8249 - Laserfiche WebLink

Home Browse Search

The role of variation has been reported to have particular significance to the ecology of lotic fishes. Several studies have shown that native fishes tolerate higher flow events than nonnative fishes in arid streams (Meffe and Minckley 1987, Minckley and Meffe 1987, Deacon 1988, Hoffnagle et al. In review, Muth and Nesler 1993) in the Southwest. Even if the current flow scenario would allow for the persistence of endangered fishes in the Yampa River, we know that additional depletions will occur over time. Two studies of the potential increase of human demands within the Yampa River basin (Yam va River Alternatives Feasibilitv Studv - Hydrosphere 1993 and, Yampa Vallev Water Demand Study - BBC Research and Consulting 1998) have suggested that water depletions will grow by approximately 49,000 acre feet annually to satisfy human demand over the next 50 years. Instances and duration of lower baseflows are likely to increase over present conditions. The number of years with high or optimal baseflow conditions (for endangered fishes) will most likely be fewer, while the number of years with low baseflows will increase in frequency. Given this scenario, we recommend the development of a water management plan for the Yampa River. We recommend this water management plan use 93 cfs as a target for the minimum instream flow. However, we also recommend that the flow management plan not be restricted to achieving 93 cfs in 100% of the years, but include examining the frequency, magnitude, and duration of flow events under 93 cfs observed during the period of record (1916-1998). This report was directed to determine the baseflow needs of fishes, and does not prioritize the needs of high spring flows as spawning cues and channel forming forces versus the baseflow needs of fishes during the summer months. Crucial to the next phase of a water management plan will be to evaluate and prioritize the temporal distribution of flow. The flow management plan needs to provide a suite of operational strategies on how a "carve out" and other water rights could be administered to satisfy both the high-flow needs of endangered fishes and the baseflow recommendation provided in this report. 14