Construction industry officials say they are pleased with the U.S. Supreme Court’s Jan. 8 ruling in the first of two water-related cases argued before the court in December.

The court unanimously ruled in Los Angeles County Flood Control District v. Natural Resources Defense Council and L.A. Waterkeeper that the flood-control district did not violate its State Pollutant Discharge Elimination System (SPDES) permit when it simply transferred already polluted water from one portion of its river system to another.

The Natural Resources Defense Council (NRDC) and L.A. Waterkeeper filed a lawsuit in 2008 when water monitors within the Los Angeles County Flood Control District’s river system showed that stormwater runoff that flowed into the Los Angeles and San Gabriel rivers caused water-quality standards to be degraded hundreds of times. The environmental groups said they found evidence of mercury, arsenic, cyanide, lead and fecal bacteria that exceeded health limits.

The L.A. County Flood Control District had argued that there was no way to pinpoint who was responsible for the pollution because several sources discharged into the river system.

The 9th U.S. Circuit Court of Appeals held that the flood district had violated its permit. But the Supreme Court disagreed and reversed the appellate court ruling. “We hold … that the flow of water from an improved portion of the very same waterway does not qualify as a discharge of pollutants under the Clean Water Act,” wrote Justice Ruth Bader Ginsburg.

“We’re very happy with the decision that came out of the Supreme Court,” says Tom Ward, vice president of legal services and litigation at the National Association of Home Builders, which had filed a friend-of-the-court brief on behalf of the flood-control district.

But environmental groups say the narrow ruling does not excuse the county from mitigating ongoing water pollution in the Los Angeles and San Gabriel rivers.

“We’ll continue to hold the Los Angeles County Flood Control District responsible for cleaning up its water pollution,” says Steve Fleischli, senior attorney and director of NRDC’s national water program. “Unless something changes, stormwater pollution will continue to sicken up to one million people in Southern California every year, while local government turns a blind eye and avoids basic infrastructure solutions that will protect people, preserve water quality and increase water reserves.” To prevent the flow of pollutants into the rivers, green infrastructure systems could capture the stormwater at the source, Fleischli notes.

Shortly after the court issued its ruling, the flood-control district issued a statement from Gail Farber, its chief engineer and director of the County of Los Angeles Dept. of Public Works, that said, “Our work is not done. The fight for clean water is ongoing and remains a collective priority for the District and our many water-quality stakeholders within the region.”

Construction industry officials say they were interested in the case because of the possibility that the Supreme Court justices could have offered a broad ruling that would have expanded the SPDES requirements. “It’s one of those things we didn’t want to get bigger than it was,” Ward says.

Contractors typically put culverts in streams and rivers. Although they are not currently subject to a permit, a broad ruling in the case could have raised the argument that the water flowing out of pipes into streams and rivers should be subject to permits, Ward says.