9413

• UCREFRP Catalog Number: 9413
• Author: Osmundson, D. B.
• Title: Flow Regimes for Restoration and Maintenance of Sufficient Habitat to Recover Endangered Razorback Sucker and Colorado Pikeminnow in the Upper Colorado River.
• USFW Year: 2001.
• USFW - Doc Type: Grand Junction.
• Copyright Material: NO

Additional calculations were required to determine the effect of regulation on annual
peak flows at the Cameo gauge. Linear regression was used to calculate the relationship
between total yield during the April-July period and the magnitude of average discharge on
the peak runoff day (Fig. 6). This relationship was derived by using a block of years that
occurred prior to the development of most regulation in the upper Colorado River basin
(i.e., preceding construction of Green Mountain Reservoir; Liebermann et al. 1989) and for
which monthly yield and peak discharge records were available (1902-1942). The
unregulated annual peak discharges at Cameo and the unregulated annual total yield for the
April-July period at Cameo as calculated by NRCS for the 1958-1997 period were then
predicted using this relationship.
To facilitate comparisons between average monthly discharges of regulated and
unregulated flows at Cameo, the 1958-1997 block of years was first divided into four
precipitation categories based on the total annual (Jan-Dec) unregulated yield at Cameo.
60
t 50
6
U) 40
C
W
Ch
6 30
L
H
0 20
10
a
0
%0 .
•
' y = 1483.21 + 0.01067 x
r2=0.78 P<.0001
0 1 2 3 4 5
Apr-Jul Yield (millions of acre ft)
Figure 6. Relationship between total yield at Cameo during the April-July runoff period and
the average discharge of the peak day. Data are from the 1902-1942 period of record;
1934-1942 data are from USGS gage at Cameo; 1902-1933 data are from USGS gage at
Palisade with estimates of Government Highline Canal diversion depletions added back.
Monthly yields (acre feet) were calculated from average monthly discharge (mean cfs x days
in month x 1.9835).
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