8221

• UCREFRP Catalog Number: 8221
• Author: Van Steeter, M. M.
• Title: Historic and Current Processes Affecting Channel Change and Endangered fish Habitats of the Colorado River Near Grand Junction, Colorado.
• USFW Year: 1996.
• USFW - Doc Type: Doctor of Philosophy.
• Copyright Material: NO

13

Chapter 2
THE STUDY AREA

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The study area is a 51 kilometer (32 mi) reach of the Colorado River
in the Grand Valley near Grand Junction, Colorado (Figure 2.1). A
substantial amount of research has been done on the biology of the
Colorado squawfish in the study area, but until the present study, there
had been very little research on the relationship between channel
morphology, discharge, and the habitats of the fish. The following chapter
reviews the physical characteristics of this reach, and the reasons why this
region is important for the recovery of the Colorado squawfish.
The Colorado River enters the Grand Valley near Palisade,
Colorado, flows approximately 22 kilometers (14 mi) to its confluence with
the Gunnison River, and then continues approximately 29 kilometers (18
mi) to Horsethief Canyon (Figure 2.1). The aerial photograph in Figure 2.2
illustrates the general character of the river through the Grand Valley.
The river is underlain by Mancos Shale of Cretaceous age with some
outcrops of Dakota Sandstone occurring in the downstream reach.
Although the river is constrained on its south bank in some areas by
sandstone or shale cliffs, this is an alluvial reach. The north bank of the
river has an extensive floodplain composed of gravel, sand, and silt. The
median surface sediment diameter throughout the reach is approximately
50 mm (Chapter 6). The slope of this reach is approximately 0.0015, and
the bankfull width ranges from 75 to 300 meters (245-985 ft).