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<br />to mora accurately determine the annual and monthly adjust- <br />ments required to the gage records for the Arkansas River <br /> <br />below John Martin Reservoir. <br /> <br />6. Comparison of 1970s State line Usable Flows with Others <br />Periods of Drought <br /> <br />Precipitation records for several stations in the <br /> <br />Arkansas River Basin were gathered and reviewed. These <br /> <br />records show that the period 1974-1979 was a period of below <br /> <br />average precipitation in eastern Colorado. The records also <br /> <br />show other drought periods in the 1930s and 1950s. The <br /> <br />average annual precipitation during the 1970s drought <br />generally was higher than either of the two previous drought <br />periods. Although usable stateline flows declined somewhat <br /> <br />in each of these earlier drought periods, these declines <br /> <br />were of a far lesser magnitude than was experienced in the <br /> <br />1970s drought. See, Graph 1C of Usable Stateline Flows. <br />7. Effect of Major Flood Events <br /> <br />During usually prevailing flows, streamflow is general- <br /> <br />ly reliable and of sufficient accuracy to be used in a mass <br /> <br />diagram analysis. According to the "Interim Report of <br />Committee on Engineering Data and Studies," June 26, 1947, <br /> <br />prepared by the Arkansas River Compact Administration: <br /> <br />Inaccuracy in the data is probably greatest during <br />infrequent periods of major floods, when rates and <br />volumes of flow are abnormal, channel conditions <br />are unstable, and direct measurements are diffi- <br />cult, if no 'impossible, to make. Comparisons at <br />such times may give misleading results. The <br />inclusion in totals of such infrequent and abnor- <br />mal volumes, whether accurately or inaccurately <br />determined, tend to distort the long-term average <br />values, and may therefore lead to false water <br />supply conclusions, since no one can forecast with <br />accuracy either the frequency or magnitude of <br /> <br />-32- <br />