PUBLIC MEETING | Proposed Reissuance of Multi-Sector General Permit (MSGP) for Stormwater Discharges Associated with Industrial Activities

ADEQ is proposing to reissue an Arizona Pollutant Discharge Elimination System (AZPDES) general permit, authorizing stormwater discharges associated with industrial activities to waters of the U.S.  The proposed permits are intended to replace permits AZMSG2010-002 and AZMSG2010-003. These permits are issued pursuant of the Federal Clean Water Act, in compliance with State statutes and rules. The permit covers discharges from the 29 specified industrial sectors that have stormwater discharges associated with industrial activities within Arizona, except for Indian Country.

Stakeholder Meeting

Date: Friday, April 5, 2019
Time: 9 a.m. to 12:30 p.m.
Location: ADEQ Phoenix Office, Room 3175

Join by phone: 240-454-0879; Access code: 806 376 304

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ID 806376304 Meeting password: z3rTjRJB

Meeting Agenda | View >

Review Documents & Information

Arizona SWQS v. EPA Benchmarks | View >

Based on feedback provided to ADEQ from various stakeholders, there is a concern regarding ADEQ utilizing Arizona Surface Water Quality Standards (SWQS) instead of benchmark concentrations from EPA’s industrial stormwater permit. It is important to note that the benchmark concentrations in EPA’s permit are Water Quality Criteria (WQC) established by EPA (see EPA 2015 MSGP Fact Sheet, p. 58). States have the option of implementing the EPA criteria as state SWQS or using the criteria to develop state specific standards (as is the case with Arizona). The comparison table of Arizona’s SWQS v. EPA WQC reveal that in most instances, Arizona’s SWQS are similar or higher than EPA’s WQC thereby providing greater flexibility to permittees while protecting Arizona’s surface waters and potentially triggering fewer monitoring exceedances. To this end, ADEQ is open to retaining EPA’s WQC in Arizona’s 2019 MSGP. 

Routine Analytical Monitoring | View >

To address concerns about accelerated monitoring based on a single exceedance, ADEQ is proposing to assess the need for accelerated monitoring on a case-by-case basis. ADEQ will review results and consider the concentration of pollutant(s) in the discharge, frequency of exceedances, actions taken in response to exceedances and other available information before requiring additional monitoring. If ADEQ determines additional monitoring is necessary to demonstrate compliance with permit conditions and ensure protection of public health and the environment, the department will notify the permittee in writing of the reason(s) for additional monitoring. Other components of the simplified monitoring program are retained, including:

  • Collect one sample per wet season for duration of the permit, including storm event information
  • Submit results on e-DMR within 30 days of receiving the results or 45 days from sample collection, whichever is sooner
  • Assess efficacy of existing control measures in response to an exceedance
  • Assess additional control measures if existing control measures are not adequate
  • Submit a simple Control Measure Assessment Report in myDEQ in response to an exceedance

Ephemeral Washes

ADEQ is proposing to retain analytical monitoring specified in the draft permit for total dissolved solids (TDS) and total suspended solids (TSS) for discharges to ephemeral washes. Arizona’s SWQS for sediment is Suspended Sediment Concentration (SSC) and is not applicable to ephemeral waters or to discharges to perennial waters within 48 hours after a storm event. ADEQ is proposing to utilize TSS as a means for permittees to assess the efficacy of control measures at their sites and not as a limit or action level set in the permit. Additionally, the data generated throughout the permit term would be used to better understand the variability of TSS concentrations in stormwater discharges (based on industry, storm event, etc.) and correlations to other pollutant concentrations (through sorption and mobilization) for future permitting considerations.

Past Documents Releated to January 25, 2019 Meeting

Industrial MSGP

Mining MSGP

Documents are also available for review at ADEQ's Records Center | Learn More >