Spill Closes Portion of Chino Hills Park

Several acres of the Chino Hills State Park remained closed this weekend as efforts continued to clean up a chemical spill that contaminated a creek bed and caused a chemical burn on one bicyclist, state officials said Sunday.

An estimated 466 gallons of water containing a high level of sodium hydroxide--a powdered chemical commonly added to drinking water--apparently leaked into the Telegraph Canyon creek south of Carbon Canyon Road for several days before it was discovered on Oct. 28, a Department of Fish and Game warden said.

A cyclist on a mountain bike crossed the creek and later felt an itching and burning sensation on his feet, warden Ralph Sugg said. The cyclist went to a local hospital, and physicians diagnosed his ailment as a “chemical burn,” Sugg said.

Hazardous material specialists with the Brea and Orange County fire departments traced the chemical leak to the Metropolitan Water District’s Diemer filtration plant on a ridge above Telegraph Canyon, less than a half mile from the creek.

“It appears that the water carrying the chemical was slowly trickling out of a pressure relief valve,” Sugg said. “MWD quickly sealed it off, but the cleanup is going to take some time.”

Sodium hydroxide is added to public drinking water supplies to prevent lead and acid buildup. When diluted in large water supplies, such as reservoirs, the chemical poses no health hazard. But when humans are exposed to the widely used industrial chemical in large concentrations, it can cause eye and skin irritation.

The 466 gallons of water that contaminated the creek had a “50% solution” of sodium hydroxide, Sugg said. He estimated that about a half mile of the creek was polluted, including three to four feet of soil on either side of the creek bed.

Telegraph Canyon is on the western edge of the 11,000-acre Chino Hills State Park, and the dirt road that runs through the canyon and along the creek is popular among hikers, cyclists and horse riders. But it remained closed Sunday as cleanup crews continued to remove tainted soil and vegetation from the creek bottom. A chain-link fence has been erected across the road, and the MWD has posted guards to keep outsiders away.

Mike Black, an Anaheim resident who often rides horses in the canyon, said he was angered Sunday when the guards refused to disclose why the trail had been closed.

“If they’ve got a toxic chemical down in the dirt, why are they keeping this so hush-hush?” he asked. “This is a state park bordering on several large communities. I think people have a right to know.”

Sugg said the spill is under investigation by state Fish and Game, the Orange County Sheriff’s Department and the state Regional Water Quality Control Board.

Sugg said the cleanup is time-consuming because of the thick vegetation that lines the narrow creek and canyon bottom. Sugg said officials want to preserve as much of the brush and trees as possible.

“We could take bulldozers and just level that area, and get that dirt out,” he said. “But that’s not the way to do it. We don’t want to disturb any more of the area than necessary.”