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During moderate flow periods and in the absence of high scouring flows, sediment deposits were quickly stabilized by vegetation (including introduced tamarisk) and natural levees developed (Graf 1978, 1985). Flooding frequency temporarily increased as even moderate flows filled narrowed, vegetation-encroached river margins. Sediment was deposited in low velocity vegetated surfaces on top of river bank margins and mid-channel islands, raising surface elevations from 1 m to 3.5 m above low water level in the Canyonlands reach of the Green River. -River widths in this reach were reduced on average 27 percent with a range of 13-55 percent (Graf 1978). Continued water depletions coupled with increased bank height eventually reduced overbank flooding frequency. Agricultural and urban development along rivers resulted in additional levee construction compounding the effects of natural levee formation. Dam construction in the 1960s further reduced seasonal flow variability and led to further reduction in floodplain connectivity. Mitigation projects for loss of floodplain resulted in wetland projects such as Ouray National Wildlife Refuge on the middle Green River. These projects resorted to construction of levees (Figure 8) and expensive diversion and pumping facilities to route water into wetland areas for waterfowl production. Unfortunately this approach was initiated prior to thorough examination of historic waterfowl production numbers and consideration of alternative management options more in tune with natural flow patterns required by native vegetation and wildlife. These projects often became multi- purpose and included agricultural components and hunting enhancement. On the middle Green River after the closing of Flaming Gorge Dam, access to productive low velocity habitat for native fishes became a rare 10-year event instead of a regular occurrence about once every 2 or 3 years. Loss of floodplain connectivity occurred throughout the entire upper basin due to reduction in peak flows, except during extremely high flow years that occurred in the mid 1980s (Figure 9). 18