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Roger Weller, geology instructor

Colorado River
Samantha Mickens
Physical Geology
Spring 2006

                                    The Colorado River

A Long History


            The Colorado River has been cutting its way through America into Mexico for nearly twelve million years.  One of the river’s original names was the Grand River until 1921 when the state of Colorado requested it be changed to The Colorado River.  The great river alternates between rapid sections and very calm sections and makes for an exciting adventure throughout the American southwest.  The river passes through Colorado, Utah, Arizona, Nevada and California.  This once wild waterway ranges in depths of 6 feet to as deep as 90 feet in some parts, with an average of about 20 feet. 


From Headwater to Mouth:  (1400 miles)

Map of the Colorado Watershed


1.       The river is supplied by ice that is formed in winter high atop the Colorado Rockies in Rocky Mountain National Park. 

2.       It moves through Kewuneeche Valley

3.       Into the Shadow Mountain Resevoir

4.       Into Lake Granby

5.       From there, it enters Gore Canyon

6.       Then flows through Glenwood Canyon

7.       Through Grand Valley into Grand Junction

8.       Through Aches National Park

9.       Through Horse Point State Park

10.   Into Canyonland National Park where it meets Green River

11.   Then flows into Lake Powell

12.   Turns at Horse Shoe Bend

13.   Into Lees Ferry

14.   Through Marble Canyon

15.   Into the Grand Canyon

16.   Where it flows into Lake Mead

17.   Then forms a portion of the boundary between Arizona, and Nevada as well as the boundary between Arizona and California

18.   At last, the lower course of the river (which no longer reaches the sea due to damming and irrigation canals) ends in Mexico near Sonora


The Taming of the Wild River

From the Hoover Dam


            Throughout the history of the Southwest, the Colorado River has decided the fate of the people in those regions by affecting the ecological systems on its banks and in it’s flood plains.  The need to tame this powerful river reached a heightened urgency after the flood of California’s Imperial Valley in the early 1900s.  Allocation of the river’s water is governed by the Colorado River Compact, which supplies water for agricultural and municipal purposes.  In fact, about ninety-percent of the river’s water is diverted for irrigation purposes in major cities such as; Los Angeles, San Diego, Phoenix, Tucson, Corpus Christi, and Las Vegas etc.  Amazingly, over 100% of the water in the Colorado has been allocated to several communities.  This water is supplied by a series of canals and 29 dams.

            The most famous dam on the Colorado River is the Hoover Dam ambitiously constructed in 1936.  At times, Lake Mead (located behind the Hoover Dam) holds enough water to supply the surrounding area for two years.  Afterward, the Glen Canyon Dam was constructed to prevent silt and sediments from building up behind the Hoover Dam.  Before the construction of the Glen Canyon Dam, the river moved around 500,000 tons of silt and sediment a day.  That sediment is now trapped in Lake Powell, and the once “red river” presently flows a bluish-green color. 

            There are less publicized dams along the Colorado River, such as the Parker Dam, Davis Dam, Palo Verde Diversion Dam and Imperial Dam in Southern, California. 


Effects of Engineering on the River


            Unfortunately, the many diversions on the river have had some negative effects.  For example, the river can no longer “clean” its shores and beaches in some regions to deposit fresh sand in the inner canyons.  The water, which passes through three major deserts, has cooled from an average temperature of about 80 degrees Fahrenheit to around 40 degrees Fahrenheit.  This decrease in temperature has caused the extinction of several species of native fish.  Also, the Colorado River Delta in Mexico is deprived of silt and vital nutrients, which has changed a once lush environment to infertile land.  


The Future of The Colorado


            As the population in the southwest continues to grow, the future of the Colorado becomes less certain.  With a reduction in the quality of the water tapped from the Colorado the cities in this arid region must consider the effects on crop production and the vitality of their communities.  Will there be enough water to sustain all the cities, which rely on the river?  Only time will tell.  For now, these communities must consider alternative water supplies and devise a plan for a more reliable water source in the future. 


All photos courtesy of


Related Links: 
The Grand Canyon Explorer

The Colorado River


Desert USA: The Ultimate Desert Resource

Photo of Colorado from Space


Wikipedia:  The free Encyclopedia



Sharing Colorado River Water: History, Public Policy

 and the Colorado River Compact by Joe Gelt


Hoover Dam


Copyright (c)  2006 Samantha Mickens.
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.2
or any later version published by the Free Software Foundation;
with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.
A copy of the license is included in the section entitled "GNU
Free Documentation License".