Eightmile Dam rebuild & restoration

Backhoe moving rocks, lake in background, rock dam wall at left

Emergency temporary construction at Eightmile Dam

In 2018, the 90-year-old Eightmile Lake Dam in the Icicle Creek watershed was designated a high hazard and a threat to downstream residents and properties. A state of emergency was declared in the watershed, after flood damage and erosion at the dam caused by impacts of the Jack Creek Fire in 2017. Emergency repairs made in the summer of 2018 stabilized the dam, but these repairs do not meet current dam safety standards.

The Icicle and Peshastin Irrigation Districts (IPID) has worked with our Dam Safety Office to develop options to restore and rebuild the dam to meet current safety standards. An environmental impact statement (EIS) is being prepared under the State Environmental Policy Act (SEPA), to examine the potential environmental consequences of each proposed alternative to rebuild the dam. We accepted comments on the scope of the EIS, ending Feb. 1, 2021, and took that feedback into consideration when preparing the draft EIS.

Overview and recent events

Eightmile Lake is one of four lakes within the boundary of Alpine Lakes Wilderness Area managed by Icicle and Peshastin Irrigation Districts (IPID). A small dam, low-level outlet pipeline, and slide gate at the outlet of Eightmile Lake allow for controlled releases of stored water to supplement flows in Icicle Creek and provide irrigation during low flow periods, typically during late summer.

Icicle Creek also supports the domestic water supply for the city of Leavenworth, hatchery fish raised at the Leavenworth National Fish Hatchery, streamflows and natural aquatic habitat for wild fish, and recreation.

Floodwaters overtop an earthen and rockwall dam

In the spring of 2018, floodwaters and runoff overtopped Eightmile Dam.

The 2017 Jack Creek Fire in the Alpine Lakes Wilderness burned several hundred acres in the Eightmile drainage. In spring of 2018, increased runoff filled the dam so much that water began flowing over the earthen portion of the dam resulting in an emergency declaration and temporary repairs at the dam. Reconstructing the aging dam structure at Eightmile Lake is crucial to protecting downstream residents, the natural shorelines and habitats of Icicle Creek near Leavenworth in Chelan County, and the water use of area irrigators.

As a result of these events, Ecology’s Dam Safety Office (DSO) evaluated the dam and designated it as a high hazard for failure and a threat to people and property downstream. DSO regulates dams in Washington and through the administration of state laws and rules ensures that safety is the priority to protect people and property located downstream of dams.

Environmental Impact Statement

Ecology’s Office of Columbia River (OCR) is expediting the completion of an EIS for Eightmile Dam. OCR submitted a draft EIS for public comment on April 19, 2023. The Draft EIS is  an environmental review of potential impacts. These topics include water rights, water availability, water quality, historic and current water and dam elevations, fish type and use in the lake and streams, economics evaluations, construction methods, cultural resources, recreation, visual resources, and geologic hazards. Consistency with applicable federal laws, including the Wilderness Act, will also be evaluated.

Alternatives and supporting documents 

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