Kalispell, MT March 9, 2021—The Flathead National Forest is seeking public input on a proposal to conduct repairs on the Lion Lake Dam.
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. This leak could lead to dam failure and have impacts to Whelp Creek, a tributary to the South Fork of the Flathead River.
Proposed activities include: 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 would start draining the lake in May 2021. When the lake is drained for dam repairs some water would remain in the lake; however, we cannot determine how deep or large of a body of water will remain. While repairs are taking place, the north and south dams will be closed for public safety. We would endeavor to keep public access open in two locations: the north recreation area and the existing pull-outs along Montana State Route 895.
The anticipated construction start date would be August 2021 with completion in October 2021. When repairs are complete, we would begin refilling the lake. It is unknown how long it would 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.
Based on preliminary analysis, the Flathead National Forest believes this proposal falls within a category of actions listed in the Forest Service National Environmental Policy Act Handbook that are excluded from documentation in an environmental assessment or environmental impact statement under 36 CFR 220.6(e)(18).
Additional information and maps for the project can be found on the Flathead National Forest website at https://www.fs.usda.gov/projects/flathead/landmanagement/projects. The Forest will update the website with additional information about the status of the project when it becomes available. The public should submit comments by April 7, 2021 to comments-northern-flathead-hungry-horse-glacier-view@usda.gov. For questions, please contact Project Leader Jennifer Brady at (406) 758-5210 or jennifer.brady@usda.gov.
