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watershed, and (4) regression algorithms that smooth and fill in missing water <br />temperature measurements. Turbulence is assumed to thoroughly mix the stream <br />vertically and transversely. <br />Sediment Load <br />Relatively little information is available about sediment changes in the <br />Gunnison and Colorado rivers. Information from two reports (Thompson 1984; <br />Elliott and DeFeyter 1986) was summarized to evaluate changes in sediment load <br />carried by the two rivers as a result of the Aspinall Unit. <br />streamflow <br />Our primary method of assessing the effects of the Aspinall Unit and <br />related projects on streamflow was to compare measurements at two long-term <br />USGS stream gaging stations--Gunnison River at Whitewater (begun in 1917) and <br />Colorado River at Cisco (begun in 1914). Unfortunately, irrigation diversions <br />began as early as 1880 in the two basins and we have no reliable method of <br />accounting for these diversions in the available streamflow data. In <br />addition, two large water diversions (Uncompahgre tunnel in 1909 and the <br />Redlands Diversion Dam in 1918) were constructed at about the same time that <br />flow measurements began. These projects diverted water from the rivers but <br />did not provide any storage. Also, because the water was used for irrigation, <br />some of the diverted water returned to the rivers upstream from the selected <br />gaging stations. Therefore, we believe that the measured streamflow probably <br />underestimates the historic streamflow that occurred during non-runoff <br />periods, but probably approximates the streamflow that would have occurred <br />during runoff_ periods when only a small portion of the flow could be diverted. <br />Dam construction began in the Gunnison Basin with the closure of Taylor Park <br />11 <br />