The Vast and Vital Drainage Basin of the Colorado River

Meander of the Colorado River; photo by CitizenFresh (deviantART).

The drainage basin of the Colorado River constitutes the 7th largest watershed in North America. Size estimates vary from source to source, but most describe it as being roughly 245,000 square miles. This area encompasses parts of Arizona, California, Colorado, Nevada, New Mexico, Utah, and Wyoming, as well as the Mexican states Baja California and Sonora. The majority of the basin is located in the arid Mojave and Sonoran deserts. Elevations range from sea level to well over 13,000 feet in mountainous regions of Wyoming and Colorado. The average height running across the basin is 5,500 feet.

Colorado River Reflections by papatheo (deviantART).

Climatic conditions vary widely across the watershed. The average monthly high is 77*F in the upper basin and 92*F in the lower basin. Temperature lows range from 25*F to 48*F. Annual rainfall averages around 6 inches, with 40 inches falling in certain portions of the Rockies and only 6/10 of an inch in parts of Mexico. The upper region normally receives rain and snow during the winter and early spring. Rainfall in the lower basin comes from the summer thunderstorms of the North American monsoons.

As of 2010, twelve million people lived in the area of the Colorado River basin. Las Vegas and Phoenix are the watershed’s largest cities. Other important population areas in the basin include Tucson in Arizona, Saint George in Utah, and Grand Junction in Colorado. The states in the basin are among America’s fastest-growing ones. The population of Nevada increased by 66% between the late 20th century and early 21st century. Arizona’s population grew by 40%. Working to protect the watershed of this particular region is an immense responsibility that requires the cooperation of many, precisely because there are many to protect.