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FINDINGS AND RECOMMENDATIONS ~ (,') c:n ..... The findings and recommendations briefly summarized here are the result of a joint evaluation conducted by the Department of the Interior and the Department of Agriculture. The fin- dings are presented as a program management tool to accom- plish salinity control objectives at minimum cost. This approach to long-term, programwide interagency analysis is helpful to Federal program managers when weighing budget and program decisions each year. The 1986 evaluation was prepared using data adjusted to more accurately compare the program information of the two departments. All costs (January 1986) and interest or discount rates (8 5/8 percent) have been adjusted to the same base. Repayment from the Lower Colorado River Basin Development Fund was based on the current 10 5/8 percent interest rate. The base condition for the CRSS (Colorado River Simulation System) computer model evaluation assumes no funds expended on salinity control beyond those already spent on Grand Valley, Meeker Dome, Uinta Basin, and Las Vegas Wash. These projects, or portions thereof, are currently removing approximately 126,800 tons of salt annually from the river system. Projections of future salinity conditions used the average of 15 sequences of historical hydrology (1906-1983) as a data base and current (1986) Bureau of Reclamation depletion projections (similar to the Forum's moderate depletion level). The salinity at Imperial Dam is projected to reach about 963 mg/L by the year 2010. Using the salinity projections at Imperial Dam, salt load reductions required to reduce projected TDS (total dissolved solids) levels to the numeric criteria level of 879 mg/L were estimated to be 1,090,000 tons per year by the year 2010 and are referred to as the program objective. Because of hydrologic fluctuations in the Colorado River Basin, the salt load reduction objective would be met at least 50 percent of the time in the future. In confirming the effectiveness of the recommenred plan to fully satisfy salt load reduction objectives and program goals, salinity projections at Imperial Dam, with and without additional program controls, are shown in figure 1. Figure 1 provides an historical perspective in addition to the numeric standard and the projections at Imperial Dam. It is readily apparent that with or without the recommended controls, the salinity at Imperial Dam is expected to increase significantly over the next eight years.