Colorado River Basin Lost 27.8 Million Acre-Feet Of Groundwater—Lake Mead At 34% And Falling

Since 2003, the Colorado River Basin has lost 27.8 million acre-feet of groundwater — enough to fill Lake Mead entirely. Total water loss across the basin reached 42.3 million acre-feet. Groundwater makes up the majority of that figure. It’s also disappearing twice as fast as surface water from reservoirs.

The rate of loss has gotten much worse. Since 2015, depletion’s been happening three times faster than in the previous decade. Groundwater’s declining 2.4 times faster than surface water. It’s draining faster than Lake Powell and Lake Mead are losing water combined. Scientists say climate change is driving this acceleration.

Since 2015, groundwater depletion has accelerated three times faster — outpacing even the combined losses of Lake Powell and Lake Mead.

NASA satellites are tracking these changes. The satellites monitor both below-ground and above-ground water supplies. They’ve mapped water loss across all seven Colorado River Basin states since 2003. This technology allows scientists to measure groundwater across the entire basin for the first time.

The Lower Basin — Arizona, California, and Nevada — is hit hardest. Groundwater supplies 40% of the Lower Basin‘s total water. It accounts for 71% of the region’s total water losses. In the Upper Basin — Wyoming, Colorado, New Mexico, and Utah — groundwater makes up 53% of total depletions.

Several factors are driving these losses. Demand’s outpacing what the Colorado River can supply. Farmers and industries are turning to groundwater to fill the gap. Agriculture uses the most water in the region. Industrial-scale farming and overpumping are major contributors. Rising temperatures and the growth of data centers are reportedly adding more pressure.

Agriculture faces the biggest consequences. The economy and food production in the region are at serious risk. The Lower Basin’s economy is especially vulnerable since it’s already in a water-scarce area.

Groundwater’s largely been left out of Colorado River water agreements. Overpumping often goes unregulated. Surface water levels are easy to see — groundwater loss isn’t. Arizona’s Active Management Areas have helped slow depletion in some areas. Arizona’s Groundwater Management Act of 1980 established a legislative framework that has been credited with saving roughly 25 cubic kilometers of groundwater over three decades. Experts warn the region is not on track to adequately protect its remaining water supplies. But experts say much more needs to be done to protect what’s left underground. The basin supplies water to 40 million people across seven states, all of whom depend on a system that is increasingly strained.

✅ Claims in this article were verified using AI-assisted fact-checking.