Los Angeles County had the worst overall beach water quality in California last year, with six beaches, including at the Santa Monica Pier, selected among the worst “Beach Bummers” in the state, according to the environmental organization Heal the Bay’s 19th annual Beach Report Card.

The Beach Report Card is a comprehensive evaluation of coastal water quality based on daily and weekly samples taken from sites along the entire coast of California.

Under the report, Heal the Bay analysts assigned A-to-F letter grades to 94 beaches in the county for the dry-weather period from March 2008 through April 2009, based on levels of weekly bacterial pollution.

A poor grade means beachgoers face a higher risk of contracting illnesses such as stomach flu, ear infections, upper respiratory infections and skin rashes than swim- mers at cleaner beaches. Seventy percent of sites earned A or B grades, a state-low total for the fourth year in a row and nearly even with last year’s 71-percent tally.

Approximately 15 beaches in the county received year-round F grades, with six of them ranking in the annual Beach Bummer list of the most polluted sites in the state. Avalon Harbor on Catalina Island was listed as the worst Beach Bummer, while the Santa Monica Pier ranked fifth.

Overall dry-weather water quality in Los Angeles this year fell slightly below the county’s five-year average. Heal the Bay officials said a handful of chronically polluted beaches in Malibu, Santa Monica, Avalon and Long Beach contributed to the drop in the county’s overall grades.

“With summer coming, the state has made assurances that it will start restoring funding to beach monitoring programs, but there is no firm date,” said Mark Gold, president of Heal the Bay. “Until then, swimmers in many locations in greater Southern California are truly swimming at their own risk.”

One of the reasons that Los Angeles County lags in water quality is the fact that its monitoring agencies collect samples directly in front of flowing stormdrains and creeks. Monitoring at these “point zero” locations, where polluted runoff often pools, is the best way to ensure that health risks to swimmers are captured in water quality data, according to Heal the Bay.

Despite Los Angeles’ commendable point-zero policy, many of the most polluted beaches in the county do not sit near storm drains — Avalon Harbor, Cabrillo Beach and several sites in Long Beach, a Heal the Bay spokesman notes.

However, 86 percent of Santa Monica Bay beaches (from Leo Carrillo to Palos Verdes) received A or B grades during the high-traffic summer beachgoing season. While slightly below last year’s grades, these marks show dramatic improvement from annual averages over the past six years, according to Heal the Bay.

Wet weather water quality in L.A. County this past year was the worst since 2004-2005, with 81 percent of the 94 monitored beaches countywide receiving D or F grades following rainy periods.

This growing disparity between improving dry grades and lagging wet grades indicates that cities appear to have made strides to mitigate dry weather pollution but are still grappling with stormwater runoff and the harmful effects it has on year-round ocean users, Gold said. Heal the Bay recommends that no one swim in the ocean during, and for at least three days after, a significant rainstorm.

Statewide, most California beaches had very good water quality this past year during dry weather, with 262 of 307 (or 85 percent) locations receiving very good to excellent (A and B) grades. Overall, only 32 of the beaches (six percent) monitored statewide received D or F grades last summer.

Information, www.healthebay.org/.