Northern California is home to some of the most breathtaking beaches in the Golden State, but not all of them are exactly the healthiest.
According to a nonprofit group's annual report released Thursday, seven of the 10 most polluted beaches in California are located in the northern half of the state with five of those seven situated in the greater Bay Area.
Nonprofit group Heal the Bay ranked the most polluted beaches across the state by examining the levels of harmful bacteria found in the water.
Lakeshore Park at Marina Lagoon in San Mateo County was dubbed as the most polluted beach in Northern California and second-most polluted beach in the entire state, according to the report. Linda Mar Beach — also in San Mateo County but on the west side of the peninsula — checked in right behind as the second-most polluted beach in Northern California and third-most polluted beach in California.
Roosevelt Beach in San Mateo County (No. 5), Cowell Beach in Santa Cruz County (No. 8) and Surfer's Beach in San Mateo County (No. 10) were the other three Bay Area beaches to appear on most polluted beaches in Northern California list, according to the report.
According to Heal the Bay, about 88 percent of the 96 beaches across Northern California that were tested earned A or B water quality grades for the summer season this past year, but that number represented a 3 percent drop compared to the summer season average recorded over the past five years. During the winter season, only 68 percent of Northern California beaches were healthy enough to receive A or B grades. That's a 16 percent drop compared to the five-year winter season average.
On a positive note, not all is bad with the water along California's coastline. Of the 15 beaches examined in San Francisco County, every single one received an A or B grade during the summer, according to the report. Seven out of the eight beaches analyzed in both Alameda and Contra Costa counties also earned A's or B's during the summer months.
Beaches in Sonoma County "boasted stellar water quality," according to the report. Seven beaches in the county scored A grades in both summer and winter. Marin County beaches also checked in on the healthy side. All of the 23 beaches tested grabbed A or B grades.
South in Santa Cruz County, 13 beaches in the area grabbed grades that were considered to be "well above average," according to the report. In a county continuously packed with beachgoers, 92 percent of beaches received A or B grades during the summer while 88 percent scored A's or B's during the winter.
Heal the Bay put together its 2017-18 beach report utilizing bacterial pollution data measured by various counties up and down the coast. The nonprofit's Northern California report included beaches located in Alameda, Contra Costa, Del Norte, Humboldt, Marin, Mendocino, San Francisco, San Mateo, Santa Cruz and Sonoma counties.