Ground Water

One of our most valuable resources is
the water beneath our feet.

- Something you can’t see and may not even know is there!

Ground water is the part of precipitation that seeps down through the soil until it reaches rock material that is saturated with water. Ground water slowly moves underground, generally at a downward angle (because of gravity), and may eventually seep into streams, lakes, and oceans.

Most of the void spaces in the rocks below the water table are filled with water. But rocks have different porosity and permeability characteristics, which means that water does not move around the same way in all rocks. When water-bearing rocks readily transmit water to wells and springs, they are called aquifers. Wells can be drilled into the aquifers and water can be pumped out. Precipitation eventually adds water (recharge) into the porous rock of the aquifer. The rate of recharge is not the same for all aquifers, though, and that must be considered when pumping water from a well. Pumping too much water too fast draws down the water in the aquifer and eventually causes a well to yield less and less water and even run dry.

Ground water is an important natural resource, especially in those parts of the country that don’t have ample surface-water sources, such as the arid West. It provides about 38 percent of the water delivered by water departments for use in our homes, businesses, and industries and provides drinking water for the 99 percent of the rural population who supply their own water from their own wells.