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~ . ' [River mile designations were taken from Evans and Belknap's Dinosaur River guide (+120 miles), Evans and Belknap's Desolation River Guide (+120 miles), and Belknap and Belknap's Canyonlands River Guide] Seven flows [cubic feet per second (cfs)] were examined for backwaters at the Island Park, Jensen, Ouray, and Sand Wash sites: 5,260, 2,423, 1,773, 1,687, 1,430, 1,381, and 1,101. Three flows were examined at the Mineral Bottom site: 3,814, 3,261, and 2,748. Flows for the four upper sites were measured at the Jensen gauge, and the Mineral Bottom flows were measured at the Green River gauge. When flows were stabilized at each site, color infrared aerial photography was acquired at an approximate scale of 1:4000. Flows were gradually stepped down during the late spring and summer in order to mimic the descending limb of a "natural" Green River hydrograph. However, because of weather conditions the 1,430 flow was not photographed in proper sequence and was actually the last flow attained. Field trips were taken to familiarize the photointerpreter with backwater delineation and to place panel markers at specified distances at each site to verify photographic scale. In addition, one to three reference backwaters were selected at each flow for the Island Park, Jensen, and Ouray sites, and three reference backwaters were selected at three flows at the Sand Wash site. Reference backwaters were measured for length and width, and three depth measurements were taken at the mouth, mid, and end points of each. Aerial photographs were fitted with mylar overlays and interpreted for the following classes: - Riparian Vegetation - Open Water - Vegetated Islands - Vegetated Sandbars - Sandbars - Bank - Backwaters - Channel - Backwaters - Isolated Pools Because the aerial photography was at a relatively large scale (1:4000), it would have been difficult to transfer the interpreted classes to a standard 1:24,000 scale U.S. Geologic Survey (USGS) quad, as the integrity of the larger scale data base would be lost. Therefore, to maintain interpretation accuracy, pseudomap bases of the same scale as the photography were created. Roads and other prominent features were delineated on photographs and compared to USGS maps to insure photo scale accuracy. Following transfer of photointerpretation data to pseudomap overlays, the information was digitized into a GIS system utilizing Geographic Entry System software. Digitization was done in vector format using a Calcomp 9000 digitizing tablet linked to a Tektronix 4014 display screen. Software and peripherals were run by the HP 3000 Series III computer. Each study site was approximately 7.5 by 7.5 minutes, making the internal resolution of the computer 0.7 feet. The digitizing procedure was well within the potointerpretation error limits. Map plots and tabular summaries were produced for each site.