Water and Asphalt: The Impact of Canals and Streets on the Development of Phoenix, Arizona, and the Erosion of Modernist Planning

Introduction

In the arid desert of the American Southwest, water is among the region's most valuable resources. Phoenix, Arizona, is a clear example of the importance of water as a life force and how it impacts the built form of Southwest cities. Invariably, the ability to move and store water shaped Phoenix from a small trading town in the middle of the desert to a true urban oasis of close to 4.5 million people.

The capacity of Phoenix and the region to provide and manage water—from the time of its founding in 1867 to today—has driven and continues to drive its growth and development. There is little question of the importance of water for human life or that the control and manipulation of water have been an ever-present challenge to urban development, but among some of our greatest accomplishments are the many complex and massive infrastructure projects that supply human populations with a reliable water supply. Urban life itself is predicated upon the supply, circulation, and elimination of water in a city.¹ In the case of Phoenix, it's very founding as a city and the development of the canals to control the area's water supply go hand in hand.

The area's canals are unique for a region known for its hot desert climate in that they do not fit the normal typology of canal cities. The canals in the Phoenix region are not industrial, nor do they provide transportation as they do in many other cities, yet they continue to serve as the driver of economic growth for the region. Additionally, while they started as a system for irrigating hundreds of square miles of desert, their primary purpose today is residential. Urbanization, economic development, the management of water, and the construction of canals have been integral to the growth of the Phoenix region. Without the canal system, the city would not have grown into the sprawling metropolis it is today. Thus, the canals in the Phoenix region are an ever-present reminder of the role of water in urban life.

The Phoenix metropolitan region contains hundreds of miles of canals, mostly designed for irrigation and human consumption, that divert water from rivers, streams and underground aquifers. At the time of their initial development, the main function of these canals, as noted, was for the irrigation of farmland—in essence as a tool for economic development of the area.² As the region grew rapidly in the post–World War II period, the use of water for agriculture shifted toward residential uses. Rapid urban, mostly suburban, growth in the decades after World War II necessitated the development of new canals to bring water for increased residential use and economic development. The impact of the canal system and water itself as an economic development driver is a key component of this. But more than that, the provision of water to a growing region has become an important part of the region's psyche, one that has undergone radical changes over the course of the 20th century into the 21st.

In the early 20th century, the canals remained an important part of the urban landscape and maintained important social functions. But the early 20th century was also marked by a desire to have ever-increasing control over the supply of water so that steady and predictable amounts of water could be provided. By the 1950s, the rapid development of the Phoenix area resulted in a change in the role that canals played. The post–World War II period began to treat the canals as mere infrastructure and the social and ecological roles of the canals began to break apart. This transition culminated in the approval of the massive Central Arizona Project (CAP) Canal in 1968, which would bring Arizona's 2.8 million acre-feet of water from the Colorado River to the urban areas of Phoenix and Tucson.³

By the time the CAP Canal was complete in the late 1980s...