9545

• UCREFRP Catalog Number: 9545
• Author: Chart, T. E. and L. Lentsch.
• Title: Flow Effects on Humpback Chub ‎(Gila cypha)‎ in Westwater Canyon - Final Report.
• USFW Year: 1999.
• USFW - Doc Type: Aspinall-46,
• Copyright Material: NO

LIST OF FIGURES
Figure 1. Map of the Westwater Canyon study area: BLM put-in Colorado River RK 204.3 (RM
127.2) to Cottonwood Wash at RK 179.5 (RM 112.2). Young of year sampling sub-reaches
(above canyon, canyon, and below canyon are delineated as are the three fish community
sampling sites (boxed areas). River miles refer to distance from the Green /Colorado
confluence at RM 0.0 as referenced in Belknap's Revised Canyonlands River Guide .... 34
Figure 2. Mean daily flow (cubic feet per second) as recorded by the United State Geological
Survey at the Colorado River Near Colorado-Utah State Line (State Line) gage.
Gage No. 09163500. January 1, 1992 -September 30, 1996 ....................... 35
Figure 3. Pre- (1923-1965) and post Aspinall (1966-1996) exceedence flow plots for the Colorado
River at the Near Cisco, Utah, station (gage No 09180500). Top graph -peak flow (cfs)
analysis; middle graph -total annual flow (acre-feet), and bottom graph -runoff flow
analysis (April -July flow volumes (acre-feet)). Values for the study years (1992-1996)
are depicted . ............................................................ 36
Figure 4. Correlation of YOY chub hatch dates for the above canyon and canyon sub-reaches
plotted against respective spring peak flow as recorded at the State Line gage. Least
squares regressions lines were hand drawn. The outlier was the 1993 data point ....... 37
Figure 5. Number of YOY chubs spawned (data graphically represented in bars; reads off of
secondary Y- axis) above Westwater Canyon as determined through back calculation.
Spawning data plotted against Colorado river flow (primary Y-axis) and main channel
temperature (secondary Y-axis) as recorded by the USGS at the Near Cisco, Utah, gage
(No. 09180500); 1992, 1993, 1994, and 1996 ................................... 38
Figure 6. Number of YOY chubs spawned (data graphically represented in bars; reads off of
secondary Y- axis) in Westwater Canyon as determined through back calculation.
Spawning data plotted against Colorado river flow (primary Y-axis) and main channel
temperature (secondary Y-axis) as recorded by the USGS at the Near Cisco, Utah, gage
(No.09180500);1992-1996 ................................................ 39
Figure 7. Correlation of daily growth (mm/day) for YOY chubs collected in July and August in the
above Westwater Canyon and Canyon sub-reaches to accumulated monthly degree days
(>20°C). Thermal data collected by the USGS at the Near Cisco gage (No. 09180500):
1992-1996 ............................................................... 40
Figure 8. Summary plot of YOY CPEs by trip for each sampled sub-reach. Westwater Canyon of
the Colorado River, Utah; 1992-1996 ......................................... 41
Figure 9. Scatter plot of July and August, 1992 - 1996, YOY chub CPEs against respective spring
peak as recorded at the State Line gage. Data presented for the above canyon and canyon
sub-reaches in Westwater Canyon, Colorado River .............................. 42
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