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. . Flow data Annual discharge data for the lower Duchesne River were taken from U.S. Geological Survey annual water-data reports for each of the water years of this study. This flow data was taken from the Randlett stream gage located below the confluence of the Uintah River near river- mile 14. Total discharge, peak (maximum-daily), and daily mean discharge were used in our analysis to describe flow regimes. . . Analysis Correlation coefficients (Pearson r) were calculated to assess the degree of association among years between annual discharge parameters and annual relative abundance of fishes in the lower Duchesne River below Myton. The objective ofthis analysis was to estimate the degree of association between discharge parameters and relative abundance and not to describe the functional relationship. The significance level for coefficients was set at P ~ 0.10. Coefficients ofr 2:: 0.88 were considered statistically significant. Degree of association for correlations with non-significant coefficients was considered strong for r values of 0.78-0.87. . Results and Discussion . Flow Regimes Annual flow regimes of the lower Duchesne River over the three years of this study were generally moderate with some variation in timing and duration of peak flows and magnitude of sustained summer base flows. There were not any unusually high or low flow years. The peak flow of 1997 was the earliest and lowest of the three years, with a peak of 4120 cfs (50 % exceedence; period of record 1943 - 1999) on 3 June. Flows in 1998 peaked near 5880 cfs (28 % exceedence) on 18 June and had the longest duration of the three years. Summer base flows stayed above 500 cfs during 1998. Peak flows in 1999 were of shorter duration and higher magnitude than the preceding two years of the study (Figure 2). Flows peaked near 7000 cfs (18 % exceedence) on 20 June 1999, then dropped off to less than 1000 cfs by 2 July and reached the summer=s lowest flows (daily mean of 193 cfs) on 14 July. The Duchesne River channel was reshaped and redirected in some areas by high flows of 1999. Many areas experienced substantial bank erosion and shifts in the channel location. In one instance the channel near river-mile 28.0 (Peacock Farm) cut through a bend in the channel uprooting cottonwood trees and washing old agricultural equipment and junk automobiles into the river . . . . 5 .