The mighty Colorado River, which supplies water to cities and farms across Southern California, could again dwindle to dangerously low levels next year.
That’s the finding of a new analysis published earlier this month by a group of prominent scholars. They claim the river is closer than previously thought to running into serious infrastructure complications that could stop water from flowing.
Around two-thirds of San Diego County’s water — and all of Imperial County’s water — comes from the imperiled river. Four tribal nations in California and the cities of Tijuana and Mexicali also rely on it heavily as a water source.
Jack Schmidt, director of the Center for Colorado River Studies and lead author of the new analysis, said the group is asking the Trump administration to force all seven states that rely on the Colorado River to slash their water use.
“An immediate crisis has crept up on us,” Schmidt said.
The Colorado River has been slowly drying up since the turn of the century.
The ancient river basin faces rising temperatures and drier conditions, both fueled by human-caused climate change. The river itself is also governed by a 100-year-old agreement based on outdated estimates, which grants the states more water than actually exists in the river today.
At stake is the water source for 40 million people and 5.5 million acres of farmland.
The warning comes three years after an intense drought threatened the Colorado River. The dry weather raised fears that the river could stop flowing entirely, until a series of rain and snowstorms arrived and relieved some of those pressures.
Much of the attention around the river is now focused on the seven states that are scrambling to meet a major approaching deadline on how to protect the river’s health. Those states have until October 2026 to come up with a new plan for sharing the river — or risk those negotiations collapsing.
But according to Schmidt and his co-authors, the Colorado River is already nearing a precarious point.
The group of researchers, which includes a former top official at the United States Department of the Interior and water officials from three other states, reached this finding by analyzing federal data.
The worst-case scenario for the river is “dead pool.” That would happen if water levels in one of the river’s two major reservoirs, Lake Powell and Lake Mead, fell low enough that the river actually stopped flowing.
Theoretically, dead pool would happen if water levels fell below 3,370 feet for Lake Powell or 895 feet for Lake Mead.
However, Schmidt said federal officials actually think the infrastructure of a reservoir like Lake Powell would start to buckle much sooner — at around 3,500 feet.
The current water level in Lake Powell is around 3545 feet.
If the water level falls below that threshold, Schmidt said, water managers could risk sucking air bubbles into the turbines inside Glen Canyon Dam. Those bubbles could create shockwaves that would destroy the turbines.
That means water officials could be forced to shut down the dam as a precaution, cutting off the main outlet for water to leave Lake Powell and keep flowing downstream.
If that happens, Lake Powell also has a set of secondary release points called “river outlets,” where water officials could keep water flowing temporarily. But those tubes are old and only meant to be used sparingly, Schmidt said.
“Then you are in uncharted territory,” he said.
If cuts do happen, both San Diego and Imperial County would probably be last in line to face them.
That’s because the Imperial Irrigation District (IID), Imperial County’s influential water agency, claims some of the oldest legal rights to draw water from the river. Those claims are tied to the valley’s history of farming and Gold Rush-era settlements.
San Diego County receives a major cut of that water through a decades-old agreement called the Quantification Settlement Agreement, or QSA.
According to Jim Madaffer, who represents San Diego County’s water agency on the state Colorado River Board, that means San Diegans should be guaranteed stability — despite the warnings about the river’s health.
“We have probably the most reliable water supply anywhere in the West,” Madaffer said.
In Imperial County, water officials and farmers have made strides in reducing their overall water use, Schmidt and IID officials said. IID has agreed to major cuts to protect the river’s health in recent years.
This year, Imperial County’s water use fell to its lowest point in 20 years, IID spokesperson Robert Schettler said in a statement.
But that also means less water flowing into the Salton Sea, which researchers fear is polluting the air in both the Imperial and Coachella Valleys as it dries up.
