Environment Haliburton! (EH) attracted hundreds of people Feb. 9 for a discussion on blue-green algae blooms.

Dr. Elizabeth Favot, an assistant lake stewardship coordinator with the Federation of Ontario Cottagers’ Associations, spoke to blooms and her research into how they form. The discussion also featured additional commentary from ecosystem management professor, Barb Elliot, and environmental scientist Dr. Norman Yan. Approximately 300 people registered for the session.

Favot said blooms can be caused by several factors, including nutrient runoff such as phosphorus reaching lakes, shifting lake levels and climate change. She said more research is needed to account for some lakes experiencing blooms without many changes in nutrient levels.

“Nutrients are of course critically important to support blooms, but in terms of the drivers or triggers, they are not always the entire story,” Favot said.

The presentation comes after the Ministry of Environment, Conservation and Parks confirmed blue-green algae blooms in six Haliburton lakes last fall, though none showed toxin levels above the drinking water standard. However, Favot said a precautious approach is normally used to assume they are producing toxins given some uncertainty around what conditions lead to toxins.


The presentation highlighted every aspect of blue-green algae, more technically known as cyanobacteria. Favot discussed how blooms are becoming increasingly common in Ontario and how they can create toxins that are potentially deadly if consumed. Favot said although nutrient runoff is a significant factor, there are other reasons for the increase, such as climate change causing temperature and conditional changes in lakes which can help blue-green algae thrive. Her doctorate examined the causes of blooms in the approximately 26 per cent of lakes globally with a low phosphorus concentration.

“Even if nutrients have not increased, blooms can still occur in a modern climate,” Favot said. “Climate change is lowering critical nutrient thresholds for blue-green algae blooms to occur.”

But Favot said from a management perspective, people should utilize terrestrial plants to filter nutrient runoff.

“What we can do to mitigate them is relatively straightforward,” Favot said. “We need to keep nutrient concentrations in lakes as natural as possible.”

Elliott agreed. Speaking to a question about the importance of natural shorelines, Elliott compared them to a Jenga game, and how taking away natural parts from shorelines repeatedly can make them unstable.

“I liken it to death by a thousand cuts,” Elliott said. “When we make those changes, it just creates the potential for there to be more impacts because of that activity. We have to try to keep it as natural as we can.”

Although about 300 people registered, only 100 people watched live due to technical issues with Zoom, the online platform used.

“It is a shame there was a wrinkle in our Zoom plans,” EH! President Susan Hay said. “I’m sorry for those who joined late because you couldn’t get in earlier.”

The full presentation is available on the EH Youtube channel.

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