Deep in the delta of the Colorado River, the Cocopa people have fished and farmed for perhaps 2,000 years. They once harvested a grain they called nipa, a unique salt-loving plant known to botanists as Distichlis palmeri that tastes much like wild rice. Protein was also abundant: they sometimes ate fish three times a day, and they hunted deer, wild boar, ducks, and geese. Known as "people of the river," the Cocopa had no formal calendar but keyed their lives to the Colorado's seasonal floods. While no census documented their numbers, historical accounts suggest that about 5,000 Cocopa were living in the delta 400 years ago.

Today the Cocopa culture is at risk of extinction. Their water has been siphoned away from the Colorado to fill swimming pools in Los Angeles, generate electricity to illuminate Las Vegas, and irrigate crops in the deserts of Arizona, California, and Mexico's Mexicali Valley. Fishing and farming can no longer sustain them. They last harvested nipa in the early 1950s; by then, U.S. dams upstream had largely eliminated the annual floods that had naturally irrigated their staple grain. Now just 40 to 50 Cocopa families remain south of the border. With little means of subsistence or livelihood in the delta countryside, many of the tribal members have migrated to the cities. Anita Alvarez de Williams, a Mexicali-based expert on the Cocopa, worries that by the end of the twentieth century they "may no longer be river people at all."

It might be tempting to dismiss the Cocopa's plight as the price of progress. Supporting ever larger populations and higher levels of consumption has always involved taking more and more of nature's bounty, and those last in line are bound to suffer. But apart from the tragedy of losing yet another culture in a world of dwindling cultural diversity, the fading of the Cocopa people is a harbinger of far more widespread disruption to society at large today.

Indeed, a growing scarcity of freshwater is now an impediment to global future food security, health of aquatic ecosystems, and social and political stability. Each year, millions of tons of grain are grown by depleting groundwater, a clear case of robbing the future to pay for the present. Competition for water is increasing-between cities and farms, between neighboring states and provinces, and between nations-as demands bump up against the limits of a finite supply. And critical ecosystem functions such as flood protection, water purification, habitat maintenance, and the sustenance of fisheries are being destroyed by excessive damming, diversion, and pollution of rivers.