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t Executive Summary needs. The decrees entered in cases 83CW143 and 91CW31 by the Division 6 Water Court 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 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 an adequate seasonal instream flow 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 I while the augmentation strategy was evaluated in model Scenarios III through V. (Model Scenario I also showed that the "subordination only" strategy is functionally equivalent to doing nothing with the Juniper 1 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 subordination 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 required to adequately plan water supply systems and estimate water demands for 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 otential water use in the basin . p The estimated potential demand under 1989 condition 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 of 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. 1 S-7