LOS ANGELES (AP) — Earlier this year, several environmental groups sent a petition to the federal government with a message: Ensure that water from the Colorado River is not wasted and only being delivered for “reasonable” and “beneficial” uses.

The organizations urged the Bureau of Reclamation to use its authority to curb water waste in the Lower Basin states: California, Arizona and Nevada. They argued it was necessary to help address the river’s water shortages.

The concept of reasonable and beneficial use is not new, but it’s being discussed at a crucial moment. Chronic overuse, drought and rising temperatures have shrunk water flows.

States reliant on the river are approaching a 2026 deadline to decide on new rules for sharing its supplies, and they have until mid-November to reach a preliminary agreement or risk federal intervention.

The petitioning groups argue reducing water waste could help ensure the river has a sustainable future, but others worry cuts could bring hardship to farmers and consumers.

The river supports 40 million people across seven states, two states in Mexico and Native American tribes.

“We don’t have a management future for the Colorado River right now and it’s getting pretty scary,” said Mark Gold, adjunct professor at the University of California, Los Angeles, and former director of water scarcity solutions with the Natural Resources Defense Council, a petition group. “We should be dealing with this as a water scarcity emergency, and one of the things that you really want to do in an emergency is, let’s deal with water waste first.”

The bureau has not responded to the petition. In a statement to The Associated Press, the agency said it continues to operate with the agreements and rules in place and has other strategies to “reduce the risk of reaching critical elevations” at the river’s reservoirs, Lakes Powell and Mead.

A bureau code says “deliveries of Colorado River water to each Contractor will not exceed those reasonably required for beneficial use.”

Cara Horowitz, director of UCLA’s Frank G. Wells Environmental Law Clinic, wasn’t sure what that meant or how it’s applied. So she and her students sought to find out with government records.

“As best as we could tell, it’s never defined the phrase and it does not use the phrase in any meaningful way as it’s making water delivery decisions,” said Horowitz, who is representing the groups. They believe the bureau needs a reformed process to determine whether states are avoiding wasteful and unreasonable use. In the petition, the groups urged the bureau to address those issues and perform periodic reviews of water use.

Researchers say that defining reasonable and beneficial use could be challenging, but some argue it’s worth a try. Others worry that allowing an authority to determine what’s wasteful could have negative impacts.

“It’s potentially a whole can of worms that we need to approach very carefully,” said Sarah Porter, the Kyl Center for Water Policy director at Arizona State University. “Who gets to be the entity that decides what’s an appropriate amount of use for any particular water user or community?”

The groups see it differently. For example, they think farmers should be incentivized to change “wasteful” irrigation practices and consider growing crops better suited for certain climates.

An example they gave of “unreasonable” use is year-round flood irrigation of thirsty crops in deserts. In cities and industries, wasteful use includes watering ornamental turf or using water-intensive cooling systems.