The Environmental Protection Agency (EPA) is proposing to approve a Clean Air Act (CAA or the ``Act'') section 111(d) state plan submitted by the South Dakota Department of Environment and Natural Resources (DENR or the ``Department'') on January 3, 2020. This plan was submitted to fulfill the requirements of the CAA and is responsive to the EPA's promulgation of Emission Guidelines and Compliance Times for existing municipal solid waste (MSW) landfills.