CRDSS_Task1_15-20_DallasCkProject_RidgwayRes_Project7WaterAuthority

• Title: CRDSS Task 1.15-20 - Water Rights Planning Model - Dallas Creek Project ‎(Ridgway Reservoir)‎ - Project 7 Water Authority
• Description: This memorandum describes the operation of the Dallas Creek Project and its principal component, Ridgway Reservoir, constructed on the main stem of the Uncompahgre River near the Town of Ridgway.
• Decision Support - Doc Type: Task Memorandum
• Date: 1/9/1995
• DSS Category: Surface Water
• DSS: Colorado River
• Basin: Colorado Mainstem
• Contract/PO #: C153658, C153727, C153752
• Grant Type: Non-Reimbursable
• Bill Number: SB92-87, HB93-1273, SB94-029, HB95-1155, SB96-153, HB97-008
• Prepared By: Riverside Technology inc.

governed by the flow conditions in the Uncompahgre River and the available diversions
through the Gunnison Tunnel (see Task Memorandum 1.15-25).

Ridgway Reservoir is filled when its storage right is in priority. In order to reflect the
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TCWCD's "fill without spill" policy, reservoir target storage levels adopted for the Gunnison
River Basin Planning Model (GUNMOD) were also used for the CRDSS model. These levels,
from October through March, are as follows:
October74,000 acre-feet
November71,000 acre-feet
December68,000 acre-feet
January68,000 acre-feet
February 68,000 acre-feet
March68,000 acre-feet
During the spring and summer months, the target levels vary and are dependent upon the
predicted runoff values adopted in the GUNMOD studies.
3.0 CONCLUSIONS AND RECOMMENDATIONS
The MODSIM prototype for the Gunnison River basin was developed to simulate the operations of
Ridgway Reservoir and the various sub-accounts for allocating and using the stored water therein.
MODSIM also has been designed to simulate the Ridgeway exchange that enables high-quality water
imported by the UVWUA from the Gunnison River basin to be used by the Project 7 water authority in
exchange for a transfer of water from the municipal and industrial account in the reservoir to the
irrigation account of the UVWUA. The model is structured to maintain accounting of the individual
accounts in Ridgeway in accordance with the agreements.
Storage targets for the operation of Ridgeway Reservoir were obtained from the GUNMOD model for
October through March. For the remaining months, the GUNMOD targets were not used because they
tended to drain too much water from the reservoir. The CRDSS consultants derived a set of modified
targets that will more closely reflect historical operations and will keep the reservoir full without spilling.
The on-line documentation for the MODSIM prototype contains additional information about how these
operations are implemented in the water rights planning model.
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A275 01.09.95 1.15-20 Fosha, Hyre