Sewage Closes Beaches : Pollution: Heavy rain forces L.A. sanitation officials to dump 4 million gallons into Ballona Creek.

Los Angeles County health officials Friday ordered the closure of all Santa Monica Bay beaches from Pacific Palisades to the Palos Verdes Peninsula until at least Monday after 4 million gallons of partially treated sewage flowed into the bay.

Lifeguards posted yellow and red signs warning swimmers and surfers to stay out of the water from Topanga Canyon to Malaga Cove after heavy rain forced city sanitation officials to dump the partially treated sewage into Ballona Creek late Thursday night and early Friday.

The spill was the largest since a massive discharge of more than 60 million gallons during last February’s floods, which closed beaches for up to 11 days.

Jack Petralia, director of environmental protection for the county Health Services Department, said the beaches will remain closed until bacteria counts in the water drop to safe levels.

“If we have another big storm, I don’t see the counts dropping until 24 to 48 hours after that storm goes through here,” he said. “It could be Monday or Tuesday.”

In the meantime, Petralia warned the public to avoid contact with bay waters. “Sewage polluted water creates a health risk. That’s why we closed the beaches. The available evidence indicates that if you swim in sewage-polluted water you can get ill.”

After rainstorms, Petralia also urged beach-goers to avoid contact with the water within 100 yards of storm drains that flow into the bay.

The environmental group Heal the Bay said the latest spill poses “a significant threat” to the marine environment and to swimmers.

“No one should be going into the bay until Monday,” said Mark Gold, the group’s staff scientist. “Four million gallons is definitely a lot of sewage.”

City officials said the spill was caused when heavy rain overloaded the city’s aging north outfall sewer line, which carries waste water from as far as the San Fernando Valley to the massive Hyperion Sewage Treatment Plant near Playa del Rey.

Hyperion plant manager John Crosse said the 4 million gallons were diverted to a treatment facility in Culver City where it was partially filtered and chlorinated before being dumped into Ballona Creek, a major channel to the bay.

Although the city last summer dedicated a new $115-million north outfall replacement sewer to handle a greater volume of waste water, Crosse said officials decided last month to take the line out of service.

He said that the new sewer can carry up to 850 million gallons a day during a major rainstorm. But extensive improvements to the Hyperion plant have not been completed and the facility cannot process more than 680 million gallons a day in peak periods.