Reporting Blue-Green Algae Blooms 

• If you see or suspect a bloom, contact the Ministry of the Environment, Conservation and Parks (MECP) online or by phone.
• The MECP will investigate and test the water for blue-green algae.

Current Waterways Affected by Blue-Green Algae

What is blue-green algae (cyanobacteria)?

• Microscopic organisms naturally found in lakes, rivers, and ponds.
• Thrive in warm, slow-moving water that is rich in nutrients such as nitrogen and phosphorous.
• Normally present in the environment at low levels but can grow into dense blooms when conditions are right.
• Some blooms can produce toxins that can be harmful to humans and animals.

How to spot a bloom:

• Water looks discoloured - green, blue, turquoise, or olive.
• Surface may appear coated with scum, foam, mats, or paint-like streaks.
• Strong odours like rotting garbage, rotten eggs, or decaying plants.
• Dead fish or animals along the shoreline.
• You cannot tell if a bloom is harmful just by appearance. Stay out of the water and keep pets away if you suspect one.

Symptoms and Illness

It's possible to get sick if people:

• Swim, wade, or play in or near contaminated water.
• Drink contaminated water.
• Eat contaminated fish, shellfish, or supplements.

Exposure to contaminated water may cause:

• Stomach pain, headache, vomiting, diarrhea.
• Neurological symptoms such as muscle weakness or dizziness.
• In severe cases, liver damage may occur.
• Skin, eye, nose, throat, or lung irritation.
• Contact your healthcare provider if you develop symptoms after being in water with blue-green algae.
• Swimming, bathing, or showering in areas of the lake without visible blooms is generally safe and not expected to cause health effects.

Protect Dogs and Other Animals

• Animals can get sick or die from drinking contaminated water.
• Watch for symptoms such as vomiting, stumbling, or trouble breathing.
• Wash pets immediately with clean water if exposed.
• Call a veterinarian if symptoms occur.

Drinking Water Systems

Municipal Drinking Water Systems (Town or City water):

• Regularly monitored for blue-green algae blooms.
• Treatment systems remove algae and their toxins.
• Sampling, monitoring, and reporting plans include testing raw and treated water, plus visual checks near intake lines.
• Most municipal systems in Ontario have never had unsafe toxin levels in treated water.
• Residents will be notified if toxins are found above the Ontario Drinking Water Quality Standard.
• Risk of toxins in treated municipal water is very low.

Private Wells and Drinking Water Systems:

If you use a private water supply:

• Check the lake or river often for blue-green algae, especially in summer and fall.
• Treatment systems may not remove toxins, and water may not always taste or smell bad.

If your private water supply may be affected by a bloom:

• Do not drink the water or use it for cooking or baby formula.
• Use bottled water or another safe source.
• Do not boil the water. Boiling does not remove toxins and can increase them.
• Avoid using chemicals like herbicides, copper sulphate, or algaecides which can release more toxins.

What should I do if I spot blue-green algae?

• If you're not sure, stay out!
• Assume toxins are present whenever you see a bloom.
• Stay out of the water and keep pets away.
• Wash with soap and clean water right after exposure.
• Contact your healthcare provider if you develop symptoms after being in water with blue-green algae.
• Report suspect blooms to the Ministry of the Environment, Conservation and Parks (MECP). Incidents can be reported online or by phone.

For more information:

• Blue-Green Algae - Ontario Ministry of the Environment, Conservation and Parks
  Learn how Ontario monitors and responds to blue-green algae blooms.
• Cyanobacteria in Freshwater - National Collaborating Centre for Environmental Health
  Overview of cyanobacteria, health risks, and public health guidance.
• Cyanobacteria Toxins in Drinking Water - Health Canada
  Information on cyanobacteria in drinking water and how they are managed in Canada.
• Guidelines for Canadian Recreational Water Quality: Cyanobacteria and their Toxins - Health Canada
  Details on cyanobacteria in recreational waters and related health concerns.
• Harmful Algae Blooms (HAB): Associated Illness - U.S. Centers for Disease Control and Prevention (CDC)
  U.S. public health information on harmful algal blooms and related illnesses.