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~ . - ",.. -, ~ 0 3 U -,j;J.j;J' Description of Existing Model 3 Aspinall operations are represented only by Blue Mesa storage and release policies; Morrow POint and Cryslal reservoirs are assumed to operate as run-of.river facilities from a monthly perspective. Blue Mesa is operated on a forecast basis in J.rluary through July and on a declining storage target basis in AUllust through December. Blue Mesa storage rights, incorporating refill and net of inactive storage are set a.t 952,202 af; no direct flow power tights are represented. A schedule of minimum power releases, dependent on reservolr storage, is imposed. Additional storage releases are made lO suppon a 300 cfs minimum instrcam flow in the Black Canyon. Modeling of Uncompahgre Project operations includes Taylor Park. storage and release, diver. sion at tile Gunnison Tunnel, administration of the Taylor Park Exchange, and diversions and return flows in the main Uncompahgre Yd.Uey canals. Taylor Park is operated on a forecast basis for March through May and on an insueam Dow maintenance basiS in the other months. Gunnison Tunnel diver- sions are as cOnlCmplaled wlth AB Latera.l hydropower development in place; total tunnel diversions un. der the baseline scenario arc shown in Table B. 'llIe 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 nows. 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 W.d.ter bern-een Taylor Park and Blue Mesa for the purpose of I1shery enhancement on the Taylor and Gunrtison Rivers. The Exchange account parameters are monilored in the model and used ex oost 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 Bostwick Park 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. Oct.ober I when operations arc based on declining storage targets. Diversions of direct Dow and storage water are routed through the Cimarron Canal (up to a capacity of 145 cfs) to satisfy municipal and agri4.:uhural 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 (wintcr) and 25 cfs (summer) are imposed below the Canal headgate. Ridgway reservoir is operated on a forecast basis in January through July and on a declining slorage tar gel basis in the remai.ning months. Releases are made to irrigation use on an as.needed basis and to M&l use following a demand pattern derived from the Dallas Creek Definite Plan Report. The Ridb'WaY M&l demand of 28, 100 af is assumed to be exerted just below the reservoir oUllet because the precise location of the demand is yet unknown. lhe 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&I account in Ridgw.d.Y. Operations of both the Cerra and Fairview reservoirs are represented in the model. MODEL CAUBRATI0N The model was calibrated allainS! historical data for the years 1979 through 198~. Comparisons were made between historical gaged streamnows and reservoir contents and those predicted by the model. Model parameters rdating to simulation of operating procedures and to calculation of relurn flows were adjusted to a.chieve closer agreement between modeled and historical results. Graphical comparisons and correlauons between hist.orical and modeled results were used to judge calibration.