Alberta Health Services (AHS) has issued a health advisory for a private community lake in Calgary’s southeast.
AHS says cyanobacterial (blue-green algal) bloom toxins have been identified in the waters of Lake Sundance.
Cyanobacteria are naturally occuring and blooms are more common during periods of warm weather.
“They’re getting more frequent, because their summers are getting longer. They’re getting hotter,” explained University of Calgary scientist Marc Strous.
“And there’s nutrients in these lakes, so it’s an ideal situation for these blooms to occur.”
The blooms can take on several colours, including blue-green, greenish-brown, brown, pink or red, according to AHS.
“(Cyanobacterial blooms) can look like scum, streaks, grass clippings, fuzz balls, paint or pea soup. They often smell musty or grassy,” AHS says in its advisory.
The lake, which is exclusively for residents of the Sundance neighbourhood, is still open for recreation — but residents and visitors are asked to take the following precautions:
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- Do not swim or wade in any areas where cyanobacterial blooms are visible.
- Avoid all contact with cyanobacterial blooms in the water and washed up on shore. Wash with clean tap water as soon as possible if contact occurs.
- Do not drink or cook with water from this lake.
- Do not eat whole fish or fish trimmings from this lake as fish may store toxins in their liver. Fish fillets contain fewer toxins and are safer to eat.
- Keep pets away from the water. Do not allow pets to swim in areas where cyanobacterial blooms are visible or to contact blooms in the water or on the shore.
- Do not feed whole fish or fish trimmings from this lake to your pets.
Common symptoms of people who come into contact with cyanobacterial blooms include skin irritation, rash, sore throat, red eyes, swollen lips, fever, nausea and diarrhea.
AHS says those symptoms can appear within one to three hours of contact and usually last for one or two days. Children often experience more pronounced symptoms.
Strous says it’s very hard to use a treatment to get rid of the blooms.
“They will naturally disappear again when the temperatures go down, maybe a longer period of less sunlight, so then all these bacteria that grew in this lake, they will not have sunlight anymore and they will start to die.”
Strous says the gloomy weather over the past couple of days in Calgary should be helpful in mitigating any further growth of the blooms.
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