Sewer Break Tally at 4.5 Million Gallons : Foul-up: The spill into the San Diego River was reported but went untended for two days.

A broken sewer main that went untended for two days has spewed about 4.5 million gallons of raw sewage into the San Diego River, city water officials said Tuesday, conceding that repairs have not been timely because communications broke down as well.

The break was caused by last week’s storms, which eroded the ground supporting the 21-inch-diameter main, just north of Interstate 8 on a Del Cerro hillside, water officials said. County health officials posted warning signs along the river west to the ocean, at Dog Beach.

Water officials said Tuesday that the nature and timing of the spill could not have been worse.

Though even significant spills are not uncommon--there were two just last month, one in Mission Bay, one in Fallbrook--this spill is one of the largest in years. And it erupted Saturday, all of one day after a San Diego federal judge fined the city $3 million for a pattern of inadequate sewage treatment that violated federal clean-water laws.

Water officials stressed Tuesday that a storm-damaged sewer main is rare and is absolutely unrelated to the court case, which dealt with the 190 million gallons of treated sewage that the city pumps daily into the ocean off Point Loma. But the irony was keenly felt.

“It is just the timing--that’s clearly a problem,” said Daryl Grigsby, deputy director of the city Water Utilities Department. “When was the court decision? Last Friday. Then this happens the next day. That’s a problem.”

Grigsby said it is unclear how the spill, in Alvarado Canyon near the 5600 block of Adobe Falls Road, went untended until Monday. A homeowner on the block reported the spill Saturday, but, inexplicably, nothing was done about it until the homeowner called back Monday to say the sewage was still gushing, Grigsby said.

It is uncertain whether dispatchers did not report the call to crews or crews simply did not act on the call, he said. City officials planned to interview the radio dispatcher and all of the field units and will listen to dispatch tape, Grigsby said.

“The thing we know about that is that it was called in (by the homeowner) as a leak in the canyon,” Grigsby said. “We probably get, I don’t know, 10, 15 leak calls a day, maybe more. A lot of it is irrigation runoff, a lot is storm runoff. Sometimes it’s a water main break.”

“Basically, the investigation never occurred on Saturday,” he said. “Why that is, we still don’t know. We’re still looking into it.”

The result was that, for two days, sewage tumbled down the hillside at 1,200 gallons a minute, Grigsby said. The 21-inch-wide main is a so-called trunk line; it gathers sewage from the 8-inch pipes that service the city’s homes and eventually delivers it to the Point Loma treatment station, he said.

After the second call Monday and the discovery of the spill, repairs were still delayed because crews had to build a road up the canyon to get to the main, Grigsby said.

By Tuesday afternoon, crews had built a dirt berm that stopped the spillage by redirecting it back into the pipe a few feet farther down the line, he said. “But since this is basically a dirt berm system we’ve got, there’s a possibility we could have partial overflows,” Grigsby said.

Crews were stationed to monitor the site overnight, he said.

It was not immediately clear when repairs would be completed. Grigsby said water officials hoped to finish the job in a week.

The pipe broke because the ground supporting it was washed away in last week’s series of storms, leaving the main suspended and unsupported, Grigsby said. Two 3-foot sections of pipe broke, he said.

Gary Stephany, deputy director of the county’s Environmental Health Services, said Tuesday that crews from his office had already begun testing water samples, aiming to open the river to fishing and the beach as soon as possible.

“Some of the results that we’ve had is that the bacteria drops off rapidly between Ocean and Dog beaches,” Stephany said. Dog Beach is at the far north end of Ocean Beach, just south of the Mission Bay jetty. “And on the north side of the Mission Bay jetty, we don’t have a problem.”

The beach will remain closed to swimmers and surfers until it passes swimming standards for two straight days, Stephany said. Signs warning of the threat of contamination in the river were posted at the popular fishing spot near the foot of Rainier Avenue.

A March 1 sewer break led to a spill of 492,000 gallons into Mission Bay. A break discovered March 6 in Fallbrook reportedly may have spilled 600,000 gallons into the San Luis Rey River, according to the Rainbow Municipal Water District.

The worst sewage spill in San Diego County occurred in early 1987 when 20 million gallons of raw sewage spilled across Torrey Pines State Beach and into the ocean after the breakdown of a Sorrento Valley pumping station.

Times staff writer Russell Ben-Ali contributed to this story.