PRRIP Request for Proposals Draft (2)

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PRRIP - ED OFFICE DRAFT 12/04/2007 June 2, 2007. The time period for this pulse release will be between February 1 and Apri130, 2008. The FWS Environmental Account manager will be able to give approximately ten (10) days notice prior to pulse flow initiation. Hypotheses Testing Priority hypotheses in the Program's Adaptive Management Plan (AMP) do not indicate that a flow under 5,000 cfs would remove vegetation or change geomorphology in a significant enough way to provide benefit to the target species. However, the Unsteady Flow and SEDVEG Gen3 models used predict the impact of flows under the Flow/Sediment/Management (FSM) hypothesis can be evaluated at this lower flow. Infortnation gathered under this Pilot Study will be used to evaluate and improve these models and/or determine the need for the use or development of different models. Objectives The Pilot Study will allow for tracking of the water from Lake McConaughy through the associated habitat area. This effort will acquire data to evaluate how modeled flow and water surface elevation relate to the actual measured flows and water surface elevations. Key study objectives and activities include: • Track flow magnitude and timing from Lake McConaughy through the associated habitats and compare to flows modeled in the Unsteady Flow Model. • Measure water surface elevation in the associated habitats and compare to modeled water surface elevations in the SEDVEG Gen3 model. • Determine if the Unsteady Flow and SEDVEG Gen3 models are sufficiently accurate to model higher pulse flow events. ? • Track the travel time of the leading edge of the pulse flow. .' ' C 1-,,? 0-4?.?.? . Pilot Study Measurements At a minimum, the following measurements will be obtained: Flow data from existing flow gage network including gages at Keystone, Sutherland, Roscoe, North Platte, Maxwell, Brady, Cozad, Overton, Cottonwood Ranch, Kearney Canal Diversion, Odessa, and Grand Island. Additional stage gage information will be obtained near Gibbon and Wood River from existing USGS gauges. In addition, stage information will be obtained at key cross-sections used in the Unsteady Flow and SEDVEG Gen3 models. Transit losses/attenuation to North Platte, Nebraska for EA water passing Keystone Diversion has been tentatively estimated by the Environmental Account Manager to be 50%- 40%-30%-25%-20%-15%-10%-10% for each respective day that flows are ramped-up in the North Platte River below Lake McConaughy. There is an assumed 2-day travel time for water released from the Lake McConaughy to reach the North Platte gage. The transit losses/attenuation to Overton, Nebraska for EA water passing Central Diversion Dam has been tentatively estimated to be 70%-60%-50%-40%-30%-25%-20% for each of the respective days that water is bypassed down the Platte River. A 2-day lag time is assumed 4