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Draft Final Completion Report to UDWR for Contract #93-1070. Amendment 3 ill River near Ouray also must consider the fact that the majority of flood flow characteristics are determined by the natural variability of the unregulated Yamoa River. The role of Aaming Gorge Dam could be to (I) augment the magnitude of ~ -,~-~-~ the annual flood in all or some years. (2) extend the duration of the annual flood in all or some years, and/or (3) control the magnitude of summer. fall. and winter base flows. Results from this research project suggest that the first and third options are most appropriate. Methods A multi-scale approach was used in which swveys of monumented cross-sections and detailed bar topography were made within a 1.5 kIn study reach (the l.5-km reach) between 1992 and 1994. Detailed measurements were made at one bank-attached compound bar (the detailed study site) within this reach. An existing three-dimensional flow and sediment transport numerical model (Andrews and Nelson. 1989) was modified and applied to the l.5-kIn reach. and these field and modeling data were used to characterize river response to the passage of the annual snowmelt flood. Field measurements of surface flow patterns, habitat measurements made by the Utah Division of Wildlife Resources. and analysis of video and air photo imagery of a lO-kIn reach (the lO-km reach) were used to evaluate the development and transformation of nursery habitats over several years. Trends within the 10-kIn reach were compared with those in the l.5-kIn reach in order to evaluate the validity of extrapolating results obtained at detailed scales to the larger reach scale. Results and Conclusions The channel of the Green River near Ouray has a sand bed. The channel meanders with a relatively long wavelength of about 1.6 kIn. and the meander belt is restricted because the channel intermittently encounters bedrock at the outside of bends. At low flow. the channel meanders with a shorter wavelength between emergent bank-attached compound bars and stabilized channel banks. Nursery habitat occurs as areas of stagnant flow on the upstream and downstream sides of the emergent bars. and along emergent bar margins behind superimposed bars and in inactive chute channels. The size and shape of these bars changes from year to year. and so does the distribution and size of nursery habitats. Field measurements and modeling predictions confirm the earlier findings of Andrews and Nelson (1986) that the Green River-channel near Ouray is dynamic and quickly adjusts to changing discharge. The thalweg scours, and