Proposed rule · 2025-11825

Air Plan Approval; Missouri; Control of Sulfur Dioxide Emissions and Approval and Promulgation of State Plan (Negative Declaration) for Designated Facilities and Pollutants

The EPA is proposing to approve revisions to the Missouri State Implementation Plan (SIP) submitted by the State of Missouri. Missouri requests that EPA approve replacing the previous statewide sulfur dioxide (SO<INF>2</INF>) rule in the SIP with the latest version of a newer SO<INF>2</INF> rule (10 CSR 10-6.261). This action would result in a number of changes to the SIP, including removing outdated requirements as a result of facilities that have historically closed or switched from coal to lower sulfur fuels, as well as those that have become subject to more stringent SO<INF>2</INF> requirements elsewhere in the Missouri SIP. Other revisions include reinstating SO<INF>2</INF> emission limits for the Ameren-Labadie and Evergy-Hawthorn power plants that had been previously removed. The revisions do not impact the stringency of the SIP, nor do they impact the state's ability to attain or maintain the National Ambient Air Quality Standards (NAAQS). In conjunction with proposing approval of revisions to the Missouri SIP, the EPA is proposing to approve Missouri's negative declaration of sources subject to sulfuric acid production requirements submitted by the MoDNR to the EPA on May 4, 2022.