Proposed Rule2026-06942
Air Plan Approvals; Indiana; Prong 4 (Visibility) for the 2015 Ozone National Ambient Air Quality Standard
Primary source
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Published
April 10, 2026
Issuing agencies
Environmental Protection Agency
Abstract
The Environmental Protection Agency (EPA) is proposing to approve a portion of Indiana's State Implementation Plan (SIP) submission regarding the infrastructure requirements of section 110 of the Clean Air Act (CAA) for the 2015 ozone National Ambient Air Quality Standards (NAAQS). The infrastructure requirements 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. The EPA is proposing that Indiana's infrastructure submission fulfills CAA requirements for a State's SIP to contain adequate provisions prohibiting emissions that will interfere with required visibility protection measures in any other State's SIP.
Full Text
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<title>Federal Register, Volume 91 Issue 69 (Friday, April 10, 2026)</title>
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[Federal Register Volume 91, Number 69 (Friday, April 10, 2026)]
[Proposed Rules]
[Pages 18347-18349]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2026-06942]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 52
[EPA-R05-OAR-2018--0788; FRL-13249-01-R5]
Air Plan Approvals; Indiana; Prong 4 (Visibility) for the 2015
Ozone National Ambient Air Quality Standard
AGENCY: Environmental Protection Agency (EPA).
ACTION: Proposed rule.
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SUMMARY: The Environmental Protection Agency (EPA) is proposing to
approve a portion of Indiana's State Implementation Plan (SIP)
submission regarding the infrastructure requirements of section 110 of
the Clean Air Act (CAA) for the 2015 ozone National Ambient Air Quality
Standards (NAAQS). The infrastructure requirements 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. The EPA is proposing that Indiana's infrastructure
submission fulfills CAA requirements for a State's SIP to contain
adequate provisions prohibiting emissions that will interfere with
required visibility protection measures in any other State's SIP.
DATES: Written comments must be received on or before May 11, 2026.
ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R05-
OAR-2018-0788 at <a href="https://www.regulations.gov">https://www.regulations.gov</a> or via email to
<a href="/cdn-cgi/l/email-protection#f29e939c959f939cdc9f9b919a93979eb2978293dc959d84"><span class="__cf_email__" data-cfemail="82eee3ece5efe3ecacefebe1eae3e7eec2e7f2e3ace5edf4">[email protected]</span></a>. For comments submitted at <a href="http://Regulations.gov">Regulations.gov</a>,
follow the online instructions for submitting comments. 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 <a href="https://www.regulations.gov">https://www.regulations.gov</a> any information you
consider to be confidential business information (CBI), Proprietary
Business Information (PBI), 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). For additional submission
methods, please contact the person identified in the FOR FURTHER
INFORMATION CONTACT section. For the full EPA public comment policy,
information about CBI or multimedia submissions, and general guidance
on making effective comments, please visit <a href="https://www.epa.gov/dockets/commenting-epa-dockets">https://www.epa.gov/dockets/commenting-epa-dockets</a>.
FOR FURTHER INFORMATION CONTACT: Michael Langman, Air and Radiation
Division (AR-18J), Environmental Protection Agency, Region 5, 77 West
Jackson Boulevard, Chicago, Illinois 60604, telephone number: (312)
886-
[[Page 18348]]
6867, email address: <a href="/cdn-cgi/l/email-protection#107c717e777d717e3e7d79737871757c507560713e777f66"><span class="__cf_email__" data-cfemail="2a464b444d474b4404474349424b4f466a4f5a4b044d455c">[email protected]</span></a>.
SUPPLEMENTARY INFORMATION: Throughout this document whenever ``we,''
``us,'' or ``our'' is used, we mean the EPA.
