The mountain town of Canmore is in a state of emergency after a normally serene creek swelled to a raging torrent, threatening to wash houses along its banks into the rushing water.

About 40 homes south of the pedestrian bridge over Cougar Creek were evacuated at 2 a.m. MT on Thursday when officials concluded the creek’s banks had become unstable, Canmore Mayor John Borrowman said.

"The situation is actually bad and getting worse," he said. "Now some of the smaller creeks are starting to flood."

The evacuees were taken in at the town’s civic centre and at two local hotels.

Other residents are being alerted to be ready to move if necessary.

John E. Marriott, a photographer who lives along Cougar Creek, said the raging torrent is now four metres from his house.

"The little tiny creek that is behind our house … has gone from being two inches deep and about three metres wide to being 150 metres wide and about five metres deep," he said.

Power is out at various locations throughout the town, officials said.

Both the Trans-Canada Highway and Highway 1A are closed to eastbound and westbound traffic at Cougar Creek.

"We do not advise travel this way," said Canmore RCMP Const. Jeff Jantz. "Don’t come."

Crews are using heavy machinery to try to redirect some of the water surging into the Bow River, he said.

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A house in Canmore in danger of being swept into Cougar Creek. (Courtesy Allan Dwyer)

Another 50 to 60 millimetres of rain is forecast in the area before the skies are expected to clear later on Friday.

Calgary, other towns, in state of emergency

Canmore is about 100 kilometres west of Calgary, where city officials also declared a state of local emergency late Thursday morning "based on the potential severity of the incoming high river flows in conjunction with expected heavy rainfall," the city said in release. 

City officials are implementing flood response plans including deployment of sandbags and temporary dams at key locations.

A STARS air ambulance rescued one of two people they were searching for in the Highwood River.

Crews rescued a man on top of a flatbed truck, but the location of a woman who was seen farther upstream on top of a trailer is not known, STARS officials said.

In High River, about 70 kilometres south of Calgary, officials also declared a state of emergency early Thursday morning after  the Highwood River started overflowing its banks.

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The Elbow River is spilling over its banks in Bragg Creek. (Tara Weber/CBC)

Officials are encouraging residents in the Wallaceville area of town to leave their homes. Campers in George Lane Park have also been told to leave.

The town’s emergency operations centre is open, and crews have been called in to begin sandbagging.

A flood warning has also been issued for Kananaskis Country west and south of Calgary, as the Sheep River threatens to burst its banks in the Okotoks area.

That river also flows through the towns of Turner Valley and Black Diamond, where some residents of low-lying areas are being told to leave their homes.

The Oilfields Arena in Black Diamond is being used as a reception centre.

Sour gas leak contained

A sour gas pipeline ruptured because of the fast rising flood waters, prompting officials to issue an emergency alert for the potential release of hazardous materials.

It has since been contained.

The Alberta Energy Regulator said it is aware of the leak, and that crews were on the way to Turner Valley.

The hamlet of Bragg Creek, 44 kilometres west of Calgary on the edge of Kananaskis Country, is also in a state of emergency as the Elbow River surges over its banks.

Just downstream in the townsite of Redwood Meadows, administration manager Pat Evans said the water is higher than it was during the last big flood in 1995.

Townsite officials are strongly urging residents of Redwood Meadows to leave their homes.

Farther southwest, parts of the Crowsnest Pass are being evacuated because of high water levels.

A log jam in Crowsnest River near the community’s hospital has prompted officials to put the facility on alert. Crews are working to clear the blockage, officials said.

Some residents of Blairmore in the pass, which is about 240 kilometres southwest of Calgary, are being asked to leave their homes.

A reception centre has been set up at the sports complex in the neighbouring community of Coleman.