THEY FLOODED THE EARTH, and the desert bloomed. Out of parched soil fertile fields miraculously appeared, and a Latter-Day Mesopotamia was born between the Middle Snake and Green rivers.

Inspired by Mormon experience and Mormon law, the federal government subsidized the greening of the rest of the arid West with one of the most ambitious public works projects in history. Los Angeles, California; Phoenix, Arizona; and Las Vegas, Nevada, owe their population and wealth to dams and water diversions that dwarf the technological grandeur of previous desert empires. As we moved the mighty rivers around, no source of liquid gold went untapped, not even the glacial melt of the Ice Ages that is stored in underground aquifers.

Where the water flows, people follow, populating the scorched earth with their offspring, their livestock and their settlements. Unlike the Paiute and the Shoshone, who migrated with the seasonal ebbs and flows, these immigrants stayed put. More came in one wave after another. And when the West became the place where the majority of Americans wished to live, the flow of human traffic intensified, and 10,000 years worth of groundwater was mined in a couple of generations.

Everyone is still thirsty; the farmers want water for their alfalfa, the fishermen for their trophy trout, homeowners for their golf-course lawns. But after six years of drought as severe as the drought that dispersed the environmentally savvy Anasazi, westerners may be in for a prolonged period of behavior modification therapy. Lake Powell and Bear Lake are running on half empty, dam releases and irrigation allotments have dwindled to a trickle of century-old agreements, and residents of Denver, Colorado, and Salt Lake City, Utah, are living with what's beginning to feel like permanent water restrictions.

"Urban Utah is a highly artificial environment, a green oasis in a dry sea that depends on the lifeline of piped water," says horticulturalist Roger Kjelgren of the Plants, Soils and Biometeorology Department in the College of Natural Resources. "We tried to change the environment but the environment can only be changed so much before it bites back. Right now it’s biting back."

"We don't like to think of ourselves as limited by natural resources, but at some point we will be, and we will have to make that transition," says Kjelgren's natural resources colleague, Chris Luecke, who heads the Aquatic, Watershed and Earth Resources Department. more