I. Background on Infrastructure SIPs
Whenever the EPA promulgates a new or revised NAAQS, CAA section
110(a)(1) requires States to make SIP submissions to provide for the
implementation, maintenance, and enforcement of the NAAQS. This SIP
submission is a particular type of SIP commonly referred to as an
``infrastructure SIP.'' These submissions must meet the various
requirements of CAA section 110(a)(2), as applicable. Due to ambiguity
in some of the language of CAA section 110(a)(2), the EPA believes that
it is appropriate to interpret these provisions in the specific context
of acting on infrastructure SIP submissions. EPA has previously
provided comprehensive guidance on the application of these provisions
through a guidance document for infrastructure SIP submissions (EPA's
2013 Guidance) and through regional actions on infrastructure
submissions.\1\ Unless otherwise noted below, we are following the same
approach in acting on this submission. In addition, in the context of
acting on such infrastructure submissions, the EPA evaluates the
submitting State's SIP for facial compliance with statutory and
regulatory requirements, not for the State's implementation of its
SIP.\2\ The EPA has other authority to address any issues concerning a
State's implementation of the rules, regulations, consent orders, etc.
that comprise its SIP.
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\1\ The EPA explains and elaborates on these ambiguities and its
approach to address them in its September 13, 2013, ``Guidance on
Infrastructure State Implementation Plan (SIP) Elements under Clean
Air Act sections 110(a)(1) and 110(a)(2)'' (available at <a href="https://www3.epa.gov/airquality/urbanair/sipstatus/docs/Guidance_on_Infrastructure_SIP_Elements_Multipollutant_FINAL_Sept_2013.pdf">https://www3.epa.gov/airquality/urbanair/sipstatus/docs/Guidance_on_Infrastructure_SIP_Elements_Multipollutant_FINAL_Sept_2013.pdf</a>), as well as in numerous agency actions, including the EPA's
prior action on Illinois', Michigan's, Minnesota's, and Wisconsin's
infrastructure SIPs to address the 2008 lead NAAQS (79 FR 27241 (May
13, 2014)).
\2\ See U.S. Court of Appeals for the Ninth Circuit decision in
Montana Environmental Information Center v. EPA, No. 16-71933
(August 30, 2018).
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II. What action is the EPA proposing?
The EPA is proposing to approve Indiana's November 2, 2018
infrastructure SIP submission for the 2015 ozone NAAQS addressing the
fourth component of CAA section 110(a)(2)(D)(i)(II), also known as
``Prong 4'', requirement that a State's SIP contain adequate provisions
prohibiting any source or other type of emissions activity within the
State from emitting any air pollutant in amounts which will interfere
with measures required to be included in the applicable SIP for any
other State to protect visibility.
Under the applicable requirements for visibility protection of CAA
section 110(a)(2)(D)(i)(II), States are subject to visibility and
regional haze program requirements under part C of the CAA, which
includes sections 169A and 169B. The EPA's 2013 Guidance states that
the Prong 4 requirements can be satisfied by approved SIP provisions
that the EPA has found to adequately address any contribution of that
State's sources that impact the visibility program requirements in
other States.\3\ According to the EPA's 2013 Guidance, a State's
infrastructure SIP may satisfy Prong 4 \4\ for any relevant NAAQS
through an air agency's confirmation that the State has a fully
approved regional haze SIP \5\ meeting the requirements of 40 CFR
51.308.
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\3\ The EPA's 2013 Guidance at 32-33.
\4\ In the EPA's 2013 Guidance, we indicated that it may be
appropriate to supplement the guidance regarding the relationship
between regional haze SIPs and Prong 4 after second implementation
period SIPs become due, which occurred on July 31, 2021. After a
review of the EPA's 2013 Guidance and the second implementation
period regional haze requirements, the EPA maintains the
interpretation that a fully approved regional haze SIP satisfies
Prong 4 requirements in the second implementation period.
\5\ Since second implementation period SIPs became due, a
``fully approved regional haze SIP'' would necessarily include fully
approved first and second implementation period regional haze SIPs.
