The 2011 flood fight in Winnipeg is officially underway, as rising river levels over the past weekend led the city to start building dikes with its stockpile of 1.8 million sandbags.
After a slow March melt, the Red River has risen roughly 10 feet in a week, increasing to 14.4 feet above normal winter ice level at James Avenue on Monday from only 4.7 feet seven days earlier.
The Red is expected to crest in Winnipeg somewhere between 20 and 23 feet James in May, provincial officials say.
The prospect of the river reaching 20 feet at James this weekend, however, led the city to announce 30 low-lying properties should have sandbag dikes in place by Friday, while another 80 should finish their dikes by Sunday.
All of these properties are on a list of 560 whose owners have already been warned their properties will require some form of protection from the city's rivers and creeks this spring.
Over the next two days, city officials will knock on the doors of the properties where sandbagging should begin right away, said Scott Payne, flood co-ordinator with the public works department.
Most of the properties in question are located in St. Norbert or along Kingston Row, said city flood-protection engineer Grant Mohr.
Once owners are ready, the public works department will deliver sandbags to these properties. It's up to homeowners to build their own dikes, but the city will assist with construction advice and also co-ordinate volunteer efforts, Payne said.
Anyone willing to volunteer may register by calling 311. Property owners who seek more information may also call 311 or visit www.winnipeg.ca/emergweb. Owners of the remaining 450 properties on the flood-protection list will be advised to build dikes when river levels rise even higher.
Monday also saw public works crews begin building sandbag dikes across public property as part of an effort to raise approximately five kilometres of dikes across the city.
Dike construction could not begin sooner because overnight temperatures were below zero. Frozen sandbags are not sufficiently malleable to form waterproof seals. Freezing may also damage sandbags.
River levels rose dramatically in Winnipeg over the past week because of a combination of warm weather on Saturday, rain on Sunday and the continued presence of ice on the Red River, Mohr said.
Once the ice dissipates ---- likely over the next week or two -- river levels may plateau or even decline temporarily, Mohr said.
The Red River Floodway will also moderate the increase in river levels, said Steve Topping, executive director of Manitoba Water Stewardship.
Once the Red reaches 18 feet at James -- something that may happen as soon as Thursday -- it will begin spilling into the floodway, even without the operation of the floodway control structure, Topping said.
The floodway control structure won't be operated until ice is moving freely through the river, he added.
The Red River is rising along its entire length. In Fargo, N.D., it rose to 25.5 feet Monday and may continue rising as high as 38 feet by April 11, U.S. forecasters predicted Monday.
The National Weather Service estimates there's a 50 per cent chance the Red will exceed 40.5 feet at Fargo by the time it crests later this month. The record crest in the North Dakota city, set in 2009, was 40.82 feet. Fargo is planning to protect itself from a 42-foot crest.
The Red River may begin spilling its banks in Manitoba around Letellier next week but a crest likely won't reach Emerson until April 29 to May 5, Topping predicted.
The crest could reach Winnipeg between May 6 and 13, added Topping, qualifying that prediction as "an educated guess."
The prolonged flood fight increases the period during which Winnipeg is vulnerable to sewer backups, as the city's drainage system could wind up overwhelmed if an extreme downpour hits while river levels remain high.
The city will begin sealing manholes next week to reduce the possibility of sewer backups, Mohr said.