What resources and guidance are available to address harmful algal blooms?

Help is out there for local health agencies, lake managers, park rangers, and the public.

Cyanotoxin Guidance for Recreational and Related Water Uses

When a cyanoHAB is occurring, it is critical that there is understanding of the cyanobacteria and cyanotoxins present and communication of the risk to protect public health. Currently, there are no federal or state standards for cyanotoxins in drinking water and recreational waters. Participating agencies - State Water Board, OEHHA, and CDPH - have developed and are further refining suggested guidelines for addressing health concerns for cyanotoxins in recreation waters. The Department of Public Health, county health departments, and water body managers are encouraged to use this guidance for posting of water bodies when cyanoHABs pose a health threat.

Drinking Water

Releases of cyanotoxins by harmful algal blooms create concerns for drinking water sources, treatment of drinking water, and the safety of drinking water.

  • The State Water Resources Control Board’s Division of Drinking Water is developing a communication strategy and resources for drinking water treatment plants to ensure the provision of safe drinking water.
  • The U.S. Environmental Protection Agency posted Health Advisories in May 2015 to provide guidance for drinking water on the cyanotoxins microcystin and cylindrospermopsin.
    • Health Advisories and health effects support documents
      Non-regulatory concentrations of the two algal toxins in drinking water at or below which adverse human health effects are not anticipated to occur over a ten-day exposure period.
    • Support document for managing cyanotoxins in drinking water
      Provides information and a framework that public water systems (PWSs) and others can consider using to inform their decisions on managing the risks from cyanotoxins to drinking water. Includes a potential stepwise approach PWSs could use to inform their decisions on whether and how to monitor, treat, and communicate with stakeholders.

Shellfish Harvesting and Biotoxins

California Department of Public Health


Monitoring of cyanoHAB is critical to understanding the dynamics of a bloom, deciding on best management strategies, and protecting aquatic life and public health. There are many challenges to monitoring due to available resources, size and dynamics of the water body, and laboratory analytical techniques. The State Water Board's Surface Water Quality Monitoring Ambient Monitoring Program (SWAMP) is focused on developing a statewide monitoring strategy for cyanotoxins, guidance for field and laboratory protocols, and a satellite monitoring program to be a first alert system for cyanoHABs in larger water bodies.  For more information on current monitoring projects, please contact CyanoHAB.Reports@waterboards.ca.gov.

Laboratory Resources

It is important to detect the presence of cyanobacteria and cyanotoxins in drinking and recreational water, as well as detecting bioaccumulation in freshwater and marine organism tissues. Having rapid and accurate detection methods - including visual and qualitative methods along with quantitative laboratory techniques - are critical to ensure the proper management of cyanoHABs. The State Water Board's Office of Information Management & Analysis is focused on bringing together laboratories to develop cyanoHAB data comparability and improve cyanoHAB data interpretation. Laboratories that are interested in joining the Cyano Lab Network, please contact marisa.vandyke@waterboards.ca.gov.

Freshwater Assessment and Support Strategy

The Surface Water Ambient Monitoring Program has released a Statewide Freshwater Harmful Algal Bloom Assessment and Support Strategy that outlines actions and infrastructure being developed to support local response to HAB events.

Freshwater Incident Response and Interagency Coordination

These documents were developed in July 2016 by an interagency team representing California State government organizations charged with responsibilities to address harmful algal blooms (HABs) through either notification or management tasks and activities. The team broke into two groups, one focused on incident response and interagency coordination and communication and the other focused on how to coordinate and best communicate this critical information to the public. These documents are "working drafts" and may be updated regularly to be made more useful to the teams and stakeholders using them. If you have any comments on these documents or questions about their use please contact Greg Gearheart at greg.gearheart@waterboards.ca.gov or (916) 341-5892.

Control and Treatment of Blooms

Measures to prevent, mitigate, remediate blooms in surface waters and drinking water supplies

Related Programs and Organizations