Federal agencies continue to coordinate on spring spill at Libby Dam
by U.S. Army Corps of Engineers – Libby Dam
March 25, 2010
The State of Montana Department of Environmental Quality issued a temporary waiver of the state’s water quality standard for total dissolved gas on the Kootenai River this week in coordination with Federal agencies and in consultation with the Kootenai Tribe of Idaho, to allow the Corps to potentially spill water for a week this spring at Libby Dam. In the waiver Montana included conditions on the spill operation because of concerns related to water quality and the protection of other fish below Libby Dam
The spring spill operation is dependent upon the water supply forecast and reservoir elevation of Lake Koocanusa, as well as other conditions, and is intended to test whether additional flows may meet habitat attributes required in the Biological Opinion for the endangered Kootenai River white sturgeon.
The power house at Libby Dam is capable of passing 25,000 cubic feet per second of water. Additional flows of up to 10,000 cubic feet per second could be spilled during the seven day operation. If sufficient runoff is available, the spills will occur sometime between late May and late June, depending on water supply forecast, runoff projections, water temperature and reservoir elevation.
The U.S. Army Corps of Engineers' primary consideration in operating Libby Dam is minimizing risk to human life, health and safety, while meeting the project’s multiple purposes and responsibilities. The spill operation will be closely monitored to ensure that the spill test does not exceed flood stage below Libby Dam.
The current water supply forecast indicates that we’re already experiencing a low water year, and the overall volume of precipitation appears likely to further decline. Under the current U.S. Fish and Wildlife Service Biological Opinion, Libby Dam’s annual sturgeon operations are determined by the final May water supply forecast for April – August 2010, received typically on the fifth working day of May. If spill does not occur this year, sturgeon operations for 2010 will focus upon temperature management.
This spill operation is part of a collaborative, on-going effort to encourage migration of endangered white sturgeon into habitat in the Kootenai River upstream from Bonners Ferry, Idaho. The biologists’ ultimate intent is to achieve appropriate river conditions that foster sturgeon spawning, successful egg hatching, and survival of larval fish. While hatchery reproduction has increased the number of young sturgeon in the river, federal, state, and tribal partners hope to improve habitat conditions for adult sturgeon to successfully reproduce on their own in the river through habitat restoration in the existing spawning area downstream of Bonners Ferry, Idaho, as well as upstream, with the spill test and other actions.
The Corps will hold its annual public meetings in Bonners Ferry, Idaho, on May 17, and in Libby, Mont., on May 20, to provide more details Libby Dam operations for 2010. Federal, state and tribal representatives will also be present.
Kootenai River white sturgeon were listed as an endangered species in 1994. They have not produced a significant number of offspring in the wild since 1974. Flood control and hydropower operations have altered the sturgeon’s habitat, affecting reproduction.
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