A Sewage Creep-Back Effect

Partially treated sewage released daily four miles offshore is creeping back toward Huntington Beach, Orange County Sanitation District scientists said Thursday.

District tests Nov. 27 revealed a finger-shaped plume of sewage pointing to a power plant on the city shore, about 1 1/2 miles off the coast. The tests also uncovered surprisingly high bacteria levels right off the beach in the afternoon--when tests haven’t been previously conducted.

Sanitation officials have been on the defensive since UC Irvine scientists in November released a study theorizing that the AES Corp. power plant in Huntington Beach might be drawing back sewage as it pulls in and releases ocean water to cool its equipment. About 240 million gallons of sewage is released from the sanitation district’s “outfall” pipe four miles offshore each day into the ocean.

Stanley Grant, the lead author of the UCI study, said the sanitation district’s findings “are quite significant. Their study makes our hypothesis more credible.”

But George Robertson, a senior scientist for the sanitation district, said the tests uncovered no evidence that the sewage actually reached the beach, and that some of the findings seem to be in conflict with the UCI study.

“The ability for the plume to get to the shore still isn’t there,” said Robertson. “It was a little closer than we’ve seen before.”

Another sanitation official acknowledged that on the day the tests were conducted, the power plant was undergoing maintenance and pulling in only about 2,000 gallons of ocean water, rather than the usual 300 million gallons, which presumably could have drawn any such plume even closer to shore. Huntington Beach city spokesman Richard Barnard said the sanitation district’s findings were far from complete.

“All of that has to be discounted on a winter’s day when the power plant wasn’t even operating,” Barnard said. “This test showed that there is something possibly going on. They need to do a thorough analysis.”

Before the UCI results, sanitation officials generally scoffed at suggestions that sewage discharged miles offshore might be migrating back to the coast. Researchers began studying the ocean waters after county, city and state officials were baffled by high fecal bacteria levels that closed miles of Huntington Beach’s shoreline for most of summer 1999.

Also on Thursday, Huntington Beach city officials began testifying before the county grand jury, which is investigating whether they withheld information that summer about the extent of sewage leaking from aging pipes inside the city. City officials insist that the leaks within the city had nothing to do with the shoreline closures in 1999.

Experts are still struggling to pinpoint the source of that summer’s ocean pollution.

Orange County is one of three agencies in Southern California that has a waiver from the federal Environmental Protection Agency that allows the release of minimally treated sewage into the ocean. In addition to Orange County, the cities of San Diego, and Goleta near Santa Barbara, have federal permission to release minimally treated waste. The city of Los Angeles and Los Angeles County remove more solids before sending human waste into the ocean.

Scientists have long thought that the topography of the coastal shelf off Huntington Beach, the direction and speed of currents, and a temperature inversion layer--called a thermocline--acted as a trap to keep the sewage plume several miles offshore. But the UCI study raised troubling new questions about whether subsurface waves are carrying sewage from the plume back toward the beach.

Sanitation district scientists who conducted the tests in November were also surprised to find an afternoon spike in fecal bacteria in waters lapping the beach.

“It is just some confounding information,” said Charles McGee, a microbiologist with the sanitation district, who said the bacteria near the beach did not come from the plume. “We’ve already decided that we will add a second survey in the afternoon, at low tide.”

Health officials for years have tested beach waters early in the morning, long thought to be a peak time for bacteria, before sunlight could burn it off and bathers entered the water.

Sanitation district officials will conduct more extensive water tests Wednesday and begin regular tests in April, when the ocean thermal inversion layer normally establishes itself. The tests will last through the summer, estimated to cost $500,000 to $1 million. The district also plans to put instruments on semi-fixed buoys to conduct round-the-clock measurements.

“We’re going to be doing a lot of work out there,” said Lisa Lawson, spokeswoman for the sanitation district.

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Pollution Plume

Water samples taken on Nov. 27 showed that sewage from the plume of wastewater deposited 4 miles offshore had moved back toward the coast in a finger-shaped pattern.

Source: Orange County Sanitation District.