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Stream gains were calculated for the two reaches between the lower three gaging <br />stations by subtracting the actual gaged or measured inflows into the reach from the actual <br />gaged or measured outflows in the reach. When evaluated this way, the stream gains included <br />any releases of storage water that were made to the Big Thompson River. The releases of <br />water to the Big Thompson River through the Powerplant and Wasteway were treated as inflows <br />in these calculations and thus were excluded from the stream gains. The stream gains were <br />assumed to occur below the mouth of Buckhorn Creek, and otherwise distributed according to <br />reach lengths. The necessary daily flow and diversion data were obtained from the CDSS with <br />some supplemental data from the USBR and USGS records. <br />Figure 4 illustrates the calculation of the divertible native flow for May 6, 1997. Some of <br />the ditches on the Big Thompson River are shown as being supplied through single points of <br />diversion in the figure to simplify the illustration. All the ditches are treated individually in the <br />calculations, however, unless they actually share a point of diversion with another ditch. <br />Appendix A is a monthly summary of these daily calculations. <br />The divertible flows for some days in the period appeared to be anomalous, most likely <br />' occurring as the result of inaccurate data or imprecise operation and administration. In addition, <br />diversions on some isolated days of divertible flow were judged to be impractical and were <br />excluded from the analysis. In general, the volumes of water involved in these days were small, <br />' and their elimination tends to understate the divertible flows. <br />' Table 7 shows the results of these calculations. The divertible flows averaged 25,041 <br />acre -feet annually and ranged from none in two years of the period to almost 116,000 acre -feet <br />' in 1983. <br />The portion of this excess native water that could have been diverted into the Olympus <br />' Tunnel was determined in the next step in the calculations. Initially, the native water that <br />occurred at Olympus Dam was calculated by (1) adding the diversions into the Olympus Tunnel <br />to the gaged flow in the Big Thompson River below Olympus Dam, (2) subtracting the Adams <br />' Tunnel diversions, and (3) adjusting for any changes in storage in Marys Lake and Lake Estes. <br />The potential diversions at this location were then limited for the minimum instream flow <br />bypasses at Olympus Dam and the 550 -cfs carrying capacity of the Estes Park - Foothills Power <br />system. Table 8 shows the results of the calculations: the native water that could have been <br />diverted into the Olympus Tunnel averaged 14,912 acre -feet annually. <br />' The additional portion of this excess native water that could have been diverted into the <br />Dille Tunnel was then determined. This was divertible native water that was available but could <br />not be taken into the Olympus Tunnel because of its minimum instream flow bypasses and <br />tunnel capacity. It was limited to a maximum Dille Tunnel diversion capacity of 400 cfs and a <br />maximum combined diversion capacity of 950 cfs for both the Olympus and Dille Tunnels. This <br />combined diversion capacity is based on 400 cfs for the pumping capacity into Carter Lake and <br />' 11 <br />