What Are the Dirtiest Beaches in California?

I’ll start with the good news: 94 percent of California’s beaches logged clean water-quality scores in 2021 between April and October, the months when we’re most likely to take a dip in the ocean.

Heal the Bay, a nonprofit based in Santa Monica, this week released its 32nd annual beach report card, which confirmed that California’s 400-something beaches are safe for swimming year-round — for the most part.

“We are fortunate to have beaches that are beautiful and clean most days of the year,” said Tracy Quinn, the Heal the Bay president, “but unfortunately there are times and conditions when the water at the beach can make us sick.”

Heal the Bay scores beaches based on the levels of bacterial pollution in the water each year between April and October, the prime recreation season in California and the period in which local officials must perform regular water-quality testing. (The ratings consider only samples taken during dry weather, as rain flushes contaminants into the ocean and significantly worsen water quality. This is why you shouldn’t swim in the ocean for at least 72 hours after a storm.)

All California beaches receive a water-quality score between A and F. Swimming in a beach with a grade of C or lower makes it more likely that you will develop infections and skin rashes.

According to the latest analysis in the summer of 2021: Nine percent of Northern California beaches received a grade of C or lower, as did 10 percent of Central California beaches and 5 percent of those in Southern California. You can search for your favorite beach’s 2021 score in the report or check the latest water quality with Heal the Bay’s weekly beach grades.

Luke Ginger, water quality scientist with Heal the Bay, told me that the annual reports were intended to warn the public about dirty water, but also to push policymakers to address issues affecting California’s coast. Some beaches repeatedly rank worst in the state because of structural issues — for example, bacteria easily builds up in coves with little water circulation or run-off is frequently contaminated.

Several disasters also polluted the state’s beaches last year, including an oil spill off the coast of Huntington Beach and a wastewater treatment plant that spewed 17 million gallons of raw sewage into the waters off Los Angeles County. “All of these spills had to do with failure of infrastructure,” Ginger told me.

So, how worried should you be when planning your next beach day? Where should you maybe think twice before heading into the water?

Here are the dirtiest beaches in California:

1. Erckenbrack Park (San Mateo County)

2. Marlin Park (San Mateo County)

3. Santa Monica Pier (Los Angeles County)

4. Mother’s Beach (Los Angeles County)

5. Moonstone County Park (Humboldt County)

6. Newport Bay, Vaughn’s Launch (Orange County)

7. Lakeshore Park (San Mateo County)

8. Tijuana Slough, north of the Tijuana River mouth (San Diego County)

For more:

Pistachio-lemon bars.

Where we’re traveling

Today’s tip comes from Jim Welte, who recommends a popular Marin County destination:

“Sitting just 12 miles north of the Golden Gate Bridge, Mill Valley manages to straddle its rich history and its vibrant present with allure. At the heart of it all is the Depot Plaza, the former hub of the Mt. Tamalpais and Muir Woods Railway, which brought passengers from the Depot to surrounding natural park areas. Thomas Edison himself filmed the railway in 1898. Long home to rock stars and tech icons, Mill Valley sits at the base of Mount Tamalpais, whose trail network serves up stunning natural beauty. The town also has a cultural history in the arts, with creative hubs delivering enriching arts and entertainment. It also punches well above its culinary weight!”

Tell us about your favorite places to visit in California. Email your suggestions to CAtoday@nytimes.com. We’ll be sharing more in upcoming editions of the newsletter.

Tell us

Summer is here. What’s your favorite part of the season in California?

Email us at CAtoday@nytimes.com with your stories, memories or recommendations.

And before you go, some good news

The world’s largest animals have been spotted off the Southern California coast in recent days.

Since Friday, whale watchers have spotted blue whales, often with their calves alongside them, in the waters near Catalina Island and Laguna Beach. The massive creatures can reach up to 100 feet long, The Orange County Register reports.

“When you think that the blue whale is the largest animal to live on the planet — bigger than a dinosaur or a megalodon — that is amazing,” said Nona Reimer, a naturalist for Dana Wharf Sportfishing and Whale Watching.

Thanks for reading. I’ll be back tomorrow. — Soumya

P.S. Here’s today’s Mini Crossword, and a clue: Sea creature that sings (5 letters).