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SUMMARY The Regional Director's proposed feasibility report for the Uinta Basin Unit of the Colorado River Water Quality Improvement Program is scheduled for completion in 1982. This status report will inform con- cerned interests of the preliminary, subappraisal level costs and impacts associated with the plan at this time. The Uinta Basin Unit investigation in northeastern Utah was author- ized by Public Laws 93-320 and 96-375 to determine the most cost-effectivel! way to reduce the salinity in the Colorado River system by reducing the quantity of poor quality water entering the Duchesne and Green Rivers. Irrigation return flows from these rivers flow eventually into the Colorado River carrying over 240,000 tons of salt from the study area. The salt is picked up from both off-farm and on-farm sources and results in an increase in salinity concentrations at Imperial Dam of about 24 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. Some of the irrigation facilities in the Uinta Basin were constructed as early as 1905 with little overall consideration for seepage prevention. 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 public involvement program aided in evaluating a number of alter- natives. In January 1981, the planning team recommended concrete lining as much of the canal and lateral system in the Uinta Basin as can be justified under the salinity reduction objective. In February, meetings were held in Duchesne and Roosevelt to present alternatives based on this recommenda- tion to the public for their information, and to solicit additional ideas or concerns. The table on the following page shows the two options presently being considered, one using saved water on presently irrigated lands, which is the preference of the local water users, and one not using saved water for irrigation purposes. The cost-effectiveness of each option is shown on both an incremental and a cumulative basis. The figures shown in the table are subappraisal level and may change with refinement of the plan. Additional computer model studies are being conducted which will illustrate the effects of the authorized Central Utah Project units on the salinity control program. Assuming Congress authorizes construction of the unit in 1985, construction could begin in 1989. Monitoring of system salt loads would continue throughout advance planning and during and after construction to determine effectiveness of the plan. 1/ Cost-effectiveness as it is used in this report is the cost per ~ mg/L 1n salt concentration at Imperial Dam. The Bureau of Reclamation is attempting through its salinity studies to determine which of the units of the Colorado River Water Quality Improvement Program have the greatest potential for salt concentration reduction for the least amount of,mong d d /" ,"," . J;8 expen e . l...j ~ti