Air Plan Approval; Missouri; Removal of Obsolete Rules on Control of NOX Emissions

ENVIRONMENTAL PROTECTION AGENCY <CFR>40 CFR Part 52</CFR> <DEPDOC>[EPA-R07-OAR-2025-0138; FRL-12693-01-R7]</DEPDOC> <SUBJECT> Air Plan Approval; Missouri; Removal of Obsolete Rules on Control of NO <E T="0735">X</E> Emissions </SUBJECT> <HD SOURCE="HED">AGENCY:</HD> Environmental Protection Agency (EPA). <HD SOURCE="HED">ACTION:</HD> Proposed rule. <SUM> <HD SOURCE="HED">SUMMARY:</HD> The Environmental Protection Agency (EPA) is proposing approval of a State Implementation Plan (SIP) revision submitted by the Missouri Department of Natural Resources (MoDNR) on November 14, 2018. MoDNR requests that the EPA remove from its SIP two rules related to control of emissions of nitrogen oxides (NO <E T="52">X</E> ). One of the rules previously applied to electricity generating units (EGUs) and certain non-EGUs in a portion of the state and the other rule previously applied to EGUs throughout the entire state. The EPA has already approved a SIP revision that included provisions to sunset the two rules, and removal of the now-sunsetted rules from the SIP would not have an adverse effect on air quality. The EPA's proposed approval of this rule revision is being done in accordance with the requirements of the Clean Air Act (CAA). </SUM> <DATES> <HD SOURCE="HED">DATES:</HD> Comments must be received on or before May 29, 2025. </DATES> <HD SOURCE="HED">ADDRESSES:</HD> You may send comments, identified by Docket ID No. EPA-R07-OAR-2025-0138 to https:/ <E T="03">www.regulations.gov.</E> Follow the online instructions for submitting comments. <E T="03">Instructions:</E> All submissions received must include the Docket ID No. for this rulemaking. Comments received will be posted without change to <E T="03">https://www.regulations.gov,</E> including any personal information provided. For detailed instructions on sending comments and additional information on the rulemaking process, see the “Written Comments” heading of the <E T="02">SUPPLEMENTARY INFORMATION</E> section of this document. <FURINF> <HD SOURCE="HED">FOR FURTHER INFORMATION CONTACT:</HD> William Stone, Environmental Protection Agency, Region 7 Office, Air Permitting and Planning Branch, 11201 Renner Boulevard, Lenexa, Kansas 66219; telephone number: (913) 551-7714; email address: <E T="03">stone.william@epa.gov.</E> </FURINF> <SUPLINF> <HD SOURCE="HED">SUPPLEMENTARY INFORMATION:</HD> Throughout this document “we,” “us,” and “our” refer to the EPA. <HD SOURCE="HD1">Table of Contents</HD> <EXTRACT> <FP SOURCE="FP-2">I. Written Comments.</FP> <FP SOURCE="FP-2">II. What is being addressed in this document?</FP> <FP SOURCE="FP-2">III. Have the requirements for approval of a SIP revision been met?</FP> <FP SOURCE="FP-2">IV. What action is the EPA taking?</FP> <FP SOURCE="FP-2">V. Incorporation by reference.</FP> <FP SOURCE="FP-2">VI. Statutory and Executive Order Reviews.</FP> </EXTRACT> <HD SOURCE="HD1">I. Written Comments</HD> Submit your comments, identified by Docket ID No. EPA-R07-OAR-2025-0138, at <E T="03">https://www.regulations.gov.</E> Once submitted, comments cannot be edited or removed from egulations.gov. The EPA may publish any comment received to its public docket. Do not submit electronically 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 ( <E T="03">i.e.</E> on the web, cloud, or other file sharing system). For additional submission methods, the full EPA public comment policy, information about CBI or multimedia submissions, and general guidance on making effective comments, please visit <E T="03">https://www.epa.gov/dockets/commenting-epa-dockets.</E> <HD SOURCE="HD1">II. What is being addressed in this document?</HD> The EPA is proposing to approve the removal of 10 Code of State Regulations (CSR) 10-6.360, <E T="03">Control of NO</E> <E T="8145">x</E> Emissions From Electric Generating Units and Non-Electric Generating Boilers (referred to here as the Missouri NBTP Rule), and 10 CSR 10-6.350, <E T="03">Emission Limitations and Emissions Trading of Oxides of Nitrogen</E> (referred to here as the Missouri EGU Emission Rate Rule), from the Missouri SIP. <HD SOURCE="HD2">A. Background on the Missouri NBTP Rule</HD> In 1998, the EPA issued the NO <E T="52">X</E> SIP Call to address interstate ozone pollution for the 1979 and 1997 ozone national ambient air quality standards (NAAQS). 63 FR 57356 (October 27, 1998). As applied to Missouri after amendments, the NO <E T="52">X</E> SIP Call required the state to address interstate ozone pollution for the 1979 ozone NAAQS by revising its SIP to reduce NO <E T="52">X</E> emissions in the eastern one-third of the state during the May-September “ozone season” starting in 2007. 