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<br />. ..,.,.) <br />l. ..j.. , <br /> <br />. <br /> <br />The purpose of this report is to provide a basis for increased cooperation <br />and understanding among all concerned with the coordinated operation of <br />the project. <br /> <br />The report has two main parts. One part is historical and reports the <br />results of actual operations through water year 1970. The other <br />presents operation plans for water year 1971. <br /> <br />In establishing the general plan for future operations, three possibilities <br />are considered: (1) a reasonable maximum water supply which might be <br />mqlected, (2) a reasonable minimum, and (3) the most probable supply. <br />These three conditions of water supply are derived by statistical analysis <br />of historical water supply data. Statistically, there is one chance in ten <br />that the actual runoff will either be greater or less than the volumes <br />indicated as reasonable maximum and reasonable minimum. Annual inflow <br />of a magnitude equaled or exceeded 50 percent of the time is considered the <br />most probable supply. Exhibit 1 illustrates the probability curves used. <br />Once established, however, the Annual Operating Plan does not remain <br />rigid. From time to time revisions are made as new information becomes <br />available. Flexibility is a keynote of the plan. <br /> <br />Report on Operations during Water Year 1970 <br /> <br />. <br /> <br />Ruedi Reservoir <br /> <br />Water in storage in Ruedi Reservoir on October 1, 1969, was 96,769 acre- <br />feet. The reservoir was drawn down during the month of October reaching <br />a content of 80,079 acre-feet on November 1. As requested by fishery <br />interests, the reservoir releases were gradually reduced early in <br />November to benefit the brown trout spawn. The desired flow of 95 c. f. s. <br />was reached on November 4. This flow of 95 c. f. s. below the reservoir <br />was maintained until January 5 when the threat of damage from ice jams <br />in the river near Basalt required that the outflow be reduced to natural <br />inflow which was about 50 c. f. s. Releases continued to be limited to <br />inflow until about March 1. <br /> <br />On March 1, 1970, the storage was 74,900 acre-feet instead of the 67,700 <br />acre-feet anticipated in the operating plan. Forecasts of the April through <br />July inflow were made on March 1, based on snow course data, and the <br />releases adjusted so as to pull the reservoir water level as low as possible <br />and still refill by July 1 under most probable conditions. Subsequent <br />forecasts were made on April 1 and May 1 and the releases adjusted <br />accordingly. During most of this period, designers criteria of a maximum <br />drawdown of 5 feet per week controlled the operation. The reservoir was <br /> <br />. <br /> <br />2 <br />