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San Diego May Get Quicker Water Quality Test For Beaches

Dennis Purcell finishes taking water sample at Tidepool Beach in Coronado on ...

Photo by Erik Anderson

Above: Dennis Purcell finishes taking water sample at Tidepool Beach in Coronado on Aug 8, 2019.

San Diego County regularly tests water at more than 45 beaches to make sure they are safe for swimming, wading and other recreational contact, and Dennis Purcell was making the rounds to collect those samples. On a recent day, he snapped a bottle onto the clip at the end of a long yellow pole waded out into the warm water at Tidepools State Beach.

“Well, I have to walk out approximately knee-deep. The reason I do this is because I want to get an accurate sample,” Purcell said.

Listen to this story by Erik Anderson.

Purcell methodically dips the bottle into the bay stopping just above an underwater carpet of eelgrass. He wraps the bottle in a plastic bag, drops the bag into a cooler and heads to another location. This is one of 90 spots where county and other municipalities regularly sample water to check if there’s pollution. But the current test may not be fast enough to protect people are the beach.

That’s why the county looking at a new way of testing the waters.

Reported by Erik Anderson , Video by Matthew Bowler

Testing is a a regular event

“Really our primary goal is to protect public health for swimmers, surfers, kids going to the beach,” said Lars Seifert who works at the San Diego County Department of Environmental Health. “We want to make sure that they know that water is safe when they go in to swim or surf or enjoy our recreational opportunities here at our San Diego County beaches.”

More than 90 locations get at least a weekly water test during the warmer summer months.

“We do conduct year-round testing as well so some of the more popular beaches, through the wintertime, we’re testing to make sure that we get that information to the public,” Seifert said.

The frequency of water testing declines in the winter when fewer people are in the water off local beaches. If water tests uncover pollution, the county will issue an advisory and post warning signs on the beach.

“We’ll continue to sample until we can make sure that and confirm that the water quality is meeting health standards and then we’ll basically lift that beach advisory,” Seifert said.

RELATED: South San Diego County Beaches Getting More Water Testing

The county currently uses a water testing method that involves culturing any bacteria that may be in the sample. Essentially, lab workers add food to a sample and wait a day to see what grows.

The samples are in sealed trays and workers use ultraviolet light to show the harmful bacteria.

Pollution warning signs only go up about 24 hours after the original sample was taken, meaning the threat may still remain or it may have passed.

A new faster test may change that.

San Diego County has been working with a new test for more than a year.

It is a process that essentially identifies partial DNA strands of dangerous bacteria and extrapolates how contaminated a water sample is. That can be done in a matter of hours.

Photo by Erik Anderson

Streeya Steele is testing a water sample in the San Diego County Public Health Lab on Aug 12, 2019.

“It is a little bit more technical so you have to be very good with your hands because we’re using very small pieces of equipment,” said Streeya Steele, the deputy director of the San Diego County Public Health Lab.

The new Polymerase Chain Reaction test does not require lab workers to wait for the bacteria to culture. The PCR test is faster and “It’s much more sensitive,” Steele said.

That conclusion comes after a year-long side-by-side study of the two testing methods.

RELATED: More Water Testing May Be Coming For Tijuana River Valley

The Environmental Protection Agency and State Water Board approved the test with an eye on seeing if the PCR test was effective. Both agencies would have to approve a switch to the faster test.

The Department of Environmental Health’s Lars Seifert said that could lead to same-day water quality test results.

“Take the sample, the water quality at the beach, have it to the lab and the same day before people who are visiting the beach, go out,” Seifert said. “They’d have that information on what the water quality is and whether it’s safe to surf or swim.”

San Diego County could find out by the end of the year if the new testing method is approved and becomes the standard.


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Erik Anderson
Environment Reporter

opening quote marksclosing quote marksI focus on the environment and all the implications that a changing or challenging environment has for life in Southern California. That includes climate change, endangered species, habitat, urbanization, pollution and many other topics.

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