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Exposed Reef Mine


Patagonia Mountains, approximately 20 miles northeast of Nogales, accessed via Flux Canyon Road, Santa Cruz County

Date Discovered:

April 1, 2019

Impaired Surface Waterbody:

Alum Gulch

Surface Water Quality Exceedances for Designated Uses:

  • Dissolved copper (aquatic and wildlife, ephemeral)
  • Dissolved zinc (aquatic and wildlife, ephemeral)
  • Total copper (partial body contact, agricultural livestock watering)
  • Total zinc (partial body contact, agricultural livestock watering)

Affected Media:

  • Surface Water

What Are My Health Risks?

For Surface Water | Surface water quality standards are established to provide protection for a waterbody’s designated use(s) | Learn more >

ADEQ and AZGFD jointly publish fish consumption advisories | Learn more >

For Soil | There is little to no health risk unless there is contact with skin or ingestion of contaminated soil

For Groundwater | If you are connected to a Public Water System (PWS) there is little to no risk of impact from exceedances because the water is filtered through the PWS for residential and business use | View Drinking Water Notices >

If you have a private well in the vicinity of the exceedance, we encourage you to test the well water. Not sure what to test for? | Learn More >

For Mining Adits/Shafts | If you encounter a mining adit or shaft, do not enter it. The Arizona State Mine Inspector conducts inspections of legacy mines and implements safety measures | Learn more >

Site Summary:

  • ADEQ conducted site inspection and water quality sampling in April 2019
  • April 2019 samples showed exceedances in surface water quality standards
  • Communication with landowner established in October 2019
  • ADEQ installed stream monitoring and camera instruments in July 2020 at the confluence of Alum Gulch and Exposed Reef Mine
  • ADEQ gathering stream flow data to determine extent of Exposed Reef Mine adit discharge into Alum Gulch