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<br />Re9ional Forester 4 <br />Step 1. Pre1ililinary Estimates of llater Values. <br /> (a) ~9ri cultura I: <br /> Start $ CPI 1982 <br /> Or. White (1978) 7.00 1.35 9.46 <br /> RPA (1/1982) 45.50 1.04 47.34 <br /> Irrigation Study (1980 ) 55.50 1.12 62.28 <br /> (b) Municipal and Industrial: <br /> Start $ CPI 1982 <br /> Dr. White (1978) 96.00 1.48 142.00 <br /> RPA (1/1982) 205.00 1.06 218.00 <br /> Wyoming 302.00 1.06 320.00 <br /> Colorado 199.00 1.06 211.00 <br /> South Dakota 205.00 1.06 218.0u <br />Step 2. Adjustment for Evaporation loss. <br /> <br />Exhibit 2 briefly indicates Dr. White's adjustments for evaporation, <br />which ranged fror.! 0.6 percent in the Colorado-Gunnison Basin to over 40 <br />perct'nt in the lippeI' Arkansas Basin. These .adjustments were used in a <br />way that reduced the value of water produced on the watershed. <br /> <br />Three conrnents are in order about the procedure itself: <br />1. The method of calculation computes an average evaporation loss over <br />the whole water development system. It does not calculate the <br />evaporation loss for the incremental water yield under analysis. <br /> <br />If we assume, as does Or. White, that water yield increases will be <br />stored in large reservoirs, then the evaporation amounts will be <br />less than five perce;lt and probably more like two or three percent. <br />See ET.hibit 2 for the relationships. <br /> <br />2. The RPA evaluation credits the Forest Service with 100 percent of <br />the water yield increase value. This appears to suggest that <br />ev~poration loss was not incorporatfd into the analysis at all. <br /> <br />3. No adjustments for evaporation arenlade in the updated water values. <br /> <br />step 3:- -AdJlJstme'nffor-Re'::use-andR-etu"rnFfciw: __u_ __m <br /> <br />Exhibit 3 briefly indicates Or. White's adjustment for return flows or <br />re-use of "ateI'. In some cases, the adjustment tripled the water benefit <br />value. <br /> <br />Since the adjustment h highly sensitive to the return flow percentage, <br />the determination of return flow is critical to good values. <br /> <br />~:,16 <br />