(Corrects name of council to Natural from National par 2)
By Mica Rosenberg
May 5 (Reuters) - The U.S. Supreme Court on Monday declined to review a ruling that found Los Angeles County liable for pollution runoff into Southern California rivers after big rain storms, in a decision hailed by environmentalists who brought the case.
The Natural Resources Defense Council, or NRDC, filed a lawsuit in 2008 arguing the county was responsible for contamination of billions of gallons of stormwater flowing into drains and then into the Los Angeles and San Gabriel rivers.
Rainwater mixes with a slurry of toxic chemicals and fecal bacteria from city streets. The suit alleged that pollution ending up in the rivers exceeded what was allowed by the county's permit, in violation of federal water quality laws.
Last August, the 9th U.S. Circuit Court of Appeals sided with the NRDC. By refusing to take up the case, the Supreme Court allowed that ruling to stand.
"This puts an end to questions of liability; the county has run out of appeals on whether it violated the Clean Water Act," said Steve Fleischli, a senior NRDC attorney. Now the case will return to the district court to determine how to remedy the violations, he said.
Los Angeles County has monitoring stations down river to test if levels of pollutants meet the standards of its National Pollutant Discharge Elimination System permit, which covers water runoff from more than 80 cities.
The flood control district manages a massive system of around 500 miles of open channel and 2,800 miles of storm drains.
The county has argued that it should not be held liable for violations of the permit because the data does not exactly show where the discharge is coming from and there are so many sources of water flowing into the system.
"This could force municipalities to redirect limited public funds from other critical services to spend on controlling pollution from private and other sources who are the responsible parties," Gail Farber, director of the Los Angeles County public works department, said in a statement.
The NRDC wants the county to build green infrastructure projects to help curb the runoff, like installing rain barrels or planting parks that collect or absorb the stormwater.
But it is not clear yet what remedy - if any - the district court will determine is needed in the case, said Howard Gest, who served as outside counsel for Los Angeles county.
He said the NRDC case is based on an outdated permit from 2001 that was updated in 2012. Under the new permit, the city is already building multi-use projects to deal with the stormwater, he said.
The county is likely to continue fighting the case which has made it to the Supreme Court before. In January 2013, the high court ruled in the county's favor on a very narrow question about what constitutes "discharge" of pollutants.
The case is Los Angeles County Flood Control District, et al. v. Natural Resources Defense Council, et al., Supreme Court of the United States, No. 13-901. (Editing by Ken Wills)