WSP10864

• File Number: 8220.102.01.I
• Description: Aspinall ‎(AKA Curecanti)‎
• State: CO
• Basin: Gunnison
• Water Division: 4
• Date: 1/1/1991
• Title: Scopes of Work - Endangered Fish Program as Related to Aspinall
• Water Supply Pro - Doc Type: Report/Study

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outline would be based on the results of analyses of how Aspinall
operation has affected the flow, temperature, and sediment regimes of
Colorado and Gunnison rivers and how these effects, in turn, have affected
the habitats of the endangered fishes, The work plan outline would be
available for use by researchers who desire to submit formal scopes of
work for consideration in the FY 92 budget cycle.

III. Study Goals, Objectives, End Product

A. Goal:

I. To identify the important changes to the hydrologic, temperature
and sediment regimes of the Gunnison and Colorado rivers that have
had probable negative effects on the endangered fishes.

2. To use the results of Goal 1 to develop a work plan outline which
identified studies important to the Aspinall Unit consultation.

IV, Study Area (river miles, if appropriate)
Colorado River, RM 0-170; Gunnison River, RM 0 to Crystal Da~

V, Study Methods/Approach

Knowledge of how Aspinall Unit operation has affected the hydrologic,
temperature and sediment regimes at key locations aiong the Gunnison and
Colorado rivers is essential to the identification and development of
future investigations, Analyses of predam and present.day hydrologic and
temperature regimes are being performed using empirical data and data
generated by the USFWS HYDROSS and TEMPERATURE models. Probable changes
in sediment dynamics are being assessed using available information. Key
river locations are the Gunnison River at river mile (RM) 20 and 2 (below
Redlands Diversion), and the Colorado River at Black Rocks (RM 132) and
Potash, Utah (RM 55), These sites were selected because they represent
river reaches downstream from the Aspinall Unit where Colorado squa~fish
may formerly have been abundant and spawned (Gunnison RM 20), areas whHe
the need to provide for fish passage is an important management concern
(Gunnison RM 2), river reaches that include important humpback chub
populations (Colorado River 132), and areas that provide habitat for all
life stages of Colorado squawfish (Colorado RM 132 and 55),

Analyses being performed at each site include determination of how the
Aspinall Unit has affected the magnitude of seasonal peak flows, the
frequency and magnitude of seasonal low flows, temperature regimes, and
sediment dynamics. Temperature-regime analyses would include assessments
of how Aspinall Unit operation has affected the occurrence of temperatures
believed important to both spawning and growth of endangered fishes,

After the analyses described above have been performed and the important
hydrologic, temperature and sediment regime changes attributable to
Aspinall operation have been identified, a review of the literature will

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