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represented by a complex series of arcs connecting the storage to the river flows and to the <br />direct flow nodes which have access to storage. <br />Currently the Yampa Model includes detailed monthly operation of ten reservoirs. Numerous <br />sub-accounts in each reservoir (where applicable) have been defined to specifically connect a <br />reservoir sub-account to a ditch structure entitled to use reservoir water. Because of the <br />number of reservoirs and explicitly modeled sub-accounts, it is believed that there is more <br />specific definition of the Yampa River basin reservoirs in the Yampa Model. <br />It is clear that the objectives of the YRBAS modeling efforts and those of the CDSS are <br />sufficiently different to explain the principal differences in the two modeling approaches, <br />particularly as it relates to the number of water right structures that are being explicitly <br />modeled in the CDSS and the more intensive focus on future development scenarios and <br />reservoir storage options being addressed in the YRBAS. Accordingly, assumptions and data <br />requirements for the two models vary substantially. There are a number of assumptions, <br />described in the documentation for the YRBAS, that differ from those included in the CDSS. <br />These are briefly discussed below: <br />^ The YRBAS does not specifically model irrigation rights above Stagecoach <br />Reservoir. From interviews with the division engineer, it appears that this is one of <br />the few areas in the Yampa River basin that requires administration and may, from <br />time to time be water short. Accordingly, it is important for the CDSS to model the <br />upper reaches of the Yampa River in detail rather than an aggregated demand. <br />The cumulative water rights at the Craig Station power plant are in excess of the <br />90.63 cfs described in the YRBAS documentation, if the water rights for the <br />Synthetic Products Ditch are included. The latter is significant since it is senior to the <br />Juniper water rights. There are also certain diversion limitations on some of the direct <br />flow rights, based on conditions imposed as part of the transfer proceedings. We <br />agree with the YRBAS in regard to the actual diversion demands at Craig Station. <br />^ The YRBAS documentation implies that the industrial water in Steamboat Lake <br />(5,000 acre-feet) can only be used at the Hayden Station after the industrial storage in <br />Stagecoach Reservoir is depleted. We are not aware of any such limitations. Hayden <br />Station does not have access to storage in Stagecoach Reservoir. <br />We believe the sub-accounts in Stagecoach Reservoir are misrepresented in the <br />YRBAS. The industrial account in Stagecoach Reservoir now owned by Tri-State <br />Generation and Transmission Association (Tri-State) contains a total of 11,000 acre- <br />feet (7,000 acre-feet attributable to the Stagecoach water rights and 4,000 attributable <br />to the exchange with Yamcolo Reservoir). Storage in Stagecoach Reservoir is now <br />allocated as 11,000 acre-feet to Tri-State; 2,000 acre-feet to existing municipal <br />contracts, 2,000 to unallocated M & I contracts and 18,275 acre-feet to recreation and <br />dead storage. <br />Yampa River Basin Information 5-4 <br />