The Waters Advocacy Coalition (“WAC”) offers the following comments on the Environmental Protection Agency’s (“EPA”) and U.S. Army Corps of Engineers’ (“Corps”) (collectively, the “Agencies”) proposed revised definition of “waters of the United States” (“WOTUS”) under the Federal Water Pollution Control Act, as amended, also known as the Clean Water Act (“CWA” or “Act”),1 Updated Definition of “Waters of the United States,” 90 Fed. Reg. 52,498 (Nov. 20, 2025) (hereinafter, “Proposed Rule”). WAC appreciates the Agencies’ efforts to improve regulatory predictability and consistency by further clarifying the scope of WOTUS. When Congress enacted the CWA, it exercised its commerce power over navigation and specifically granted the Agencies the power to regulate “navigable waters,” which the CWA defines as “waters of the United States.” For decades, the Agencies’ regulations and guidance—coupled with the Agencies’ implementation and enforcement activity—steadily expanded the definition of WOTUS beyond constitutional and statutory boundaries. The Proposed Rule represents an important move toward realigning the regulatory definition of WOTUS with Congress’s intended scope of federal regulatory authority under the CWA. It gives meaning to Congress’s use of the term “navigable” throughout the statute and respects the CWA’s express policy to preserve the states’ traditional and primary authority over land and water use. Moreover, by codifying definitions of key terms that are central to determining the scope of the CWA’s reach, the Proposed Rule reduces the serious due process concerns associated with WOTUS regulations.