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000183 percent entrainment of larvae into floodplains, and monthly survival of fish in floodplains and in the main river channel. I recommend that the Recovery Program maintain and refine this model as a tool in helping to understand those aspects of the Habitat Restoration Program that are most critical to the recovery of the razorback sucker. Use of floodplains by razorback sucker depends on many factors external to species demography, including timing of availability, duration of connection with the mainstem, and ability of the floodplain to hold quality water for overwintering fish. It is also unknown ifthe inter-annual frequency of flooding is sufficient to establish and maintain a demographically and genetically viable population of razorback sucker. A recruitment model that simulates survival for the historic hydrographic record of the Green River may be necessary to provide insights into inter- annual flood frequency necessary to maintain a population of 5,800 adults. 136 Floodplain Habitat Management Plans: The following recommendations identify actions that should either be implemented immediately or should be prioritized for implementation. These recommendations are intended to provide direct and immediate guidance for initiating implementation ofthis floodplain management plan. These actions are not ordered by priority. 1. Suspend further acquisition of private property easements in the Green River Subbasin. Activities and expenditures by the Recovery Program for further acquisition of private property easements in the Green River Subbasin should be suspended, except for completion of negotiations with Thunder Ranch. Floodplain area currently accessible to the Recovery Program through coordination with State and Federal agencies is sufficient for recovery of razorback sucker. Further acquisition of easements should be continued only if potential floodplain depression area is insufficient through coordinated efforts. 2. Implement restoration and management of Thunder Ranch floodplain. The first priority of this Plan is restoration and management of the floodplains at Thunder Ranch. This floodplain is only 5 miles from the razorback sucker spawning bar and can potentially entrain large numbers of wild-produced razorback sucker larvae. 3. Coordinate management of Stewart Lake with Utah Division of Wildlife Resources, Bureau of Reclamation, and US. Fish and Wildlife Service. Stewart Lake is managed by the Utah Division of Wildlife Resources (UDWR) primarily for waterfowl. Bureau of Reclamation (Reclamation) and US. Fish and Wildlife Service (Service) have implemented remediation measures for selenium, which has been identified as a risk to fish health. Stewart Lake currently has the structural components (i.e., inlet/outlet control gates, lowered portions of levee for flooding, trenched depression for draining) for management as a 12-month depression floodplain, and the Recovery 2003 Report Recommendations,