Santa Monica Pier: the water quality results are not satisfactory | Photo: Shutterstock

Only 12 of 456 Californian beaches failed the water quality test by Heal the Bay.

The 26th annual Beach Report Card has once again assigned A-to-F letter grades to 456 Californian beaches for three reporting periods in 2015-2016, based on levels of weekly bacterial pollution.

This year's "Top 10 Beach Bummers" includes spots where harmful bacteria may cause major skin rashes, ear infections, and stomach flu. Cowell Beach, in Santa Cruz, is the worst beach for the third consecutive year.

The good news is that 34 beaches scored perfect A+ grades every week of the year, regardless of dry or rainy conditions. With 14 sites, and despite a season with low rainfall totals, San Diego County leads Heal the Bay's "Honor Roll."

"Heal the Bay's policy staff is advocating for public funding measures to build infrastructure projects that capture, cleanse and reuse stormwater rather than dumping it uselessly into the sea," the environmental organization notes.

"While beach water quality grades may be higher in a given year due to less runoff, the results should not provide a false sense of security about long-term improvements at chronically impaired beaches. When the rains come, poorer grades often follow."

The report also reveals that one in four monitored beaches in California received F grades for wet weather and that all of Ventura County beaches earned A grades in the summer.

Heal the Bay's Top 10 Beach Bummers for 2016

Cowell Beach | West of the wharf (Santa Cruz County)
Clam Beach | Near Strawberry Creek (Humboldt County)
Shoreline Beach Park | Shelter Island (San Diego County)
Monarch Beach | North at Salt Creek (Orange County)
Santa Monica Pier (Los Angeles County)
Marina del Rey | Mother's Beach (Los Angeles County)
Redondo Municipal Pier (Los Angeles County)
Candlestick Point/Sunnydale Cove (San Francisco County)
Pillar Point | End of West Point Ave. (San Mateo County)
Pismo Beach Pier | 40 feet south (San Luis Obispo County)