Algal bloom at Grand Lake St. Mary's, Ohio, 2010. Photo by Russ Gibson, Ohio EPA

Cyanobacterial Harmful Algal Blooms

Algae are natural components of marine and fresh water flora performing many roles that are vital for the health of ecosystems. However, when certain conditions are favorable, algae can rapidly multiply causing "blooms." When blooms (or dense surface scums) are formed, the risk of toxin contamination of surface waters increases especially for some species of cyanobacteria algae with the ability to produce toxins and other noxious chemicals. These are known as cyanobacterial harmful algal blooms (cyanoHABs). Cyanobacteria, also known as blue-green algae, are of special concern because of their potential impacts on drinking and recreational waters.

EPA has compiled information on freshwater cyanoHABs including causes, detection, treatment, health and ecological effects, current research activities in the U.S.; and policies and regulations for cyanotoxins at the state and international levels.

Cyanobacteria/Cyanotoxins

The most common cyanotoxins in the U.S.

Detection

Sample collection and list of detection methods available for cyanotoxins.

Health and Ecological Effects

Routes of exposure, adverse human health outcomes, some of the effects on aquatic ecosystems.

Research and News

Current research activities on cyanotoxins in the U.S.

Causes and Prevention

Major causes of HABs and ways to prevent their occurrence.

Control and Treatment

How to mitigate and treat for cyanotoxins in freshwater and drinking water.

Guidelines and Recommendations

Action levels and guidelines from the WHO and the U.S. for recreational and drinking water.

State Resources

State-by-state list of resources and a link to the Inland HABs webpage.

More Information

Links to resources, websites, and activities from EPA, CDC, NOAA, USGS, and international agencies.

For comments, feedback or additional information, please contact Lesley D'Anglada (Danglada.Lesley@epa.gov), Project Manager, at 202-566-1125.