Stormwater Permit Share Print The 1987 amendment to the Clean Water Act required that the Environmental Protection Agency (EPA) issue National Pollutant Discharge Elimination System (NPDES) Municipal Stormwater permits for discharges from large Municipal Separate Storm Sewer Systems (MS4s). An NPDES permit allows clean stormwater discharges into rivers, lakes, or the ocean. The California State Water Resources Control Board (Los Angeles Region) issues NPDES permits in the Los Angeles area with the permit requiring a decrease in pollutants in stormwater and urban runoff. The City of Carson complies with all requirements of the NPDES municipal permit. To see the City of Carson's NPDES MS4 permit, please click HERE.