Where to find beaches offering good clean fun

Northern California is home to some of the cleanest - and dirtiest - beaches in the state when it comes to water quality.

Venice Beach, one of several beaches that make up Half Moon Bay State Beach in San Mateo County, has some of the most tainted water in the state, earning it the designation "Beach Bum" by the Natural Resources Defense Council in a recent national report on water quality at popular swim spots.

Bacteria found in the water there violated public health standards in 57 percent of the 35 tests conducted in 2006, according to the report, which relied on data collected from the U.S. Environmental Protection Agency.

Swimming in water with high bacterial levels can increase the risk of becoming sick, including ailments like skin rashes, diarrhea and ear infections, health officials said. While most of these illnesses last for a matter of days, they can cause serious problems for children, the elderly and people with weakened immune systems.

Waterborne disease outbreaks sickened 2,698 people across the country, including 58 hospitalizations and one death, during a two-year period from 2003 to 2004, according to a 2006 report from the Centers for Disease Control and Prevention.

Half Moon Bay's Venice Beach had the worst rating in the report for a single beach in California. Longer beaches had their water sampled at multiple points along the coastline. One portion of Long Beach in Los Angeles County ranked worse than Venice Beach, violating health standards in 59 percent of the tests, but other stretches of Long Beach ranked much lower.

By contrast, 23 beaches along the coast from Monterey County to Sonoma County, and parts of three other beaches, had water that never exceeded public health safety levels during testing in 2006. That includes popular Drakes Beach at the Point Reyes National Seashore, the report shows.

What makes the difference?

Often, we do, environmental health officials said.

"Let's face it, humans have an impact on natural water," said Dave Smail, a supervising health inspector for Marin County's Environmental Health Services. "Anything washing off pavement in built-up areas, from animal waste to human waste, has an impact."

As a general rule, the more remote the beach, the cleaner the water, officials said. Marin, Santa Cruz and Sonoma counties each had at least five beaches that never exceeded public health safety levels in 2006, while every San Francisco beach violated the standards at least once, the report shows.

State water quality testing requirements for coastal beaches were extended in 2004 to include beaches along San Francisco Bay.

Thanks to the conservation group Save the Bay, Crown Beach in Alameda, one of the most heavily used in the Bay Area, now boasts upgraded signs with large red, yellow and green indicators - similar to a stoplight - to inform beachgoers about the water quality, rather than rely on text-heavy signs.

Water off Crown Beach exceeded safety levels between 5 and 28 percent of the time during testing in 2006, depending on where along the 21/2-mile beach the testing took place, according to the report.

Both wild animals and domesticated ones, particularly cattle, also play a role in fouled water, as do faulty sewage systems, contaminated runoff and urban development in coastal areas, according to the report and health officials.

Authorities in San Mateo County point to the hundreds of seagulls that make Venice Beach their home. Bird droppings are the major cause of that beach's poor water quality, officials said.

"It really is due to the bird population that is taking over Venice Beach," said Dean Peterson, director of San Mateo County's Environmental Health Division. "If you look at the creeks that empty down into Venice Beach, as you go up the watershed, we don't have a lot of septic systems, we don't have a lot of sewer overflows at those homes, so it does appear mainly to be the birds."

Problems with contaminated water also increase after a heavy storm. Pet droppings, rotting vegetation and other pollutants can wash into drains and flow unfiltered into the ocean. Likewise, some cities have inadequate sewage systems that may get overwhelmed by a major downpour.

"The larger the storm, the normal material that may not get into the storm drains then flows into it," Peterson said. "You're basically washing more off the streets and off the watershed."