Big Splash in the Arid West

It ranks along with the Grand Coulee and Hoover dams as one of the century's costliest and most complex public works projects. It carries a price tag of $1.3 billion and has been a building for twelve years--so far. It will not be fully operational until the early 1990s, probably at the cost of another $2.3 billion. But when Interior Secretary Donald Hodel and Arizona Governor Bruce Babbitt switched on the huge pump of the Hassayampa water plant last Friday, dedicating the mammoth Central Arizona Project, they signaled the opening of a new and possibly contentious era throughout much of the West. Within the next few months, the maze of aqueducts, pumping stations, tunnels, siphons and control gates now stretching 198 miles across Arizona's desert will change the way the region manages, and divvies up, its vital water resources.

The CAP system is an engineering marvel of the first order. It is designed to move precious Colorado River water, at the rate of more than 10 million cu. ft. per hour, from Lake Havasu on the California border southeast across the state to the expanding population centers of Phoenix and Tucson. A series of 14 pumping stations will force the water through a seven-mile tunnel in the Buckskin Mountains and lift the load 2,900 ft. over the course of a seven-day journey. The flow is monitored by a Modcomp JC 5000 computer situated in CAP headquarters near Phoenix, where controllers keep track of the system's operations on a 30-ft.-wide lighted map. In case of a rupture caused by an earthquake, or other serious trouble, the canals can be shut down in minutes.

Not since the building of the Alaska oil pipeline has a construction project posed more daunting challenges. In parts of the desert where daytime temperatures reach a scorching 120° F, work shifts began under lights at midnight, and liquid nitrogen was used to cool some of the 2.1 million cu. yds. of concrete poured. To allay environmental concerns, engineers built walkways across parts of the canals for the use of cattle and mule deer, and aqueduct sides were deliberately made rough to lend footing for smaller animals that might climb down for a drink. Human visitors are not welcome, but the outstretched ribbon of water has already inspired one desert sportsman to use the canal as a water-ski run.

For Arizona, CAP provides an alternative to a well that is steadily going dry. Long dependent on aquifers for most of its water, the rapidly growing state has been depleting its underground supplies twice as fast as they can be replenished. CAP's annual gush will eventually furnish Arizona with some 1.5 million acre-feet of water (one acre-foot is the amount needed to inundate one acre to the level of a foot and is roughly the quantity used annually by a family of four). Babbitt, who is fond of calling CAP his state's "last water hole," likens the effect of its start-up to the arrival of the first transcontinental railroad in 1882. Says Don Anderson, the project's chief engineer: "Without it, growth in Arizona would have to stop."