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JOLJ7.:.5 The Service requested that the baseline hydrology should be the C1 Data Set hydrology with the existing flow-related RIPRAP projects included and the Category 2 (i.e., future) depletions excluded (Maddux, February 2, 1999 and clarification from Bob Muth to Leo Eisel, May 5, 1999). Communication with CWCB concerning the baseline hydrology indicated that this data set (C1 Data Set hydrology with RIPRAP flow related projects and without the 60,000 acre-feet or 120,000 acre-feet of future projects) was available for the Phase 2 investigation. This data set also included provision for the Green Mountain Reservoir Historic User's Pool (HUP) surplus. HUP surplus is that water estimated in late summer to not be needed for replacement purposes and which can be released for authorized purposes. The baseline hydrology initially used for analysis purposes in Phase 2 is the 1975 through 1991 monthly flow data used in the C1 Data Set. It was originally thought that the C1 Data Set as received from the State included the RIPRAP projects as listed in the PBO and did not include the 60,000 acre- feet or 120,000 acre-feet per year of estimated depletions from new projects. Subsequent to the initial use of the C1 Data Set in the Technical Memos, it was determined that not all the operation rules necessary for including the RIPRAP projects were implemented (i.e. "turned on") in the version of StateMod and the C1 Data Set received from the State. As discussed in Sections 2.3.2.2 and 2.3.3, the nec~ssary operational rules were turned on in C1 Data Set Fourth Revision to include the RIPRAP proJects. I 2.3.2.2 Modifications. Modifications to the original C1 Data Set as supplied by the State were necessary in order to carry out the Phase 2 analysis of the alternatives. These modifications included: . The original Cl Data Set scenario as supplied by the State was modified by adding full reservoir targets in Green Mountain Reservoir for the months of September and Octo ber. This prevented discretionary hydropower releases until after the irrigation season but did allow releases to HUP beneficiaries, including the USA power plant. "In addition, monthly demands of 20,000 acre-feet were added to diversion ill #952001 corresponding to the projected 20,000 acre-feet releasesto enhance the spring runoff in the 15-Mile Reach in 1975, 1978, 1979, 1980, 1982, 1985, 1986 and 1991. Finally, any water rights were eliminated from that diversion to prevent the right from simply taking credit for water in the stream when available. . Based on conversations with the Bureau of Reclamation, all Green Mountain Reservoir water in storage on April1Sl of each year is credited to the CBT account and any remaining water is designated as HUP water. An operational rule was added to the C1 data set to reflect this action in the C1 Data Set First Revision. The original C1 Data Set data set included a free river refill right to allow any reservoir with available storage to store water under free river conditions, as is normal practice. However, Ruedi Reservoir has an adjudicated refill right and thus this right was incorrectly given a priority number of 99999.99 in the C1 Data Set. The correct priority number of 47869 was used in the C1 Data Set Second Revision. . As the Phase 2 investigation progressed it was necessary to make further modifications to the C 1 Data Set. The modifications are summarized in Table 2 and are further described in Appendix M. These modifications primarily involve: . . Including the reduced demands for diversion resulting from the Grand Valley Project.. P:\Data \GEN\CWCB\19665\Repon Phase 2\FinalRepon12,Q2\Final_ Draft _ Repon(l-03).doc 18.