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Cyanobacteria and Cyanotoxins in Drinking Water

The State Water Resources Control Board’s (State Water Board) Division of Drinking Water (Division) shares a responsibility to ensure all public water systems throughout California have access to clean, potable water at all times.  The Division achieves this objective by inspecting and evaluating the ability of public water systems to meet state and federal drinking water standards;  providing technical and funding assistance; and, at times, relying on industry, academic and government partnerships to address new technological advances and current public health concerns.

Recently, there has been an increase in reports of harmful algal blooms and potentially associated toxins in California. The State Water Board recognizes that cyanotoxins may present a health concern if present in drinking water. The United States Environmental Protection Agency (USEPA) published non-regulatory drinking water health advisories for two cyanotoxins -- microcystins and cylindrospermopsin. Short-term exposure to these contaminants at or below the advisory levels is not expected to cause adverse health effects. 

Along with health advisories, the USEPA has published recommendations and guidelines for public water systems on developing a cyanotoxin management plan and treatment strategies. The Division believes that USEPA’s health advisories adequately protect public health. The Division recommends that California water systems refer to USEPA’s health advisories and associated materials for guidance in managing cyanotoxins. The Division will collaborate with affected water systems on management plan development, public messaging and related matters.

The Division will continue to engage with public water systems, other agencies and other states to address the emerging health concerns associated with cyanotoxins as they relate to California’s drinking water.

Learn more about cyanobacteria and cyanotoxins from additional links below:

To contact your local Division of Drinking Water office, please refer to the District Map.

Water systems with an emergency should contact the personnel listed in their current Water Quality Emergency Notification Plan.

(Updated 3/30/17)