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<br />,.' ,- <br />Uv'; . <br /> <br />')'" <br />~. '") <br /> <br />Specific practices employed to reduce irrigation diversions generally reduce both non- <br />productive consumptive use and the return flow component of the irrigation water budget. <br />i <br />Certain measures can have a larger impact on reducing incidental consumptive use than <br />others. Among those that reduce ditch evaporation are combining parallel ditches and <br />replacing ditches With closed conduits, such as pipes. Reservoir operations can be varied <br />to also reduce evaporation. Field evaporation can be reduced by sprinkler application, <br />trickle irrigation, land leveling, and surge irrigation. These metbods get water into the crop <br />root zone faster than traditional flood irrigation methods, thereby reducing evaporation and <br />surface runoff. Phreatophyte consumptive use can be reduced or eliminated by clearing and <br />cutting, or ditch lining which limits seepage into the root zone of non-cropped areas. <br />Irrigation management, which involves the closer timing of irrigation deliveries to soil <br />moisture content and crop needs, is also capable of reducing field evaporation and <br />phreatophyte growth. <br /> <br />Non consumptive losses are best reduced by ditch lining on-farm practices which reduce <br />seepage and thereby deep percolation to tributary aquifers. Reuse of tail water from pump <br />back pits can reduce diversions and impact return flows. All of the methods capable of <br />reducing consumptive losses also impact deep percolation and return flows to some extent. <br /> <br />The water budgets previously examined (Figures 2A, 2B, and Table 1) represent the <br />before and after conditions for an area in Utah where irrigation improvements are proposed <br />under the federal salinity control program. The improvements for this area will mainly <br />consist of replacing flood irrigation practices With sprinkler systems. Some minor ditch <br />lining Will also be provided. This area historically has experienced short supplies due to its <br />junior water rights, and consumptive use (but not irrigated acres) will actually increase after <br />the improvements are installed. The example demonstrates the relative magnitude of the <br />changes in non-productive consumptive use and return flows before and after a salinity <br />project. <br /> <br />9 <br />