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Green River Upper and Lower Monitoring Reaches - 1989 The upper monitoring reach of the Green River was generally wider (table 3) and had substantially more backwater and side channel numbers and area than the lower reach (tables 1,2). Backwater number/mile in the upper reach was greatest from river-miles 236 to 295, while backwater area/mile was greatest from river-miles 236 to 275 (table 1). In the lower reach, backwater/mile was fairly consistent, but backwater area/mile was substantially greater for river miles 16-75 than other segments. River-miles 0 to 15 and 76 to 95 had the least backwater number and area/mile, and this trend was also reported for 1988 (Pucherelli and Clark, 1989). The upper reach was flown on 2 consecutive days and consequently, two different flows were video taped. Flow at the Jensen gauge increased from 1,023 to 1,236 fe /s on September 27 and increased again to 1,420 fe /s on September 28. Video taping was started at about the Ouray bridge on September 28 and, therefore, backwater number and area above this point may have been slightly effected, and were probably decreased somewhat from the previous day, if trends from previous studies are consistent (Pucherelli and Clark 1989). Channel width measurements are not effected by flow, as the bank full width is measured regardless of flow. Side channel number and area/mile were about 80 percent less for the lower reach than the upper reach (table 2). The upper reach is generally more braided with more islands and associated sand bars. Colorado River Upper and Lower Monitoring Reaches - 1989 The upper reach of the Colorado River is generally wider than the lower reach (table 6), with substantially more backwaters (table 4) and side channels (table 5). Although the lower reach had fewer and smaller backwaters (table 4), some segments had more backwater number and area/mile than others (river-miles 0 to 20, 41 to 60, and 101 to 110). Side channel area/mile was about 80 percent greater for the upper reach than the lower (table 5). Green River 1988-1989 Backwater Comparisons The Green River was video taped from its confluence with the Colorado to its confluence with the Yampa, in September 1988 to acquire low-flow baseline backwater information (Pucherelli and Clark, 1989). The lower and upper monitoring reaches were extracted from the 1988 data and compared with the 1989 backwater data in table 7. Flows at the GS Jensen gauge were slightly higher when the 1988 photography was acquired than for the 1989 (see flow table in methods) video dates, and this may effect any comparisons between the 2 years. However, we feel the flows were close enough to make some general observations. There were substantially fewer backwaters recorded in 1989 for both reaches, but backwaters were larger in 1989 than 1988. Backwater number was reduced by 44 percent from 1988 to 1989, from 208 to 116 in the lower reach, but backwater area increased 12 percent from 60,924 to 68,457 m2. The average size of a backwater more than doubled, increasing from 293 to 590 m2. This may be a function of the low flows that occurred during 1989. In the upper reach, backwater number decreased by 34 percent in 1989 from 567 to 376. Backwater area increased 16 percent from 212,893 to 247,635 m2 and the average backwater size increased from 375 to 659 m2. Figures 2 and 3 represent a video image of river-mile 254 (Ouray site) from 7