Los Angeles County Flood Control Dist. v. NRDC

Justia Summary

Los Angeles County Flood Control District operates a “municipal separate storm sewer system” (MS4) drainage system that collects, transports, and discharges storm water. Because storm water is often heavily polluted, the Clean Water Act (CWA) and regulations require certain MS4 operators to obtain a National Pollutant Discharge Elimination System (NPDES) permit before discharging storm water into navigable waters. The District has such a permit for its MS4. Environmental groups filed a citizen suit under the CWA, 33 U. S. C.1365, alleging that water-quality measurements from monitoring stations within the Los Angeles and San Gabriel Rivers demonstrated that the District was violating its permit. The district court granted summary judgment, concluding that the record was insufficient to warrant a finding that the MS4 had discharged storm water containing the standards-exceeding pollutants detected at the downstream monitoring stations. The Ninth Circuit reversed in part, holding that the District was liable for discharge of pollutants that occurred when the polluted water detected at the monitoring stations flowed out of the concrete-lined portions of the rivers, where the monitoring stations are located, into lower, unlined portions of the same rivers. The Supreme Court reversed. The flow of water from an improved portion of a navigable waterway into an unimproved portion of the same waterway does not qualify as a “discharge of a pollutant” under the CWA.