Southern Arizona property owners worried about upcoming mine's groundwater impacts

Residents living near a mega-mine slated for the Patagonia Mountains south of Tucson say they’re seeing changes to their groundwater supply as the project gets underway.

Mining company South32 says their Hermosa project will take up a roughly 750 acre stretch of land and will one day produce zinc, silver, manganese and other materials used in green energy.

South32 sent a draft agreement of a well monitoring program to area property owners in June. The document, shared with KJZZ, outlines groundwater monitoring and mitigation plans and gives the company sole discretion of how it’s done.

Robin Lucky is the president of the Calabasas Alliance — a Rio Rico community group that’s been tracking mining activity and its impact on local air quality and groundwater.

“This is the proverbial fox guarding the henhouse,” Lucky said. “That agreement they sent, it’s basically a complete takeover of part of their property.”

In an email, a South32 spokesperson said several property owners identified as being in areas with wells that could see long-term groundwater impacts from the mine were contacted.

South32 says participation in the well program is completely voluntary, and it’s an extension of an existing water monitoring program for property owners. The company says one-on-one property owner meetings will be available to answer questions and collect input.

Lucky said some property owners in the area found out their wells may be impacted by the mine’s “cone of depression’’ for the first time when they received the South32 letter.

She said her group has reached out to water monitoring officials in Arizona and at the Environmental Protection Agency asking them to look over South32’s mitigation plans.

“It's a cautionary tale — buyer beware in Arizona — especially if you're going to be in a rural area,” she said. “There's not enough being done through the legislature to deal with rural water problems.”