The Colorado River Compact is a 100-year-old document that apportions water rights throughout the entire Colorado River Basin. This is a massive area that includes land in seven states and a population of roughly 40 million people.
The compact, signed in 1922, estimates that 15 million acre-feet of water, about the current volume of Great Salt Lake, flow through the river. Half of that, or 7.5 million acre-feet, goes to Arizona, Nevada, and California, the lower basin states. The other half goes to Utah, Colorado, Wyoming, and New Mexico, the upper basin states.
But there’s a problem with this model. Fifteen million acre-feet is an overestimation. It’s more like 13 million acre-feet that actually flow through the river each year. But the law mandates that the lower basin states get their 7.5 million acre-feet, even when flows are abnormally low.
That’s the case right now. For the past 20 years, the southwest has been engulfed in a megadrought that has reduced river and reservoir levels.
“In a lot of ways, it's worst-case scenario," said Mike Drake, the deputy state engineer from the Utah Division of Water Rights. "Though we have other alternatives out there, if we need to, we can implement curtailment.”
The curtailment that Drake refers to means that Utah might have to cut water to its own towns and farmers to supply the water it is legally obliged to release into Arizona, Nevada, and California.
Drake said that while water is curtailed from individual water users every day in Utah depending on precipitation and climate patterns, the basin-wide curtailment is a new problem that we’ve never encountered before.
“The idea of curtailment is not new," Drake says. "It's a thing we do, but the unprecedented nature is the scale. No one's ever had to regulate water on a basin wide perspective. Certainly in the western United States, we haven't seen something like this. We don't know exactly how this is going to happen.”
We don’t know yet how much Utah would have to cut water use, or if it will at all. It’s possible that Utah could challenge the lower basin states in court. But the old water right laws are enshrined in Utah Constitution.
Representatives from the Colorado River Basin states are working towards a renegotiation of water sharing guidelines adopted as temporary modifications of the Colorado River Compact in recent years.
If no agreement is reached by Nov. 11, 2025, the federal government may intervene and implement an alternative plan created without the input of states.
