The federal statute that created national goals of reducing releases of toxic materials into US waters and achieving surface water standards (33 U.S.C. §§ 1251-1387). The CWA covers all waters that have a significant nexus to navigable waters. The existence of a nexus is a frequent topic of litigation. The scope of covered waters was often disputed until the Supreme Court clarified it in 2006.

Determinations of compliance with regulations involve measuring water quality and examining satisfaction of certain technology-based standards, such as sewage treatment plant requirements. Although some exceptions exist, pollution sources may not emit into surface waters without receiving a permit under the National Pollutant Discharge Elimination System (NPDES).

US citizens may bring suits against entities suspected of violating the CWA. An employee who faces adverse employment action related to CWA enforcement may file a complaint with the Occupational Safety and Health Administration (OSHA).