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reductions under baseline demands are already reflected in the historical streamflow records so only the net reductions are of concern in this a_ alysis "' The District's withdrawals are reported in Attachment C by the type of supply utilized and according to where water was diverted. Diversions to both demand and storage by tributary rights (non- consumptive use), Colorado River rights, and the Plateau Creek Pipeline on Plateau Creek all result in reductions in the flow of the Colorado River. The operation of the Jerry Creek Reservoirs results in spills, which add to the flow in the Colorado River. Replacement reservoir releases also add to the flow of the river by replacing portions of the District's diversions to the WTP. Diversions of tributary consumptive use (CU) transfer rights by the District do not result in additional flow reductions by the District (as discussed in Section 3.2.4); likewise, releases from the Jerry Creek Reservoirs do not reduce flows. Both CU transfer water and reservoir releases are listed in Attachment C to show where the District obtains its water supplies during each month of the simulation. The historical streamflows, Section 7 flow reductions, and the reductions due to future Ute Water diversions, converted to units of cfs, are summarized together in Table 3.10. In addition, the tables also shows the gage height at the Palisade gage corresponding to the adjusted historical baseline flow and the reduction in that gage height which would occur given the flow reductions due to the District's future operations. Monthly values for all 19 years of the analysis are provided in Attxhment D. It should be noted that the annual average net flow reduction reported in Table 3.10 and Attachment D, 18,603 ac-ft/yr, differs slightly from the net diversions from the Colorado River Basin reported in Table 3.2, 18,521 ac-ft/yr. In fact, these represent the same value, the difference being in how they were calculated. Reductions reported in Table 3.10 were determined by calculating the difference in monthly diversions through the Ute Water system under baseline and future conditions. This calculation did not take into consideration the diversions and replacement releases to agriculture, as was done in Table 3.2. The Ute Water model was developed to operate only those components of the raw water system supplying the District. Incorporation of an ~' agricultural component would have required extensive modifications to the model. The agricultural factors were therefore only addressed on an average annual basis as in Table 3.2 and not on a monthly basis. This resulted in slight over-estimates of the flow reductions reported in Table 3.10 as compared to the values reported in Table 3.2, though the difference between the two is well within the accuracy of the evaluation methodology. The results in Table 3.10 show that average flow reductions would have ranged from 0.4 percent to 3.1 percent of the historical Colorado River flows under the future demand. In terms of average annual streamflow, the District's average flow reduction would have been about 25.7 cfs, or about 1.0 percent of the average adjusted Colorado River flow of 2,702 cfs for the period 1975 through 1993. In terms of changes in water levels in the Colorado River, reductions would be extremely small, averaging'/4- inch or less in any given month. The largest water level reduction observed-was less than one inch (see Attachment D - O.bS" in September 1985). Minor increases in water levels (0.01 to 0.02 inches) were observed in the months of August, September, and October when the CDM Camp Dresser & McKee o:~soa~_uo~ooanrrerro-a.noc B-14