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<br />of the top of the less permeable Bouse Formation, although most of the <br />flushing occurs at shallower aquifer depths. <br /> <br />Salt discharge is expected to gradually decline until the <br />gone, a process that will take well over a hundred years. <br />of the salt may be gone within 60 years. <br /> <br />excess salt is <br />At best, most <br /> <br />A 1 ternat ives <br /> <br />The following components were considered in developing alternatives for <br />further study: <br /> <br />Irrigation management services <br />Onfarm improvements <br />Latera 1 1 i ni ng <br />Ground-water flushing <br />Tile drain system <br /> <br />The lateral lining alternative component proposes lining 20 miles of <br />laterals. It was assumed that water service would be maintained throughout <br />the year, and that reaches of large laterals would be lined in i-mile <br />increments to avoid construction of temporary road crossings. A temporary <br />parallel ditch, including structures and turnouts to provide water service, <br />would be constructed adjacent to the existing lateral section. Water <br />would then be diverted into the temporary facility, and earthwork would <br />begin on the permanent facility. The existing lateral would be partially <br />backfilled and trimmed to the required shape of the lined section, which <br />could have a smaller cross-sectional area than the existing unlined <br />section. Existing check and farm turnout structures would be utilized to <br />the extent practicable. <br /> <br />The IMS (Irrigation Management Services) program involves greater precision <br />in irrigation scheduling so the amount of water applied during each <br />irrigation is matched to the needs of the crop, the character of the soil, <br />and the leaching requirements for Colorado River water. Facilities needed <br />for this program are an office building and equipment. An agricultural <br />research program and an education program on irrigation efficiency would <br />be designed to provide water users the information to induce better water <br />management, <br /> <br />An onfarm program is another component necessary to improve irrigation <br />efficiency. Onfarm improvements would consist of lining farm ditches, <br />installing metered farm turnouts, land leveling, and constructinq additional <br />farm ditches where needed. <br /> <br />An alternative involving accelerated flushing of salt from the subarea for <br />the first 20 years by liberal application of water, followed by achievement <br />of 60 percent onfarm irrigation efficiency, was also considered. This <br />concept was based on the possibility of surplus flows in the Colorado <br />River during the next decade. Such a measure would result in a reduction <br />of salt discharged 20 years in the future and beyond. However, the <br /> <br />12 <br /> <br />r; '-I ., 8 <br />....:/v <br />