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

<RULE> ENVIRONMENTAL PROTECTION AGENCY <CFR>40 CFR Part 52</CFR> <DEPDOC>[EPA-R07-OAR-2025-0138; FRL-12693-02-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> Final rule. <SUM> <HD SOURCE="HED">SUMMARY:</HD> The Environmental Protection Agency (EPA) is taking final action to approve a revision to the State Implementation Plan (SIP) submitted by the Missouri Department of Natural Resources (MoDNR) on November 14, 2018. MoDNR requested 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 approval of this rule revision is being done in accordance with the requirements of the Clean Air Act (CAA). </SUM> <EFFDATE> <HD SOURCE="HED">DATES:</HD> This final rule is effective on September 15, 2025. </EFFDATE> <HD SOURCE="HED">ADDRESSES:</HD> The EPA has established a docket for this action under Docket ID No. EPA-R07-OAR-2025-0138. All documents in the docket are listed on the <E T="03">https://www.regulations.gov</E> website. Although listed in the index, some information is not publicly available, <E T="03">i.e.,</E> Confidential Business Information (CBI) or other information whose disclosure is restricted by statute. Certain other material, such as copyrighted material, is not placed on the internet and will be publicly available only in hard copy form. Publicly available docket materials are available through <E T="03">https://www.regulations.gov</E> or please contact the person identified in the <E T="02">FOR FURTHER INFORMATION CONTACT</E> section for additional information. <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 EPA. <HD SOURCE="HD1">Table of Contents</HD> <EXTRACT> <FP SOURCE="FP-2">I. What is being addressed in this document?</FP> <FP SOURCE="FP-2">II. Have the requirements for approval of a SIP revision been met?</FP> <FP SOURCE="FP-2">III. The EPA's Response to Comments</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. What is being addressed in this document?</HD> The EPA is approving the removal of 10 Code of State Regulations (CSR) 10-6.360, <E T="03">Control of NO</E> <E T="54">X</E> <E T="03"> Emissions From Electric Generating Units and Non-Electric Generating Boilers</E> (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="HD1">II. Have the requirements for approval of a SIP revision been met?</HD> The State submission has met the public notice requirements for SIP submissions in accordance with 40 CFR 51.102. The submission also satisfied the completeness criteria of 40 CFR part 51, appendix V. The State provided public notice on this SIP revision from February 28, 2018, to April 5, 2018 and received one comment from the EPA. Missouri's official submission addressed the EPA's comment. In addition, as explained above the revision meets the substantive SIP requirements of the CAA, including section 110 and implementing regulations. <HD SOURCE="HD1">III. The EPA's Response to Comments</HD> The public comment period on the EPA's proposed rule opened April 28, 2025, the date of its publication in the <E T="04">Federal Register</E> and closed on May 29, 2025. During this period, EPA received comments from four commenters. <E T="03">Comment 1:</E> One comment did not identify a specific issue that was relevant to the proposed rule and therefore does not require a response. The comment can be found in the docket for this action. <E T="03">Comment 2:</E> Two commenters were concerned that the removal of these rules could lead to an increase in “greenhouse gases (GHG) like Nox” emissions. <E T="03">Response:</E> As stated in the proposal, the rules were sunsetted in 2009 and have not been in effect since that time. This action has no effect on ozone-precursor emissions and thus, no direct or indirect effects with respect to GHGs or climate change. <E T="03">Comment 3:</E> The commenter stated that EPA should require an analysis of the air quality or public health impacts from removing these NO <E T="52">X</E> control rules, especially vulnerable and low-income groups. <E T="03">Response:</E> Please see response to Comment 2. Because the rules were sunsetted in 2009 and no substantive provisions of the Missouri NBTP Rule and the Missouri EGU Emission Rate Rule remain operative, this action has no effect on emissions or