8274

• UCREFRP Catalog Number: 8274
• Author: Pitlick, J. and R. Cress.
• Title: Longitudinal Trends in Channel Characteristics of the Colorado River and Implications for Food-Web Dynamics.
• USFW Year: 2000.
• USFW - Doc Type: Recovery Implementation Program Project 48-C,
• Copyright Material: NO

Average annual hydrographs of the Colorado River constructed for separate periods before and
after 1950 illustrate the changes in streamflow patterns caused by reservoir operations and flow
diversions (Fig. 3). Compared to the period prior to 1950, peak discharges in spring and early
summer are now much lower than they were before, and base flows in fall and winter are higher.
Our analysis of streamflow records from the Cameo and Cisco gauging stations indicates that, since
1950, instantaneous peak discharges of the Colorado River have decreased by 29 and 33%,
respectively, at these two sites (Cress, 1997).
a)
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Figure 3. Average annual hydrographs of the Colorado River for separate periods; (a) Colorado
River near Cameo, CO and (b) Colorado River near Cisco, UT. Note the September and October
spikes in flow in the pre-1950 Cisco hydrograph; these correspond to individual monsoon storms.
The same spikes do not appear in the Cameo record because this gauge is located near the northern
edge of the monsoon's influence (Fleener, 1997), and they are not as evident in the recent portion
of the Cisco record because of the influence of McPhee Reservoir on the Dolores River.
Colorado River near Cameo, CO
Colorado River near Cisco, UT
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