The United States Environmental Protection Agency (“EPA”) published a December 13th Federal Register notice for its 2026 Clean Water Act National Pollutant Discharge Elimination System (“NPDES”) Multi-Sector General Permit for Industrial Stormwater Discharges (“MSGP”).
The MSGP is a general permit (as opposed to an induvial permit) utilized by EPA to address stormwater discharges associated with thousands of different types of facilities in the United States.
The MSGP applies to any number of businesses in multiple industrial sectors. Examples might include cement mixing, scrap metal, trucking, food processing, printing and publishing, oil and gas extraction, and asphalt paving and roofing materials. A separate general permit is used for construction activities.
EPA’s MSGP is utilized in states that do not have primacy for this Clean Water Act permitting program.
Note that Arkansas has been authorized to administer the NPDES stormwater permitting program for many years. As a result, the EPA 2026 MSGP will not be applicable in this state. Nevertheless, states with primacy often take into account to some extent EPA’s choices (i.e., in terms of permit conditions and limitations) in revising or reissuing their general stormwater permits.
EPA first established NPDES permit requirements for industrial stormwater discharges in 1990. The agency issued the first MSGP for these facilities in 1995. The 2026 MSGP represents the latest proposed renewal of this permit.
The proposed 2026 MSGP would have certain changes from the 2021 MSGP, addressing:
- Designing Stormwater Control Measures for Resiliency.
- Water Quality-Based Effluent Limitations or Other Limitations (specifying that discharges must not contain or result in observable deposits of floating solids, scum, sheen, or substances; an observable fill or sheen upon or discoloration from oil and grease; or form or substances that produce an observable change in color).
- Monitoring Changes.
- Indicator Monitoring for Per- and Polyfluoroalkyl Substances (PFAS).
- Updating monitoring requirements for certain sectors.
- Updating the benchmark monitoring schedule.
- Impaired waters monitoring (operators discharging into impaired waters must complete quarterly monitoring for all pollutants for which the water body is impaired and if a pollutant is detected the operator must do corrective action).
- Additional implementation measures.
- Updates to corrective action (conducting inspection to identify the cause of benchmark exceedance when AIM level 1 is triggered).
- Natural background exception (requirement for operators to provide analytical results of stormwater runoff from natural background and obtain EPA approval to claim a natural background exception).
- Reporting requirement to submit an AIM triggering event report to EPA in response to triggering AIM at any level.
A copy of the Federal Register notice can be downloaded here.
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