As the Colorado Rivers water supply faces a murky future, cities near Phoenix are staying prepared for shortages by making deals with the city of Tucson.

Earlier this month, the city of Tucson entered agreements to store and exchange water with the cities of Scottsdale, Peoria and Gilbert.

We are one of the largest groundwater-based systems in the country, Tucson Water director John Kmiec told KGUN 9. And we can store excess water beyond what the city of Tucson needs. So were making our storage facilities available for these other communities to store with us.

Under the agreements, the Phoenix-area cities will bank some of their excess water from the Central Arizona Project in Tucsons aquifers, located west of the city in Avra Valley. One of the main facilities is the Southern Avra Valley Storage & Recovery Project.

During a future water shortage or potential cuts, those cities would then be able to take water from Tucsons CAP allotment.

Tucson and Phoenix have held water sharing agreements like this since 2017.

We can store excess water, said Kmiec. These other communities dont have that option. They take water directly from the canal on a daily basis, in most cases, and directly deliver it to their customers that way.

Thats why the cities are using Tucsons aquifers as a sort of water ATM.

They are paying Tucson roughly $75 per acre-foot of water stored.

The agreements state that Scottsdale can store up to 3,000 acre-feet of CAP water per year for 10 years; Gilbert, 300 acre-feet; and Peoria, 10,000 acre-feet.

One acre-foot of water supplies roughly three homes for a year.

Now, many more homes will have a backup water bank just outside the Old Pueblo.

It makes Tucson very resilient and flexible, said Kmiec. And now those other communities in the Valley, by using the Tucson facilities, can make them more flexible.

Tucson Water says Scottsdale has officially signed off on its agreement, while Peoria and Gilbert are still working to approve their agreements.