Based on recent water supply forecasts for the Kootenai River Basin, an experimental spill at the Libby Dam is scheduled for late May or early June to test whether increased flows into the river will benefit white sturgeon.
Due to low snowpack, there was speculation coming out of winter whether there would be sufficient water to conduct the spill, which had been given the green light – if certain conditions were met – following a 2008 legal settlement. That settlement, which named six entities, clarified portions of a 2006 U.S. Fish and Wildlife Service biological opinion and called for a habitat restoration plan for white sturgeon.
Montana state officials had long resisted a test spill at Libby Dam, arguing that it would create gas levels in the Kootenai River higher than allowed by state standards and could potentially harm native fish downstream of the dam.
The decision to conduct the spill is based off a May water supply forecast by U.S. Army Corps of Engineers, which operates the Libby Dam. Spring precipitation has boosted water supply after a winter of low snowpack.
According to the Corps of Engineers, Libby Dam is capable of passing approximately 25,000 cubic feet per second of water through its turbines. Additional flows of up to 10,000 cubic feet per second for up to seven days could be spilled during the test. Libby Dam was built on the Kootenai River in 1974 and forms Lake Koocanusa.
The spill is designed to test whether additional flows will benefit white sturgeon, which have had low egg survival rates during spawning in the riverbeds downstream of Bonners Ferry, Idaho. Officials want to see if the spill encourages sturgeon to move upstream of Bonners Ferry into better spawning habitat.
The groups named in the 2008 settlement were Bonneville Power Administration, the Center for Biological Diversity, the Corps of Engineers, the state of Montana, the U.S. Fish and Wildlife Service and the Kootenai Tribe of Idaho.
Related: Landmark Settlement Gives White Sturgeon a Glimmer of Hope