Bay Area beaches received mostly positive reviews in a new report released by an environmental group that rates more than 500 beaches in California for their water quality every year.

Nonprofit organization Heal the Bay rates beaches along the West Coast on a grading scale, which is determined by water quality events, like sewage spills and rainfall, along with routine bacteria pollution sampling. Beaches with a C grade or worse are more likely to have bacteria that can make beachgoers sick with the flu, ear infections and other illnesses.

The cover of Heal the Bay’s 2020-21 Beach Report Card, which can be downloaded from the organization’s website. (Image courtesy of Heal the Bay)

Luckily, 93 percent of California beaches in total scored an A or a B for last summer’s water quality. in the Bay Area, 53 out of the 60 beaches — 88 percent — received an A or B grade.

The region had a greater representation in the report’s “Honor Roll” than in years prior. That is a list of the 35 cleanest beaches across the state with stellar scores in water quality year-round. China Beach and Ocean Beach in San Francisco, along with Robert W. Crown Memorial State Beach at Sunset Road in Alameda, were graded A+.

Many other counties in the Bay Area scored great marks, though they weren’t qualified for Honor Roll without monitoring their wet seasons. All of Marin County’s 24 beaches received A’s, and so did Sonoma’s seven beaches for the county’s third year in a row.

And for East Bay, Alameda and Contra Costa counties had 100 percent of its beaches scoring an A or B throughout the year, numbers that are significantly higher than its five-year average. Heal the Bay said this might be due to East Bay receiving 56 percent less rainfall than usual, which means less pollutant runoff into the ocean and cleaner waters.

Not every beach an award-winner

San Francisco also received great marks for its summer dry season, with 96 percent of the beaches receiving A’s or B’s. Though it had two of the state’s cleanest beaches, Candlestick Point at Windsurfer Circle was the ninth-dirtiest beach in California this year.

Bay Area beaches made up four of the 10 worst-rated beaches in California in the report’s “Beach Bummer” list. Along with Candlestick Point, three San Mateo County beaches, Erckenbrack Park, Gull Park and Marlin Park, were some of the state’s most polluted spots.

San Mateo County beaches have consistently scored low health marks, mostly because their shorelines in Foster City are in the same enclosed space as urban runoff channels, with little circulation to clear out the pollution from the beach. Heal the Bay says it is especially troubling since four of the six beaches that made the list last year weren’t monitored this year, without justification.

“Regrettably, the Foster City area and San Mateo County as a whole have been plagued with poor water quality in recent years,” the report reads. “Last year, six San Mateo County beaches earned spots on the Beach Bummer list. With four of those unmonitored by the county this year, fewer have made the list but the problem of fecal bacteria pollution remains.”

More information about the report and its sampling methods can be found online.