Nearly three quarters of California counties have some kind of harmful algal bloom, according to the State Water Control Resources Board, prompting warnings at rivers and lakes.  Algal blooms, known as cyanobacteria or blue-green algae, can be found when warm water and abundant nutrients cause harmful algae to grow rapidly and produce toxins in any fresh body of water. They also contribute to nasty odors and taste. … According to the State Water Resources Control Board, 43 of 58 counties have reported harmful blooms. The board website lists the location, extent, and toxicity of the blooms but states that the information may not be accurate due to changing environmental conditions.