Arabnews24.ca:Wednesday 22 March 2023 05:45 PM: The Red River is now expected to spill its banks in several places in Manitoba this spring, but is not projected to rise high enough to threaten any communities protected by ring dikes.
Provincial flood forecasters raised the flood risk for the Red River from moderate to major on Wednesday, thanks to major snowstorms in recent weeks south of the border.
In its March flood outlook, Manitoba's hydrologic forecast centre said the storms that swept across North Dakota and Minnesota during the latter portion of the winter left behind more snow than usual across much of the U.S. portion of the Red River drainage basin.
As a result, the Red is expected to crest this spring at a volume similar to the 2019 flood, if weather conditions over the coming weeks are average.
If a lot of rain or snow falls in the coming weeks, the flood could approach the volume seen in 2020.
Both of those floods crested well below the level of the ring dikes that protect the communities of Emerson, Roseau River First Nation, Morris and dozens of others in Manitoba's portion of the Red River basin, a vast floodplain that's home to most of the province's population.
Manitoba's Highway 75, the main transportation link between Winnipeg and the United States, did not close in either 2019 or 2020.
That means the likelihood of a highway closure is very low this year, said Fisaha Unduche, executive director of Manitoba's hydrologic forecast centre.
Precisely how high the river gets depends on weather from now until the spring melt. If conditions are dry and the snow melts gradually, the flood risk along the Red River could be downgraded to moderate.
Under all scenarios, the Red is expected to spill its banks near Ste. Agathe, just south of Winnipeg, but won't come close to the community's ring dike.
The March outlook is a change from the first flood outlook for the season, which was published at the end of February. It predicted moderate flows along the Red River.
There is a low risk of significant flooding along Red River tributaries, including the Roseau, Rat and Pembina rivers.
The risk is moderate along the Assiniboine River and low on the Souris, its major tributary.
The Portage Diversion may nonetheless be used to prevent ice jamming on the Assiniboine River east of Portage la Prairie and to control river levels between Portage and Winnipeg.
The outlook also predicts a low risk of flooding along the Fisher and Icelandic Rivers in the Interlake. Ice-cutting along the Icelandic River was conducted in February to prevent jamming.
There is also a low risk of flooding for most other Manitoba basins, including the Saskatchewan River, Whiteshell lakes area and northern Manitoba.
Water levels are expected to remain below dikes at communities along those rivers.
Floodway to operate
The Red River Floodway is expected to be put into operation this spring to reduce water levels in Winnipeg.
With the floodway in operation, the Red is expected to crest between 17.5 and 19.5 feet above normal winter ice levels at Winnipeg's James Avenue, depending on the weather in the coming weeks.
That's in the low-to-moderate flooding range for the city. If river levels rise to the high end of that range, a handful of low-lying city properties may require sandbag dikes as a precaution.
When river levels are that high, there is an elevated risk of basement flooding during heavy rainstorms.
Ice-cutting along the Red River north of Winnipeg — conducted to prevent ice jamming — wrapped up in February.
The flood outlook calls for most Manitoba lakes, including Lake Winnipeg and Lake Manitoba, to remain within their recommended operating ranges after the spring run-off.
The exceptions are Lake St. Martin in the northern Interlake and Dauphin Lake in western Manitoba. Both are expected to remain above their recommended ranges well into the spring.
