After more than 200 millimetres of rain in less than 72 hours, a dam in western Manitoba may be at risk.
In a news release, issued Canada Day evening, the province announced that Rivers Dam could suffer a “structural failure.”
“The Manitoba government does not have confidence in the Rivers Dam. The dam is facing unprecedented flows on the Little Saskatchewan River following heavy rains over the past few days,” the province said.
The government is advising about 35 property owners downstream of the dam to evacuate and to move their livestock to higher ground.
The Rivers Dam is located on the Little Saskatchewan River, 40 kilometres northwest of Brandon. The Little Saskatchewan originates in Riding Mountain National Park and meanders south, passing through the communities of Minnedosa, Rapid City and Rivers, before joining the Assiniboine River west of Brandon.
The Assiniboine should be able to handle the additional flows from the Little Saskatchewan, the province said.
“Flooding of low-lying areas is expected for most portions of the Assiniboine River and its tributaries. However, water is expected to remain below flood protection levels at most locations along the Assiniboine and Souris rivers.”
Ron Krahn, who farms near Rivers, said on Twitter that the lake created by the dam is 1,600 acres and the dam height is 50 to 60 feet.
The dam is about 60 years old.
So much water is passing over the dam’s spillway that’s it difficult to see the bottom of the spillway, said Manitoba infrastructure minister Ron Schuler.
“This (warning) is being done out of an abundance of caution. We cannot take chances with this incredible amount of water creating tremendous pressure on the Rivers Dam,” Schuler said in a Canada Day teleconference with media.
The dam is at risk because a massive amount of rain has fallen on the region north of Brandon since June 28. The first two storms, on Sunday, dumped 120-160 mm of rain on Minnedosa and farmland upstream from the Rivers Dam. Another storm, June 30, produced an additional 40-60 of precipitation.
The topography between Brandon and Riding National Park is rolling land. The majority of the rainfall ran off farmland and quickly flowed into the Little Saskatchewan.
“We’re losing acres in low spots, but it seems to be running off so fast, or had ran off so fast, that a lot of the crop on higher ground looks surprisingly good…. The extent of moisture that actually went into the soil profile is certainly not the six, seven or eight inches that some areas received,” said Angela Brackenreed, Canola Council of Canada agronomist, who farms near Minnedosa.
Brackenreed made those comments prior to the June 30 storm. The additional precipitation could put more crops at risk.
“The concern is you get some anoxic (no oxygen) conditions and really stall out root growth,” Brackenreed said, referring to canola crops in the region.
The failure of the Rivers Dam is the major concern, right now, but farmers in the region are also coping with washed out roads and limited access to cropland.
Little Saskatchewan River has cut out both ends of Kirkhams Bridge NW of Brandon. Water has tunneled under the ends, not safe to walk over.@thebrandonsun @ebrandonca @QCountry91_5 #westman #storm pic.twitter.com/mgd44M4Pq6
— Ron Rabe (@Aggeez28) July 1, 2020
Municipalities and the province will need to repair dozens of washed out roads this summer and replace many, many culverts.
“The culverts you thought were quite safe, are gone,” said Dan Mazier, who farms northeast of Brandon and is the MP for Dauphin-Swan River-Neepawa.
“They weren’t designed for any of this kind of water.”
Harvest is only 55 to 70 days away, depending on the crop. Repairing all the destroyed culverts and washed out roads in the region, in two months, may not be possible. Farmers may have to take much longer routes, to truck grain back to the yard.
“There will be some challenges, that’s for sure,” Mazier said.
Severe winds during the June 28 storm, knocked over grain bins and damaged other farm buildings.