A paddle boat goes past a once nearly submerged island in Lake Mead near Boulder City, Nev., on Friday, Aug. 7, 2026. (AP Photo/Ty ONeil)

The largest reservoir in the United States has tumbled to a record low level as drought, extreme heat, a dearth of snow and a heavy water demand imperil the Colorado River system.

The Colorado River basin is a critical system for residents in the western U.S. and Mexico.