If conditions at a dam under our jurisdiction prompt an emergency declaration or the involvement of local/state emergency response staff, we track it here. This does not necessarily mean that a failure is imminent. In these cases, we work with local emergency management and the dam owner to take steps to reduce the risks posed by the dam.
Eightmile Lake Dam
Dec. 4, 2018
We are providing technical and regulatory support to reduce the risk posed by Eightmile Lake Dam in Chelan County. The dam is 90 years old and located in the Alpine Lakes Wilderness. After a 2017 wildfire, the area was left vulnerable to erosion, flash flooding, and possible dam failure. In spring 2018, the Chelan County Department of Emergency Management declared an emergency and led the response effort to notify local residents. Other involved agencies included the U.S. Forest Service and the National Weather Service.
The owner of the dam, the Icicle-Peshastin Irrigation Districts, completed repairs to the dam in summer 2018, including reshaping and armoring the dam crest and replacing part of the low-level outlet pipe. There is currently no elevated threat from the dam. We also installed monitoring equipment around the dam and conditions are normal.
Eightmile Lake Dam before initial repairs (left) and after (right) in summer 2018. The dam owner removed woody debris, cut down part of the rock-masonry spillway wall, reshaped the crest of the dam, and added armoring to allow the crest to function as a spillway. This work greatly increased the capacity of the dam to accommodate increased spring runoff and intense summer thunderstorms.