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Channel Geomorphology Changes in channel geomorphology produced by normal and augmented streamflows were determined from (i) analysis of aerial photographs taken seven years apart and (ii) repeated surveys of channel cross sections in selected reaches. Aerial Photographs: High quality color aerial photographs of the critical reaches of the Colorado River were taken in August, 2000, for the purposes of comparison with an earlier set of photographs taken in September, 1993. The separate sets of photographs cover the same section of the Colorado River from Palisade to approximately Loma, CO (RKM 300-250), and they were flown at the same scale (1: 6000), in late summer, with the river flowing at approximately the same discharge. Both sets of photographs were georeferenced by Positive Systems, resulting in seventeen total georeferenced mosaics. Eight mosaics from the 1993 data set and 9 mosaics from the 2000 data set were used to delineate channel characteristics. The aerial photographs were not orthorectified to account for flight angle or distortion effects; however, these effects were assumed to be minimal given the relatively low relief of the river and surrounding terrain in the study area. Georeferencing was done in UTM coordinates. From the aerial photographs, a layer in ArcView was digitized to represent the boundary between river miles. The layer created in ArcView for these river miles stores the UTM coordinates from the mosaic of aerial photographs, thus allowing a single layer for river miles to be utilized on the aerial photographs from both years. This assures the comparison between years will be based on identical sections of channel. These river mile boundaries were verified between topographic maps and the aerial photos. For each year, in each river mile, a separate layer was digitized to represent the main channel, side channels, and exposed channel bars. Thus each river mile for each year contains 12