Lake Darling to be lowered
In the wake of the first Spring Runoff Outlook issued by the Saskatchewan Water Security Agency, Lake Darling will be lowered below its prescribed operating level in preparation for snowmelt runoff.
Frank Durbian, Souris River Basin Complex manager, says the current operating plan is to draw down Lake Darling well below its normal spring operating level of 1,596 feet. The decision is a change from how the reservoir has been managed previously, something many people have urged since the historic flood of 2011.
“By the end of March our plan is to lower Lake Darling to 1,594 feet,” said Durbian Wednesday. “We’ll gain two feet of storage to accommodate spring runoff. Today we increased releases to 160 cubic feet per second. Every four or five days we will increase that by 50 cfs as we slowly ramp up. We expect a max flow in the next few weeks of 400 cfs.”
According to Durbian, the increased releases will put Lake Darling at or very near the 1,594 level by the end of March.
“We’ll evaluate ice conditions on the river as we go,” explained Durbian. “At this point this won’t result in any major break-up of ice, rather the ice should slowly melt away on the river as we raise releases.”
Durbian said he “highly recommends” people planning to be on the river’s ice in the days ahead to “consider whether or not to be on the ice at all.”
The Saskatchewan Water Security Spring Runoff Outlook issued Wednesday does not contain any alarming runoff numbers for the Souris River at the Sherwood Crossing upstream from Lake Darling. It does note however, that the snowpack along the Souris River Basin is significant in certain areas.
“The snow water equivalent confirms that the heaviest snowpacks in the basin are located below the Saskatchewan reservoirs,” states the report. “Snowfall in December across the southeastern portion of the Souris River Basin in Saskatchewan was well above average, with record December accumulations observed at Estevan.”
However, as has been the case in the Minot region, January snowfall was well below average in the Estevan, Sask. region. All three southern Saskatchewan impoundments are at or below their operating levels as prescribed in the International Agreement.
Preliminary plans, states the outlook, calls for allowing Boundary Reservoir to fill to its summer operating level and divert any additional runoff into nearby Rafferty Reservoir. By utilizing diverted flows from Boundary Reservoir it is expected that Rafferty will reach its summer operating level. Both reservoirs are located near Estevan. Boundary is located on Long Creek and Rafferty on the Souris River.
The Water Security Agency says it will continue to draw down Alameda Reservoir near Oxbow, Sask. even though the reservoir is currently below its prescribed operating level. Releases from Alameda will be re-evaluated based on the next Spring Runoff Outlook scheduled for Feb. 15. The preliminary operating plan for Alameda is to store all inflows until the reservoir fills to its normal operating level.
The next runoff outlook for the Souris River Basin issued by the National Weather Service will be on Feb. 16. The International Souris River Board, which is comprised of professionals from both the United States and Canada, is scheduled to meet in Regina, Sask., Feb. 23. At that meeting all available information regarding snowpack, soil conditions, snowmelt and weather forecasts will be evaluated before the ISRB determines whether or not 2017 will be considered a 1-in-10 runoff event. If so, the basin will undergo flood operations and the U.S. Army Corps of Engineers will determine release rates from Lake Darling Dam.