PRRIP Governance Committee Meeting and Materials

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? Without an EA bypass (and reregulation in the CNPPID system), any pulse flow release in WY08 would essentially be equal to the J-2 outflow capacity of approximately 1,950 cfs, plus whatever baseflow was present in the river at Overton at the time. Information could still be obtained concerning ramp rates, travel times, coordination procedures, etc., but it is the Service's assessment that such an initial pulse flow release would be of much lesser utility. Future larger magnitude pulse flow tests will most likely involve EA bypass so testing any aspect of the coordination and water tracking related to bypass will provide benefits. If a sufficiently large flow occurs with enough advance warning from the South Platte River area in Colorado such that CNPPID's diversion capacity (2,250 cfs) is likely exceeded, then it may be possible to augment such a flow with EA water. However, the existing ramp rate limitation of 300 cfs at Lake McConaughy would probably limit the ability to provide maximum flow in the North Platte River at North Platte that is timed-up properly with the South Platte River (6 days to reach a 1,800 cfs EA release from McConaughy). Without an intentional EA bypass at the CNPPID diversion, approximately 2,250 of the available flow at the North Platte and South Platte River confluence would be diverted, and if sufficient water was not available from the lower portion of the CNPPID system, then the effectiveness of augmenting such a South Platte River flow would be diminished. (2) Anticipated Benefits: 40 Given the existing NWS flood-level of 1,980 cfs at North Platte, an initial EA release is planned within this capacity and provides opportunities to (a) better quantify travel times and pulse interaction with river gains, (b) monitor water levels in areas of concern currently being addressed by the Program's North Platte River Restoration and Enhancement Project, (c) obtain information concerning whether future ramp rates can be safely increased, (d) provide for appropriate advance notification and monitoring at downstream diversion facilities and coordination efforts between the EA Manager, Districts, Program Executive Director, NE Department of Natural Resources, Program participants, and the National Weather Service, and (e) Monitor and assess the potential for damages under more aggressive or larger-magnitude pulse flow implementation in future years (e.g., reregulation of larger volumes of EA water at Johnson Reservoir). (3) Magnitude, duration, and effectiveness of peak flow events over the previous year: As discussed earlier, there were three natural "pulses" during the winter/spring of 2007. Mean daily flows (provisional) of 9,350 cfs, 4,870 cfs and 3,730 cfs were recorded at Kearney on February 11, Apri125 and June 2, respectively. It should be noted that the February 11 value occurred during a period of missing recard, andlor gage height affected by icing conditions. The natural "pulse" or "peak flow" events that occurred in 2007 are not considered over- riding factors when planning for an initial pulse flow release test of relatively low • magnitude in 2008. The magnitude, duration and effectiveness of the previous year's peak flows will be a much more important factor to consider as the ability to provide greater magnitude EA pulses is achieved (e.g. if greater magnitude pulse flows result in Water Year 2008 EA AOP 13 October 15, 2007