Irrigation brought fat harvests to the plains. But the water is disappearing.

Industrial agriculture on the Great Plains began in the 1950s when mechanized pumps and sprinkler irrigation systems allowed trillions of gallons of water to be pulled each year from the Ogallala Aquifer, the primary water supply for parts of eight states.

The aquifer is slowly being pumped dry. Water wells, for instance, have dropped more than 61 meters (200 feet) in the Texas Panhandle.

Though the trend line is downward, not all regions are equally affected. As the map shows, there are peaks and valleys of saturation. Some areas have a few decades of water left, some more. For a few counties on the aquifer’s margin, wells are already spitting dust.

Map: The Shrinking Ogallala Aquifer 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.