Arizona has 51 groundwater basins.

Yet new studies estimate that agriculture in just five of them used nearly 420,000 acre-feet of water in 2022.

That’s roughly the amount of water that Phoenix and Tucson — the state’s two largest cities — deliver to taps in a year.

I point that out not to shame farmers for their use, or to suggest that one use is better than the other (it’s not).

I point it out because everyone needs to understand the scale of water depletion in these basins, so we can have a more informed debate about what could help stabilize them.

A state law passed last year requires the Arizona Department of Water Resources to complete basic supply and demand studies for each basin every five years.

It chose to study in the first round the adjacent Willcox and Douglas basins in southeast Arizona, where stories of dry wells and land fissures have captured international headlines for years.

It also took on the three transportation basins west of Phoenix that were set aside in the 1990s for major cities to one day tap: Butler Valley, McMullen Valley and Harquahala Valley.

Agriculture is the primary water use in each of these basins, and in most cases, the department found........

© Arizona Republic