Cyanobacteria, commonly known as “blue-green algae”, are not true algae but are a type of photosynthetic bacteria commonly found in freshwater bodies throughout the
world. When conditions are good, growth increases and cyanobacteria accumulate within the water as a “bloom” or as a blue-green “scum” on the water’s surface. In addition to the nuisance (fouling) and aesthetic (odour) problems caused by blue-green algae blooms, several species of cyanobacteria have the ability to create toxins.
Watch this video from Environment Ontario: What causes blue-green algae blooms?
Toxic blue-green algae – what is it, and what causes it to bloom? We asked our scientists – watch to find out
Reporting and Notification
Water samples can be taken by the Ministry of Environment’s Operations Division staff responding to reports of blue-green algae blooms to confirm the presence of any toxin.
Timiskaming Health will notify the public if there is a risk to public health. The public should avoid swimming, bathing, drinking the water, and allowing pets into the water if the algae bloom is present. If no bloom is present, water can be used for regular recreational activities.
If cyanobacter blooms are reported, the public should:
• Avoid using the lake water for drinking, bathing, swimming or showering and do not allow children, pets or livestock to drink or swim in the lake water.
• Not boil the water because boiling the water may release more toxins into the water.
• Avoid cooking with the water because food may absorb toxins from the water during cooking.
• Exercise caution with respect to eating fish caught in water where blue-green algae blooms occur.
• Not treat the water with a disinfectant like bleach. This may break open algae cells and release toxins into the water.
• Not rely on water jug filtration systems because they do not protect against the toxins
What are the potential health effects from drinking or coming in contact with water containing blue-green algae?
Some blue-green algae produce toxins that can pose a health risk to people and animals when they are exposed to them in large enough quantities. Health effects can occur when surface scum or water containing high levels of blue-green algal toxins are swallowed, through contact with the skin, or when airborne droplets containing toxins are inhaled while swimming, bathing or showering.
Consuming water containing high levels of blue-green algal toxins has been associated with effects on the liver and on the nervous system in laboratory animals, pets, livestock and people. Livestock and pet deaths have occurred when animals consumed very large amounts of accumulated algal scum from along shorelines.
Direct contact, or breathing airborne droplets containing high levels of blue-green algal toxins during swimming or showering, can cause irritation of the skin, eyes, nose and throat and inflammation of the respiratory tract.
Recreational contact, such as swimming, and household contact, such as bathing or showering, with water not visibly affected by a blue-green algae bloom is not expected to cause health effects. However, some individuals can be especially sensitive to even low levels of algal toxins and might experience mild symptoms such as skin, eye or throat irritation or allergic reactions.
Background, potential impacts to human health and safety of drinking water (PDF)Information for drinking water system owners and operator (PDF)