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will not be possible. Wydoski and Wick (1996) discussed in depth the ecological importance of floodplains to riverine fish communities and identified strategies to enhance or restore flooded bottomland habitats to assist recovery of endangered fishes in the Upper Colorado River Basin. They felt that it is imperative to integrate the control of nonnative fishes and augmentation/restoration stocking of captive-reared razorback sucker with habitat enhancement/restoration efforts. Enhancement or restoration of biological, chemical, and physical conditions that are perceived to be important in nursery sites for razorback sucker can be accomplished by: 1) removal of levees to allow periodic flooding of lowlands, 2) providing a longer duration of inundation in floodplains, embayments, and backwaters by reoperation of releases from reservoirs, and 3) reconnection of the main channel with off-channel oxbow lakes and ponds. The removal of levees coupled with higher spring releases that mimic the historic hydrograph from upstream dams provided the best way to reconnect mainstem and tributary rivers with productive floodplain areas. Such removal should be done on low fl oodpl ai n terraces on public properties that can be easily reconnected with the main channel and where thorough, followup evaluations can be made. However, some nonnati ve fi shes that are establ i shed i n the upper basi n wi 11 flourish in productive off-channel habitats. Tyus et al. (1982) estimated that 76.4% of the fish community in the Upper Colorado River Basin is composed of nonnative fishes. Predation and competition on larval razorback sucker by nonnative fish is probably the primary factor that drastically reduces or prevents recruitment of this species today. If the duration of inundation of off-channel habitats is short, razorback suckers will not grow to a size where predation and competition by nonnative fishes is no longer a principal factor in their survival. Floodplain habitats that are ephemeral will not provide enough time for razorback sucker larvae to reach a length of 1 inch. Since nonnative fish species dominate backwater habitats (up to 90-99% based on ISMP data [McAda et al. 1994]), razorback sucker larvae that enter the river as ephemeral floodplains recede will be extremely vulnerable to predation since razorback sucker larvae constitute the only wiggling food items in the spring. Based on Papoulias and Minckley's work (1990), about 2 months is required for razorback suckers to reach a length of 1 inch. Razorback sucker that are about 1-inch long are no longer vulnerable to predation by some predators such as red shiners based on the gape size work by Todd Crowl. If the duration of flooding these habitats is longer, nonnative fishes will flourish and continue to adversely affect larval and juvenile razorback sucker. Wydoski and Wick (1996) agreed with Stanford (1994) who believed that the negative nonnative fish interactions may limit the recovery of razorback sucker regardless of possible streamflow provisions. They also felt that recovery of this species may be limited unless adequate control measures can be implemented in upstream, and particularly in downstream reaches of main channels, where razorback sucker larvae drift as the flooded areas recede following high streamflows. If adequate control of nonnative fishes cannot be achieved, they suggest that human intervention may be required to rear razorback suckers in predator-free, off-channel habitats so that their populations can be maintained through augmentation stocking. Of the four "large-river" endemic, warmwater fishes that are listed endangered in the Upper Colorado River Basin, the Recovery Program considers the razorback sucker the highest priority species for recovery. While razorback 23