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, ',,' HISTORICAL PRACTICE ~, Ujuf',. . ~ .,'. I -', ....., :1 fH.I"',,:\ --....11 .'" IJil~' 1 ~,~, / ,r., ': ::"'.: <- . o (_"':'.1 two. Winter Storage Release Demands t11 ~ Previous to the 1979 agreement, the rapid release of winter ~ storage water often caused the reservoir to be drained .in early spring. During thirty years of record, the reservoir was emptied of winter storage water twenty-two years. In fifteen of these years, the reservoir was emptied in April. Chart I contains the release dates and combined (Colorado and Kansas) average demands for each year. Chart II shows the distribution of these release rates. Details of these demands (times of day releases began and ended, separate demands by Colorado or Kansas) may be found in Appendix I. In all the years except 1 that the reservoir contained 22,000 acre feet of water, or less, drainage occured by April 30. As Chart III shows the one exception to this was in 1970 when drainage was completed on May 28. Continuous demand for releases at the maximum permissable rate drained the reservoir in April of 1963, 1964, 1965, 1971, 1975, 1976, 1977 and 1978. Continuous near maximum release demands (900-999 cfs) emptied the reservoir in April of 1954, 1956, 1972, and 1974. Near-maximum release rates are created' when maximum release demands are combined with a few days of less than maximum rates. Considering these as maximu. rates, the drainage of the reservoir accured at the maximum permissable rate in 11 out of 22 years. In years that the reservoir was drained after April 3D, higher reservoir contents, slower release rates and/or precipi- tation were responsible for the exteneded storage period. The need for water, a function of local precipitation, irrigation demands and river flow, determined the rates at which both Colorado and Kansas requested releases. The mean of the average rates for each year was 856 cfs 0 w-ith a standard -deviat1on.'of-r8.6- i::'fs-on -22%-. --Th'e-nie'an -of the ;~ individual daily values (566 total) was 790 cfs with a standard o6? deviation of 265. cfs or 34%. . The median (midpoint) of these I /.9~ daily demands was 882 cfs and the mode (the most common value) ~-' was 1000 cfs. Days when neither state called water, even if these were in the middle of a series of releases, were deleted. There were 76 days (out of 566 days) when Colorado called water and Kansas did not. .These days added many lower values in the computation of the average, (see 1959 releases) increased the standard deviation and lowered the means. ~~.... '-.'-'- ........ --.-