Groundwater depletion could threaten "national food production capacity" and the future of farming in the southwest of the United States, a NASA scientist and other experts told Newsweek. Mary Michael O’Neill, a research scientist at NASA, is the lead author of a September study in Proceedings of the National Academy of Sciences (PNAS), which found that aquifers—rock layers holding water that serve as a key source of freshwater—are being “depleted faster than they recharge” in the southwest of the U.S. The recent study assessed global terrestrial water storage (TWS) trends from April 2002 to November 2025 using satellite data from NASA.
TWS refers to all water on the surface of the land and in the subsurface, including surface soil moisture, root zone soil moisture, groundwater, snow, ice, water stored in the vegetation, rivers, and lake waters. Aquifers in the southwestern U.S. have long been documented as “unsustainably depleted,” O’Neill told Newsweek, and the findings of the latest study are consistent with decades of prior research showing “these aquifers are being depleted faster than they recharge,” she added. The NASA scientist warned: “Continued depletion at these rates threatens the long-term viability of irrigated agriculture in these regions, along with the rural economies and food production that depend on them, and risks pushing farmers toward deeper, costlier wells.” The study's main takeaway is that “human activities, particularly irrigation and groundwater pumping, are a measurable and pervasive driver of water storage change across the world,” and “the most severe losses are often more localized than earlier, coarser methods could detect,” O’Neill said.
NASA’s Gravity Recovery and Climate Experiment (GRACE) and its Follow-On successor (GRACE-FO) use precise satellite data to quantify tiny shifts in Earth’s gravity field, from which redistributions of mass in the atmosphere, oceans, and continents can be inferred. The recent study used an innovative GRACE/FO processing method to spatially refine global TWS trends. O’Neill told Newsweek: “Our method adds spatial precision in that we can localize losses to specific portions of aquifers.
That precision can help direct monitoring and management, but it doesn’t change the underlying conclusion that current groundwater use in these regions is not sustainable long term.” Globally, groundwater depletion was found to be “more intense and localized than earlier gravimetry estimates suggested,” O’Neill said, adding that “this effect of signal attenuation varies spatially.” Prior assessments and data processing methods of the aquifers in California's Central Valley and the High Plains reported depletion rates that broadly agreed with the results of the recent study, “although our rates were slightly higher,” O’Neill said, noting, “instead, we show more precisely where the depletion we already knew about is concentrated.” One notable result from the study that’s specific to the U.S. is that land equipped for groundwater irrigation had the statistically strongest relative influence on water storage trends in non-polar North America, O’Neill said, explaining that “this is out of 10 variables tested, five representing human land and water use and five representing climate, including precipitation trends and anomalies.” She noted: “This could imply that groundwater pumping for agriculture in the U.S. was a stronger driver of long-term freshwater storage loss even than precipitation.” Sustained aquifer depletion in major U.S. agricultural regions, such as the Central Valley and the High Plains, carries several risks, O’Neill warned, noting that these areas supply a large share of U.S. produce, grain, and livestock feed. She explained that “continued depletion threatens national food production capacity and could shift agricultural output, and the economic activity tied to it, toward other regions or imports. Falling water tables also raise pumping costs, which squeezes farm profitability and can accelerate consolidation or abandonment of smaller operations.” In regions such as the Central Valley, continued groundwater depletion is also tied to land subsidence, which can damage canals, roads, and other infrastructure, and could permanently reduce the aquifer’s future storage capacity.
The NASA scientist said that persistent depletion increases the country’s vulnerability to drought, “since groundwater acts as a buffer during dry years, and that buffer shrinks as aquifers are drawn down faster than they recharge.” Eric Purnell is the founder and CEO of BlueServ Technologies and creator of Mirante, a platform that helps water and wastewater utilities identify emerging operational risks. Purnell echoed O’Neill’s concerns, telling Newsweek: “These findings are deeply concerning because groundwater supports both irrigated agriculture and drinking water supplies.” Continued depletion in the Central Valley and the southern High Plains can mean higher pumping costs, less reliable irrigation, and growing pressure on rural communities, Purnell said, adding that “farms can face serious economic consequences well before an aquifer is physically empty.” Where pumping persistently exceeds replenishment, “current use is not sustainable,” Purnell noted, pointing out that a wetter year can ease pressure, but it does not reverse decades of groundwater loss. Chaudhari told Newsweek: “I think what's concerning is how dependent agriculture can be on groundwater, especially when surface water is limited,” noting that if groundwater levels keep dropping, growers will have to face tougher decisions on “how much water they can use and what they can realistic
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