Arizona’s declining groundwater problem Image By EPN Staff Key Points Between 2002 and 2024, the Colorado River Basin lost 27.8 million acre-feet of groundwater, equal to Lake Mead’s full capacity, with Arizona responsible for 74% of that decline. Groundwater in the region supports nearly 40 million people, agriculture, power generation, and ecosystems. Because aquifers can take centuries to recharge, current use is unsustainable and threatens long-term food production and economic stability. The 25-year megadrought, coupled with rising demand from population growth, has accelerated water losses. Scientists warn that climate change will worsen droughts, but some farmers argue conservation practices are stabilizing groundwater locally. New research conducted by Arizona State University scientists reveals that Arizona’s groundwater supply is depleting at a rapid rate. Using NASA’s Gravity Recovery and Climate Experiment (GRACE) satellite data, scientists tracked significant losses in the Colorado River Basin’s aquifers between 2002 and 2024, with Arizona bearing the brunt of the decline. Nearly 27.8 million acre-feet, which is more than nine trillion gallons of groundwater was lost over the 22-year study period, according to the paper. “That’s an amount roughly equal to the storage capacity of Lake Mead,” said Karem Abdelmohsen, the study’s lead author in an interview with NASA. Arizona alone accounts for 74% of that loss. Why it matters Groundwater is a lifeline for Arizona. The Colorado River Basin, which covers an area of 250,000 square miles in the southwestern United States, supplies water to nearly 40 million people in seven states to support local agriculture, hydroelectric power generation, parks and recreation and habitat for fish and other wildlife. Aquifers can take hundreds, if not thousands of years, to replenish naturally. The depletion of groundwater from the river basin threatens local food production, economic stability and long-term water security as it is not being replaced at the rate that it is being consumed. These findings highlight the urgent need for sustainable water management in the region. The bigger picture The cause of the rapid decline of Arizona’s groundwater is multifaceted. The increasing population in the southwest means more people are becoming reliant on groundwater and freshwater reservoirs such as Lakes Mead and Powell. Increased drawdown outpaces freshwater replacement rate by rainfall, which is an unsustainable pattern. Additionally, the region has been in what’s called a “megadrought” for most of the last 25 years. This has exacerbated the decline of freshwater supply in the southwest, especially in Arizona according to the ASU study. The ASU scientists point to a broader global trend toward increased drought frequency and severity as a result of anthropogenic climate warming. Other peer-reviewed research suggests that increases in hydrological and agricultural drought are primarily driven by land use and poor water management, while meteorological drought has neither increased nor decreased since the 1950s. Additional details Some local farmers dispute the severity of Arizona’s water crisis, as their own conservation efforts to mitigate the effects of drought point toward stable or even increasing groundwater levels based on their own samples collected. NASA’s OpenET platform uses their satellite data to help farmers optimize irrigation, reducing water waste by aligning usage with crop needs.
