Police and fire teams are searching for the body of a man believed to have drowned in Chestermere Lake on Monday.
Two men were swimming with a paddleboard near Anniversary Beach at 3 p.m. when they fell into the water, police say.
They immediately began to struggle, and police said nearby swimmers were able to rescue one man but not the other. He sank under the water and hasn't been seen since.
Local fire rescue and RCMP boats were dispatched and were searching the area on Monday evening. The rescued swimmer was taken to hospital by EMS as a precaution.
Cpl. Troy Savinkoff said the search is being considered a recovery.
"Primarily our efforts are looking under the water at this point," he said.
Police say officers met with the missing man's family, and his identity is not being released at this time.
The lake is an irrigation reservoir built in the 1880s that is now surrounded by the City of Chestermere, which borders the eastside of Calgary. The lake covers 2.65 square kilometres and is up to seven metres deep.