Spill planned to promote white sturgeon spawning

Federal agencies are coordinating with the state of Montana and Kootenai Tribe of Idaho to spill extra water at Libby Dam in the spring to promote spawning of the endangered Kootenai River white sturgeon.

This spring spill operation is dependent upon the water supply in Lake Koocanusa north of Libby, as well as other conditions.

The operation is part of an effort to encourage sturgeon migration in the Kootenai River upstream from Bonners Ferry into suitable spawning habitat in a cobble and gravel-bottomed stretch of the river.

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.

The efforts follow a determination by the U.S. Fish and Wildlife Service that 2008 and 2009 operations did not help the protected sturgeon as much as a team of regional biologists had anticipated.

The Wildlife Service evaluated the effects of dam operations according to criteria set forth in a settlement agreement to the agency’s 2006 Biological Opinion, which outlines required protections for sturgeon affected by Libby Dam, and considers indicators of recovery such as sturgeon migration and spawning.

A key requirement is for the Corps, which operates Libby Dam, and Bonneville Power Authority, which markets its hydropower to provide river flows, depths, temperatures and gravels that encourage sturgeon to swim upriver for spawning.

The Wildlife Service’s determination that dam operations did not meet the criteria for sturgeon two years in a row means that additional water will be released over the Libby Dam spillway for up to one week during late spring from 2010 through 2012. Biologists will evaluate the effects of the extra water on sturgeon migration and spawning.

The spills will occur sometime between late May and late June, depending on water supply forecast, runoff projections, water temperature and reservoir elevation.

The Army Corps of Engineers will hold its annual public meeting in April or May to provide more detail on the 2010 operational plan, and federal, state and tribal representatives will also be present.

“The Corps’ primary consideration is minimizing risk to human life, health and safety, while meeting Libby Dam’s multiple purposes and responsibilities,” said Libby Dam Operations Manager Mick Shea. “The spill operation will be closely monitored to ensure that the spill test does not exceed flood stage below Libby Dam.”