7078

• UCREFRP Catalog Number: 7078
• Author: Carlson, C. A. and R. T. Muth
• Title: Colorado River
• USFW Year: 1989
• USFW - Doc Type: Lifeline of the American Southwest
• Copyright Material: YES

The Colorado River:
Lifeline of the American Southwest1

C. A. Carlson and R. T. Muth

Department of Fishery and Wildlife Biology and Larval Fish Laboratory,
Colorado State University, Fort Collins, CO 80523, U5A

Abstract

CARLSON, C. A., AND R. T. MUTH. 1989. The Colorado River: lifeline of the American Southwest,
p. 220-239. In D. P. Dodge [ed.] Proceedings of the Intemational Large River Symposium.
Can. Spec. Publ. Fish. Aquat. Sci. 106.

In less than a century, the wild Colorado River has been drastically and irreversibly transformed into
a tamed, man-made system of regulated segments. The pristine Colorado, characterized by widely
fluctuating flows and physico-chemical extremes, supported unique assemblages of indigenous flora and
fauna. Closure of Hoover Dam in 1935 marked the end of the free-flowing river. The system has since
become one of the most altered and intensively controlled in the United States; many mainstem and
tributary dams, water diversions, and channelized river sections now exist in the basin. Despite having
one of the most arid drainages in the world, the river supplies more water for consumptive use than any
river in the United States. Its biota is dominated by non-native organisms, and about one third of its native
fishes are threatened, endangered, or extinct. This paper treats the Colorado River holistically as an ecosys-
tem and summarizes current knowledge on its ecology and management. L.ittle has been published on
productivity and fisheries of the mainstream river.

Resume

CARLSON, C. A., AND R. T. MOTH. 1989. The Colorado River: lifeline of the American Southwest,
p. 220-239. In D. P. Dodge [ed.] Proceedings of the International Large River Symposium.
Can. Spec. Publ. Fish. Aquat. Sci. 106.

En moins d'un siecle, Ie cours sauvage du Colorado a ete irrevocablement et tres fortement modifie
en un systeme artificiel de tronl;ons a debit regularise. A son etat vierge, Ie Colorado abritait des
assemblages uniques d' animaux et de plantes indigenes; on y observait des fluctuations importantes du
debit et des facteurs physico-chimiques. Depuis l'achevement en 1935 du barrage Hoover qui a marque
la fin de l'etat sauvage du fleuve, Ie systeme est devenu l'un des cours d'eau les plus perturbes et
intensivement hamaches des Etats-Unis. II existe maintenant dans Ie bassin versant de nombreux barrages,
ouvrages de deviation et tronl;ons canalises dans Ie tronl;on principal et les tributaires. Malgre que son
bassin hydrographique soit l'un des plus arides du globe, Ie Colorado foumit un plus grand volume d'eau
a des fins de consommation que tout mitre cours d'eau americain. Son biote est compose en grande partie
d'organismes exotiques et environ un tiers de sa faune piscicole indigene est menacee, en danger de
disparition ou disparue. On presente une vue globale du Colorado a titre d'e~osysteme et on resume les
connaissances actuelles sur son ecologie et sa gestion. Peu de donnees ont etelpubliees sur la productivite
et les pecheries dans Ie tronl;on principal. !

Introduction only in the "gray" lit rature. This case history is intended
to introduce the reade to the Colorado River System, with
"In a little over two generations, the wild Colorado has emphasis on current Ii erature, including recent reviews by
been harnessed by a series of dams strung like beads on a Graf (1985) and Stan~ rd and Ward (1986a, 1986b, 1986c).
thread from the Gulf of California to the mountains of We have drawn upon bnly the most significant elements of
Wyoming. The living river that Powell knew has been sec- the extensive non-peer-reviewed literature.
tioned into placid desert lakes throughout much of its length,
and the river's primordial task of carrying the massif of the
Colorado Plateau to the sea, bit by grainy bit, has been inter-
rupted, and will remain interrupted for the lifetimes of our
children's children and beyond." - Watkins (1969).
Despite years of study, the Colorado River has rarely
been viewed holistically as an ecosystem (sensu Minshall et
aI. 1985), and much information on its biota is available

Description of the Basin

The Colorado heads on the Never Summer Range in
Rocky Mountain National Park, Colorado, and flows
2 320 Ian to the Gulf of California in Mexico (Fig. 1). The
Green River, which joins the Colorado in Canyonlands
National Park, Utah, originates in the Wind River Range of

'Contribution 33, Colorado State University Larval Fish Laboratory.

220