already establishes
that there is a consistent and persistent pattern of contribution on
elevated ozone days from Arkansas to other states. That is because
EPA's methodology for projecting future year ozone concentrations
accounts for precisely these concerns--the relative response factor
\53\ that is applied to historic monitored data to generate projections
is calculated by looking only at days with elevated ozone levels (ten
days is preferred with a minimum of five days). The EPA notes that
monitored attainment with the ozone standard is determined by averaging
the fourth high value recorded each year for three years. So, the EPA
believes it is important to
[[Page 9809]]
estimate impacts on the days with highest projected ozone levels. The
EPA's approach, as detailed in the Air Quality Modeling Technical
Support Document for 2015 Ozone NAAQS Transport SIP Proposed Actions
included in Docket ID No. EPA-HQ-OAR-2021-0663, does this by estimating
the average fy 2023 impact from an upwind state on the days with the
highest projected ozone levels at the downwind nonattainment or
maintenance receptor. The days chosen to analyze the future impacts are
chosen initially by the selecting the ten highest days in the base
period modeling that are projected to be above 65 ppb in the base
period. If there are not ten days above 65 ppb at a potential receptor,
the number of days above 65 ppb are used as long as there is at least
five days above 65 ppb in the base period. If the air quality modeling
shows fewer than five days above 65 ppb in the base period, then the
data for impacts at that receptor in fy 2023 are not calculated. The
base and future year modeling for these five to ten days is then used
to project fy 2023 ozone DVs to determine whether it is projected to be
a nonattainment or maintenance receptor in 2023. For the same five to
ten days identified, the future year modeling provides the estimated
daily contribution at a potential receptor's future year daily MDA8 and
these daily contributions are averaged for the five to ten days to
result in the average contribution from the upwind area.
---------------------------------------------------------------------------
\53\ The relative response factor (RRF) is a ratio developed
using the modeled changes between the base case and future case for
high ozone modeled days. Typically, the 10 highest MDA8 modeled days
in the base case are found and the maximum value from the 3x3 grid
centered on the monitor for each day is used to calculate a 10-day
average base case modeled value. Then a similar concentration
average is developed for same 10 base case days and the same grid
cell that provided the base case concentration to calculate a future
year 10-day average modeled value using the future year modeling
results. The RRF is then calculated by using this future year 10-day
average model value divided by the base case year 10-day average
model value to develop a ratio representing the change in modeled
ozone. The RRF is then multiplied times the base DV value to result
in a projected future year DV.
---------------------------------------------------------------------------
As mentioned previously, ADEQ used HYSPLIT back trajectories to
assess wind patterns on elevated ozone days in an attempt to
demonstrate that there is not persistent and consistent pattern of
contribution from Arkansas to the Allegan County, MI receptor. HYSPLIT
back trajectory analyses use archived meteorological modeling that
includes actual observed data (surface, upper air, airplane data, etc.)
and modeled meteorological fields to estimate the most likely route of
an air parcel transported to a receptor at a specified time. The method
essentially follows a parcel of air backward in hourly steps for a
specified length of time. HYSPLIT estimates the central path in both
the vertical and horizontal planes. The HYSPLIT central path represents
the centerline with the understanding that there are areas on each side
horizontally and vertically that also contribute to the concentration
at the end point monitor. The horizontal and vertical areas that
potentially contribute to the end point concentration grow wider from
the centerline the further back in time the trajectory goes. Therefore,
a HYSPLIT centerline does not have to pass directly over emissions
sources or emission source areas but merely relatively near emission
source areas for those areas to contribute to concentrations at the
endpoint. The EPA relies on back trajectory analysis as a corollary
analysis along with observation-based meteorological wind fields at
multiple heights to examine the general plausibility of the
photochemical model ``linkages.'' Since the back trajectory
calculations do not account for any air pollution formation,
dispersion, transformation, or removal processes as influenced by
emissions, chemistry, deposition, etc., the trajectories cannot be used
to develop quantitative contributions. Therefore, back trajectories
cannot be used to quantitatively evaluate the magnitude of the existing
photochemical contributions from upwind states to downwind receptors.
Chemical transport models, such as the one relied upon by Arkansas to
establish the linkage between Arkansas and those downwind receptors in
the first instance, do take these factors into account and therefore
provide a more robust assessment of ozone contribution.
During ADEQ's public comment period, the EPA submitted comments
noting concerns regarding the methodology ADEQ used in their HYSPLIT
back trajectories analysis.\54\ While we are not providing a detailed
evaluation of ADEQ's HYSPLIT analysis in this rulemaking, we do note
that our review identified a number of concerns with how ADEQ screened
out a number of back trajectories, which invalidates ADEQ's
conclusions.\55\ While we disagree with ADEQ's methodologies and
conclusions, we note that ADEQ's HYSPLIT back trajectory information
did not show that the base years used in the EPA modeling (2011 and
2016) demonstrated an unusual amount of transport of air parcels from
Arkansas to nonattainment or maintenance receptors in downwind states
(i.e., the modeling years used by the EPA do not skew the results
toward finding linkages).\56\ Therefore, although Arkansas asserted
that its additional air quality factor analysis using back trajectory
analysis is a permissible way to interpret which contributions are
``significant'' because that analysis examines whether there was a
``persistent and consistent pattern of contribution on several days
with elevated ozone,'' the modeled linkage at Step 2 is a superior
approach for assessing the persistence of a state's contribution. It is
superior because it is based on the average of the contributions on the
five to ten highest ozone days. Considering the form of the standard,
this is a sufficient number of days to determine if an impact is
persistent enough to impact an area's ability to attain or maintain the
standard. The modeling is also a better method because it accounts for
dispersion while back trajectory analysis as performed by Arkansas only
shows the centerline of air parcel travel and otherwise will leave out
days when Arkansas would have contributed to downwind problems.
Finally, because the modeling accounts for dispersion and chemical
reactions, it can provide a quantitative estimate of contribution.
---------------------------------------------------------------------------
\54\ The EPA reviewed the ADEQ SIP submission and provided
comments during the State's public comment period for the proposed
SIP action. The EPA's comment letter and ADEQ's response to comments
are included in ADEQ's October 19, 2019, SIP submission, which is
available in the Regional docket for this action (Docket ID No. EPA-
R06-OAR-2021-0801).
\55\ Concerns included removing of HYSPLIT back trajectories
based on start height, the start time that Arkansas used for the
back trajectories and removing of back trajectories when the
centerline passed near but not through Arkansas because Arkansas has
some very large point sources near the Arkansas state line that
could be contributing. Texas also screened their HYPSLIT back
trajectories similarly to Arkansas and we have further discussed our
concerns and why such screening invalidates conclusions from the
HYSPLIT back trajectory analyses. See EPA's review and conclusions
in discussion of TCEQ's HYSPLIT analyses in the ``EPA Region 6 2015
8-Hour Ozone Transport SIP Proposal Technical Support Document''
(EPA Region 6 2015 Ozone Transport SIP TSD.pdf) included in the
Regional docket for this action (Docket ID No. EPA-R06-OAR-2021-
0801).
\56\ ADEQ's summary of trajectories indicated that 2011 had
three linked back trajectories and 2016 had one linked back
trajectories and the EPA calculated the average for 2008-2017 in
ADEQ's table was 2.2 linked back trajectories per year.
---------------------------------------------------------------------------
ADEQ also contested the significance of its modeled contribution
above 1 ppb based on the relatively larger contributions of other
upwind states to the receptor to which it was linked. The EPA disagrees
that a state's small contribution relative to other upwind states is a
permissible basis for finding no obligation under the interstate
transport provision. CAA 110(a)(2)(D)(i)(I) requires states and the EPA
to address interstate transport of air pollution that contributes to
downwind states' ability to attain and maintain the 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 an upwind state is significantly
contributing to that problem. States are not obligated under CAA
section 110(a)(2)(D)(i)(I) to reduce emissions sufficient on their own
to resolve
[[Page 9810]]
downwind receptors' nonattainment or maintenance problems. Rather,
states are obligated to eliminate their 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 arguments suggesting that upwind states should be
excused from interstate transport 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 these
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 emissions from other states also
contribute some amount of pollution to the same receptors to which the
state is linked.
ADEQ did not provide additional analysis for other receptors to
which it was linked above 1 percent in the air quality modeling upon
which it relied, and to which it continues to be linked in EPA 2016v2
modeling. To effectively evaluate 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. As discussed below,
ADEQ did not conduct an adequate analysis in their SIP submission. We
therefore propose that ADEQ 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 Arkansas failed to adequately do so.
In analyzing potential additional NOX controls, ADEQ
found that additional controls on its EGUs would exceed the cost-
effectiveness thresholds identified in the CSAPR and CSAPR Update
rules. For the cost analysis, Arkansas only focused on the potential
costs of NOX controls for EGUs. As stated above, Arkansas
found that the costs to install additional NOX controls
(selective catalytic reduction, SCR, and selective noncatalytic
reduction, SNCR) at electric generating units (EGUs) exceed EPA's cost
thresholds used for the CSAPR and CSAPR Update rules. Based on the
projected cost of these controls relative to the thresholds used in
those two prior EPA rules, Arkansas concluded that no new controls
beyond those Federal and State regulations already in existence were
cost-effective, especially considering that Allegan County, MI is
projected to be in attainment with the 2015 ozone NAAQS and Arkansas's
small contribution relative to other states potentially linked to
Allegan County, MI based on EPA's modeling.
Arkansas's analysis is inadequate because its focus is only on
EGUs.\57\ See Wisconsin, 938 F.3d at 318-20. We also find Arkansas's
conclusions as to the availability of cost-effective controls for EGUs
to be inadequate. Relying on the CSAPR Update's (or any other CAA
program's) determination of cost-effectiveness without further Step 3
analysis is not approvable. Cost-effectiveness must be assessed in the
context of the specific CAA program; assessing cost-effectiveness in
the context of ozone transport should reflect a more comprehensive
evaluation of the nature of the interstate transport problem, the total
emissions reductions available at several cost thresholds, and the
potential air quality impacts of those reductions at downwind
receptors. While the EPA has not established a benchmark cost-
effectiveness value for 2015 ozone NAAQS interstate transport
obligations, because the 2015 ozone NAAQS is a more stringent and more
protective air quality standard, it is reasonable to expect control
measures or strategies to address interstate transport under this NAAQS
to reflect higher marginal control costs. ADEQ's submission failed to
provide a justification for why the $1400/ton threshold used in the
CSAPR Update is appropriate to rely on for the 2015 ozone NAAQS. ADEQ's
analysis does not consider any air quality impacts of assessed controls
at downwind receptors. As stated above, assessing cost-effectiveness in
the context of ozone transport requires more than just assessing the
cost of controls per ton of NOX removed. As such, ADEQ's
assessment of the cost of controls and reliance on the marginal cost
threshold of $1,400/ton used for the CSAPR Update is inadequate.
Furthermore, EPA 2016v2 modeling captures all existing CSAPR trading
programs in the baseline and confirms that these control programs were
not sufficient to eliminate Arkansas's linkage at Steps 1 and 2 under
the 2015 ozone NAAQS. The State was therefore obligated at Step 3 to
assess additional control measures using a multifactor analysis.
---------------------------------------------------------------------------
\57\ In 2017, National Emission Inventory (NEI) NOX
emissions from EGU sources represent 56% percent of the total NOx
emissions categories in Arkansas that report emissions to the NEI.
See AR NOx.xlsx datasheet included in the Regional docket for this
action (Docket ID No. EPA-R06-OAR-2021-0801).
---------------------------------------------------------------------------
[[Page 9811]]
5. Evaluation of Information Provided by ADEQ Regarding Step 4
Step 4 of the 4-Step interstate transport framework calls for the
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. ADEQ's SIP submission,
which looked only at additional NOX controls at EGUs and
dismissed such controls as not cost-effective relative to the
thresholds established in earlier EPA transport rules, did not
constitute an adequate emission reduction analysis at Step 3. Based on
its conclusions, ADEQ did not revise its SIP to include any emission
reductions. As a result, the EPA proposes to disapprove ADEQ's
submittal on the separate, additional basis that Arkansas has not
developed or included permanent and enforceable emissions reductions in
its SIP necessary to meet the obligations of CAA section
110(a)(2)(D)(i)(I).
6. Conclusion
Based on the EPA's evaluation of ADEQ's SIP submission, the EPA is
proposing to find that ADEQ's October 19, 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 ozone NAAQS in any other state.
III. Louisiana SIP Submission Addressing Interstate Transport of Air
Pollution for the 2015 Ozone NAAQS and the EPA Evaluation of the SIP
Submission
A. Summary of LDEQ SIP Submission Addressing Interstate Transport of
Air Pollution for the 2015 Ozone NAAQS
On November 13, 2019, the Louisiana Department of Environmental
Quality (LDEQ) made a SIP submission addressing the State of
Louisiana's interstate transport of air pollution for the 2015 ozone
NAAQS. The SIP submission provided LDEQ's analysis of Louisiana's
impact to downwind states and concluded that emissions from Louisiana
will not contribute significantly to nonattainment or interfere with
maintenance of the 2015 ozone NAAQS in other states.
The LDEQ's SIP submission provided an analysis of Louisiana's air
emissions impact to downwind states using a 3-Step alternative
framework similar to the EPA's 4-Step framework. LDEQ's 3-Step
alternative framework includes: Step 1: Identify monitors projected to
be in nonattainment or have maintenance issues in a future year; Step
2: Identify projected nonattainment and/or maintenance monitors in
other states that might be impacted by emissions from Louisiana,
tagging them for further review; and, Step 3: Determine if emissions
from Louisiana contribute significantly to nonattainment or interfere
with maintenance at the monitors tagged for review in Step 2. LDEQ
noted that its Step 1 is identical to the EPA's Step 1, and its Steps 2
and 3 are equivalent to the EPA's Step 2. Louisiana further noted that
Steps 3 and 4 of the EPA's 4-Step framework are relevant only if
emissions from Louisiana contribute significantly to nonattainment or
interfere with maintenance at downwind monitors in another state.
LDEQ's Step 1 was to identify downwind monitors projected to be in
nonattainment and/or have maintenance issues in future year 2023 (fy
2023). At this step, LDEQ relied on the EPA's interstate transport
modeling results that are included as an attachment to the March 2018
memorandum. The EPA March 2018 modeling results provided: (1) Projected
average DV and maximum DV for 2023 for the ozone monitors (or
``receptors'') in the 48 contiguous states and (2) the expected
contribution of state emissions to the projected ozone concentrations
at each ozone monitor.
LDEQ used a contribution threshold of 1 ppb in LDEQ's Step 2 to
identify projected nonattainment and/or maintenance receptors in other
states that might be impacted by emissions from Louisiana and tagged
them for further review. To support a 1 ppb contribution threshold,
LDEQ's submission stated that a 1 percent threshold is inappropriate
because that value is not detectable by a monitor and the value of 1
percent of the 2015 ozone NAAQS would be truncated to zero if
calculated in accordance with the method for determining DVs for the
ozone NAAQS. LDEQ also stated that the more stringent threshold of 1
percent of the NAAQS (0.7 ppb) is an order of magnitude smaller than
the biases and errors typically documented for regional photochemical
modeling.\58\ Based on LDEQ's approach of evaluating linkages at the 1
ppb threshold, five Texas receptors were identified by Louisiana for
analysis. The Texas receptors and corresponding receptor data presented
in Louisiana's SIP are summarized further in this notice in Table LA-
1.\59\ The March 2018 memorandum identified monitors in Allegan,
Michigan and Milwaukee and Sheboygan, Wisconsin as potential
nonattainment and maintenance-only receptors linked to emissions from
Louisiana based on 1 percent of the NAAQS threshold. However, Louisiana
did not include the Allegan, Michigan and Milwaukee and Sheboygan,
Wisconsin receptors in the State's analysis because the March 2018
memorandum shows that Louisiana's projected modeled contribution values
to each receptor is less than 1 ppb.
---------------------------------------------------------------------------
\58\ The Louisiana SIP submittal did not provide a specific
citation to the Simon et al., 2012 reference to support this
assertion. However, we believe the reference is associated with the
following article: Simon, H., Baker, K.R., Phillips, S., 2012.
``Compilation and interpretation of photochemical model performance
statistics published between 2006 and 2012''. Atmospheric
Environment 61, 124-139.
\59\ The five potential nonattainment and maintenance receptor
monitors identified by LDEQ are from the Dallas-Fort Worth and
Houston-Galveston-Brazoria, TX nonattainment areas for the 2015
ozone NAAQS. The Louisiana SIP submittal appears to have
inadvertently omitted Harris County, TX Monitor ID No. 482011034 for
analysis. EPA's March 2018 memorandum identified this monitor as a
maintenance receptor with a contribution of 3.38 ppb from Louisiana
emissions.
Table LA-1--Projected Nonattainment and Maintenance Receptors Identified by Louisiana Based on the EPA's March
2018 Memorandum
----------------------------------------------------------------------------------------------------------------
Louisiana
Receptor (site ID, county, state) 2023 Average 2023 Maximum Contribution
DV (ppb) \60\ DV (ppb) \61\ (ppb)
----------------------------------------------------------------------------------------------------------------
480391004, Brazoria, TX......................................... 74.0 74.9 3.80
[[Page 9812]]
482011039, Harris, TX........................................... 71.8 73.5 4.72
484392003, Tarrant, TX.......................................... 72.5 74.8 1.71
481210034, Denton, TX........................................... 69.7 72.0 1.92
482010024, Harris, TX........................................... 70.4 72.8 4.72
----------------------------------------------------------------------------------------------------------------
For LDEQ's Step 3, Louisiana stated that an air emission
contribution from the State should only be considered significant if
there is a persistent and consistent pattern of contribution on several
days with elevated ozone. In trying to determine whether there is a
persistent and consistent pattern of contribution, LDEQ analyzed
seasonal weather patterns, surface wind directions, and periodic back
trajectories. LDEQ used the National Oceanic and Atmospheric
Administration (NOAA) Hybrid Single Particle Lagrangian Integrated
Trajectory (HYSPLIT) \62\ model to perform 99 back trajectories for
exceedances from the receptor monitors identified in Table LA-1 for
2016, 2017, and 2018. Based on an analysis of the HYSPLIT results, LDEQ
stated that approximately 28% of the trajectories travel in or through
Louisiana, and only 8% of those back trajectories originate in the
State. The SIP submission also stated that a comparison of the EPA's
modeled contribution between Texas and Louisiana monitors indicates
that a far greater proportion of the total ozone detected in Louisiana
originates in Texas rather than vice versa. Therefore, Louisiana
concluded that the impact from the State's air emissions was
insignificant to the overall attainment at the receptor monitors
identified in Table LA-1 and does not significantly contribute to
nonattainment or interfere with maintenance of the 2015 ozone NAAQS in
other states.
