Heavy rains in southern Alberta have caused flooding, mudslides and the closure of the Trans-Canada Highway through the national park resort town of Banff.
Several communities in the mountains and foothills have declared states of emergency and ordered evacuations as rivers swell and rising water threatens roads and bridges.
The town of Canmore just outside the gates of Banff National Park is warning residents in one neighbourhood that they will be cut off if they choose to stay.
Town spokeswoman Sally Caudill says Canmore itself is also isolated because of the closure of the Trans-Canada both east and west of the town.
The RCMP were warning of several mudslides on roads around Banff and in the popular recreation area of Kananaskis. Several sections of highway were reported to be washed out.
Caudill says motorists were trapped by water spilling over the Trans-Canada and had to be rescued by choppers overnight.
"We had about 20 or so people on the highway ... who got stuck ... (when) water covered the highway in two places, so we used a helicopter to get those folks out."
Caudill says a creek that runs through her community is rising quickly. The town's website says the creek's banks are unstable and dangerous.
"Cougar Creek is very serious and changing very quickly," Caudill said Thursday morning. "Homes that back immediately onto the creek have been evacuated starting at about 3 this morning. We are now extending that evacuation to homes within about a 45-degree radius."
Similar threats were being felt in High River, Black Diamond and Turner Valley — communities along what is know as the Cowboy Trail in the foothills of the Rocky Mountains.
A mandatory evacuation was issued for neighbourhoods in High River and in Turner Valley, while residents in Black Diamond were warned to be ready to leave their homes.
Heavy rainfall and lightning overnight Wednesday also resulted in power outages and flashing traffic signals in every area of the city of Calgary. Crews were out Thursday trying to repair the damage.
Environment Canada has issued a rainfall warning for the area, estimating as much as 100 millimetres of more rain could fall in the next two days.