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<br />I <br />I <br />I <br />I <br />I <br />i <br />I <br />I <br />I <br />I <br />II <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />il <br /> <br />SUMMARY <br /> <br />The Muddy River flows through Moapa Valley into Lake Mead. upper <br />Moapa Valley and Lower Moapa Valley are divided by the "Narrows" <br />downstream of Glendale. Meadow Valley Wash also flows through <br />upper Moapa Valley and enters Muddy River near Glendale. The <br />amount of irrigated land in Moapa Valley has been decreasing and <br />is approximately 4,860 acres with 2,170 in the Upper Valley and <br />2,690 in the Lower Valley. <br /> <br />The Muddy River presently contributes an average of 56,500 tons <br />of salt and 385,000 tons of sediment to Lake Mead each year. A <br />reduction of 18,700 tons of salt can be accomplished in the Moapa <br />Valley by: (1) replacing the irrigation delivery system in Lower <br />Moapa Valley with a pipeline to eliminate canal seepage and allow <br />implementing a modified demand delivery system and (2) increasing <br />onfarm irrigation efficiency from 54 to 66 percent in the future <br />by improving onfarm systems and management on about 3,000 acres <br />in the study area. <br /> <br />The existing condition was evaluated and two levels of future <br />salt yield were analyzed in detail: Alternative 1 (Future <br />without a Salinity Project) and Alternative 5. Four other <br />alternatives are also discussed. All alternatives were <br />contrasted to the future condition without a project. <br /> <br />Implementation of the recommended plan (Alternative 5) onfarm <br />will consist primarily of laser controlled land leveling, <br />subsurface pipelines with risers and valves, and gated pipe, To <br />achieve the required level of irrigation water management, semi- <br />automated irrigation systems will be installed onfarm. These <br />systems will control timing of irrigations and the length of time <br />water is applied to fields based on input from weather stations <br />and soil monitoring stations. A public awareness and information <br />program will be implemented and demonstration and field <br />evaluations conducted to educate all irrigators on irrigation <br />water management concepts. Training will be provided in the <br />operation of new devices and systems. The Irrigation company <br />will also provide training and assistance in operating the new <br />systems. <br /> <br />Total onfarm implementation will cost $1,900,000. The present <br />annual operation and maintenance cost would remain at about <br />$20,000. Additional maintenance costs will be needed for the <br />automated systems but will be offset by reduced labor costs. <br /> <br />A pipeline distribution system in Lower Moapa Valley is <br />necessary to facilitate improvements in onfarm irrigation <br />systems. A closed pipeline system allows more flexibility in <br />water deliveries to better match crop needs and allows better <br />management of water without bypassing excess flows. The cost of <br />the off-farm distribution system is estimated to be $5,000,000. <br />presently, about $70,000 is spent annually for operation and <br />maintenance of the deteriorated concrete lined open ditch system. <br /> <br />0031Jl <br /> <br />ii <br />