Groundwater Answers

Groundwater is the largest reservoir of readily available freshwater on Earth; it supplies nearly half of all drinking water in the United States, supports crop irrigation, maintains stream base flow, and is a critical buffer during droughts.

Groundwater overdraft occurs when the rate of pumping from an aquifer exceeds its natural recharge rate. Likely consequences include falling water tables, dry wells, land subsidence, reduced stream flow, and saltwater intrusion in coastal areas.

In the United States today, groundwater is used primarily for irrigation (about 70%), public drinking-water supply, and industrial and thermoelectric power uses.

Groundwater use has increased because of population growth, expanded irrigation for food production, industrial development, and the need for reliable year-round water supplies in growing urban areas.

In preindustrial times, groundwater was used mainly for small-scale domestic wells and limited irrigation. In industrial times, large-scale pumping supports cities, factories, and extensive agriculture, often exceeding recharge rates.