Southwestern U.S. Aquifers Are Extremely Low, NASA Data Show

Groundwater reserves in the U.S. Southwest are severely low and prospects for their long-term viability are bleak as persistent drought continues to parch the land and prevent recharging, according to an assessment from NASA.

As shown in this map, many underground aquifers in the Southwest are extremely dry compared to average conditions over the past 60 years. Deep red areas on the map, such as in southern California and Nevada, depict aquifers that are so dry there’s less than a 2 percent chance they could have experienced such levels of drought-related depletion since 1948.

Although the Pacific Northwest is experiencing drought-related wildfires, aquifers in that region appear to be well-stocked, according to the map. The discrepancy is likely due to the long lag between dry conditions at the surface and depletion of groundwater reserves, researchers say.

This assessment, which NASA considers experimental, is based on observations of small changes in Earth’s mass and gravity field — features that are affected by the movement and storage of water.