7273

• UCREFRP Catalog Number: 7273
• Author: Prewitt, C. G., E. J. Wick and D. E. Snyder.
• Title: Population and Habitat Monitoring Program for the Endangered Humpback Chub ‎(
• USFW Year: 1978.
• Copyright Material: NO

5.
Colorado River - Middle of the Black Rocks area in Ruby Canyon
(immediately below fish collection site F). This reach is
unique and does not represent other portions of the canyon above
or below Black Rocks. Numerous squawfish and humpback chubs
have been captured in this exceptionally deep area (Sealing,
et al. 1975).
METHODS
Aquatic habitat within the trend zones was assessed in two distinct
ways. First, a float trip was conducted through each trend zone and general
geomorphologic,land use and riverine features noted. This procedure allowed
detailed visual assessment of areas and activities which might change in scale
or nature such as irrigation, gravel mining, mechanical stream channel changes,
road maintenance, grazing, bankside stabilization or urban development. Also,
the general vegetative covEr on alluvial islands and both streaw banks was
characterized by density and type. Stream depths were measured continuously
during float trips, and notations made of areas providing especially deep or
critically shallow waters. Very shallow areas were marked for possible future
assessment by single-cross section instream flow methodologies such as that
used by the Colorado Division of Wildlife.
All observations made during float trips were recorded on Xerox copies
of topographic maps (Fig. 2-6) and each trend zone was further documented
with color slides (Appendix C).
The second habitat assessment technique involved the measurement of
certain representative river reaches within all but one trend zone by standard
river-channel surveying methods. At each "habitat measurement area" five
channel cross-sections and their water surface elevations were surveyed.
. Each cross-section contained a minimum of nine segments in which substrate