For the third straight year, Los Angeles County had the worst overall beach water quality in the state, including five of the 10 lowest-rated beaches, according to the 18th annual Beach Report Card prepared by the environmental group Heal the Bay.

According to the report, Los Angeles County did show some improvement, with 71 percent of its beaches receiving positive grades of A or B, as opposed to 57 percent last year. But the county still had the worst water quality in the state, mainly due to major water quality issues in several Long Beach locations, Heal the Bay reported.

The group noted that one of the reasons Los Angeles County lags in water quality is the fact that its monitoring agencies collect samples directly in front of flowing storm drains and creeks. Several of the county's beaches that ranked among the worst in the state, however, are not near storm drains, including Avalon Harbor, Cabrillo Beach and several in Long Beach.

Meanwhile, 92 percent of Santa Monica Bay beaches received A or B grades during the dry weather months, an improvement over the past two years.

Overall, California overall had the best dry-weather beach water quality on record during 2007-08, according to the Beach Report Card.

Of the 517 statewide beaches in the survey, 93 percent received grades of A or B during the high-traffic summer beach season -- an 8 percent improvement from the previous season.

The group attributed the record-low winter rainfall in Southern California to providing the generally improved water quality. Only 29 beaches, or 7 percent, received D or F grades across the state.

"The Report Card is great news for the millions of people that visit California's beaches each year," said Mark Gold, president of Heal the Bay. "But it also demonstrates that stormwater pollution was as bad this winter as it was a decade ago. Local governments have a long way to go before making beaches safe year-round."

The worst 10 beaches in the state, according to the report, were:

-- Avalon Harbor Beach on Catalina Island;
-- Santa Monica Municipal Pier;
-- Poche Beach (Orange County);
-- North Beach Doheny (Orange County);
-- Marie Canyon Drain at Puerco Beach;
-- Cabrillo Beach harborside;
-- Long Beach, multiple locations;
-- Campbell Cove State Park Beach (Sonoma County);
-- Clam Beach County Park near Strawberry Creek (Humboldt County); and
-- Pismo Beach Pier (San Luis Obispo County).