Water table aquifer beneath the Great Plains in the United States
Saturated thickness of the Ogallala Aquifer in 1997 after several decades of intensive withdrawals. The breadth and depth of the aquifer generally decrease from north to south.Regions where the water level has declined in the period 1950–2015 are shown in yellow and red; regions where it has increased are shown in shades of blue. Data from the USGSGroundwater withdrawal rates (fresh water, all sources) by county in 2000. Source: National Atlas
Large-scale extraction for agricultural purposes started after World War II due partially to center pivot irrigation and to the adaptation of automotive engines to power groundwater wells.[4] Today about 27% of the irrigated land in the entire United States lies over the aquifer, which yields about 30% of the ground water used for irrigation in the United States.[5] The aquifer is at risk of over-extraction and pollution. Since 1950, agricultural irrigation has reduced the saturated volume of the aquifer by an estimated 9%. Once depleted, the aquifer will take over 6,000 years to replenish naturally through rainfall.[6]
The aquifer system supplies drinking water to 82% of the 2.3 million people (1990 census) who live within the boundaries of the High Plains study area.[7]
^Rex C. Buchanan; B. Brownie Wilson; Robert R. Buddemeier; James J. Butler Jr. "The High Plains Aquifer". Kansas Geological Survey, Public Information Circular (PIC) 18.