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<br />OC20oo <br /> <br />i. e. after 1950. Frequency analyses were made of the annual canal diver- <br /> <br /> <br />sions for selected canals and for the Arkansas River at Canon City and <br /> <br />the State Line. The results are shown in Table No.6 along with the <br /> <br /> <br />annual maximum and minimum flows and diversions. An example of the <br /> <br /> <br />printouts is given in the appendix for the Rocky Ford Highl ine Canal <br /> <br /> <br />where the annual diversions were arranged in deLending order of magni- <br /> <br /> <br />tude and plotted against years. <br /> <br /> <br />The purpose of these studies is to show the stabil ity of the <br /> <br /> <br />historic supply. For example, if the flow or diversions expected <br /> <br /> <br />50 percent of the time is approximately equal to the flow or diversions <br /> <br />expected 80 and 90 percent of the time, the supply is relatively stable. <br /> <br /> <br />Inspection of Table No.2 reveals the large variability of the supply <br /> <br /> <br />at Canon City and this, In turn, is reflected by the water available to <br /> <br />the various canals shown. <br /> <br /> <br />An examination of this table shows that the Rocky Ford Canal has <br /> <br /> <br />a dependable supply. Some variations are to be expected because precipi- <br /> <br />tation and other factors influence the amount of water diverted. The <br /> <br /> <br />Fort Lyon Canal Diversions shown in this table are representative of a <br /> <br /> <br />canal which experiences severe shortages in low runoff years. <br /> <br />The maximum and minimum flows at the state line of 1,317,590 acre.. <br /> <br />feet in 1942 and 31,630 acre-feet in 1940 are indicative of outflow <br /> <br /> <br />from the state prior to storage. in John Kartin Reservoi r. Since its <br /> <br /> <br />construction, the maximum outflow was 776,800 acre-feet in 1965 and the <br /> <br />minimum was 60,800 acre-feet in 1963. <br /> <br />In order to establish that the frequency analysis of the total <br /> <br /> <br />period since the middle 1920's is indicative of the present-day surface <br /> <br /> <br />supply, further investigations were made of this approach by dividing <br /> <br />the period of record into three regimes, 1924 or 1927 through 1941 <br /> <br />(before John Kartin), 1942 through 1950, and 1951 through 1966, inclu- <br /> <br /> <br />sive. Investigations of river flows began in 1924 and ditch diversions <br /> <br /> <br />in 1927. Because this analysis is primarily for analyzing trends, the <br /> <br /> <br />exceedingly large runoff years of 1942 and 1965 were excluded from the <br /> <br /> <br />analysis. The period 1943-1950 is after John Martin, but before appre- <br /> <br /> <br />ciable well pumping in the basin. Therefore, the period 1951-1966 <br /> <br /> <br />shows essentially current conditions with operation of John Martin and <br /> <br /> <br />material well pumping. <br /> <br />- 17 - <br />