The Environmental Protection Agency (EPA) is proposing to approve a Clean Air Act (CAA) plan and two state rules submitted by the Missouri Department of Natural Resources (MoDNR) on July 25, 2022. This plan was submitted to fulfill the state's obligations under the CAA to implement and enforce the requirements of the Emissions Guidelines and Compliance Times for municipal solid waste (MSW) landfills. This plan includes an inventory of affected sources and explains how the state rules fulfill the regulatory requirements needed for EPA to approve the plan. In addition, the EPA is proposing to approve a revision to the State Implementation Plan (SIP) submitted by MoDNR for the purpose of revising the Missouri rule entitled ``Municipal Solid Waste Landfills'' to incorporate by reference Emission Guidelines (EG) for MSW landfills. EPA is proposing to approve this SIP revision based on EPA's finding that the rule is as stringent as the rule it replaces and fulfills the requirements of the CAA for the protection of the ozone National Ambient Air Quality Standards (NAAQS) in St. Louis.