San Mateo County beaches are the second-worst in California when it comes to a key measure of bacterial pollution, according to a report released Wednesday by the Natural Resources Defense Council.
Contra Costa County's beaches were the worst, the report found. But the sample size for Contra Costa County was small -- only two monitoring sites, the north and south ends of Richmond's Keller Beach, were included in the report. San Mateo County, meanwhile, contributed data from 45 sites at beaches on the bay and along the Pacific Ocean.
The beaches in these counties exceeded daily maximum levels for E. coli and other bacteria in 2012 more often than any other counties in the state, the report found. California ranked 20th of 30 coastal states, including those surrounding the Great Lakes.
Stormwater runoff and sewage spills are the primary causes of bacterial pollution on beaches, according to the Natural Resources Defense Council, which based its annual "Testing the Waters" report on water-quality data from more than 3,000 beach sites across the country. Citing a 2001 analysis by the U.S. Environmental Protection Agency, the council claims as many as 3.5 million Americans -- and possibly more -- become ill every year by coming into contact with pollution from these sources.
"Stormwater pollution remains a persistent problem on our coasts and beaches," said Noah Garrison, a California attorney with the council, "and it's certainly a problem we need to do more to address."
Keller Beach formed the basis for Contra Costa County's poor showing in the report. Two monitoring sites exceeded bacteria thresholds a combined 17.3 percent of the time.
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."
Other Bay Area beaches flagged for poor conditions in the report include Baker Beach and Candlestick Point in San Francisco and the portion of Alameda's Crown Memorial State Beach by the Elsie Roemer Bird Sanctuary.
San Francisco's violation rate was 15.1 percent, good for fourth in the state. Santa Cruz and Alameda counties ranked sixth and seventh in California, respectively, with rates of 10.5 and 10.1 percent. None of Santa Clara County's shoreline along the bay was included in the study.
A total of 5,515 beach closing and advisory days were issued last year at California's more than 430 beaches, a 5 percent decrease compared with 2011, according to the Natural Resources Defense Council. Ten percent of water-monitoring samples exceeded public health thresholds statewide. California counties vary in the scope and frequency of their water monitoring.
Cities ringing the bay have taken significant steps to decrease sewage spills over the past several years, thanks in large measure to San Francisco Baykeeper, a nonprofit that has filed a dozen Clean Water Act lawsuits to combat sewage pollution. The suits have forced more than 20 cities and sanitary districts to spend millions of dollars upgrading aging sewage systems to prevent them from getting overwhelmed during winter storms, causing untreated or partially treated sewage to be dumped into the bay.
One of the organization's first lawsuits, in 2006, targeted Richmond, which agreed in a settlement to perform a major overhaul. Overall most of the suits have been filed against operators of San Mateo County sewage systems, including Burlingame. Deb Self, executive director of Baykeeper, said sewage spills in the county are down as a result.
"The key issue up and down the coast is deferred maintenance," Self said. "Just forcing cities and sewage districts to invest funds on maintenance and repair has a direct impact on public health."
Larry Patterson, director of public works for the city of San Mateo, did not immediately respond to a request for comment about the problems at Parkside Aquatic Park and Lakeshore Park, whose beaches were shut down five days each in 2012. San Mateo County's director of environmental services, Dean Peterson, said in a statement that the county exceeds state requirements for water-quality testing to help ensure public safety.
Contact Aaron Kinney at 650-348-4357. Follow him at Twitter.com/kinneytimes.
A listing of Bay Area beaches and the rate at which they exceeded daily thresholds for bacterial pollution.
Alameda Crown Beach, 2001 Shoreline Drive -- 10 percent
Alameda Crown Beach, Bath House -- 6 percent
Alameda Crown Beach, Bird Sanctuary -- 25 percent
Alameda Crown Beach, Crab Cove -- 16 percent
Alameda Crown Beach, Sunset Road -- 7 percent
Alameda Crown Beach, Windsurfer Corner -- 4 percent
Contra Costa County
Keller Beach-North -- 18 percent
Keller Beach-South -- 16 percent
San Mateo County
Parkside Aquatic Park (San Mateo) -- 63 percent
Lakeshore Park (San Mateo) -- 46 percent
Pillar Point No. 7 -- 23 percent
Pillar Point No. 8 -- 17 percent
Pillar Point-Capistrano -- 52 percent
Pillar Point-Outer Harbor -- 15 percent
Source: Natural Resources Defense Council