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Three-R Mine

Location: 

Patagonia Mountains approximately 14 miles northeast of Nogales, adjacent to Three-R Canyon, Santa Cruz County | View Map >

Date Discovered:

January 1996

Impaired Surface Waterbody:

Three-R Canyon

Surface Water Quality Exceedances for Designated Uses:

  • Copper (aquatic and wildlife, warmwater)
  • Cadmium (aquatic and wildlife, warmwater)
  • Zinc (aquatic and wildlife, warmwater)
  • Low pH (partial body contact)

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:

  • Site was intermittently mined between 1908 and 1956
  • 1996 Water quality sampling results showed excess metals present in Three-R Canyon surface water
  • ADEQ completed a water quality study, called a Total Maximum Daily Load, for Three-R Canyon in 2003. The Three-R Mine was found to be the major source degrading the water quality in the canyon
  • Owner entered into cooperative agreement with ADEQ in 2011
  • ADEQ contractor completed a Preliminary Site Assessment in 2019
  • USFS and ADEQ entered into a cooperative agreement which will allow ADEQ to complete work on the federal portion of the site in 2019
  • Remedial Investigation completed July 2020
  • Remedial Implementation began November 2020 and was completed in April 2021
  • Effectiveness Monitoring will continue through the 2021 monsoon