WSP01587

• File Number: 8220.101.17
• Description: Glen Canyon Dam/Lake Powell
• State: AZ
• Basin: Colorado Mainstem
• Date: 7/1/1998
• Author: Valdez/et al.
• Title: The Aquatic Ecosystem of the Colorado River in Grand Canyon - Grand Canyon Data Integration Project - Synthesis Report
• Water Supply Pro - Doc Type: Report/Study

Table a/Consents

LIST OF TABLES (Continued)

Table 8. Interactions Between Native and Non-native Fishes in the Colorado River through

Grand Canyon. ...................... ..... ..... ... .. ... .. .. ..... .. ..... 125
Table 9. Estimates of Humpback Chub Predation in Grand Canyon ..................... 130
Table 10. Driving Yariables and Postulated Effects of Experimental Steady Flows on Fish.... 142
Table 1 I. Matrix Showing Expected Responses of Native and Non-native Fish Species to
Hypothesized Effects of Experimental Steady Flows . . . . . . . . . . . . . . . . . . . . . . . . .. 173
Table 12. Information needs for lllluatic resources of the Colorado River in Grand Canyon, as
prioritized at the Project Workshop. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 184
Table 13. Research hypotheses for aquatic resources of the Colorado River in Grand Canyon, as
prioritized by Project Workshop biologists (N=6) ............................ 186

LIST OF FIGURES

Figure I. Map of the Color8do River Basin, showing the location of the project area from Glen
Canyon Dam to the mouth of Grand Canyon .. . . .. .. . .. . .. .. . . . .. . . .. . . . . . ... 3
Figure 2. Detail of the project lIrelI, which encompasses the Colorado River in Glen Canyon
(from Glen Canyon Dam to Lees Feny) and Grand Canyon (from Lees Feny to the

Grand Wash Cliffs) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 5
Figure 3. Species of native fish in Grand Canyon prior to 1850 . .. . .. . .. .. .. . .. . . . . . . .... 7
Figure 4. Annual volume of the Colorado River at Lees Fenyfrom 1922 to 1990 .......... 21
Figure 5. Mean daily flow of the Colorado River for two pre-dam water years, 1929 and
1940, as measured at the USGS gauge near mouth of Brigbt Angel Creek. . . . . . . .. 21
Figure 6. Pre-dam (WY 1947-1957) and post-dam (WY 1967-1971) average daily sediment
concentrations (mgIL) at the USGS gauge near Grand Canyon, Arizona (at Phantom

Ranch)................................................... .'.......... 23
Figure 7. Pre-dam and post-dam annual tmDperature trends based on monthly means at Lees
Feny and Near Grand Canyon (Mouth of Brigbt Angel Creek) ................. 25
Figure 8. Pre-dam and post-dam cross sections of the shoreline of the Colorado River in

Grand Canyon. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 27
Figure 9. Mean daily pre-dam (WY 1922-1962) and post-dam (WY 1965-1992) flow of the
Colorado River at Lees Feny . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 29
Figure 10. Seven operational scenarios for Glen Canyon Dam for WY 1963-1997, as recorded
at the USGS gauge at Lees Feny, Arizona ................................. 29
Figure 11. Mean monthly Colorado River tmDper&tl1re at Lees Ferry from 1955 to 1976 .. . . .. 33
Figure 12. Mean river temperature gradient downstream of Glen Canyon Dam during summer. 34
Figure 13. Pre-dam (above) and post-dam (below) lllluatic and temlstrial invertebrate
communities of the Colorado River corridor in Grand Canyon. ................. 37
Figure 14. Longitudinal sediment concentration and biomass of Cladophora and
macro invertebrates in the Colorado River from Glen Canyon Dam to Diamond

Creek. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 39
Figure 15. Algal-invertebrate assemblages typical of the Colorado River in Grand Canyon. . " 43

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