Agriculture is the dominant user of water from the overextended Colorado River, but a recent study out in the scientific journal Communications Earth & Environment shows how much water goes to agriculture compared to use by cities.

The agricultural sector is the main target for cuts in water use, as the federal government, seven southwestern states and 30 tribal nations search for ways to adapt to climate change.

Nearly three quarters of the water diverted from the Colorado River is being used for irrigation, according to the study.

“So this is not water that’s used for living in the desert, it’s for generating money,” said Andrew Curley, a professor of geography at the University of Arizona.

Farmers in the basin have over 100 years of legal and physical water infrastructure on their side, he said. “It’s been a longstanding project of both the federal government and state governments to use Colorado River for irrigation, for agriculture.”

But they’ve been allocating water based on faulty science, Curley noted. Now, overuse is catching up with the basin and drier days are coming.

Farms and ranches will have to make painful cuts to their water use, according to Sarah Porter with the Kyl Center for Water Policy.

“You’re talking about farmers not being able to grow as much, potentially really impacting rural economies,” she said.

Officials in the basin are looking for ways to leave water in the system without putting farmers out of business, Porter added.