FLOOD01459

• County: Gunnison
• Community: Uncompahgre Valley
• Title: Upper Gunnison-Uncompahgre Basin Phase 1 Feasibility Study Summary Report
• Date: 5/1/1989
• Prepared For: Colorado Water Resources and Power Development Authority
• Prepared By: HDR Engineering, Inc.
• Floodplain - Doc Type: Project

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components were not included since they do not consume water, and because
modifi cat ions to reservoir rel ease patterns to accommodate recreation needs
will ultimately be established such that downstream water users will not be
adversely impacted. Therefore, only alternatives which include storage
reservoirs were modeled. In evaluating potential in-basin reservoirs, only
one alternative was modeled explicitly; namely, the development of three
reservoirs, one each on Ohio, Tomichi, and Cochetopa Creeks. Alternatives
representing development of a single reservoir or combinations of two of the
three reservoirs were not modeled.

Because of the Curecanti Subordination, which insures that in-basin
depletions under junior water rights are not called out by Blue Mesa
Reservoir, the hydrologic effects of individual reservoirs are largely
confined to the streams on which those reservoirs are located. Increased
in-basin storage and water use on anyone tributary above Blue Mesa generally
does not affect yields to in-basin water rights on other tributaries.
Therefore, the modeling of individual in-basin storage projects would not add
significantly to the information that could be obtained from modeling all
three reservoirs together.

The principal effect of developing all three in-basin storage projects
for irrigation use and streamflow enhancement is to correspondingly increase
late season inflow to Blue Mesa. This, in turn, increases the late season
physical supply available to the senior Gunnison Tunnel direct flow decree and
decreases late season dependence by the Tunnel on Taylor Park Exchange water
stored in Blue Mesa.

Five alternative in-basin reservoirs in three sub-basins were evaluated
using the basin model. These reservoirs include Castleton in the Ohio Creek
sub-basin, Elko and Sargents No.3 on Tomichi Creek, and Los Pinos and Pauline
in the upper Cochetopa drainage.

Scenario (model run) 2A evaluated a combination of Castleton, Elko, and
Los Pi nos reservoi rs. Results of thi s scenario showed that certai n