Lagoon Shellfish Show High Bacteria Count

A shellfish farming operation in Carlsbad’s Agua Hedionda Lagoon is being dogged by high levels of bacteria that may be from sewage discharged into the ocean by nearby treatment plants.

State health officials said high concentrations of fecal coliform bacteria have periodically been detected since late last year in shellfish being grown at the lagoon.

“This far exceeds the shellfish meat standards,” said Pat Wells, a state Health Services Department sanitary engineer. “You wouldn’t want to be eating shellfish with those kinds of levels in them.”

But the shellfish, which are sold by Carlsbad-based Seafarms West primarily to out-of-state wholesalers, are safe to eat because the firm flushes the oysters and mussels with fresh water for two days before marketing them, authorities say.

Shellfish are filter feeders, gathering nourishment by pumping up to 20 gallons of water each day through their systems, so 48 hours in fresh water cleanses their systems of any bacteria, Wells said.

“From our standpoint, it doesn’t affect our operations because all the shellfish we harvest are held on shore for a few days in tanks anyway,” said Dick Glenn, owner of Seafarms West.

Report to Be Issued

Nonetheless, state health officials are concerned about the high bacteria concentrations in Agua Hedionda and will issue a report to the San Diego Regional Water Quality Control Board within a month that should point the way toward solutions.

Among the potential actions the Water Quality Control Board might take would be to order the Encina and Oceanside sewage treatment plants to conduct an in-depth study or begin treating their effluent with chlorine to reduce bacteria.

The Encina plant, half a mile south of the lagoon, has been spotlighted as a possible source of the bacteria. The plant’s ocean outfall pipe pumps more than 20 million gallons of treated sewage a day into the sea about 1 1/2 miles from shore.

Encina officials argue that the bacteria may have been caused by animal fecal matter caught in runoff from the land, but state health officials say the high coliform counts have been concentrated toward the mouth of the inlet.

Although unsure of the exact causes, authorities suspect that a sudden ocean upwell prompted by a wind shift might have caused effluent to stream into the lagoon and affect the shellfish.

Rich Graff, Encina general manager, said a more in-depth study of the situation could cost up to $500,000. He had no estimates of how much it would cost to add the necessary facilities to begin chlorinating the treated sewage before it is pumped into the sea, but said such an addition to the plant would require “big dollars.”

“It could push us into a real estate problem here in terms of do we have enough land to do what would be required?” Graff said.

Despite the limited effect on shellfish harvesting at Seafarms West, Glenn is eager to see a solution.

“It’s kind of lucky that we’re here running this farm and taking water samples regularly,” he said. “It’s an early-warning system. This kind of thing can get nipped in the bud before it becomes a problem.”