The court of appeals affirmed a district court judgment in part, reversed in part, and remanded the action for further proceedings. The court held that mass-emission readings from measuring stations located inside portions of a municipal separate storm sewer system supported a finding that a county flood control district violated a National Pollutant Discharge Elimination System permit by discharging stormwater runoff pollutants into two rivers.
The Natural Resources Defense Council, Inc. and Santa Monica Baykeeper (NRDC) sued Los Angeles County, the Los Angeles County Flood Control District, and various public officials for violations of the Clean Water Act. According to NRDC, the County and the District unlawfully discharged polluted urban stormwater runoff collected by municipal separate storm sewer systems (MS4) into Southern California waters.
