Proposed rule · 2025-07259

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

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<INF>X</INF>). 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).