The Colorado River in the Grand Canyon

Abstract

OR the past three summers, as a biologist interested in ecology, I have been rafting through the upper 185 miles of the Colorado River in the Grand Canyon with classes from the University of Northern Colorado and Anderson University. During these trips we have studied the ecology and geology of the Grand Canyon and the Colorado River, and I have become increasingly aware of the pressures placed on the ecosystem by the number of people rafting on the river, the presence of Glen Canyon Dam and the recent unusual worldwide weather patterns. This has caused me to wonder what changes might be taking place in this ecosystem. Water quality usually is a good measure of the health of an ecosystem; consequently, I began to measure factors such as dissolved oxygen, total dissolved solids, turbidity, pH and temperature to see if changes are taking place in the Grand Canyon ecology. The Colorado River flows from the Rocky Mountain National Park region in north central Colorado westward through Colorado and the southeastern corner of Utah, across northern Arizona and then south along the western border of Arizona to the Gulf of California. Perhaps the most rigorously protected portion of this river and its adjacent riparian communities is the 255-mile stretch between Lake Powell and Lake Mead, the portion that meanders through the Grand Canyon. The magnificence of the Grand Canyon is often beyond description. The nuances of the play of light along the canyon walls at dawn and dusk, the sounds of the rushing water and the song of the Canyon wren, and the earthy smells cannot fully be described in this manuscript; they must be experienced. The river is constantly changing; just when you think you know what to expect, a new experience awaits you. Major John Wesley Powell, one of the earliest explorers of the Colorado River and the Grand Canyon, described the Grand Canyon as follows: