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<br />A cooperative River Basin study has been completed by USDA on the Colorado <br />N River Indian Reservation (CRIR) . Several alternative plans have been <br />~"" fOI'lllUlated that conserve water on existing irrigated lands and allow full <br />to.... resource development on the Reservation; Data available, from this study <br />~ supports the hypothesis that there is a minimal amount of salt pick up on the <br />CRIR. Another conclusion that could be dr,awn from the study is that long-term <br />benefits of better irrigation systems ,and practices ,appear, to haveea <br />relativelY SJII8ll effect on downstream salinity. ,ThefinaLUSDAreport on this <br />study will be published in FY-85. <br /> <br />,B. IMPLEMENTATION <br /> <br />,Prior to pa~sage of PL-98-569, Public Law 93-320 directed tbe secretary of <br />,Ar;ricultureto construct onfarm irrigation systems under 9rog,rams available to <br />that deparbllent. USDA implementation programs are being' carri.ed out in Grand <br />Valley, Colorado and Uinta ,Basin, Utah under current. USDA programs. <br /> <br />GRAND,VALLEY <br /> <br />IrriRation system I1IlI>rovements. The method of irrigation'used almost , <br />exclusively in the valley is furrow irrigation. Irrigation'slopes usually <br />exceed one percent,and .soils have low water intake rates. Fields average <br />about 10 acres in size. Existing earthen irrigation ditches are being <br />replaced with concrete lined ditches, gated pipe, or ,underground pipelines. , <br />Some concrete' ditches are constructed with a ported outlet for, each furrow and <br />"accommo~ate tlmedcontrol, gates fOr semi-automatedirrigat~on. However, gated <br />pipe is becoming a popular and less expensive alternative to ported concrete <br />ditches. <br /> <br />Some gated pipe is being fitted with cablegation controls,as another type of <br />semi-automation. Cablegation'is the name given to the system where water <br />pressure pushes a movable plug through gated pipe laid across ,the head of a <br />field,~eplug's rate of movement, is restrained by a cable or' other cord, <br />hence the nainecablegation. Water flowing through the , gated pipe is , ' <br />disCharged into the furrows through a limited number of gates in the,pipe <br />depending on flow rate and slope of the pipe. The flow througJl each gate <br />varies from a maximum rate immediately behind the plug,to no flow at some <br />distance back from the plug. At any given gate the initial high flow rate <br />enables water to reach the end of the, furrow in the shortest possible time. <br />The gradUal decrease inflow permits water to percolate into~the ,ground While <br />minimizing runoff 'from the end of the furrow. Users, of this irrigation method <br />report 30 to 50 percent savings in t.ime and water use While adequately . <br />irrigating the field. Because of these and other benefits cablegation,is <br />being accepted by farmers as a,method of irrigation. <br /> <br />-17- <br />