In an encouraging sign, Los Angeles County showed significant improvement in overall beach water quality in 2009-10, according to Heal the Bay’s 20th annual Beach Report Card released recently.

Heal the Bay assigned A-to- F letter grades to 86 beaches in L.A. County for the dry-weather period from March 2009 through April 2010, based on levels of weekly bacterial pollution. Some 79 percent of sites earned A or B grades, compared to a 70 percent tally in last year’s report and a 73 percent six-year average.

Storm-drain enhancements that treated or diverted polluted urban runoff during prime beach-going season played a major role in the rising grades. Nearly two dozen projects, funded under the state’s Clean Beach Initiative and other local programs, kept potentially illness inducing bacteria from reaching the ocean.

Nonetheless, L.A. County’s water quality remains the worst in the state, scoring well below the statewide average. A handful of chronically polluted beaches in Malibu, Santa Monica, Avalon and Long Beach helped drag down the county’s overall grades.

Seven beaches in the county received year-round F grades, a notable improvement from 2008-09, when 15 beaches earned failing marks. Still, Los Angeles County leads Heal the Bay’s annual Beach Bummer List, with five locations in the ranking of the state’s most polluted beaches.

Avalon Beach in Catalina continues its reign as the most polluted beach in the state, but a much-needed wide-scale sewer replacement project is nowhere on the horizon. Heal the Bay recommends that the county work with Avalon and federal legislators to get American Recovery and Reinvestment Act or state revolving funds to pay for needed repairs and protect public health at the popular tourist destination.

Other county sites on the Beach Bummer List: Cabrillo Beach in San Pedro, Santa Monica Municipal Pier, Colorado Lagoon in Long Beach and Sunset Beach in Pacific Palisades.

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. 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 swimmers at cleaner beaches.

Meanwhile, Orange County beaches recorded outstanding water quality grades, well above the state average. Some 97 percent of 78 locations monitored year-round during dry weather received an A or B during the summer, a modest improvement from last year’s report.

The county’s Poche Beach continues to struggle with poor water quality and joins the Beach Bummer List for the third year in a row. A dry weather filtration plant completed last year has yet to meet performance specifications.

Ventura County also enjoyed excellent water quality in 2009- 10. All of the 19 beaches monitored year-round during dry weather received A grades.

One of the reasons that Los Angeles County lags in water quality is the fact that its monitoring agencies, unlike most others in the state, 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.

Dry-weather water quality in Long Beach improved again for the third year in a row. Some 53 percent of its beaches received A or B grades during the period, which still significantly lags behind L.A. County’s 85 percent A or B total.

Long Beach’s water quality overall is poor because it sits at the terminus of the pollutionchoked L.A. River. The city is to be commended for investigating and fixing leaking or disconnected sewage pump lines and improperly working diversions.

In other good news, water quality in Santa Monica Bay, from Leo Carrillo to Palos Verdes, was excellent during the high-traffic summer beach-going season, with 91 percent of beaches receiving A or B grades. The figure is well above the sixyear summer average.

Thirty-one beaches received F marks during storm season. Cities continue to grapple with stormwater runoff and the harmful effects it has on year-round ocean users. Heal the Bay recommends that no one swim in the ocean during, and for at least three days after, a significant rainstorm.

Looking statewide, most California beaches had very good to excellent water quality this past year during year-round dry weather, with 294 of 326 (90 percent) locations receiving A and B grades. That marks a 5 percent improvement from the previous report. Overall, only 20 of the beaches (6 percent) monitored statewide received D or F grades during year-round dry weather.

The 10 most polluted beaches in California are Avalon Harbor Beach, Cowell Beach, Cabrillo Beach harborside, Poche Beach, Santa Monica Municipal Pier, Colorado Lagoon, Baker Beach at Lobos Creek, Capitola Beach west of the jetty, Vacation Isle North Cove Beach in Mission Bay and Sunset Boulevard and PCH at Santa Ynez Drain.

For more information about the Beach Report Card, go to www.healthebay.org.