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other forage species, their preservation is fundamental to the health of the entire aquatic <br />community. Once the flow for the mean of the infection points for stream width was <br />determined, the other parameters, i.e. percent wetted perimeter, average depth and <br />velocity and width/depth ratio were also determined. These were examined to determine <br />if habitat quality would be maintained at the inflection point flow level. <br />To determine if the minimum instream flow recommendation, developed by a <br />process designed to maintain adequate flow across riffles, also provides adequate habitat <br />for endangered fish, Colorado squawfish and humpback chub, habitat probability <br />functions were developed. These were based on a frequency distribution for habitat <br />types, depths and velocities for squawfish observed by the radio tracking. Habitat <br />availability was modeled incrementally with flow using the RHABSIM software package <br />(Payne 1995). <br />The passage issue was addressed by two approaches. Attempts were made to <br />identify riffles that were successfully passed at a known flow. This is only possible when <br />the radio tracking crew could document passage through a riffle at a known flow. In <br />1996 flows were in the 100 to 150 cfs range for a period of three weeks, however in 1997 <br />flows did not drop below 330 cfs. The lack of low flows during the 1997 radio tracking <br />study meant that direct observation was not possible. The alternative approach was to <br />select a minimum depth criterion for passage and use the stage - discharge relationships <br />developed on riffle areas to model the flow that provided that depth. The depth criterion <br />used was 1.0 ft, and it was assumed if a riffle had a maximum depth of one foot, passage <br />for squawfish would not be a restrictive. <br />11 <br />