On April 29, 2025, the comment period begins for the proposal to modify the Arizona Pollutant Discharge Elimination System (AZPDES) Multi-Sector General Permit for Stormwater Discharges Associated with Industrial Activities—Mineral Industry (Mining MSGP). The comment period ends May 29, 2025.

AZPDES Permit No.: AZMSG2024-002

Description of Proposed Changes: 

Following the issuance of the 2024 Mining MSGP, ADEQ identified a few typographical errors and instances of unclear language in the permit. Therefore, ADEQ intends to make the following changes through this modification:

• In Part 6.2.1 (Page 34) – ADEQ is updating the language to clarify how action levels are established for protected surface waters and non-protected surface waters where discharges may reach a protected surface water downstream.
• In footnote #2 in Part 8.G.8.2.1, Table 8.G-8.2 (Page 52) and Part 8.G.8.2.2, Table 8.G-8.3 (Page 53) – ADEQ will refer permittees to Part 6.2.1 to explain how action levels are set.
• In Table 8.G-8.3 (Page 53) – An incorrect action level for total silver was listed. The Table will be updated to reflect report-only monitoring requirements for total metals, as originally intended.

Description of the Permit Area: 

This proposed general permit authorizes stormwater discharges to protected surface waters associated with category iii, Mineral Industry sites under 40 CFR 122.26(b)(14) in Arizona, except for Indian Country as defined in 18 U.S.C. § 1151.

Review Documents: 

• Original Published Public Notice | View >
• Draft Permit | View >
• Draft Statement of Basis | View >
• In person at the ADEQ Record Center | Learn How >

Public Comment Period:

Dates: April 29, 2025 – May 29, 2025

Comments may be submitted as follows:

• By Email | Email > 
• By Mail (Must be postmarked or received by May 29, 2025):

ADEQ
Water Quality Division, Surface Water Protection

Attn:  Rachel Heinz
1110 W. Washington St.
Phoenix, AZ  85007