Ground Water Resources Program

(An excerpt from a Report to Congress on the Ground-Water Resources Program)

Ground water is one of the Nation's most important natural resources. Underground aquifers supply drinking water to about 130 million United States residents (about 50 percent of the population), and ground water is used in all 50 States. About 40 percent of the Nation's public water supply, and much of the water used for irrigation, is provided by ground water. About 42 million people, including most of the rural population, supply their own drinking water from individual wells.

Ground water also plays a crucial role in sustaining streamflow. During low-flow periods, most streamflow is derived from ground water. Ground-water pumping decreases the amount of ground water that flows to streams, or alternately, causes streams to seep to ground water. As a result, ground-water and surface-water users commonly compete for the same resource. Ground water also is vital to the health of lakes and wetlands. Moreover, plants and aquatic animals greatly depend upon the ground water that discharges to the streams, lakes, and wetlands in which they live.

(Above images from: A Report to Congress on Ground Water)

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References:

Portable Document Format (PDF) of report is at:

Grannemann, Norman G., 2001, U.S. Geological Survey Ground-Water Resources Program, 2001, USGS Fact Sheet 056-01 (2.19MB)

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Grannemann, Norman G. and Weaver, Thomas L., 2000. An Annotated Bibliography of Selected References on the Estimated Rates of Direct Ground-Water Discharge to the Great Lakes, US Geological Survey Water-Resources Investigations Report 98-4039