The culprit is the recent widespread use of groundwater for irrigation of crops. Starting in the 1940s, crop irrigation from wells became practical and widespread, and many farmers switched to high-value, water-thirsty crops like corn instead of crops that relied on natural rainfall. By 1990, about 95% of all water being drawn from the High Plains aquifer was for irrigation, according to a U.S. Geological Survey report. As a result, there has been a decline in the production of many wells. And once the groundwater is depleted, it could take decades or even hundreds of years to replenish it.
Farmers in the area are well aware of the problem, but there is essentially no easy solution. Some farmers have abandoned once-productive fields. Others have switched to less water-thirsty crops like milo or cattle, in the hope of continuing to farm for awhile longer. In the long run, the Midwestern states that have depended on the High Plains aquifer will have to learn to get by with less groundwater than in the past.
The problem of maintaining adequate supplies of freshwater is, of course, worldwide. As water gets scarcer, efforts to conserve it will only intensify.