More than 40 years after Congress passed the landmark Clean Water Act, the jurisdictional reach of that statute remains a contentious legal and political issue. By prohibiting the discharge of pollutants to “navigable waters” without a permit, the Act expressly limits its protections to “navigable waters.” The statute defines “navigable waters” as “waters of the United States,” but fails to define that latter term. Congress’ omission led to more than three decades of federal rulemaking and Supreme Court litigation, which has yet to clarify this critical jurisdictional issue.

In their latest rulemaking effort, the United States Environmental Protection Agency (USEPA) and the U.S. Army Corps of Engineers (Corps) released the “Clean Water Rule” on May 27, 2015, offering their most recent interpretation of “waters of the United States.” The validity, scope and impact of the Clean Water Rule remain heavily disputed, and the rule is expected to trigger judicial challenges and possibly a legislative response from Congress (including S. 1140 and H.R. 1732). In the meantime, the regulated community must make sense of this complex rulemaking, estimated by some to affect as much as 60 percent of the land in the United States.