Like all other industries, mining corporations need water to make bare rock give up its valuable minerals. Mining water use is water for the extraction of minerals that may be in the form of such solids as coal, iron, sand, and gravel; such liquids as crude petroleum; and such gases as natural gas. The category includes quarrying, milling (crushing, screening, washing, and flotation of mined materials), re-injecting extracted water for secondary oil recovery, and other operations associated with mining activities.
For 2000, withdrawals were an estimated 137,000 million gallons per day (Mgal/d), or 153,000 thousand acre-feet per year. Irrigation withdrawals were 40 percent of total freshwater withdrawals and 65 percent of total freshwater withdrawals for all categories excluding thermo-electric power. Surface water accounted for 58 percent of the total irrigation withdrawals. About 61,900 thousand acres were irrigated in 2000. Of this total acreage, about 29,400 thousand acres were irrigated with surface (flood) systems; 28,300 thousand acres with sprinkler systems; and 4,180 thousand acres with micro-irrigation systems. Application rates were calculated by dividing total withdrawals by irrigated acres. The average application rate was 2.48 acre-feet per acre for the United States.
For 2000, an estimated 3,490 Mgal/d, or 3,920 thousand acre-feet per year, were used. Mining withdrawals were nearly 1 percent of total withdrawals and less than 2 percent of total withdrawals for all categories excluding thermoelectric power. Ground water was the source for 58 percent of total withdrawals for mining. Most of the ground-water withdrawals for mining (62 percent) were saline, and most of the surface-water withdrawals (85 percent) were freshwater. Saline ground-water withdrawals and fresh surface-water withdrawals each represented 36 percent of the total withdrawals for mining.
[D] - Data table for the pie chart are available.
Note: For 2000, the estimate of mining water use for the United States was based on estimates of total withdrawals for mining in 22 States, rather than on estimates from all States. These 22 States included the 12 States with the largest mining withdrawals during 1995, and 10 other States in which mining water-use data had been collected as part of a broader State water-use program for 2000. The 22 States that reported for 2000 accounted for 83 percent of the total mining water withdrawals during 1995. During 1995, withdrawals for mining accounted for a small percentage of the total water use, less than 1 percent of the total water withdrawals for all categories.
Mine drainage is formed when pyrite, an iron sulfide, is exposed and reacts with air and water to form sulfuric acid and dissolved iron. Some or all of this iron can precipitate to form the red, orange, or yellow sediments in the bottom of streams containing mine drainage. The acid runoff further dissolves heavy metals such as copper, lead, mercury into ground or surface water. The rate and degree by which acid-mine drainage proceeds can be increased by the action of certain bacteria. Acidic, metal-laden drainage from abandoned coal mines can have substantial effects on aquatic resources. Problems that can be associated with mine drainage include contaminated drinking water, disrupted growth and reproduction of aquatic plants and animals and the corroding effects of the acid on parts of infrastructures such as bridges. As with any enviromental damage, there are costs associated with trying to come up with a solution to the problem. In the Appalachian region of West Virginia, for example, the cost of correcting acidic mine drainage-related problems with currently available technology is estimated at $5–$15 billion.
Sources and more information
• Mining water-use for year 2000, USGS Circular 1268
• Estimated Use of Water in the United States in 2000, USGS Circular 1268
• Mine Drainage, USGS
U.S. Department of the Interior | U.S. Geological Survey
URL: http://ga.water.usgs.gov/edu/wumi.html
Page Contact Information: Howard Perlman
Page Last Modified: Friday, 07-Nov-2008 15:47:12 EST
