Who is responsible for regulating discharges of potentially contaminated wastewater and stormwater into waters of the US?

The National Pollutant Discharge Elimination System (NPDES) is the correct choice because it is a program under the Clean Water Act that is specifically designed to regulate discharges of pollutants into U.S. waters. The NPDES permits set the requirements for controlling the quantity and quality of wastewater and stormwater discharges, ensuring that they are managed in a way that protects water quality and public health.

While the Environmental Protection Agency (EPA) oversees the NPDES program, the NPDES itself represents the regulatory framework applied to entities that discharge pollutants, including those from industrial, municipal, and stormwater sources. Therefore, the NPDES provides the specific mechanism through which discharges are regulated.

State environmental agencies play a role in implementing the NPDES program and may administer the permits; however, their authority to do so stems from the framework established by the NPDES. The Federal Aviation Administration (FAA) does not regulate water discharges, as its focus is on aviation safety. Thus, the NPDES is the authoritative mechanism that directly relates to the regulation of wastewater and stormwater discharges into U.S. waters.