An analysis of current conditions across the Souris River drainage in southern Saskatchewan concludes the 2020 runoff season will be well below the minimal requirements that would initiate flood operations throughout the system.

That was the message delivered by the Water Security Agency in Saskatchewan in their initial Souris River Basin Spring Runoff Outlook issued this week.

The outlook noted that fall precipitation across much of southern Saskatchewan, where the primary drainage of the Souris River is located, was roughly 150-200% of normal but that snowpack and winter precipitation in the same area has been “well below average.”

The outlook states that “visual observations indicate little snowpack across the basin.” The National Weather Service has not flown the area to gather data on the snow cover, nor has the Water Security Agency conducted manual snow surveys. NWS estimates using satellite data suggest there is only slightly more than one inch of snow water equivalent on the ground throughout the basin, far less than what would raise concerns of a possible high runoff season.

Some uncertainty remains in the outlook and conditions can change in the event of a major snowfall or rainfall prior to or during the runoff season, but the outlook says “runoff yields are expected to be near median to slightly above normal for all forecast points.”

Flood control operations under the 1989 International Agreement between the U.S. and Canada are triggered when runoff expectations reach the level of a one-in-ten-years event. Based on the latest information available to the WSA, runoff on the Souris River where it enters North Dakota near Sherwood is expected to only reach 1-in-5 years of runoff.

Reservoirs on the Souris are all well within compliance of the International Agreement, including Lake Darling. Lake Darling is the final reservoir on the Souris and located approximately 20 miles northwest of Minot. At mid-day Wednesday the water level of Lake Darling was 1,595.96 feet. Its Feb. 1 drawdown level, as stipulated in the International Agreement, is 1,596 feet.

The largest of the Saskatchewan reservoirs on the Souris River drainage is Rafferty Reservoir near Estevan. On Feb. 1 Rafferty was at an elevation of 1,801.79 feet versus the 1,802.91 requirement. Grant Devine Lake near Oxbow, primarily fed by Moose Mountain Creek and which can release water into the Souris, was at 1,840.64 feet Feb. 1, the exact target level of the International Agreement.

A third and much smaller reservoir, Boundary, also located near Estevan, was at 1,836.05 feet Feb. 1, well below its full supply level of 1,840.08 feet. Boundary is a power plant reservoir on Long Creek. Excess water from Boundary can be released into an outlet channel flowing into Rafferty Reservoir or downstream into Long Creek that then enters the Souris.

According to the WSA outlook, Rafferty Reservoir is not projected to reach its preferred summer operating level but Grant Devine will. Also, states the report, due to very low projected runoff “no pre-runoff drawdown is required” for any of the Saskatchewan reservoirs on the Souris River drainage.

The NWS is expected to release a new Souris River Flood Potential Outlook next week. The January NWS outlook showed little chance of high water concerns on the Souris in North Dakota with the possible exception of a few location far downstream of Minot.