Late last week, our community science monitoring program detected a harmful algae bloom (HAB) of Heterosigma akashiwo at Seaplane Lagoon and Encinal Beach in Alameda.

H. akashiwo is the same species of algae that produced widespread blooms in 2022 and 2023, causing massive fish die-offs.

We have one unconfirmed report of a localized bloom on the San Francisco shoreline. However, at this time, the HAB appears to be mostly confined to the Bay side of Alameda Island. 

Baykeeper’s field team will continue to monitor the situation and coordinate closely with local agencies.

We strongly recommend that people and pets avoid contact with any discolored water in the Bay.

If you see signs of a bloom—including reddish, murky water—please contact our pollution hotline.

Pictured: A volunteer uses a net to take a sample of discolored water as part of Baykeeper’s community science monitoring for harmful algae blooms.