Kootenai River nutrient enhancement project
July 25, 2005
Fishery officials have begun a project of pumping liquid phosphorous and nitrogen into the Kootenai River at the Montana/Idaho border with the hope of rebuilding a depleted ecosystem and boost native cutthroat and rainbow trout and whitefish populations.
According to a story on the project in the Columbia River Bulletin, Fish & Wildlife News, the infusion of nutrients could boost growth and populations of white sturgeon, burbot, bull trout and kokanee. The five-year project involves channeling the liquid phosphorous and nitrogen into the river from about late June through September in an effort to improve fisheries habitat.
The Kootenai River is the second largest tributary to the Columbia River system. Fisheries biologists will be specifically treating the stretch of the Kootenai from the Montana/Idaho state line to Bonners Ferry, Idaho. This is an "autotrophic" zone where sunshine penetrates to the bottom of the river. Biologists hope sunshine, along with the introduced phosphorous and nitrogen, will kindle the growth of algae on rocks in this portion of the river and stimulate production of aquatic insects and invertebrates, providing food for fish. Normally, naturally occurring nitrogen and phosphorous fuel that growth.
With the completion of Libby Dam in 1972, most of the nutrients that had been annually flushed down the river were effectively trapped in the reservoir. Biologists feel nutrients are being lost behind Libby Dam and hope the project will bring fish productivity up to a level that would have existed prior to building the dam. What nutrients that do escape are generally utilized in river stretches immediately below the dam. By the time the river gets to the Bonners Ferry area, the nutrient level is extremely minimal.
The U.S. Army Corps of Engineers, which operates Libby Dam, was involved in the planning of the nutrient project. The Kootenai Tribe of Idaho and the Idaho Department of Fish and Game are leading the project and will be monitoring and evaluating the effects of the nutrient additions to determine if the project should continue permanently. The nutrients will quickly be diluted by the river water and will not present any danger to either fish and wildlife or people using the river for recreation.
Related Links:
The Columbia River Bulletin Fish & Wildlife News, Friday, July 22, 2005
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