---------------------------------------------------------------------------
\60\ Information added from the EPA's March 2018 memorandum.
\61\ Id.
\62\ See FN 34.
---------------------------------------------------------------------------
B. EPA Evaluation of the LDEQ SIP Submission
The EPA is proposing to find that LDEQ's November 13, 2019, SIP
submission does not meet the State's obligations with respect to
prohibiting emissions that contribute significantly to nonattainment or
interfere with maintenance of the 2015 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 Louisiana's SIP submission.
1. Evaluation of Information Provided by LDEQ Regarding Steps 1 and 2
At Step 1 of the 4-Step interstate transport framework, LDEQ relied
on EPA modeling released in the March 2018 memorandum to identify
nonattainment and maintenance receptors in 2023. At Step 2 of the 4-
Step interstate transport framework, LDEQ relied on the EPA modeling
released in the March 2018 memorandum to identify upwind state linkages
to nonattainment and maintenance receptors in 2023. LDEQ additionally
utilized a 1 ppb threshold at Step 2 to identify 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, as an alternative to a 1 percent
threshold, at Step 2 of the 4-Step interstate transport framework, for
the purposes of identifying linkages to downwind receptors. In any
case, the State is projected to contribute greater than both the 1
percent and the alternative 1 ppb thresholds to receptors in Texas,
regardless of whether we look at LDEQ's analysis (which relied on the
EPA's older modeling) or updated modeling the EPA has performed in
advance of this proposal. As seen in the tables LA-1 and LA-2,
Louisiana contributes nearly five times the 1 ppb threshold to
nonattainment or maintenance receptors in Texas. Therefore, 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 threshold at Step
2.\63\ (The memorandum also indicated that any higher alternative
threshold, such as 2 ppb, would likely not be appropriate.) However,
the EPA also provided that ``air agencies should consider whether the
recommendations in this guidance are appropriate for each situation.''
Following receipt and review of 49 interstate transport SIP submittals
for the 2015 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.
---------------------------------------------------------------------------
\63\ See August 2018 memorandum, at page 4.
---------------------------------------------------------------------------
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.\64\ 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.
---------------------------------------------------------------------------
\64\ ``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 comments on this proposed approval and has not
taken final action with respect to this proposal.
---------------------------------------------------------------------------
Furthermore, the EPA's experience since 2018 is that allowing for
alternative Step 2 thresholds may be
[[Page 9813]]
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.\65\ The availability of different thresholds at Step 2 has
the potential to result in inconsistent application of interstate
transport 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
interstate transport 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 would 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.
---------------------------------------------------------------------------
\65\ 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.
---------------------------------------------------------------------------
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 memorandum that there was some
similarity in the amount of total upwind contribution captured (on a
nationwide basis) between 1 percent and 1 ppb. However, the EPA notes
that while this may be true in some sense, that is not 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; \66\ 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.
---------------------------------------------------------------------------
\66\ See August 2018 memorandum, at page 4.
---------------------------------------------------------------------------
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 memorandum 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 basis for a proposed
disapproval of LDEQ's SIP submission with respect to the Step 2
analysis we believe is warranted under the terms of the August 2018
memorandum. The EPA invites comment on this broader discussion of
issues associated with alternative thresholds at Step 2. Depending on
public comments received and further evaluation of this issue, the EPA
may determine to rescind the 2018 memorandum in the future.
2. Results of the EPA's Step 1 and Step 2 Modeling and Findings for
Louisiana
As described in Section I of this action, the EPA performed air
quality modeling using the 2016v2 emissions platform to project DVs and
contributions for 2023.\67\ This data was examined to determine if
Louisiana contributes at or above the threshold of 1 percent of the
2015 ozone NAAQS (0.70 ppb) to any downwind nonattainment or
maintenance receptor. As shown in Table LA-2, the data \68\ indicate
that in 2023, emissions from Louisiana contributed greater than 1
percent of the standards to nonattainment or maintenance-only receptors
in Texas.\69\ Therefore, based on the EPA's evaluation of the
information submitted by LDEQ, and based on the EPA's most recent
modeling results for 2023, the EPA proposes to find that Louisiana 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.
---------------------------------------------------------------------------
\67\ Per the instructions in the Supplementary Information
section above, all public comments, including comments on the EPA's
air quality modeling should be submitted in the Regional docket for
this action, Docket ID No. EPA-R06-OAR-2021-0801. Comments are not
being accepted in Docket No. EPA-HQ-OAR-2021-0663.
\68\ DVs and contributions at individual monitoring sites
nationwide are provided in the file:
``2016v2_DVs_state_contributions.xlsx'', which is included in Docket
ID No. EPA-HQ-OAR-2021-0663.
\69\ These modeling results are consistent with the results of a
prior round of 2023 modeling using the 2016v1 emissions platform,
which became available to the public in the fall of 2020 in the
Revised CSAPR Update, as noted in Section I of this action. That
modeling showed that Louisiana had a maximum contribution greater
than 0.70 ppb to at least one nonattainment or maintenance-only
receptor in 2023. These modeling results are included in the file
``Ozone DVs And Contributions Revised CSAPR Update.xlsx'' in Docket
No. EPA-HQ-OAR-2021-0663.
Table LA-2--Projected Nonattainment and Maintenance Receptors With Louisiana Linkages Based on EPA 2016v2
Modeling
----------------------------------------------------------------------------------------------------------------
Louisiana
Receptor (site ID, county, state) Nonattainment/ 2023 Average 2023 Maximum Contribution
maintenance DV (ppb) DV (ppb) (ppb)
----------------------------------------------------------------------------------------------------------------
482010024, Harris, TX................. Nonattainment........... 75.2 76.8 4.31
482010055, Harris, TX................. Nonattainment........... 71.0 72.0 5.39
480391004, Brazoria, TX............... Maintenance............. 70.1 72.3 7.03
[[Page 9814]]
481210034, Denton, TX................. Maintenance............. 70.4 72.2 3.22
482011034, Harris, TX................. Maintenance............. 70.3 71.6 4.93
482011035, Harris, TX................. Maintenance............. 68.0 71.6 4.77
----------------------------------------------------------------------------------------------------------------
3. Evaluation of Information Provided by LDEQ 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 contribute significantly to nonattainment or interfere
with maintenance and, thus, must be eliminated under CAA section
110(a)(2)(D)(i)(I).
To effectively evaluate 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 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 an analysis similar to the EPA's (or an
alternative approach to defining ``significance'' that comports with
CAA requirements) to determine whether, and to what degree, emissions
from a state should be ``prohibited'' to eliminate emissions that will
``contribute significantly to nonattainment, or interfere with
maintenance of'' the NAAQS in any other state. LDEQ did not conduct
such an analysis in their SIP submission. Instead LDEQ interpreted the
Act's requirements as only requiring an analysis of emission reductions
where there was a ``consistent and persistent'' pattern of contribution
and conducted an air-quality-only analysis in order to refute such a
pattern. We propose to find that LDEQ was required to analyze emissions
from the sources and other emissions activity from within Louisiana to
determine whether its contributions were significant, and we propose to
disapprove its submission because LDEQ did not do so.
As noted, LDEQ stated in its SIP submission that emissions from
Louisiana should not be considered to contribute significantly to
nonattainment or interfere with maintenance of the NAAQS in other
states because there is not a ``persistent and consistent'' pattern of
contribution from the State. The SIP submission does not explain what
LDEQ considers to be a persistent and consistent pattern of
contribution, even after the LDEQ received a comment during its state
comment period that requested that the LDEQ define ``persistent and
consistent'' in terms of impacts on downwind states. The LDEQ
responded, ``Louisiana has defined the pattern and has provided back
trajectories on those monitored exceedances for the 2016-2018 ozone
seasons, which will show that the definition is applicable to the
conclusion.'' \70\ We do not agree that this suffices as an explanation
as to why LDEQ does not need to further analyze its potential emission
reductions under Step 3 before determining it has no statutory
obligation under the interstate transport provision. In the case of
Louisiana, modeling in the March 2018 memorandum and the EPA's more
recent 2016v2 modeling both project that receptors in the Houston-
Galveston-Brazoria (HGB) and Dallas-Fort Worth (DFW) ozone
nonattainment areas in Texas will have difficulty attaining or
maintaining the 2015 ozone NAAQS, and Louisiana's contribution to these
areas exceed both a 1 percent or a 1 ppb threshold. While linkages to
specific receptors may change with updated modeling, both modeling
analyses consistently show emissions from Louisiana impact both
downwind nonattainment receptors and downwind maintenance receptors in
Texas.
---------------------------------------------------------------------------
\70\ See LDEQ SIP Submission, Appendix A, available in the
Regional docket for this action (Docket ID No. EPA-R06-OAR-2021-
0801).
---------------------------------------------------------------------------
The LDEQ SIP submission stated that Louisiana's contribution should
be deemed ``significant'' per CAA section 110(a)(2)(D)(i)(I) only if
there is a persistent and consistent pattern of contribution on several
days with elevated ozone. LDEQ asserted that its linkages to Texas do
not warrant further analysis because, according to LDEQ, emissions from
Louisiana do not persistently and consistently contribute on several
days of elevated ozone. However, the EPA modeling that LDEQ relied upon
to demonstrate linkages in the first instance already establishes that
there is a consistent and persistent pattern of contribution from
Louisiana to Texas receptors on elevated ozone days. The EPA's
methodology for projecting future year ozone concentrations accounts
for precisely these concerns--the relative response factor \71\ that is
applied to historic monitored data to generate projections is
calculated by looking only at days with elevated ozone levels. The EPA
notes that monitored attainment with the ozone standard is determined
by averaging the fourth high value recorded each year for three years.
So, the EPA believes it is important to estimate impacts on the days
with highest projected ozone levels. The days chosen to analyze the
future impacts are chosen initially by the selecting the 10 highest
days in the base period modeling that are projected to be above 65 ppb
in the base period. If there are not 10 days above 65 ppb at a
potential receptor, the number of days above 65 ppb are used so long as
there is at least five days above 65 ppb in the base period. If the air
quality modeling shows fewer than five days above 65 ppb in the base
period, then the data for impacts at that receptor in 2023 are not
calculated. The base and future year modeling for these
[[Page 9815]]
5-10 days are then used to project 2023 ozone DVs to determine whether
it is projected to be a nonattainment or maintenance receptor in 2023.
For these same 5-10 days identified, the future year modeling provides
the estimated daily contribution at a potential receptor's future year
daily MDA8 and these daily contributions are averaged for the 5-10 days
to result in the average contribution from the upwind area.
---------------------------------------------------------------------------
\71\ See FN 53.
---------------------------------------------------------------------------
LDEQ's air quality analysis used to dismiss its linkages to Texas
receptors as not ``significant'' consists of an evaluation of seasonal
weather patterns, surface wind directions, and periodic back
trajectories. The State's weather pattern analysis relied on large-
scale weather patterns as they relate to commonly observed wind
directions rather than weather patterns and conditions that are
specifically conducive to ozone formation or tied to specific days when
high ozone was monitored in the downwind areas. General weather pattern
discussions that are not associated with specific ozone episodes are
not generally informative of interstate transport decisions. It is
necessary to investigate specific instances of high ozone, because as
discussed previously, violations of the ozone standard can be driven by
as few as 4 days per year because the compliance with the standard is
evaluated based on the average of the fourth high value measured each
of three consecutive years.
LDEQ's wind rose analysis is based on surface sites in the Dallas-
Fort Worth areas, Houston-Galveston-Brazoria areas, and other areas in
Texas and Louisiana, but the analysis does not address transport winds
between Louisiana and the Texas areas with receptors on high ozone days
at the identified receptors. There are several limitations associated
with LDEQ's wind rose analysis: (1) Wind directions measured at the
surface are not necessarily good indicators of the wind direction
occurring at higher elevations, which tend to have a stronger influence
on interstate ozone transport; (2) wind directions change spatially
over the range of distance involved in transport from Louisiana to
Texas; (3) wind directions change temporally over the range of time
involved in ozone transport from Louisiana to Texas; and (4) the wind
roses are based on wind data measured throughout the year, not just
during either ozone season or monitored ozone episode days. In
addition, as discussed previously, LDEQ's wind rose analysis is not
limited to the wind conditions that are conducive to high ozone, so it
does not provide information directly pertinent to when ozone is high
at areas in Texas and whether Louisiana is a contributing area during
those specific times.
LDEQ also included 99 back trajectory analyses during the 2016,
2017, and 2018 years for the dates of ozone exceedances at the monitors
referenced in Table LA-1 of this action. HYSPLIT back trajectory
analyses use archived meteorological modeling that includes actual
observed data (surface, upper air, airplane data, etc.) and modeled
meteorological fields to estimate the most likely route of an air
parcel transported to a receptor at a specified time. The method
essentially follows a parcel of air backward in hourly steps for a
specified length of time. HYSPLIT estimates the central path in both
the vertical and horizontal planes. The HYSPLIT central path represents
the centerline with the understanding that there are areas on each side
horizontally and vertically that also contribute to the concentrations
at the end point. The horizontal and vertical areas that potentially
contribute to concentrations at the endpoint grow wider from the
centerline the further back in time the trajectory goes. Therefore, a
HYSPLIT centerline does not have to pass directly over emissions
sources or emission source areas but merely relatively near emission
source areas for those areas to contribute to concentrations at the
trajectory endpoint. The EPA relies on back trajectory analysis as a
corollary analysis along with observation-based meteorological wind
fields at multiple heights to examine the general plausibility of the
photochemical model ``linkages.'' Since the back trajectory
calculations do not account for any air pollution formation,
dispersion, transformation, or removal processes as influenced by
emissions, chemistry, deposition, etc., the trajectories cannot be used
to develop quantitative contributions. Therefore, back trajectories
cannot be used to quantitatively evaluate the magnitude of the existing
photochemical contributions from upwind states to downwind receptors.
LDEQ's HYSPLIT back trajectory analysis for 2016, 2017, and 2018 showed
that on high ozone days in Texas at the receptors identified by the EPA
in the 2018 memorandum that 28% of the trajectories passed through
Louisiana. LDEQ proffered that some of these back trajectories did not
pass directly over areas with emissions but did not consider that the
back trajectories only represent a centerline and there are areas on
either side of the centerline that would be contributing areas. LDEQ's
trajectory analysis confirmed that Louisiana is an upwind area for the
receptors in Texas often enough to potentially contribute to
nonattainment or interfere with maintenance. The analysis did not
provide evidence that was contrary to the conclusions of the EPA's
photochemical modeling analyses (i.e., the EPA's modeling results in
the March 2018 memorandum and EPA 2016v2 model).
Photochemical modeling simulations for ozone interstate transport
assessment is relied upon by the EPA to simulate the formation and fate
of oxidant precursors, primary and secondary particulate matter
concentrations, and deposition over regional and urban spatial scales.
Photochemical modeling is the most sophisticated tool available to
estimate future ozone levels and contributions to those modeled future
ozone levels. Consideration of the different processes that affect
primary and secondary pollutants at the regional scale in different
locations is fundamental to understanding and assessing the effects of
emissions on air quality concentrations. For the 2015 ozone NAAQS
interstate transport analysis, the EPA performed nationwide, state-
level ozone source apportionment modeling using CAMx to quantify the
contribution of NOX and VOC emissions from all sources in
each state to project 2023 ozone concentrations at ozone monitoring
sites. Detailed information for the EPA's modeling may be found in the
Air Quality Modeling TSD in Docket No. EPA-HQ-OAR-2021-0663.
LDEQ concluded in the SIP submittal, citing an article \72\
published in 2012, that the use of 1 percent of the standard for
modeled contribution as the sole definition of significant contribution
is inappropriate for the 2015 ozone NAAQS. LDEQ's reasoning for this
conclusion is that the more stringent 0.7 ppb threshold ``is an order
of magnitude smaller than the biases and errors typically documented
for regional photochemical modeling.'' First, the EPA does not use the
1 percent threshold as the sole definition of significant contribution;
at Step 2 of the analysis, the 1 percent threshold is used to identify
contributions between states and downwind problem areas for further
analysis at Step 3. Second, photochemical transport models such as CAMx
have been extensively peer reviewed and used to support SIPs and
explore relationships between inputs and air quality impacts in the
U.S. and beyond. The EPA works to continually develop and update both
the guidelines
[[Page 9816]]
on using modeling results and the latest versions of photochemical
model platforms to support scientific assessments and regulatory
determinations. Prior to using photochemical modeling to support a
regulatory assessment, a model performance evaluation is completed to
establish a benchmark to assess how accurately the model predicts
observed concentrations and to identify model limitations. The model
performance evaluation provides a better understanding of the model's
limitations and biases and serves as a diagnostic evaluation for
further model development and improvement. As discussed in Section I of
this document and the Air Quality Modeling TSD in Docket No. EPA-HQ-
OAR-2021-0663, the EPA follows the most recent established modeling
guidance and provides with this action the updated modeling analysis
based on the recent CAMx model update. By using the most recent 2016v2
photochemical modeling enhancements (EPA 2016v2 modeling) results are
more representative of the projected local and regional air quality as
it is based on more recent emission estimates with fewer years between
the base case year (2016) and the future year (2023). In addition, to
reduce the impact of any potential biases or errors, the EPA uses the
modeling results in a relative sense rather than rely on absolute model
predictions.\73\
---------------------------------------------------------------------------
\72\ Simon et al., supra FN 58.
