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I I I I I I I I I I I I I I I I I I I 5 In a previous report (Van Steeter and Pitlick, 1994), we summarized similar results, but used photographs from 1986 since the 1993 set was not yet analyzed. This report focuses on results from this updated analysis as well as results for Ruby-Horsethief Canyon. Results Results for the Grand Valley showed that there was a substantial decrease in the area of channel features when comparing 1937 to 1993 and 1954 to 1968. The 1937-1993 analysis of the Grand Valley shows that there was a 19% decrease in water area, 12% decrease in island area, and a 26% decrease in side channel/backwater area (Fig. 3, Table 1). The 1954-1968 analysis showed a 12% decrease in water area, a 18% decrease in island area, and a 29% decrease in side channel/backwater area. See Van Steeter and Pitlick (1994) for more detail. Examples of channel change are illustrated in Figures 4 and 5. Results of the analysis of Ruby-Horsethief Canyon for 1937-1993 show a decrease of 6.5% for water area, a 9.5% increase in island area, and a 23.2% decrease in side channel/backwater area (Fig. 6, Table 2). For 1954-1968 there was a 3.4% decrease in water area, a 4.2% increase in island area, and a 2.4% decrease in side channel/backwater area (Fig. 7, Table 3). Mile by mile maps of channel change are located in Appendix I and II. Although it is somewhat useful to compare the two reaches by percent change, it is important to note that the area of channel features in the two reaches are very different. The Grand Valley reach has significantly larger water, island, and side channel/backwater areas than Ruby-Horsethief Canyon. When the average area of each channel feature per mile is calculated for the two reaches, it shows that water area is 21 % greater in the Grand Valley, island area is 280% greater, and side channel/backwater area is 175% greater than in Ruby-Horsethief Canyon.