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Reservoir Operating Studies 1 1 w Reservoir evaporation and storage carryover are automated in the model and storage and release operations are driven by the relative priorities between reservoirs and demands. The representation of releases from contract storage pools in the existing reservoirs was based on information provided by the operators of those reservoirs. Generally speaking, users holding existing contracts for storage water were the only demands allowed to have access to contract storage pools. Stagecoach Reservoir Stagecoach Reservoir is modeled as having three storage pools: an industrial pool of 9,000 af, a municipal pool of 7,635 af, and a recreation pool of 16,640 af. These pool allocations reflect implementation of the Yamcolo Exchange and anticipated reductions in the Tri-State contract. In addition to water supply releases from the first two of these pools, Stagecoach is also operated to generate hydropower and to maintain minimum instream flows below the dam. Demands assumed to have access to the industrial pool are the Craig Station (after it has exhausted its Elkhead supplies) and the Hayden Station (after it has exhausted its Steamboat Lake supplies), although the Hayden Station does not presently have a formal Stagecoach contract. Demands having access to the municipal pool are Steamboat Springs and Hayden, the Mt. Werner Water and Sanitation District, the Steamboat ski area (for snowmaking), and small industrial demands near Hayden. No water supply releases are made from the recreational pool. As a result of the Four Counties decree at Stagecoach Reservoir, in most years total ' decreed storage rights add up to greater than the physical capacity of the reservoir. Based on discussions with the Division 6 Engineer, it was assumed that this "excess" decree capacity would be administered as a refill right. This causes some complications in accounting between the two contract pools (municipal and industrial) and the recreation pool. Because of the additional decreed storage capacity over and above a single reservoir fill, there are instances when contract pools could partially refill and could potentially deliver more than their contract amount in a single year. While it is reasonable to expect this additional water to be stored rather than bypassed, the "refill" water in the contract pools would likely be held in storage for the next year. Therefore, the model limits deliveries out of the Stagecoach contract pools to their contract amounts (e.g., industrial = 9,000 of per year) even though additional water may L actually be available in the pools as a result of refill. Hydropower operations are implemented in the model by defining a set of decreasing ' end-of-month storage targets in the winter. Hydropower releases are made only when the reservoir is above this target after performing its other water supply release operations. The targets used call for a total drawdown of 10,000 of from full pool by the end of March each ' year. An "environmental release" is modeled below Stagecoach as required by the Stagecoach FERC license agreement. The minimum flow below the reservoir is either 20 or 40 cfs, depending on the season, or reservoir inflow; the 20 cfs is a hard minimum regardless of inflow. Releases from Stagecoach to satisfy this requirement are not counted against the annual ' storage decree limits if these releases are determined to be discretionary bypasses of free water, i.e., they are made in months when there was not a call against Stagecoach (this is usually the case inmost model scenarios). 2-7