The Office of Arizona Attorney General Kris Mayes has acknowledged community concerns about groundwater dewatering and water-quality impacts associated with the South32 Hermosa Project in Santa Cruz County, according to a statement released today by the Calabasas Alliance. The statement, transmitted in a letter dated October 26, 2026, from Chief Deputy Attorney General William Mundell, was expressly authorized for public distribution and follows the submission of background information, data, and letters from community members.
In the statement, the Attorney General's Office said, “Attorney General Kris Mayes and her office are closely monitoring community concerns regarding groundwater dewatering and water-quality impacts associated with the South32 Hermosa project in Santa Cruz County. We support a careful, independent examination of all impacts on the water resources of Southern Arizonans so that the appropriate and necessary protections can be achieved.”
The acknowledgment follows sustained, science-driven work by community members, technical professionals, and university and independent researchers who conduct ongoing water and air monitoring programs in the region. Their analyses have identified gaps in the evaluation of long-term dewatering effects, potential contaminant pathways, and cumulative impacts on local aquifers and surface waters. The Calabasas Alliance has consistently emphasized that conclusions about groundwater drawdown, aquifer connectivity, and water quality must be transparent, independently verified, and capable of withstanding rigorous technical and public scrutiny—rather than relying solely on project-sponsored modeling.
Ernie Edwards, a Lake Patagonia resident and President of the “B” Property Owners Association, said, “The pending cone of depression from dewatering is a direct threat to residents around Patagonia Lake. High-volume pumping will lower groundwater levels across a wide area, affecting wells, surface flows into the lake and the connected aquifers that supply our community and the Santa Cruz Active Management Area. We need independent hydrologic analysis now, rather than relying solely on South32 consultant models, to understand the full extent of these impacts and ensure effective protections are in place before irreversible drawdown or ground subsidence occurs.”
Robin Lucky, President of Calabasas Alliance, said, “We greatly appreciate the Attorney General's recognition that community concerns regarding groundwater dewatering, water quality and other pollution risks warrant independent examination. Residents have raised well-documented concerns regarding long-term air and water pollution risks. Massive dewatering will alter aquifer levels for decades, and questions remain regarding arsenic and other heavy metals in wells and the broader impacts in county. Transparent, science-based independent assessments are essential to safeguarding Southern Arizona's water resources and the health and well-being of our citizens.”
Lucky added that these concerns compound Santa Cruz County's longstanding pollution challenges and associated health risks, including cancer, kidney disease, and autoimmune disorders for a smaller population size. The county has recorded some of the highest PFAS levels detected in drinking water in Arizona, according to EPA and ADEQ reports, which may be associated with the treatment of raw wastewater from Mexico at the Rio Rico wastewater treatment facility. Residents also continue to face poor air quality in Nogales, as documented by the EPA and ADEQ.
The Attorney General's support for an independent examination could have significant implications for the Hermosa project and the region. It signals that state regulators may require additional scrutiny of the mine's water use and contamination risks, potentially leading to stricter conditions or delays. For residents, independent verification of dewatering impacts is seen as essential to protecting private wells, surface flows, and the connected aquifers that supply the Santa Cruz Active Management Area. The statement also underscores growing pressure on mining projects to demonstrate that their environmental assessments are transparent and scientifically robust, rather than relying solely on company-sponsored models. As the debate over water resources intensifies in Southern Arizona, the Attorney General's position may prompt other agencies to follow suit and reinforce calls for independent, peer-reviewed science in permitting decisions.
