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. water years 1944-46 and also approximately between water years 1963-65 (fig. 4). Cumulative annual stream discharge versus time was plotted (not presented) to help identify changes in stream-discharge trends that might have occurred; however. no long-term changes in annual stream discharge were evident, but variability of annual mean discharges is significantly smaller during 1964-82 than during 1930-63. CUmulative annual sus~nded-sediment load versus time was plotted in figure 5 to help identify changes in suspended- sediment trends that might have occurred. and changes in slo~ similar to the changes in the double-mass curve (fig. 4) are app:lrent. '!bus, sane factor (s) other than annual stream discharge also influenced the change in trend of sus~nded sediment. The change that occurred between water years 1944-46 coincides with a change in sampling equipment. '!be u.s. Ir43 sus~nded-sediment sampler was first used at station 09315000 during October 1945 (1946 water year). The change that occurred approximately between water years 1963-65 coincides with the completion of Flaming Gorge Dam during November 1962 (1963 water year), which impounds water contributed from about 43 percent of the drainage basin upstream from station 09315000. Flaming Gorge Reservoir acts as a sediment trap, and it removes most of the sus~nded sediment in the Green River from all sources upstream from the dam. Although little change in annual streamflow occurred after the reservoir was essentially full, the distribution of streamflow did change. A comJ;8rison of, flow-duration curves (fig. 6) for 1930-62 and 1965-82 (1963-64 was not used because the reservoir was filling) shows that the reservoir reduced peak flows and increased minimum flows. This change in the distribution of streamflow undoubtedly affected susp:mded-sediment loads. A double-mass curve (similiar to figure 4) also was constructed (not presented) for station 09261000, the Green River near Jensen, which is 202.5 river miles upstream from station 09315000 and 87 river miles downstream fran Flaming Gorge Dam. Continuous annual data for water years 1949-79 were plotted. A change in slo~ was noted approximately between water years 1963- 65, similar to the change in figure 4. This second plot helps confirm that Flaming Gorge Reservoir influenced the change in the relationship between annual sus~nded-sediment loads and annual streamflow in the Green River at station 09315000. e e Mean annual loads were reduced by about 50 percent at station 09261000 and by about 35 ~rcent at station 09315000 after the closure of Flaming Gorge D3m (table 1). ~e reduction in annual sus~nded-sediment yield of the Gr~ River downstream from Flaming Gorge Dam is about 110 tons per square mile. Other factors may have been involved or responsible for the changes that occurred between water years 1944-46 and 1$3-65, but their identification is beyond the scope of this report. It is most probable, however, that the changes in relationship that occurred at station 09315000 were caused by changes in sampling equipment in October 1945 and the completion of Flaming Gorge Dam in November 1962. e 9