WSP04343

• File Number: 7630.325
• Description: Wild and Scenic-Gunnison River-Curecanti Unit
• State: CO
• Basin: Gunnison
• Water Division: 4
• Date: 12/1/1986
• Author: WBLA inc
• Title: Gunnison-Curecanti-Curecanti Instream Flow Water Rights Study
• Water Supply Pro - Doc Type: Report/Study

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The model does not, however, reduce storage releases by the amount of

monthly evaporation; as a result, reservoir contents are most often left

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slightly below target due to evaporation. Annual evaporation at Blue Mesa

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only averages about 8,000 acre feet, and does not significantly influence

the study results. This average amount of evaporation seems low, but is

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consistent with the annual evaporation reported by the USBR for Blue Mesa

and appears to represent net evaporation after accounting for

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precipitation. Derivation of evaporation rate and reservoir volume/area

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relationships are described in Section 3 of the Technical Report.

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I. Fish Flows

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Historically, Blue Mesa storage releases have beerr made to maintain a

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200 cfs instream flow for the Gold Medal trout fishery in the 29-mile

reach. It has been proposed that the releases be increased so as to

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maintain a 300 cfs instream flow for these purposes.

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It has also been proposed that Blue Mesa storage releases be made to

maintain a 2000 cfs instream flow for endangered fish in 9 years out of 10

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at Westwater near the state line on the Colorado River below the mouth of

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the Gunnison. Preliminary data indicate that under projected levels of

development, a 500 cfs Blue Mesa release over historic levels (200 cfs)

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must be made during August and September in order to maintain the 2000 cfs

flow at Westwater.

If Blue Mesa releases are to be increased over

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WBLA, Inc. 1909 Broadway, 13, Boulder, Colorado 80302

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