Likely Algae Bloom Reported Along Central East Bay Shoreline

Jul 31, 2023

SF Baykeeper Suspects Same Red Tide Algae as Last Year

Oakland, CA—San Francisco Baykeeper's field science team investigated reports to the organization's pollution hotline and confirmed reddish brown (“tea colored”) waters in the Berkeley marina, and subsequently along the shores of Emeryville, Berkeley, and Albany. Following preliminary analyses, Baykeeper scientists suspect this is likely caused by an outbreak of the algae Heterosigma akashiwo. Last year, a harmful bloom of the same algae caused a red tide that spread across the Bay, resulting in an unprecedented fish kill event. 

“It’s alarming to see an algae outbreak of this size in the Bay for the second year in a row," said Baykeeper science director Jon Rosenfield, PhD. "While it’s too early to tell how this harmful algae bloom will proceed, there’s not much that we can do to stop it once it has started. Prevention is the only cure."

Algae blooms are fueled by elevated levels of nitrogen and phosphorus, also called “nutrient pollution.” San Francisco Bay has some of the highest levels of nutrient pollution of any estuary in the world. This pollution comes primarily from the region’s 37 wastewater treatment plants, which discharge treated sewage into the Bay. 

“The good news is we know how to reduce the nutrient pollution that fuels harmful algal blooms, and many of these solutions have multiple benefits," Rosenfield added. "We urge the San Francisco Bay Regional Water Quality Control Board to upgrade permits for Bay Area wastewater treatment facilities to dramatically reduce nutrient loads discharged into the Bay, and to encourage nature-based and other multi-benefit solutions." 

Wastewater treatment plants can be modernized to recycle wastewater, which would reduce nitrogen and phosphorus discharges in the process. Building treatment wetlands would capture sewage pollution before it enters the Bay. Restoring the Bay’s historic natural wetlands would absorb excess nitrogen and phosphorus from Bay waters. 

Baykeeper is investigating this algae bloom and its causes in partnership with the San Francisco Estuary Institute, the U.S. Geological Survey, and other agencies and academic organizations. Baykeeper asks anyone who encounters water that looks or smells suspicious to report it to its pollution hotline.

The organism that likely forms this bloom is not known to pose a risk to humans. Regardless, Baykeeper advises caution when entering any water that is discolored.

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