More Colorado River water is used to grow a single crop than for drinking water, business needs and industrial uses combined across the seven-state river basin that’s home to more than 40 million people, a new analysis has found.

Water used to grow alfalfa — which is used to feed cattle — makes up more than a quarter of all human usage of the Colorado River, according to the analysis published last week in the academic journal Communications Earth & Environment.

The analysts’ work is the most comprehensive accounting of where precious Colorado River water goes as it flows downstream and thins to a trickle before reaching the Gulf of California in Mexico. The estimates account for water exported outside the basin to cities like Denver, Santa Fe and Los Angeles, as well as water use in Mexico and on the Gila River, one of the largest tributaries to the Colorado. The analysis also accounts for water lost to evaporation from reservoirs and in the natural environment.

“We thought it was really important to provide this fuller, more comprehensive perspective on where the river goes and to bring nature into the conversation,” said Brian Richter, the lead author of the analysis and president of Sustainable Waters, a global organization focused on water scarcity challenges.

Knowing how we are using water is important for shaping effective policy on how to manage the shrinking river in the future, Richter said.

The analysis comes as the seven Colorado River states, the 30 tribal nations on the river and the U.S. Bureau of Reclamation craft new long-term rules that will dictate how shortages are managed when there is not enough water — which is most years.

“We felt some urgency to get this study done because of the negotiations going on, and we wanted to get the most accurate numbers in front of them,” said Richter, who has published several other analyses of Colorado River use.

Here’s what Richter and his team learned when examining how the river was used between 2000 and 2019.

How much are we using?

Nearly every year, people use more Colorado River water than snow and rain can replenish.

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