Pima County Administrator Jan Lesher has notified the five-member Board of Supervisors that Toronto-based Hudbay Minerals lacks long term Central Arizona Project water to recharge all of the groundwater the company plans to pump for its proposed Copper World mine.
Lesher told Supervisors in an April 22 memo that Hudbay has stored CAP water over the last 20 years at two different recharge basins north of Sahuarita. But the amount of CAP water is insufficient to replace all the groundwater Hudbay would pump from the groundwater basin beneath Sahuarita and Green Valley to operate the Copper World mine.
“This would be nowhere near enough to fully offset pumping for the life of the mine,” Lesher stated.
Lesher noted that Hudbay has long stated it intends to replenish all the water it uses for the mine with CAP water. Hudbay says it will accomplish this through its partnership with the Community Water Company of Green Valley to build a water pipeline to bring CAP water into Sahuarita and recharge it into groundwater replenishment basins.
The joint venture plan, called Project Renews, is not complete. Lesher stated that a Hudbay contractor informed the county that Hudbay has authorized Project Renews to be completed within two years.
Hudbay has stored enough CAP water that could be brought to Sahuarita if Project Renews is completed to operate the mine for about five years. Hudbay has stored 46,686 acre-feet of water at the Lower Santa Cruz Recharge Project in Marana and 1,683 AF at the Pima Mine Road Recharge Facility north of Sahuarita.
Hudbay is five years through a 10-year agreement to purchase 1,124 AF of CAP water a year. But the company only purchased that amount in 2022. It purchased no CAP water in 2023, and only 843 AF in 2024 and 2025. Future CAP allocations are in doubt because Colorado River flows have dramatically declined after years of drought.
Copper World records indicate the mine will pump more than 9,000 AF a year to process 60,000 tons of copper ore a day. This would equal more than 188,000 AF over 20 years. Hudbay plans to increase processing up to 90,000 tons/day for the second, 24-year phase of the mine. This would increase the total groundwater withdrawn to more than 520,00 AF.
Hudbay hasn’t announced any future CAP contracts after the current one expires in five years. Hudbay’s lack of long term CAP commitments casts doubt on its ability to meet it’s contractual agreement with the Town of Sahuarita to recharge 105% of the groundwater it pumps with CAP water.
In exchange, Sahuarita granted Hudbay the right to install a water pipeline along the Santa Rita Road that connects Hudbay’s primary well field to the mine site on the western slope of the Santa Rita Mountains.
Save the Scenic Santa Ritas submitted a petition with 133 signatures of Sahuarita residents to the Sahuarita Town Council during the May 26 meeting requesting the council hold a public hearing on Hudbay’s requirement to replenish 105% of the aquifer.
“If Hudbay cannot show it can replenish 105% of the groundwater with guaranteed contracts for CAP water, then the town should not issue permits to the company to install the water pipeline,” says SSSR Executive Director John Dougherty.
Hudbay has secured less than 10% of the CAP water it would need to replenish groundwater it would pump for the mine.
Greater Sahuarita is already experiencing ground subsidence because of groundwater overdraft. The Bureau of Reclamation in 2017 published its Green Valley Area Water Supply Study that stated the groundwater overdraft was 36,000 acre-feet in 2010.
The report stated that future use of CAP allocations including Project Renews “can compensate for some local groundwater demand but will not completely offset the overdraft.”
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