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estimated start dates to accommodate ramping rates. More input is required by the user in <br />evaluating the 5,000 cfs target flow compared to the 800 cfs irrigation season target. This <br />is because the operations for the 800 cfs are simply turned on and the 5,000 cfs requires <br />identification of periods with capacity in the system and determination of necessary <br />operations. <br />The target period for the 5,000 cfs, Case I scenario is generally February, March, or April <br />to allow the use of the Johnson Lake reregulation storage. With this starting point, the <br />available capacity in the North Platte River at the choke point and the remaining capacity <br />in the J-2 Return typically determine the best target release period. The user must also <br />determine when and if to store, bypass, or release flows at Johnson Lake. In addition, to <br />supplement the peak flow from the J-2 Return, operation of the 3effrey Return a day prior <br />to the anticipated peak flow is set by a user variable. Exceptions to these considerations <br />do occur as a result of the historical flow data used in the routing tool. <br />In the scenario of a 5,000 cfs target and Case II, the maximum deliveries are governed by <br />the maximum remaining capacity at the North Platte River choke point. Periods identified <br />for this scenario range from November to April. The month of May is typically avoided <br />due to the higher river losses incurred. <br />The 800 cfs target flow runs from May through September. The target period for the 800 <br />cfs flow evaluated in this study is from May 1 to September 30. USFWS indicated that <br />the 800 cfs flow is intended to augment flows from May 11 to 5eptember 15 as outlined <br />in the Instream Flow Recommendations Document (see FWS Meeting Notes in Appendix <br />1). The difference in volume of the two durations is approximately 40,000 ac-ft at <br />Overton. The release from McConaughy is capped based on an estimated required release <br />determined by travel times and losses to Overton. The start date to meet the target flow <br />on May 1 varies from year to year subject to remaining capacities and ramping rates for <br />Case I. The Case II scenario relies solely on the capacity at the North Platte River choke <br />point, and also varies the start date subject to ramping rates on the North Platte River. <br />Output for each scenario includes the following summary: <br />13042E Page 29 of 58 January 29, 2008 <br />PRRIP - Draft Water Management Study, Phase I