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Blue Green Algae
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Cyanobacteria , also known as Cyanophyta, is a phylum of bacteria that obtain their energy through photosynthesis. The name "cyanobacteria" comes from the color of the bacteria. They are often called blue-green algae. When the cyanobacteria cell walls breakdown, they release cyanotoxins, that are harmful to animals and humans. 


CWQA's Position on it:


Take a careful approach to cyanobacteria and algal blooms as some varieties of this algae can produce toxins that are harmful to both humans and animals. If you suspect a blue-green algal bloom:

  • assume toxins are present
  • avoid using, drinking, bathing or swimming in the water (call your local health unit for swimming advisories)
  • restrict pet and livestock access to the water


Contact your local health unit for information on health risks associated with blue-green algal blooms.

If it’s near your surface water supply

Traditional surface water home treatment systems may not be designed to remove toxins and can get easily overwhelmed or clogged, so they should not be relied on. Do not boil the water, or manually treat the water with chlorine or other disinfectants, as this could increase the toxin levels.


If you get your water supply from your own surface water intake in the area of a bloom, you should consider an alternate source of drinking water for the duration of the bloom. Alternative may include using another source of water, or moving your intake well away from the bloom OR upgrading your water treatment system to address the toxins. 


If you are connected to a municipal water supply system or other central water treatment and distribution system, you can continue to use the water normally unless notified otherwise by the system operator or the local health unit. 


If you have your own well supply with a groundwater source (not including shore wells or infiltration galleries), or you receive trucked water in cisterns, you can also continue to use the water normally


How it impacts our members:


Cyanobacteria is an often difficult challenge since it is not a constant source of concern to the drinking water supply but a seasonal one in Canada.   


What is CWQA doing about it:


The US EPA has developed recommendations to municipalities on how to manage and mitigate algal blooms and the risk of cyanotoxins in the water treatment supply. CWQA endorses the recommendations and further support the initiatives taken by the provinces to manage nutrient infiltration into the natural surface water supplies.


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