Most human and land-based animal and plant activities that use water require freshwater. In the vast majority of cases, saline or salt water cannot be used without treatment. Of the estimated 861 million cubic miles of water on the planet, barely 3% (twenty-six million cubic miles) is freshwater. If this water were distributed over the planet relative to population density and animal and plant nee…
Freshwater that is potable (suitable for human consumption) is the most crucial resource for the maintenance of human societies. Freshwater, however, is limited in total supply, unevenly distributed, and often of unacceptable quality, particularly in areas where the supply is limited. Most people in the United States obtain water through a utility company. These companies are called public water s…
For reporting purposes, water use in the United States is classified as in-stream or off-stream. In in-stream use, the water is used at its source—usually a river or stream—and the vast majority of the water is returned immediately to the source. Little or no water is actually consumed. Examples are hydroelectric plants where water flows through the generators and goes right back int…
The off-stream water-use categories described above are generally recognized as representing the most essential human uses of water. Sometimes there is not enough water available at a given location to meet all the demands for it. In those situations, who owns the water? Water rights are held in trust by the states and may be assigned to individuals and corporations according to statutes regulatin…
Since the enactment of the 1972 Federal Water Pollution Control Act, with its emphasis on maintaining the physical, chemical, and biological characteristics of the nation's waters, there has been an increasing awareness of the need to protect and maintain the insects, plants, and animals that make up the ecosystem of surface water bodies. Since life on Earth first began in the ancient seas,…
After continual increases in U.S. total water withdrawals since the USGS began reporting in 1950, water use peaked in 1980, declined through 1990, and has remained relatively stable since then. From 1995 to 2000 (the latest data available), a period that experienced a 7% increase in U.S. population, total off-stream water use increased only 2%. Water use for public supply increased by 8%, irrigati…
Although water itself can be neither created nor destroyed, its usefulness and availability can fluctuate dramatically. Both the quality and quantity of water resources need to be protected for the nation's present and future generations. Although current water use can be determined, total water needs for most uses are changing. Water use is dependent on prices, technology, customs, and reg…
As usable water becomes rarer because of increasing population and the pollution of water supplies, it is expected to become a commodity like iron or oil. Some experts have predicted that at some point water will be more expensive than oil. Of the 200 largest river systems in the world, 120 flow through two or more countries. All are potential objects of world political power struggles over this c…
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