Harmful algae detected in Lake Merritt water samples
A rusty red color in Lake Merritt that left lake stewards scrambling to sample the water on Mar. 7 has tested positive for the same algae that caused the devastating harmful algal bloom in 2022. On Friday, lake stewards sent water samples to labs run by the California Department of Public Health and San Francisco Bay Regional Water Control Board. Unofficial field testing initially detected no harmful algae. However, lab testing confirmed over the weekend the presence of Heterosigma akashiwo, a type of algae often associated with harmful blooms. Harmful algal blooms, or HABs, occur when certain types of algae grow rapidly and release toxins, lower oxygen levels, and cause other changes in water quality that can kill fish and other marine creatures.