Flathead Lake Data

The overall water supply forecasts for May to September decreased slightly, mostly for May and June. Due to continued dry basin conditions, project outflows are historically low. However, with the recent precipitation and cooler weather the lake is on track to fill within the top foot by early to mid-June.

SKQ project outflows and the Flathead Lake elevation are dependent on many variables including lake inflows, weather, the demand for electricity, and non-power constraints such as the downstream fishery and flood risk management needs.

The overall water supply forecasts for May to September increased slightly, mostly increasing streamflow forecasts for May and June. Due to continued dry basin conditions, coordination with the U.S. Army Corps of Engineers on May 14, 2024 allowed EKI to begin refill of Flathead Lake with minimal impacts to flood risk. Under normal conditions flood risk management requires Flathead Lake being below 2890’ at the end of May.

SKQ project outflows and the Flathead Lake elevation are dependent on many variables including lake inflows, weather, the demand for electricity, and non-power constraints such as the downstream fishery and flood risk management needs.

The water supply forecasts did not change much this week. Due to dry conditions, coordination with the U.S. Army Corps of Engineers will allow EKI to operate Flathead Lake up to 2892’ feet in order to increase the likelihood of Flathead Lake refilling into the top foot in June with minimal impacts to flood risk. Under normal conditions flood risk management requires Flathead Lake being below 2890’ at the end of May.

SKQ project outflows and the Flathead Lake elevation are dependent on many variables including lake inflows, weather, the demand for electricity, and non-power constraints such as the downstream fishery and flood risk management needs.

The water supply forecasts for April to September dropped nearly 7%, mostly decreasing streamflow forecasts for the month of June. Due to dry conditions, coordination with the U.S. Army Corps of Engineers will allow EKI to operate Flathead Lake below 2892’ feet in order to increase the likelihood of Flathead Lake refilling into the top foot in June with minimal impacts to flood risk. Under normal conditions flood risk management requires Flathead Lake being below 2890’ at the end of May.

SKQ project outflows and the Flathead Lake elevation are dependent on many variables including lake inflows, weather, the demand for electricity, and non-power constraints such as the downstream fishery and flood risk management needs.

Due to dry conditions, as was the case in 2023, EKI has again coordinated with the U.S. Army Corps of
Engineers to operate Flathead Lake up to 2885′ in order to increase the likelihood of Flathead
Lake refilling into the top foot in June with minimal impacts to flood risk. Under normal conditions flood
risk management requires Flathead Lake being drafted as low as reasonably possible on April 15th.

Both weather and streamflows are highly uncertain. A warm and rainy event can rapidly increase
streamflows in the spring, and similarly a cold and dry event can keep the streamflows quite low
compared to normal. Temperatures, precipitation, and snowpack conditions such as density, all play a
part in determining how high or low stream flows move as well as the timing of the runoff.  If an early
runoff is detected, EKI will coordinate additional flood risk management deviations with the USACE as
needed to refill the lake.

SKQ project outflows and the Flathead Lake elevation are dependent on many variables including lake
inflows, weather, the demand for electricity, and non-power constraints such as the downstream fishery
and flood risk management needs.