Blue Green Algae Bloom

Preparing for Algae Blooms – What You Should Know

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Blue-green algae bloom

Blue-green algae (cyanobacteria) are a type of algae that can produce toxins that can be harmful to people, pets and livestock. Algae blooms, or the overgrowth of algae, can occur in lakes and other surface waters. Warm and calm weather combined with high levels of nutrients (phosphorus and nitrogen) during the summer months can create ideal conditions for algae bloom development.

Algae blooms will form floating clumps or scums, sometimes making the water look like thick pea soup or paint, and may emit a strong, unpleasant odour. However, not all algae blooms produce toxins, and there is no visual way to detect if toxins are present in the water.

Home and cottage owners who use lake water as a source of drinking water should be aware that most small residential treatment systems are unable to remove algae toxins. Boiling or adding chlorine to the water will not remove the algae toxins.

What are the Symptoms of Algae Toxin Exposure?

Symptoms of algae toxin exposure may include: nausea, vomiting, headache, diarrhea, skin/eye irritation, fever, muscle and joint pain, respiratory symptoms, allergic reactions and occasionally other more severe health effects. Algae toxin exposure has resulted in animal deaths in Manitoba.

If you experience symptoms that may be related to algae toxins, please see your health care provider. Contact Health Links – Info Santé at 204-788-8200 (toll free at 1-888-315-9257) if you are concerned about health effects.

What You Can Do

If you have an infant: As a precaution, avoid using water from small private surface water systems to prepare infant formula during the summer months. Infant formula should be prepared using a safe alternate drinking water source (such as bottled water).

Watch your lake for algae blooms. If you observe an algae bloom, take the following precautionary measures:

  • Avoid drinking, swimming or bathing in water with algae blooms.
  • If an algae bloom is observed on the lake that supplies your small water system, use an alternate water source (such as bottled water) for drinking, food preparation, bathing, other personal hygiene and pets.
  • If you are visiting a beach, avoid swimming or bathing in water if you see an algae bloom. Manitoba routinely monitors public beaches for algae blooms and posts beach advisories when concentrations pose a health risk.
  • Keep pets and livestock out of the water if you see an algae bloom.
  • Algae toxins can accumulate in fish, particularly in the internal organs, like the liver and kidneys. Avoid consuming the internal organs of fish and avoid consuming fish that appear unhealthy in waters experiencing algae blooms.
  • Notify your neighbours and report the algae bloom at or 204-945-0002.

For More Information

For more information on beach conditions and algae blooms, please contact the Water Science and Watershed Management Branch at 204-945-0002 or visit the website at

For more information on algae toxins in drinking water, please contact the Office of Drinking Water at 204-945-5762 or visit the website at

For information on your municipal drinking water system, contact your water supplier.