Blue-green algae detected in this Muskoka region

Published: October 29, 2019

a-warning-sign-lake-blue-green-algae Photo by djaphoto/Shutterstock

Two words that can incite fear in cottagers are algae bloom. While blue-green algae — microscopic phytoplankton known more formally as cyanobacteria — are found naturally in waterways throughout cottage country, a bloom usually constitutes a toxic amount and poses a danger to humans and animals.

The Simcoe Muskoka District Health Unit (SMDHU) has confirmed that the northern end of Bass Lake in the Muskoka Region is experiencing an algae bloom. Blooms are most common in late summer and early fall, when weeks of warmer temperatures, calm waters, and increased nutrients in the lake form ideal conditions for the bacteria to proliferate.

Jenée Wallace, Safe Water Co-ordinator with the SMDHU cautions cottagers and residents to not drink water from the lake and to ensure that pets are also kept out of the lake, and not allowed to drink from it. Do not use water for food preparation, including in baby formula. Boiling water with visible blue-green algae is not sufficient to eliminate the toxins.

Bass lake is only the latest lake to experience a blue-green algae bloom this season. The Sudbury region confirmed algal blooms on a number of lakes, including Lake Nipissing, and the French River as recently as October 17. Alberta had a number of cases in August and the Ottawa region also confirmed beach closings over the summer. Lake Erie experienced significant blooms this past August.

Not all blue-green algae blooms are toxic, says Jenée Wallace, though it’s best to err on the side of caution. Toxins can occur when the cyanobacterial cell breaks down after a bloom, releasing microcystin, which affects liver function.

Exposure to toxic blue-green algae can also affect our nervous system and skin. Anyone who’s exposed and experiences a sudden onset of vomiting, diarrhea, or headache should seek medical attention as soon as possible.

Even if the bloom doesn’t produce toxins, it can often smell like rot. Algal blooms impact local ecosystems by blocking sunlight and depleting oxygen, which other lake species rely on to survive.

Blooms are frequently the consequence of agricultural and storm sewer run-off, which multiplies the presence of phosphorus in the water, feeding the algae.

We can do our part to reduce the nutrient load on the lake, says Wallace, by using phosphate-free detergents, soaps and cleaning products, avoiding lawn fertilizers, maintaining a natural shoreline along lakes and rivers, and keeping our septic systems in good condition so there is no leakage into waterways.

In the meantime, Bass Lake cottagers (and any others dealing with algal blooms), along with not drinking the water from the lake, should be cautious about eating the fish, and avoid altogether the liver, kidneys or other fish organs.

Wallace also urges the public to report any suspected blooms right away. In Ontario, please call 1-866-MOETIPS.

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