The Assiniboine River is expected to crest today near Portage la Prairie, Man., as floodwaters from the river travel east toward Winnipeg and other communities.
Provincial flood forecasters believe river levels will peak in the Portage la Prairie area at around noon CT Wednesday.
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The provincial government is hoping to push much of the excess water through the Portage Diversion, a flood control structure, but it remains to be seen if that will be enough to protect more than 100 properties nearby.
Military and volunteer crews have been busy sandbagging homes in that area over the past several days.
Officials are warning homeowners along the river to prepare for water levels about 30 centimetres higher than record flood levels the area saw in 2011.
Dikes along the Assiniboine and the Portage Diversion will be pushed to the limit but a "dramatic mobilization" has helped prepare the province as much as possible for the crest of floodwater bearing down from the west, Emergency Measures Minister Steve Ashton said Tuesday.
Officials are waiting to see whether it will be necessary to cut through a road dike at the Hoop and Holler Bend in the Assiniboine to let the pressure off of the swollen river.
A significant crest of the Assiniboine is expected to reach the community of St. Francois Xavier 24 hours after the Portage Diversion crest, then the edge of Winnipeg just after that.
Hundreds of people have been forced from their homes since torrential rainstorms caused overland flooding in parts of southeastern Saskatchewan and southwestern Manitoba in late June.
Federal NDP Leader Tom Mulcair will visit a military flood relief post in Manitoba on Wednesday, three days after Prime Minister Stephen Harper toured flood-threatened areas.
Lake Manitoba residents on high alert
The 29-kilometre Portage Diversion channel directs water from the Assiniboine River near Portage la Prairie toward Lake Manitoba.
People living near the lake are preparing for the worst — high lake levels combined with strong winds that could breach their dikes.
The Rural Municipality of St. Laurent, which has declared a state of local emergency, says about 750 properties are at risk.
Municipal officials say the provincial government has not helped them out to date, so they have hired private contractors to put sandbags in areas most at risk.
"The province is not giving us the courtesy of answering our phone calls, of letting us arrange a meeting with them," St. Laurent Coun. Mona Sedleski told CBC News late Tuesday.
Area resident Claude Noble said he fears that the sandbagging efforts won't help, as it took just one windstorm in 2011 to breach the dikes.
"Is this going to happen every three years?" he said. "They said that's a [once in a] 300 year flood. Well, it's been a short 300 years."