Harmful Blue-green Algae Blooms
- Blue-green Algae and Health brochure is available in Portable Document Format (PDF, 533KB, 2 pp.) View and Order HAB Publications
Blue-green algae are microscopic organisms that can form dense blooms in surface waters. People and animals should avoid blooms because blue-green algae can cause health effects.
Know It
It might be a blue-green algae bloom in surface water if you see:
- Strongly colored water (blue-green, green, yellow, white, brown, purple, or red).
- Paint-like appearance.
- Floating mats or scums.
Avoid It
Always stay away from blooms in surface waters. View DEC's list of reported blooms:
- Don’t swim, fish, boat, or wade in areas with blooms.
- Don’t eat fish caught from areas with blooms.
- Rinse with clean water if you, your family or pets have contact with blooms.
If you are not on a public water supply and are using surface water:
- Bloom or no bloom, never drink, prepare food, or make ice with untreated surface water. You may also consider not using it for washing, especially if it looks cloudy.
- During a bloom, don’t drink, prepare food, or make ice with surface water, even if you treat the water yourself.
- Boiling water will not remove blue-green algae or their toxins. Learn more.
If you are on public water:
- Your water is treated, disinfected and monitored for drinking and household use. Learn more.
Report It
- Report blooms to: the DEC, your local health department, or harmfulalgae@health.ny.gov
- Report blue-green algae related symptoms to: your local health department or harmfulalgae@health.ny.gov
- Consider visiting a healthcare provider if you, your family, or your animals are experiencing symptoms related to blue-green algae blooms. Symptoms include diarrhea, nausea, or vomiting; skin, eye, or throat irritation; and allergic reactions or breathing difficulties.
Learn More
HABs at Beaches
- Special Information for Public Beach Operators
- Harmful Blue-green Algae Bloom Sign Templates:
- Warning Sign: Avoid Blooms While Swimming, Boating and Fishing
- Beach Swim Area Closed Sign: No Swimming or Wading
