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insight into which habitats are preferred. At this time, the only practicable approach for developing recommendations for summer and winter flows is to use information collected from the Grand Valley as a surrogate for more reach-specific information. However, one limitation to this approach is that razorback sucker habitat preference was not learned in prior studies in the Grand Valley because few habitat-use data were available from reaches where mesohabitats were later mapped. Habitat preferences of Colorado pikeminnow derived from the 15-mile reach can be used, but, the necessary mapping of meso-habitats (riffles, pools, eddies, etc.) at base flow levels in the Palisade-to-Rifle reach has been very limited. Such mapping is needed to discern at what discharge preferred habitat types are maxi 'Zed (see approach used by Osmundson et al. [1995] for recommending base flows in the 15-'mile reach). In the interim, it is assumed here that flow levels that maximize these habitats in the subject reaches will be similar to those that do so in the 15-mile reach. The current practicality of implementing summer flow recommendations in these reaches is particularly problematic due to the local diversions of water for irrigation and power ;production. The senior water rights associated with these diversions will necessarily dictate''! a minimum amount of water delivered through these two reaches, particularly during the irrigation season. When this amount is added to the amount already recommended for endangered fish habitat in the 15-mile reach, the minimum delivery amount may be more or less than the flow level that most benefits endangered fish within these reaches. Assuming that these senior water rights will continue to be exercised and the amounts diverted remain constant, any lowering or raising of flows in the subject reaches will also be experienced downstream in the 15-mile reach. Thus, senior diversion rights and endangered fish flows in the 15-mile reach place constraints on flexibility of flow management in the reaches upstream of the diversions, particularly during late summer and early fall. This report provides recommendations for summer and winter flows in the Palisade-to-Rifle reaches based on what is considered best for the endangered fish within these reaches and then discusses the current constraints imposed on implementing these recommendations. In determining optimum spring flows, Osmundson and Kaeding (1991) concluded that the greatest value of high flows, typical of spring, was the year-round benefits provided by the scouring and flushing action of the flood waters (i.e., channel maintenance, removal 6