THE water, sparkling pale-blue in a southern California swimming pool, may once have run down cold rivers hundreds of miles north of San Francisco, or fallen as snow in the Rockies to flow down the Colorado River. This water from afar lies behind much of the development in the western United States. To settle the dry region west of the 100th meridian, Americans have built the most extensive and far-flung waterworks projects in world history.
But the era of plumbing untapped water resources to flood new furrows or fill new faucets and swimming pools is nearly over, according to a wide array of Western water engineers, economists, political scientists, and environmentalists.
The coming era will be one of more efficiency and flexibility in managing an increasingly scarce, increasingly expensive commodity.
For nearly a century, water projects have been used as a federal subsidy of grand proportions for building a civilization, through irrigated agriculture, in the American Southwest. It has worked.
The Southwest contains many of the nation's largest and fastest growing cities. Irrigation has made California the nation's top agricultural producer, and it boasts many of the largest manmade water projects in the nation. Although the 17 Western states receive, on the average, less than 20 inches of annual rainfall, they account for 84 percent of all the fresh water used in the country.
But water is increasingly scarce in the Southwest, as the region runs out of inexpensive new water sources:
Denver predicts that by the end of next year it won't have enough water to add any new residential or commercial taps to its system.
Phoenix and Tucson are draining their underground water supplies and need to cut water use substantially.
In the panhandle region of Texas, farmers have emptied, by one half, the Ogallala. This is a massive aquifer that provides different regions of eight Midwestern states with the water they need to irrigate cotton and sorghum crops.
When the Central Arizona Project opens next year, southern California will lose roughly half the water it acquires from the Colorado River.
This makes San Diego, which imports 90 percent of its water and depends heavily on the Colorado, especially vulnerable to water shortages.
So, will the West have the water it needs to sustain its urban growth?
Most analysts believe it will. The deciding factor will be the future use and allocation of the 85 to 90 percent of water used for irrigation in the Southwest. Cutting back irrigation useage in many regions by even 10 percent -- through more efficient water practices or by allowing less-productive land to go fallow -- would double the water available for residential and industrial use.
``We're not facing a water crisis in the West, because what's gradually happening is we're taking water away from agriculture and shifting it to more urban uses,'' says Henry Caulfield, a political scientist at Colorado State University and former director of the US Water Resources Council.
A symbol of the times may be the current negotiations of a water deal between southern California's Metropolitan Water District (MWD) and the Imperial Irrigation District (IID), a desert farming region next to the Colorado River and Mexico. MWD will pay IID $10 million a year if IID agrees to line its dirt irrigation canals. IID would pass along the water saved -- estimated to be at least 100,000 acre-feet per year.
At $100 per acre-foot (roughly the amount of water a family of four uses in a year), this water would be far cheaper for urban southern California than the water it must pipe down from the north. And Imperial Valley farmers, who pay only $9 per acre-foot, would not lose any water they can afford to use.
Most analysts believe the days of expanding agricultural irrigation and huge water projects are over. Cities can pay more for water than farmers can, and cities produce a greater economic return on it than farms do. But farmers still have rights to most of the cheap water sources, and they still receive massive water subsidies from the federal Bureau of Reclamation.
Farms, paying a small fraction of the real cost of their water, often irrigate pasture or alfalfa for only a small return on mediocre land. They do this with water that nearby cities are desperate to buy.
Increasingly, residents of the Southwest talk about water as a commodity to be bought and sold. Treating water as a commodity allows the marketplace to more efficiently distribute water to the most productive uses.
Larry Michaels, general manager of San Diego County Water Authority, says that at $100 an acre-foot, water users all over the state are willing to sell. ``That's a very good number for creating a lot of water,'' he says.
The tangled web of water rights, rates, and agencies won't give way easily to free-market exchange of water, especially in California. Many, who are concerned about the impact on communities and agriculture, don't believe it should. The buying and leasing of water rights, however, is likely to help smooth the jagged edges of water distribution, which is often a cause of regional disputes.
The traditional way of solving water problems still runs strong here. The massive MWD in Los Angeles still hopes to finish the State Water Project by opening up more delivery capacity from northern California. Such proposals have been defeated twice in recent years by California voters and legislators.
The federal Bureau of Reclamation will complete the Central Arizona Project canal from the Colorado River to Phoenix and Tucson over the next few years. And a handful of other projects around the Southwest are moving toward completion. In addition, there are still some grand engineering visions of piping water from the Columbia River in the Pacific Northwest or even from Quebec to the sprawling Southwestern cities.
But virtually no one expects these visions will ever materialize. The good dam sites have been taken. Most of the entire West's water has been appropriated and accounted for. Federal funds for water projects are drying up. And environmentalists, opposed to big water engineering, have become more effective and active in touting the benefits of leaving water in its natural state.
``The whole concept has got to change in the West, to an economic and environmental view of water,'' says water engineer Victor Koelzer of Fort Collins, Colo. ``No doubt, irrigation was the lifeblood of the West when it was opening. But now it's open.''
Next: A dry future for cities like Tucson, Ariz.