Drawing too much water from aquifers “could lead to difficult choices affecting not only domestic food security but also international markets,” says a University of Illinois study of three over-pumped U.S. groundwater sources. Reliance on the aquifers – the Central Valley aquifer in California, the High Plains aquifer in the Great Plains and the Mississippi Embayment in the lower Midwest – increased so rapidly from 2003-08 that they accounted for 93 percent of total groundwater depletion in the country. Not surprisingly, the High Plains water was used mostly for grain. The largest share of Central Valley water was consumed by livestock. Some 91 percent of the groundwater “embodied” in products from the three regions stayed in the United States.
“The issue here is the tradeoffs,” said U-Illinois professor Ximing Cai. There are tradeoffs between current and future use or between environmental benefits and economic profits. Food supplies are affected by decisions about water use. Although exports accounted for a small share of water use, they hold a large market share in the countries that buy them so there is a long-distance impact.