69 FR 21604 (April 21, 2004). The NO <E T="52">X</E> SIP Call included a model state rule for the NO <E T="52">X</E> Budget Trading Program (NBTP), an interstate cap-and-trade program for seasonal NO <E T="52">X</E> emissions. The NBTP was designed to cover existing and new EGUs over 25 MW (large EGUs) and existing and new non-EGU boilers and combustion turbines with maximum design heat input over 250 mmBtu/hr (large non-EGUs). States could meet most of their NO <E T="52">X</E> SIP Call obligations by revising their SIPs to include state rules that required these sources to participate in the NBTP. Missouri adopted the Missouri NBTP Rule in 2005 as part of the state's plan to address its NO <E T="52">X</E> SIP Call obligations. The rule applied only in the eastern one-third of the state, where existing and new large EGUs and existing large non-EGUs were required to participate in the NBTP starting in 2007. Contrary to NBTP requirements, the rule's applicability provisions did not cover new large non-EGUs, but the EPA nevertheless approved the rule into the state's SIP in 2006. 71 FR 46860 (August 15, 2006); <E T="03">see also</E> 71 FR 32291, 32296-97 (June 5, 2006) (discussing the EPA's reasons for proposing approval despite the rule's omission of new large non-EGUs). In 2005, the EPA issued the Clean Air Interstate Rule (CAIR) addressing interstate ozone pollution for the 1997 ozone NAAQS and interstate fine particulate matter (PM <E T="52">2.5</E> ) pollution for the 1997 PM <E T="52">2.5</E> NAAQS. 70 FR 25162, May 12, 2005; <E T="03">see also</E> 71 FR 25328 (April 28, 2006) (CAIR backstop Federal Implementation Plans (FIPs)). As applied to Missouri, CAIR's ozone-related provisions required the state to revise its SIP to reduce seasonal NO <E T="52">X</E> emissions statewide starting in 2009. CAIR included a model state rule for the CAIR NO <E T="52">X</E> Ozone Season Trading Program (the CAIR OS trading program), a new interstate cap-and-trade program that was designed to replace the NBTP starting with the 2009 ozone season. While CAIR called for the EPA to stop carrying out its functions administering the NBTP after the 2008 ozone season, the states' NO <E T="52">X</E> SIP Call obligations remained in effect and had to be met through other compliance mechanisms. <E T="03">See</E> 40 CFR 51.121(r). By default, the CAIR OS trading program applied only to existing and new large EGUs, but states covered by the NOx SIP Call could elect to also include their existing and new large non-EGUs, making it possible for the states to use the CAIR OS trading program as the compliance mechanism for meeting their ongoing NO <E T="52">X</E> SIP Call obligations as to both large EGUs and large non-EGUs. Missouri adopted 10 CSR 10-6.364, <E T="03">Clean Air Interstate Rule Seasonal</E> NO <E T="52">X</E> <E T="03">Trading Program</E> (referred to here as the Missouri CAIR OS Rule), in 2007. The rule required existing and new large EGUs throughout the state and existing and new large non-EGUs in the eastern one-third of the state to participate in the CAIR OS trading program, thereby addressing both the state's ozone-related CAIR obligations and the state's ongoing NO <E T="52">X</E> SIP Call obligations as to both large EGUs and large non-EGUs. The Missouri CAIR OS Rule applied to all the sources covered by the Missouri NBTP Rule (and to additional sources) and established similarly structured but generally more stringent requirements. Accordingly, to avoid duplicative requirements, when adopting the Missouri CAIR OS Rule the state also amended the Missouri NBTP Rule to sunset its implementation when implementation of the Missouri CAIR OS Rule began. The EPA approved the Missouri CAIR OS Rule and the amendments sunsetting the Missouri NBTP Rule into the state's SIP in 2007 and 2008, respectively. 72 FR 71073 (December 14, 2007); 73 FR 17890 (April 2, 2008). CAIR was remanded to the EPA for replacement in 2008. <E T="03">North Carolina</E> v. <E T="03">EPA,</E> 531 F.3d 896 (D.C. Cir. 2008), <E T="03">modified on rehearing,</E> 550 F.3d 1176 (D.C. Cir. 2008). In response to the remand, in 2011 the EPA issued the Cross-State Air Pollution Rule (CSAPR) addressing interstate ozone pollution for the 1997 ozone NAAQS and interstate PM <E T="52">2.5</E> pollution for the 1997 and 2006 PM <E T="52">2.5</E> NAAQS. 76 FR 48208 (August 8, 2011). As applied to Missouri after amendments, CSAPR's ozone-related provisions required the state's large EGUs to reduce seasonal NO <E T="52">X</E> emissions statewide starting in 2015 by participating in the CSAPR NO <E T="52">X</E> Ozone Season Trading Program (the CSAPR OS trading program), a new interstate cap-and-trade progra ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Preview showing 10k of 27k characters. 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