Local Beaches Get Mixed Water Quality Results

Jen Kalt, Humboldt Baykeeper Director

For the first time in many years, not one Humboldt County beach appears on the annual Beach Bummer List! Although Clam Beach once again received an F for summer water quality, it didn’t make this year’s top 10 most polluted beaches in the state. That’s because most of California received a ton of rain this year – overall, 50 percent more in coastal counties than the 10-year average. 

Every summer, Heal the Bay publishes the Beach Report Card, which evaluates bacteria pollution at beaches where people swim, surf, and play in coastal waters. These beaches are monitored for fecal indicator bacteria, since exposure can cause nausea, diarrhea, and other illnesses, particularly in young children. 

This year’s exceptionally rainy winter and spring resulted in a statewide decline in Wet Weather Grades, making North Coast beach water quality better in comparison to typically drier regions to the south.

Rain impacts water quality in two ways. It flushes non-point source pollution into coastal waters, including fecal bacteria. It also can cause sewage spills by seeping into poorly-maintained sewer lines, overwhelming sewer pump stations and treatment plants. 

The good news is that in 2021, a rigorous study of Clam Beach and Strawberry Creek found that most fecal pollution in the surf zone is from birds. Just a short distance away, the beach at the Mad River Mouth got an A+ grade – that’s most likely because the Mad River has much higher flows that push polluted water further offshore than small streams like Strawberry Creek and Little River. This hypothesis is supported by a recent study using pink dye that found that where a small stream in Southern California meets the sea, the dye stayed in the surf zone rather than moving offshore.

While additional studies are needed to identify the sources of bacteria pollution at Moonstone, Trinidad, and other local beaches, studies of coastal watersheds in our region point to cattle as the primary source in freshwater. 

This is particularly problematic for commercial oyster farmers in North Humboldt Bay, which are required to stop harvesting after major rainstorms. This winter, some oyster farms were closed for three months straight. 

While this type of pollution has been the subject of numerous studies over several decades, more studies are currently underway. The  Regional Water Board is monitoring Jolly Giant Creek in Arcata, which had more human bacteria than any other coastal stream included in a 2016-18 study across Mendocino, Humboldt, and Del Norte Counties. The source is likely municipal sewer lines, and although the City has upgraded many of them recently, the pollution appears to be ongoing.

Humboldt Baykeeper is in the midst of sampling Janes Creek in Arcata and Mad River Slough for bacteria from human, ruminant, dog, and bird sources, thanks to a grant from the Rose Foundation for the Environment and Communities. We’ll keep you posted on the results when our study wraps up later this year.

Humboldt Beach Grades

The Humboldt County Department of Environmental Health monitors five beaches from April to October. Overall, Summer Dry Grades were very poor this year with only 40 percent of the beaches receiving A and B grades, which is below average. Wet Weather Grades were also poor but better than average, with 60 percent of the beaches receiving A and B grades. Testing is not done from November to March. For the most recent test results, visit humboldtgov.org/1696/Water-Quality-Test-Results.

Regardless of the sources, you can avoid exposure to bacteria pollution by avoiding contact with water for three days after major rainstorms. That’s because the bacteria can’t survive long outside the guts of warm-blooded animals. Another good general rule is to swim, surf, and play in the ocean away from creek mouths and stormwater discharge pipes.

Stay Connected

  • humboldtbaykeeper.org
  • alerts@humboldtbaykeeper.org
  • IG @humboldt_baykeeper
  • TW @HumBaykeeper
  • FB /HumBaykeeper