Air Plan Approvals; Indiana; Prong 4 (Visibility) for the 2015 Ozone National Ambient Air Quality Standard

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.

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.

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:

• 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);
• Is not subject to Executive Order 14192 (90 FR 9065, February 6, 2025) because SIP actions are exempt from review under Executive Order 12866;

• Does not impose an information collection burden under the provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq. );

• Is certified as not having a significant economic impact on a substantial number of small entities under the Regulatory Flexibility Act (5 U.S.C. 601 et seq. );

• Does not contain any unfunded mandate or significantly or uniquely affect small governments, as described in the Unfunded Mandates Reform Act of 1995 (Pub. L. 104-4);
• Does not have federalism implications as specified in Executive Order 13132 (64 FR 43255, August 10, 1999);
• Is not subject to Executive Order 13045 (62 FR 19885, April 23, 1997) because it approves a State program;
• Is not a significant regulatory action subject to Executive Order 13211 (66 FR 28355, May 22, 2001); and
• 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).

⁽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 https://www3.epa.gov/airquality/urbanair/sipstatus/docs/Guidance_on_Infrastructure_SIP_Elements_Multipollutant_FINAL_Sept_2013.pdf ), 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).

⁽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.