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Description of Existing Model 003111 , 3 . Aspinall operations are represented only by Blue Mesa storage and release policies; Morrow Point and Crystal reservoirs are assumed to operate as run-of-river facilities from a monthly perspective. Blue Mesa is operated on a forecast basis in January through July and on a declining storage target basis in August through December. Blue Mesa storage rights, incorporating refill and net of inactive storage are set at 952,202 af; no direci flow power rights are represented. : A schedule of minimum power releases, dependent on reservoir storage, is imposed. Additional storage'releases are made to support a ' 300 cfs minimum instream flow in the Black Canyon. Modeling of Uncompahgre Project operations includes Taylor Park storage andreJease, diver- sion at tile Gunnison Tunnel, administration of the Taylor Park Exchange, and diversions and return flows in the main Uncompahgre valley canals. Taylor Park is operated on a forecast basis for March through May and on an instream flow maintenance basis in the other months. Gunnison Tunnel diver. sions are as contemplated with AB Lateral hydropower development in place; total tunnel diversions un. der the baseline scenario are shown in Table 8. The diversions in the various Project canals are con. strained to be no more than canal capacities; diversions in excess of consumptive use under each canal are- routed as surface and subsurface return flows. The assumed capacities of the various Project facilities represented in the model are listed in Table 9. The 1976 Taylor Park Exchange agreement permits the exchange of storage wdtcrbetween Taylor Park and Blue Mesa for the purpose of fishery enhancement on the Taylor and Gunnison Rivers. The'Exchange account parameters are monitored in the model and used ex post to adjust allowable Tunnel diversions downward where necessary;' in the baseline scenario this adjustment was imposed in 1954 and 1977. " Silver Jack reservoir, on the Cimarron River, is the principal feature of the BostwkkPark Pro- ject. Silver Jack is operated with 12,820 af of active storage on a fill and spill basis except for the months of July through October, when operations are based on declining storage targets, Diversions of direct flow and storage water are routed through the Cimarron Canal (up to a capacity of 145 cfs) to satisfy municipal and agricultural demands in 'the 'Uncompahgre valley; the municipal demands are listed in Table 10 and are based on the aVerage yield of shares held by the Ciry of Montrose. Minimum flows of 15 cfs (winter) and 25 cfs (summer) are imposed below ihe Canal headgate.' Ridgway reservoir is operated on a forecast basis in January through July and on a declining storage target basis in the remaining months. Releases are made to irrigation use on an as-needed basis and to M&I use following a demand pattern derived from the Dallas Creek Definite Plan Report. The RidgwayM&1 demand of 28,100 af is assumed to be exerted just below the reservoir outlet because the precise location of the demand is yet unknown. The Project 7 Water Authority obtains water supplies from the Cimarron Canal and from the South Canal. Diversions from the Cimarron are limited to the average yield of shares owned by the City of Montrose. Diversions from the UVWUA's South Canal make up the remaining Project 7 demand, with a like amount of water released for irrigation use from the M&1 account in Ridgway. Operations of both the Cerra and Fairview reservoirs are represented in the model. MODEL CALIBRATION The model was calibrated against historical data for the years 1979 through 1983. Comparisons 'were made between historical gaged streamflows and reservoir contents and those predicted by the model. Model parameters relating to simulation. of operating procedures and to calculation of return flows were adjusted to achieve closer agreement between modeled and historical results. Graphical comparisons and correlations between historical and modeled results were used to judge calibration.