Which statement describes the National Pollutant Discharge Elimination System (NPDES)?

• A. A permit system for regulating point sources of pollution.
• B. A permit system for regulating nonpoint sources.
• C. A program for air emissions.
• D. A program for groundwater recharge.

Answer: (A)

NPDES is a permit system under the Clean Water Act that controls discharges from point sources into U.S. waters. A point source is a definite, identifiable outlet such as a pipe, ditch, or smokestack from which pollutants are released. The program requires a permit that sets effluent limits, requires monitoring and reporting, and ensures discharges meet water-quality standards. This focus on controlled discharges from specific sources distinguishes it from regulation of nonpoint sources (like diffuse runoff), air emissions, or groundwater recharge, which are governed by different programs. So the statement describing NPDES as a permit system for regulating point sources of pollution is the best fit.