The U.S. Environmental Protection Agency (EPA) is proposing several key updates in the 2026 version of the Multi-Sector General Permit (MSGP) for stormwater discharges associated with industrial activities. These updates reflect the findings from recent studies, including the 2019 National Research Council (NRC) Study, and aim to further strengthen stormwater management across various industrial sectors.
Key Changes in the Proposed 2026 MSGP:
- Enhanced Stormwater Control Measures:
- Facilities are now required to regularly assess and implement stormwater controls for major storm events, based on updated flood risk data.
- Water Quality-Based Effluent Limitations:
- More precise language has been added to ensure that discharges do not result in visible contamination, including floating solids, scum, sheen, discoloration from oil and grease, foam, or a change in color.
- Monitoring updates:
- PFAS: The 2026 MSGP introduces quarterly indicator monitoring (e.g., monitor-only) for per- and polyfluoroalkyl substances (PFAS per EPA 1633), for many of the listed industrial sectors, to track these harmful chemicals in stormwater.
- Sector-Specific Shift to Benchmark: Several indicator parameters in sectors will now have benchmarks; common indicator parameters switching to benchmarks include pH, TSS, COD, ammonia, nitrate-nitrite, and certain metals.
- Benchmark Schedule: Some relief in frequency of monitoring for operators that demonstrate consistent results below the benchmark.
- Impaired Waters Monitoring: Additional monitoring of impaired waters parameters during the permit term. If you are in Pennsylvania, this provision is an extension of how DEP obtained impairment data during the most recent General Permit renewal process.
- Benchmark Exceedance Response Requirements:
- Additional reporting and inspections related to initial benchmark exceedances (Additional Implementation Measures, AIM)
Stakeholders are encouraged to review the draft and submit comments by April 5, 2025 to be considered for the final permit issuance in 2026. More details can be found here: Stormwater Discharges from Industrial Activities-EPA’s Proposed 2026 MSGP | US EPA
