Oil Unlikely to Seep Into Water Basin : Environment: Officials say rainfall before the slick is cleaned up could still pose a threat to supplies west of Piru.

Crude oil from a broken pipeline in the upper Santa Clara River is not expected to seep into underground drinking-water supplies downstream unless heavy rains hit Ventura County before the eight-mile-long slick is cleaned up, county officials said Sunday.

Despite early fears that oil--which quickly spread from Valencia to Piru on Friday--might contaminate a series of ground-water basins, officials said it now appears unlikely that basins west of Piru will be affected.

“I don’t think it would ever get down here,” said County Supervisor John Flynn, referring to the Oxnard and Ventura areas, which are about 35 miles from the western tip of the slick.

There is a risk of oil-based carcinogens leaking into drinking water beneath the river near Piru, but even there “I think the risk is relatively low,” said Flynn, who specializes in water issues.

No tests have been conducted at wells near the oil slick to see if toxics such as highly poisonous benzene have already dissolved in the water and seeped through the sandy Santa Clara riverbed into drinking water, said Frederick J. Gientke, general manager of the United Water Conservation District. The district oversees the replenishment of subterranean basins from Piru to Oxnard.

Nor is the spill threatening drinking water for the Santa Clarita Valley in Los Angeles County because it occurred downstream from wells, officials said.

Gientke estimated that it would take three to five inches of rain in the next month to cause surface water to move at rates fast enough to flush the oil downstream.

Meanwhile, a spokesman for Mobil Oil Corp., which owns the ruptured pipeline, said a 175-person company crew recovered 35% to 45% of the 75,000 gallons of oil that leaked from an 18-inch-long crack near the Valencia Golf Course early Friday.

The slick has been contained eight miles downstream at the confluence of the Santa Clara River and Piru Creek near Piru, where the spill is 12 feet wide in some places.

Though Mobil is operating 21 large suction trucks, it will be several days before all crude oil on the surface of the river is removed and one to two months before the entire cleanup of shorelines and the riverbed is complete, spokesman Jim Carbonetti said.

He said there is no indication that the oil is sinking into the riverbed.

“The crude is staying on the surface of the water,” he said. “It’s very heavy crude. In fact, when we transport it in the pipeline we have to heat it.”

But the toll of the oil slick on fish and wildlife continues to mount, according to state Department of Fish and Game officers.

By late Sunday, 27 birds had been found dead and 67 others rescued. In addition, a muskrat and a fish were rescued, they said.

Ventura County officials said they will meet within three days with state and federal officials to plan how to determine the unseen effects of the oil slick.

Gientke said wells downstream from the western tip of the spill probably will be tested to see if hydrocarbons have moved into drinking water. Wells may also be drilled across the riverbed to pump out contaminated water and dispose of it, he said.

Three connected water basins that underlie Piru, Fillmore and Santa Paula supply at least part of the water for the cities of Fillmore, Santa Paula, Port Hueneme, Ventura and Oxnard, he said.

But Gientke and Terry Gilday, a manager in the county Environmental Health Department, agreed that much downstream contamination is unlikely.

Ground water moves so slowly--only a few feet a day--that even wells near the spill probably will escape contamination, Gilday said. Yet, he said he is concerned that several storms would carry the oil on the river’s surface downstream and contaminate Fillmore and Santa Paula wells.

“That is the biggest hazard,” he said. “The oil at the surface would be carried downstream into underground basins in a couple of hours. It would go like gangbusters and seep through the ground.”

The irony of the situation was not lost on Gientke.

“It is a contradiction: We were wishing hard for rain. Now it is just the opposite,” he said.

Times staff writer Philipp Gollner contributed to this story.