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with a maximum diversion of 717,148 acre-feet. Irrigation return flows are collected in a 100-mile drainage system and returned to the river. An investigation was made to find a way to reduce the salt loading to the Colorado River from irrigation on the reservation. Studies indicated the Reservation is not a contributor of salt to the river. A concluding report was released in October 1979. Lower Gunnison Basin Unit, Colorado The Lower Gunnison Basin Unit is in west-central Colorado in the Lower Gunnison River Basin of Delta and Montrose Counties. The Stage I area under study is the Uncompahgre Valley. The Stage II area to be studied later is centered around Hotchkiss. The Uncompahgre River carries over 360,000 tons of salt from the study area and flows into the Gunnison River, which in turn flows into the Colorado River. The salt picked up from seepage resulting from conveyance of water through unlined canals and laterals, onfarm sources, and seepage resulting from conveyance of winter water results in an increase in salin- ity at Imperial Dam of about 36 mg/L. SCS and Reclamation are coordinating individual studies in the total salinity reduction effort. The recommended plan calls for lining a total of about 254 miles of canals and laterals, which would reduce the salt loading by 141,000 tons and the salinity concentration at Imperial Dam by about 14 mg/L.1/ Winter flows through the entire irrigation delivery system would be eliminated. The total cost-effectiveness would be about $762,000 for each mg/L of salinity reduction at Imperial Dam. The Lower Gunni son Basin feas ibil ity report/draft envi ronmental statement was completed in December 1982 and filed with EPA on January 4, 1983. Uinta Basin Unit, Utah Uinta Basin is located in northeast Utah, in Duchesne and Uintah Counties. The Uinta Basin contributes about 450,000 tons of salt annually through the Duchesne and Green Rivers. Return flows from 170,000 acres of irrigated 1 and account for approximately 240,000 tons of the salt contribution. The ASCS (Agricultural Stabilization and Conservation Service) and SCS (Soil Conservation Service) have continued to target areas in which onfarm improvements are to be made. The planning report of Reclamation is scheduled for completion in April 1984. The preferred plan for sys- tems improvement (i n the reduced area from that described in the Status Report), consisting of lining about 59 miles of canals and laterals, is estimated to reduce salt loading by about 24,000 tons annually, with a cost-effectiveness of about $900,900. l/ Based on CRSS formula. Feasibility report shows 141,000 tons reduction, 15.2 mg/L reduction, and cost-effectiveness of $702,000. xvi