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River, had the fewest pools, and stratum 3, a mostly canyon bound reach with the greatest gradient (0.16%), had the most and deepest eddies (Tables I and 2). WUA varied among strata depending on the habitat suitability curve used (Table 3). The daytime resting curve developed from Yampa River data showed stratum 3 averaged 7.3 m2 perl00 m2 of surface area; the other strata all averaged <4.3. The daytime resting curve gave highest scores for habitats> 1.2 m deep. The night foraging curve, also developed from Yampa River data, and the White River curve showed similar results because the HSI's were similar (Appendix 1). All strata had similar WUA for these two curves, with stratum 3 the highest score of65.4 m2 per 100 m2 surface area and stratum 1 with the lowest score of 46.8. Mesohabitat Composition vs. Discharge Habitat composition changed little among the three experimental flows (Table 1), in part the result of the small range of discharge (339--552 cfs). Pool, riffle, run, and eddy habitats are characterized as to width, depth, and velocity in Table 2. As expected, all increased with increasing flow. To examine a wider range of flows, we simulated the habitat-flow relation. The modeled habitat composition for flows between 150 and 600 cfs was stable at 32% riffles, 33% runs, 10% pools and 25% eddies; however, as flows dropped below 150 cfs, riflles increased to approximately 42% and eddies decreased to 13% (Figure 7). Riffle Wetted Perimeter and Area vs. Discharge Wetted perimeter-discharge relationships for individual cross sections showed a range from classical fast rise and abrupt turn to an asymptote with an obvious curve break to a linear relation with no obvious curve break (see Appendix 4, cross section 10102 for classical relation 10