ariel view of CopperWorldAn aerial view of the roads and construction at the Copper World complex. Photo by Stu Williams

 The following fact sheet is from Save the Scenic Santa Ritas, and it is their assessment of what Hudbay plans to do with their Copperworld project. This is un-edited,

October 2023

Toronto-based Hudbay Minerals keeps changing its mining plan as it tries to paint a rosier picture for potential investors. In 2022, Hudbay released a plan for a 44-year project with an initial capital investment of $1.9 billion plan. Hudbay’s press release at the time was titled, “Hudbay Announces Robust Preliminary Economic Assessment for the Copper World Complex.” However, “robust” this $1.9 billion plan was, it was perhaps too costly to attract investors. So, in September 2023 Hudbay released a “preliminary feasibility study” that scaled back the plan to focus on a 20-year project with an initial capital investment of $1.2 billion[i]. Hudbay’s press release claimed that this new plan “De-risks Copper World Phase I,” perhaps meaning that Hudbay and investors would have to risk less money to come along for the ride. Hudbay’s stock dropped 1.4% on the day of the plans release[ii].

In the new 2023 plan, Hudbay will focus first on the west side of the mountains where in the past couple years they have already created a vast web of drill pads and access roads. Although they will start on the west side, the east “Rosemont” side isn’t safe either. In year 4 of the project, they intend to start digging what they now call the East Pit, formerly the Rosemont Mine area.

Pits:  Hudbay would excavate four pits in total. There will be 2 on the west side called “Peach/Elgin” and “West,” one on the ridgeline called “Broadtop Butte,” and one on the east slope called “East.”  The “East” pit is an expanded version of the “Rosemont” pit.  Peach/Elgin, West and Broadtop Butte would each be about 5,600 ft. in diameter (a little over a mile in diameter) and each would be about 520 ft. deep (a little over the height of a 43-story building).  The “East/Rosemont” pit would be 8,200 ft. in diameter (about 1 ½ miles in diameter) with a depth of 2,250 ft. (a little over one-half mile in depth).  These excavations would remove much of the northern ridgeline including Weigles Butte and Harts Butte.  In other words, those buttes and part of the ridgeline would vanish from the skyline.

            At some point, excavation in the East/Rosemont pit would penetrate the aquifer requiring the company to operate pumps to keep water from filling up the pit. But once mining is completed, the pumps would be turned off, and the pit would become a lake filled with toxic water creating a huge and permanent hazard to birds and other wildlife. The pit would also suck in groundwater from the surrounding region, where it would be lost to evaporation.

Water use:  Hudbay’s Copper World-Rosemont Project in the Santa Rita Mountains would consume huge amounts of water. But how much is difficult to determine as Hudbay’s publicly released mining plans continue to change. In June 2022, Hudbay presented a plan that would have consumed an annual average of 4.6 billion gallons of groundwater pumped from wells next to the Santa Cruz River for 44 years. This is enough water to supply the annual needs of 41,000 households. But earlier this month, the company sharply revised its plans and, unlike in 2022, provided no information about projected water consumption other than stating it has a permit from the State Department of Water Resources to use up to 2 billion gallons per year. Arizona water laws provide no limits on how much water mining companies can use. Hudbay is expected to eventually amend its state permit to use far more than 2 billion gallons annually.

The most significant change in Hudbay’s new mining plan is that for at least the first four years of the project it will no longer produce finished copper on site, but instead will export unrefined copper concentrate to overseas copper smelters and refineries. This will lower the amount of water and power the company will need compared to the 2022 plan during the initial four years. Beginning in the 5th year, Hudbay says it intends to build a $367 million “concentrate leaching facility” that will allow it to convert about 58% of the copper concentrate to metal. If Hudbay does build the proposed leach facility, which is far from certain, it will likely increase water consumption into the range of the previous 2022 estimate of 4 billion gallons a year.

Access: In its 2022 plan, Hudbay was going to access the mine site via SR 83. However, access has dramatically changed in the 2023 plan. Now the company proposes to access the west side pits via Sahuarita Road and then S. Santa Rita Road, which runs past Sahuarita Highlands and through the Santa Rita Experimental Range.  

Waste and tailings and state trust land:   It is not completely clear if Hudbay has sufficient private land where they can dump their waste and tailings.  Despite the federal court rulings, Hudbay is counting on eventually getting Federal permits so it can dump on the Coronado National Forest on the east side.  Of course, the recent legal opinion by the 9th Circuit Court of Appeals says they cannot do that.

The company already plans to dump a large portion of its waste and tailings on its west side private land and is seeking to buy state trust land next to the Santa Rita Experimental Range for easier access. SSSR and municipalities, tribes, and citizen groups are trying to convince the governor not to put this trust land up for auction. These parcels would bring mine construction a big step closer by giving Hudbay easier access to private land where they could dump mine tailings near homes and the Copper Ridge Elementary School.

Sulfuric Acid:  Much of the copper ore contains sulfur that must be leached out and then sold or otherwise disposed of. In their 2023 prefeasibility assessment Hudbay states that for at least for the first few years they will send copper concentrate to overseas smelters for refining, which would produce less sulfuric acid.

However, beginning in the 5th year, Hudbay plans to build a sulfur leaching facility that would produce millions of tons of concentrated sulfuric acid over the 15 remaining years of the project. To sell the acid, Hudbay will need to transport it from the mine site to the purchasers, creating a significant danger to the public. 

 Clearly, Hudbay’s proposal would be an environmental disaster that would have serious impacts on water quantity, water quality, air quality and public health, among other issues. We will continue, with your support, to do everything in our power to prevent this disaster. For more information go to

Data based on Hudbay’s Preliminary Economic Assessment, May 2022

Data based on Hudbay’s Preliminary Feasibility Study, September 2023.

                                                            Prepared by Save the Scenic Santa Ritas, October 2023.


[ii] Hudbay’s ‘enhanced’ Copper World prefeasibility gets mixed reviews – The Northern Miner


I am a retired science educator and naturalist. My research focuses on reptiles, mostly snakes. Also, I am interested in dogs and their evolution. Protecting the environment should be a high priority for everyone, particularly politicians. They seem to be in denial over the idea that the environment is our life support system - once it's damaged, it may not be fixable.

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