More water for Souris
The U.S. Army Corps of Engineers announced Monday that the amount of water being released into the Souris River through the control gates at Lake Darling Dam has been increased to 700 cubic feet per second and that future increases are a virtual certainty. The release rate was 600 cfs last Friday.
According to the Corps, the plan is to increase Lake Darling outflows to 800 cfs in the next few days barring complications with ice conditions. Increased releases last week has weakened river ice along the Souris, leading to the possibility of ice jams once the surface ice begins to break apart.
In response, the National Weather Service in Bismarck is maintaining a Flood Warning for the Souris River in Ward County with an emphasis on the increased risk of ice jams and resulting fluctuations in river levels.
Although no property becomes endangered when the Souris reaches official flood stage at Baker’s Bridge north of Burlington, the river there is expected to reach 10.4 feet by Friday morning. Official flood stage at Baker’s Bridge is 10 feet. At 14.3 feet water begins to flow over the roadway crossing Baker’s Bridge and general flooding of the river valley occurs.
The current projected flows in the Souris are not unexpected or considered unusually high for the start of the runoff season. However, the releases are being conducted further in advance of the runoff season than what occurred during the historic flood of 2011. In that year the Corps closed the Lake Darling release gates on April 8 and then opened them to 2,400 cfs three days later.
Flood stage at Minot’s Broadway Bridge is 1,549 feet, a level that is is reached at approximately 5,200 cfs. While flows of that level can result in additional protection being placed at certain locations along Minot’s diking system, the majority of Minot’s dikes protect to a height of 1,552 feet or a flow of approximately 7,700 cfs.
The most current Probalistic Outlook issued by the NWS says there is only a 10 percent chance of the Souris reaching a height of 1,551 feet at Broadway Bridge in the coming weeks. The Souris peaked in Minot at 1,561.72 feet in 2011. A new runoff outlook is expected to be issued as early as next week, earlier if conditions warrant.
River gauges located where the Souris enters North Dakota from Canada, and at the Boy Scout Bridge located 4 miles northwest of Minot, have been climbing in recent days. The levels are well within the normal range for this time of year and are not causing any difficulties. The Sherwood gauge rise reflects the release rate from Rafferty and Alameda reservoirs in Saskatchewan. The Boy Scout Bridge increase is a result of additional flows through the gates at Lake Darling which mirror expected inflows.
According to the NWS, the water in the Souris at Boy Scout Bridge is given a 25 percent chance of reaching 14.5 feet. Official flood stage at that location is 14 feet.
At this time the greatest risk for river concerns remains an unstable ice pack and the possibility of unexpected fluctuations in river levels due to ice jams which could occur with little or no advance warning.