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runoff. Collectively, these problems <br />have resulted in increased salinity <br />problems by leaching salts into the <br />river system. Approximately <br />1 million acres are irrigated in <br />17 identified irrigation salt source <br />areas in the Colorado River Basin. <br />SCS estimates onfarm water <br />management and salinity control <br />measures would be cost effective on <br />over 600,000 acres in 11 different <br />salt source areas. <br />Irrigation Salt Source <br />Studies <br />The SCS conducts the salinity <br />control studies of irrigation salt <br />source areas in the Basin. These <br />studies have been done under the <br />River Basin Studies authority of <br />Public Law 83-566. The studies <br />evaluate the magnitude of salt <br />loadings, the treatment and <br />management alternatives for <br />salinity control, and estimated <br />project implementation costs. <br />Working in cooperation with <br />Reclamation, other Federal agencies, <br />and concerned state agencies, USDA <br />has completed eight major studies <br />to date - Grand Valley, Colorado; <br />Uinta Basin, Utah; Big Sandy, <br />Wyoming; Moapa Valley, Nevada; <br />Virgin Valley, Nevada and Arizona; <br />and Lower Gunnison, McElmo <br />Creek, and Mancos Valley, <br />Colorado. A joint study is <br />underway with Reclamation in the <br />Price-San Rafael Rivers Unit, Utah. <br />Four other areas have been <br />investigated: two were suspended <br />and two had no recommended <br />plans. <br />Project Implementation <br />Four USDA Colorado River <br />salinity control projects are under <br />implementation: the Grand Valley, <br />Colorado (initiated 1979); Uinta <br />Basin, Utah (initiated 1980); and the <br />Big Sandy, Wyoming, and Lower <br />Gunnison, Colorado, (initiated in <br />1988). These projects focus on the <br />application of salinity control <br />practices to improve onfarm <br />irrigation water management and <br />related lateral delivery systems to <br />reduce deep percolation and salt <br />loading. Other USDA projects are <br />scheduled for future implementa- <br />tion. The status of these projects is <br />shown in the listing of all salinity <br />control projects in this publication. <br />Under the USDA Colorado <br />River Salinity Control Program <br />participants, with technical <br />assistance from SCS, plan, install, <br />and maintain salinity reduction <br />practices including replacement of <br />fish and wildlife values foregone. <br />Dirt ditch onfarm is being concrete <br />lined to stop water loss and seepage.