Souris expected to behave this Spring

The National Weather Service issued a Flood Potential Outlook for the Souris River Basin Thursday morning. Projections show that runoff into the drainage basin this spring should be minimal with little to no chance of flooding along the upper reaches of the Souris River, including the Minot area.

However, the chances of reaching flood stage increase farther downstream.

Although the outlook is good news for flood weary residents located on or near the Souris, the projections are subject to revision in the event of heavy late winter snowfall, above average spring rainfall or a very rapid melt. The NWS says it will release updated Flood Potential Outlooks each Thursday beginning in March, if conditions warrant.

The Saskatchewan Water Security Agency will be issuing an updated runoff forecast for the Souris River in Canada in early March. According to a February issuance from the WSA, runoff into the Souris River Basin this spring is expected to be near normal. Winter precipitation over southeast Saskatchewan, which contains the Souris River and Moose Mountain Creek drainages, is currently below average.

Thursday’s outlook issued by the NWS states:

“The Souris River above Minot and the Des Lacs River are generally at near normal risk of minor flooding this year. However, downstream of Minot the relative risk of flooding increases along the Souris River itself, as well as the Wintering River and Willow Creek.”

According to the NWS, a significant factor with the potential to influence spring runoff in the lower reaches of the Souris is soil moisture content that is well above normal. A deep frost remains throughout much of the basin, meaning rapid runoff could occur and result in greater runoff than currently forecast. The Flood Potential Outlook says, “The greatest contributor to the spring flooding risk this year are early spring rains that can fall on frozen ground.”

At this time flows in the Des Lacs River are projected to be minimal. The NWS says the Des Lacs has a 90 percent chance of reaching 7.2 feet this spring and only a five-percent chance of reaching 15.7 feet. Major flood stage on the Des Lacs is 19 feet.

The river height at Minot’s Broadway Bridge is given a 90 percent chance of reaching 1,542.1 feet. Major flood stage there is 1,555.0 feet. The NWS says the Souris River has a 90 percent chance of reaching 1,500.1 feet at Velva where major flood stage is listed at 1,515.0 feet.

Farther downstream, where the river gathers momentum, the Souris is given a 90 percent chance of reaching 54.4 feet at Towner and 12.5 feet at Bantry. While those levels are above what is considered minor flood stage, they are below the major flood stage standards of 56.0 feet and 14.0 feet respectively. The Souris River at Westhope is given a 90 percent chance of reaching 12.6 feet where major flood stage is 16.0 feet.

The most troublesome areas, according to the Thursday outlook, could be the Souris tributaries of Wintering River and Willow Creek. The Wintering River joins the Souris near Karlsruhe. Current projections give the Wintering River a 90 percent chance of reaching 6.8 feet, within two-tenths of minor flood stage but below major flood stage of 16.0 feet. Willow Creek is given a 90 percent chance of reaching 13.4 feet, above minor flood stage of 7.0 feet but below the 16.0 foot major flood stage level.

Three well-known reservoirs influencing flows on the Souris have all been drawn down in accordance with the International Agreement governing their operations. On Wednesday Lake Darling in North Dakota stood at 1,595.95 feet, slightly below its 1,596 foot target level.

Saskatchewan impoundments Alameda and Rafferty were at 1,840.6 feet and 1,802.7 feet respectively, both below the maximum operating levels as stipulated by International Agreement. That level for Alameda is 1,840.64 and Rafferty 1,802.91 feet.

About 22 cubic feet per second of water is currently being released through a control gate at Lake Darling Dam. The amount of water entering the U.S. in the Souris River near Sherwood is about 15 cfs. The Souris flows into the north end of Lake Darling. Thursday’s outlook says the Souris at Sherwood is expected to remain well below flood stage this spring.