Cyanotoxins are produced by bacteria called cyanobacteria. They are an essential part of the environment that have existed for millions of year and produce oxygen. Under certain conditions, they multiply excessively and form visible clumps in the water, surface scums, mats, or an oily sheen on natural water bodies. On occasion, they produce toxins that can cause harmful effects in people, pets and livestock if exposed through ingestion, inhalation of aerosolized water or direct contact. Visible and potentially toxic overgrowths of cyanobacteria are referred to as “Harmful Algal Blooms” or “HABs.” Freshwater HABS may occur in rivers, lakes, streams and ponds. The current HAB in Copsey Creek is an unusual occurrence in Lake County, but may be related to physical conditions that cause localized slowing down of the flow of water.
As environmental factors change, most HABS resolve over time. However, when cyanotoxins are known to be present, re-testing the water after it has cleared and allowing at least two weeks to pass after no toxins are found is recommended.
For more information, please visit:
California Harmful Algal Blooms Portal:
California Cyanobacteria and Harmful Algal Bloom (CCHAB) Network:
California Surface Water Ambient Monitoring Program Freshwater HAB webpage:
California Department of Public Health:
U.S. Environmental Protection Agency: CyanoHAB website