For the past 20 years, two small satellites orbiting 250 miles above Earth have tracked a stark reality about the nation’s groundwater supplies, including across the parched Colorado River Basin: The water underground is vanishing. 

The NASA satellites began gathering data in 2002. Since then, Colorado River Basin groundwater has depleted much faster than water storage in the nation’s two largest reservoirs, according to research that underscores concerns about the increasingly tight water supply in the drought-stricken West.

“We pay a tremendous amount of attention to the disappearance of surface water because we can see what’s happening with the reservoirs, Lake Powell and Mead,” hydrologist Jay Famiglietti said. Meanwhile, he warned, “groundwater is quietly disappearing.” 

Famiglietti, a professor of hydrology and executive director of the Global Institute for Water Security at the University of Saskatchewan, presented research based on the satellite data at last week’s fifth annual CSU Spur Water in the West Symposium held in Denver. Famiglietti highlighted data that showed groundwater depleting at six and a half times the rate of water storage in Lake Powell and Lake Mead between 2002 and 2014. “The results are still pretty much the same,” Famiglietti said. 

Spearheaded by NASA’s Jet Propulsion Laboratory at the California Institute of Technology, the water-tracking satellite mission is formally known as the Gravity Recovery and Climate Experiment. The GRACE satellites can effectively measure water mass from space by observing gravitational changes, Famiglietti said. 

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