CRDSS_Task1_15-25_UncompahgreProject

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If the Gunnison Tunnel is flowing full with direct flow water, the flow at the Olathe gage is ? substantially greater than zero, and the irrigation demands are fully satisfied, then the UVWUA will cut back on its diversions through the tunnel, as necessary. If the Tunnel is flowing full with direct flow water, the flow at the Olathe gage is near zero, and ? the irrigation demands are not satisfied, then the UVWUA may elect to either (a) place a call against junior water rights on the Uncompahgre or (b) request a release of its 10,300 acre-feet of Dallas Creek Project water (or its Project 7 Exchange Water) from storage in Ridgway Reservoir. Similarly, if the system demand is not satisfied and the yield of the tunnel's direct flow right is ? less than the tunnel capacity of 1,135 cfs, the UVWUA then must decide whether to begin releasing water from Taylor Park or to place a call against junior water rights on the Uncompahgre and/or Gunnison rivers. This is a subjective decision that is made by the UVWUA after considering the amount of water in storage, climatic conditions, and how much of the irrigation season remains. If this situation occurs early in the season and the UVWUA elects to preserve its storage water for use later in the summer, then the UVWUA is likely to place a call against junior rights on the Uncompahgre main stem. If it is later in the season, the decision will likely be made to release water from storage rather than to place a call on junior rights. It is assumed that the UVWUA will not normally place a call when the tunnel is not flowing full. The physical capacity of the M & D Canal, the largest and most upstream project canal, is between 550 and 600 cfs; the canal is operated at full capacity for the majority of the irrigation season. If the UVWUA elects to place a call against Uncompahgre junior rights (prior to releasing storage water), the UVWUA and the Division Engineer have an informal agreement about the administration of such a call. Interview information indicates that the UVWUA will only call up to approximately 245 cfs, which will be delivered to the head gate of the M & D Canal. This value is determined as the cumulative sum of the all the senior priorities decreed for diversion at the M & D head gate up through Administration number 12516 (see Table 1). It must be noted that all other project demands (including the remaining demand at the M & D head gate) are supplied from the UVWUA's other sources (the Tunnel direct flow diversions, storage releases from Taylor Park [Blue Mesa] and Ridgway, and return flows from upgradient irrigation). Junior water rights that would be impacted by a call on the Uncompahgre River would be those rights with Administration numbers greater than 12516, both upstream and within the project reach of the Uncompahgre River. The U.S. Geological Survey (USGS) stream gage for the Uncompahgre River at Colona is used to administer the Uncompahgre Project water rights. This gage is upstream of the M & D head gate and the point where the South Canal delivers Gunnison Tunnel water to the river. According to the Division Engineer, the Water Commissioner, and the UVWUA Manager, if the flow at Colona is 800 cfs or greater, there is generally adequate water for all of the downstream diversion demands of the project canals and other non-project water rights. When the flow is less than 800 cfs, it is necessary for the UVWUA to supplement its supply using the Gunnison Tunnel and eventually storage water. Later in the irrigation season (typically around mid-July), the tunnel is typically flowing full (either with direct flow diversions or Taylor Park storage water). Then, if the flow at Colona is still greater than 250 cfs, the UVWUA would not likely place a call against junior water rights on the Uncompahgre, and would draw upon its storage in Ridgway Reservoir. If the flow is less than 250 cfs, the UVWUA would likely place a 5 A275 01.09.95 1.15-25 Fosha, Hyre