The Office of Arizona Attorney General Kris Mayes has expressed support for 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 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 letter further authorizes recipients to distribute the statement to others, including the media.
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.
The Calabasas Alliance views the Attorney General's statement as recognition that concerns raised through independent data warrant formal examination. The organization maintains that scientific findings regarding dewatering rates, the resulting cone of depression, aquifer impacts, and water quality, including reported antimony and arsenic findings, should be cross-checked against regulatory datasets, peer-reviewed university research, and transparent public data sources. Only this approach, the group says, provides communities with confidence that decisions rest on the best available science and that necessary protections for land, air, water resources, and public health will be secured.
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 review could have significant implications for the project and the region. It signals that state regulators may scrutinize mining-related water impacts more closely, potentially leading to additional data requirements or conditions on the South32 Hermosa project. For residents, the statement offers a measure of assurance that their concerns are being heard at the highest levels of state government. For the mining industry, it underscores the growing expectation that project-sponsored modeling be validated by independent analysis. The Calabasas Alliance, a grassroots organization dedicated to protecting land, air, and water resources and public health in Santa Cruz County and Southern Arizona, participates in the Arizona State University/University of Arizona AirSMART air-quality monitoring program, is a member of the Arizona Department of Environmental Quality Citizen Science Alliance, and recently received a mobile water-testing laboratory through Arizona State University's Water for All program. The group also participates in University forums on PFAS and the Arizona Rural Water Working Group.
