Manitoba cities fortify flood defences before next deluge By: Chris Kitching Posted: 7:00 PM CDT Tuesday, Apr. 26, 2022 Last Modified: 7:42 AM CDT Wednesday, Apr. 27, 2022 Updates

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Municipalities grappling with overland flooding are ramping up preparations to protect buildings from another deluge, as a Colorado low threatens to dump more rain and snow on southern Manitoba.

Staff in cities and towns were busy filling sandbags, getting water pumps ready and inspecting dikes Tuesday, while forecasters said the storm could bring large amounts of precipitation starting Friday and through the weekend.

In Altona, about 100 kilometres southwest of Winnipeg, the curling rink had been turned into a sandbag station, with staff and volunteers aiming to fill 4,000 by the end of the day.

“It’s better to have some in a pile now instead of scrambling on Saturday afternoon,” said Mayor Al Friesen.

The town has Tiger Dams, large tubes that are filled with water to create a flood barrier, on standby, after last weekend’s rain overwhelmed its drainage system and seeped into basements.

In Winnipeg, city staff are working around the clock to clear debris from ditches, catch basins and culverts, and to move water through sewer and drainage systems, said spokesman David Driedger.

Staff will likely fill up to 30,000 sandbags per day in the coming days, he said.

As it makes similar preparations, the City of Selkirk has put contractors on standby in case it needs help pumping spring floodwater, said spokeswoman Vanessa Figus.

“We’re hoping for no more rain,” she said.

Transportation and Infrastructure Minister Doyle Piwniuk said the province is working with municipalities to make sure they are prepared and have flood-protection equipment such as sandbag machines.

He said the ring dike in St. Adolphe, located next to the rising Red River south of Winnipeg, is being closed, while a partial closure is planned for one in Brunkild. In Morris, workers prepared to erect a large earthern ring dike on Highway 75 in the event it’s needed.

The province is monitoring Highway 75 in case it needs to be closed, said Piwniuk.

“We’re hoping for no more rain.”
– City of Selkirk spokeswoman Vanessa Figus

An overland flood warning is still in effect for parts of southern Manitoba. Flood warnings are in place for the Red River between Emerson and the floodway inlet just south of Winnipeg, and the Assiniboine River between St. Lazare and Griswold.

Lakes in the Whiteshell area are under a high-water advisory, as levels on most lakes continue to rise due to rainfall and snow melt, the province said.

Natalie Hasell, a warning preparedness meteorologist with Environment Canada, is tracking two systems — an Alberta low, which could affect Manitoba on Thursday, or peter out before it gets here, and a Colorado low expected to arrive in waves, starting Friday.

With the ground still frozen, any rain will be runoff, she said.

“This will only make things worse — adding water to a system that is already quite overwhelmed,” said Hasell.

On Tuesday, weather models still disagreed on the Colorado low’s course and potential impact. Precipitation amounts could vary widely, with some models predicting 50 mm or more and others forecasting less, said Hasell.

She said precipitation in the Winnipeg area will be in the form of rain, while a mix of rain and snow could fall in southwestern Manitoba.

The Colorado low could bring thunderstorms, strong winds and a chance of freezing rain, said Hasell.

Scott Kehler, president and chief scientist of Weatherlogics, said some models show the storm missing Manitoba.

Forecasters will have a clearer picture by Thursday, he said.

Kehler said the Colorado low may not bring as much precipitation as the one last weekend, which dumped 76.6 mm in Altona and 70.5 mm at The Forks in Winnipeg.

Amounts could be between 15 and 25 mm in the Red River Valley and 25 to 40 mm in southwestern Manitoba, he said.

“For those areas with flooding (already), it will likely worsen things,” he said.

In its latest flood bulletin, the province said water levels in the Red River basin are at peak and staying steady or slowly declining after two days of rapid increases.

Levels on the Red continue to increase, but the rate has slowed “significantly.”

Jay Doering, a flood expert and professor of civil engineering at the University of Manitoba, said he expects sections of the Red and Assiniboine rivers to start breaching their banks within days.

“It was extremely stressful. If there was (a breach), 1,000 people would have had to have been evacuated.”
– Winkler Mayor Martin Harder after culverts beneath Highway 32 buckled under the force of running water late Monday night

The current worst-case scenario for the Red River Valley is a flood comparable to 2011, which would force some communities to close their ring dikes, he said.

“Depending on how much precipitation there is (this weekend), that water could begin to encroach on the upper levels of these ring dike communities,” he said.

U.S. National Weather Service warning co-ordination meteorologist Greg Gust said the Red is expected to crest at 50 ft. at the Canada-U.S. border May 5.

That would be the seventh-highest crest on record for Pembina, N.D., and about half a foot lower than the flood of 2020, he said.

“It’s a typical high-end moderate to major flooding scenario,” he said.

The record of 54.94 ft. was set in 1997.

Gust warned the crest could be higher if the Colorado low brings heavy rain.

Disaster was averted in Winkler after culverts beneath Highway 32 buckled under the force of running water late Monday night.

The damaged culverts blocked the flow of water, causing it to back up into an open field and rise against a dike, said Winkler Mayor Martin Harder.

Winkler sent potential evacuation notices to residents, as crews worked into the early hours Tuesday to pump water and clear the blockage.

“It was extremely stressful,” said Harder. “If there was (a breach), 1,000 people would have had to have been evacuated.”

He is concerned about the potential for more rain and snow melt on an escarpment about 30 kilometres west of Winkler.

“If we get a couple inches of rain this weekend, and that water comes down (the escarpment), it’s going to be tough,” he said. “We have no place to go with the water, other than the natural flow.”

Temperatures are set to rise across Manitoba, with Environment Canada predicting daytime highs of 8 C on Wednesday and 12 C over the weekend in Winnipeg.

Forecasters said a break in the rain and cooler weather brought a reprieve after the weekend deluge, as the effects of the last storm were still being felt.

Thousands of Manitoba Hydro customers in the Dauphin were still without power Tuesday after ice brought down lines and poles over the weekend.

— with files from Danielle Da Silva

chris.kitching@freepress.mb.ca

Twitter: @chriskitching