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\ I SUMMARY The Regional Director's proposed feasibility report for the Lower Gunnison Basin Unit of the Colorado River Water Quality Improvement Program (CRWQIP) is scheduled for completion later in 1981. Until then, this status report will inform concerned interests of the costs and impacts associated with the recommended plan. Yne Lower Gunnison Basin Unit investigation in west-central Colorado, which includes lands of the Uncompahgre Reclamation Project, was authorized by Public Laws 93-320 and 96-375 to determine the most cost-effective way to reduce the salinity in the Colorado River system by reducing the quantity 0 f poor quality water entering the Uncompahgre River. The. Uncompahgre River, which carries over 364,000 tons of salt from the study area, flows into the Gunnison River which, in turn, flows into the Colorado River. The salt is picked up from both off-farm and on-farm sources and results in an increase in salinity at Imperial Dam of about 37 milligrams per liter (mg/L). The Soil Conservation Service (SCS) and the Bureau of Reclamation are coordinating individual studies in the total salinity reduction effort. Most of the Uncompahgre Project irrigation facilities were construc- ted before 1915 and much of the system was cut directly into the,saline soils and rock. Conveyance system seepage through the unlined canals results in a loss of water and the aforementioned salt loading. A proposed Uncompahgre Project Rehabilitation and Betterment (R&B) Program has been coordinate> with the salinity control investigation; the programs would supplement one another. Following in1t1ation of this study 1n 1976, a strong public involve- ment program aided in formulating and evaluating a number of alternatives. In September l~ 79, public participants recommended a plan to concrete line as much of the canal and lateral system in the Uncompahgre Valley as can be Justified under the salinity reduction objective. Where field conditions warrant, flexible lining would be considered if concrete lining is deter- mined to be technically infeasible. The recommended plan will be revised as the feasibility study progresses. The recommended plan calls for lining a total of about 254 m1les of canalS and laterals, Which wouid reduce the salinity concentration at Imperial Dam by about 15.2 mg/L. With implementation of the recommended plan, all water rights would be retained by the Uncompahgre Valley Water Users Association, the administering agency for the Uncompahgre Project. Lands served after project construction would be limited to those acreages already under irrigation by the water users. Contracts executed prior to the initiation of construction would require the Association to assume all obligations regarding the accomplishment of maxim~~ reduction of salinity inflow to the Colorado River. 1 (J~(!~"