Curated News
By: NewsRamp Editorial Staff
December 07, 2025
South32 Hermosa Mine Discharge Hits Record Antimony Levels, Threatening Arizona Water
TLDR
- South32 Hermosa Mine's discharge shows the highest antimony concentration recorded, exceeding Arizona's Alert Level and approaching regulatory limits, raising concerns about compliance and environmental risks.
- The October 31, 2025 sample measured 5.73 µg/L of antimony, above the 4.8 µg/L Alert Level and near the 6 µg/L discharge limit, triggering a required 30-day study.
- This contamination threatens Patagonia's sole groundwater source, risking community health and wildlife, highlighting the need for transparency and protection of shared water resources.
- Antimony exposure from mining discharge can cause severe health issues like stomach cancer and organ damage, while also harming local ecosystems and wildlife.
Impact - Why it Matters
This news matters because it reveals a critical environmental and public health threat in a region already vulnerable to water scarcity and contamination. Antimony exposure through drinking water can cause severe health issues, including cancer and organ damage, while the mine's planned expansion to pump millions of gallons daily risks long-term contamination of Patagonia's sole groundwater source. The deficiencies in water treatment and regulatory delays highlight systemic failures in protecting communities from industrial pollution, emphasizing the need for transparency, timely data, and stronger oversight to safeguard water resources essential for health, agriculture, and ecosystems in drought-prone areas.
Summary
A recent water quality sample from the South32 Hermosa Mine discharge near Patagonia, Arizona, has revealed alarming levels of antimony, recording the highest concentration to date at 5.73 micrograms per liter (µg/L). This measurement exceeds Arizona's Aquifer Protection Permit (APP) Alert Level of 4.8 µg/L and approaches the state's regulatory discharge limit of 6 µg/L, triggering mandatory 30-day studies under APP rules. The data, reported through the Arizona Pollutant Discharge Elimination System (AZPDES), shows an upward trend in antimony concentrations as discharge flows increase, raising significant concerns among community members about potential current exceedances given the 30–60 day reporting delay to the public.
The issue highlights deficiencies in the mine's unique water treatment plant, which appears unable to adequately reduce antimony concentrations even at relatively low flow rates of 1-2 million gallons per day. Volunteer scientists have compiled monitoring data showing that higher discharge flows correlate with increased metal concentrations, with arsenic levels decreasing after treatment adjustments while antimony remains problematic. Community advocates, including hydrologist Chris Gardner and Robin Lucky, President of the Calabasas Alliance, emphasize that environmental monitoring by the public is crucial for transparency and accountability, as the mine plans to pump millions of gallons of groundwater daily for operations, with much of it discharged after treatment.
Beyond immediate water quality concerns, the discharge poses severe risks to the Patagonia region's groundwater, which serves as the sole water source for the town and relies significantly on the Harshaw Creek watershed. Antimony, a toxic mining byproduct, can cause gastrointestinal issues, respiratory problems, organ damage, and even cancer with chronic exposure through drinking water, also impacting wildlife and ecosystems. The Calabasas Alliance and local residents are calling for timely information, honest data accounting, and greater regulatory oversight to protect human health, the environment, and water resources in Santa Cruz County, where drought and existing mineralization from abandoned mines compound the threats.
Source Statement
This curated news summary relied on content disributed by Newsworthy.ai. Read the original source here, South32 Hermosa Mine Discharge Hits Record Antimony Levels, Threatening Arizona Water
