The Office of Arizona Attorney General Kris Mayes has thrown its support behind an independent examination of groundwater dewatering and water-quality impacts associated with the South32 Hermosa mining 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 acknowledges community concerns about the project’s hydrological effects.
“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,” the statement reads. “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 Attorney General’s acknowledgment follows sustained, science-driven work by community members, technical professionals, and university and independent researchers who conduct ongoing water and air monitoring 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 argued 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.
The intervention matters because it elevates a local dispute over a major mining project to the state level, signaling that Arizona’s top legal officer considers the concerns credible enough to warrant formal examination. The Hermosa project, proposed by Australian mining giant South32, would involve significant dewatering to access mineral deposits, a process that critics say could lower groundwater levels across a wide area and affect wells, surface flows, and interconnected aquifers.
Ernie Edwards, a Lake Patagonia resident and president of the “B” Property Owners Association, warned that 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,” Edwards said. “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 the Calabasas Alliance, said the group greatly appreciates the Attorney General’s recognition that community concerns regarding groundwater dewatering, water quality, and other pollution risks warrant independent examination. “Massive dewatering will alter aquifer levels for decades, and questions remain regarding arsenic and other heavy metals in wells and the broader impacts in the county,” Lucky said. “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, including some of the highest PFAS levels detected in Arizona drinking water, according to EPA and ADEQ reports, and poor air quality in Nogales. The Attorney General’s support for an independent review could increase pressure on regulators to require additional data and may influence the project’s permitting trajectory, though no specific regulatory action was announced.
