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<br />. <br /> <br />. <br /> <br />C. Impacts of the "Check" on Orchard Mesa <br /> <br />Lowering the radial gates on the "check" structure <br />causes the water level in the power/pumping plant tailrace <br />(See Figure 2) to rise, decreasing efficiency for the <br />hyudraulic pumps and the power plant. OMIO is unable to <br />supply their full irrigation demand (Loss in delivery rates is <br />estimated at about 22 cfs) when the "check" is fully utilized, <br />and also experiences a decline in power revenues of about <br />$3,700 annually. <br /> <br />OMIO also has been paying all operation and maintenance <br />costs for the "check" and bypass channel since their <br />construction. By operating the "check" to benefit junior <br />rights in the "Cameo Call" group, OMIO has provided a service <br />to water users throughout the Colorado River basin, while <br />experiencing water shortages, decreased revenues, and <br />increasing operating costs. <br /> <br />O. Chanqes Under Full River Administration <br /> <br />In the early 1980's, OMIO hired its own management and <br />legal advisors, separating from GVWUA. Through a series of <br />letters and meetings, OMIO announced that it no longer <br />intended to operate the "check" outside the original intent of <br />the agreement with the United states and GVWUA. The state <br />Engineer and Division Engineer have agreed with this approach, <br />saying that the "check" would not be required unless OMIO <br />began generating power with water destined for GVIC. <br /> <br />This change in administration will have an impact on <br />Green Mountain Reservoir and the protection it can provide to <br />West Slope water users. Under historic "check" operations, <br />re-use of the power/pumping plant tailrace water was required <br />prior to making releases from Green Mountain Reservoir. In <br />the 1977 drought year, using the historic pattern of "check" <br />operations, about 66,000 acre-feet was released from Green <br />Mountain for West Slope uses. This figure is often quoted as <br />the maximum protection needed by West Slope users. That same <br />66,000 acre-feet may not be adequate today without a guarantee <br />that the "check" will be operated in the historic pattern. <br /> <br />Under strict river administration, the GVIC junior <br />right for 120 cfs will call for water directly from Green <br />Mountain Reservoir while the tailrace is allowed to drain <br />freely into the Colorado River below the GVIC diversion. To <br />assess the potential impact of the "check" under current <br />administration objectives, it was necessary to develop a <br />computer model to simulate daily fluctuations in the water <br />supply at Cameo. <br /> <br />- 9 - <br />