With heavy rains persisting and waters still rising over much of waterlogged eastern Canada, the nation's military on Sunday tripled the number of troops urgently working to evacuate thousands of residents.
Montreal Mayor Denis Coderre declared a state of emergency for his city, allowing authorities to order mandatory evacuations from threatened areas.
"The next 48 hours will be decisive," Coderre told reporters.
Evacuations were ordered in Pierrefonds, on the northwestern shore of the island of Montreal, after three temporary dikes ruptured, sending water levels surging.
A combination of torrential rains and runoff from melting snow has caused rivers to overflow their banks from Ottawa to Montreal, posing critical challenges for people already exhausted by weeks of seemingly unending rainfall.
More than 1,000 people have been evacuated in Quebec province, the largest number coming from Gatineau, near Ottawa, the province's emergency response unit said Sunday.
More than 2,000 homes have been flooded and 140 towns and cities affected, with authorities urging residents to evacuate before it is too late.
In addition to Montreal, eight localities declared states of emergency.
But Quebec Premier Philippe Couillard warned the worst was yet to come.
"The water will continue rising over the next two or three days," he said Saturday after visiting the town of Rigaud, west of Montreal, which has been flooded for more than a week.
Water levels were rising across much of an area of some 500 kilometers (300 miles), from Toronto and Lake Ontario and stretching downstream along the St. Lawrence River.
The Ministry of Public Safety said waters were expected to crest sometime Monday in Quebec province.
Some 450 troops had been dispatched by Saturday to help put sandbags in place and assist with evacuations.
But that number was set to triple by the end of Sunday, including 500 in the immediate Montreal region, 400 in the area between Gatineau and Rigaud to the west, and more than 500 in the Trois-Rivieres region northeast of Montreal, said Lieutenant Colonel Pascal Larose.
Their tasks included evacuating residents, reinforcing dikes and protecting critical infrastructure such as water treatment plants and bridges, the ministry of defense said.
Prime Minister Justin Trudeau traveled Sunday to Terrasse-Vaudreuil, about 40 kilometers west of Montreal, to survey damage, a spokesman said.
Environment Canada warned that "the ground, already near saturation, has little ability to absorb further rainfall."
"Even shallow, fast-moving water across a road can sweep a vehicle or a person away," it said. "Don't approach washouts near rivers, creeks and culverts."
- Not seen since 1974 -
Pierrefonds resident Robert Robillard had yet to evacuate by Sunday, despite the 10 to 15 centimeters (four to six inches) of water in his basement.
"I haven't seen anything like this since 1974," he said, adding that the area now is much more crowded and thus vulnerable.
In Rigaud, Mayor Hans Gruenwald ordered the mandatory evacuation of some 100 homes. After three weeks of flooding, "our people no longer have the physical capacity or the morale, so I took the initiative to evacuate them," he told the LCN network.
Floodwaters have made 400 roads impassable, and several schools will be closed Monday.
School gymnasiums and other public buildings throughout the area have opened their doors to evacuees.
"I understand people are reluctant to leave their homes," Couillard said, "but if you're asked, do it for your own safety."
- Flooding out west, too -
Meanwhile, in British Columbia on the opposite side of the country, the same combination of rain and snowmelt has caused flooding and mudslides that left at least two people missing, including the fire chief of the village of Cache Creek who had been out checking water levels.
A 76-year-old man was missing after a mudslide Saturday swept away his home in the community of Tappen, CBC reported.
First responders rushed to the scene but were forced to pull back.
"It sounded like a freight train coming down the mountain," Tappen-Sunnybrae Fire Department Chief Kyle Schneider told the broadcaster.