On Monday, Nov. 16, the Coronado National Forest Service (CNF) began a five-mine remediation project in the upper Harshaw Creek area, between Guajalote Flat and the Hermosa Project. The project intends to reduce pollution from multiple minerals, primarily arsenic and lead, present at elevated levels at all five mines. Other contaminants of concern include selenium, cadmium, copper, and zinc. All five mines are within Patagonia’s designated Municipal Watershed. The public comment period (in May) for the project had included questions and requests from the Hopi Nation, South32, and Patagonia Area Resource Alliance.
To understand the presence and movements of these contaminants from mining, the project area has been extensively studied, beginning with flow studies by the Arizona Department of Environmental Quality in 2003, and a 2015 US Geological Survey study, in partnership with the CNF. This partnership studied in detail 94 samples of rock, tailings, sediment and surface flow. The CNF’s “Removal Action Approval Memorandum” of October 30, 2020 cited the USGS conclusion “that mine waste erosion and the accumulation of evaporative salts from acidic, metal-enriched discharge from abandoned mine sites are the largest contributor to degraded streamflow during storm events.” The Memorandum particularly notes detrimental effects of lead exposure, and observes that, while there are no residences at these mine sites, there are many types of users of the area, such as hunters and hikers, and that a string of ranches and residents are downstream on the Creek’s path to its junction with Sonoita Creek at Patagonia. The studies also mentioned other pathways of movement of contaminants in ecosystems, such as uptake by plants and animals.
The historic mines involved are the Marstellar, August, Blue Nose, Morning Glory and Endless Chain. The plans are unique for each mine, using the same strategies as PRT had reported on for the recent Mansfield Canyon remediation project in the Santa Rita Mountains, including tailings relocation, capping and revegetating of “cells” in which tailings are placed, surface revegetation with fenced enclosures and erosion control, and closure of tunnels and shafts by either filling or bat-friendly grates. In addition, a small bit of new access road will be needed for one of the mines, and the completion of the work on three of the mines will involve elimination of three already decommissioned Forest Service roads which are short spurs on the west side of Harshaw Road. For all earth movements of this project, the intention is to leave surfaces looking as natural as possible.
The project’s total tailings relocation will be about 44,600 cubic yards of mine waste, about half of which is from the Endless Chain Mine. These mines were operated from the 1880s to 1950s, producing varying amounts of copper, zinc, lead, silver and gold. South32 maintains unpatented claims in the entire area of this project. There are no current proposals to explore or mine where this remediation project is occurring. The work on the first three mines is planned for completion by March 2021. There will be periodic disruptions of traffic on upper Harshaw Road, so residents and other users might consider Apache Road or Duquesne Road as alternates. The second phase of the project is planned for completion in October 2021, with total project cost estimated at $1.53 million.
CNF sees this project as expressive of their mission. Hailey Stock, a CNF environmental engineer, was quoted by Tucson news station KOLD as saying, “Maintaining public lands within the Coronado National Forest is important for community and environmental health. We value the protection and safety of communities in and surrounding the Forest, and the clean-up of abandoned mines is one way we can continue our commitment to public safety and forest restoration.”