Public Service Company of Colorado, Fort St. Vrain Station v. United States Environmental Protection Agency, and William K. Reilly, Administrator

We have only one issue before us: whether the Federal Water Pollution Control Act of 1972 (Clean Water Act), codified at 33 U.S.C. §§ 1251-1387, authorizes the Environmental Protection Agency (EPA) to impose effluent limitations on the internal waste streams of a National Pollutant Discharge Elimination System (NPDES) per-mittee. Every entity that wishes to discharge pollutants into the waters of the United States must obtain a NPDES permit from EPA or an authorized state agency. See 33 U.S.C. §§ 1311(a) & 1342; 40 C.F.R. §§ 122-136, 400-501. NPDES permits impose a variety of restrictions on…