Senator Eliot Shapleigh - El Paso, Texas

Americans don't like to be told that there's anything they cannot do. Or subdue.

The indomitable American spirit, coupled with ingenuity, has made the Southwest the fastest-growing region of the country. The arid landscape has been made habitable in large part because engineers figured out how to manipulate water from the Colorado River to irrigate the lawns of San Diego and the golf courses of Scottsdale as well as supply the needs of other vast man-made oases.

God made the desert Southwest; Americans made Las Vegas.

But now, if a report from the nation's most influential scientific research body is on target, the victory of man over nature there may prove short-lived.

The National Research Council warns the tens of millions of people who depend on the Colorado River and its basin for water – including residents of booming Arizona, New Mexico, Nevada, Colorado and southern California – that the drought conditions they've experienced over the past few years are closer to the historic norm than previously understood. Moreover, global climate change will further reduce the river's flow.

With its rapid population growth, the Southwest is looking at critical water shortages over the long run – and scientists say that technological advances and conservation measures will not be sufficient to cope. Researchers forecast "increasingly costly, controversial and unavoidable trade-offs among water managers, policymakers and their constituents."

The comprehensive report has stark policy implications for the region. Arizona's population has grown 40 percent since 1990, for example, and Colorado's has expanded by comparable numbers. Nevada's population has almost doubled in that time.

All of that incredible growth is now at risk. Development and migration patterns – both of Americans relocating to the Southwest and foreigners coming over the Mexican border and settling there – will be a significant challenge to natural resources.

Though North Texas is in better shape on water matters than our neighboring states to the west, we have to learn from their experience. The Dallas-Fort Worth region is projected to grow substantially in decades to come. Far-sighted lawmakers and civic leaders must make provisions now – while there is time – if only as a matter of protecting our prosperity.

There is still much that scientists don't know about climate and water supply, particularly with the global climate upheavals now under way. This is even more reason why we need strong planning and conservation.

The larger lesson for all Americans in the water crisis now enveloping the Southwest is this: Contrary to what the transformative power of wealth and technology has taught us in recent decades, there are natural limits to what humankind can do.

The American ideal of freedom has always entailed the romantic notion that if you can dream it, you can make it happen. To this conviction we owe many of this nation's most spectacular achievements, including making great cities arise out of the frontier deserts.

Yet perhaps the next great American frontier to conquer is inward: learning how to discipline ourselves to live within our means.