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Linda J. Bassi April 29, 2008 <br />Page 6 <br />1.2 <br />Dry Normal Conditions Wet Conditions <br />1 <br />0 <br />. <br />0 <br />8 <br />. <br />6 <br />0 <br />. <br />3 <br />0 <br /> <br />0 <br />4 <br />. <br />0 <br />2 <br />. <br />0 <br />0 <br />. <br />0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 <br />Probability <br />Figure 4. Distribution of Reconstructed Flows in Two Elk Creek from 11115 through 12131 <br />(based upon 1964-2005 period of record). <br />Table 1 provides a summary of the potential impacts on the flows in Two Elk Creek <br />under dry, average and wet year runoff conditions with a pumping rate of 15 gpm for 10 <br />hours per day, assuming that each pumping period would be followed by 14 hours with <br />no pumping. <br />Table 1. Potential Flow Reductions in Two Elk Creek <br />with 10-hour intermittent pumping <br /> <br />Runoff Natural <br />Flow Well Pumping Impact <br />(cfs) Instream Flow Impact <br />Conditions (cfs) Max Min Max Min <br />Dry 0.46 0.019 0.009 4.1 % 2.0% <br />Average 0.61 0.019 0.009 3.1 % 1.5% <br />Wet 0.74 0.019 0.009 2.6% 1.2% <br />The use of alternating pumping and recovery periods would effectively buffer the impact <br />of well pumping on streamflows by reducing streamflow depletions to about 57% of the <br />actual pumping rate. <br />It is important to note that the hydrologic analysis detailed above is based upon <br />estimated flows in Two Elk Creek at the upper terminus of the CWCB - ISF reach. The <br />4 cfs ISF water right for Two Elk Creek is based upon a stream cross section and flow <br />analysis on Two Elk Creek at a location 150 yards upstream of the confluence with the <br />AMEC Earth and Environmental, Inc. <br />