Blue Green Algae Health Advisories

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After four years and almost 100 blue-green algae advisories for Alberta lakes, the provincial health authority is changing the way it warns the public about the scummy, green growth that occurs in some of the province’s favourite swimming spots every year.

Lake users will be told if the toxin-producing organism is present — but they will only be cautioned to stay out of the water if a blue-green algae bloom is visible, often appearing as scum, fuzz or globs on the surface of water.

It’s a significant change from when Albertans were cautioned not to swim or wade in a lake where blue-green algae had been detected, no matter the size of the lake or the size of the bloom. The warning system had been in place since 2011 after the formation of Alberta Health Services, and advisories were widely disseminated through news outlets and social media.

“When people were getting these health advisories, they were getting the mental image that an entire lake was totally covered with algae and deadly to swim in,” said Mayor Don Davidson of the summer village Grandview on Pigeon Lake.

Davidson blames the media for misinterpreting the advisories, sometimes using photographs from an extreme blue-green algae bloom that plagued Pigeon Lake in 2006.

“People would be going to the lake and they’d hear on the radio that there are blooms at various lakes and they’d turn around to go home.”

Blue-green algae is actually a bacteria called cyanobacteria, which is present in all Alberta lakes. But the bacteria thrives with heat, light and nutrients such as phosphorous and nitrogen. Alberta’s nutrient-rich soils mean its lakes are prone to blue-green algae especially in hot summer months, while development and agriculture activities also introduce nutrients into a lake.

The blooms, and the toxins they produce, can make people or animals sick. Humans can experience skin irritation, rashes, sore throats, red eyes or swollen lips, among other symptoms. Drinking the water can lead to more serious illness, especially in pets or livestock that may drink a lot of lake water.

“It is AHS’s duty to protect health and to ensure the public is aware of potential risks to their health. This is why AHS issues blue-green algae advisories,” Dr. Gerry Predy, senior medical officer of health with AHS, said in an email.

“Historically, we have placed less emphasis on the visibility of blooms as the measure of concern. This new messaging will better convey the importance of avoiding visible blooms, rather than whole lake avoidance ... Blooms can move rapidly from one location in a lake to another, and it is not possible for us to know where in a lake these may be, which is why we have further emphasized the importance of avoiding visible blooms.”

Many who live in lakeside communities or work closely with them say there’s no doubt the four-year-old advisory program was causing a degree of “panic.”

Alberta lakes may be experiencing more blooms because of increased development in local watersheds, but there has also been an increase in monitoring and how the public is informed.

“One of the problems was that people were saying, ‘We never had blooms before,’ ” said Bradley Peter, Lakewatch program manager with the Alberta Lake Management Society (ALMS).

“I think there was a misunderstanding with the advisory program and it took a lot of work to educate people that they weren’t monitoring it before; you’ve probably always had this and you just weren’t warned about the toxicity.”

The society does extensive data collection in Alberta lakes and Peter said the society was previously taking “the most cautious” route with its advisories, but that the position changed as more data was collected.

“From ALMS’s perspective, we’re really glad because the changes they’re making to the advisory system is based on the evidence they’ve collected with all of these samples over the years,” he said.

Arin MacFarlayne Dyer, the society’s executive director, hopes people won’t be unnecessarily avoiding Alberta lakes.

“With somewhere like Pigeon Lake, there’s sometimes the feeling that nothing can be done. But that should change with the message that you can swim in it, as long as you don’t see a green patch. And hopefully people understand that some green patches are completely natural.”