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Compared with traffic, crime, and celebrity felonies, dirty stormwater isn't the first problem most people associate with Los Angeles County. Yet billions of gallons of polluted stormwater contaminate the county's beaches every year, afflicting swimmers with infections and gastrointestinal illnesses. In 2008 NRDC sued the county for allowing this pollution to enter rivers and flow into coastal waters, and last year a federal court agreed that the county was violating the Clean Water Act.

Now the case will head to the U.S. Supreme Court. According to county officials, who appealed the ruling, upstream factories, power plants, and other sources of pollution, not the county, should be responsible for preventing pollutants such as copper and lead from entering stormwater in the first place. NRDC lead attorney Aaron Colangelo disputes the county's claim. "The federal Clean Water Act doesn't care where the pollution originally comes from," he says. "What matters is where it's eventually discharged." The county is responsible for the pollution it fails to capture and treat, Colangelo explains, even if that pollution was created upstream.

Instead of litigating, says Colangelo, the county could clean the stormwater, and improve its residents' quality of life, through green infrastructure solutions, such as planting trees and rain gardens and constructing green roofs. Whether this vision becomes reality rests with the Supreme Court.