Release gates that have been closed at Lake Darling Dam will open to 1,000 cubic feet per second or slightly more today. The gates remained closed during the recent snowmelt to keep river levels to a minimum.
The U.S. Army Corps of Engineers, the agency responsible for regulating flows through Lake Darling during the current runoff season, originally planned to resume releases from Lake Darling on Tuesday. However, the timing of the releases was pushed back to today to allow more time for local runoff to recede downstream of Lake Darling.
Lake Darling remained encased in ice but was on the rise Tuesday, reaching a level of 1,593.24 feet after being dropped a few days ago to slightly below 1,592 feet. Inflow to Lake Darling is estimated at 1,500 cubic feet per second and increasing. The National Weather Service projects that a flow of more than 5,000 cfs will occur at the Sherwood gauge on the Souris River as early as Saturday and that similar flows, perhaps boosted by additional runoff, will enter Lake Darling.
"We have a forecast for Sherwood right now pushing to 22.5 feet this coming weekend, a little more than 5,000 cfs," said Allen Schlag, NWS hydrologist in Bismarck.
The record high at Sherwood occurred in 2011 when the river reached 28.16 feet. A level of 22 feet or more has happened only 11 times in recorded history. A difference this year from previous high flows is that the peak should be of short duration, perhaps only for a few hours.
The expected peak at Sherwood comes as a combination of local snowmelt runoff and releases of approximately 1,750 cfs from Boundary Dam near Estevan, Sask. Long Creek, which flows into Boundary, surged unexpectedly over 4,000 cfs during the recent melt. The excess water was released into the Souris. Long Creek flows have been declining and no further rises from snowmelt are anticipated.
Snowmelt on the Canadian side of the border is expected to get under way as early as Thursday and perhaps even reach a conclusion by early next week. Release gates at Rafferty Reservoir on the Souris near Estevan, and at Alameda Reservoir on Moose Mountain Creek near Oxbow, are scheduled to remain closed during the time of the Canadian melt. Both reservoirs are believed to have enough storage to capture runoff. Once the Saskatchewan reservoirs reach their summer operating levels excess water will be released into the Souris and make its way to Lake Darling.
"We're hoping to keep at or below anything currently experienced along the Souris," said Schlag. "Any rainstorms could change all that, but we're not expecting to exceed anything we've seen this year."
The NWS continued a Flood Warning for several locations along the Souris Tuesday, including Logan, Sawyer, Velva, Towner and Bantry where moderate to major flooding is forecast.