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<br />~~ <br />t>~ <br /> <br />" <br /> <br />the Colorado River at Lee Ferry, and the Log Normal distribution of those <br />flows. <br /> <br />V. Software <br /> <br />. <br /> <br />The Bureau of Reclamation's 24-month operation plans for the Colorado River <br />Reservoir System are routinely generated on software developed especially for <br />that purpose. The Upper Colorado River Commission has developed a similar <br />software system which has been in use since 1987. The Commission staff <br />improved this program for this study in two substantial ways. First, <br />operation of the reservoir system has been expanded from 24 months to 60 <br />months. Second, flood control capabilities have been added as described in <br />the 1982 Hoover Flood Control Regulations as established by the U.S. Army <br />Corps of Engineers. This allows the program to determine the predicted space, <br />and calculate the creditable and effective space. By this procedure it is <br />possible to identify any flood flows which would be forced from the system <br />under normal operations for five study years under various hydrologic <br />scenarios. <br /> <br />VI. Procedure <br /> <br />Five year hydrologic scenarios at Lees Ferry were identified for the 5%, 25%, <br />50%, 75%, 90%, and 95% probabilities of nonexceedence. The individual <br />hydrologic scenarios were distributed equally among each of the five years. <br />The monthly flows within each of these years were determined according to <br />proportionate flows as established for the various probabilities as used in <br />the Bureau of Reclamation for 24-month studies. The first year of all studies <br />were adjusted to allow the forecast to occur for the first three months of <br />water year 1992. <br /> <br />Virgin flows were then adjusted for assumed annual depletions from 1992 <br />through 1996. Annual depletions were adjusted according to the rate of growth <br />contained in the Bureau of Reclamation "modified depletions" as contained in <br />the CRSS model. Depleted flows were then disaggregated for reservoirs <br />upstream of Lake Powell. <br /> <br />With the unregulated inflows established for all reserVOlrs, the system was <br />operated for a five year period for each probability scenario. The reservoirs <br />above Lake Powell were geuerally operated to maximize storage contents. Lake <br />Powell was operated to meet the release objectives established by the <br />operating criteria. A minimum of 8.23 million acre-feet per water year were <br /> <br />3 <br />