December 23, 2025
Helicopters could be ferrying construction materials to Eightmile Lake by next fall.
Design of the replacement dam should be finished this coming spring. If the state's Dam Safety Office approves the final design and issues a construction permit, and other agencies grant all other required permits, helicopters could be staging materials at the lake by autumn. The goal would be to start construction the following year.
Access to the site will only be by foot or helicopter. The Forest Service is not allowing vehicles or any temporary road into the Alpine Lakes Wilderness.
Construction will need to be completed in one season, engineers explain, which is a fairly short window of time. Once they start, the first step would be to remove the existing dam and excavate below the current lake bottom near its outlet to insert a valve and pipe. Accumulated natural debris at the outlet has always leaked, so other steps will be needed to stabilize the dam's foundation. Then workers would build the dam itself. Because of the short season at that elevation, the plan is to move in as much material as possible beforehand, even though space at the lake is limited. As soon as the snow melts in 2027, construction would start.
The amount of concrete required has been a big concern, mainly because of the cost of a helicopter to transport so much of it. The nearest ready-mix plant is in the Wenatchee valley. Engineers considered the option of a temporary batch plant at Eightmile Lake. A batch plant mixing concrete within a designated wilderness would have raised serious issues.
The planned solution now is to insert light-weight vinyl sheets into the dam. They would reduce how much concrete is needed and supposedly have the same strength. The Dam Safety Office has apparently approved this option.
Because of the time needed for permitting and staging, one engineer admits, "It's hard to stick to a specific schedule." But this is the general plan.
Questions about the need for a Forest Service special use permit obviously could affect this.