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Cyanobacterial Harmful Algal Blooms (CyanoHABs) in Water Bodies

Certain environmental conditions in water bodies can intensify algae growth, causing algal blooms. Blooms with the potential to harm human health or aquatic ecosystems are referred to as harmful algal blooms or HABs. In freshwater systems, cyanobacteria (previously known as  blue-green algae) are microorganisms that can produce HABs. Some cyanobacterial HABs, or cyanoHABs, can produce toxins. CyanoHABs and their toxins can harm people, animals, aquatic ecosystems, the economy, drinking water supplies, property values, and recreational activities, including swimming and commercial and recreational fishing.


Basic Information about CyanoHABs


Cyanohabs in water
  • Learn about Cyanobacteria and Cyanotoxins
  • Causes of CyanoHABs
  • Exposure to CyanoHABs
  • Health Effects from Cyanotoxins
  • Tracking CyanoHABs StoryMap

Managing Cyanotoxins in Public Drinking Water Systems

Drinking water faucet and glass

  • Cyanotoxins in Public Drinking Water Systems
  • EPA Drinking Water Health Advisories for Cyanotoxins
  • Cyanotoxin Management Tools for Public Water Systems
  • Treatment for Cyanotoxins in Drinking Water
  • Cyanotoxins and the Safe Drinking Water Act: Drinking Water Protection Act, Contaminant Candidate List and the Unregulated Contaminant Monitoring Rule

Managing Cyanotoxins in Recreational Waters

warning sign
  • EPA Tools for Waterbody Managers to Monitor for and Respond to CyanoHABs
  • Recommended Human Health Recreational Ambient Water Quality Criteria or Swimming Advisories for Microcystins and Cylindrospermopsin

Prevention, Control and Treatment

Dr. Heath Mash working in EPA’s Cincinnati laboratory on algal toxins analysis (Cincinnati Stream Facility Sept 2018).
  • Preventative Measures for Cyanobacterial HABs in Surface Water
  • Control Measures for Cyanobacterial HABs in Surface Water
  • Treatment in Drinking Water
  • Cyanotoxins Preparedness and Response Toolkit (CPRT)

Monitoring and Analysis


EPA-ORD Cyanobacteria_microcystis samples from Harsha Lake
  • Determination of Cyanotoxins in Drinking and Ambient Freshwaters
  • Laboratories that Analyze for Cyanobacteria and Cyanotoxins
  • State HABs Monitoring Programs

Research, Collaboration and Other Resources

Jar testing cyanobacterial cell removal case study - EPA Cincinnati Lab

  • EPA HABs Research
  • EPA Newsletter and Collaboration and Outreach on HABs
  • State HABs Resources
  • Other Federal Agencies and Organizations HABs Resources
  • The Harmful Algal Bloom and Hypoxia Research and Control Amendments Act (HABHRCA)
Contact Us to ask a question, provide feedback, or report a problem.
Last updated on April 26, 2022
United States Environmental Protection Agency

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