Se̓liš Ksanka Ql̓ispe̓ Project and Flathead Lake level updates
Energy Keepers, Inc. Monthly Operations Update:
Flathead Lake levels and Kerr Dam outflows
by James Conner for the Flathead Lakers
Flathead Lake’s outlet channel is narrow and shallow. At low lake levels, the rate of outflow is less than the 15,000 cfs capacity of Kerr Dam’s turbines. When Flathead Lake reaches 2885.80, the discharge from the lake matches the dam’s turbine capacity. As the lake rises higher, the channel’s capacity increases, as displayed by the graph below and the Excel table (click here to download table).
If the inflows to Flathead Lake are greater than the outflows, the lake rises. During the spring runoff (usually May through June), the inflows to the lake can be much greater than the outflows, even when Kerr Dam is wide open and not holding back any water.
That last happened in 1964, when the great flood in early June pushed the lake to 2894 for a week. During that flood, the Flathead River peaked at 176,000 cfs, and would have peaked at more than 220,000 cfs had not the South Fork’s flows been stored in Hungry Horse Reservoir.
The lake will rise one foot in one day with net inflows of 64,000 cfs. Smaller net inflows fill the lake more slowly.
Links to Streamflow, Snowpack, and Flood Information
Northwest River Forecast Center River Conditions Summary for the Flathead River and its 3 forks
Northwest River Forecast Center Peak Flow Forecasts – Flathead River at Columbia Falls
National Weather Service Hydrologic Outlook – Flathead River at Columbia Falls Stage Height
Flathead Watershed Sourcebook: Floods, Flooding Effects on Flathead Lake, Analyzing Flooding