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0 <br />Objectives: <br />Phase I objectives will be the focus of work to be accomplished in 1996. Work on Phase II <br />objectives are contingent upon occurrence of low -flow conditions in the Yampa River as <br />identified in Phase I. <br />Phase I: <br />1. Estimate the range of low -flow conditions that impede or prevent physical upstream <br />passage of Colorado squawfish at Cross Mountain Canyon, and at the Patrick Sweeney <br />and Maybell Canal diversion structures or any additional limiting reaches identified, <br />2. Determine the historic frequency, timing and duration of these flow conditions and <br />determine if existing data on population abundance, movements, migration, larval <br />production, and growth suggest whether the Colorado squawfish population has been <br />adversely affected historically by these low flow events, <br />Phase II: <br />3. Evaluate passage by Colorado squawfish through these potential barriers during the target <br />low -flow periods with respect to post - spawning upstream migration to validate estimates <br />of low flows necessary to impede passage and determine percentage of population <br />affected, <br />4. Determine if the recovery of the Colorado squawfish population is adversely impacted <br />if movement is demonstrated to be inhibited by the presence of these barriers, and <br />evaluate the potential to alleviate this impediment through modification for passage and <br />flow management. <br />V. Study Area: <br />Yampa River: river miles 45 -118 <br />Cross Mountain Canyon: river miles 55 -59 <br />Maybell Canal diversion: river miles 89 -91 (in Juniper Canyon) <br />Patrick Sweeney diversion: river mile 98.5 (below Govt. Bridge) <br />Study area is based on current distribution data indicating primary home range of adult <br />Colorado squawfish extends to river mile 118. <br />VI. Study Methods /Approach: <br />Phase I <br />A study team composed of hydrologists, geomorphologists, river mechanics engineers <br />and endangered fish biologists will be assembled to perform Phase I of the study. <br />3 <br />