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<br />Alternative 1 <br /> <br />Alternative 1 would use existing canal and lateral systems with major <br />repairs and improve the onfarm irrigation systems and erosion control. This <br />is the alternative having a minimum of structural works. <br /> <br />This alternative would improve irrigation efficiency and reduce salt <br />loading by improved water scheduling and control of water applied to irri- <br />gated fields. Changes to the onfarm irrigation systems would be minimal. <br />Seasonal gross application would be smaller, thus reducing runoff and deep <br />percolation. See Table 8. <br /> <br />The replacement of sections of the deteriorated water delivery system <br />in Lower Moapa Valley and repair of deteriorated sections in the Upper Valley <br />are proposed. This work would reduce canal seepage. The condition of other <br />components of the irrigation system is satisfactory. Its design and con- <br />struction are credits to those irrigation pioneers responsible for its <br />deve 1 opment. <br /> <br />Bowman Reservoir provides supplemental water. Periodic dredging and <br />other routine maintenance are necessary. The Bureau of Reclamation reported <br />in 1971 the structure condition as adequate. The safety of the structure <br />was confirmed by U.S. Army Corps of Engineers under the National Dam Inspect- <br />ion Act. The structure was enlarged in 1967-1968 by the Muddy Valley <br />Irrigation Company under professional engineering supervision. Limited seep- <br />age occurs below the structure. ' <br /> <br />Improved water scheduling will require equipment to measure soil mois- <br />ture, salinity of irrigation water, and quantities of water delivered. In <br />addition, water delivery schedules on a more flexible basis than the present <br />rotation system should be developed. Programmable calculating equipment is <br />recommended for this alternative. A telemetry system is recommended to <br />support the water delivery scheduling. Water scheduling is complicated by <br />limited storage for supplemental water. <br /> <br />Automation (or semiautomation) of onfarm systems is needed to control <br />short irrigation set times (length of time water is applied to fields). <br />Many of the irrigators work at nonfarm jobs. Additional labor costs would <br />be incurred to manually operate with shorter set times. Onfarm automation <br />reduces labor about 18,000 hours or $72,000 on an average annual basis. <br />Telemetry associated with data input would include monitoring of automated <br />(and/or semi automated) onfarm irrigation systems. Monitoring would alert <br />managers of automation failure so that repairs could be made as soon as <br />pOSSible. <br /> <br />Irrigators are assumed to obtain the same level of water management, <br />but onfarm irrigation effi~encies would vary depending on soil type, length <br />of run, irrigation head, slope, etc. Irrigation efficiency is expected to <br />average 55 percent. Water management data are summarized in Table 8. <br /> <br />(', ,', 1)7 ~ <br />~. !.' ... J. 9 <br /> <br />39 <br />