Arizona AG Backs Independent Review of South32 Hermosa Water Impacts

The Arizona Attorney General’s Office has acknowledged community concerns about groundwater dewatering and water-quality impacts linked to the South32 Hermosa Project in Santa Cruz County, following a push from the Calabasas Alliance. In a statement released by the grassroots group, Attorney General Kris Mayes and her office said they are “closely monitoring” the issues and support a “careful, independent examination” of all impacts on Southern Arizona’s water resources. The statement, transmitted in a letter dated October 26, 2026, from Chief Deputy Attorney General William Mundell, was expressly authorized for public distribution, marking a formal recognition of the concerns raised by residents and independent researchers.

The Calabasas Alliance, a community-based organization focused on protecting land, air, water, and public health, has stressed that conclusions about groundwater drawdown, aquifer connectivity, and water quality—including reported antimony and arsenic findings—must be transparent, independently verified, and cross-checked against regulatory datasets and peer-reviewed research. Ernie Edwards, president of the “B” Property Owners Association, warned that the pending cone of depression from dewatering threatens wells, surface flows into Patagonia Lake, and connected aquifers, calling for independent hydrologic analysis rather than reliance solely on South32 consultant models. Robin Lucky, president of the Calabasas Alliance, added that massive dewatering will alter aquifer levels for decades and that transparent, science-based assessments are essential to safeguarding Southern Arizona’s water and public health.

The Alliance also highlighted broader pollution challenges in Santa Cruz County, including some of the highest PFAS levels detected in Arizona drinking water—possibly linked to treatment of raw wastewater from Mexico at the Rio Rico facility—and poor air quality in Nogales documented by the EPA and ADEQ. The organization is a principal community partner for the ASU/UA AirSMART air-quality monitoring program, 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 Attorney General’s acknowledgment is seen as a validation of sustained, science-driven efforts by community members, technical professionals, and university researchers who conduct ongoing water and air monitoring in the region.