In a March 30 ruling, the U.S. District Court for the Central District of California found Los Angeles County and the Los Angeles Flood Control District liable for violating the terms of a 2001 National Pollutant Discharge Elimination System (NPDES) permit. While the court ruled that compliance with a newer 2012 NPDES permit should be sufficient to address stormwater pollution, the county and flood control district could face civil penalties for nearly 500 instances of water quality violations detected by in-stream monitors since 2003, in Malibu Creek as well as in the Los Angeles and San Gabriel rivers.

The Natural Resources Defense Council and Los Angeles Waterkeeper sued the defendants in 2008, and the case is now in its seventh year of litigation. In August 2013, the Ninth Circuit Court of Appeals ruled that the county and flood control district were liable for violating a municipal separate storm sewer system permit, but the court sent the case to the district court to determine the appropriate remedy.