Los Angeles County didn’t create the pollution problem, exactly, but now it must clean it up.

The runoff that flows from parking lots, industrial yards, driveways and just about everywhere else carries chemicals and contaminants that sicken swimmers in coastal waters.

Problem is, finding the source of those pollutants once they reach county drainage systems that carry it to the ocean is near impossible. But there is a way for the county to build drain systems that filter out pollution and prevents it from dirtying the water.

And now, with the Supreme Court upholding a circuit decision holding L.A. County liable for the pollution, the county will have to figure out some new designs.

That’s what environmentalists are counting on.