Rep. Oberstar, D-Minn., and Sen. Feingold, D-Wis., with the support of environmentalists, introduced legislation in the 111th Congress which would have expanded the scope of the Clean Water Act (CWA) by replacing the term ‘navigable waters’ with ‘waters of the U.S.’. The legislation died and EPA now is seeking to address the issue in guidance documents.

A draft version of the document was sent to the White House Office of Management and Budget (OMB) for review in December. The guidance will "significantly" expand regulators' ability to oversee wetlands and other marginal waters compared to earlier guidance prepared by the Bush Administration.

At issue are two Supreme Court rulings that environmentalists say have narrowed the law's jurisdiction over isolated wetlands, intermittent streams and other marginal waters. In Solid Waste Agency of Northern Cook County (SWANCC) v. Army Corps of Engineers, the court limited the basis for asserting jurisdiction over solely intrastate waters, while in Rapanos v. United States, the court provided two competing tests for determining jurisdiction. Justice Kennedy's test for determining jurisdiction states that water bodies must have a "significant nexus" to "navigable waters", while Justice Antonin Scalia offered a stricter test that required regulators to show a relatively permanent surface connection with a traditionally navigable water to assert jurisdiction.

An EPA spokesperson says that recent interpretations of the CWA "have removed long-standing pollution protections for many American waterbodies" and that the agency and Corps of Engineers are "clarifying the scope" of the CWA with the guidance.

Even before its public release, the guidance is prompting stiff opposition from industry groups. House Republicans included language in their spending plan for the remainder of FY11 that blocks EPA from issuing the guidance.