Heavy winter rains have taken a toll on the water quality of the hundreds of beaches across California, according to a recent report from the nonprofit organization Heal the Bay.

The major concern: The level of poop in the water.

“An alarming 45 million gallons of sewage were spilled into the ocean and coastal waterways, in part due to the increased rainfall. Sewage lines are commonly flooded with rainwater causing them to overflow,” the report, released this week, said.

Storm drains often overflowed during the rains, releasing contamination and sewage into creeks or rivers that empty out to these beaches.

San Mateo County, in particular, has many of these — and five of the state’s ten dirtiest beaches are listed among the report's worst offenders, on the "Beach Bummers" part of the list, according to KNTV. That includes popular spots like Redwood City’s Marlin Park, Foster City’s Gull Park and Erckenbrack Park, and Half Moon Bay’s Pillar Point.

Even the home of the prettiest Taco Bell in the world, Pacifica's Linda Mar Beach, made the list. KTVU dubbed it “Poo-cifica” because of its high levels of the bacteria enterococcus.

Heal the Bay determines these A-plus to F grades by evaluating the water quality, based on water samples tested for bacteria and pollution, including fecal matter. It assigns those grades to 500 beaches from Tijuana, Mexico, all the way up to the Canadian border, according to the SF Examiner. A higher grade indicates a lower risk of individuals contracting illnesses while using the ocean.

The report differentiated grades for the recent wet months and summer dry months — when water is at lower risk of exposure to pollutants. All 16 beaches in San Francisco received high marks for water quality, during these dry months. But nine of these received a C, D, or F during wet months.

The report attributes these poor grades to one spill over the winter that apparently sent 2.3 million gallons of sewage into the Bay near Crissy Field and Aquatic Park, closing both for many days. Luckily, SF has a combined sewer system, which means that rain runoff flows into that and gets treated instead of flowing into the ocean.

Bean Hollow State Beach in San Mateo County was one of only two California beaches to receive an A-plus rating for water quality in both dry and wet conditions throughout the year, earning a spot on the cleanliness "Honor Roll."

Beaches north of the Golden Gate also got generally good ratings — only 25% of Alameda County's beaches for C, D, or F grades during the wet weather, and only 4% of Marin County's did. Still, Marin County just announced that the central section of Stinson Beach has high levels of enterococcus bacteria and shouldn’t be used for water recreation, per the Chronicle.

Feature Image via Wikimedia Commons/Bob n' Renee.