Health Officials Keep Coast Closed : Spill: Bacterial counts remain low everywhere except at the tip of Point Loma, but quarantine will remain in effect through the weekend.

County health authorities reported another day of reduced bacterial counts Friday, but, despite the optimistic news, said they would continue to quarantine 20 miles of area coastline through the weekend.

For the fourth straight day, only the tip of the Point Loma Peninsula recorded readings of fecal coliform bacteria in excess of the legal limit as a result of the daily overflow of 180 million gallons of partially treated sewage.

Dan Avera, a spokesman for the San Diego County Department of Health Services, said the reading at the tip of Point Loma was 15 times the legal standard.

Otherwise, all other on-shore stations recorded readings well below the legal limit, which is defined by 1,000 coliform per 100 milliliters of water. Even Imperial Beach and the Silver Strand, near where raw sewage from Tijuana is overflowing, reported low readings once again.

But beaches extending from the international border to the mouth of the San Diego River remain under quarantine.

“We’re trying to get a better handle on what the currents are doing and what the plume of sewage is doing, and so far--barring a storm--it continues to move in a southerly direction,” Avera said. “Even in moving that way, however, it seems to be isolated right at the tip of Point Loma.”

The spill, discovered Feb. 2 by the Coast Guard, continues to spew 170 million to 180 million gallons a day of treated sewage--from which 75% to 80% of the solids have been removed--3,150 feet from the cliffs of Point Loma, at a depth of 35 feet.

Ordinarily, the sewage is discharged 2.2 miles at sea, at a depth of 220 feet, but the huge outfall pipe that carries it is ruptured in 22 sections three-quarters of a mile from shore. Earlier this week, divers discovered more damage near the one-mile mark, about 55-feet deep.

City officials said Friday that they hope to reopen on Monday a binational pump station that normally diverts 12 million gallons a day of raw sewage from Tijuana into the San Diego metropolitan system.

Heavy rains forced the closure of the pump station soon after the Point Loma spill, mixing the overflow of raw sewage with more than 100 million gallons a day of contaminated rain runoff from swollen creek beds and rivers.

That spill elevated bacterial counts to as much as 1,100 times the legal limits in Imperial Beach and Coronado, and all along the Silver Strand, during storms earlier in the month. City officials said Friday that the flow from Tijuana is now down to 28 million gallons a day.

In other spill developments, the city announced that two groups of scientists from Scripps Institution of Oceanography will assist in assessing the biological effects of the spill on the area’s kelp forests.

The scientists will examine how excessive sedimentation and reductions in sunlight in deeper waters of the kelp beds may have restricted growth.

Mia Tegner, a marine biologist at Scripps, said in a statement issued Friday that the kelp beds “shelter a rich community of marine plants and animals and are an important resource for sport and commercial fisheries and the kelp-harvesting industry.”