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, "rlr~'m (r< 'D 5 S CH\- (; V1.e kc~~..f1&n 0) 0022J9 ~~~~n Mountain Reservoir (WnID 363543). This reservoir was constructed as an integral part of the CBT Project ',,\Vith the primary objective)f providing replacement water to Western Slope water users of the water that would otherwise be uSable"lr'said water was not withheld or diverted by the CBT Project (out-of-priority diversions/storage). A secondary purpose of the reservoir is store water for hydro-electric power generation and to supply existing irrigation and domestic water uses in the Colorado River basin. Green Mountain Reservoir is constructed on the mainstem of the Blue River and commands a drainage area of about 559 square miles, including the area above Denver's Dillon Reservoir. In addition to the mainstem of the Blue River, the reservoir is also filled using diversions from Elliott Creek via the Elliott Creek Feeder Canal (WDID 360606) with a capacity of 90 cfs. In the CRDSS WRPM, the Elliott Creek Feeder Canal is modeled as a carrier ditch which supplies water for the Green Mountain storage right. It is not operated as a direct flow right, independent of the storage fill limitations. Green Mountain Reservoir has a total capacity of about 153,639 acre-feet of which 6,860 acre-feet is dead storage and 146,779 acre-feet is live storage (33,985 acre-feet of inactive storage and 112,794 acre-feet of active storage). Pursuant to the provisions of Senate Document 80, 52,000 acre-feet in the reservoir (the Replacement Pool) is reserved for replacement of the out-of-priority depletions of the CBT Project (diversions through the Adams Tunnel and storage in Shadow Mountain, Granby and Willow Creek reservoirs). The remaining capacity of approximately 100,000 acre-feet (the 100,000 Acre-foot Power Pool) is used for the generation of hydro-electric power generation and the water that is released for power is available to supply existing irrigation and domestic uses on the Western Slope, at no charge. In 1984, the USBR promulgated a new operating policy for Green Mountain Reservoir that limited use of water from the 100,000 acre-foot power pool for existing Western Slope uses. The policy states that water stored in the reservoir for all existing uses, whose water rights were perfected by use prior to October 15, 1977, would be limited to 66,000 acre-feet. This modified storage pool is referred to as the historic user pool. Subsequent to the implementation of the new operating policy, the remainder of the 100,000 acre-foot pool (34,000 acre-feet) was set aside and made available for contract purchase by industrial water users (entities that were not entitled to the original benefits of Green Mountain Reservoir operations under the authorizing legislation of Senate Document 80) and by other users with water rights that were perfected by use after October 15, 1977 (The Contract Pool). This pool was later limited to 20,000 acre-feet. Since the initiation of the new operating policy, the division engineer has administered the releases from the historic user pool to benefit all uses that had perfected by use prior to January 24, 1984, the effective date of the new operating policy, as published in the Federal Register. However, for future operations, the beneficiaries of the historic user pool will be limited to those uses perfected prior to the specified October 15, 1977 date. These respective inclusion dates will be recognized in the historical versus baseline model scenarios in the CRDSS WRPM. Storage releases from Green Mountain Reservoir are released through the hydro power plant at rates of flow up to 1,726 cfs (WDID 360881). Although it carries its own direct flow water right, the power right has not been exercised historically to place an administrative call against upstream junior water rights. The USBR has historically operated the reservoir to maintain a minimum streamflow below the dam at 60 cfs. The Colorado Water Conservation Board has appropriated instream flow rights for the reach of the Blue River from Green Mountain Dam to its confluence with the Colorado River. These instream flow rights are 60 cfs for the period May 1 through July 15 and 85 cfs for the remainder of the year. It is the current policy of the USBR to honor these instream flow rights. There is also a general agreement that a bypass/release to maintain these minimum flows will not count against the allowable fill in Green Mountain Reservoir; therefore in the CRDSS WRPM, the bypass should be reflected as an operational right with a priority just senior to the 1935 storage rights for the reservoir. C.S.1.2 Historical Operation o/Green Mountain Reservoir From the time construction of Green Mountain Reservoir was completed (1948) until 1984, the reservoir was operated in strict accordance with the following provisions of Senate Document 80. 1. Whenever the flow in the Colorado River at the present site of said Shoshone Diversion Dam is less than 1,250 cfs, there shall, upon demand of the authorized irrigation division engineer or other State authority having charge of the distribution of waters of this stream, be released from said (Green Mountain) reservoir as part of said 52,000 acre-feet, the amount necessary with other waters available, to fill the vested appropriations of water up to the amount concurrently being diverted or withheld from such vested appropriations by the project for diversion to the Eastern Slope. 2. Said 100,000 acre-feet shall be released within the period from April 15 to October 15 of each year as required to supply a sufficient quantity to maintain the specified flow of 1,250 cfs of water at the present site of said Shoshone Diversion Dam, provided this amount is not supplied from the 52,000 acre-feet heretofore specified.