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For the second implementation period, the EPA's Regional Haze
regulations under 40 CFR 51.308(f) require that a State consider the
emission reduction measures identified by other States as being
necessary to make reasonable progress towards meeting the national
visibility goal in Class I Federal areas. Specifically, the regulations
also require a State to include in its Regional Haze SIP all measures
agreed to during that process or measures that will provide equivalent
visibility improvement. 40 CFR 51.308(f)(2)(ii). Thus, in meeting the
requirements of 40 CFR 51.308(f), an approved regional haze SIP meeting
the statutory and regulatory requirements, including 40 CFR
51.308(f)(2)(ii), will ensure that emissions from sources under an air
agency's jurisdiction are not interfering with measures required to be
included in other air agencies' plans to protect visibility and will,
therefore, satisfy Prong 4.
III. The EPA's Evaluation of Indiana's Infrastructure SIP
To address the requirements of CAA section 110(a)(2)(D)(i)(II),
Indiana's infrastructure SIP submission for the 2015 ozone NAAQS
discusses the State's regional haze program. Indiana's regional haze
SIP submission for the second implementation period was fully approved
on January 26, 2026, 91 FR 3057.
For the reasons stated above, by meeting the statutory and
regulatory requirements of the regional haze program, including the
interstate consultation requirements in 40 CFR 51.308(f)(2)(ii),
Indiana's SIP adequately prohibits emissions from within the State that
would interfere with visibility protection measures in any other
State's SIP. Since Indiana has a fully approved regional haze SIP for
the second implementation period, which meets the requirements of 40
CFR 51.308, the EPA proposes that Indiana satisfies the requirements of
CAA section 110(a)(2)(D)(i)(II) relating to visibility protection for
the 2015 ozone NAAQS.
IV. Proposed Action
The EPA proposes to approve Indiana's November 2, 2018, interstate
transport infrastructure SIP submission as satisfying the requirements
related to visibility protection contained in CAA section
110(a)(2)(D)(i)(II), also known as Prong 4, for the 2015 ozone NAAQS.
V. Statutory and Executive Order Reviews
Under the CAA, the Administrator is required to approve SIP
submission that complies with the provisions of the CAA and applicable
Federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a). Thus, in
reviewing SIP submissions, the EPA's role is to approve State choices,
provided that they meet the criteria of the CAA. Accordingly, this
action merely approves State law as meeting Federal requirements and
does not impose additional requirements beyond those imposed by State
law. For that reason, this action:
<bullet> Is not a significant regulatory action subject to review
by the Office of Management and Budget under Executive Order 12866 (58
FR 51735, October 4, 1993);
<bullet> Is not subject to Executive Order 14192 (90 FR 9065,
February 6, 2025) because SIP actions are exempt from review under
Executive Order 12866;
<bullet> Does not impose an information collection burden under the
provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
<bullet> Is certified as not having a significant economic impact
on a
[[Page 18349]]
substantial number of small entities under the Regulatory Flexibility
Act (5 U.S.C. 601 et seq.);
<bullet> Does not contain any unfunded mandate or significantly or
uniquely affect small governments, as described in the Unfunded
Mandates Reform Act of 1995 (Pub. L. 104-4);
<bullet> Does not have federalism implications as specified in
Executive Order 13132 (64 FR 43255, August 10, 1999);
<bullet> Is not subject to Executive Order 13045 (62 FR 19885,
April 23, 1997) because it approves a State program;
<bullet> Is not a significant regulatory action subject to
Executive Order 13211 (66 FR 28355, May 22, 2001); and
<bullet> Is not subject to requirements of section 12(d) of the
National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272
note) because application of those requirements would be inconsistent
with the Clean Air Act.
In addition, the SIP is not approved to apply on any Indian
reservation land or in any other area where the EPA or an Indian Tribe
has demonstrated that a Tribe has jurisdiction. In those areas of
Indian country, the rule does not have Tribal implications and will not
impose substantial direct costs on Tribal governments or preempt Tribal
law as specified by Executive Order 13175 (65 FR 67249, November 9,
2000).
List of Subjects in 40 CFR Part 52
Environmental protection, Air pollution control, Incorporation by
reference, Nitrogen oxides, Ozone, Particulate matter, Sulfur oxides.
Dated: March 31, 2026.
Anne Vogel,
Regional Administrator, Region 5.
[FR Doc. 2026-06942 Filed 4-9-26; 8:45 am]
BILLING CODE 6560-50-P
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