Three lakes near Calgary have been placed under blue-green algae advisories.
Officials issued an advisory for Eagle Lake, located 60 kilometres east of Calgary, on Thursday.
An advisory for Cochrane Lake, located just north of Cochrane, was issued Friday.
There was also an advisory issued for Severn Lake, located northeast of Calgary.
The algae produces a toxin that can cause skin irritations or make people sick if they swim or wade in it, officials said.
It's also dangerous for pets and livestock.
Alberta Health Service's medical officer of health, Dr. Brent Friesen, said people should stay out of the lake.
Don't drink the water, say officials
"It's also important for people to realize that boiling water from a lake with blue-green algae advisory on it doesn't inactivate the toxin. So, again, they shouldn't be using that water for drinking purposes," he said.
The algae will probably remain in the water until temperatures get colder this fall, Friesen said.
Leslie Pringle, owner of the Eagle Lake RV Resort, said the shallow lake has had blue-green algae before.
"We find that when people know ahead of time they're more accepting of it. And people are coming back to a place where they understand that nature is part of our lives," she said.
The notice went up Wednesday, so Jennie Brade and her family said they weren't aware of the warning.
"I might have to tell the kids a few times not to go in the water and they might be disappointed at first," she said.
"But there's so much to do here. They have the petting zoo, they have the play room, they have mini golf, paddle boats."