Sole Source Aquifer Protection Program

What's an Aquifer?

In one form or another, water occurs practically everywhere on the Earth. It occurs in the atmosphere as water vapor, clouds and precipitation. On the Earth's surface, it is found in streams, lakes, ponds, and oceans, as as a solid, water exists in the form of glaciers and the polar ice caps. Water is also found underneath the ground surface.

Ground water plays an integral part of the hydrologic cycle, sometimes called the water cycle, because it is a way in which the Earth stores fresh water. Water is continually evaportated from the land surface and oceans into the air to form clouds. The clouds drop their moisture back onto the land surface and oceans in the form of precipitation (rain, sleet, snow). The water that falls on the land surface has two ways of traveling. Water can flow on the land surface by gravity into streams, lakes, or rivers, and eventually back to the ocean, where the cycle starts all over again, or the water seeps or infiltrates into the ground through the soil, streambeds, the forest floor, or your back yeard, to become ground water. Ground water which is found in a permeable rock layer is called an aquifer. Aquifers are valuable as a source of drinking water, irrigation water, and to base flow to streams, rivers, and lakes.

Safe Drinking Water Act

The Safe Drinking Water Act authorizes EPA to designate aquifers which are the sole or principal source of drinking water for an area. To meet the criteria for designation, a sole source aquifer must supply at least 50 percent of the drinking water to persons living over the aquifer and there can be no feasible alternate source of drinking water. Once designated, EPA can review proposed projects that are to receive federal funds and which have the potential to contaminate the aquifer.