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New San Diego ocean water testing much faster

San Diego County is using new, high-tech tests that will allow officials to test ocean water and find out if that water is safe for swimming, in just one day.

County supervisor Nora Vargas said the county is the first local government to get U.S. Environmental Protection Agency approval to use the new, sophisticated tests.

The switch is the culmination of years of testing.


Vargas delivered the news in Imperial Beach, a community that has been forced to live with sewage-tainted ocean crossing the international border and spilling into coastal waters.

The community’s beaches are posted as polluted an average of 200 to 300 days a year.

Imperial Beach Pier on May 4, 2022.
Erik Anderson
Imperial Beach Pier on May 4, 2022.

“The Tijuana River Valley pollution directly impacts the families of not only Imperial Beach but the community and the region as a whole,” Vargas said. “This advancement in water testing today is going to allow us to better monitor quality and provide us and the community with faster and more accurate information.”

The old tests relied on culturing water samples in a county lab for 18 to 24 hours. If bacteria grew in those cultures, local officials would know the water was not safe for humans.


The new test takes a different approach. The Digital Drop Polymer Chain Reaction test searches for bacteria DNA in samples — if officials find that genetic material, the water is unsafe. That test can be performed in four to six hours.

“If we can get those results back in, the same day as opposed to the next day, that means … potentially that people can go back into the water after a beach closure, more quickly,” said Wilma Wooten, San Diego County Public Health Officer.

San Diego County has regularly tested ocean water along the county’s 70 miles of coast since the 1990’s. Officials look for dangerous bacteria, like e-coli, which is a marker for sewage contamination.

Ocean water is tested more frequently in the summer because county officials do not want people swimming or surfing in polluted water that can cause problems for public health.

Testing results are published regularly and advisories are issued if there’s an area that fails to meet safe standards.