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<br />are needed to enhance irrigation automation capability. The Moapa Indians <br />have requested assistance from Clark County Conservation District to redesign <br />the system serving their fields (about 600 acres). The present conservation <br />district program will require acceleration to meet technical assistance demands. <br />Accelerated cost-share assistance is needed to accomplish downstream annual <br />salt load reduction from off-farm improvements. <br /> <br />In Lower Moapa Valley replacement of the open canal delivery system <br />with pipelines would facilitate automation and allow application of water <br />to more accurately meet actual crop needs. Cost-share assistance is <br />recommended to accomplish installation due to insufficient onfarm benefits <br />and a current high level of indebtedness by the irrigation company. Such <br />financial assistance is justified by downstream salinity reduction benefits. <br /> <br />N~eded repairs to the Muddy Valley Irrigation Company's distribution <br />system include: 1.420 feet of lining of earth ditch. repair of 16.020 feet <br />of concrete ditch. 1 diversion box. 100 feet of 24 inch corrugated metal <br />pipe. and 100 feet of corrugated mata1 pipe for a flume. If the existing <br />system was replaced with a pipeline system about 25 percent of the system <br />would be relocated. <br /> <br />Erosion control would provide downstream salinity benefits. Onfarm <br />water management would also reduce erosion. Acceleration of present SCS <br />programs and cost-share assistance would be needed. There is a need <br />for reducing erosion on 10 bank miles of channel in Lower Valley and for <br />erosion control at road crossings and waste water inlets in both valleys. <br /> <br />Problems and Needs Associated With Erosion and Sedimentation <br /> <br />Erosion. sediment and consequent salt loading. both from natural and <br />man-induced sources cause land and water quality problems. Sediment and <br />salt loading problems occur on cropland. rangeland. pasture1and and in <br />urbanized areas. <br /> <br />Average annual sheet. rill and gully erosion varies from less than one <br />to greater than ten tons-per-acre-per-year. (See Figure 10 - Erosion Areas). <br />Ten percent of the stream channel has erosion in excess of 1.000 tons per <br />mile. Sheet and rill erosion account for 20-30 percent of the sediment <br />yield. Erosion of gullies. washes. streambanks and channel bottoms account <br />for the other 70 to 80 percent of sediment yield. Estimated sediment yield <br />from Muddy River averages 385.000 tons annually. The estimated salt loading <br />resulting from erosion averages 10.000 tons annually. <br /> <br />Most of the sediment load is derived from rangeland areas. However. <br />a land treatment program in rangeland areas is not economically feasible. <br />Improved irrigation water management would reduce erosion on crop and <br />pasture lands and provide a minor sediment yield reduction. Treatment of <br />channel banks would significantly reduce average annual sediment yield. <br /> <br />C\n0~.O <br />l~{~ <br /> <br />30 <br />