air quality. <E T="03">Comment 4:</E> The commenter stated that EPA should require Missouri to correct a compliance gap for large non-EGUs in eastern Missouri with a deadline. <E T="03">Response:</E> This action only removes obsolete provisions from the Missouri SIP. As noted in the NPRM, while the EPA has identified the existence of this compliance gap for NO <E T="52">X</E> SIP Call-affected large non-EGUs in eastern Missouri, the removal of the already-sunsetted rules from the state's SIP would not have any effect on the compliance gap. See 90 FR at 17754. As EPA further states in the NPRM, the EPA remains ready to assist Missouri in remedying the gap, but that remedy is beyond the scope of this action. <E T="03">Comment 5:</E> The commenter stated that EPA and Missouri should perform environmental justice reviews to prevent disproportionate impacts on marginalized, low-income, or Black communities for SIP revisions. <E T="03">Response:</E> Please see response to Comment 3. Because no substantive provisions of the Missouri NBTP Rule and the Missouri EGU Emission Rate Rule remain operative, the rules currently have no effect on emissions or air quality. <E T="03">Comment 6:</E> The commenter stated that NO <E T="52">X</E> emissions, seasonal trends and ozone readings should be publicly posted. <E T="03">Response:</E> The state of Missouri  <SU>1</SU> <FTREF/> and the EPA publicly post ozone levels from each monitor  <SU>2</SU> <FTREF/> and annual NO <E T="52">X</E> emissions are publicly available from the EPA's National Emissions Inventory (NEI). <SU>3</SU> <FTREF/> More detailed emissions data is available for sources regulated by the EPA's Clean Air Markets Program Data (CAMPD). <SU>4</SU> <FTREF/> <FTNT> <SU>1</SU>  Air Quality Analysis Ozone—Weekly Monitor Data | Missouri Department of Natural Resources. </FTNT> <FTNT> <SU>2</SU>  Air Quality Design Values | US EPA. </FTNT> <FTNT> <SU>3</SU>  Get Air Emissions Data | US EPA. </FTNT> <FTNT> <SU>4</SU>  Clean Air Markets Program Data (CAMPD) | US EPA. </FTNT> <E T="03">Comment 7:</E> The commenter stated that the rule should be reinstated if air quality deteriorates or the ozone non-attainment areas expand. <E T="03">Response:</E> As stated in the proposal, this rulemaking only removes obsolete provisions of the Missouri SIP. Further, these rules are no longer in effect and have not been since 2009. There are ongoing ozone season requirements for EGU sources. Missouri's large EGUs continue to participate in the interstate Cross-State Air Pollution Rule (CSAPR) Ozone Season Group 2 Trading Program (the CSAPR OS G2 trading program), as required by the Missouri CSAPR OS G2 Rule. See 90 FR at 17753. In addition, for the state's NO <E T="52">X</E> SIP Call-affected large non-EGUs, the Missouri Clean Air Interstate Rule (CAIR) OS Rule's requirements to monitor seasonal NO <E T="52">X</E> emissions in accordance with 40 CFR part 75 remain federally enforceable SIP requirements, notwithstanding the fact that the EPA has stopped carrying out its functions administering the trading program elements of that rule and the fact that the state has removed the rule from the state's regulations. Those monitoring requirements remain codified federal law. See id. 17753-54. <E T="03">Comment 8:</E> The commenter stated that EPA should track GHG emission co-benefits from EGU controls for NO <E T="52">X</E> . <E T="03">Response:</E> As stated in the proposal, this rulemaking only removes obsolete provisions of the Missouri SIP. GHG tracking is beyond the scope of the rulemaking. <E T="03">Comment 9:</E> The commenter stated that Missouri should do meaningful community engagement for SIP revisions and provide information in multiple languages. <E T="03">Response:</E> The State submission has met the public notice requirements for SIP submissions in accordance with 40 CFR 51.102. <E T="03">Comment 10:</E> The commenter stated that EPA should clarify how this action will be impacted by pending litigation on interstate transport. <E T="03">Response:</E> Since the rules being removed are no longer in effect and have not been since ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Preview showing 10k of 16k characters. 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