Lake Restrictions to Stay : Pollution: County health officials are searching for ways to reduce high levels of bacteria found in Castaic Lake.

Restrictions imposed this summer on weekend use of Castaic Lake, one of the region’s largest boating and swimming facilities, will remain in effect indefinitely as the county explores ways to reduce the bacterial level in the lake’s four designated swimming areas, county officials said Tuesday.

“You just can’t ignore it,” said Brian Roney, assistant superintendent of the lake, referring to water quality tests indicating that on weekends, when the lake’s shallow swim areas are crowded, the water is unhealthy. The weekend tests, conducted since July, detected high levels of bacteria, which can cause diarrhea and fever.

The perimeter of the Castaic Lake swim area, about 10 miles north of Santa Clarita, will remain fenced on weekends to keep out walk-on visitors, Roney said. And the number of weekend swimmers will continue to be limited to about 800, he said.

Boating activities, however, are not affected by the swimming restrictions.

The restrictions at the county-operated lake have been in place since July 27. Earlier that month, tests by the Department of Health Services found, for the first time in eight years, that the bacterial levels in Castaic Lake’s swimming areas had climbed to unsafe levels.

Health Department officials stressed that there have been no reports of human illness as a result of the bacterial levels, and said the restrictions on the use of the lake are precautionary. They said drinking water, supplied by an adjacent 2,235-acre reservoir separated from the lake by a dam, is not threatened by the bacteria.

Although tests Aug. 19 and Aug. 26 found safe bacterial levels, the county Department of Parks and Recreation closed the lake’s swim areas during the busy Labor Day weekend anyway.

The weekend tests showed that bacterial levels in the swimming area were unsafe, even though tests done during the week indicated no problems, said Ralph Lopez, the county’s deputy of environmental health.

As a result of the troubling test results, he said, the Parks and Recreation Department installed additional portable toilets around the lake and instituted the weekend restrictions.

The county began routinely testing Castaic Lake on weekends only this summer, said Russ Johnson, an environmental health specialist for the Health Services Department. He acknowledged that weekend bacterial levels at the lake might have been unsafe in the past.

“It’s a good question that has come up now and then,” he said. “In the summer, in times past, we never really knew.”

County officials believe the rising bacterial levels reflect increased use of the lake by swimmers, not contamination from animals or a leak in the sewage system, Roney said. Last year, 1.5 million people visited the lake, compared with 900,000 in 1986, he said.

The county previously closed the lake’s swimming areas for much of the summer of 1982 because of high bacteria levels, Roney said. The Parks and Recreation Department hired a consultant, at a cost of $30,000, to identify the cause of the problem and ways to solve it.

The consultant determined that the problem was caused by people using the lake and animals emitting waste into it, not by a sewer leak, which would have been simpler to rectify, he said.

After the county installed a submerged aerator to circulate water throughout the lake, weekday tests showed safe levels of bacteria, Roney said.

Another cause of the lake’s high bacterial levels might be the region’s continuing drought, said Cal Miller, an environmental health specialist for the department. The lack of rain has made the state, which owns the adjacent reservoir, reluctant to release water into the county-owned lake, he said.

Thus, bacteria in the lake have not been flushed out.

The restrictions on weekend use of the recreational lake have rankled area merchants, who depend on the summer season--especially on holidays such as Labor Day--for much of their business.

“I want to make sure that they’re not screaming wolf,” said Jeff Preach, vice president of the Castaic Chamber of Commerce, referring to county officials.

He said local businesses have complained to him about the weekend restrictions.

As merchants complain and many weekend swimmers stay dry, county officials are exploring ways to solve what they expect will continue to be a problem at the lake’s beaches, due to close for the summer Sept. 22.

One option, Roney said, is to install a second underwater aerator in the lake, at a cost of $30,000.

Another is to dig up the sand under the swimming areas and lay a system of pipes to inject chlorine into the water during periods of high use.

The pipes would cost up to $100,000 to install, he said, and the chlorine needed for an average weekend would cost $1,500.

A third possibility would be to install a system that takes oxygen from the air and turns it into ozone, a nontoxic chemical that fights bacteria, blowing out the ozone underwater.

But that system, which would cost roughly $50,000, worked poorly in a recent test at the lake, Roney said.