Open-File Report 2011–1268
Prior to operational changes in 2007, Detroit Dam on the North Santiam River in western Oregon had a well-documented effect on downstream water temperature that was problematic for endangered salmonid fish species. In this U.S. Geological Survey study, done in cooperation with the U.S. Army Corps of Engineers, an existing calibrated CE-QUAL-W2 model of Detroit Lake (the impounded waterbody behind Detroit Dam) was used to determine how changes in dam operation or changes to the structural release points of Detroit Dam might affect downstream water temperatures under a range of historical hydrologic and meteorological conditions.
Many combinations of environmental, operational, and structural options were explored with the model. Two downstream temperature targets were used along with three sets of environmental forcing conditions representing normal, hot/dry, and cool/wet conditions. Three structural options were modeled, including the use of existing outlets, one hypothetical variable-elevation outlet such as a sliding gate, and a hypothetical combination of a floating outlet and a fixed-elevation outlet. Finally, four sets of operational guidelines were explored to gain an understanding of the effects of imposing different downstream minimum streamflows or managing the level of the lake with different timelines in autumn.
Several conclusions can be made from these interim model scenarios:
This report provides interim study results to the U.S. Army Corps of Engineers. The full study will be completed in 2012.
First posted October 4, 2011
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Buccola, N.L., and Rounds, S.A., 2011, Simulating potential structural and operational changes for Detroit Dam on the North Santiam River, Oregon—Interim Results: U.S. Geological Survey Open-File Report 2011–1268, 32 p.
Purpose and Scope
Discussion and Conclusions