\73\ See ``Modeling Guidance for Demonstrating Air Quality Goals
for Ozone, PM2.5 and Regional Haze'', Nov. 29, 2018, at
101, available at https://www.epa.gov/sites/default/files/2020-10/documents/o3-pm-rh-modeling_guidance-2018.pdf (``2018 Air Quality
Modeling Guidance''). See also ``Draft Modeling Guidance for
Demonstrating Attainment of Air Quality Goals for Ozone,
PM2.5, and Regional Haze'', Dec. 3, 2014, at 97-98,
available at https://www.epa.gov/sites/default/files/2020-10/documents/draft-o3-pm-rh-modeling_guidance-2014.pdf (``2014 Draft
Air Quality Modeling Guidance'').
---------------------------------------------------------------------------
Furthermore, it is not appropriate to compare the bias/error
involved in the estimation of total ozone to the potential error in the
estimation of the subset of ozone that is contributed by a single
state. For example, on a specific day the modeled vs. monitored ozone
value may differ by 2 ppb but that is relatively small percentage of
the total modeled ozone, which for a receptor of interest would be on
the order of 70 ppb. It would be unrealistic to assign all the 2 ppb,
in the above example, to the estimated impact from a single state as
the 2 ppb error would be the combination of the error from all sources
of ozone that contribute to the total, including estimated impacts from
other states, the home state of the receptor and natural background
emissions.
In sum, the EPA disagrees that the estimates of potential error in
the models estimates of total ozone, call into question the use of 1
percent as a threshold for linkage. As noted earlier, in the case of
Louisiana, the difference between a 1 percent threshold and a 1 ppb
threshold is irrelevant to the decision here because linkages are
present at both threshold levels. As to Louisiana's conclusion that the
impacts from Louisiana's emissions are not persistent, the contribution
analysis is the average impact for at least 5 days and up to 10 days
for the 2016 base period which is sufficiently persistent considering
the first through fourth high monitored values set the monitored DV.
We recognize that the results of the EPA (2011 and 2016 base year)
modeling indicated different receptors and linkages at Steps 1 and 2 of
the 4-Step interstate transport framework. These differing results
regarding receptors and linkages can be affected by the varying
meteorology from year to year, but we do not think the differing
results means that the modeling or the EPA or the state's methodology
for identifying receptors or linkages is inherently unreliable. Rather,
these separate modeling runs all indicated: (1) That there are
receptors that would struggle with nonattainment or maintenance in the
future; and (2) that Louisiana is linked to some set of these
receptors, even if the receptors and linkages differed from one another
in their specifics (e.g., Louisiana was linked to a different set of
receptors in one modeling run versus another). These results indicates
that Louisiana's emissions were substantial enough to generate linkages
at Steps 1 and 2 to at least some set of downwind receptors, under
varying assumptions and meteorological conditions, even if the precise
set of linkages changed between modeling runs.
4. Evaluation of Information Provided by LDEQ 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,
LDEQ'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. To
the extent that LDEQ discussed emissions reductions, the State only
provided a summary of existing already implemented enforceable control
regulations. The EPA's 2016v2 modeling analyses have already accounted
for the implementation of the regulations cited by LDEQ's submission--
including the CSAPR rulemakings and prior regional rulemakings--and
even with those reductions in place, the modeling results consistently
show receptors that are projected to be in nonattainment or to struggle
with maintenance, and Louisiana contributing to those receptors.
Relying only on the existing enforceable control regulations is
insufficient to address the Louisiana air emission contributions to
linked downwind air quality problems. As a result, the EPA proposes to
disapprove LDEQ's 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).
5. Conclusion
Based on the EPA's evaluation of LDEQ's SIP submission, the EPA is
proposing to find that LDEQ's November 13, 2019, SIP submission
pertaining to interstate transport of air pollution 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 ozone NAAQS in any other state.
IV. Oklahoma SIP Submission Addressing Interstate Transport of Air
Pollution for the 2015 Ozone NAAQS and the EPA Evaluation of the SIP
Submission
A. Summary of ODEQ SIP Submission Addressing Interstate Transport of
Air Pollution for the 2015 Ozone NAAQS
On October 25, 2018, the Oklahoma Department of Environmental
Quality (ODEQ) made a SIP submission addressing interstate transport of
air pollution for the 2015 ozone NAAQS. The SIP submission provided
ODEQ's analysis of their impact to downwind states using the EPA's 4-
Step framework and an analytic year of 2023 and concluded that
emissions from Oklahoma will not contribute significantly to
nonattainment or interfere with maintenance of the 2015 ozone NAAQS in
other states.
To identify downwind air quality problems that are linked to
emissions
[[Page 9817]]
from Oklahoma and therefore warrant further review and analysis (Steps
1 and 2), ODEQ used EPA interstate transport modeling results found in
the March 2018 memorandum. The EPA modeling results projected: (1) An
average DV and a maximum DV for the year 2023 for ozone monitors in the
48 contiguous States and (2) the expected contribution from emissions
in each state to the ozone concentrations at each ozone monitor.
ODEQ used the information from the March 2018 EPA memorandum to
identify six downwind nonattainment and maintenance receptors \74\ with
a contribution from Oklahoma of 1 percent of the 2015 ozone NAAQS (0.70
parts ppb) or greater. ODEQ then applied a 1 ppb threshold to remove
from further analysis three receptors with a contribution from Oklahoma
of less than 1 ppb. ODEQ noted that the possibility of using an
alternative contribution threshold was one of the areas of flexibility
identified in the March 2018 EPA memorandum and discussed further in
the August 2018 EPA memorandum. To support its alternative contribution
threshold, ODEQ referenced an EPA memorandum from April 17, 2018, which
recommended a Significant Impact Level (SIL) for ozone of 1.0 ppb for
proposed sources subject to the Prevention of Significant Deterioration
(PSD) permitting program.\75\ Table OK-1 provides information on the
six nonattainment and maintenance receptors identified by ODEQ,
including the three receptors ODEQ identified for further analysis.
---------------------------------------------------------------------------
\74\ Nonattainment receptors are monitoring sites that are
anticipated to have problems attaining and maintaining the 2015
ozone NAAQS (i.e., average projected 2023 DV greater than 70.9 ppb).
Maintenance receptors are monitoring sites that are anticipated to
have problems maintaining the 2015 ozone NAAQS (i.e., maximum
projected 2023 DV greater than 70.9 ppb).
\75\ See FN 32.
Table OK-1--Nonattainment and Maintenance Receptors Identified by ODEQ Based on the EPA's March 2018 Memorandum
----------------------------------------------------------------------------------------------------------------
Oklahoma
Receptor (site ID, county, state) 2023 average 2023 maximum contribution ODEQ's step 1 and 2
DV (ppb) DV (ppb) (ppb) determination
----------------------------------------------------------------------------------------------------------------
260050003, Allegan, MI................ 69.0 71.7 1.31 Maintenance receptor
identified for further
analysis.
481210034, Denton, TX................. 69.7 72.0 1.23 Maintenance receptor
identified for further
analysis.
484392003, Tarrant, TX................ 72.5 74.8 1.71 Nonattainment receptor
identified for further
analysis.
480391004, Brazoria, TX............... 74.0 74.9 0.90 Nonattainment receptor
with contribution less
than 1 ppb; no further
analysis.
550790085, Milwaukee, WI.............. 71.2 73.0 0.76 Nonattainment receptor
with contribution less
than 1 ppb; no further
analysis.
551170006, Sheboygan, WI.............. 72.8 75.1 0.95 Nonattainment receptor
with contribution less
than 1 ppb; no further
analysis.
----------------------------------------------------------------------------------------------------------------
ODEQ further evaluated the two Texas receptors (Tarrant County and
Denton County) and the receptor in Allegan County, MI. ODEQ did not
further evaluate the contribution from Oklahoma to the receptors in
Brazoria County, TX, Milwaukee County, WI, and Sheboygan County, WI
because the contributions from Oklahoma to these receptors were less
than 1 ppb.
For the two remaining Texas receptors, ODEQ returned to Steps 1 and
2 of the 4-Step interstate transport framework using modeling performed
by the Texas Commission on Environmental Quality (TCEQ). The TCEQ
modeling results are included in the Regional docket for this action
(Docket ID No. EPA-R06-OAR-2021-0801). ODEQ stated that the primary
difference between the EPA modeling and the TCEQ modeling is that the
TCEQ modeling used 2012 as the ``base year'' for assessing interstate
transport of ozone pollution in 2023 whereas the EPA modeling used 2011
as the base year for that assessment. In addition, the ODEQ stated that
TCEQ used a method different from the EPA's method to identify whether
a monitor would have trouble maintaining the 2015 ozone NAAQS (i.e., a
maintenance receptor). To identify maintenance receptors, TCEQ
calculated a ``maintenance future year (fy) DV'' by projecting to 2023
the most recent regulatory DV that contains the base year (i.e., the
2012-2014 DV for a base year of 2012), whereas the EPA's methodology
for identifying maintenance receptors uses the maximum DV, which is the
highest monitored DV from among the three DVs that contain the base
year (i.e., the 2009-2011, 2010-2012 and 2011-2013 DVs for a base year
of 2011).
To assess whether Oklahoma is linked to nonattainment of the 2015
ozone standard at the Denton and Tarrant County sites, ODEQ switched to
using the 2023 average DV projected by TCEQ rather than the EPA's
projected average DVs. The ODEQ noted that the projected 2023 average
DV was 68 ppb for the Denton County site and 66 ppb for the Tarrant
County site based on the TCEQ modeling. ODEQ then claimed that these
results demonstrate that both of these sites are in attainment in 2023.
To assess whether Oklahoma interferes with maintenance of the 2015
ozone standard at these two sites, ODEQ used (1) the Texas method to
calculate a ``maintenance future year DV'' for 2023 and (2) a maximum
DV calculated using the highest of the three base year DVs multiplied
by a relative response factor derived from TCEQ's modeling (i.e., EPA's
method for identifying maintenance receptors but using TCEQ's modeling
rather than EPA's modeling). This assessment is summarized in Table OK-
2.
[[Page 9818]]
Table OK-2--Summary of TCEQ Modeling (2012 Base Period) Used by ODEQ To Assess Maintenance Receptors
----------------------------------------------------------------------------------------------------------------
2023 maximum Maintenance DV
Receptor (site ID, county, state) 2023 average DV (ppb) (EPA (ppb)(TCEQ ODEQ's step 1 and step 2
DV (ppb) method)* method) determination
----------------------------------------------------------------------------------------------------------------
481210034 Denton, TX.................. 68 70.7 65.9 Future DVs project no
attainment or
maintenance problems.
484392003 Tarrant, TX................. 66 69.9 62.4 Future DVs project no
attainment or
maintenance problems.
----------------------------------------------------------------------------------------------------------------
* These values are not based on calculations made by the EPA. ODEQ calculated these values by using the maximum
DV for the 2010-2014 5-year period (i.e., the highest of the DVs in 2012, 2013, and 2014) multiplied by
relative response factor for the receptor obtained from TCEQ's modeling.
ODEQ noted in their assessment that based on the TCEQ modeling and
TCEQ definition of maintenance receptor, it is expected that the Denton
and Tarrant sites will not experience nonattainment or maintenance
problems in 2023. Because ODEQ claimed that the Denton and Tarrant
County sites will not be nonattainment or maintenance receptors in
2023, ODEQ did not analyze potential emissions reductions at Step 3 to
address its contribution to these two sites.
With respect to the remaining receptor at Allegan County, MI, ODEQ
provided an analysis of projected 2023 DVs for this site and
information on emissions trends in Oklahoma to assert that emissions
from Oklahoma do not significantly contribute to nonattainment or
interfere with maintenance of the 2015 ozone NAAQS at the Allegan
County, MI site.
ODEQ noted that (1) the DV for the Allegan County, MI site has had
a substantial reduction in the last 6 years from 84 ppb in 2012 to 73
ppb in 2017, a 1.8 ppb per year decrease, on average and (2) the
Allegan County, MI site is substantially influenced by mobile sources
from the Chicago area and these emissions are expected to be greatly
reduced in the near future, by roughly a 1 ppb per year decrease,
leading to attainment of the 2015 ozone standard. The ODEQ then
calculated a projected 2023 maintenance DV for the Allegan County, MI
site using the EPA's method, but assuming that the base year was 2016
rather than 2011, as in the EPA's modeling or 2012 as in the TCEQ
modeling. The ODEQ noted that the maximum DV in the 2016-centered base
period (i.e., 2014-2016, 2015-2017, and 2016-2018) was 75 ppb at the
Allegan County, Michigan site. The ODEQ then calculated the difference
between the 2011-centered base period maximum DV of 86 ppb and the 2023
projected maximum DV of 71.7 ppb, using data from the EPA's modeling.
The ODEQ calculated a ``ppb per year'' reduction of 1.1917 ppb per
year, based on the 14.3 ppb difference between the 2011-centered and
2023 maximum DVs over the 12 years from 2011 to 2023. Finally, ODEQ
applied the 1.1917 ppb per year value to the 2016-centered maximum DV
of 75 ppb to estimate a 2023 maximum DV of 66.66 ppb.
ODEQ also asserted that the relatively small contribution from
Oklahoma (3% of total upwind state contributions) combined with the
distance between Oklahoma sources and the Allegan County, Michigan
site, warrants a focus on nearby states with greater proportional
contributions as the most prudent approach to addressing interstate
transport of ozone precursors for this receptor.
The ODEQ also provided the anthropogenic NOX and VOC
data of Oklahoma's emissions from EPA's emission trends and modeling to
demonstrate an anticipated substantial reduction of NOX and
VOC from 2011 to 2023: (1) Reductions of NOX from 405,000 to
235,000 tons per year and (2) reductions of VOC from 414,000 to 295,000
tons per year.\76\ ODEQ noted these reductions should result in
considerable reductions in ozone concentrations. The ODEQ stated that
due to the emissions reductions required by rules like CSAPR, the 2016
CSAPR Update, and the regional haze requirements, the NOX
emissions from electric generation in Oklahoma have dropped
significantly during the ozone season from 38,285 tons per year in 2011
to 10,435 tons per year in 2017. ODEQ also stated that changes in the
Southwest Power Pool \77\, building of additional windfarms, and
electric utilities installing solar generation facilities have led to
Oklahoma NOX emissions reductions; and that any additional
NOX reductions from the electric generation section would
require more costly emissions controls. ODEQ concluded that the
existing controls in Oklahoma have resulted in significant decreases in
ozone DVs in Oklahoma and that additional controls would not be cost-
effective. Given their conclusions, ODEQ did not adopt additional
controls to reduce ozone precursor emissions (Step 4).
---------------------------------------------------------------------------
\76\ ODEQ used the EPA's emissions data shared alongside the
October 2018 memorandum, ``state-
sector_annual_emissions_data_1.xlsx'' available at https://www.epa.gov/airmarkets/memo-and-supplemental-information-regarding-interstate-transport-sips-2015-ozone-naaqs.
\77\ The Southwest Power Pool is a regional electric
transmission organization regulated by the Federal Energy Regulatory
Commission whose purpose is promoting efficiency and reliability in
the operation and planning of the electric transmission grid and
ensuring non-discrimination in the provision of electric
transmission services. It manages electric transmission in portions
of fourteen states: Arkansas, Iowa, Kansas, Louisiana, Minnesota,
Missouri, Montana, Nebraska, New Mexico, North Dakota, Oklahoma,
South Dakota, Texas and Wyoming. See 18 CFR 35.34 and https://www.ferc.gov/electric-power-markets.
---------------------------------------------------------------------------
B. EPA Evaluation of the ODEQ SIP Submission
The EPA is proposing to find that ODEQ's October 25, 2018, SIP
submission does not demonstrate that the State's obligations with
respect to prohibiting emissions that contribute significantly to
nonattainment or interfere with maintenance of the 2015 ozone NAAQS in
any other state based on the EPA's evaluation of the SIP submission
using the 4-Step interstate transport framework have been met. The EPA
is therefore proposing to disapprove ODEQ's submission.
1. Evaluation of Information Provided by ODEQ Regarding Steps 1 and 2
As noted earlier, ODEQ first used the information from the EPA's
March 2018 memorandum to identify nonattainment and maintenance
receptors with a contribution from Oklahoma of 0.70 ppb or greater
(i.e., ODEQ identified receptors that would be deemed nonattainment and
maintenance receptors under the EPA's methodology for Steps 1 and 2).
ODEQ then utilized a 1 ppb threshold and elected not to further analyze
any receptors to which it did not contribute greater than 1 ppb.
[[Page 9819]]
ODEQ provided further evaluation of the State's emissions to those
receptors to which Oklahoma contributes greater than 1 ppb (i.e.,
Allegan County, MI, Denton County, TX and Tarrant County, TX).
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, as an alternative to a 1 percent threshold, at
Step 2 of the 4-Step interstate transport framework, for the purposes
of identifying linkages to downwind receptors. However, the EPA's
August 2018 memorandum provided that whether or not a 1 ppb threshold
is appropriate must be based on an evaluation of state-specific
circumstances, and no such evaluation was included in the ODEQ's
submittal. Instead, ODEQ's SIP submission justified the State's use of
a 1 ppb threshold based on the threshold's use in the SILs
Guidance.\78\ ODEQ did not explain the relevance of the SILs Guidance
to Oklahoma's statutory obligation under the interstate transport
provision. The SILs Guidance relates to a different provision of the
CAA regarding implementation of the prevention of significant
deterioration (PSD) permitting program, i.e., a program that applies in
areas that have been designated attainment of the NAAQS, and it is not
applicable to the interstate transport provision, which requires states
to eliminate emissions that contribute significantly or interfere with
maintenance of the NAAQS at known, ongoing, or projected air quality
problem areas in other states. The EPA does not, in this action, agree
that the State has justified its application of the 1 ppb threshold.
