This permit of interest online resource provides interested parties easy access to information about the Hermosa Project, owned by South32 Hermosa Inc., formerly Arizona Minerals Inc. (AMI).

Facility Information

The Hermosa Project, owned and operated by South32 Hermosa Inc., is located approximately five miles south of the Town of Patagonia, Arizona in Santa Cruz County. 

Location

749 Harshaw Road, Patagonia, Arizona 85624

Permitting

Aquifer Protection Program Permitting Significant Amendment

On Feb. 6, 2025, ADEQ issued a significant amendment to the Aquifer Protection Program (APP) Permit for South32 Hermosa Inc.:

• APP Permit | View >
• Executive Summary | View >
• Letter to Commenters | View >
• Responsiveness Summary | View >

Clean Water Act

On July 3, 2024, ADEQ issued a renewal Clean Water Act individual permit to South32 Hermosa Inc.:

• Permit (AZ0026387) | View >
• Fact Sheet | View >
• Response to Comments | View >
• Decision to Grant Letter | View >

South32 Hermosa Inc. also has coverage under the Mining Multi-Sector General Permit (MSGP) for industrial stormwater discharges. 

• Notice of Intent (NOI) Certificate | View >
• Mining Multi-Sector General Permit (MSGP) | Learn More >

South32 Hermosa Inc. also has coverage under the De Minimis General Permit (DMGP) for water well development and maintenance. 

• Notice of Intent (NOI) Certificate | View >
• De Minimis General Permit (DMGP) | Learn More >

Public Notice

The comment period has been extended for the preliminary decision to issue the APP permit significant amendment to South32 Hermosa, Inc., for its Hermosa Project. The comment period ends on Oct. 18, 2024 | View Public Notice >

ADEQ held an in-person public hearing for the APP permit significant amendment on Oct. 2, 2024, 6 – 8 p.m.

Facility Reports

Clean Water Act

The individual permit requires regular monitoring of the treated discharge. The monitoring frequencies are specified in the permit and vary from monthly to annually, depending on the parameter. South32 must send these monitoring results to the ADEQ each month through Discharge Monitoring Reports (DMR). 

ADEQ uses these monitoring results to check if South32 is following the effluent limits set in the permit. ADEQ can change the permit if the DMR data shows there is effluent toxicity, a need for more permit limits, or if the levels in the permit are exceeded.

You can view and download the DMR data for South32 from the U.S. Environmental Protection Agency’s (EPA) Compliance and Enforcement Online (ECHO) website by entering the AZPDES Permit Number (AZ0026387) at the following link:

• South32 DMR Data | View/Download >

Facility Archives