Farmers are slowly drying up the nation’s largest underground source of fresh water.

Hydraulic pumps and mechanized irrigation equipment gave America’s Great Plains farmers access to seemingly limitless subterranean water wealth: the Ogallala Aquifer.

Six decades have passed, though, since grain growers and cattle producers began tapping the aquifer with such sustained thirst that they drew more water to the surface each year than flows in the Colorado River. Yet, what they pump in feet, Mother Nature returns to the ground in inches. The Ogallala is a finite water source.

Now the eight-state, $30 billion agriculture and livestock industry that has relied on the aquifer for its own wealth and to produce one-fifth of the nation’s corn, wheat, and cattle faces a new era of reckoning: how to reduce their unsustainable demands on the aquifer while maintaining an agricultural economy.

Map: The Ogallala Aquifer: A Freshwater Bonanza in Decline. Click image to enlarge.

This map was created by graphic designer Erin Aigner, with research assistance from Brett Walton of Circle of Blue. Choke Point: Index is an investigation into the precarious condition of water in America’s farm regions.