Solid Waste Agency of Northern Cook County (SWANCC) v. U.S. Army Corps of Engineers, 531 U.S. 159 (2001), was a decision by the US Supreme Court that interpreted a provision of the Clean Water Act. Section 404 of the Act requires permits for the discharge of dredged or fill materials into "navigable waters," which is defined by the Act as "waters of the United States." That provision was the basis for the federal wetlands-permitting program.