An old article entitled Climate Change Impacts on the United States The Potential Consequences of Climate Variability and Change Overview: West, prepared by the U.S. Global Change Research Program's National Assessment Synthesis Team, has been re-emphasized with the publication of an article in The New York Times.

"The scramble for water is driven by the realities of population growth, political pressure and the hard truth that the Colorado River, a 1,400-mile-long silver thread of snowmelt and a lifeline for more than 20 million people in seven states, is providing much less water than it had," NYT reports.

Although industrial and commercial use of water accounts for only about one percent of water use in the Western United States, the region's population has quadrupled since 1950, with most people now living in urban areas. As such, once-predominantly rural states are now among the most urban in the country. The West's economy has evolved from one dominated by agriculture and resource extraction to one of mostly government, manufacturing and services.

With the exception of 2005, the runoff from snowmelt high in the mountains has been below average during the last seven years in the region. According to some long-term projections, the mountain snows that feed the Colorado River will melt faster and evaporate in greater amounts with rising global temperatures, providing stress to the waterway even without drought. This year, the spring runoff is expected to be about half its long-term average.

"The Western mountain states are by far more vulnerable to the kinds of change we've been talking about compared with the rest of the country, with the New England states coming in a distant second," Michael Dettinger, a U.S. Geological Survey research hydrologist who studies the relationship between water and climate, told The New York Times.

In response to water shortages and consequent intensified competition among users, major water projects are taking form. Some $2.5 billion in water projects are planned or under way in four states, the biggest expansion in the West's quest for water in decades.

California Gov. Arnold Schwarzenegger is promoting "a ballot measure in 2008 that would allocate $4.5 billion in bonds for new water storage in California," NYT reports.

Another project calls for a proposed 280-mile long pipe to bring water from northern Nevada to Las Vegas. The Southern Nevada Water Authority (SNWA) proposes to construct and operate the project to develop and convey approximately 200,000 acre-feet per year of groundwater from seven hydrographic basins in northern Clark, central Lincoln and eastern White Pine Counties. This water would serve SNWA purveyor members in the Las Vegas Valley and customers of the Lincoln County Water District. The project would encompass the construction and operation of groundwater production, conveyance and treatment facilities, as well as power conveyance facilities.

Elsewhere, a suggested reservoir north of the California-Mexico border could correct an inefficient water delivery system that allows excess water to flow to Mexico. There is quite a bit the two countries can do to improve their institutional arrangements for sustainable water resources management as they anticipate developments to the year 2020.

Federal officials in Yuma, Ariz., started up an idled desalination plant, partially to purify saline subsoil water to pass to neighboring towns. Some people see a practice of southern California urban governments paying farmers not to grow crops requiring irrigation as potentially expanding beyond their region. The amount of payment to the farmer equals the value of the crop when ready for harvesting.

In addition to these and conservation efforts to help reduce demand, the government lists some other ways to adapt to life with less water:

• Improved technology;
• Planting crops that demand less water;
• Pricing water at replacement cost;
• Flexibility to transfer water across basins and water users; and
• Integrating the use of surface and groundwater.

These and other adaptive measures — such as replacing pivot irrigation with drip irrigation — can also serve water managers under conditions of scarcity.

Due to the high capital investment and to the many technical features involved not only in the installation of a drip system, however, both environmental AND cost constraints will be an important consideration in building additional control or storage facilities, too.