EPA Review Process under Section 309 of the Clean Air Act
EPA reviews all draft Environmental Impact Statements (EIS) prepared by other federal agencies, as well as other certain federal actions, as required by Section 309 of the Clean Air Act. Section 309 also requires that EPA make these reviews public, and EPA does this by posting EPA comment letters on EISs in the EIS database.
EPA's reviews on draft EISs are primarily concerned with identifying and recommending appropriate measures to avoid and mitigate significant environmental impacts associated with the proposal. EPA also evaluates the adequacy of the information presented in the EIS.
EPA also conducts reviews of final EISs to ensure that the lead agency has taken EPA's comments into account. If the project remains environmentally unsatisfactory, EPA may refer the matter to the Council on Environmental Quality (CEQ).
EPA has prepared an implementation memo that provides direction to EPA staff carrying out the agency's review responsibilities under the National Environmental Policy Act and Section 309 of the Clean Air Act. The documents listed below supersede the direction provided in the July 2025 “Policy and Procedures for the Review of Major Federal Actions with Environmental Impacts”.