The Arid West—Where Water Is Scarce - Water In The West—liquid Gold

The United States is a nation relatively rich in water resources. According to the U.S. Geological Survey's Estimated Water Use in the United States in 2000 (the latest data available), in the lower forty-eight states the total renewable supply of water is about 1,400 billion gallons per day. Nevertheless, while the nation as a whole is water-rich, this abundance is not spread evenly throughout the country. Some areas have more water than others, while some have a higher need than others. Those with the greatest need do not always have adequate water resources, a situation that can lead to serious problems and conflicts.

The American West is arid (characterized by desert land) and semiarid (prairie land), with limited and inconsistent supplies of water. From the Rocky Mountains, which form the Continental Divide, to the shores of California, lay the dry basins and deserts of the vast western region of the country. Some sources consider the threshold of the "Great American Desert" roughly at the hundredth meridian, where the landscape turns from green to brown. (A meridian is an imaginary line drawn from the North Pole to the South Pole and numbered according to the degrees of longitude. In this case, the hundredth meridian runs approximately from the central Dakotas through Abilene, Texas.)

Of the 1.9 billion acres of land in the lower forty-eight states, almost half are in the semiarid and arid regions, which receive less than twenty inches of precipitation per year. The small amount of rain and snow that falls is unevenly distributed. For example, Flagstaff, Arizona, receives more than twenty inches a year, but in Phoenix and Tucson, where most of Arizona's people live and most of the agriculture is located, the yearly rainfall averages barely nine inches. The reason for this is the North Pacific high pressure system. This is a huge zone of high atmospheric pressure that is the characteristic weather pattern for the Pacific Ocean off the coast of North America. The North Pacific High shoves virtually all precipitation toward the north.

No resource is as vital to the West's urban centers, agriculture, industry, recreation, scenic beauty, and environmental preservation as water. Throughout the history of the West, especially in California, battles have raged over who gets how much of the precious resource. The fundamental controversy is one of distribution, combined with conflicts between competing interests over the use of available supplies.