WSP05499

• File Number: 8200.766
• Description: Gunnison River General
• State: CO
• Basin: Gunnison
• Water Division: 4
• Date: 4/1/1997
• Author: Mueller and Hiebert
• Title: Assessment of Kokanee Salmon Transport through Blue Mesa Powerplant - Colorado - During the Spring and Summer of 1994-1996
• Water Supply Pro - Doc Type: Report/Study

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Blue Mesa Dam Fish Passage

The majority (96\) of fish being lost from the reservoir were young
(~120 mm) kokanee salmon. Transport rates varied from .0001 to .1400
fish/acre/ft(1.135e-04 fish/m') and also showed pronounced fluctuations
in fish passage between day and night. The passage of kokanee during
the spring/summer of 1994, 1995, and 1996 was estimated at 770,
60, 837, and 11,007 respectively.

The sieve netting program provided us valuable information concerning
fish passage during the peak flow period in 1994 through 1996. Year
round sampling would have been preferable, however, winter sampling
would have been unsafe and impractical because of icing.

These transport rates are similar to the estimates made by Van Buren
(et al. 1981). He estimated kokanee passage of 45,500 per year
through stocking records, mortality assumptions and estimated
proportion of standing crop in the downstream Morrow Point Reservoir
in 1977. These estimates were used to give magnitude of loss rather
than specific estimates and the 1977 loss was 5 to 7 percent of the
initial stocked numbers.

Fish passage rates were intended to help determine specific fish
losses due to FWS flow criteria. Unfortunately, several factors
complicated the analysis. The most confounding problem was the
abundance of water during the study. It's impossible to identify any
flows during 1994-1996 that can be specifically attributed to FWS flow
recommendations. Secondly, we have an extremely limited baseline
which does not include any low water years and we do not have any
information regarding transport rates or fish distribution in the
intake channel during the winter.

The shifting of winter releases to meet spring release criteria was
not necessary because of.the above average runoff. The most
concentrated sieve netting effort was during 1995 when run off was +75
percent of normal. Figure 17 shows that flows at Grand Junction,
Colorado met or exceeded recommended minimal flow recommendations for
all years and in 2 of the 4 years actually surpassed maximum flow
criteria for May through August. Unfortunately, during this period of
time, it'S impossible to identify any releases that were made
specifically to meet FWS test flow criteria. There was simply an over
abundance of water in the system.

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