Will the Coronado, Imperial Beach shoreline be closed all summer? New test reveals massive Tijuana sewage


Coronado’s bustling coastal community and working-class Imperial Beach could be headed for a big reckoning if Tijuana’s sewage spills over the border.

Beach closures, once considered a massive winter phenomenon, are now poised to become a year-round phenomenon in San Diego’s South Bay.

But that’s not because cross-border pollution from Baja California’s overly burdensome and crumbling sewage system has increased dramatically, according to county officials.

This is because the ocean is more polluted than before. A flood of recently closed shorelines on May 5 sparked a nearly decade-long rollout of a new DNA-based water quality testing system.

“This method is more precise and accurate, allowing us to get a better picture of water quality,” said Heather Buonomo, director of the county’s Department of Environment, Health and Quality.

“Unless the root cause of this problem is addressed, which is the sewage pollution that flows to these beaches, this will continue,” she warned.

Coronado’s beaches have been closed for 17 days since new testing began early last month. The Imperial Beach shoreline to the south, hit hard by sewage pollution in the past, was immediately closed and has yet to reopen.

“No one expected this to result in a closure until after Coronado,” Imperial Beach Mayor Serge Dedina said Tuesday. “Right now our beaches will be closed all summer.”

Coronado Mayor Richard Bailey did not respond to multiple requests for comment.

Dedina and others expressed concern that the closures could have broader economic and social impacts, potentially affecting formwork programs and Navy training operations such as junior lifeguards and YMCA surf camps.

“The Hotel Del (Coronado Beachfront) is now continuously closed,” said Chris Helmer, Imperial Beach’s director of environment and natural resources. “It will upset a lot of powerful people.”

The Naval Special Warfare Command, which is based on the south end of Coronado and is the San Diego Navy SEAL training home, did not return a request for comment.

According to county health officials, closures are needed to protect beachgoers from dangerously high levels of bacteria and viruses. Swimmers who ignore the restrictions can risk diarrhea, fever, respiratory illness, meningitis and even paralysis.

San Diego is the first coastal county in the country to install a state-approved water quality testing system that uses DNA technology, officials said. The effort involved researchers from the US Environmental Protection Agency, the California Department of Health and Human Services and UC San Diego.

“We started this process nine years ago because we had heard loud and clear from the community that they wanted to know what was happening to their water,” said Buonomo of the county. “They wanted faster results and more accurate information about whether it might be making them sick.”

The older test system is the so-called culture extraction, in which scientists examine water samples in the laboratory for bacterial growth. Officials said the new DNA-based method is not only more accurate but also faster, delivering results in 10 hours instead of 24. In any case, the presence of bacteria is considered an indicator of pathogens such as E. coli, Vibrio and Salmonella.

“If you have a high rise in effluent in your sample, the culture method can often miss them, while they are not absent from a DNA test,” said Jeremy Corrigan, operations manager at the San Diego County Public Health Laboratory.

For years, environmental officials thought that the sewage that poured over the border from Mexico was largely the result of heavy winter rains, which carried polluted runoff and sewage through the Tijuana River Canal and into the mouth at Imperial Beach.

However, recent studies by UCSD’s Scripps Institution of Oceanography and Stanford University have identified an inactive sewage facility in Tijuana as the main source of pollution. The San Antonio de los Buenos Aires wastewater treatment plant in Punta Bandera dumps an estimated 35 million gallons of raw sewage per day into the Pacific Ocean.

When ocean currents move north, known as the “Southern Swell,” they can carry piles of sewage and other pollutants north as Coronado. According to health officials, such conditions are common in spring and summer.

The EPA has issued a $630 million bill, about half of which will be funded to help prevent transboundary pollution. A big part of the plan is to recycle most of the wastewater currently being pumped at Punta Bandera, which relies on the old lagoon system. Instead, this wastewater is sent to the South Bay International Wastewater Treatment Plant along the border in San Diego.

Staff writer Andrew Dyer contributed to this report.



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