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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by the committee members. In addition, The Nature Conservancy has proposed to
donate a 300 cfs conditional water right to the CWCB to be used for instream
flow purposes in that stream reach. Since the magnitude of this water right
was not decided at the time of model development, discussions were held with
the Technical Steering Committee and the Advisory Committee, and it was
decided to adopt a year-round minimum flow of 300 cfs as the baseline instream
flow regime for inclusion in the model. Furthermore, it was decided that for
the purposes of this study only, this minimum flow would be supported by
releases from storage in Blue Mesa Reservoir. The releases from the Blue Mesa
Reservoir were modeled in a manner that the releases would meet both the
seni or Gunni son Tunnel decree requi rements and the 300 cfs i nstream flows
value as long as the Blue Mesa Reservoir level is above the minimum power pool
It was assumed that the releases would be made with a priority date equal to
the conditional water right that The Nature Conservancy is presently (1989)
negotiating to donate to the CWCB, which is 1965. This assumption results in
protecting the minimum streamflow release against potential diversions by
downstream conditional water rights including the Mitex 1982 conditional
hydropower decree. Thi s model i ng assumption was sel ected for the foll owi ng
reasons: 1) it reflects the manner in which the river would actually be
administered downstream of the Aspinall Unit in the absence of an agreement
between competing water interests or a ruling permitting the Federal
government to retain dominion over releases made for instream flow purposes;
and 2) it quantifies the maximum effect such releases would have on Blue Mesa
storage. It should be noted that this was a model ing assumption only and as
such has no legal implications. Resolution of this issue must be obtained
outs i de of the study through appropri ate negoti at ions and 1 ega 1 proceedi ngs.
The assumptions made in this study can not be construed as being legally
binding on any affected parties including the USBR, the UVWUA, the CWCB, or
The Nature Conservancy.

The U.S. Fish and Wildlife Service (USFWS) is in the process, with the
cooperation of a number of other entities, of addressing the flow requirements
for endangered fish species in the Westwater Canyon area of the Colorado River
downstream of its confluence with the Gunnison River. These flows are

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