As dead fish were being gathered for analysis yesterday, sewage officials started talking about prevention measures, such as installing more meters to provide early leak detection warnings at the lagoon that separates Oceanside and Carlsbad.

In this case, it appears the problem was reported Sunday evening by a passerby who smelled the sewage near Jefferson Street and Marron Road. When the leak actually started remains unclear.

Emergency repair costs hit about $250,000 yesterday. The total bill facing the cities of Vista and Carlsbad, which own the pipeline, will go higher after a late-afternoon decision was made to pump more than 10 million gallons of water from the lagoon south to the Encina sewage treatment plant. After it's processed, that water would be released into the ocean.

The 200-acre lagoon is a state ecological reserve managed by the California Department of Fish and Game. It's home to more than 100 species of birds, plus several varieties of fish and plants.

The ecological damage caused by the sewage spill will take weeks to unfold as the nutrient-rich sewage fuels algae growth, which steals oxygen from fish.

Yesterday, the lagoon remained ringed in neon orange signs that warned people to keep out of the water. Pungent odors wafted on the sea breeze as city crews and private contractors buzzed around the site.

A few workers floated on the greenish water taking samples. Others kept an eye on machines designed to aerate the lagoon. Still others replaced the faulty section of the 24-inch iron pipe.

Carlsbad leaders said the break appeared to be the result of corrosion but that the direct cause was still uncertain yesterday.

SEAN DuFRENE / Union-Tribune Nicole Woodward (left) and Esther Goldstein, watershed technicians for Weston Solutions Inc., performed dissolved oxygen-content tests at the lagoon. The tests will indicate the extent of the sewage plume.

“(There's) no indication that it was a sign of things to come,” he said.

He added that the break was not something that city officials could have prevented, short of digging up major stretches of pipe to look for weak spots. But that kind of work disturbs the environment and could damage the pipe as well.

“I don't exactly . . . know how we would have avoided this,” Pruim said.

Project costs will be shared by Vista and Carlsbad, which has taken the lead on the construction project.

However, Vista owns most of the ruptured pipe and likely will be liable for more than three-quarters of the cost. It has a relatively clean sewage-spill record since 2002, according to data from the San Diego Regional Water Quality Control Board, the lead regulator for water pollution.

SEAN DuFRENE / Union-Tribune Carlsbad city crews and contractors worked yesterday to replace the faulty foot-long pipe. The new pipe was repressurized by midafternoon.

The spill is part of a larger trend that some wastewater officials and environmentalists have dubbed a national crisis in sewage infrastructure. In Congress, wastewater agencies are pushing for $14 billion to beef up the country's sewage systems that are crumbling more quickly than they can be replaced.

At the Regional Water Quality Control Board, executive officer John Robertus said the most recent incident fit other regional trends.

“We are seeing fewer spills . . . but we still see these large spills infrequently and we are very concerned about this,” he said.

Robertus said pipes in lagoons are often problematic because they are exposed to lots of water, which increases corrosion. In addition, it can be difficult for utility managers to perform tests and make repairs near environmentally sensitive wetlands and canyons, he said.

In those areas, “we have seen a pattern of deferring maintainance and repair due to limited access.”

At the Buena Vista Lagoon Foundation, executive director Ron Wootton said the most recent spill was reminiscent of several others dating back decades.

“It has happened before and may happen again,” he said. “It's a function of having several main sewage lines serving three cities running through the channel upstream from the lagoon.”

Kimberly McKee-Lewis, senior scientist at the state Department of Fish and Game, said she was trying to put together a long-term plan to monitor the environmental effects of the sewage plume. She also encouraged utility leaders to find new safeguards – perhaps including rerouting pipes – to avoid similar incidents.

“Every time we get to this point (after a spill), it's the likely conclusion that some alternatives to having sewage go through and in a lagoon need to be found,” she said.

In addition to looking at options, Carlsbad and Vista will be watching the regional boards' penalty process. Based on a fine after a 34 million-gallon spill by the city of San Diego in 2000, the cities could be on the hook for 10 cents a gallon, or $500,000.

Robertus said it's too early to speculate about what his agency will do. “We don't have a formula,” he said. “It's not automatic.”