Power outages in the Canadian oil capital of Calgary could last for weeks or even months, city authorities said, as record-breaking floodwaters moved downstream to threaten smaller communities in southeastern Alberta.
Even as officials told 65,000 Calgary residents on Sunday they could start returning to their water-damaged homes, 10,000 people were evacuated in Medicine Hat, where the South Saskatchewan River is expected to burst its banks.
CF Industries said it was temporarily halting production at its Medicine Hat facility, Canada's largest nitrogen fertiliser complex, as a precautionary measure.
The floods have closed some rail lines and the east-west Trans-Canada Highway, and displaced more than 100,000 people.
The floods already look much worse than those of 2005, which caused C$400 million (HK$2.94 billion) in damage. Three people have been confirmed dead.
But officials say it is too early to put a figure on the damage in the western Canadian province and in Calgary, its largest city, with a population of 1.1 million.
"It will certainly be at least the middle of the week before people will be going back to work. There are some pockets of downtown where normality will not return for weeks," said Calgary Mayor Naheed Nenshi.
"We have turned a corner. We are still in a state of emergency, but our hearts and thoughts and prayers are now with our colleagues downstream."
Bruce Burrell, director of the Calgary Emergency Management Agency, said it could take days, weeks or perhaps even months to restore all power in the downtown core, where many of Canada's oil companies have their headquarters. Many of the firms were making plans for employees to work from home.
Heavy rain was blamed for 750 barrels of synthetic oil spilling from a pipeline 70 kilometres south of the oil town of Fort McMurray, in northern Alberta, early on Saturday. Enbridge, Canada's largest pipeline company, said the cause of the spill was still being investigated but unusually heavy rain may have resulted in ground movements that affected the pipeline. The oilfields were not threatened by the floods.
Enbridge shut down two other major oil pipelines serving Canada's oil sands region as a precaution. Canada is the biggest supplier of energy to the United States.
Jeff Burke, president and CEO of insurers Western Financial Group, said many Canadian homeowners would not be covered for damage resulting from flooding. "There is no flood insurance in Canada, so people do not have coverage for this. Where there's some coverage in some cases is if they have sewer back-up cover," Burke said.
"Just looking at water levels, what we have experienced and the destruction is much more severe now than in 2005."
The floods followed 36 hours of unusually heavy rain that pushed the volume of water in rivers to record levels. Some communities received six months of their normal rainfall in less than two days.