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is achieved with a release of 99,900 ac-ft of water from Lake McConaughy (in <br />addition to a small volume of Tamarack I water). <br />. February and April are the typical months that the peak flow of Program water is <br />possible as a result of system capacity and the potential for reregulation in Johnson <br />Lake. <br />Shortages to the 5,000 cfs target flow occur for various reasons for Case I, including: <br />• North Platte River capacity at North Platte - The modeled capacity of 3,000 cfs at this <br />location on the North Platte limits the release to the river from Lake McConaughy. <br />• Capacity and ramping rates of the Keystone Diversion, capacity in Sutherland Canal, and <br />capacity and ramping rates at the North Platte Hydro Return - the flow diverted at the <br />Keystone Diversion is influenced by the capacities and historical flows at all three of <br />these locations. On occasion, one, two, or all three can limit the amount of Program water <br />that can be returned to the South Platte River to circumvent the choke point on the North <br />Platte River. <br />• Regulating capacity in Johnson Lake, both volume and time of year per the "Bypass <br />Agreement" - Reregulation in Johnson Lake is limited to the months of February, March, <br />and April. There are situations when reregulation in other months may better coincide <br />with available historical system capacities. The limit of 4,000 ac-ft of reregulation <br />provides peaking flow typically for one day. The use of the Johnson Lake reregulation to <br />achieve the 5,000 cfs target is made when the remaining capacity in the J-2 Return is the <br />highest, and therefore consumes the reregulation volume in about 1 day. <br />5,000 cfs Program water - Case II (Districts Bypass): <br />. In a113 types of year classifications, Average, Wet, and Dry, the average peak <br />Program water reaching Overton is 2,500 cfs. The average volume for the 3 day <br />pulse flow is approximately 14,500 ac-ft. The shortage to the target volume ranges <br />from 15,100 ac-ft to 15,300 ac-ft on average for the target three-day period. These <br />flows at Overton are achieved with a release from Lake McConaughy of ranging <br />from 41,100 ac-ft for Average years to 46,300 ac-ft in Wet years (in addition to a <br />AOWLE Page 34 of 58 January 29, 2008 <br />PRRIP - Draft Water Management Study, Phase I