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<br />was followed by a drop in ground water levels, which is a good indicator of <br />reduced saline ground water inflow to the Wash. A long term reduction of <br />7,000 tons per year is expected. <br /> <br />The ground water flow reduction strategy is being studied by the Whitney <br />~ Verification Program. A ground water detention basin (formed by a peripheral <br />OQ slurry trench/wall) would be constructed near the historic community of <br />~ Whitney. The detention of ground water upstream of the wall is expected to <br />~ reduce the deep percolation of less saline surface water. <br /> <br />The completion of the Pittman and Whitney Verification Programs is <br />expected near the end of 1989. The information learned from these programs <br />would then be used to develop a salinity control plan that will have local <br />support. <br /> <br />9. Lower Gunnison Basin Unit (Reclamation and USDA) <br /> <br />The Lower Gunnison Basin Unit is located in the Uncompahgre Valley <br />in west-central Colorado. The study area consists of lands irrigated by the <br />Uncompahgre Project along the lower reaches of the Uncompahgre River in Delta <br />and Montrose Counties. The area which encompasses the communities of Delta, <br />Montrose, and Olathe is principally agricultural, and agribusiness is of <br />primary importance to the local economy. <br /> <br />An estimated 360,000 tons of salt are picked up in the study area <br />annually and conveyed to the uncompahgre, Gunnison, and Colorado Rivers. The <br />salt pickup is a result of deep percolation and conveyance system seepage as <br />water passes through the weathered and fractured shale of the Mancos Formation <br />on its way to drains and the uncompahgre River. The primary salt contributed <br />by this formation is gypsum (calcium sulfate). <br /> <br />The recommended plan of development for the Lower Gunnison Basin <br />Unit consists of (1) elimination of winter water flows in the irrigation <br />system with replacement through the domestic water delivery system and (2) <br />concrete lining five separate Uncompahgre Project canal systems east of the <br />uncompahgre River. <br /> <br />The winter water replacement program would eliminate seepage from <br />canals and laterals during the winter months. At the same time, it would <br />allow more efficient livestock watering during winter with no resultant <br />salinity impacts. The program could reduce annual salt loading from the study <br />area by about 80,000 tons. Advance planning on the winter water replacement <br />program is expected to be completed in 1987. Because the lining of the canals <br />and laterals is less cost effective than other salinity control measures in <br />other units, advance planning on this portion of the plan will be conducted <br />after more cost-effective measures have been implemented. <br /> <br />CUrrent activities include development of design and cost estimate <br />information for the expansion of the domestic water systems. Water users who <br />use winter stock water have been identified through a pre-application form <br />sponsored by the uncompahgre Valley Water Users Association. <br /> <br />The SCS on-farm report completed in September 1981 outlines an <br />implementation plan that is compatible with the Reclamation plan. Four <br />cost-effective subareas have been identified for high priority implementation. <br /> <br />VII-19 <br />