During the mid-1960s, mining production in the Patagonia region came to a halt because of exhaustion of the veins, two world wars, dramatic metals market changes, and in some cases, the accumulation of water in shafts and tunnels. Since there were no regulations regarding mine closure or remediation of tailings or other disturbances, mines were simply abandoned, leaving unsafe tunnels, shafts, smelter slag, large tailings piles and disturbed ground subject to erosion.
Most of the environmental legacy of these local mines lies downstream from them. The 120 miles of Arizona streams now rated as “impaired” have over 150 endangered or threatened species of wildlife, fish and plants, including the Mexican spotted owl, jaguar and leopard frog. Sonoita Creek from Patagonia to Patagonia Lake is rated as highly impaired, and Upper Harshaw Creek as medium impaired, the same rating that Alum Gulch and Flux Canyon Creek have.
The ongoing monitoring of surface waters is part of a statewide AZDEQ program to safeguard watersheds for a multiplicity of uses by wildlife, livestock, and humans. For humans, The AZDEQ categories of water uses include “full immersion,” like swimming at Patagonia Lake State Park. Also, for humans, drinking water comes from wells in underground aquifers that are replenished in the same watersheds.
In the 50 years between 1965 and 2015, awareness grew that the historical legacy of mining was producing an array of significant pollution problems. Some ecological issues are photogenic, like the orange foamy effluent from the Lead Queen Mine (PRT, May 2018 and January 2020), while others are more subtle, like toxic dust, vegetative uptake of minerals, some of which is then eaten by creatures from cows to cockroaches, or localized damage to vegetation by acid mine drainage.
Public and governmental agency awareness has also grown about the many physical hazards of abandoned mines. The US Bureau of Land Management conducts a publicity program called “Stay Out – Stay Alive,” recognizing six types of life-threatening hazards of unprotected abandoned mines. For the five Upper Harshaw mines, there were about ten open adits and shafts, which received bat-friendly permanent gratings.
From November 16, 2020 to March 31, 2021, The Coronado National Forest Service (CNF) conducted the earthwork portion of two projects to remediate toxic tailings at six mines in the Patagonia Mountains – one on the west side, and a group of five on the east side. The motivation for this remediation work was detectable unsafe levels of mineral pollutants in the surface waters flowing from tailings. The same concern had motivated the Mansfield Canyon remediation work that PRT reported on in Nov. 2019 and Nov. 2020. For the more recent Patagonia Mountain projects, the primary strategy was also to remove and encapsulate tailings in “consolidation cells,” positioned where surface drainage would not be flowing over and through the relocated tailings.
The continuation of the work includes revegetation efforts, using straw wattles for erosion prevention on slopes, and fencing if necessary to prevent incursion from cattle. The relocated and reused soil for capping cells is considered by CNF to be a “seedbank,” so existing plants at the site which have dropped seeds will be among what grows there, aided by hydroseeding with a carefully chosen mix of seeds, avoiding “invasives.” The ideal time for this form of hydroseeding will be just before monsoon begins, as water trucks can’t serve the areas to be reseeded. The reseeded areas will be fenced against cattle wherever there are grazing allotments.
On the west side of the mountains, the remediation work focused on the Three R mine, named for Patagonia’s founder, Rollin Rice Richardson. After Richardson, the mine went through several changes of ownership, reducing and partially rearranging the 35 patented claims shown on a 1918 map to the current grouping of 20 claims as a single 371-acre parcel. The parcel was purchased by the Nash family shortly after acquiring the Circle Z Ranch in 1974 and has been put into permanent conservation easement.
The Three R parcel’s rugged land backs against the central ridge of the Patagonia Mountains, lying between about 4,800 and 6,200 feet in elevation, within the Coronado National Forest. Copper was the primary metal produced by the 3R mine, operating between 1906 and 1956, It also produced lesser qualities of silver, gold, lead, molybdenum and aluminum. It was a complex underground mine, as mine historian William Azcarza reported in a 2016 Arizona Daily Star article: “Workings of the Three R Mine include a 1,000-foot and 3,000-foot adits, three tunnels and a 558-foot shaft, along with 20,000 feet of workings.” The highest tunnels of the Three R group lie at the top of many switchbacks, so ore was originally brought down with burros. Besides very difficult access, these upper tunnels were dry and had relatively less tailings and toxicity, and thus were not in the main project, which dealt with the washes below. The surrounding CNF land is fully carpeted with unpatented claims held by Barksdale Resources, now seeking approval for its Sunnyside Exploration Project.
The water quality problems in Three R Canyon included excess levels of copper, cadmium and zinc, the three “minerals of concern” as determined by Arizona Department of Environmental Quality studies in 1996 and 2003. The downstream effects of acid mine drainage were a second concern. In a 2016 Nogales International article by Murphy Woodhouse about the accumulation of possibly hazardous materials in lake-bottom sediment at Lake Patagonia, the Three R Mine is mentioned as a significant source needing remediation. CNF environmental engineer Eli Curiel is quoted as saying “They built that right across the drainage bottom, so as the water comes down, it plows right through it and spreads it all around. This is going to be a tough project.”
The earthwork of the “tough project” is now accomplished. Approximately 9,200 cubic yards of tailings were relocated to a sloping site lower on the wash and in the CNF. Because the tailings were removed from a steep, forked canyon, extensive erosion protection was added, using precast concrete blocks at the bottoms of the washes
On the east side of the range, CNF worked on a string of five mines that are on five smaller roads going west off upper Harshaw Road, between the Hermosa Project and Guajolote Flat. Known collectively as the Upper Harshaw Project, the mines involved are Marstellar, Blue Nose, Augusta, Endless Chain, and Morning Glory. All are within a mile of Harshaw Road. These mines produced varying mixes of lead, silver, copper, zinc, and gold.
In the surface waters tested at these mines, there were excessive levels of lead and arsenic, so the minerals of concern in the Harshaw Creek watershed were different than for the Three R project. Acid mine drainage was also present below these mines. The tributary washes from each mine are at the headwaters of Patagonia’s designated municipal watershed.
Three encapsulation cells were created for tailings, the lower one at the Marstellar Mine for the first three mines, the middle cell at the Endless Chain, and the upper cell at the Morning Glory Mine. The Marstellar cell received 30,000 cubic yards of material, over three times the relocation volume at the 3R project. (To visualize that volume, imagine a football field covered 11 feet deep.) Between the first and second cells, the work was paused from March to Sept., 2021, because of Mexican Spotted Owl breeding season.
The pausing of the project also allowed some modification of the project design based on findings of tailings deeper than originally believed. This led to contract modifications that put the 5-mine total cost at $2.7 million, which was paid for out of the Tronox Settlement, a $270 million national case settled in 2011 with the buyer of Asarco’s assets after bankruptcy.
At this moment of continuing major drought, there’s no flow to be monitored near these mines, but when rain returns, and water begins flowing, future monitoring will tell if remediation projects have been successful.
In a time of continued drought, establishing new vegetation is difficult, but CNF will continue watching both water quality and revegetation for at least five years, and respond with more efforts if needed.
The remediation of mines in the Patagonia Mountains is part of a longstanding Forest Service program on Abandoned Mines and Reclamation. The program helps prioritize and accomplish projects among the 14,000 total mine sites in the U.S. which produce what the agency calls “materials that pose a high risk of chemical contamination to the environment.” The program description concludes: “To say that there’s a lot of work to be done would be putting it mildly.”