---------------------------------------------------------------------------
\78\ See FN 32.
---------------------------------------------------------------------------
Additionally, 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 threshold at
Step 2. (The memorandum also indicated that any higher alternative
threshold, such as 2 ppb, would likely not be appropriate.) However,
the EPA also provided that ``air agencies should consider whether the
recommendations in this guidance are appropriate for each situation.''
Following receipt and review of 49 interstate transport SIP submittals
for the 2015 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. \79\ 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.
---------------------------------------------------------------------------
\79\ ``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 comments on this proposed approval and has not
taken final action with respect to this proposal.
---------------------------------------------------------------------------
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.\80\ The availability of different thresholds at Step 2 has
the potential to result in inconsistent application of interstate
transport 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
interstate transport 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 would 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.
---------------------------------------------------------------------------
\80\ 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.
---------------------------------------------------------------------------
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 memorandum that there was some
similarity in the amount of total upwind contribution captured (on a
nationwide basis) between 1 percent 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; \81\ in EPA 2016v2 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.
---------------------------------------------------------------------------
\81\ See August 2018 memorandum, at page 4.
---------------------------------------------------------------------------
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
[[Page 9820]]
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 memorandum 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 basis for the EPA's proposed
disapproval of ADEQ's SIP submission with respect to the Step 2
analysis is, in the Agency's view, warranted even under the terms of
the August 2018 memorandum. The EPA invites comment on this broader
discussion of issues associated with alternative thresholds at Step 2.
(See Supplementary Information section above for details and docket to
submit comments). Depending on public comments received in relation to
this action and further evaluation of this issue, the EPA may determine
to rescind the 2018 memorandum in the future.
In any case, as discussed in the following subsection, based on the
EPA's most recent modeling, the State is projected to contribute
greater than both the one percent and alternative 1 ppb thresholds at
the Denton County, TX receptor, (Monitor ID. 481210034). Based on the
EPA's modeling results included in the March 2018 memorandum, Oklahoma
was also projected to contribute 1.23 ppb to the Denton County, TX
receptor. (In the EPA 2016v2 modeling the Allegan County, MI and
Tarrant County, TX receptors are not projected to have problems
attaining or maintaining the 2015 ozone NAAQS). Even under ODEQ's own
analysis, the State was linked to receptors with contributions
exceeding 1 ppb. Therefore, based on Oklahoma's 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 is inconsequential to our proposed action on the
state's SIP.
In the remainder of this section, EPA evaluates ODEQ's conclusions
that emissions from Oklahoma do not contribute to nonattainment or
interfere with maintenance at receptors in Tarrant County, TX (Monitor
ID. 484392003) and Denton County, TX (Monitor ID. 481210034). We
evaluate ODEQ's conclusions as to the Allegan, MI (Monitor ID.
260050003) in Section IV.B.3 of this action.
With regard to the Denton County and Tarrant County, TX receptors
cited in ODEQ's submission, ODEQ chose to rely on the TCEQ's modeling
and methodology, instead of the EPA modeling, and trends in ozone DVs
and emissions to conclude that these monitoring sites will be in
attainment by 2023 and will not have a problem maintaining the 2015
ozone NAAQS. As noted in Section IV.A of this action, ODEQ used
modeling results from the TCEQ along with the TCEQ alternative method
for identifying maintenance receptors to claim that using the TCEQ
modeling and methods, the Denton County and Tarrant County monitors
would not have a problem maintaining the NAAQS in 2023. The ODEQ
supplemented that analysis by citing the downward trend in
NOX and VOC emissions in Oklahoma. ODEQ also provided TCEQ
modeling and emissions data for the Dallas-Fort Worth nonattainment
area to show that mobile sources represent the largest emissions
category in this area and that emissions from this sector have declined
since 2005 and are expected to continue to decline in the future. As
described in Table OK-2, ODEQ (1) provided the average 2023 DV for the
Denton County, TX receptor from the TCEQ modeling and (2) used TCEQ
modeling data with a 2012 base year to calculate a 2023 maintenance DV
of 65.9 ppb (using the TCEQ methodology for identifying maintenance
receptors) and a 2023 maximum DV of 70.7 ppb (using the EPA methodology
for identifying maintenance receptors, combined with TCEQ's modeling
results). ODEQ relied on this information, which is based on TCEQ
modeling with a 2012 base year, to conclude that the Denton County, TX
and Tarrant County, TX monitors would not have problems attaining and
maintaining the 2015 ozone NAAQS.
ODEQ's SIP submission (or TCEQ, to the extent that Oklahoma is
merely incorporating and relying on Texas' submission) does not
adequately explain or justify how relying on TCEQ's method for
identifying maintenance receptors reasonably identifies areas that will
have difficulty maintaining the NAAQS. EPA proposes to find that ODEQ
has provided no sound technical basis (either on its own or through
reliance on Texas) for how its chosen methodology gives meaning to the
CAA's instruction that states submit interstate transport SIPs that
prohibit their states' emissions from interfering with the maintenance
of the NAAQS in another state.
In North Carolina v. EPA, 531 F.3d 896, 909-11 (D.C. Cir. 2008),
the D.C. Circuit rejected the EPA's CAIR on the basis that the EPA had
not adequately given meaning to the phrase ``interfere with
maintenance'' in the interstate transport provision. Specifically,
North Carolina argued that it had counties that were projected to
attain the NAAQS in the future analytic year, but were at risk of
falling back into nonattainment due to interference from upwind
sources, particularly given year-to-year variability in ozone levels.
The court agreed, holding that the EPA's rule did not adequately
protect ``[a]reas that find themselves barely meeting attainment.'' Id.
at 910. Consequently, the EPA has developed a methodology, used in its
2011 CSAPR and its 2016 CSAPR Update and Revised CSAPR Update, for
identifying areas that may struggle to maintain the NAAQS. See 76 FR at
48227-28. EPA's approach to addressing maintenance receptors was upheld
in the EME Homer City litigation. See 795 F.3d 118, 136-37. It was also
upheld in Wisconsin. 938 F.3d at 325-26. In Wisconsin, the court noted
that four upwind states were linked only to maintenance receptors and
rejected the argument that application of the same control level as EPA
imposes for those states linked to nonattainment receptors was
unreasonable or unlawful absent a particularized showing of
overcontrol. Id. at 327.
In order to explain the differences between TCEQ's and the EPA's
methodology for identifying maintenance receptors, it is helpful to
provide some additional context of how the EPA projects future air
quality.
The EPA's air quality modeling guidance has long recommended
developing a base DV (i.e., the DV that will be used as a starting
point to model and analyze for purposes of projecting future air
quality concentrations) that is the average of three DVs spanning a
five-year period, centered around one year for which an emissions
inventory will be submitted (e.g., if 2011 was the base emissions
inventory year, a state would use monitored values from 2009-2011,
2010-2012, 2011-2013 as the starting point for projecting air quality
concentrations in future years).\82\ The average of these three DVs is
then multiplied by a relative response factor \83\ to generate an
average DV for the future year.\84\ If a receptor's average
[[Page 9821]]
future year DV is greater than or equal to the level of the NAAQS, and
the receptor has recent monitored data that violates the NAAQS, that
receptor is considered a ``nonattainment'' receptor at Step 1. To
identify maintenance receptors, the EPA's methodology looks to the
highest DV of the three DVs used to calculate the 5-year weighted
average DV (e.g., in the 2011 example, if 2009-2011 had the highest DV
of 2009-2011, 2010-2012, and 2011-2013). The EPA then applies the same
relative response factor to that highest DV to generate a projected
future maximum DV. Where a receptor's maximum DV exceeds the level of
the NAAQS, the EPA has deemed those receptors to be ``maintenance''
receptors. This methodology was designed to address the D.C. Circuit's
holding that the CAA's ``interference with maintenance'' prong requires
states and the EPA to protect areas that may struggle with maintaining
the standard in the face of variable conditions.
---------------------------------------------------------------------------
\82\ See FN 73.
\83\ See FN 53.
\84\ While it is not critical to this discussion, for purposes
of explanation, the relative response factor is a fractional change
that represents how ozone at a given receptor responds to changes in
emissions when all other variables are constant. For more
explanation of the RRF, please see 2018 Air Quality Modeling
Guidance or 2014 Draft Air Quality Modeling Guidance.
---------------------------------------------------------------------------
In its modeling, TCEQ adopted an identical approach to the EPA's
for identifying nonattainment receptors--it looked at three sets of DVs
over a five-year period and averaged those DVs to generate a base year
DV. TCEQ then applied a relative response factor to that base year DV
to project a receptor's average DV in the future year. For maintenance
receptors, however, TCEQ elected not to examine variability in DVs over
a five-year period by using the highest DV of the three DVs making up
the base year DV. Instead, TCEQ (and by extension, ODEQ), used only the
most recent DV of the three DVs, regardless of whether the most recent
DV was highest or lowest. TCEQ's proffered explanation for using the
most recent DV to identify maintenance receptors was that the latest DV
``takes into consideration . . . any emissions reductions that might
have occurred.'' \85\ TCEQ in its submission does not explain why or
how this methodology identifies those areas that may be meeting the
NAAQS or that may be projected to meet the NAAQS but may nevertheless
struggle to maintain the NAAQS, given meteorological variability. In
fact, because TCEQ's stated purpose in using the most recent DV was to
capture more recent emissions reductions, Texas' methodology appears to
be aimed at limiting receptors which could be identified as maintenance
receptors, compared to the EPA's methodology, which was designed to
identify those areas that might struggle to maintain the NAAQS in
particularly ozone conducive conditions.
---------------------------------------------------------------------------
\85\ TCEQ submission at 3-39 to 3-40, available in the Regional
docket for this action (Docket ID No. EPA-R06-OAR-2021-0801).
---------------------------------------------------------------------------
As discussed further in the EPA Region 6 TSD \86\ for this action,
the EPA has reviewed the set of 21 receptors for which Texas had
contributions of 0.7 ppb or more in the EPA's 2016 base year modeling
analyses, or TCEQ's modeling (2012 base year), and evaluated the
results of using TCEQ's alternate maintenance methodology. For these 21
receptors, TCEQ's method resulted in 15 of the 21 2023 maintenance DVs
predicted to be lower than the 2023 nonattainment DVs from the
nonattainment methodology that uses the 5-year center weighted average.
Of these 15 receptors, three receptors have 2023 maintenance DVs that
are 3 ppb lower, five receptors have 2023 maintenance DVs that are 2
ppb lower, and seven receptors have 2023 maintenance DVs that are 1 ppb
lower. In comparison, using the EPA's maintenance methodology results
in all 21 2023 maintenance DVs being equal or up to 4 ppb higher than
the 2023 nonattainment DVs. Again, the EPA uses the average of the
three DVs that contain the base year modeled for the nonattainment
methodology and the maximum of these three DVs for the maintenance
methodology. Because TCEQ's maintenance methodology of just using the
most recent DV (2012-2014 DV) often results in maintenance DVs lower
than the 2023 nonattainment DVs methodology results, the EPA finds that
the TCEQ methodology is not adequately identifying conditions when a
receptor would have more difficulty maintaining the standard. In fact,
the TCEQ's method also identified one receptor in their SIP submission
as a nonattainment receptor in 2023 that would not have been identified
as a maintenance receptor, which further highlights the concern that
TCEQ's method did not adequately identify areas that may struggle to
maintain the standard. TCEQ did not address whether the three years
that comprise the most recent design value (i.e., 2012, 2013, and 2014)
had meteorological conditions highly conducive for formation of high
ozone concentrations and thus would be an appropriate time period to
assess whether area could have difficulty maintaining the standard and
the EPA's analysis confirms that this time period is not highly
conducive to ozone formation, at least for many receptors. The
consequence of TCEQ's maintenance method is that it often results in
lower DVs than the nonattainment method as demonstrated by our
analysis, which indicates that it is often not considering conditions
when an area would have difficulty maintaining the standard. Further,
it is unreasonable to have a method that would not identify
nonattainment receptors also as maintenance receptors.
---------------------------------------------------------------------------
\86\ ``EPA Region 6 2015 8-Hour Ozone Transport SIP Proposal
Technical Support Document'' (EPA Region 6 2015 Ozone Transport SIP
TSD.pdf) included in Docket ID No. EPA-R06-OAR-2021-0801.
---------------------------------------------------------------------------
Again, EPA also assessed a number of monitored DV trends that were
provided in TCEQ's SIP and previous TCEQ attainment demonstration SIPs
indicating that there are at times large annual fluctuations upward
from year to year in monitored DVs (sometimes 2-3 ppb increase in one
year) that are due to variations in meteorology. Neither TCEQ nor ODEQ
addressed in their SIP submissions whether the three years that
comprise the most recent DV (i.e., 2012, 2013, and 2014) had
meteorological conditions conducive for formation of high ozone
concentrations. On the other hand, the EPA methodology can identify
variations in ozone levels that might result in difficulty in
maintaining the standard over a longer period of time. The TCEQ method
will only identify areas that have difficulty maintaining the standard
for a single design value period and, as a result, does not address the
meteorological variability issue sufficiently.
In its SIP submittal, ODEQ contended that, based on TCEQ's use of a
2012 base year, and using TCEQ's air quality modeling, even if Texas
had used the EPA's method of identifying maintenance receptors, the
projected maximum DV for the Denton County and Tarrant County receptors
would be 70.7 ppb and 69.9 ppb, respectively, which are considered to
be in attainment of the 2015 ozone NAAQS in 2023. However, this
conclusion relied upon a relative response factor derived from the TCEQ
modeling and TCEQ's modeling results, which are discussed in more
detail in Section V of this action and in the EPA Region 6 TSD.\87\
TCEQ's modeled projections for 2023 including nonattainment and
maintenance values (using either TCEQ' or EPA's methodology) are much
lower than recent monitored values (2018-2020 DV and preliminary 2019-
2021 DVs) \88\ for
[[Page 9822]]
many monitors and the amount of further DV reductions needed to match
TCEQ's modeling is more than is reasonably expected to occur for many
monitors/receptors. This underestimation of future DVs results in mis-
identifying these two receptors and other receptors as not being
nonattainment or maintenance receptors. Specifically, these two
receptors would need to have at least a 3-4 ppb decrease in the next 2-
3 years just to attain the 2015 Ozone NAAQS in 2023. As discussed in
the EPA Region 6 TSD, TCEQ's previous DFW Attainment Demonstration SIP
includes long-term DV trends analysis that indicates that DFW DVs
decrease approximately 1 ppb per year.\89\ Moreover, as discussed in
Section IV.B.2 of this action, the EPA's updated modeling, which relies
upon more recent data and the latest information on emissions
reductions, indicates that the maximum design value in 2023 for the
Denton County receptor is 72.2 ppb. Recent monitored air quality data
at the Denton receptor are consistent with the EPA's projections that
this is an area that will struggle to maintain the 2015 ozone NAAQS in
2023; the 2020 DV for Denton was 72 ppb.\90\
---------------------------------------------------------------------------
\87\ Id.
\88\ Monitoring data from the EPA's Air Quality System (AQS)
(https://www.epa.gov/aqs). 2021 monitoring data is preliminary and
still has to undergo Quality Assurance/Quality Control analysis and
be certified by the State of Texas, submitted to EPA, and reviewed
and concurred on by EPA. 2018-2020 DVs are 72 ppb and 73 ppb at the
Denton County and Tarrant County monitors/receptors respectively.
Preliminary 2019-2021 DVs are 74 ppb and 72 ppb at the Denton County
and Tarrant County monitors/receptors respectively.
\89\ EPA also analyzed trends using AQS data, See EPA Region 6
TSD.
\90\ DVs 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.
---------------------------------------------------------------------------
Finally, in its submittal, ODEQ pointed to the significant
reductions in emissions that have occurred in the State, but the EPA
believes these reductions have already been accounted for in the most
recent modeling; therefore, even with these reductions, the Denton
County, TX receptor is projected to struggle with maintenance of the
2015 ozone NAAQS in 2023.
2. Results of the EPA's Step 1 and Step 2 Modeling and Findings for
Oklahoma
As described in Section I of this action, the EPA performed air
quality modeling using the 2016v2 platform to project DVs and
contributions for 2023. This data was examined to determine if Oklahoma
contributes at or above the threshold of 1 percent of the 2015 ozone
NAAQS (0.70 ppb) to any downwind nonattainment or maintenance receptor.
As shown in Table OK-3, the most recent modeling data \91\ indicate
that in 2023, emissions from Oklahoma contribute greater than one
percent of the standard to maintenance-only receptors in Denton County,
TX and in Cook County, IL. Oklahoma is not linked to any nonattainment
receptors in EPA's most recent modeling (EPA 2016v2 modeling).
Therefore, based on the EPA's evaluation of the information submitted
by ODEQ and based on the EPA's most recent modeling results for 2023,
the EPA proposes to find that Oklahoma 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.
---------------------------------------------------------------------------
\91\ These modeling results are consistent with the results of a
prior round of 2023 modeling using the 2016v1 emissions platform
which became available to the public in the fall of 2020 in the
Revised CSAPR Update, as noted above. That modeling showed that
Oklahoma had a maximum contribution greater than 0.70 ppb to at
least one nonattainment or maintenance-only receptor in 2023. These
modeling results are included in ``Ozone DVs And Contributions
Revised CSAPR Update.xlsx'' in Docket ID No. EPA-HQ-OAR-2021-0663.
