“They like to say, ‘Oh, the management’s doing well,’” Jay Famiglietti said, but looking out over the next century, the trends suggest the aquifers will continue to empty out. “No one talks about that. I don’t think it’s an exaggeration to say it’s an existential issue for cities like Phoenix.”

“These findings send perhaps the most alarming message yet about the impact of climate change on our water resources,” said Jay Famiglietti, the study’s principal investigator and a Global Futures Professor with the ASU School of Sustainability. 

“We use a lot of water to grow food,” said Jay Famiglietti, a professor at Arizona State University’s School of Sustainability and one of the authors of the study. “If things don’t change, we’ll see impacts on our food security and just our general water availability.”

Still, the lack of agreement between states on future guidelines has also created a lot of uncertainty for water users, said Kathryn Sorensen, the director of research at the Kyl Center for Water Policy at Arizona State University.

“There’s a total unknown still about what happens after the current shortage sharing guidelines expire, and what will be the new operating guidelines. There’s a lot of uncertainty, and uncertainty is difficult to plan around,” Sorensen said.

“This is an early warning. There is something that needs to be fixed,” said Karem Abdelmohsen, an ASU researcher and co-author of a study on groundwater changes over the last 20 years. “Groundwater storage is our savings account,” Abdelmohsen said. “Surface water is our spending account. And in our situation, we are using both accounts at the same time.”

Sarah Porter, director of the Kyl Center for Water Policy at Arizona State University, also expressed concern. She doubts it's a good long term solution, especially with shortages of Colorado River water and the chances that the drought-caused shortages mean the amount the state can withdraw will shrink.

"If left unmanaged for another decade, groundwater levels will continue to drop, putting Arizona’s water security and food production at far greater risk than is being acknowledged,” said Jay Famiglietti of ASU, previously a senior water scientist at NASA’s Jet Propulsion Laboratory.

Sarah Porter is the director of the Kyl Center for Water Policy at Arizona State University. She says this inter-basin transfer isn't a total answer to ensuring that Arizona has enough water to continue to grow.

"Increasingly, I think there's a recognition that we need to find some other water supplies."

ASU researchers are working with Arizona water managers to develop a tool to encourage more sustainable landscaping.

Professor Daoquin Tong is with ASU’s School of Geographical Sciences and Urban Planning. She says they hope to create large-scale water savings for the Central Arizona Project region by identifying areas of nonfunctional turfgrass and offering sustainable landscaping alternatives.