On December 30, 2022, the U.S. Environmental Protection Agency (EPA) and the U.S. Army Corps of Engineers (collectively Agencies) announced the issuance of a final rule defining “waters of the United States” (WOTUS), a key term in the Clean Water Act (CWA). That phrase, which serves as the definition for “navigable waters” in the statute, effectively establishes the boundaries of the Agencies’ regulatory authority under the CWA. The rule was published in the Federal Register on January 18, 2023, and will take effect 60 days thereafter.