Which act regulates the discharge of pollutants into the waters of the United States?

The Clean Water Act (CWA) is the primary federal law in the United States that governs water pollution and regulates the discharge of pollutants into the waters. Enacted in 1972, the CWA aims to maintain and restore the integrity of the nation's waters by preventing point source pollution, which includes discharges from specific locations such as pipes or ditches.

The CWA establishes the National Pollutant Discharge Elimination System (NPDES), which requires permits for any entity that wishes to discharge pollutants into navigable waters. This regulatory framework is crucial for protecting water quality, safeguarding aquatic ecosystems, and ensuring that water bodies are safe for recreation and wildlife.

In the context of the other options: the Clean Air Act focuses on air quality and emissions, the Water Quality Act is more about aspects related to water quality but does not specifically regulate discharges like the CWA, and the Pollution Prevention Act emphasizes reducing waste at the source rather than regulating discharges directly. Therefore, the Clean Water Act is the most directly relevant to the regulation of pollutant discharges into U.S. waters.