What must facilities obtain when discharging wastewater to surface waters?

The correct answer is that facilities must obtain a National Pollutant Discharge Elimination System (NPDES) permit when discharging wastewater to surface waters. This requirement stems from the Clean Water Act, which regulates the discharge of pollutants into U.S. waters. The NPDES permit system is crucial because it establishes a legal framework for controlling water pollution by providing guidelines on the types and amounts of waste that can be discharged. This ensures that the discharge does not negatively impact water quality and aquatic ecosystems.

The NPDES permit outlines specific conditions for discharges, including monitoring and reporting requirements, which help maintain compliance with environmental standards. Facilities that discharge treated wastewater must have this permit to legally manage their effluent and protect both public water supplies and biodiversity in nearby water bodies.

Other types of permits mentioned, such as a wastewater discharge permit or an industrial wastewater permit, may cover specific types of waste or industry requirements, but they do not encompass the broad regulatory framework provided by the NPDES, which is specifically aimed at the discharge of pollutants into surface waters. A stormwater management permit pertains to the control of stormwater runoff, which is a different aspect of water pollution management.