Table OK-3--Projected Nonattainment and Maintenance Receptors With Oklahoma Linkages in 2023 Based on EPA 2016v2
Modeling
----------------------------------------------------------------------------------------------------------------
Oklahoma
Receptor (site ID, county, Nonattainment/ 2020 DV 2023 average 2023 maximum contribution
state) maintenance DV (ppb) DV (ppb) (ppb)
----------------------------------------------------------------------------------------------------------------
481210034, Denton, TX......... Maintenance..... 72 70.4 72.2 1.19
170310032, Cook, IL........... Maintenance..... 74 69.8 72.4 0.75
----------------------------------------------------------------------------------------------------------------
3. Evaluation of Information Provided by ODEQ 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 contribute significantly to nonattainment or interfere
with maintenance and, thus, must be eliminated under CAA section
110(a)(2)(D)(i)(I).
To effectively evaluate 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. at 519. 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. ODEQ did not conduct
such an analysis in their SIP submission.
As noted earlier, ODEQ provided some data on emissions and already
implemented emissions reductions for sources in Oklahoma and stated
that the 2016 CSAPR Update is the only reasonable control warranted
based on Oklahoma's limited contributions to the Michigan and Texas
receptors. Thus, Oklahoma relied on its EGUs being subject to the CSAPR
Update (which reflected a stringency at the nominal marginal cost
threshold of $1400/ton (2011$) for the 2008 ozone NAAQS) to argue that
it had already implemented all cost-effective emissions reductions, and
had no additional statutory
[[Page 9823]]
obligation to prohibit emissions under CAA section 110(a)(2)(D)(i)(I)
with respect to the 2015 ozone NAAQS.
The EPA disagrees with ODEQ's conclusions for the following
reasons: First, the CSAPR Update did not regulate non-electric
generating units, and thus this analysis is incomplete. See Wisconsin,
938 F.3d at 318-20. Second, relying on the CSAPR Update's (or any other
CAA program's) determination of cost-effectiveness without further Step
3 analysis is not approvable. Cost-effectiveness must be assessed in
the context of the specific CAA program; assessing cost-effectiveness
in the context of ozone transport should reflect a more comprehensive
evaluation of the nature of the interstate transport problem, the total
emissions reductions available at several cost thresholds, and the air
quality impacts of the reductions at downwind receptors. While the EPA
has not established a benchmark cost-effectiveness value for 2015 ozone
NAAQS interstate transport obligations, because the 2015 ozone NAAQS is
a more stringent and more protective air quality standard, it is
reasonable to expect control measures or strategies to address
interstate transport under this NAAQS to reflect higher marginal
control costs. As such, the marginal cost threshold of $1,400/ton for
the CSAPR Update (which addresses the 2008 ozone NAAQS and is in 2011$)
is not an appropriate cost threshold and cannot be approved as a
benchmark to use for interstate transport SIP submissions for the 2015
ozone NAAQS.
In addition, the most recent EPA modeling captures all existing
CSAPR trading programs in the baseline, and that modeling confirms that
these control programs were not sufficient to eliminate Oklahoma's
linkage at Steps 1 and 2 under the 2015 ozone NAAQS. The State was
therefore obligated at Step 3 to assess additional control measures
using a multifactor analysis.
Finally, relying on a FIP at Step 3 is per se not approvable if the
state has not adopted that program into its SIP and instead continues
to rely on the FIP. States may not rely on FIP measures to meet SIP
requirements. See CAA section 110(a)(2)(D) (``Each such [SIP] shall . .
. contain adequate provisions . . . .''). See also CAA section
110(a)(2)(A); Committee for a Better Arvin v. U.S. E.P.A., 786 F.3d
1169, 1175-76 (9th Cir. 2015) (holding that measures relied on by state
to meet CAA requirements must be included in the SIP).
In addition, ODEQ's submission included a weight of evidence
evaluation of its contribution to the Allegan County, MI receptor to
conclude that it does not contribute significantly to nonattainment or
maintenance at the receptor.
The EPA disagrees with respect to ODEQ's assertion regarding the
relatively small contribution of emissions from Oklahoma to the Allegan
County, MI receptor compared to emissions from other upwind states such
as Illinois. Whether emissions from other states or countries also
contribute to the same downwind air quality issue is irrelevant in
assessing whether a downwind state has an air quality problem, or
whether an upwind state is contributing significantly to that problem.
States are not obligated under CAA section 110(a)(2)(D)(i)(I) to reduce
emissions sufficient on their own to resolve downwind receptors'
nonattainment or maintenance problems. Rather, states are obligated to
eliminate their own significant contribution or interference with the
ability of other states to attain or maintain the NAAQS.
Further, the court in Wisconsin explained that downwind
jurisdictions often may need to heavily rely on emissions reductions
from upwind states in order to achieve attainment of the NAAQS, 938
F.3d at 316-17; such states would face increased regulatory burdens
including the risk of bumping up to a higher nonattainment
classification if attainment is not reached by the relevant deadline,
Maryland, 958 F.3d at 1204. Indeed, the D.C. Circuit in Wisconsin
specifically rejected petitioner arguments suggesting that upwind
states should be excused from interstate transport obligations on the
basis that some other sources of emissions (whether international or
another upwind state) could be considered the ``but-for'' cause of
downwind air quality problem. 938 F.3dat 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
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 the ``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 upwind states also contribute some
amount of pollution to the same receptors to which the state is linked.
As explained in Section IV.A of this action, ODEQ's weight of
evidence also concluded that the Allegan receptor would be attaining
the NAAQS in 2023 based on an analysis that assumed a projection of a
linear reduction in DVs across a 12-year period (2011 to projected 2023
values), and then applied that annual reduction (1.1917 ppb/year) to
the receptor's 2016-centered base period maximum DV (75 ppb). The EPA
does not necessarily agree that the assumptions made in Oklahoma's
weight-of-evidence analysis are reasonable; however, because the
updated modeling also shows that Allegan County, MI is no longer a
receptor in 2023, we propose to find such assumptions are
inconsequential to our action on Oklahoma's SIP.
We recognize that the results of the EPA (2011 and 2016 base year)
modeling indicated different receptors and linkages at Steps 1 and 2 of
the 4-Step interstate transport framework. These differing results
regarding receptors and linkages can be affected by the varying
meteorology from year to year, but we do not think the differing
results mean that the modeling or the EPA methodology for identifying
receptors or linkages is inherently unreliable. Rather, these separate
modeling runs all indicated: (1) That there are receptors that would
struggle with nonattainment or maintenance in the future; and (2) that
Oklahoma was linked to some set of these receptors, even if the
receptors and linkages differed from one another in their specifics
(e.g., Oklahoma was linked to a different set of receptors in one
modeling run versus another). These results indicate that emissions
from Oklahoma are substantial enough to generate linkages at Steps 1
and 2 to at least some downwind receptors, under varying assumptions
and meteorological conditions, even if the precise set of linkages
changed between modeling runs.
We therefore propose that ODEQ was required to analyze emissions
from the sources and other emissions activity from within the State to
determine
[[Page 9824]]
whether its contributions were significant. Because ODEQ failed to
perform this analysis, we propose to disapprove its submission.
4. Evaluation of Information Provided by ODEQ 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,
ODEQ'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, EPA proposes to disapprove ODEQ's 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).
5. Conclusion
Based on the EPA's evaluation of ODEQ's SIP submission, the EPA is
proposing to find that the portion of ODEQ's 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 which will interfere with maintenance
of the 2015 ozone NAAQS in any other state.
C. Impact on Areas of Indian Country
Following the U.S. Supreme Court decision in McGirt v Oklahoma, 140
S Ct. 2452 (2020), the Governor of the State of Oklahoma requested
approval under Section 10211(a) of the Safe, Accountable, Flexible,
Efficient Transportation Equity Act of 2005: A Legacy for Users, Public
Law 109-59, 119 Stat. 1144, 1937 (August 10, 2005) (``SAFETEA''), to
administer in certain areas of Indian country (as defined at 18 U.S.C.
1151) the State's environmental regulatory programs that were
previously approved by the EPA for areas outside of Indian country. The
State's request excluded certain areas of Indian country further
described below. In addition, the State only sought approval to the
extent that such approval is necessary for the State to administer a
program in light of Oklahoma Dept. of Environmental Quality v. EPA, 740
F.3d 185 (D.C. Cir. 2014).\92\
---------------------------------------------------------------------------
\92\ In ODEQ v. EPA, the D.C. Circuit held that under the CAA, a
state has the authority to implement a SIP in non-reservation areas
of Indian country in the state, where there has been no
demonstration of tribal jurisdiction. Under the D.C. Circuit's
decision, the CAA does not provide authority to states to implement
SIPs in Indian reservations. ODEQ did not, however, substantively
address any request under the separate authority in Indian country
provided specifically to Oklahoma under SAFETEA. That separate
authority was not invoked until the State submitted its request
under SAFETEA, and was not approved until the EPA's decision,
described in this section, on October 1, 2020.
---------------------------------------------------------------------------
On October 1, 2020, the EPA approved Oklahoma's SAFETEA request to
administer all of the State's EPA-approved environmental regulatory
programs, including the Oklahoma SIP, in the requested areas of Indian
country. As requested by Oklahoma, the EPA's approval under SAFETEA
does not include Indian country lands, including rights-of-way running
through the same, that: (1) Qualify as Indian allotments, the Indian
titles to which have not been extinguished, under 18 U.S.C. 1151(c);
(2) are held in trust by the United States on behalf of an individual
Indian or Tribe; or (3) are owned in fee by a Tribe, if the Tribe (a)
acquired that fee title to such land, or an area that included such
land, in accordance with a treaty with the United States to which such
Tribe was a party, and (b) never allotted the land to a member or
citizen of the Tribe.
The EPA's approval under SAFETEA expressly provided that to the
extent the EPA's prior approvals of Oklahoma's environmental programs
excluded Indian country, any such exclusions are superseded for the
geographic areas of Indian country covered by the EPA's approval of
Oklahoma's SAFETEA request.\93\ The approval also provided that future
revisions or amendments to Oklahoma's approved environmental regulatory
programs would extend to the covered areas of Indian country (without
any further need for additional requests under SAFETEA).\94\
---------------------------------------------------------------------------
\93\ The EPA's prior approvals relating to Oklahoma's SIP
frequently noted that the SIP was not approved to apply in areas of
Indian country (consistent with the D.C. Circuit's decision in ODEQ
v. EPA) located in the state. See, e.g., 85 FR 20178, 20180 (April
10, 2020). Such prior expressed limitations are superseded by the
EPA's approval of Oklahoma's SAFETEA request.
\94\ On December 22, 2021, the EPA proposed to withdraw and
reconsider the October 1, 2020 SAFETEA approval. See https://www.epa.gov/ok/proposed-withdrawal-and-reconsideration-and-supporting-information. The EPA is engaging in further consultation
with tribal governments and expects to have discussions with the
State of Oklahoma as part of this reconsideration. The EPA also
notes that the October 1, 2020 approval is the subject of a pending
challenge in Federal court. Pawnee Nation of Oklahoma v Regan, No.
20-9635 (10th Cir.). The EPA may make further changes to the
approval of Oklahoma's program to reflect the outcome of the
proposed withdrawal and reconsideration of the October 1, 2020
SAFETEA approval. To the extent any change occurs in the scope of
Oklahoma's SIP authority in Indian country before the finalization
of this proposed rule, such a change may affect the scope of the
EPA's final action on the proposed rule.
---------------------------------------------------------------------------
As explained earlier, the EPA is proposing to find that the portion
of Oklahoma's 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 which
will contribute significantly to nonattainment or interfere with
maintenance of the 2015 ozone NAAQS in any other state. Consistent with
the D.C. Circuit's decision in ODEQ v. EPA and the EPA's October 1,
2020, SAFETEA approval, this disapproval if finalized as proposed will
extend to areas of Indian country in Oklahoma where the State has SIP
planning authority.
V. Texas SIP Submission Addressing Interstate Transport of Air
Pollution for the 2015 Ozone NAAQS and the EPA Evaluation of the SIP
Submission
A. Summary of TCEQ SIP Submission Addressing Interstate Transport of
Air Pollution for the 2015 Ozone NAAQS
On August 17, 2018, the Texas Commission on Environmental Quality
(TCEQ) made a SIP submission addressing interstate transport of air
pollution for the 2015 ozone NAAQS. The SIP submission provided TCEQ's
analysis of their impact to downwind states using a framework similar
to EPA's 4-Step framework and concluded that emissions from Texas will
not contribute significantly to nonattainment or interfere with
maintenance of the 2015 ozone NAAQS in other states.
In the submittal, TCEQ provided the steps they used to assess
whether emissions from Texas contribute significantly to nonattainment
or interfere with maintenance of the 2015 ozone NAAQS in other States:
(1) Identify monitors projected to be in nonattainment or have
maintenance issues in future year 2023; (2) identify for further review
projected nonattainment and/or maintenance monitors in other states
that are impacted by emissions from Texas; and (3) determine if
emissions from Texas contribute significantly to nonattainment or
interfere with maintenance at the monitors identified in TCEQ Step 2.
TCEQ stated that their Step 1 is the same as EPA's Step 1 and that
their Steps 2 and 3 are equivalent to EPA's Step 2. TCEQ used a
[[Page 9825]]
contribution threshold of one percent of the NAAQS (0.7 ppb) in their
Step 2 analysis to identify nonattainmentand/or maintenance monitors in
other states that are impacted by emissions from Texas. TCEQ further
stated that EPA's Steps 3 and 4 are relevant only if emissions from
Texas contribute significantly to nonattainment or interfere with
maintenance at downwind monitors in another state. Because Texas TCEQ
concluded that it has no such emissions, EPA's Steps 3 and 4 are not
addressed in the SIP submission.
To identify monitors projected to be in nonattainment or have
maintenance issues in 2023, (EPA Step 1 and TCEQ Step 1), TCEQ
conducted its own regional photochemical modeling using a 2012 base
year. TCEQ's modeling and EPA's modeling differ in significant
respects, which are discussed in detail in the EPA Region 6 2015 8-Hour
Ozone Transport SIP Proposal Technical Support Document (EPA Region 6
TSD).\95\ In particular, TCEQ used a 2012 base year, stating that (1)
the year 2012 had above average temperatures across most of the U.S.,
except in some states in the southeast and (2) the year 2011, (which
was used by the EPA in the NODA published on January 6, 2017 and the
October 2017 updated modeling data for 2023),\96\ was a
meteorologically anomalous year for Texas and surrounding states as it
was the hottest year on record and the single-worst drought year
recorded in Texas since 1895. TCEQ's modeling also used some different
emissions estimates for the base year and future year 2023 emissions,
including different future year emissions for EGUs. There were also
some differences in methods used in the model results analysis and the
model performance evaluation. TCEQ also used a different methodology
than the EPA to identify monitors projected to be maintenance receptors
in 2023. TCEQ used only the most recent DV containing the base year
2012, (i.e., the monitored DV for 2012-2014), to project a 2023
``maintenance DV'' for assessing whether a monitor would have
maintenance issues. The EPA's methodology uses the maximum of the three
consecutive regulatory DVs containing the base year, which is the
highest monitored DV from among the three DVs that contain the 2011
base year (i.e., the 2009-2011 DV, 2010-2012 DV or and 2011-2013 DV
that all contain modeled base year of 2011), to project a 2023 maximum
DV for assessing whether a monitor would have maintenance issues. Texas
explained that it chose to define maintenance receptors in this way to
capture more recent emission reductions. The SIP submittal also
included a discussion of why TCEQ believes their approach for
identifying maintenance receptors is appropriate. The TCEQ modeling and
differences with the EPA modeling is discussed in detail in the EPA
Region 6 TSD for this action.
---------------------------------------------------------------------------
\95\ ``EPA Region 6 2015 8-Hour Ozone Transport SIP Proposal
Technical Support Document'' (EPA Region 6 2015 Ozone Transport SIP
TSD.pdf) included in Docket ID No. EPA-R06-OAR-2021-0801.
\96\ The NODA and the October 2017 modeling are discussed in
Section I.C of this action.
---------------------------------------------------------------------------
Based on their modeling, TCEQ provided: (1) A table of downwind
receptors projected to be in nonattainment of the 2015 ozone NAAQS in
2023 and have a contribution from Texas emissions at a threshold of 0.7
ppb or greater and (2) a table of downwind maintenance receptors
projected to have problems attaining and maintaining the 2015 ozone
NAAQS in 2023 and have a contribution from Texas emissions at a
threshold of 0.7 ppb or greater. TCEQ identified these receptors for
further analysis. The nonattainment and maintenance receptors provided
by TCEQ are listed in Table TX-1. TCEQ noted that except for Arapahoe
County, CO (Monitor ID. 80050002) all the maintenance receptors are
also nonattainment receptors.
Table TX-1--Projected 2023 Nonattainment and Maintenance Receptors Identified by TCEQ Modeling Using 2012 Base
Year
----------------------------------------------------------------------------------------------------------------
2023
2023 average maintenance DV Texas
Receptor (site ID, county, state) DV (ppb) (ppb) (TCEQ contribution
method) (ppb)
----------------------------------------------------------------------------------------------------------------
80350004, Douglas, CO........................................... 73 72 1.42
80590006, Jefferson, CO......................................... 72 73 1.26
80590011, Jefferson, CO......................................... 71 71 1.26
80690011, Larimer, CO........................................... 72 71 1.22
80050002, Arapahoe, CO.......................................... *70 71 1.15
40038001, Cochise, AZ........................................... 71 **69 1.06
60371201, Los Angeles, CA....................................... 80 78 0.76
60371701, Los Angeles, CA....................................... 80 82 0.72
60376012, Los Angeles, CA....................................... 87 86 0.9
60658001, Riverside, CA......................................... 88 85 0.73
60658005, Riverside, CA......................................... 84 83 0.71
60710001, San Bernardino, CA.................................... 71 72 0.84
60710306, San Bernardino, CA.................................... 76 77 0.81
60711004, San Bernardino, CA.................................... 91 90 0.88
60714001, San Bernardino, CA.................................... 82 79 0.86
60714003, San Bernardino, CA.................................... 94 91 0.74
----------------------------------------------------------------------------------------------------------------
* TCEQ did not include this value in their SIP narrative (this cell was blank). The EPA obtained this value from
data that was in TCEQ's spreadsheet of future 2023 DVs with state contributions.
