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) 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) was prepared under the State Environmental Policy Act (SEPA), to examine the potential environmental consequences of each proposed alternative to rebuild the dam. The Final EIS was issued on June 21, 2024. Construction of a wide spillway without gates (Alternative 2) was chosen as the preferred alternative.

With the completion of the EIS, Icicle and Peshastin Irrigation Districts (IPID) will now begin engineering design, followed by permitting and eventually construction of the new dam.

Overview and recent events

Eightmile Lake is one of four lakes within the boundary of Alpine Lakes Wilderness Area managed by 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) released a draft EIS for Eightmile Dam for public comment on April 19, 2023. OCR considered the comments, made appropriate changes, and issued the Final EIS on June, 21, 2024. The 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, were also evaluated.

Four alternatives for replacing the dam were considered in the EIS. Alternative 2, construction of a dam with a wide spillway without gates, was chosen as the preferred alternative.

Alternatives and supporting documents 

Frequently Asked Questions