February 13, 2020
Dam designs for Eightmile Lake pose questions about how much the level of the lake could go up – or down.
The Up question centers on what was the historic level that the Icicle-Peshastin Irrigation District now promises not to exceed, and whether it has a right to raise the dam that high. All the dam designs under review would raise the lake higher than it is now.
The Down question stems from the irrigation district's proposal to extend its siphon pipe farther out into deep water. This would allow it to suck out colder water that it claims would benefit downstream fish, but it also would allow the irrigation district to draw out more total water and lower the lake level even more. It claims it would do this only in "drought" years.
Both questions will likely be debated in an upcoming environmental review that is about to start. The state Department of Ecology is selecting consultants to undertake an environmental impact process under the State Environmental Protection Act (SEPA). This will discuss what appear to be three alternative dam designs and their likely effect. If the prior SEPA process on the Icicle's programmatic review is any indication, this new effort will not attempt to resolve questions about the extent of the irrigation district's water rights or what is allowed within the Alpine Lakes Wilderness.
The easement granted by the Forest Service to the irrigation district when it bought the Eightmile Lake property allows the irrigation district to regulate the lake level. But the Forest Service says that this does not allow any change above or below historic levels. It also says the easement does not cover the subject of where a siphon pipe can be located. Both, per the Forest Service, would require a special use permit. That, in turn, would trigger a federal environmental review process.
The dam design alternatives are shown at: https://www.co.chelan.wa.us/files/natural-resources/documents/Planning/icicle_work_group/current-project/Eightmile%20Lake/Eightmile%20Lake%2030%25%20Design%20Drawings_2019.pdf