04/27/2012 01:33 pm ET

Magic Mountain's Polluting One Of The Area's Largest Rivers, Environmentalists Say (VIDEO)

Next time you're at the top of a roller coaster at Six Flags Magic Mountain in Valencia, Calif., look down and notice the river that flows alongside the theme park. That river, the Santa Clara River, is the largest free-flowing river left in the Los Angeles area, according to environmentalists threatening to sue the theme park for allegedly polluting the river.

"What we see is really high levels of toxic metals, things like cadmium and copper and zinc," Liz Crosson, director of the Santa Monica-based nonprofit Bay Keeper, told ABC News. Crosson and other environmentalists say the pollutants flow to the Pacific Ocean and endanger human swimmers and wildlife.

In response, Magic Mountain issued a written statement saying it has done nothing wrong and is in full compliance with state guidelines. It also said that it is possible that some of the pollutants are coming from upstream rather than from the park.

If the theme park doesn't shape up within 60 days, it could be facing a lawsuit from Bay Keeper and several other environmentalist groups.