Natural Resources Defense Council V.united States Environmental Protection Agency

BACKGROUND

A. Statutory Background

Congress enacted the CWA “to restore and maintain the chemical, physical, and biological integrity of the Nation’s 1 We cite to the original Act throughout this opinion, and provide a par- allel cite to the U.S. Code only the first time we cite each CWA provision. See Our Children’s Earth Found. v. EPA, 527 F.3d 842, 845 n.1 (9th Cir. 2008) [hereinafter OCEF]. 2 As used throughout this opinion, the term “Defendants” refers to the EPA and industry-intervenors. The term “Plaintiffs” refers to NRDC and state-intervenors. NRDC v. USEPA 13151 waters.” 33 U.S.C. § 1251(a). In furtherance of the CWA’s objective of eliminating the “discharge of pollutants into the navigable waters,” id., the Act prohibits the “discharge of any pollutant.” CWA § 301(a), 33 U.S.C. § 1311(a). The CWA defines the “discharge of a pollutant” as “any addition of any pollutant to navigable waters from any point source.” CWA § 502(12), 33 U.S.C. § 1362(12). A “point source” is “any discernable, confined and discrete conveyance, including but not limited to[,] any pipe, ditch, channel . . . from which pol- lutants are or may be discharged.” CWA §…