Harmful Algal Blooms
Harmful algal blooms are a major environmental problem in all 50 states. Known as red tides, blue-green algae or cyanobacteria, harmful algal blooms have severe impacts on human health, aquatic ecosystems and the economy.
Algal blooms can be toxic. Keep people and pets away from water that is green, scummy or smells bad.
- Learn about harmful algal blooms
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What are harmful algal blooms?
Harmful algal blooms are overgrowths of algae in water. Some produce dangerous toxins in fresh or marine water but even nontoxic blooms hurt the environment and local economies.
Produce extremely dangerous toxins that can sicken or kill people and animals
Create dead zones in the water
Raise treatment costs for drinking water
Hurt industries that depend on clean water
Did you know?
Climate change might lead to stronger and more frequent algal blooms.
Find out how.
Nutrients (nitrogen and phosphorus)
Nutrient pollution from human activities makes the problem worse, leading to more severe blooms that occur more often.
The following links exit the site Exit
Volunteer to monitor waterbodies for algal blooms
Report suspected algal blooms to your state
State departments of health or environment are the best sources for local information about harmful algal blooms.
Help prevent nutrient pollution
Simple actions around your home and yard can make a big difference
InfographicsClick to see full size.
- October 30, 1pm ET:
New research on cyanotoxins and harmful algal blooms.
Keeping pets- and people- safe from toxic algae.
Two years ago, our family planned to take our Yellow Labrador puppy Fiona to Lake Needwood near our home in Rockville, Maryland for a swim. Read more...
- North American Lake Management Society
- Resource Media
- NOAA Red Tide Forecast
- Woods Hole Oceanographic Institute
- Florida Fish and Wildlife Conservation Commission Red Tide Status
- Florida Mote Marine Laboratory Beach Conditions Report
- Lake Erie Harmful Algal Bloom Bulletin
- Nebraska Department of Environmental Quality Toxic Blue-Green Algae Monitoring
- Ohio EPA Harmful Algal Bloom Advisories
- Oklahoma Department of Environmental Quality
- Oregon Health Authority Algae Bloom Advisories
- Texas Parks and Wildlife Golden Algae Status Reports
- Texas Parks and Wildlife Brown Tide Status Reports
- Vermont Department of Health Blue Green Algae Tracking
- Vermont Watershed Management Division