Lake Powell, which sits on the Arizona-Utah border, is the nation's second-largest reservoir. On Tuesday its water levels dropped to an all-time low, falling past a record set last April.
If levels keep dropping, they could get too low to generate power in Glen Canyon Dam, or even pass through the dam at all.
“I think decision makers are trying so hard to prop up Lake Powell because they’re really afraid of the infrastructure problems at the dam when it operates below power pool,” said Eric Balken, executive director of the conservation group Glen Canyon Institute.
Arizona and other states that rely on the Colorado River have come up with a patchwork of measures to prop up Lake Powell in recent years.
But they’ve been unable to agree on long-term plans to cut water use.