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Ecology

Assessment of the Impacts of Development and Operation of the Columbia River Hydroelectric System On Mainstem Riverine Processes and Salmon Habitats

Salmon habitats in the Columbia and Snake rivers have changed dramatically during the past 60 years because of hydroelectric development and operation. For example, much of the former riverine environĀ¬ment where salmon spawned is now a series of low-velocity impoundments. Hydroelectric dams have also created impassable barriers that block access of salmon and steelhead to many historic habitats. Changes in water quality, temperature, food supply, and flow regimes have also affected salmon survival and behavior. The overall effect of these changes to freshwater aquatic ecosystems has been a reduction in the production capacity of the Columbia River for anadromous salmonids.

This project consisted of three separate, but closely related, studies designed to address overall goals of this project, which were to: 1) identify the amount of mainstem river salmon spawning and juvenile rearing habitat lost to development and operations of the Columbia River hydroelectric system, 2) identify the types of ecological modifications that have occurred, and 3) suggest areas or actions with particular potential for restoration of riverine habitat. The first study was a quantitative assessment of salmon and steelhead habitats lost because of hydroelectric development. The second effort was a workshop focused on developing a list of restoration options, including risks and benefits of implementing those options, for mainstem habitats in the Columbia and Snake rivers. The final study provided a test of two restoration strategies: 1) drawdown of John Day reservoir on the lower Columbia River, and 2) removal of the four lower Snake River dams. Collectively, the results of these studies represent sigĀ¬nificant progress toward defining locations in the Columbia and Snake rivers with greatest potential for restoration of mainstem riverine processes and salmon habitats.

Products:

  • Dauble, D. D., T. P. Hanrahan, D. R. Geist, and M. J. Parsley. 2003. Impacts of the Columbia River hydroelectric system on main-stem habitats of fall chinook salmon. North American Journal of Fisheries Management 23: 641-659.
  • Battelle and U. S. Geological Survey, 2000. Assessment of the impacts of development and operation of the Columbia River hydroelectric system on mainstem riverine processes and salmon habitats. Final report to the Bonneville Power Administration, Division of Fish and Wildlife, Portland, OR.

Ecology

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