San Diego County beaches scored high marks in the 2009 End of Summer Beach Report Card released Wednesday by environmental group Heal the Bay.
The group says most California beachgoers basked in a third consecutive summer of excellent water quality.
The group assigned an A to F letter grade to 458 beaches along the California coast, based on levels of bacterial pollution reported from Memorial Day through Labor Day.
San Diego County scored top marks, with 78 of 79 monitored beaches winning an A or B grade.
The county has completed numerous storm drain diversions into its sewage systems during the busy summer months, spurring a trend of steadily improving marks over the past five years.
The only dark spot this summer was Pacific Beach Point, which received an F grade.
Heal the Bay says 92 percent of sites in the state received A or B grades during the high-traffic beach season last summer. The grades are slightly better than last year, when 91 percent of beaches received high marks.
California's persistent and ongoing low rainfall totals, which limit polluted urban runoff in storm drain systems, play a major role in better water quality. Enhanced infrastructure at several sites also led to rising grades.
There were only 36 locations in the state, roughly 8 percent of all graded beaches, that received fair-to-poor water quality grades. Some 21 beaches received failing grades statewide.
The Beach Report Card is based on the routine monitoring of beaches from Humboldt County to the Mexican border by local health agencies and dischargers. Water samples are analyzed for bacteria that indicate pollution from numerous sources. The better the grade a beach receives, the lower the risk of illness to ocean users.
"Record low rainfall has helped maintain great water quality at the vast majority of California's beaches for the third summer in a row," says Mark Gold, president of Heal the Bay. "But we can't become complacent in our efforts to improve water quality in the summer season. We need long-term funding for beach monitoring and to ensure that problem beaches are safe for swimming every summer."
Los Angeles County once again had some of the lowest summer grades in the state, with only 80 percent of its 81 beaches receiving A or B marks. This year, 10 beaches in the county earned F's during the summer, but that marks improvement from last summer, when 19 percent of sites received failing grades.
The group says Orange County enjoyed excellent water quality this summer, with 102 out of 103 monitored beaches registering an A or B grade.
