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<br />effects of the increased salt discharge during the next 20 years may far <br />outweigh the effect of the reductions experienced beyond this 20-year time <br />frame. A demonstration ground-water flushing program is currently being <br />performed to determine if this alternate would be a more practical method <br />of addressing long-term salt load contributions from the study area. <br /> <br />Installation of a tile drainage system may intercept leaching water, <br />preventing it from flowing through the ground-water aquifer. This drain <br />effluent could potentially be utilized as a source of powerplant cooling <br />water. This plan component has not been evaluated as a part of the <br />studies conducted to date. <br /> <br />Based on these components, three alternatives are currently being evaluated <br />by Reclamation, They are: (1) a combination of IMS and onfarm improve- <br />ments which would result in a 60 percent irrigation efficiency, (2) a <br />lateral lining program, and (3) a combination of alternatives 1 and 2. <br /> <br />The costs shown in the subsequent section of this report for these alterna- <br />tives were developed by Reclamation. Development of the total salinity <br />control program would involve a joint effort with SCS, Each agency is <br />cooperating in the basinwide salinity reduction effort. Onfarm program <br />improvements would be provided to the farmer on a cost-shared basis. <br />Reclamation would monitor the salt loading mechanism and provide initial <br />irrigation management services. <br /> <br />A no project alternative, required to evaluate the other alternatives and <br />wildlife plans, will be developed as a part of future studies. <br /> <br />The PVID would continue to maintain and operate the system using equipment <br />that would be purchased as a part of constructing the unit, if necessary. <br />An operation, maintenance, and replacement contract similar to that with <br />the Grand Valley Water Users Association for the Grand Valley Unit would <br />be negotiated for the Palo Verde subarea and signed before construction <br />begins. The contract will assure that saved water will be used in the <br />project area only if such use will not impair the reductions in salinity <br />concentrations that are projected to accrue to the Colorado River at <br />Imperial Dam as a result of the Palo Verde Irrigation District Project. <br />Water conservation on presently irrigated land will be encouraged. The <br />saved water would be used as part of the water supply for the PVID's <br />proposed low-head hydroelectric generation powerplant. <br /> <br />Estimated Costs and Effectiveness <br /> <br />Investment costs of the Palo Verde Irrigation District Unit include Federal <br />expenditures for construction and interest during construction for the Palo <br />Verde subarea. These costs are based on appraisal level designs and estimates <br />and January 1981 prices. A summary of estimated costs is presented below: <br /> <br />C~2939 <br /> <br />13 <br />