The climate change-fueled megadrought parching the American West hit another critical milestone on Tuesday: Lake Powell reached its lowest point since the government dammed the Colorado River at Glen Canyon more than half a century ago. Even more ominously, the worst drought since Charlamagne has pushed water levels to just 35 feet above the point at which the hydroelectric dam can no longer produce electricity, which it supplies to 54 Native American tribes and another 5 million customers across the region. If water is withheld to keep levels higher, that could have dramatic consequences for the even larger Lake Mead, which is only 14 feet above a critical water shortage leve.

The ongoing drought and falling water levels have boosted calls to decommission and “rewild” the Colorado River. Snowmelt from the Rockies is expected to alleviate Lake Powell’s immediate shortage, but hydrology models suggest a 25% chance the lake will be too low to generate electricity as early as 2024. “The continued long-term trend of decline in the reservoir is disturbing,” Tom Buschatzke, director of Arizona Department of Water Resources, told the Arizona Republic. (The Colorado Sun, AP, Fox13; Decommissioning: Arizona Republic; Climate Signals background: Drought)