The West Desert Trails are unmaintained trails located on approximately 1,830 acres of open space adjacent to the Sierrita Mine in Green Valley, Arizona. This property was purchased by Freeport-McMoRan Sierrita Inc. in 2012. In 2014, Sierrita completed the installation of groundwater extraction wells and related infrastructure in accordance with the sulfate mitigation effort.

Access to the property is only allowed through existing gates and trails. The land is intended to be managed for conservation purposes with the caveat that Sierrita maintains the ability to conduct mitigation operations.  For more information on the mitigation plan please visit our website https://fcx.com/sierrita

Current Update -2023 New Mitigation Wells 

Freeport-McMoRan Sierrita has successfully installed two planned mitigation wells on company-owned property in the West Desert Trails area. Well testing will start in May. 

This work is continuation of an effort that began in June 2006 when Sierrita signed a Mitigation Order on Consent (MOC) with the Arizona Department of Environmental Quality. Under the MOC, Sierrita must undertake mitigation so drinking water supplies do not exceed 250 mg/l of sulfate at the point of drinking water use due to operation of the Sierrita Tailings Impoundment. While not considered hazardous by environmental regulations, sulfate can be produces when sulfide minerals, such as those found naturally in Sierrita and elsewhere, are exposed to air and water. 


What to Expect:

•Pump testing will begin the first week of May, and you may see groundwater discharge across the desert and into nearby washes

•Testing will consist of a 10-hourstep-rate test, followed by a 24-hour constant-rate test the next day. Groundwater discharge at rated of 200 to 1,000 gallons per minute will be directed north-northeast over desert landscape to drainages that run between housing developments. 

•We anticipate most of the discharge to soak into the desert before reaching the washes, but also expect some flow into washes. Please use caution during this time, as some discharge may impact walking/biking trails in the vicinity of the well sites. 

•Full completion of the well project is expected mis-May 2023, followed by full completion of the infrastructure later in the year.

More information on the MOC can be found at Sierrita Operations Internet Document Repository | Freeport-McMoRan (fcx.com) or by visiting the Joyner-Green Valley Library. 

Questions: Please call the 24-Hour Community Information line at (520) 393-4426.