I wrote earlier about the groundwater overdraft in Yemen, which was largely due to irrigated farming (specifically for qat, a mild stimulant). I sort of brushed off the idea that the Ogallala aquifer was drying up. But, researchers recently used satellite data to show that yes, it is drying up, and at an alarming rate. In the southern portions, the aquifer may be unable to support irrigation as soon as 30 years from now. The northern portions seem to be holding steady in water level, due to rainfall and infiltration from lakes, so only Kansas and Texas would be affected. The same study showed that groundwater tables fluctuate widely in California’s Central Valley, although a clear decline is not evident. These are major farm belts in the US, and the loss of irrigation water would be, quite simply, devastating for those areas. We would do well to take heed and adopt proper policy measures to sustain these critical but not unlimited water resources.