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<br />'':'> <br />w <br />....-;! <br />) <br /> <br />SUMMARY SHEET <br />Grand Valley Unit <br />Colorado River Basin Salinity Control Project <br /> <br />August 1985 <br />Page 1 of 2 <br /> <br /> <br />~ <br /> <br />,-' <br /> <br />LOCATION <br /> <br />The Grand Valley Unit. -located in west-central <br />Colorado along the reach of the Colorado River <br />between the towns of Palisade and Mack. includes <br />Grand Junction. the largest city in western <br />Colorado. The hatched portion of the map shows the <br />Stage One area. The Stage Two area is the <br />remainder of the valley outside of the Stage One <br />area. <br /> <br />AUTHORITY <br /> <br />The Grand Valley Unit. a component of the Colorado <br />River Basin Salinity Control Project, was autho- <br />rized for construction by the Colorado River Basin <br />Salinity Control Ac~ of 1974 (Public Law 93-320). <br />Public Law 98-569, enacted on October 3D, 1984, <br />amended Title II provisions of that act. <br /> <br />PURPOSE <br /> <br />The purpose of the Grand Valley Unit is to reduce <br />the estimated 580,000 tons of salt added to the <br />Colorado River annually from the unit area as a <br />result of conveyance system seepage and agri- <br />cultural practices. <br /> <br />OVERALL PLAN <br /> <br />Studies for the overall unit indicate that the salt <br />loading of the Colorado River in the Grand Valley <br />occurs from conveyance system seepage and irrigation <br />return flows moving as water passes through highly <br />saline soils and the underlying Mancos Formation <br />shale. By reducing the amount of ground water <br />percolating into these saline soils, salt loading to <br />the Colorado River would be reduced. This reduced <br />sal t load would decrease the salinity of the river <br />at Imperial Dam, the last lIajor diversion point of <br />the Colorado River in the United States. <br /> <br />A conveyance systems improvement program is being <br />conducted by Reclamation to determine and implement <br />a cost-effective method of reducing off-farm seepage <br />and salt loading. On-farm improvements, including <br />upgrading irrigation systems through cost assistance <br />and improving irrigation management to reduce deep <br />percolation from farm oper,ltions, are being studied <br />and implemented by the Soil Conservation Service. <br /> <br />The systems improvement program is being implemented <br />in stages. This allowed the Bureau of Reclamation <br />to begin construction in a portion of the valley <br />where plans and designs were complete and where <br />sufficient data are available to assess the impac t s <br />of initial development. <br /> <br />No <br /> <br />L <br /> <br />. <br />, <br /> <br />C0/101 <br /> <br />I~ALJSAOE . <br /> <br />, <br />