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I I I I I I I I I I I I I I I I I I I 000426 Executive Summary provide for this subordination. This strategy would tend to minimize the need for additional water storage in the basin but would also reduce the flows that could be legally called for by the instream water right. The second strategy (which defines, in a sense, an opposite extreme) would be to transfer a portion of the Juniper water rights to existing and future reservoirs in the basin with the remainder of the rights being transferred to instream flow; in this case, the reservoirs would serve to supply water directly to all the existing and future uses which would otherwise be called out by the more senior priority of the instream flow right. The reservoirs would essentially act as sources of augmentation for these junior rights. This strategy would to maximize the flows that could be legally called for by the instream flow rights but would also tend to maximize the need for additional storage in the basin. In all likelihood, the final resolution of the transfer will involve aspects of both of these strategies in some combination that respects the decreed benefits of the general subordination while providing inadequate seasonal instream flows regime. Although the final terms of the transfer are still unresolved, it was decided that, by examining the two strategies described above, the Study would "bracket" the range of possibilities of the final resolution. The subordination-only strategy was evaluated in model Scenario II while the augmentation strategy was evaluated in model Scenarios III through V. Model Scenario I evaluated the future implications of doing nothing with the Juniper Project water rights. Nothing in the choice and definition of these model scenarios should be construed. as a legal position or interpretation concerning the Juniper Project water rights or subordinations thereof. WATER USES AND NEEDS Projections of near-term (year 2015) and long-term (year 2040) water demands in the Yampa River Basin were an important component of this study. The projections were requiredto adequately plan water supply systems and estimate water deman&.> for the future economic development of the basin. Projections of water demands were also used in sizing and siting storage facilities and in operations studies for proposed reservoirs. Recent water use data (Davenport, 1990; USDI, USGS, 1989; CDWR, various years) were used to estimate 1989 actual and potential water use in the basin. The potential demand under 1989 conditions was an estimate that assumed greater utilization of existing facilities and allowed for higher but not unprecedented depletion rates. Potential municipal use included a 36 percent increase over 1989 use and was meant to allow for high demands that could be experienced during a dry summer. The potential thermoelectric use estimate allowed for 90 percent utilization of existing generation capacity and the highest water use per unit of generation at Craig and Hayden observed over 1985 to 1989. The potential irrigation use was based on 75,000 irrigated acres, slightly more than the highest historical value of 73,300 acres estimated for 1983, and 1.11 acre feet (at) of depletion per acre estimated for 1989. Potential evaporation and export figures were the highest calculated by the State Engineer's Division 6 office over the 1981 to 1989 period. Potential demand estimates for 1989 were used as the base condition since supply planning should be based on potential demand rather than observed use. Also, the use of potential demands provided a more conservative estimate of future water needs. . Rates of population growth in Moffat and Routt counties for the periods 1960 to 1990, 1970 to 1990, and 1980 to 1990 were estimated from historical census data. The 1970 to 1990 rates (2.8 and 4.3 percent in Moffat and Routt, respectively) were used to project increases in S-5 ,j,j