There are many types of algae in the water. They are part of the regular ecology of lakes, rivers and wetlands.
However, some types of algae, which are lumped into a group called the blue-green algae, are known to produce toxic chemicals when the cells break down or die. If ingested over extended periods of time, health concerns may include liver damage or damage to the nervous system. Bathing can also cause irritation of the skin or eyes.
Symptoms from ingesting these toxins can include headaches, fever, diarrhoea, abdominal pain, nausea and vomiting. The skin irritation can also include symptoms much like hay fever. It is not often fatal, but it can be more serious with young children.
The blue-green algae become a problem when they concentrate in large “blooms”. Normally the algae use light to activate mechanisms that keep it suspended at certain depths in the water. Without light, at night, the algae become buoyant and float to the surface. This is why people sometimes notice large areas of floating scum that seem to have appeared overnight.
Some of the toxic byproducts of these algae are very stable, and can remain in the water for long periods of time. It is also very difficult to filter them out of the water supply. Few home water treatment systems are able to rid the water of these toxins. For information about removal of blue-green algae and its byproducts, refer to a water treatment specialists.
As a result, the Health Unit warns that any time a blue-green algae bloom appears, people should stay away from it. It should not be used for drinking, washing dishes, bathing or laundry. People should not swim or paddle in the area. Pets need to be kept away from the water source as well, since the toxins have been known to kill domestic animals.
A more detailed question and answer sheet on blue-green algae is published by Health Canada, titled “Blue-Green Algae (Cyanobacteria) and their Toxins.”
Click here to download a PDF file of the Health Canada document.
For more information or advice, call a public health inspector at the health unit office nearest you.
North Bay – 705-474-1400
Parry Sound - 705-746-5801
Burk’s Falls - 1-800-563-2808
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