EARHQUAKE / The Long Road Back : Waste Water Adds to River’s Problems : Environment: Valencia plant pours millions of gallons into oil-polluted Santa Clara.

The Santa Clara River, already assaulted with 168,000 gallons of crude oil from a pipeline ruptured in Monday’s earthquake, was furthered imperiled when sewage treated with chlorine poured into the river, officials said Wednesday.

About 6 million gallons of treated sewage from the Valencia treatment plant with added chlorine has poured down storm drains into the Santa Clara River and into Ventura County almost to Piru since Monday, officials said.

Chlorine, which is added to waste water to kill bacteria, is toxic to wildlife and is usually removed before the treated sewage is released into the river. The earthquake may have damaged a system that removes the chlorine before it is discharged.

However, officials said they also purposefully left the chlorine in the water to guard against any possible health and safety problems to humans because the waste water was not as highly treated as it usually is. The concentration of chlorine in the river does not pose a danger to humans, officials said.

“We didn’t dechlorinate because we were operating in an emergency situation,” said Jim Stahl, assistant general manager for the Sanitation Districts of Los Angeles County, which runs the Valencia plant. “We wanted to err on the side of human safety.”

Meanwhile, earthen berms built by workers on Tuesday were restricting the oil spill to a 12-mile stretch of the river just east of Piru, said Mary Gale, spokeswoman with the California Department of Fish and Game’s office of oil spill prevention and response.

But forecasts of up to one half of an inch of rain this weekend threatened to spread the spill farther downstream, Gale said.

“That would carry the oil beyond the berms and affect a greater stretch of the river,” she said.

By Wednesday, workers had vacuumed up about one-third of the oil, but the cleanup effort was expected to continue for weeks or months as contaminated soil is removed. Wildlife officials will write a plan to restore the damaged habitat.

The spill contaminated a stretch of the river that supports at least two endangered species, the tiny songbird least Bell’s vireo and the unarmored three-spined stickleback, a fish that dates from prehistoric times.

The first of the oiled wildlife began appearing Wednesday, but rescue workers stayed on the shorelines to avoid contact with the oil and chlorine, Gale said.

“As the animals get cold and stressed, they will come to higher ground where the rescue workers can reach them,” she said.

Wildlife officials had no count Wednesday of the number of birds that were affected. But International Bird Rescue of Berkeley, whose workers only recently returned home after the Christmas Day oil spill at McGrath Lake, was called to the scene.

Fish and Game’s mobile bird-cleaning trailer returned to the Ventura County animal shelter at the Camarillo Airport to begin cleaning and rehabilitating the animals. No birds had yet been brought to the shelter Wednesday.

An oil spill in the same area in 1991 killed 186 birds.

A spokesman for Arco Oil, the parent company of pipeline owner Four Corners Pipeline Co., said that company efforts were focused on the cleanup and that they had not yet had time to determine why that particular section of the 130-mile pipeline ruptured during the earthquake.

He estimated that it would be a full month before service is restored to the 10-inch pipeline that carries crude oil from Kern County to oil refineries in the Long Beach and Los Angeles areas.