Yampa River Basin Research Final Synthesis Report

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The Aquatic Wildlife Management Plan encompasses the entire basin, including the Little Snake River, from its headwaters to its confluence with the Green River, and the upper Green River watershed, including Vermillion Creek, downstream to the Utah state line. These reaches provide habitat for the four listed endangered fish species, as well as a variety of other native species. The CDOW recommended that the Yampa River downstream from Williams Fork be managed primarily for endangered and other native aquatic wildlife, and that non - salmonid nonnative fish populations be controlled as necessary to protect native fish populations and enhance recovery of federal and state listed endangered species. CDOW further recommended that northern pike, smallmouth bass and channel catfish removed from the river be stocked in off - channel ponds in the middle Yampa River reach and possibly Elkhead Reservoir in accordance with nonnative stocking procedures. These procedures were developed by the states of Colorado, Utah, Wyoming and the USFWS to provide guidelines for stocking nonnative fish without impacting endangered fishes or impeding their recovery in the Upper Colorado River Basin. CDOW also recommended continuation of research in the lower Yampa River to determine the relationship between instream flow and habitat for native fish species and to define year -round instream flow needs. The low flow studies conducted in 1996 and 1997 were a part of this research and provided base flow recommendations for mid - summer to early fall. Instream flow needs at other times of the year still must be determined. As part of its control program for non - salmonid nonnative fish species in the lower Yampa River, CDOW has removed angling limits for channel catfish, smallmouth bass, and northern pike in this portion of the river. CDOW hopes to determine if removing angling limits of nonnative species will allow sport anglers to continue to catch these warm water fish while reducing their impact on endangered fishes in the river. 3.3. Conclusions of Researchers and RIP Biology Committee The Yampa and Green Rivers are critical for the maintenance and recovery of the endangered fishes of the Upper Colorado River Basin. The relatively natural hydrograph of the Yampa is important not only to fish inhabiting the Yampa, but to those in the middle Green River, as well. The middle Green, in turn, is vital to sustain the Yampa River populations by providing nursery habitat unavailable in the steep, narrow canyons of the lower Yampa. The Biology Committee, in providing direction to research in the Yampa River, concurred with the findings of Modde et al. (1999) but declined to endorse augmenting flows to meet the low -flow recommendations if doing so would adversely impact spring peak flows. The Biology Committee believes spring peak flows are more important than low flows to the survival and ultimate recovery of the endangered fishes. The RIP supported the CDOW in its preparation of the Aquatic Wildlife Management Plan for the Yampa River to address issues that include conflicts between nonnative sport fish and native endangered fish in the basin. Due to competition and predation, nonnative fish represent a significant challenge to the recovery of endangered fishes. Flows are highly variable in the Yampa River both within and between years. Spring snowmelt and localized heavy rainfall events contribute to variability within years, while longer periodic wet and dry cycles are responsible for differences between years. Native species evolved with and are adapted to such a highly variable flow regime. Spring floods are important for scouring and transporting sediments, prepare spawning beds and maintain nursery habitats. In streams where the natural flow regime has been highly modified by dams and reservoirs, native species have not fared well. On the other hand, nonnative species not adapted to a highly variable flow regime may benefit from dams that modify the natural flow regime and reduce flow variations. Therefore, maintenance of a relatively natural flow regime is conducive to a healthy native fish community in the Yampa River and ultimate recovery of endangered fishes in the Upper Colorado River Basin. 12