Flood control may determine Flathead Lake filling date

Flathead Lake is projected to reach an elevation of 2,890 feet by the end of May, and there is potential for the lake to be held just below its full pool elevation of 2,893 by June 15, the target date for the lake to be at full pool.

Representatives from PPL Montana, the U.S. Army Corps of Engineers, the Confederated Salish and Kootenai Tribes and the Bonneville Power Administration recently conferred about current and projected operations at Kerr Dam.

PPL operates the dam at the direction of the Corps, based on runoff forecasts, snowpack, weather conditions and other factors. The Corps pointed out that the snowpack above the Flathead Basin is at 148 percent of average, which may prompt the need for the lake to be held below full pool by June 15.

“Because of the potential for flooding as a result of above-average snowpack and the potential for localized precipitation, the Corps has instructed PPL that the lake elevation may need to be at a level less than full pool by June 15, which would be less full than in years with normal snowpack and precipitation,” a joint press release states.

The lake is currently at 2,888 feet, or nearly five feet shy of full pool, and outflows at Kerr Dam have been around 26,900 cubic feet per second.

The dam’s operations will be adjusted as the lake’s refill schedule develops.

“The timing of when Flathead Lake will achieve its full pool elevation of 2,893 feet is unknown at this time,” the release states.