Up until the 1970s, most economists would have accepted Marx's description of capitalism as "the subjection of nature to man," but we have learned over the last three decades that nature is capable of fighting back. Oil, once thought to be limitless in supply, is steadily running out; and the consumption of fossil fuels has led to acid rain and global warming. And then there is water, which, next to the air we breathe, is the most important of all natural resources. Unlike oil, it is not running out, but it is not as plentiful in some places as in others. And as the demand for it rises--whether for agriculture, industry, or public consumption--some regions of the world will witness intense conflict over how it is allocated. One of these is the Colorado River Basin, which includes much of Wyoming, Utah, Colorado, Nevada, Arizona, New Mexico, and Southern California. As a forthcoming report from the National Academy of Sciences makes clear, it is facing a water crisis that will threaten its residents' way of life.

The Colorado River originates in the mountains of Wyoming, Colorado, and Utah; it flows south along the border of Arizona, Nevada, and California (with branches eastward toward New Mexico) and eventually flows out to sea in the Gulf of California. Since the beginning of the last century, the states in this region have been squabbling over water rights. The result has been a body of agreements, compacts, and court rulings, beginning with the 1922 Colorado River Compact, called "the Law of the River." But these agreements were forged when the river still supplied a surplus of water. According to the report, "the quantity of water allocations under the Law of the River already exceeds the amount of mean annual Colorado River flows." As a result, the law will have to be substantially revised over the next decades, as the region faces an unprecedented challenge from two directions.

First, the region continues to experience accelerating demand for water as new residents flock to places like Phoenix, Arizona and Las Vegas, Nevada. Of the five states that experienced the fastest rate of population growth from 1990 to 2000, four--Nevada, Arizona, Colorado, and Utah--are in the Colorado River Basin; and another Basin state, California, experienced the largest growth in total population. Each new resident in these states requires about 140 gallons of water a day, not simply for personal consumption, but to maintain an urban or suburban way of life. From 1985 to 2000, water consumption in Nevada's Clark County, home to Las Vegas, doubled.

Second, the supply of water in the region may actually be going down--most immediately, because of a continuing drought, but over the long run because of global warming. Rising temperatures cause water to evaporate. "The body of research," the National Academy concludes, "collectively points to a future in which warmer conditions across the Colorado River region are likely to contribute to reductions in snowpack, an earlier peak in spring snowmelt, higher rates of evapotranspiration, reduced late spring and summer flows, and a reduction in annual runoff and streamflow." At the same time, rising temperatures increase the overall demand for water for agricultural and public consumption. So the region is facing a severe supply-demand crunch.

Various measures are already being taken to reduce demand or increase supply. These include new technologies to conserve water, underground storage, desalinization plants, and, as any tourist to the region will quickly learn, popular education in limiting water use. (At a restaurant in Denver, Colorado one has to ask for water.) Tradeoffs are also being negotiated between cities and farms, which take a large proportion of the water for irrigation. Recently, California's Imperial Valley ceded some of its water to San Diego. But the report contends that these measures will either be of dubious value (as in the case of replacing farms with suburban sprawl) or insufficient. "Technological and conservation options for augmenting or extending water supplies--although useful and necessary--in the long run will not constitute a panacea for coping with the reality that water supplies in the Colorado River Basin are limited and that demand is inexorably rising."

What then to do? The report predictably recommends a "comprehensive, action-oriented study of Colorado River region urban water practices and changing patterns of demand." That's what one would expect from academics. But one cannot read the report without imagining a darker scenario--one in which desert cities like Phoenix and Las Vegas, which were built largely for tourism and leisure, will eventually go the way of the gas-guzzling Concorde. They will be victims of capitalism's unsuccessful attempt to subdue nature, while older cities like Cleveland--once termed "the mistake by the lake"--may have the last laugh.

John B. Judis, a senior editor at The New Republic, has been a contributor since 1982. He received his B.A. in 1963 and his M.A. in 1965 from the University of California at Berkeley. An active member of SDS and the left of the Sixties, he taught philosophy at Berkeley and at the San Francisco Art Institute.