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n ~~ ~ BACKGROUND ~ The Upper Colorado River Endangered Fish Recovery Program (UCRRP) was established in 1988 to resolve conflict over competing demands for water in the upper ~ Colorado River basin. The UCRRP is a cooperative effort involving the states of ~ Colorado, Utah, and Wyoming, the U.S. Bureau of Reclamation, the U.S. Fish and ~ Wildlife Service, National Park Service, Western Area Power Administration, Colorado • River Energy Distributors Association, water user organizations, and environmental organizations. The dual purposes of the UCRRP are to recover four species of fish ~ listed as endangered under the Endangered Species Act of 1973, as amended, while ~ allowing the states to continue to develop water under the Colorado River compact. • The UCRRP developed a Recovery Action Plan (RIPRAP} that lists actions believed necessary to recover the bonytail (Gila elegans), humpback chub (Gila cypha), ~ Colorado pikeminnow (Ptychocheilus lucius) and razorback sucker (Xyrauchen ~ texanus). One set of actions within the RIPRAP consists of restoring and protecting • floodplain habitats to support and sustain species recovery. Levee Removal is one effort undertaken by the Recovery Program to restore floodplain habitats for native fish ~ use. n ~~ ~ Problem Statement Floodplain habitats are reported to be important nursery and feeding areas for ~ razorback suckers and other native fishes (Wydoski and Wick 1998). The chronology ~ of spawning and larval emergence (Tyus and Karp 1990; Muth et al. 1998), as well as a ~ linkage between juveniles and floodplains (Modde 1996), indicate that floodplain • habitats are important to early life stages of razorback sucker. However, since the operation of Flaming Gorge Dam the frequency offloodplain-riverine connection has ~ been dramatically reduced. Reduced floodplain connection frequency has occurred ~ primarily because of reduced mean annual peak flow (672 m3/s [24,000 cfs) pre-dam to • 487 m3/s [17,400 cfs) post-dam) and river bank stabilization resulting from vegetation encroachment within the active river channel (Graf 1978, Flo-engineering 1996, 1997). ~ Construction of flood control levees has also contributed to reduced floodplain ~ connection frequency in some sections of the Green River. Flo-engineering (1997) • reported the frequency offloodplain-riverine connection has decreased from occurring 2 out of 3 years pre-dam to only 2 out of 7 years during the post-dam period. This ~ reduction of floodplain connection frequency has decreased or eliminated native fish ~ access to floodplain habitats. Thus, native fish no longer benefit from highly productive ~ floodplain habitats. The influential role of floodplains in river ecology has made them the subject of ~ recent interest (Bayley 1995, Ligon et al. 1995, Townsend 1996). The annual ~ hydrologic cycle of a floodplain consists of a periodic cycle of inundation and recession, ~ typically associated with seasonal weather patterns. The general importance of • floodplains and associated riparian communities to riverine ecosystems is a central tenet of both the Flood Pulse Concept (Junk et al. 1989) and the River Continuum ~ Concept (Vannote et al. 1980). ~ The Flood Pulse Concept (Junk et al. 1989) argues that the majority of annual 1.2