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A III computer. Each study site was approximately 7.5 by 7.5 minutes, making the internal resolution of the software 0.7 feet. ~hus, the digitizing procedure was well within the \P~Poeointerpretation limits associated with 1:4,000 scale aerial photography. Photo interpretation is somewhat subjective and it's accuracy is difficult to quantify. Precise and consistent decisions by the photo interpreter minimize error in the process. Tabular summaries were produced for each site and map plots were generated for specific sites. For the purposes of this study, a backwater was defined as an inlet or inundated portion of a sandbar or cobblebar where there was no water velocity. Backwaters may occur at the upstream, downstream, or middle portion of a sandbar or cobblebar. Backwaters were classified according to their position in the river (bank and mid - channel). Bank backwaters occurred in sandbars or cobblebars attached to the bank, and channel backwaters were associated with sandbars or cobblebars in mid channel. Bank and c2annel backwaters were further classified according to area (m) as requested by FWS: - <20 - >20<200 - >200<500 - >500<1000 - >1000 Tabular summaries for number and area of backwater types were produced for each individual site and the Island Park, Jensen, Ouray and Sand Wash sites were also considered as a total. Linear regression analyses were flow and backwater number vs. combined four upper sites. conducted for backwater area vs. flow at each site and for the Results and Discussion Island Park Table 1 (Appendix A) presents the area (m2) of each class for each flow at the Island Park site. An inverse relationship existed between flow and area. Backwater area consistently increased as flow was decreased from 5,260 cfs to 1,101 cfs. Two s~bstantial increases o~curred: backwater area increased from 8,575 m (2.1 ac) to 11,160 m (2.82ac), a 30% change fro~ 2,423 cfs to 1,773 cfs, and from 13,349 m (3.3 ac) to 20,070 m (5.0 ac), a 50% change from 1,430 cfs2to 1,381 cfs. Backwater area was maximized at 1,101 cfs (22,153 m). Isolated pool area generally increased as flow decreased; however, a substantial decrease occurred at 1,430 cfs.