Average to above average snow in the mountains bodes well for a healthy supply of water for Lake Diefenbaker this summer.
Doug Johnson, director of basin operations for the Saskatchewan Watershed Authority, expects the lake to be at levels lower this June than last year.
“We are moving as much water out of Lake Diefenbaker as we can now,” he said, noting it is now filled to capacity for hydroelectric use.
In 2005, four major rainfalls in Alberta generated the highest runoff into Lake Diefenbaker for June since the dam was built.
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That caused flooding in low-lying areas in the Moon Lake district near Saskatoon, amounting to as much as a metre of water covering some agricultural lands.
Johnson explained the 2005 forecast estimated below normal mountain runoff, so the authority kept the lake high to ensure enough water for the various users.
“Without the rain, Diefenbaker would have been two metres lower than normal,” he said.
Johnson explained how the authority operated in a conservation mode until June 1. When the skies opened up, it was forced into flood operations instead.
Cumberland House was the most seriously damaged, with the community evacuated and fishing, outfitting and wild rice operations affected.
In the Moon River valley, Bill and Lynn Lemisko faced crop losses and flood damage. They sought compensation from the authority for losses from last year’s market garden crop and the potential loss of perennial crops like asparagus and raspberries.
They argued the dam was not operated responsibly and that the watershed agency did not follow its own policies, procedures and guidelines in balancing water supply and flood protection interests.
In an Aug. 9 letter to David Forbes, minister responsible for the agency, they wrote: “While it might be argued that high water elevations in Lake Diefenbaker were not the primary cause of flooding, there is no doubt that the decisions made by watershed authority personnel during the events of 2005 did lead to the flooding.”
They say keeping the reservoir higher than normal and not discharging that water, combined with hoping for no further major rainfalls, led to a release of water that breached riverbanks.
“Because they gambled in favour of water supply over flood protection in the first place, they had to discharge water at the rate of 1,760 (cubic metres per second) when the next inflow came in from Alberta. It was this discharge that led to the flooding of cropland in the Moon River valley area.”
Sask Watershed held a public meeting with area residents last June to explain the South Saskatchewan River flood situation and dam and reservoir operations.
The authority maintains the dam was operated prudently in April and May and that it and the lake provided significant flood protection, with crop insurance coverage also available to farmers.
“As long as we don’t make the situation worse, then we don’t have a liability,” Johnson said.
