"What we expect to happen is that Lake Powell will go to unprecedented low conditions some time this fall," Schmidt added.
"Water management in the Colorado River system is starting to get terribly complicated," he added.
Projections indicate the water level will continue declining for the next eight months, which threatens hydroelectric operations and complicates negotiations over an unreliable water supply used by 40 million people across seven states, tribal nations, and two countries.
The reservoir stands just 37 feet above the critical threshold where electricity-generating turbines begin to fail, impacting nearly 6 million households and businesses that depend on the Glen Canyon power plant.
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Negotiators from California, Nevada, Arizona, New Mexico, Colorado, Utah, and Wyoming have yet to finalize a conservation agreement, leaving the US Bureau of Reclamation poised to impose forced cuts as early as next month.
"In the 21st century, the ultimate cause of the problem is declining runoff," said Schmidt. "There's less water in the system.
It's caused by a warming climate, period."
Sarah Porter, the director of the Kyl Center for Water Policy at Arizona State University, noted that southwestern cities are deploying alternate tools and voluntary frameworks to manage the shortage.
Phoenix is currently investing in recycling effluent from sewage into drinking water, while San Diego announced a plan to trade surplus water from its desalination plant to allow Arizona and Nevada to buy its unused Colorado River rights.
