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Gunnison River /Aspinall Unit Temperature Analysis -Phase I <br />Page 6 <br />4. TEMPERATURE ANALYSIS OF THE THREE ASPINALL UNIT <br />RESERVOIRS <br />An analysis was conducted to determine how each reservoir affected Gunnison River <br />temperatures. The data used for this analysis included electronic data from the National <br />Park Service (Matt Malick), and U.S. Fish and Wildlife Service (George Smith). <br />Information from several reports provided by Bret Johnson of Colorado State University <br />were also used (Johnson, 1997, 1998, and 1999). The focus of this analysis was the <br />summer months, which is when most of the available data were taken and is the subject <br />of this report. <br />Figure 2 shows temperatures over time at two locations in the river-reservoir system. <br />These locations include the Gunnison River inflows into Blue Mesa and Gunnison River <br />below Crystal. <br />The impact of the three reservoirs is to cool the river, especially during the summer <br />months when there is an estimated 3.5 °C difference in temperature between Blue Mesa <br />inflows and Crystal releases. Also, it appears that the reservoir system causes a lag in the <br />timing of when peak temperatures occur of about 1 month. <br />zo <br />18 <br />16 <br />14 <br />~-Below Crystal -Estimated trom Profiles <br />-Below Crystal - FWS <br />~-Upstream of BMR - NPS <br />12 <br />° <br />n 10 <br />a <br />E <br />0 +'_ <br />1/1/93 <br />1 / 1 /94 1 / 1 /95 1 / 1 /96 12131 /96 12/31!97 12/31 /96 12/31 /99 12/30/00 <br />Figure 2. Gunnison River Temperatures Above and Below the Aspinall Unit <br />Reservoirs. <br />CSU <br />Hydrosphere Resource Consultants <br />