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<br />,:::> <br />r..... <br />'.:;'; <br />~ SUMMARY <br />C) <br /> <br />2 This report contains the results of evaluations by the Soil Conservation <br /> <br />3 Service on 4,620 acres (7 percent sample) of irrigated cropland in the <br /> <br />4 west end of Grand Valley, and the extrapolation of these results over <br /> <br />5 the entire valley. Present irrigation practices were evaluated to <br /> <br />6 establish existing conditions as a basis for recommending on-farm <br /> <br />7 improvements and to measure effects of the improvements. <br /> <br />8 Four program alternatives were evaluated. Alternative one cunsidered an <br /> <br />9 improvement in irrigation management by changing the time of set and <br /> <br />10 some system improvements; the second considered more extensive improve- <br /> <br />11 ments in existing systems and management of the time of set and flow <br /> <br />12 rates; the third, the same as alternative 2, considered changing 5,000 <br /> <br />13 acres to drip or sprinkler methods of irrigation and management practices <br /> <br />14 including cut-back flow rates; and the fourth program alternative level <br /> <br />15 of on-farm irrigation improvement is a combination of the other alternatives. <br /> <br />16 The annual salt load pickup attributed to on-farm irrigation is estimated <br /> <br />17 to be 360,000 tons while upland erosion contributes another 80,000 tons <br /> <br />18 accounting for 440,000 tons of the annual salt load increase from Grand <br /> <br />19 Valley in the Colorado River. The Bureau of Reclamation has estimated <br /> <br />20 an additional 350,000 tons per year of salt pickup due to seepage from <br /> <br />21 off-farm canals and laterals in the valley. <br /> <br />22 The program alternatives contained in this draft report have not yet <br /> <br />23 been discussed with the local people so they can indicate a preference. <br /> <br />2 <br />