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Bull noted that most fluvial systems usually respond to several changes in several independent variables, each having its own time lag associated with attainment of a new equilibrium condition. Thus, evaluating the equilibrium status of a reach of river involves measurement of channel changes and consideration of the status of the independent variables: climate, man-caused changes, and flood history. In discussing the processes that influence channel shape and form, Wolman and Miller (1960) re-examined the concept of "effective force" to provide a measure of the level at which the largest portion of total work is accomplished. For a river, the largest portion of total work is associated with a discharge where the product of frequency of occurrence and rate of sediment transport is maximized. This maximum relates to a relatively frequent discharge, occurring on the average once or twice a year for the data reviewed by these authors. From a morphologic standpoint, Wolman and Miller demonstrate that the bankf ll discharge should be the most "effective" discharge controlling the development of the floodplain and the channel shape. On the average, the bankfull discharge is attained every 1 to 2 years, controlling the channel shape and floodplain with a force of moderate magnitude which recurs relatively frequently. According to Wobnan and Miller, regional analysis is necessary to fully evaluate the effect of various geomorphic processes on landform shape. Discharges of unusual magnitude are more influential in situations where stresses associated with frequent events are incompetent to transport the available materials. Also, precipitation, temperature, and vegetation interact with erosion to determine sediment availability in a watershed. The objective of this study is to describe the Green River sediment transport and channel width characteristics during the post-reservoir period from 1965 to 1987. Andrews' 1986 data will be supplemented by: • using a more extensive channel length to monitor channel width changes • focusing on the portion of the suspended sediment load that represents the majority of particle sizes found in the bed material in this portion of the Green River METHODS The impact of Flaming Gorge Dam upon channel morphology and sediment transport of the Green River was quantified in our study using comparative analysis of aerial photography and GIS (Geographical Information Systems) techniques, published gauge records for U.S. Geological Survey gauges, and analysis and interpretation of sediment data collected from 1986 to 1988. The stability of the channel is of interest because progressive channel changes may adversely impact the habitat conditions required by endangered species endemic to the Green River (Tyus and Karp, 1989). 3