Scientists Link Oakland Estuary, Lake Merritt Murky Water to Algal Bloom

Aug 8, 2022

Click here for Baykeeper's latest update about the bloom 


SF Baykeeper Cautions Against Contact with the Brown Waters


OAKLAND—Over the past weeks, many residents and visitors to Lake Merritt, the Oakland Estuary, San Leandro Bay, and surrounding areas of San Francisco Bay have been contacting Baykeeper’s pollution hotline to report discolored water. 


Our staff scientists have been monitoring and documenting the situation and contacting the relevant agencies. After reviewing the results of recent water sampling data from the California Department of Public Health demonstrating the abundance of a common microorganism, Heterosigma akashiwo, our scientists have identified the problem as a large "algal bloom" that appears to be spreading across the Bay.


Also known as red tides, these algal blooms can be toxic to fish, other aquatic life, and to pets. In some instances, they may also cause skin irritation and allergic reactions in people.


Baykeeper executive director Sejal Choksi-Chugh issued the following statement:


"Baykeeper cautions against people or pets contacting the brown murky water, or eating seafood caught in the area, until the algal bloom dissipates. 


“Treated sewage discharges from the Bay's 40 sewage treatment plants and the pollutants from 5 dirty oil refineries create conditions ideal for growing toxic algal blooms. Once a waterway is choked with algal blooms, the water becomes a deadzone for fish and wildlife.


"Baykeeper scientists have been actively working for the past five years through agency technical advisory committees to prevent large blooms of any number of potentially toxic microorganisms from becoming commonplace in the Bay.  We’ve been urging the need to get excessive sewage and refinery discharges under control fast to keep algal blooms like the ones cropping up right now in the Bay from taking over more regularly during summer months. Preventing algal blooms in the Bay is only possible if the San Francisco Bay Regional Water Quality Control Board strengthens its nutrient discharge permit.  And hopefully this is a wake-up call for the agency to take action, because consistent algal blooms in the Bay would be detrimental to wildlife and people recreating in and around the Bay.”

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