The City of Coronado has utilized two different methods for testing the water quality off its coastline ever since San Diego County implemented a new form of testing, droplet digital polymerase chain reaction (ddPCR), two years ago.
According to Mayor Richard Bailey, in addition to ddPCR, which tests for fecal indicator bacteria DNA, the City of Coronado continues the traditional culture-based sampling after the county stopped doing side-by-side comparison testing.
“We as a city decided that it was important in the effort to make sure that we have good data to determine policy by and to inform our residents and guests as to whether or not the water is truly safe or truly not safe,” said Bailey.
Bailey said the city contracted with a company, currently Mikhail Ogawa Engineering, that has the laboratory and expertise to conduct water quality tests. Months of data have been collected for a report, which the city expects to roll out in the next couple of months.
“The city’s objective is to make sure that our residents and our visitors have accurate information to determine…whether or not our waters are safe to go in or not,” said Bailey, who said he personally feels comfortable entering the water at Coronado’s beaches.
The introduction of ddPCR
When ddPCR testing was first implemented in 2022, the county website noted that in the first few months afterwards, beaches in the South County waters had levels of bacteria exceeding state health standards.
For example, the new data resulted in 25 of 31 days of beach closures for Imperial Beach in May of 2022, compared to none in May 2021, according to the county’s Beach and Bay Program website. Meanwhile, the Silver Strand beach was closed for 16 of 31 days in May of 2022 compared to zero in May 2021. And Coronado’s shoreline closed for 11 days in May of 2022, another increase from zero days in May of the previous year.
Imperial Beach and Coronado previously brought ddPCR to the forefront when they urged the county to return to the previous culture-based testing, according to reports by Voice of San Diego in July of 2022, following closures and a new “warning” tier.
Bailey said Coronado beaches were closed roughly 30% to 40% of the time from May through the end of June in 2022.
“When we raised the side-by-side comparison discrepancies with the county, that’s when the county changed their closure policies…even if there is an exceedance of this new water quality test, the beaches won’t necessarily be closed, they’ll simply be under advisory,” added Bailey. “To me, that sends a really mixed message that’s very difficult to communicate to the general public and that ultimately kind of endangers the public health.”
Frequent closures and liftings for Coronado beaches
In July, Coronado saw water contact closures lifted after the county said recent water-quality samples met state health standards at North Beach and the Coronado Lifeguard Tower.
Times of San Diego reported that beaches from the International Border through Avenida Lunar in Coronado remained closed due to sewage and increased risk of illness.
On July 24, virtual red pins indicating closures lined the entirety of Imperial Beach and Coronado shorelines on the county’s website. Two days later, Coronado’s North Beach and Lifeguard Tower appeared without red pins. The following week, Avenida Lunar was also considered safe for recreational use.
The last Sunday in July welcomed crowds of beachgoers between Coronado’s Avenida Lunar and the Lifeguard Tower.
Jayson Summers, Fire Chief for Coronado Fire Department, said lifeguards advise the public to follow health orders issued by the San Diego County Department of Environmental Health and Quality.
“In addition, we direct people to the County water quality webpage at www.sdbeachinfo.com,” wrote Summers in an email.
