The Arizona Department of Water Resources has determined that Tucson can keep its 100-year assured water supply designation. That gives the city the green light for another 10 years of expected housing development.
Rebecca Sasnett, Arizona Daily Star, File 2022
ADWR’s decision found the city had assured supplies to serve all of its customers in the immediate Tucson environs, along with customers in the Corona de Tucson area. That’s an isolated suburban area lying far southeast of the city of Tucson along Houghton Road and north of the Santa Rita Mountains.
The state designation cites the city’s annual supplies of 144,000 acre-feet of Central Arizona Project water, 37,000 acre-feet of groundwater and about 15,000 acre-feet of treated sewage effluent. It found those supplies will be “physically, continuously and legally available” for the next 100 years.
Tucson Water has demonstrated that it will have “adequate delivery, storage and treatment works” in time to satisfy an annual estimated demand of 130,794.81 acre-feet per year for at least 100 years, the state decision said.
But the possible cuts to Tucson’s CAP allotment raises questions as to how much of the supply will actually be available in the future, some outside experts have said.
The U.S. Bureau of Reclamation has said that over time, it wants to cut at least three million acre-feet of river water use. The proposals it floated in its draft environmental impact statement on the river last winter called for cuts of possibly 77% or more of Arizona’s total CAP supplies.
Arizona and other states in the lower Colorado River basin are proposing to cut a much smaller amount of CAP water over the next two years
But the state officials acknowledge the cuts could grow larger in the future.
If CAP supplies are ever cut substantially to Tucson, the new ADWR designation of an assured water supply for Tucson makes it clear that ADWR can “go back and look at this again” to see if it remains warranted, said Ferris. She’s a water lawyer who helped draft the 1980 state Groundwater Management Act that contains the assured water supply provision.