7621

• UCREFRP Catalog Number: 7621
• Author: Woodling, J.
• Title: Colorado's Little Fish
• USFW Year: 1985.
• USFW - Doc Type: A Guide to the Minnows and Other Lesser Known Fishes in the State of Colorado.
• Copyright Material: NO

Habitat Types Found in Colorado Rivers
Though fish communities differ in the
various river basins of Colorado, some of
the habitat types are quite similar. Prob-
ably the most well known river habitat in
the state is that of the coldwater moun-
tain trout stream. The headwaters of four
major drainages in the state, the Platte,
Arkansas, Colorado and Rio Grande, are
of this stream type. Cold, clear water flows
rapidly downstream through an alternat-
ing series of rapids and pools. The river
substrate is commonly composed of
gravel-to-boulder size rubble. Dissolved
oxygen levels are usually very high, with
low dissolved solids and cold water
temperatures. Streams are frequently
shaded by trees and bordered by grasses.
On the western slope of Colorado, trout
streams and smaller rivers merge to form
the "Big River" habitat. These rivers
including the Colorado, Yampa, White,
Dolores, and Animas, small in compari-
son to other states, with low fall flows,
(sometimes far less than 1,300 cubic feet
per second) are indeed large for Colorado.
Stream velocity still remains high, espe-
cially during the spring runoff as snow
melts in the high country. During periods
of low flow, stream velocity in eddies,
pools and main channels can be quite
slow and languid. Pools can be twenty or
more feet deep while the rapids form
whitewater areas favored by rafters. The
stream substrate is composed of boulders
and large rocks in the rapids. Gravel and
sand bars are found in areas of slower
The Arkansas River above
John Martin Reservoir on the
Eastern Plains.
water. In pools and eddies the riverbed is
usually covered by mud and silt. Oxygen
content of the water is usually high, while
dissolved salt concentrations are mod-
erate and summmer water temperatures
are rather warm. In most locations there
are no trees bordering the rivers. Stream
banks are composed of sedimentary rock
deposits or rubble, with some gravel and
sand beaches.
As the "Big Rivers" flow through the
western portions of Colorado, smaller
tributaries join the mainstems. Following
spring runoff, stream volumes of these
small tributaries are often quite low. The
substrate of these streams is usually com-
posed of moderate-sized cobble, sedimen-
tary rock gravel or silt and mud. During
West Plum Creek is a typical `';
transition zone stream.
Colorado's Little Fish