REGULATORY UPDATE EPAs Multi-Sector General Permit (MSGP)

On January 15, 2021 the U.S. Environmental Protection Agency (EPA) issued the 2021 Multi-Sector General Permit (MSGP) for authorizing stormwater discharges from industrial facilities. The 2021 MSGP became effective on March 1, 2021 and supersedes the 2015 MSGP, which expired in June 2020.

Facilities with existing coverage under the 2015 MSGP must submit the new Notice of Intent (NOI) form by May 30, 2021 to continue coverage. The new NOI form is updated from its earlier version and it is prudent for facilities to implement all necessary changes and updates to the facility’s Stormwater Pollution Prevention Plan (SWPPP) per the 2021 MSGP prior to the coverage renewal deadline of May 30, 2021.

The 2021 MSGP requires facilities in 29 different industrial sectors to implement control measures and develop and make available to the public their site-specific SWPPP to comply with NPDES requirements specific for each sector. For 2021, some of the important modifications to the MSGP include:
Permittees are required to post a sign or other notice of permit coverage and SWPPP existence.
  • Additional monitoring for Polynuclear Aromatic Hydrocarbons (PAHs) at certain facilities.
  • Enhanced stormwater control measures are required for permittees in areas with higher risks to weather conditions (extreme flooding, major storms etc.).
  • Updates to frequency and reporting obligations for both indicator and benchmark monitoring.
  • Updates to benchmark monitoring thresholds and requirements for certain sectors.
  • Update to benchmark monitoring schedule. Permittees to conduct benchmark monitoring on a quarterly basis in the first and fourth years of the permit coverage. Permittees that do not exceed the four-quarter average for a parameter in the first year can discontinue monitoring for the next two years (year two and three of the permit coverage).
  • Updates to address continuous benchmark threshold exceedance. Permittees that exceed benchmark thresholds continuously (four consecutive quarters) are required to implement Additional Implementation Measures (AIM). AIMs are multi-level requirements that are triggered by continuous threshold exceedances.
  • Additional monitoring for permittees that are discharging water bodies that do not have established Total Maximum Daily Load (TMDLs). requires corrective actions in accordance with certain steps (“tiering”), first evaluating and implementing controls based on the SWPPP, then escalating to include additional control measures, and finally imposing permanent structural controls, and even treatment controls.

EPA’s 2021 MSGP applies to the following areas:
  • Massachusetts, New Hampshire, New Mexico, Puerto Rico, Idaho (until July 1, 2021), and The District of Columbia.
  • All U.S. territories except for the Virgin Islands.
  • Federally operated facilities in Colorado, Delaware, Vermont, and Washington.
  • Most Indian country lands.
  • Other designated activities in specific states (e.g., oil and gas activities in Texas and Oklahoma)
While limited to the referenced affected jurisdictions for now, the changes incorporated in the 2021 MSGP will affect all state programs eventually, when states renew their industrial stormwater permits; several states will upgrade their state-specific requirements to match the new MSGP before the end of 2021.

GSI can assist you with updating your facility’s SWPPP and also provide technical assistance to implement the changes proposed in the EPA’s 2021 MSGP. Please feel free to reach out to at This email address is being protected from spambots. You need JavaScript enabled to view it. or (713) 522 6300 if you have any questions or if you require assistance.