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increased and eddies decreased. Adult Colorado pikeminnow habitat was estimated for three sets of habitat suitability criteria and applied to the White River physical habitat simulation at discharges ranging from 0.028 to 17.0 m3/s (1-600 fe/s). The first criterion used White River data from previous studies. It showed an almost linear increase in usable habitat as flows increased from 0.028 to 17.0 m3/s. The second criterion used night foraging data from the Yampa River (1996 and 1997). It showed usable habitat area almost identical to that of the White River data, the result of similar suitability indices for depth and velocity. The third criterion was for daytime resting fish, also developed from Yampa River data. This showed low usable habitat score for all White River flows. This was the result of the Yampa River data showing daytime use of pools and runs> 1.2 m deep; however, these depths were rare in the White River. White River Colorado pikeminnow apparently found suitable daytime resting areas in other habitats < 1.2 m deep, e.g., undercut banks and within channel structure. The riffle surface area-discharge relationship was nearly linear for all flows examined, and thus no curve break was identified. The wetted perimeter-discharge relationship, however, was non-linear and increased rapidly with discharge between 0.028 and 4.24 m3/s (1 - 150 fe/s) and then gradually approached a plateau near 14.2 m3/s (500 fe/s) before again increasing at 15.6 m3/s (550 fe/s). Curve break analysis found that at discharges below of 4.2 m3/s wetted perimeter decreased rapidly. Curve breaks were also calculated for width, depth, and velocity and yielded values similar to that of wetted perimeter. Historical White River discharge during the base flow period (August-October) 1923 through 1997 dropped below 5.7 m3/s (200 fe/s) less than 5% of the time and below 4.2 m3/s less 7