Flooded with miscalculations

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This article was published 17/04/2015 (3289 days ago), so information in it may no longer be current.

The province has admitted it miscalculated the volume of spring runoff from eastern Saskatchewan this year — a mistake farmers fear may cause up to 50,000 acres of land to go unseeded in western Manitoba.

Provincial officials stopped draining the Shellmouth reservoir on March 18, satisfied they wouldn’t have to contend with any great flooding this season along the upper Assiniboine River. Their concern was if they continued to drain the reservoir, there could be shortages of water for communities and irrigation this summer.

But by early April, flood forecasters realized they had misjudged how much water was heading Manitoba’s way.

And on April 7, 20 days after they had stopped releasing water from the reservoir, they turned the tap back on — releasing much greater amounts than before, flooding agricultural land south of the dam all the way to St. Lazare.

Earlier this week, they upped the release to 4,500 cubic feet per second (compared with 800 cfs during the winter).

Flooding along the Assiniboine, downstream of the dam, is now expected to continue until the end of the month — if the weather co-operates.

Steve Topping, a senior government official who supervises the province’s flood forecasting group, admitted this week that with more accurate forecast data, the province would have kept draining the reservoir.

“In hindsight, with a better understanding of the inflow forecast, Shellmouth operations could have been optimized to provide greater flood (control) benefits,” he said.

Farmers and ranchers along the river are livid. They don’t understand why the government stopped draining the reservoir when the province’s own forecasts in January and February stressed soil-moisture conditions were high and snow cover was above average out west.

Cliff Trinder, who ranches along the banks of the Assiniboine River near Russell, called the province’s flood forecasting “abominable.”

“They realized on the seventh (of April), the day after Easter weekend, that they were in trouble,” he said. “They cracked her open to 1,000 (cfs outflow from the reservoir) and they’ve been raising it since.”

He believes agricultural land immediately below the reservoir could have been spared flooding if the government had continued to release water from the Shellmouth during the three-week period.

Meanwhile, the big discharge from the dam will exacerbate the natural flooding that is occurring downstream, south of St. Lazare. There, the Assiniboine is flooding because of heavy flows from its tributaries, including the Qu’Appelle River.

Agricultural land is expected to remain flooded for weeks in an area extending to Grand Valley, just west of Brandon.

The miscalculation occurred despite ideal weather conditions. Snowmelt was gradual and there was only modest precipitation.

Topping said increased drainage in eastern Saskatchewan in recent years has made flood forecasting more challenging. He also said the province’s forecast models take into account temperature and snowpack, but not the effects of wind and humidity.

“Those are uncertainties that we can’t calculate for,” he said.

After initially worrying about potential flooding along the upper Assiniboine in January and February, Manitoba flood forecasters issued a rosy outlook in March.

Retired longtime flood forecaster Alf Warkentin said officials may have put too much stock into updated maps that showed little remaining snow cover in the area at the time they shut off outflows from the dam.

“Perhaps they did not realize that much snowmelt water was still sitting on fields and in ditches and was only delayed from reaching river gauges by cool weather,” he said in an email to the Free Press.

A formal review of the province’s forecasting efforts following the massive 2011 Assiniboine River flood found forecasters lacked the space, equipment and appropriate computer models to properly track runoff under certain conditions.

Progressive Conservative MLA Shannon Martin said the government has announced plans to invest in remote weather stations and new river-water measuring equipment, but it doesn’t seem as though it’s followed through with these intentions.

The 2011 flood should have been a wake-up call, he said, referring to criticisms of inaccurate forecasting that were levelled at the province at that time. “It’s pretty clear that the government is basically comatose on the file,” he said.

Martin also noted there have been recent changes at the top of the Infrastructure and Transportation Department, which includes the flood-forecasting unit. The former minister in charge, Steve Ashton, quit cabinet in late December to run for the NDP leadership. His duties were added to the responsibilities of Agriculture Minister Ron Kostyshyn. And the department’s deputy minister, Doug McNeil, recently left to become the City of Winnipeg’s new chief administrative officer. “You have to wonder if this isn’t having an impact from the top down,” Martin said.

larry.kusch@freepress.mb.ca