How to repair a deteriorating, 90-year-old dam in the Alpine Lakes Wilderness near Leavenworth is the subject of a draft environmental impact statement released today by the Washington Department of Ecology.
The Eightmile Lake Dam is one of several small dams located in the Cascade Mountains west of Leavenworth, predating the establishment of the Alpine Lakes Wilderness by several decades. Eightmile Dam provides water for agricultural irrigation and instream flows during the dry summer months.
After the Jack Creek Fire in 2017, flooding caused erosion damage to the dam. In 2018, the Eightmile Lake Dam was designated as a high hazard dam by Ecology’s Dam Safety Office, reflecting its potential threat to downstream residents and properties. Emergency repairs made in the summer of 2018 stabilized the dam. However, these repairs did not bring the dam up to current safety standards.
As the dam’s owners, the Icicle and Peshastin Irrigation Districts (IPID) have developed several alternatives for rebuilding the dam, which balance the priorities of protecting the integrity of the Alpine Lakes Wilderness, ensuring public safety by meeting dam safety requirements, and providing durable solutions for water management and delivery. The alternatives also account for the likely impacts of climate change on severe weather events, irrigation needs, and fish habitat.
IPID is considering three action alternatives for rebuilding the dam and a status quo, “no action” alternative:
- Alternative 1: Narrow spillway with gates. This has a smaller footprint than Alternative 2 and has more potential water storage than Alternative 3. The gates would protect the dam from overtopping.
- Alternative 2: Wide spillway without gates. This has the largest footprint of the alternatives.
- Alternative 3: Narrow spillway without gates. This has the lowest potential water storage of the alternatives.
- No Action Alternative: Operating the current dam with no changes.
The Draft EIS examines the probable, significant, and adverse impacts resulting from each course of action It also analyzes how impacts can be reduced or eliminated through mitigation.
An EIS is an impartial, comprehensive study used as a resource for decision-makers and the public. An actual repair plan, and the associated permit decisions for that work, will be made after completion of the EIS. The Final EIS is expected to be issued this fall.
How to participate
Ecology is accepting comments on the Draft EIS through June 5, 2023. Submit comments through our online form at ecology.wa.gov/eightmile or in writing to Washington Department of Ecology, Attn: Eightmile Draft EIS, 1250 W. Alder Street, Union Gap, WA 98903.
The public can learn more about the project, ask questions, and make verbal comments during three scheduled hearings (two online, May 1 and May 16, and one in person, May 11). Identical information will be shared at each meeting.
Join online for a virtual public meeting
- May 11, Chelan County Fire District #3, 228 Chumstick Hwy, Leavenworth
- The presentation will start at 6:30 p.m.
- Registration link
Review the Draft EIS
- Online at ecology.wa.gov/eightmile.
- At the Leavenworth Public Library, 700 US Hwy 2, Leavenworth.
- At Department of Ecology, Central Region Office, 1250 W. Alder St., Union Gap. Call 509-575-2490 for an appointment.
- At Department of Ecology, Northwest Region Office, 15700 Dayton Ave. N., Shoreline WA 98133. Call 206-594-0000 for an appointment.
Ecology will consider comments received during the comment period when finalizing the EIS later this year. More information about the meetings and the project documents are at ecology.wa.gov/eightmile.