Groundwater is one of the Nation’s most valuable natural resources. It supplies the drinking water for nearly half our nation’s population and provides about 40 percent of our irrigation water. It sustains streamflow between precipitation events and during protracted dry periods. And it helps maintain a variety of aquatic ecosystems that are dependent on groundwater discharge to streams, lakes, and wetlands. As the Nation’s principal reserve of freshwater, it represents much of the potential future water supply.
Groundwater: right underneath our feet
Groundwater is an essential part of most of our daily lives. Rural farmers and urbanites, water-supply managers and regulators, researchers and policy-makers — all have a part to play in the current status and future of our groundwater resources. This valuable resource is right underneath our feet.
While groundwater can be found nearly everywhere, its availability varies. Groundwater is stored in aquifers, a resource shared by many users. Aquifers receive water deposits from precipitation and surface water. If there are too many users making too many withdrawals from an aquifer — say, to irrigate farmlands, water lawns, or supply wells — and the deposits don’t keep up with the demand, there may not be enough groundwater to go around.
In many states, groundwater is a vital source of irrigation water for farmers. USGS photo.
Even when groundwater is plentiful, it’s not truly available unless the quality is acceptable for the intended use. Both water quantity and quality are essential to maintaining water supply for municipal, domestic, agricultural, and recreational use, and for aquatic ecosystems.
USGS and groundwater
At the USGS we systematically observe and monitor groundwater conditions at locations across the United States. USGS groundwater assessments help inform the public so that citizens across the nation can engage in best practices for management, protection, and conservation. Groundwater conservation is a matter of both conserving the quantity and protecting the quality from contamination.
USGS personnel operate a drill rig to assess groundwater conditions. USGS photo.
USGS scientists work constantly to improve our understanding of how groundwater moves through the subsurface and what human and natural factors affect the quantity and quality of that groundwater. Understanding these dynamics helps answer important questions about current groundwater availability and long-term sustainability