On the final day of the 2021-2022 term, the U.S. Supreme Court released its decision in West Virginia v. Environmental Protection Agency. The majority (6-3) opinion limited the U.S. Environmental Protection Agency’s (EPA’s) authority to regulate greenhouse gas emissions from power plants under Clean Air Act §111(d), in part by invoking the “major questions doctrine.” The decision has implications for EPA’s authority both to regulate emissions from stationary sources and to regulate greenhouse gases more broadly.

This Comment examines the legal framework for state protection of nonfederal waters and its implications for cooperative federalism. After a brief overview and legal background, it identifies some recent state actions that attempt to fill gaps in coverage created by changes in federal interpretations of the Clean Water Act. It then summarizes the current scope of state regulation of waters in every state, in order to discern the likely impact of changes at the federal level on the status of waters in the states.