We realize you might find this diagram conusing. This diagram uses a "cylinder" and "pipe" layout to show where our nation's water comes from, how it is used, and where it goes after use. A detailed explanation is given below the diagram. The data for this chart is from U.S. Geological Survey Circular 1268, "Estimated Use of Water in the United States in 2000." (Note: Figures in the diagram are rounded.)
The top row of cylinders represents where America's water came from (source) in 2000, either from surface water or from ground water. You can see most of the water we use (262,000 million gallons per day (Mgal/d)) came from surface-water sources, such as rivers and lakes. We used about 83,400 Mgal/d of ground water (from wells).
The pipes leading out of the blue and brown cylinders on the top row show where the water was sent after being withdrawn from a river, well, etc. For example, the blue pipe coming out of the surface-water cylinder and entering the Public supply grey cylinder shows that 27,300 Mgal/d of water was withdrawn from surface-water sources for public-supply uses (you probably get your water this way (please fill out our survey)). Likewise, the brown pipe shows that public-suppliers withdrew another 16,100 Mgal/d of water from ground-water sources.
Each green cylinder represents a category of water use. The Industrial cylinder, for instance, shows how much water the United States used, each day, by industries. In 2000, about 18,500 Mgal/d of water was used for industrial purposes, with about 14,900 Mgal/d coming from surface water and about 3,570 Mgal/d coming from ground water.
So, now you maybe see how the two "Source" cylinders on the top row show how much water was withdrawn from the environment, and, for each water-use category (the green cylinders), the water arrives via the pipes.
Confused about Mgal/d? Find out how much a million gallons is.
U.S. Department of the Interior | U.S. Geological Survey
URL: http://ga.water.usgs.gov/edu//summary95.html
Page Contact Information: Howard Perlman
Page Last Modified: Wednesday, 13-Aug-2008 07:22:16 EDT
