These cities are following in Phoenix’s footsteps. These agreements come after a series of successful water-sharing pilot projects between Tucson and Phoenix from 2014 to 2017.

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 ...

She says Tucson Water has about a six-year supply of water stored underground, and we do have the ability to pump groundwater as a last resort. "That's our insurance," Megdal said.