The Flathead National Forest has approved a project to conduct repairs on the Lion Lake Dam this summer.
Recent surveys and evaluation of the dam resulted in discovery of leakage occurring through the structure and declining integrity of the primary dam on the south side of Lion Lake. These leaks could lead to dam failure and have impacts to Whelp Creek, a tributary to the South Fork of the Flathead River. A request for public comment was sent out on March 8, 2021; one comment was received on the proposal.
In order to fix the dam, the following repairs have been approved: draining the reservoir to the level of the outlet pipe on the primary dam at the south side of the reservoir; slip-line the existing outlet pipe on the lake side of the dam; remove saturated fill; install a chimney and toe drain to handle seepage; remove existing outlet pipe headwall; replace outlet pipe on downstream side of dam; rebuild dam to a 2 ft higher crest elevation; replace outlet gate; rebuild dam embankment; and place riprap on shore to prevent wave erosion.
To reduce the lake level to the elevation necessary to allow dam repairs, we will start draining the lake immediately. While repairs are taking place during August, September, and October the north and south dams will be closed for public safety. Access to the lake will remain available at the north recreation area and the existing pull-outs along Montana State Route 895.
Completion of repairs is expected by October 2021. When repairs are complete, we will begin refilling the lake. It is unknown how long it will take for the lake water to return to its current elevation, however, lake levels and recreation access is expected to be back to normal for the 2022 summer season.
More information about the project can be found on the Forest’s website.