Groundwater Loss in Colorado River Basin Raises Concerns

• Researchers found that the Upper Basin states lost almost twice as much groundwater as the Lower Basin during a drought.
• Western states previously thought to be drought-resistant are now shown to be more vulnerable.
• Groundwater is the leading source of water loss in the Colorado River Basin as cities and farmers draw on it.
• The four Upper Basin states are Colorado, New Mexico, Utah, and Wyoming.
• The findings suggest a turning point in understanding the region's water security.