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00:169 32 In Figure 4~3, Demand No.1 represents a generic future demand increment The solution of this example network occurs in tWO steps. In the first step, Demand NO.1 may be satisfied only by direct river flow and does not have access to water held in reservoir storage. This is accomplished by assigning a lower rank to the demand delivery arc (Link No.1l) than the rank of active storage in the reservoir. The reservoir release arc (Link No.12) is closed to any now in the first step. In the second step, Link No.12 is opened and reservoir water is available to satisfy any shortages to Demand No. I. This is accomplished by holding flows in Link No.11 constant, or "freezing" the results of the first step. Link No.12,which has a higher rank than the active storage in the reservoir, will pull water from storage through Link No.12 to satisfY Demand NO.1 as needed. The following is a description of the assumptions incorporated inLO the Yampa Hivcr Basin Model with regard to a specific operatfon of existing reservoirs. These assumptions were gleaned from several sources including the Stagecoach Environmental Impact Statement. the Stagecoach Project revenue bond prospectus and various other reports on Steamboat Lake and Elkhead Reservoir .and from discussions with representatives of the Upper Yampa Water Conservancy District, the City of Craig and the Division of Parks. Stagecoach Reservoir Stagecoach Reservoir is owned and operated by the Upper Yampa Water Conservancy District. There are currently eight contracts for delivery of water from Stagecoach Reservoir to users below the reservoir. In addition, there are a number of contracts for Water delivery to irrigators upstream of Stagecoach by exchange with Yamcolo Reservoir. Ownership in Stagecoach Reservoir by Colorado Ute Electric Association consists of twO parts. There currently exists an exchange agreement which permits Colorado Ute to store 4,000 af allocated to Yamcolo Reservoir in Stagecoach Reservoir. This exchange agreement allows Yameolo to dedicate all its available storage to upMream users. The second portion of the Colorado Ute ownership in Stagecoach is for storage of 9,000 af. This storage volume is subject to reduction by tr.e Upper Yampa Water Conservancy District according to terms and conditions of the contract agreement. This reduction may be up to 4,000 af. The reduction amount is represented in the model as a separate account (mixed use active storage) which may be accessed by agricultural and municipal demands as well as Colorado Ute. The total Colorado Ute ownership is modeled as the 4,000 af exchange water from Yameolo plus the 5,000 affrom the Stagecoach contract (9,000 afminus the 4,000 afreduction). A municipal and industrial use account is modeled at :;,655 af. This account includes the seven existing M&1 contracts and additional un allocated active storage. The minimum Stagecoach Reservoir pooi is modeled as 16,640 af and includes a sediment pool (dead storage) 013,275 af.' . Representation of active and inactive storage in the model is accomplished by specifying four separate storage targets. These targets are as follows: 1) Colorado Ute (power) 9,000 af, 2) Mixed Use Active Storage 4,000 af. 3) Municipal and Industrial j,6j5 af, and 4) Minimum Pool 16,640 af. These targets add to the total reservoir capacity of 33,275 af. The Stagecoach operating license issued by the Federal Energy Regulatory Commission requires a release from Stagecoach Reservoir to maintain a streamflow of 20 cfs from AuguH 1 through Novembe'r 30. Stagecoach is also required to release the minimum of 40 cfs or the natural inflow from December 1 through July 31. These minimum flows are represented in the model by forcing a bypass through the reservoir.