** TCEQ did not provide this calculation. The EPA used TCEQ's modeling information to calculate this value using
the Relative Response Factor in TCEQ spreadsheet of future 2023 DVs with state contributions and the monitor's
2012-2014 DV (0.983 X 71 ppb, truncation applied).
TCEQ also noted that in the EPA's 2017 Transport NODA, the EPA's
modeling linked Texas to six receptors based on the receptors being
identified as nonattainment or maintenance receptors and based on a 0.7
ppb contribution threshold. TCEQ provided a table of those monitors
along with the EPA and TCEQ modeling results for
[[Page 9826]]
those receptors (Table TX-2).\97\ TCEQ stated that the differences are
due to changes the TCEQ made to modeling inputs (primarily the
different base year of 2012 versus the EPA's 2011), analysis, and
methodologies (primarily TCEQ's alternate maintenance receptor
methodology), see the EPA Region 6 TSD included in the Regional docket
for this action (Docket ID No. EPA-R06-OAR-2021-0801) for more details.
With exception of the Jefferson County, CO receptor (Monitor ID.
80590011) TCEQ did not further review its linkages to any of the
receptors in Table TX-2.
---------------------------------------------------------------------------
\97\ TCEQ SIP Submission, at page 3-49 (Table 3-12).
Table TX-2--TCEQ Information on Receptors Linked to Texas by EPA Modeling in the Transport NODA Published on
January 6, 2017
----------------------------------------------------------------------------------------------------------------
EPA 2023 EPA Texas TCEQ 2023 TCEQ Texas
Receptor (site ID, county, state) average DV contribution average DV contribution
(ppb) (ppb) (ppb) (ppb)
----------------------------------------------------------------------------------------------------------------
260050003, Allegan, MI.......................... 68.8 2.49 71 0.59
551170006, Sheboygan, WI........................ 71.0 1.92 70 0.73
240251001, Harford, MD.......................... 71.3 0.91 65 0.69
360850067, Richmond, NY......................... 71.2 0.77 62 0.67
361030002, Suffolk, NY.......................... 71.3 0.71 67 0.63
80590011, Jefferson, CO......................... 69.7 1.03 71 1.26
----------------------------------------------------------------------------------------------------------------
TCEQ then used a weight of evidence approach to assess whether
emissions from Texas contribute significantly to nonattainment or
interfere with maintenance at the receptors listed in Table TX-1. TCEQ
stated that the Texas contribution to a receptor should be deemed
``significant'' only if there is a persistent and consistent pattern of
contribution on several days with elevated ozone. Consideration was
given to factors such as DV trends, number of elevated ozone days, back
trajectory analysis on elevated ozone days, modeled concentrations on
future expected elevated ozone days, total interstate contributions at
tagged monitors, and responsiveness of ozone to emissions from Texas.
Based on their assessment, TCEQ concluded that emissions from Texas do
not contribute significantly to nonattainment or interfere with
maintenance of the 2015 ozone NAAQS at any downwind monitors. Our
evaluation of the TCEQ submission is further discussed in Section V.B
and in the EPA Region 6 TSD for this action.
B. EPA Evaluation of the TCEQ SIP Submission
Based on the EPA's evaluation of the SIP submission, the EPA is
proposing to find that TCEQ's August 17, 2018, SIP submission does not
meet the State's obligations with respect to prohibiting emissions that
contribute significantly to nonattainment or interfere with maintenance
of the 2015 ozone NAAQS in any other state.
1. Evaluation of Information Provided by TCEQ Regarding Step 1
As explained in Section I of this action, at Step 1 of the 4-Step
interstate transport framework, the EPA identifies monitoring sites
that are projected to have problems attaining and/or maintaining the
NAAQS (i.e., nonattainment and maintenance receptors). In executing
this step, TCEQ elected to rely on their own modeling and methodology
for identifying receptors. The EPA is evaluating the TCEQ's modeling
and methodology here at Step 1.
i. Evaluation of TCEQ's Methodology for Identifying Maintenance
Receptors
As discussed in Section V.A of this action, in addition to the use
of an alternative modeling platform, TCEQ also created its own method
for identifying maintenance receptors. TCEQ has not adequately
explained or justified how its method for identifying maintenance
receptors reasonably identifies areas that will have difficulty
maintaining the NAAQS. The EPA proposes to find that TCEQ has not
provided a sufficient technical basis for how its chosen methodology
gives meaning to the CAA's instruction that states submit good neighbor
SIPs that prohibit their states' emissions from interfering with the
maintenance of the NAAQS in another state.
In North Carolina v. EPA, 531 F.3d 896, 909-11 (D.C. Cir. 2008),
the D.C. Circuit rejected the EPA's CAIR on the basis that the EPA had
not adequately given meaning to the phrase ``interfere with
maintenance'' in the good neighbor provision. Specifically, North
Carolina argued that it had counties that were projected to attain the
NAAQS in the future analytic year but were at risk of falling back into
nonattainment due to interference from upwind sources, particularly
given year-to-year variability in ozone levels. The court agreed,
holding that the EPA's rule did not adequately protect ``[a]reas that
find themselves barely meeting attainment.'' Id. at 910. Consequently,
the EPA has developed a methodology, as described elsewhere in this
action and used in its 2011 CSAPR and its 2016 CSAPR Update and Revised
CSAPR Update, for identifying areas that may struggle to maintain the
NAAQS. See 76 FR at 48227-28. The EPA's approach to addressing
maintenance receptors was upheld in the EME Homer City litigation. See
795 F.3d 118, 136-37. It was also upheld in Wisconsin. 938 F.3d at 325-
26. In Wisconsin, the court noted that four upwind states were linked
only to maintenance receptors and rejected the argument that
application of the same control level as the EPA imposes for those
states linked to nonattainment receptors was unreasonable or unlawful
absent a particularized showing of overcontrol. Id. at 327.
To explain the differences between TCEQ's and the EPA's methodology
for identifying maintenance receptors, it is helpful to provide some
additional context of how the EPA projects future air quality. The
EPA's air quality modeling guidance has long recommended developing a
base design value (DV) \98\ (i.e., the design value that will be used
as a starting point to model and analyze for purposes of projecting
future air quality concentrations) that is the average of three DVs
spanning a five-year period, centered around one year for which an
emissions inventory will be submitted (e.g., if 2011 was the base
emissions inventory year, a state would use monitored values from 2009-
2011, 2010-2012, 2011-2013 as the starting point for projecting air
quality concentrations in future years).\99\ The
[[Page 9827]]
average of these three DVs is then multiplied by a relative response
factor (RRF) \100\ to generate an average DV for the future year. If a
receptor's average future year DV is greater than or equal to the level
of the NAAQS, and the receptor has recent monitored data that violates
the NAAQS, that receptor is considered a ``nonattainment'' receptor at
Step 1. To identify maintenance receptors, the EPA's methodology looks
to the highest DV of the three DVs used to calculate the 5-year
weighted average design value (e.g., in the 2011 example, if 2009-2011
had the highest design value of 2009-2011, 2010-2012, and 2011-2013).
The EPA then applies the same relative response factor to that highest
design value to generate a projected future maximum design value. Where
a receptor's maximum design value exceeds the level of the NAAQS, the
EPA has deemed those receptors to be ``maintenance'' receptors. This
methodology was designed to address the D.C. Circuit's holding that the
CAA's ``interference with maintenance'' prong requires states and the
EPA to protect areas that may struggle with maintaining the standard in
the face of inter-annual variability in ozone-conducive conditions.
---------------------------------------------------------------------------
\98\ See FN 8.
\99\ See FN 73.
\100\ See FN 53.
---------------------------------------------------------------------------
In its modeling, TCEQ adopted an identical approach to the EPA's
for identifying nonattainment receptors--it looked at three sets of DVs
over a five-year period and averaged those DVs to generate a base year
DV. TCEQ then applied a relative response factor to that base year
design value to project a receptor's average design value in the future
year. For its maintenance receptors, however, TCEQ used only the most
recent design value of the set of three DVs, regardless of whether the
most recent design value was highest or lowest, instead of considering
variability in conditions over a five-year period, or using the highest
DV of the three DVs making up the base year design value. TCEQ's
proffered explanation for using the most recent DV to identify
maintenance receptors was that the latest DV ``takes into consideration
. . . any emissions reductions that might have occurred.'' \101\
However, TCEQ in its submission does not explain how this methodology
takes into account meteorological variability in identifying those
areas that may be meeting the NAAQS or that may be projected to meet
the NAAQS but may nevertheless struggle to maintain the NAAQS.
---------------------------------------------------------------------------
\101\ TCEQ SIP submission at 3-39 to 3-40.
---------------------------------------------------------------------------
TCEQ argued that the 3-year DV used includes some meteorological
variability. Unfortunately, the three years of variation that TCEQ
accounted for is already built into the structure of the standard.
Thus, the TCEQ method gave no consideration to the variability between
calculated DVs which provides a direct indication of the difficulty a
receptor will have in maintaining the standard. In other words, to
determine whether a receptor will have difficulty maintaining the
standard, one must consider the variation in the metric that will be
used to determine compliance with the standard. An indication of the
variability of a metric cannot be determined by only considering a
single estimate of that metric.
TCEQ's stated purpose in using the most recent DV was to capture
more recent emissions reductions. TCEQ's methodology, however, limits
receptors which could be identified as maintenance receptors, compared
to the EPA's methodology largely because it only looks at one design
value period rather than selecting the maximum of the three DV periods
EPA's methodology considers. Thus, TCEQ's methodology greatly reduces
the probability that meteorological conditions which make it difficult
to maintain the standard will be considered. As discussed further
below, the effects of emissions trends are already captured through
other aspects of the methodology to identify receptors. So, in trying
to give more weight to emission reductions, by selecting only one
design value (2012-2014) for its base year, TCEQ's methodology did not
give any consideration to interannual variability in ozone-conducive
meteorology as does the EPA's method.
The EPA's methodology, using the maximum DV which accounts for the
variability in ozone concentrations and DVs due to changes in
meteorology over the five years of the base year DV period, was
designed to identify those areas that might struggle to maintain the
NAAQS in particularly ozone conducive conditions. TCEQ claimed that the
EPA's method undervalues changes in air quality due to emission
reductions and overvalues changes due to variation in meteorology. TCEQ
pointed out that emissions nationwide are generally trending downward
as a result of Federal motor vehicle standards and other technological
improvements. The EPA agrees that ozone levels generally trend
downward, but there is not a steady decline from year to year in ozone
concentrations. Rather, ozone levels tend to vary from year to year
with some years showing an increase instead of a decrease mainly due to
inter-annual variability in ozone-conducive meteorology.\102\ The
variation of DVs at individual monitors from year to year can be
significant, even where emissions trend downwards. The EPA also
assessed a number of monitored DV trends that were provided in TCEQ's
SIP submission and previous TCEQ attainment demonstration SIPs
indicating that there are at times large annual fluctuations upward
from year to year in monitored DVs (sometimes 2-3 ppb increase in one
year) that are due to variations in meteorology.\103\ This is precisely
why it is important to consider highly variable meteorology and its
influence on DVs--the issue at the heart of the D.C. Circuit's finding
on ``interference with maintenance'' in North Carolina. Areas that are
required under the Act to attain by an attainment date may fail to
attain because of a combination of both local emissions, upwind
emissions, and ozone conducive meteorology, among other factors. The
North Carolina decision made clear that in interpreting the good
neighbor provision, upwind state and the EPA obligations to reduce
emissions must account for variable conditions that could cause an area
that is sometimes attaining the NAAQS to fall out of attainment. See
also Wisconsin, 938 F.3d at 327 (``Variations in atmospheric conditions
and weather patterns can bring maintenance receptors into nonattainment
even without elevated emissions.'').
---------------------------------------------------------------------------
\102\ See EPA Region 6 TSD, included in Docket ID No. EPA-R06-
OAR-2021-0801.
\103\ Id.
---------------------------------------------------------------------------
In addition, TCEQ claimed that its use of the 2012-2014 DV (i.e.,
the most recent in the 5-year base period it examined) is more reliable
than the EPA's method, because that more recent DV accounts for both
emission reductions and because there is a shorter interval between the
monitored DV and the projected DV. As we note elsewhere, the TCEQ's
base year modeled inventory is 2012 emissions and the TCEQ's model
projections for 2023 include the expected emission reductions from 2012
thru 2014 and to 2023. By just using the 2012-2014 DV data, TCEQ
claimed they are giving weight to emission reductions during the final
base years where EPA's method does not. The effect of emission
reductions, however, is already factored in the method since the
modeling projection to 2023 is explicitly designed to project the
changes in ozone due to emission reductions from the 2012 base year
emission levels. So, in fact, the EPA method does give weight to
emission reductions. Furthermore, since
[[Page 9828]]
TCEQ agrees that the average of the DVs based on 2010-2014 ozone levels
are reliable enough to use in the identification of nonattainment
receptors, it is unclear how the 2012-2014 period is deemed more
reliable for the maintenance test since the modeled emissions are still
for 2012. We also note, as discussed throughout this action, the EPA
has updated its modeling to use a 2016 base year--that is, a five year
period spanning 2014-2018, and applied its methodology for defining
maintenance receptors using that five year base period. Using a more
recent base period (EPA's 2016v2) provides the most recent design
values, shorter period of projection (2016 to 2023 versus a 2011 or
2012 base year) and a more accurate basis for projections of future air
quality. We note that the EPA undertook a large collaborative multi-
year effort with states (including TCEQ) and other stakeholders input
and review in developing the 2016v2 emission inventories. By virtue of
this update, any monitored DV used by the EPA to identify maintenance
receptors in this action accounts for more recent emission reductions
and provides a shorter interval between base year monitored DV and the
projected future analytic year.
As discussed further in the EPA Region 6 TSD \104\ for this action,
the EPA has reviewed the set of 21 receptors for which Texas had
contributions of 0.7 ppb or more in the EPA's 2016 base year modeling
analyses, or TCEQ's modeling (2012 base year), and evaluated the
results of using TCEQ's alternate maintenance methodology. For these 21
receptors, TCEQ's method resulted in 15 of the 21 2023 maintenance DVs
predicted to be lower than the 2023 nonattainment DVs from the
nonattainment methodology that uses the 5-year center weighted average.
Of these 15 receptors, three receptors have 2023 maintenance DVs that
are 3 ppb lower, five receptors have 2023 maintenance DVs that are 2
ppb lower, and seven receptors have 2023 maintenance DVs that are 1 ppb
lower. In comparison, using the EPA's maintenance methodology results
in all 21 2023 maintenance DVs being equal or up to 4 ppb higher than
the 2023 nonattainment DVs. Again, the EPA uses the average of the
three DVs that contain the base year modeled for the nonattainment
methodology and the maximum of these three DVs for the maintenance
methodology. Because TCEQ's maintenance methodology of just using the
most recent DV (2012-2014 DV) often results in maintenance DVs lower
than the 2023 nonattainment DVs methodology results, the EPA finds that
the TCEQ methodology is not adequately identifying conditions when a
receptor would have more difficulty maintaining the standard. In fact,
the TCEQ's method also identified one receptor in their SIP submission
as a nonattainment receptor in 2023 that would not have been identified
as a maintenance receptor, which further highlights the concern that
TCEQ's method did not adequately identify areas that may struggle to
maintain the standard. TCEQ did not address whether the three years
that comprise the most recent design value (i.e., 2012, 2013, and 2014)
had meteorological conditions highly conducive for formation of high
ozone concentrations and thus would be an appropriate time period to
assess whether area could have difficulty maintaining the standard and
the EPA's analysis confirms that this time period is not highly
conducive to ozone formation, at least for many receptors. The
consequence of TCEQ's maintenance method is that it often results in
lower DVs than the nonattainment test as demonstrated by our analysis,
which indicates that it is often not considering conditions when an
area would have difficulty maintaining the standard. It is also
unreasonable to have a test that would not identify nonattainment
receptors also as maintenance receptors.
---------------------------------------------------------------------------
\104\ ``EPA Region 6 2015 8-Hour Ozone Transport SIP Proposal
Technical Support Document'' (EPA Region 6 2015 Ozone Transport SIP
TSD.pdf) included in Docket ID No. EPA-R06-OAR-2021-0801.
---------------------------------------------------------------------------
TCEQ also made several additional assertions in support of their
conclusion that their method for identifying maintenance receptors was
the better reading of the CAA, compared to the EPA's. TCEQ claimed that
its approach was more consistent with the CAA's concept of maintenance
as areas that were formerly nonattainment and that have since attained
and will continue to maintain by accounting for: (1) Emissions
reductions occurring in the later design values of the base DV period;
(2) ``commitments regarding contingency measures to address future
emission reductions;'' and (3) the impact of any maintenance plans that
are in place. TCEQ also asserted that the EPA's approach conflates the
likelihood of attaining the standard in a future year and the ability
of an attainment monitor to maintain that attainment status.
Specifically, TCEQ argued that because any remedies devised to address
nonattainment monitors would have to apply to maintenance monitors, a
practical consequence of the EPA's approach is that it could lead to
over-control and that it might require upwind states to consider or
implement controls when the downwind state in which the monitor is
located does not have any obligations to control local emissions. TCEQ
argued that this ``conflation'' of nonattainment and maintenance
results in there being no independent meaning to ``maintenance.''
With respect to the first of these assertions from TCEQ, we note
that TCEQ's methodology for identifying receptors (like the EPA's) is
entirely distinct from ozone designations under the Clean Air Act;
neither TCEQ nor the EPA take current or presumed future designations
of areas into account, and any implementation requirements like a
maintenance plan under CAA section 175A, in identifying receptors.
