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<br />(3) An annual reduction of between 400,000 and 500,000 tons of salt into <br />drain water results from the reduction of about 100,000 acre feet or <br />return flo~. The reduction in amount of return flow is due, in mast <br />part, to the reduction in deep percolation water below the root <br />system of crops on the cropland. The tons of salt are based on the <br />drain ~ater concentration of about 3700 milligrams per liter of salt <br />which is about 5 tons per acre foot of return flow. The <br />concentration of salt, 3700 mg/I, is projected to remain about the <br />same in the forseeable future. As shown on the Return flow chart, <br />return flow was reduced by about 100,000 acre feet annually. <br /> <br />The desalting plant near Yuma, Arizona, will treat the remaining <br />return flow and use the product water. The desalting plant at the <br />present time is designed to treat about 67,000 acre feet of drain <br />water annually. The capital cost to install is about 215 million <br />dollars and the annual operation, maintenance, and replacement is <br />considered to be about 22 million dollars. This was taken from an <br />unpublished document titled, "Yuma Desalting Plant - A Water Quality <br />Solution" by K. M. Tro~peter about September 1987. <br /> <br />(4) Positive changes were made in irrigation labor, ditch capacity and <br />kind and number of field turnouts, as well as in efficiency of <br />irrigation ~ater use. <br /> <br />(5) The project claims national and international attention as we <br />learned and were able to explain experiences such as: <br /> <br />--systems designed to irrigate fields faster and spread vater more <br />uniformly <br /> <br />--use of larger outlet structure with energy dissipators to control <br />large flows of water <br /> <br />--demonstrated the use of conservation planning process in the <br />development of contracts <br /> <br />--social change was necessary to accept the fact that deep <br />percolation water had to be reduced to meet the goal of the salinity <br />control project. Three main options were considered: (I) do <br />nothing, (2) abandon irrigation and (3) accept the cost-share <br />program and reduce deep percolation. (The third alternative was <br />selected quickly). <br /> <br />--the people and the SCS made the program work even though <br />traditional and old habits had to be changed. <br /> <br />During the eleven years of the project, planning and application continued at <br />an acceptable rate. <br /> <br />Planning and development of contracts throughout the length of the project <br />resulted in resource management systems on over 48,195 acres. <br /> <br />On each acre in contracts, soil, water and plant management practices were <br />used. These include conservation cropping sequence, crop residue use and <br />irrigation water management. <br /> <br />- 15 - <br />