Alberta Premier Alison Redford warned that tough times are ahead as communities south of Calgary brace for raging floodwaters, but said they're ready to meet the challenge.

The focus of emergency alerts in the province has shifted to the southeast, towards Lethbridge and Medicine Hat, which are both under flood warnings.

Redford spoke to reporters Saturday in Medicine Hat, where she praised an "incredibly integrated team of first responders" working to prepare the city.

"This will be a very challenging time for Medicine Hat," she said. "There will be a lot of uncertainty and people will be afraid. I want people to know we have the opportunity to get through this.

"There is no doubt that this is a community that is prepared," she added.

At least 175,000 people in Alberta have now been ordered to evacuate their homes following massive flooding throughout the province.

Colin Lloyd, managing director of the Alberta Emergency Management Agency, said that about 75,000 people have already been told to seek shelter at higher ground in Calgary. Another 100,000 Albertans outside that city have also been placed under mandatory evacuation.

The South Saskatchewn River is expected to crest Monday and city officials are projecting flow levels as high as 6,000 cubic metres per second in the early morning.

Evacuation notices went out to 10,000 homes along lower-lying areas of Medicine Hat last night, while city crews worked to shore up locations such as the city's power plant and water treatment facility. Dozens of volunteers turned out to help — so many in fact that there weren't enough sandbags to go around.

Many of the volunteers said they felt compelled to help after seeing the devastating images of the flooding in Calgary.

Medicine Hat mayor warns citizens to flee

Medicine Hat has now evacuated over 3,700 homes and authorities told CBC's Briar Stewart that they plan to shut off power and gas from those houses as a safety precaution.

But the evacuation order doesn't necessarily mean everyone will abide by the rules and allow themselves to be displaced for their own safety — a potential concern for the community, said Medicine Hat Mayor Norm Boucher.

The locals are well aware of the magnitude of the destruction upstream in Calgary, and as they packed up to leave for higher ground, Stewart said there's a great deal of uncertainty about what they'll be returning home to once the threat subsides.

He said residents are "generally complying" with evacuation orders, but said about 20 homeowners refused to leave the evacuation zone until reassured by police that their homes would be protected.

Many residents were being moved to Medicine Hat College. Inmates from the the Medicine Hat Remand Centre have been transferred to facilities in Lethbridge or Calgary. 

Redford pleaded with residents to comply with evacuation orders.

"I know when we look at the sky and the sun is shining it’s difficult to imagine what can come," she said. "But it’s so much easier for the first responders if they are actually able to deal in a community knowing who is there and who isn’t there."

The bottom line, Boucher said, is that even if residents decide to stay in their homes to try and brave the floodwaters, there may not even be enough rescue personnel to save them from danger. 

The Alberta government said that 25 communities were still under states of emergency as of Saturday afternoon.

Lethbridge lifted a state of local emergency for the city Saturday morning. The Oldman river peaked around 1 a.m. local time, and they city's website says water levels are receding "very slowly." The County of Lethbridge remains in a state of local emergency.


View a map of the evacuated areas

Alberta Emergency Services is expecting a number of bridges to be washed out. Travers Reservoir has been opened and historic high flows were reported in the Little Bow River.

It is expected that all bridge crossings on Highways 522, 845, 25, Cameron Crossing at TWP RD 11-2, Peacock Crossing TWP RD 13-0, and the Sundial Crossing RR 19-5/20-0 will be washed out.

Torrential rain last week — up to 200 millimetres in some places — as well as saturated ground and the local geography that encourages water to run downhill quickly were among a confluence of factors leading up to the devastation.

At least three people have died in the floodwaters. The RCMP reported Saturday that it had recovered the body of a woman whose mobile home was swept away Thursday. The bodies of another man and woman were recovered near flooded High River Friday.

With files from CBC's Susana da Silva