TCEQ's' discussion, therefore, of maintenance plan contingency measures
or maintenance plans generally is irrelevant and misplaced. None of the
areas to which Texas is linked in the EPA 2016v2 modeling has been
redesignated to attainment for the 2015 ozone NAAQS, and none of the
areas to which Texas is linked in its own modeling has been
redesignated to attainment for that NAAQS. We also fail to see how
TCEQ's approach to identifying maintenance receptors differs in any
relevant respect from the EPA's approach with regard to the alleged
``conflation'' of projecting attainment in a future year rather than
the ability of an attainment receptor to maintain attainment. Both TCEQ
and the EPA identify maintenance receptors based on projections of air
quality in a future year to determine whether the receptor will have
difficulty attaining or maintaining the standard. TCEQ's arguments
about overcontrol based on the application of a uniform remedy to
states linked to both nonattainment and maintenance receptors were also
not germane; in this case, TCEQ had identified no remedy to apply
whatsoever because it had failed to identify that the emissions from
Texas cause a problem in the first instance. The D.C. Circuit has
already rejected the idea that the application of a uniform control to
both nonattainment and maintenance receptors is on its face overcontrol
or impermissible under the interstate transport provision. See
Wisconsin, 938 F.3d at 327. Based on our evaluation of TCEQ's approach
to identify maintenance receptors for 2023, we propose to find the
State's approach is inadequate as it does not sufficiently identify
maintenance receptors. Further, TCEQ had not explained how its
[[Page 9829]]
approach meets the statutory requirement to address areas that, even if
meeting the NAAQS, may struggle to maintain the standard in years where
conditions are conducive to ozone formation. Rather, the TCEQ had
created its own approach to identify these areas that they describe as
designed to account for the most emission reductions possible--i.e.,
the most recent DV of the three under analysis; an approach that likely
under-identifies areas that will struggle to maintain the NAAQS and
that certainly is not designed to capture potential air quality
problems.
ii. Evaluation of the TCEQ Modeling
As discussed in Section V.A of this action, TCEQ conducted regional
photochemical modeling to identify nonattainment and maintenance
receptors in 2023 using a 2012 base year. As discussed further in the
EPA Region 6 TSD, we have several concerns with the reliability of
TCEQ's modeling results. States are free to develop their own modeling,
but that modeling must be technically supportable, and the EPA is
obligated to assess and evaluate the reliability of that technical
demonstration when determining whether the Act's requirements are met.
The TCEQ's modeling underestimates future ozone levels. When the
TCEQ 2023 projected concentrations are compared to 2020 and preliminary
2021 monitor values, it is clear that the TCEQ modeling is projecting
an unusual decline in ozone levels without there being an unusual level
of emission reductions to support the decline. The EPA compared recent
monitoring values and reasonably anticipated decreases in DVs by 2023
both within Texas and in other parts of the country. These
underestimations likely result in TCEQ's modeling not adequately
identifying nonattainment and/or maintenance receptors in 2023. These
underestimations also result in smaller projected contributions from
Texas emissions to downwind states. See EPA Region 6 TSD for full
analysis details.
One analysis included in the EPA Region 6 TSD examined the average
amount of improvement that would have to occur for the 9 monitors with
the highest measured design values in the Dallas-Ft. Worth and Houston-
Galveston-Brazoria nonattainment areas (those with an observed 2018-
2020 DV of 74 ppb or greater) to reach the level of ozone projected by
the TCEQ modeling. The average decrease needed by 2023 to meet TCEQ's
2023 projected DVs is 7.56 ppb. Improvements of this magnitude do not
occur in three years unless there is an unusually large change in
emissions or a large change in meteorological conduciveness for ozone
generation. TCEQ did not identify any large emission reductions not
already accounted for in the modeling to be implemented in the 2021-
2023 timeframe nor is the EPA aware of such a change. This information
supports our finding that that TCEQ's modeling is underestimating
future ozone levels in the two nonattainment areas in Texas that make
up a large proportion of the total ozone and a large portion of
emissions of ozone pre-cursors that transport to downwind areas. This
underestimation of future year ozone levels from Texas emissions can
cause both an underestimation of ozone in downwind areas and also an
underestimation of Texas's impact on downwind State's ozone
nonattainment and maintenance receptors.
TCEQ's modeling also underestimates 2023 ozone levels outside of
the State of Texas including areas of interest in California, Colorado
and the Midwest Region (Illinois, Wisconsin, and Michigan). The EPA
discusses this underprediction for all of these areas in the EPA Region
6 TSD. In Table TX-3, we present only the results for the Midwest
Region along with the EPA's modeling prediction. We note that TCEQ's
2023 modeled DVs are significantly lower than the EPA's 2023 modeled
DVs. The table also provides recent monitored 2020 DVs and preliminary
2021 DVs, which shows that recent monitored ozone concentrations are
significantly higher than TCEQ's modeling projected for 2023. TCEQ's
ozone DVs for these receptors would need to drop on the order of 7-15
ppb in two to three years for TCEQ's projections to bear out. As noted
previously, this would require an unusual amount of emission reductions
without any control measures identified of sufficient magnitude. We
note that the EPA's projected 2023 ozone DVs based on EPA 2016v2
modeling show ozone DVs that are also lower than recent monitoring
data. However, EPA 2016v2 modeling projections are much closer to
anticipated 2023 ozone levels as compared to TCEQ's modeling. This
indicates that the EPA's modeling is more accurate in identifying
nonattainment and/or maintenance receptors in the Midwest Region. While
the TCEQ modeling projects much lower overall ozone levels for the
Midwest Region in 2023, the modeling does tend to corroborate the
projected amount emissions that Texas may be contributing to projected
ozone levels at 5 of the 7 nonattainment and maintenance receptors
identified in the EPA's modeling.\105\ Thus, despite the differences in
identification of nonattainment and maintenance receptors, both sets of
modeling indicate that Texas's contribution to receptors in the Midwest
Region are greater than 0.7 ppb (i.e., 1 percent of the 2015 ozone
NAAQS). Table TX-3 provides information on those receptors, including
the amount of contribution attributed to emissions from Texas based on
EPA's 2016v2 modeling and TCEQ's modeling. Despite the differences in
identification of nonattainment and maintenance receptors, both sets of
modeling indicate that Texas's contribution to receptors in the Midwest
are greater than 0.7 ppb (i.e., 1 percent of the 2015 ozone NAAQS).
---------------------------------------------------------------------------
\105\ We note that for two of the Wisconsin receptors, TCEQ's
modeling does not provide information to generate 2023 DVs, so only
5 of the 7 monitors can be compared.
Table TX-3--EPA and TCEQ Modeling Results for Downwind Receptors Identified by EPA 2016v2 Modeling
--------------------------------------------------------------------------------------------------------------------------------------------------------
Monitored 2018-
2023 nonattainment/ EPA: 2023 2020 DV/ EPA: Texas
Receptor (site ID, county, state) maintenance (EPA average DV/ TCEQ: 2023 average DV/ preliminary contribution TCEQ: Texas
2016v2) maximum DV maintenance DV (ppb)* 2019-2021 DV** (ppb) contribution (ppb)
(ppb) (ppb)
--------------------------------------------------------------------------------------------------------------------------------------------------------
170310001, Cook, IL................ Maintenance.......... 69.6/73.4 60/58................ 75/71 0.86 1.6.
170310032, Cook, IL................ Maintenance.......... 69.8/72.4 68/66................ 74/75 1.46 1.31.
170314201, Cook, IL................ Maintenance.......... 69.9/73.4 64/62................ 77/74 1.15 1.25.
170317002, Cook, IL................ Maintenance.......... 70.1/73.0 66/65................ 75/73 1.58 1.22.
[[Page 9830]]
550590019, Kenosha, WI............. Nonattainment........ 72.8/73.7 67/66................ 74/74 1.72 1.44.
550590025, Kenosha, WI............. Maintenance.......... 69.2/72.3 No data***........... 74/72 1.81 No data.***
551010020, Racine, WI.............. Nonattainment........ 71.3/73.2 No data***........... 73/73 1.34 No data.***
--------------------------------------------------------------------------------------------------------------------------------------------------------
* TCEQ did not provide sufficient data and analysis of the meteorology for the 2010-2014 period to support their claim that 2012-2014 period was a worst-
case combination of meteorology compared to the 2010-2012 and 2011-2013 periods. If the future DV projected from this highest value is below the
standard, one can be reasonably certain the receptor will not have difficulty maintaining the standard and, as such, upwind states will not interfere
with maintenance in downwind states. Because the TCEQ method only looks at one DV and does not account for the variability in DVs due to
meteorological conditions, it is less likely to identify maintenance receptors than the EPA method. See https://www.epa.gov/air-trends/air-quality-design-values
** Preliminary 2019-2021 DVs. Monitoring data from the EPA's Air Quality System (AQS) (https://www.epa.gov/aqs). 2021 monitoring data is preliminary and
still has to undergo Quality Assurance/Quality Control analysis and be certified by the State of Texas, submitted to the EPA, and reviewed and
concurred on by EPA. 2018-2020 DVs are 72 ppb and 73 ppb at the Denton County and Tarrant County monitors/receptors respectively. Preliminary 2019-
2021 DVs are 74 ppb and 72 ppb at the Denton County and Tarrant County monitors/receptors respectively.
*** Kenosha, WI Monitor ID. 550590025 was installed and began operating May 13, 2013, so the first three year DV available is 2013-2015. Racine, WI
Monitor ID. 551010020 was installed in April 14, 2014 so the first three year DV available is 2015-2017. TCEQ's modeling used monitored DV data for
2010-2012, 2011-2013, and 2012-2014 to project to the future year. Since these monitors do not have valid DVs for these periods, TCEQ's modeling can't
be used to project 2023 values and identify if they would be nonattainment or maintenance receptors.
The EPA investigated TCEQs modeling and the underestimation for the
future year. See the EPA Region 6 TSD for further information on our
review. Our review indicated some underestimation bias in the base case
and general model performance concerns but nothing that was a clear
cause of the much lower 2023 DVs that TCEQ's modeling is projecting.
For the EPA's 2016 base year modeling, the EPA undertook a large
collaborative multi-year effort with states (including Texas) and other
stakeholder input in developing the 2016 emission inventories including
2016v2, so that the EPA's modeling would be based on the best data
available. Using a 2016 base year also provides a more recent platform
that shortens the number of years to project emission changes, reducing
uncertainties in the 2023 projection compared to TCEQ's projection from
a 2012 base to 2023 or the EPA's earlier 2011 base year modeling. Use
of a more recent 2016 base year also allows for the use of monitored
DVs from a more recent period. The combination of these and other
issues discussed in the EPA Region 6 TSD result in less model
uncertainty compared to TCEQ's 2012 base year modeling and has provided
a better estimate of 2023 ozone levels and therefore, we believe a more
reliable tool for predicting which areas of the country will be
nonattainment or have difficulty maintaining the standard as well as
assessing contributions from upwind states.
The EPA's modeling using both 2011 and 2016 base year periods
identified that Texas was linked to nonattainment and/or maintenance
receptors in 2023 in the Midwest Region (Illinois, Wisconsin, and
Michigan), while TCEQ's modeling using a 2012 base year indicated only
linkages to western receptors. As discussed above and in the EPA Region
6 TSD, the TCEQ's modeling is underestimating projected ozone levels in
the Midwest Region for 2023. If TCEQ's 2023 modeled DVs were closer to
recent observed monitoring data and anticipated 2023 monitored DVs,
TCEQ would likely have also identified nonattainment and/or maintenance
receptors in the Midwest Region.
To summarize, TCEQ did its own modeling at Step 1. Our analysis
shows that TCEQ's modeling likely underestimates ozone levels at
potential receptors and that TCEQ's methodology for identifying
maintenance receptors used to identify maintenance receptors fails to
reasonably identify areas that will have difficulty maintaining the
NAAQS.
2. Evaluation of Information Provided by TCEQ Regarding Step 2
TCEQ, like the EPA, used a 1 percent of the ozone NAAQS (or 0.7
ppb) as the ``linkage'' threshold to identify states as ``linked'' for
contributions it made to areas with projected air quality problems.
Although TCEQ asserted that the EPA treats the 1 percent threshold as
the threshold by which the EPA determines ``significant contribution''
this is in fact incorrect. The EPA, like TCEQ, uses the 1 percent
contribution threshold to identify those linkages between a
contributing upwind state and a receptor projected to have air quality
problems that warrant further review and additional analysis. We
therefore endorse TCEQ' use of the 1 percent contribution threshold to
identify linkages requiring further analysis. However, because we
propose to disapprove TCEQ's identification of nonattainment and/or
maintenance receptors (at Step 1) due to underestimations in TCEQ's
modeling and their unsupported methodology of identifying maintenance
receptors, their submission as to Step 2 is also flawed. We note,
however, that even in its own modeling, TCEQ has identified
nonattainment and/or maintenance receptors to which it contributed more
than 1 percent of the NAAQS (i.e., identified linkages warranting
additional analysis at Step 3).
3. Results of the EPA's Step 1 and Step 2 Modeling and Findings for
Texas
As described in Section I and elsewhere in this action, the EPA
performed air quality modeling using the 2016v2 emissions platform to
project design values and contributions for 2023. This data was
examined to determine if Texas contributes at or above the threshold of
1 percent of the 2015 ozone NAAQS (0.70 ppb) to any downwind
nonattainment or maintenance receptor. As shown in Table TX-4, the data
\106\ indicate that in 2023, emissions from Texas are projected to
contribute greater than 1 percent of the standard to both
[[Page 9831]]
nonattainment and maintenance-only receptors in the Chicago, IL-IN-WI
nonattainment area (4 Cook County, IL receptors and 2 Kenosha County,
WI receptors) and the Milwaukee, WI nonattainment area (one Racine
County receptor).\107\
---------------------------------------------------------------------------
\106\ Design values and contributions at individual monitoring
sites nationwide are provided in the file:
``2016v2_DVs_state_contributions.xlsx'', which is included in docket
ID No. EPA-HQ-OAR-2021-0663.
\107\ These modeling results are consistent with the results of
a prior round of 2023 modeling using the 2016v1 emissions platform
which became available to the public in the fall of 2020 in the
Revised CSAPR Update, as noted in Section I of this action. That
modeling showed that Texas had a maximum contribution greater than
0.70 ppb to at least one nonattainment or maintenance-only receptor
in 2023. These modeling results are included in the file ``Ozone
Design Values And Contributions Revised CSAPR Update.xlsx'' in
Docket No. EPA-HQ-OAR-2021-0663.
Table TX-4--Projected Nonattainment and Maintenance Receptors With Texas Linkages Based on EPA 2016v2
----------------------------------------------------------------------------------------------------------------
Texas
Receptor (site ID, county, state) Nonattainment/ 2023 average 2023 maximum contribution
maintenance DV (ppb) DV (ppb) (ppb)
----------------------------------------------------------------------------------------------------------------
170310001, Cook, IL................... Maintenance............. 69.6 73.4 0.86
170310032, Cook, IL................... Maintenance............. 69.8 72.4 1.46
170314201, Cook, IL................... Maintenance............. 69.9 73.4 1.15
170317002, Cook, IL................... Maintenance............. 70.1 73.0 1.58
550590019, Kenosha, WI................ Nonattainment........... 72.8 73.7 1.72
550590025, Kenosha, WI................ Maintenance............. 69.2 72.3 1.81
551010020, Racine, WI................. Nonattainment........... 71.3 73.2 1.34
----------------------------------------------------------------------------------------------------------------
We recognize that the results of the EPA (2011 and 2016 base year)
and TCEQ (2012 base year) modeling indicated different receptors and
linkages at Steps 1 and 2 of the 4-Step interstate transport framework.
These differing results regarding receptors and linkages can be
affected by the varying meteorology from year to year, but we do not
think the differing results mean that the modeling or the EPA or the
State's methodology for identifying receptors or linkages is inherently
unreliable. Rather, the three separate modeling runs all indicated: (1)
There were receptors that would struggle with nonattainment or
maintenance in the future; and (2) Texas was linked to some set of
these receptors, even if the receptors and linkages differed from one
another in their specifics (e.g., a different set of receptors were
identified to have nonattainment or maintenance problems, or Texas was
linked to different receptors in one modeling run versus another).
These results indicate that emissions from Texas were substantial
enough to generate linkages at Steps 1 and 2 to some downwind
receptors, under varying assumptions and meteorological conditions,
even if the precise set of linkages changed between modeling runs.
Under these circumstances, we think it is appropriate to proceed to a
Step 3 analysis to determine what portion of emissions from Texas
should be deemed ``significant.'' In doing so, we are not agreeing with
the methods and assumptions contained in TCEQ's modeling (see previous
discussion and the EPA Region 6 TSD included in the docket for this
proposal for further discussion on evaluation of that modeling), or
that we consider our own earlier modeling to be of equal reliability
relative to more recent modeling. However, where alternative or older
modeling generated linkages, even if those linkages differ from
linkages in the EPA's most recent set of modeling (EPA 2016v2), that
information provides further evidence, not less, in support of a
conclusion that the State is required to proceed to Step 3 to further
evaluate its emissions.
Therefore, based on the EPA's evaluation of the information
submitted by TCEQ and based on the EPA 2016v2 modeling results for
2023, the EPA proposes to find that Texas 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.
4. Evaluation of Information Provided by TCEQ Regarding Step 3
At Step 3 of the 4-Step interstate transport framework, a state's
emissions are further evaluated, considering 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 effectively evaluate 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 approach (i.e.,
Step 3 of the 4-Step interstate transport framework) when identifying
emissions contributions that the Agency has determined to be
``significant'' (contribution to nonattainment 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. TCEQ did not demonstrate such an analysis
in their SIP submission. We therefore propose that TCEQ 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 Texas
failed to do so.
Instead, as noted in Section V.A of this action, TCEQ interpreted
the Act's requirements as only requiring an
[[Page 9832]]
analysis of emission reductions where ``there is a persistent and
consistent pattern of contribution on several days with elevated
ozone.'' TCEQ asserted that it would make the determination of whether
such pattern existed based on a weight-of-evidence approach that takes
into consideration air quality factors such as: Current attainment
status of the monitors, design value trends, the meteorological
conditions that lead to high ozone formation at the monitor, the number
of days with elevated observed ozone, back trajectories, Texas'
relative contribution on modeled high ozone days, Texas' contribution
as part of the collective interstate contribution to future modeled
DVs, alternate contribution method analysis, and model sensitivity runs
to reductions of Texas' emissions on receptors. However, TCEQ stated
that it did not consider or analyze all factors for every monitor.
