The Story of Water in Arizona: SRP and CAP Canals

The story of water in Arizona is something of an epic tale, but despite the feats of engineering that make cities like Phoenix possible, most people take water for granted. But the tale of Phoenix’s water starts in ancient times, when Hohokam people built an irrigation network throughout the Valley of the Sun, and it was this innovation that allowed them to thrive in the midst of the desert for over 1,000 years. Four centuries after their disappearance, American pioneers followed a gold rush into Arizona, and following in the footsteps of a man named Jack Swilling, people started using the old Hohokam canals as a foundation for their own. Private canals thrived in the Phoenix area until a major drought took place in the 1890s, and the Salt River failed to provide enough water on its own for the people of the budding city. At this time, it was determined that a dam needed to be built on the river. However, it was not until the National Reclamation Act was passed that the state could get the project properly funded, and built the Theodore Roosevelt Dam. This project also including a major effort to improve the private canals that had been built over the years, and to bring them under the central control of the Salt River Valley Water User’s Association (currently a part of the Salt River Project or SRP).CanalMap2012 Now, there are 131 miles of main canal in the valley, and the structures are a common sight throughout the city. They not only provide precious water, but recreational activities as well, as many of the city canals have open walkways along them for people out walking, running, or biking.

As much of an engineering feat as the SRP canals are, however, Arizona has an even more magnificent canal system to its name, the CAP or Central Arizona Project canal which is the largest canal system in the United States. Stretching for 336 miles across the state, the CAP canal brings Arizona’s allotment of the Colorado River water down to Phoenix and Tucson. The 3.6 billion dollar project was officially started at Lake Havasu in 1973 and took 20 years to complete. Phoenix now combines the use of SRP, CAP, and ground water as its population grows ever larger. But the CAP has done more than just change the urban landscape, it has altered the ecology of the desert.

(c) A.B. Raschke
(c) A.B. Raschke
Whereas rivers concentrate the flow of water from run off and streams, and then take that water to the sea, canals do just the opposite. They take water away from lakes and rivers, spreading them ever thinner over the landscape until individual people are able to make use of the water. Canals also run across topographic gradients as opposed to rivers which run down them, and this too makes a difference in the desert landscape because canals interrupt natural flows of water, sometimes creating oases and other times cutting of the land from flows of rain water which once supported wash ecosystems.

Whatever way that you look at it, the story of water in Arizona is one of ingenuity and risk, and the evidence of age old, monumental efforts to shape the desert is all around us. The canals are an understated aspect of our city, and our state, but they should remind Arizona’s residents and visitors just what it takes to build cities in the desert.

(c) A.B. Raschke
(c) A.B. Raschke

SRP Canals
Central Arizona Project


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