Ocean Beach in San Francisco (Molly Samuel/KQED)
Ocean Beach in San Francisco (Molly Samuel/KQED)

On Wednesday the National Resources Defense Council released a report on the water quality of beaches all around the country. It starts out with this pleasant thought: “The water at your local beach might be contaminated by human and animal waste, putting your health at risk: bacteria, viruses, and other pathogens in that waste can make exposed swimmers sick.”

Anything that leads with the words “contaminated” and “human and animal waste” is bound to get your attention. Here is the report’s interactive map for California. Scroll down to see a list of how each beach fared by county. The data include the number of days each was closed or an advisory was issued in 2012. The NRDC says the vast majority of these instances were due to unknown contamination sources. Sewage spills or leaks and stormwater runoff were also implicated.

According to the California Environmental Protection Agency, when an actual closure is ordered, “there has been a sewage discharge that is affecting the beach area. Closures are put in place immediately after a sewage spill is reported that may affect the beach.”

But there is a significant delay between the time a beach is determined to be too contaminated to use and when it’s shut down, the NRDC says. “Currently approved methods for determining levels of fecal indicator bacteria in beachwater depend on growth of bacteria colonies in cultures that take 18 to 96 hours to produce results. Because of this delay, swimmers generally do not know until the at least the next day if the water they swam in was contaminated. The delay also means that beaches may remain closed or posted after water quality has improved.”

The Bay Area was well represented in terms of bacteria that exceeded California’s daily maximum standards for exposure. According to the report, among the nine area counties, Contra Costa had the highest exceedance rate in 2012,  followed by San Mateo County. San Francisco was No. 4 at 15 percent.


Which California beaches are the most contaminated?
Which California beaches are the most contaminated?

In terms of closure or advisories, San Mateo County beaches topped the Bay Area list,  with Lakeshore at No. 1, if you want to call it that. The NRDC says that some counties, including San Francisco, Alameda and Contra Costa, monitor beachwater year-round, which ups their totals, but San Mateo isn’t in that group. The Bay Area News Group took a closer look at the data for the Contra Costa and San Mateo county beaches. From the article …

San Mateo County had a far greater data sample, but its 16.5 percent violation rate was driven by a trio of chronic offenders in terms of water quality: Parkside Aquatic Park and Lakeshore Park, two lagoon beaches in San Mateo, and Pillar Point Harbor north of Half Moon Bay.

One segment of the beach at Pillar Point Harbor had some of the highest violation rates in the state. Pillar Point-Capistrano, measured twice a month, exceeded public health standards for bacteria 52 percent of the time in 2012.

Sabrina Brennan, a member of the San Mateo County Harbor District board, said fecal contamination at Pillar Point is a long-standing issue, and a study on the subject is wrapping up. Brennan said she advises people not to let their children play at the Capistrano segment.

“There are other beaches,” Brennan said. “Go to a different beach.” Full article

Or you can wear your wet suit covered in Saran Wrap.

Find Out Which Bay Area Beaches Are Contaminated With the Most Bacteria 27 June,2013Jon Brooks

  • SD

    Thanks for sharing this important report, and linking to the Bay Area News group’s coverage. It would be nice if both the report summary and the article here could provide some clarification over what kind of pollution is being measured. “Bacteria” is an overbroad category. One would hope that the beaches are full of bacteria—something would be seriously wrong if the ocean water *wasn’t* full of bacteria. Presumably *Certain kind* of pathogens (bacteria, viruses, and other parasits) were tested for, and more information on that methodology and how they were chosen etc would be really helpful. Otherwise some may dismiss this report as fear mongering (which I’m sure it’s not). Thanks!

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