Thus, different factors were analyzed for the receptors in different
regions (Colorado, Arizona, and Southern California). The EPA has
reviewed the different factors that TCEQ provided for each of the
regions in the EPA Region 6 TSD, but we will provide a brief summary of
the evaluation below. TCEQ also asserted that use of the 1 percent
threshold as the ``sole'' definition of significant contribution for
the 2015 ozone NAAQS is inappropriate. Based on the application of
selected factors for each of the monitors to which TCEQ's modeling
found that it was linked, TCEQ concluded that none of its contributions
to any other states were significant.
As explained above, TCEQ has mischaracterized the EPA's
interpretation of the CAA in stating that the EPA defines significant
contribution ``solely'' using a 1 percent threshold. The EPA, like
TCEQ, uses the 1 percent threshold to identify areas for further
analysis. The difference is that the EPA in past analyses has examined
potential emission reductions in linked upwind states and the air
quality impacts at downwind receptors that would result from the
implementation of those reductions to assess which contributions are
``significant.'' This interpretation of significant contribution, as
discussed above, has been upheld by the Supreme Court and the D.C.
Circuit.
As an initial matter, the EPA believes source apportionment
modeling, as performed by the EPA and also by TCEQ, to determine which
states are linked is an appropriate tool to identify impacts that are
persistent enough to impact a downwind receptors ability to attain or
maintain the standard. This approach is described in more detail above
in Section II.B.4 of this action, but, in summary, averages the
contributions from an upwind state for up to 10 days, which is
preferred, (but a minimum 5 days) at a given receptor. Given the ozone
standard is an average of the fourth high value from each of three
years, the EPA technique, also used by Texas, is appropriate to
identify impacts of sufficient persistence to impact a downwind
receptor's ability to attain or maintain the standard.
The EPA reviewed TCEQ's evaluation of the current attainment status
of the monitors and design value trends, and concludes, as described in
more detail in the EPA Region 6 TSD, that the provided information does
not support the large decreases in ozone levels that TCEQ's modeling
projects will occur by 2023. The analysis for California and Colorado
receptors provides evidence that TCEQ's photochemical modeling is
overestimating the ozone reductions expected at these receptors between
2012 and 2023 and actually presents evidence that more nonattainment
and/or maintenance receptors should have been identified.
The EPA also reviewed the trends in the number of high ozone days
per year provided by TCEQ for Colorado and California. While this data
supports that the number of ozone exceedance days is improving, neither
the analysis of the number of high ozone days in Colorado or California
provide any evidence to refute the TCEQ's photochemical modeling
results that show these areas should be considered nonattainment and/or
maintenance receptors. TCEQs modeling overestimates ozone reductions
yet still shows Texas linked to receptors at both nonattainment and
maintenance levels in 2023.
The TCEQ cited a conceptual model of ozone formation for areas in
Southern California. TCEQ indicated that Southern California is
isolated and transport into the basin is unlikely on a frequent basis,
but this information does not refute the TCEQ's modeling. As discussed
in Section III.B.3 of this action, photochemical modeling is the most
sophisticated tool available to estimate future ozone levels and
contributions to those modeled future ozone levels. Consideration of
the different processes that affect primary and secondary pollutants at
the regional scale in different locations is fundamental to
understanding and assessing the effects of emissions on air quality
concentrations. TCEQ's modeling showed transport at 10 monitors having
contributions greater than 0.7 ppb on average for the 5-10 days used in
the modeling analyses. Considering the form of the standard, this is a
sufficient number of days to determine if an impact is persistent
enough to impact an area's ability to attain or maintain the standard.
TCEQ used the National Oceanic and Atmospheric Administration
(NOAA) HYSPLIT \108\ model to produce back trajectories for all the
monitored ozone exceedance days (2007-2016) for the five receptors in
Colorado and 10 receptors in Southern California to evaluate how many
of the back trajectories went through Texas. TCEQ also used data from
these back trajectories to do an endpoint count analysis. We note that
we have several concerns with how TCEQ performed the back trajectories
including start time and heights, length (number of hours) of the back
trajectory, inappropriate removal of some back trajectories based on
start height, center-line height touch down, and trajectory center-line
height when over Texas, and inappropriate counting of trajectories by
not considering that the center-line represents the centerline of a
much wider area of air parcels that could have reached the monitor/
receptor. Due to these concerns, as discussed in more detail in the EPA
Region 6 TSD, the EPA finds the results of TCEQ's back trajectory and
endpoint analysis flawed (underestimates back trajectories that reach
Texas) and do not provide evidence that refutes the TCEQ photochemical
modeling analysis results.
---------------------------------------------------------------------------
\108\ See FN 34.
---------------------------------------------------------------------------
We note that even valid back trajectories are of limited use as
HYSPLIT simply estimates the path a parcel of air backward in hourly
steps for a specified length of time. HYSPLIT estimates the central
path in both the vertical and horizontal planes. The HYSPLIT central
path represents the centerline with the understanding that there are
areas on each side horizontally and vertically that also contribute to
the concentrations at the end point. The horizontal and vertical areas
that potentially contribute to concentrations at the endpoint (monitor)
grow wider from the centerline the further back in time the trajectory
goes. Therefore, a HYSPLIT centerline does not have to pass directly
over emissions sources or emission source areas, but merely relatively
near emission source areas for those areas, to contribute to
concentrations at the trajectory endpoint. The EPA relies on back
trajectory analysis as a corollary analysis along with observation-
based meteorological wind fields at multiple heights to examine the
general plausibility of the photochemical model
[[Page 9833]]
``linkages.'' Since the back trajectory calculations do not account for
any air pollution formation, dispersion, transformation, or removal
processes as influenced by emissions, chemistry, deposition, etc., the
trajectories cannot be used to develop quantitative contributions.
Therefore, back trajectories cannot be used to quantitatively evaluate
the magnitude of the existing photochemical contributions from upwind
states to downwind receptors. It is interesting to note that TCEQ's
analysis of the back trajectories indicates that the 2012 meteorology
used by TCEQ seemed to yield more back trajectories that reach Texas
than most years for many of the Colorado monitors. This seems to be
consistent with TCEQ identifying linkages to Colorado when the EPA's
modeling of 2016 does not.
TCEQ performed an alternate contribution analysis for the ten
California receptors and the five Colorado receptors using all days
modeled in 2023 that had values over 70 ppb rather than focus on just
the 5-10 highest values under the EPA's technique. Particularly for
California, this meant many more days could be included in the average
which had the effect of showing a smaller estimated contribution. We
believe it is appropriate to focus on the highest values as these are
the ones that ultimately will have to be reduced for the standard to be
attained. As discussed in the EPA Region 6 TSD, the EPA's review of
TCEQ's alternate contribution method analysis for California and
Colorado receptors is that it does not provide substantial evidence
that refutes the TCEQ's photochemical modeling analysis results,
including the contribution analysis using the EPA's contribution
methodology.
TCEQ provided an analysis of collective interstate contribution to
the 2023 DV for the five Colorado and ten California receptors. The
collective interstate contribution at tagged Colorado receptors ranges
from 9.32% to 10.27%. The collective interstate contribution at tagged
California receptors ranges from 3.2% to 4.58%. TCEQ argues that these
are small percentages (Colorado and California) and not as high as the
collective interstate contribution percentages the EPA calculated for
monitors in Eastern States, which ranged from 17% to 67%. TCEQ also
notes that a significant portion of the tagged Colorado monitors' 2023
modeled DVs is due to background emissions (sum of contributions from
to biogenic, fires, and boundary conditions). For the California
receptors TCEQ argues that these percentages are small compared to
Intra-State contribution.
As an initial matter, the EPA is not solely relying on TCEQ's
findings of linkages to Colorado and California but is also relying on
its own findings of linkages to areas in the Midwest Region. As such,
TCEQ's analysis of relative contributions to Colorado and California
does not provide justification for not addressing downwind impacts.
Nonetheless, EPA has found in the past that certain California
receptors are so heavily impacted by local emissions, and total upwind
contribution is so low, that those receptors may not be considered to
be affected by interstate ozone transport. See 81 FR 15200 (Mar. 22,
2016). However, this is a narrow circumstance that does not apply in
the vast majority of cases and has never been applied outside of
California. EPA has previously found, for instance, that receptors in
Colorado are heavily impacted by upwind-state contribution. See 82 FR
9155 (Feb. 3, 2017); 81 FR 71991 (Oct. 19, 2016). EPA need not draw any
conclusions here regarding whether the California sites TCEQ identified
should or should not be considered receptors for ozone-transport
purposes. EPA affirms, contrary to TCEQ's suggestion, that the Colorado
receptors TCEQ analyzed are impacted by upwind state contributions.
However, the EPA's finding that Texas is linked to receptors in other
states is based on still other linkages found in EPA's modeling to
receptors in other states, which are clearly impacted by the collective
contribution of multiple upwind states, including Texas. Under CAA
section 110(a)(2)(D)(i)(I) downwind states are not obligated to reduce
emissions on their own to resolve nonattainment or maintenance
problems. Rather, states are obligated to eliminate their own
significant contribution or interference with the ability of other
states to attain or maintain the NAAQS.
TCEQ also performed photochemical modeling analysis using the
Direct Decoupled Method (DDM) tool for receptors in Colorado. DDM
provides a first derivative of the changes in ozone (linear
relationship where the DDM value is the slope of the line for changes
in ozone) resulting from changes in NOX emissions from all
Texas' NOX emissions. The DDM modeling does show some
response to Texas NOX emissions but from the scale it is
hard to discern the level of response but it appears to be in the 0-2
ppb range in general with some values in the 0.2 -2 ppb range for
modeled values over 60 ppb. Since the modeling has underprediction and
underestimation issues, these values could be higher. Not surprisingly,
the DDM tool shows that monitors in Colorado are much more responsive
to intra-state reductions than reductions in Texas. That said, the
results of the DDM tool showing only a relatively small response to
reductions is not inconsistent with the finding that Texas emissions
contribute significantly to elevated readings in Colorado. As has been
discussed elsewhere, the EPA believes a contribution of 1 percent of
the standard is an appropriate threshold such that further analysis is
warranted.
Overall, these additional analyses performed by TCEQ do not provide
sufficient evidence to refute the modeling results that TCEQ's modeling
indicates downwind nonattainment and/or maintenance receptors in
Colorado and Southern California are impacted by Texas emissions and
Texas' contribution is 0.7 ppb or greater.\109\ In fact, the monitored
ozone design value trends provide evidence that future year modeled
ozone levels are underestimated by TCEQ's modeling and there are likely
more receptors that should have been identified with additional
potential linkages. Although Texas asserted that its additional air
quality factor analysis is a permissible way to interpret which
contributions are ``significant'' because that analysis examines
whether there was a ``persistent and consistent pattern of contribution
on several days with elevated ozone'' we find that such pattern is
already established by a modeled linkage at Step 2.
---------------------------------------------------------------------------
\109\ TCEQ also identified a monitor in Cochise County, Arizona
(ID 40038001), but the monitor's recent DVs are below the NAAQS.
From AQS, the 2014-2016 and 2015-2017 DVs are each 65 ppb; 2016-
2018, 2017-2019, and 2018-2020 DVs are 66 ppb; and preliminary 2019-
2021 DV is 66 ppb.
---------------------------------------------------------------------------
In addition, EPA 2016v2 modeling using 2016 base year meteorology
indicates linkages from Texas to receptors in the Midwest Region but
does not indicate impacts from Texas emissions on the Colorado and
other western receptors identified by TCEQ. With a different base
period such as TCEQ's 2012 base period meteorology and the EPA's 2016
base period meteorology, it is not uncommon that the potential downwind
nonattainment or maintenance receptors could change. These differing
results about receptors and linkages can be affected by the varying
meteorology from year to year and the selection of different base
years, but we do not think the differing results mean that the modeling
or the EPA methodology for identifying receptors or linkages is
inherently unreliable. Rather, these separate modeling runs indicated
(1) that there were receptors that would
[[Page 9834]]
struggle with nonattainment or maintenance in the future, and (2) that
Texas was linked to some set of these receptors, even if the receptors
and linkages differed from one another in their specifics (e.g., a
different set of receptors were identified to have nonattainment or
maintenance problems, or Texas was linked to different receptors in one
modeling run versus another). We think this common result indicates
that Texas's emissions were substantial enough to generate linkages at
Steps 1 and 2 to some set of downwind receptors, under varying
assumptions and meteorological conditions, even if the precise set of
linkages changed between modeling runs.
In sum, the EPA's more recent and robust 2016 base year modeling
platform indicates that Texas is linked to several receptors in the
Midwest Region as does the EPA's earlier 2011 base year modeling.
TCEQ's 2012 base case modeling showed linkages to states in the west.
As discussed, the EPA does not find the additional weight of evidence
evaluations conducted by TCEQ provide compelling reasons to discount
the impacts indicated in Colorado and California by the TCEQ modeling.
In fact, we think TCEQ's modeling likely underestimates these issues.
We therefore propose that Texas 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 Texas failed to do so.
5. Evaluation of Information Provided by TCEQ 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. Texas indicated that
because a number of counties in its state had been designated
nonattainment for the 2015 ozone NAAQS, there could be attainment
demonstration and potential controls contemplated in association with
those nonattainment designations.\110\ However, the State's interstate
transport submission did not revise its SIP to identify any specific
emission reductions, nor did it include a revision to its SIP to ensure
any such reductions were permanent and enforceable. The other control
measures identified in TCEQ's submission are, as noted by TCEQ, already
adopted and implemented measures and do not contain an evaluation of
additional emission control opportunities (or establish that no
additional controls are required). As a result, the EPA proposes to
disapprove TCEQ's submittal on the separate, additional basis that the
Texas has not included permanent and enforceable emissions reductions
in its SIP as necessary to meet the obligations of CAA section
110(a)(2)(d)(i)(I).
---------------------------------------------------------------------------
\110\ Pointing to anticipated upcoming emission reductions, even
if they were not included in the analysis at Steps 1 and 2, is not
sufficient as a Step 3 analysis, for the reasons discussed in
Section V.B.4 of this action. In this section, we explain that to
the extent such anticipated reductions are not included in the SIP
and rendered permanent and enforceable, reliance on such anticipated
reductions is also insufficient at Step 4.
---------------------------------------------------------------------------
6. Conclusion
Based on the EPA's evaluation of TCEQ's SIP submission, the EPA is
proposing to find that the Texas August 17, 2018, SIP submission
pertaining to interstate transport of air pollution 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 ozone NAAQS in any other state.
VI. Proposed Action
We are proposing to disapprove the SIP submissions from Arkansas,
Louisiana, Oklahoma, and Texas pertaining to interstate transport of
air pollution which will significantly contribute to nonattainment or
interfere with maintenance of the 2015 ozone NAAQS in other states.
Under CAA section 110(c)(1), the disapprovals would establish a 2-year
deadline for the EPA to promulgate FIPs for these states 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 ozone NAAQS in other states,
unless the EPA approves SIPs that meet these requirements. Disapproval
does not start a mandatory sanctions clock for Arkansas, Louisiana,
Oklahoma, or Texas.
VII. 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 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 proposed action disapproving the portion of Oklahoma's SIP
submission addressing the State's interstate transport obligations
under CAA section 110(a)(2)(D)(i)(I) for the 2015 ozone NAAQS will
apply to certain areas of Indian country as discussed in Section IV.C
of this action, and therefore, has tribal implications as specified in
E.O. 13175 (65 FR 67249, November 9, 2000). However, this proposed
action will neither impose substantial direct compliance costs on
federally recognized tribal governments, nor preempt tribal law. This
proposed action will not impose substantial direct compliance costs on
federally recognized tribal governments because no actions will be
required of tribal governments. This proposed action will
[[Page 9835]]
also not preempt tribal law as no Oklahoma tribe implements a
regulatory program under the CAA, and thus does not have applicable or
related tribal laws. Consistent with the EPA Policy on Consultation and
Coordination with Indian Tribes (May 4, 2011), the EPA will offer
consultation to tribal governments whose lands are located within the
exterior boundaries of the State of Oklahoma that may be affected by
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).\111\
---------------------------------------------------------------------------
\111\ 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.
---------------------------------------------------------------------------
The EPA anticipates that this proposed rulemaking, if finalized,
would be ``nationally applicable'' within the meaning of CAA section
307(b)(1) because it would take final action on SIP submittals for the
2015 ozone NAAQS for four states, which are located in three different
Federal judicial circuits. It would apply uniform, nationwide
analytical methods, policy judgments, and interpretation with respect
to the same CAA obligations, i.e., implementation of interstate
transport requirements under CAA section 110(a)(2)(D)(i)(I) for the
2015 ozone NAAQS for states across the country, and final action would
be based on this common core of determinations, described in further
detail below.
If the EPA takes final action on this proposed rulemaking[, in the
alternative,] 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 interstate transport 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 the 4-Step 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.\112\
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).\113\
---------------------------------------------------------------------------
\112\ 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.
\113\ 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 the EPA take a single final action on all such
disapprovals, this action would be nationally applicable, and the
EPA would also anticipate, in the alternative, making and publishing
a finding that such final action is based on a determination of
nationwide scope or effect.
---------------------------------------------------------------------------
List of Subjects in 40 CFR Part 52
Environmental protection, Air pollution control, Incorporation by
reference, Ozone.
Authority: 42 U.S.C. 7401 et seq.
Dated: February 1, 2022.
Earthea Nance,
Regional Administrator, Region 6.
[FR Doc. 2022-02961 Filed 2-18-22; 8:45 am]
BILLING CODE 6560-50-P
