Waters Deserted After Sewage Spill : Environment: Swimming is banned along 15 miles of shoreline stretching from Mexico to San Diego after Tijuana pumps 25 million gallons of raw waste into the ocean.

Beaches normally jammed with summer vacationers were virtually deserted Thursday after a Tijuana sewage spill prompted health officials to ban swimming along a 15-mile stretch of beach north from the U.S.-Mexico border.

The closure affected beaches from Imperial Beach to Coronado and drew new attention to the pollution generated by Tijuana, where population growth has far outpaced the Mexican border city’s ability to process sewage.

The San Diego County health services department imposed the ban after Tijuana shut down its sewage treatment facilities for maintenance Tuesday, diverting 25 million gallons of raw sewage into the Tijuana River. The river originates on the Mexican side of the border but empties into the Pacific Ocean on the U.S. side.

Northward ocean currents caused the sewage to “plume” toward U.S. beaches, said Gary Stephany, assistant director of San Diego County’s health services department. The untreated sewage presents swimmers with a risk of hepatitis and various gastrointestinal diseases, he said.

Tijuana sewage treatment facilities were repaired and back on line late Wednesday night. But the swimming ban will remain in effect at least through today and perhaps until next Thursday, depending on the strength of toxic bacteria in samples taken from ocean waters.

“It’s like a wasteland out here,” said Bryan Schultz, a lifeguard at Silver Strand State Beach just south of Coronado, describing his near-empty beach on an otherwise perfect day for beach-going.

“It’s sunny, breezy, a little bit of surf, and nobody’s in the water,” said Coronado lifeguard Steve Parker. “I’m just waiting for the health department to give me a call to open it up.”

A spokeswoman for the oceanfront Hotel del Coronado noted that the ban does not prohibit walking along the beach or sunbathing and that it was business as usual for the hotel.

Although occurring regularly over the last decade, sewage spills have become more frequent as Tijuana’s population has mushroomed, said David Schlesinger, director of the San Diego Metropolitan Wastewater Department.

And whereas spills once happened mainly during the winter rainy season, they can occur anytime now. Most recently, a Tijuana sewage main burst in May, sending 25 million gallons into the ocean and causing beach closures on the U.S. side.

Even under normal conditions, Tijuana dumps 3 million gallons of raw sewage a day into the Pacific, Schlesinger said.

Site work is finally slated to begin this month on a new $239-million sewage treatment facility on the U.S. side of the border designed to treat 25 million gallons of Tijuana waste water daily. Vice President Al Gore is scheduled to speak at the July 15 groundbreaking of the project jointly financed by the United States and Mexico.

The project could be completed by late 1995, said Bill Ruth, project manager of the International Boundary and Water Commission, which is planning the facility in conjunction with the U.S. Environmental Protection Agency.

But construction of the plant may be slowed by a lawsuit filed earlier this year by the Sierra Club that seeks additional environmental impact reports and alternative site studies before construction proceeds.