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<br />Gunnison Study Period o.cord <br />'. <br /> <br />. <br /> <br />TABLE <br /> <br />C) <br />c:') <br />(~) <br />~ <br />00 Para~eter <br />~ <br /> <br />ANNUAL FLOW DATA <br />REPRESENTATIVE STREAMFLOW POINTS <br />Flow Values in Acre-feet <br /> <br />Period of Record <br /> <br />Taylor River Lake Fork <br />at Al~ont at Gateview <br />1911-1985 1938-1986 <br />246,000 174,600 <br />228,900 160,800 <br />92,900(1977) 64,300(1977) <br /> <br />Average Annual Flow <br /> <br />1952-83 Average Flow <br /> <br />Minimu~ Annual Flow (Year) <br /> <br />Minimum 2 Year Avg. (Years) 147,100(1977-78) 93,400(1976-77) <br /> <br />Minimum 3 Year Avg. (Years) 165,200(1976-78) 108,500(1954-56) <br /> <br />Minimum 5 Year Avg. (Years) 178,700(1974-78).137,500(1977-81) <br /> <br />08/18/87 Page 2 <br /> <br />Below Crystal <br />(from CRSS) <br /> <br />1906-1985 <br /> <br />1,344,800 <br /> <br />1,215,500 <br /> <br />396,300(1977) <br /> <br />651,700(1976-77) <br /> <br />801,800(1954-56) <br /> <br />945,100(1931-35) <br /> <br />The representativeness of the proposed study period vis-a-vis very long <br />term hydrology can only be assessed indirectly, e.g., through examination of <br />tree ring data, because streamflow records are not of sufficient length. . <br />Examination of these surrogate records could indicate whether very long terj.'(~ <br />trends are greatly different from recent history but cannot provide practical ~ <br />guidance as to alternative study periods which might be used. Nevertheless, a <br />review of existing tree-ring data for the basin will be made and discussed. <br /> <br />The availability and quality of .data on streamflows and water uses in the <br />Gunnison basin also places some restrictions on the study period which can <br />practically be used. Only the most reeent records reflect current river <br />adminstration and project operations. Diversion records for most water rights <br />have been kept systematically only since the 1950's and in machine-readable form <br />since the mid 1970's. These considerations preclude the study period from going <br />back earlier than about 1950. <br /> <br />Even since 1950, the pattern of streamflows in the Gunnison and Uncompahgre <br />Rivers has been significantly affected by the staged development of the <br />Curecanti Project, which was eompleted in 1978. Thus only about the last 10 <br />years of streamflow and diversion records are truly representative of current <br />river adminstration and operations. However, the last 10 years are not <br />hydrologieally representative and do not contain critical dry spells. <br /> <br />WBLA Ine. 1909 Broadway, #3 Boulder, Colorado 80302 <br />