Learn how to determine if your facility requires MSGP coverage, file a Notice of Intent, and implement a compliant Stormwater Pollution Prevention Plan.
If your facility's primary industrial activity matches an SIC code in the EPA Multi-Sector General Permit (MSGP) and you discharge stormwater to U.S. waters, you must obtain coverage. You file a Notice of Intent and implement a Stormwater Pollution Prevention Plan. The 2021 MSGP expired on February 28, 2026, but remains in force for existing permittees under administrative continuation.
Which facilities must obtain MSGP coverage?
Facilities whose primary industrial activity matches an SIC code in Appendix D, Table D-1, must obtain coverage if they discharge stormwater associated with that activity. Permit eligibility is limited to discharges from facilities in the specific sectors of industrial activity summarized in that table. These sector descriptions are based on Standard Industrial Classification Codes and Industrial Activity Codes.
EPA’s 2021 MSGP applies in areas where EPA is the NPDES permitting authority. These areas include Massachusetts, New Hampshire, New Mexico, and Idaho, as well as the District of Columbia, Puerto Rico, all U.S. territories except for the Virgin Islands, federally operated facilities in Colorado, Delaware, Vermont, and Washington, most Indian country lands, and other designated activities in specific states. Federally operated facilities in Colorado, Delaware, Vermont, and Washington also fall under this permit. If your facility is in a state with its own authorized NPDES program, you follow that state’s specific industrial stormwater rules instead.
How do you determine your sector?
Identify the SIC code for your primary industrial activity and cross-reference it with Table D-1 in Appendix D. If the code is listed, you fall under that sector’s specific requirements. References to sectors in the permit refer to these groupings, which dictate your monitoring and control obligations.
For example, Sector A covers Timber Products, including General Sawmills and Planing Mills under SIC 2421. Sector C covers Chemicals, such as Agricultural Chemicals under SIC 2873-2879. If your primary industrial activity has been assigned a SIC Code listed in Appendix D and you discharge stormwater, you are required to obtain permit coverage. This applies even if the activity does not clearly fit within that SIC code description. If there is any uncertainty about whether your facility falls within a particular SIC code, contact EPA for assistance in making the determination of applicability.
What is the current status of the 2021 MSGP?
The 2021 MSGP expired on February 28, 2026, at 11:59 p.m. eastern time. EPA did not reissue a new permit prior to its expiration. Therefore, the 2021 MSGP has been administratively continued in accordance with section 558(c) of the Administrative Procedure Act. It remains in force and effect for facilities and operators that were covered under the permit prior to its expiration.
New facilities cannot obtain coverage until EPA reissues the permit. Existing permittees must continue to comply with all current requirements, including monitoring and reporting. The administrative continuation ensures that regulatory obligations remain active for those already holding coverage. You should monitor EPA announcements for the reissued permit, as new terms may apply once it is finalized.
How do you get and keep coverage?
File a Notice of Intent to obtain coverage under the permit. Implement a Stormwater Pollution Prevention Plan before discharges begin. Maintain compliance with all monitoring, inspection, and reporting requirements throughout the permit term. To terminate coverage, file a Notice of Termination after ceasing discharges associated with industrial activity.
The NOI must be submitted to the appropriate permitting authority before you begin discharging stormwater. Your SWPPP must be developed and implemented in accordance with good engineering practices. It should identify the responsible person for on-site implementation. You must also ensure that all employees involved in stormwater management receive adequate training. Recordkeeping is essential to demonstrate ongoing compliance with the permit’s terms and conditions.
What must a SWPPP contain?
A SWPPP must identify sources of pollution, describe control measures, assign responsibilities, and document areas exposed to precipitation. It must be tailored to the actual activities at your facility. The plan should reflect the specific industrial processes and materials handled on-site.
For Timber Products facilities, you must document in your SWPPP where processing areas, treatment chemical storage areas, and treated wood storage areas may be exposed to precipitation or stormwater. If your facility has used chlorophenolic, creosote, or chromium-copper-arsenic formulations for wood surface protection, you must document areas where contaminated soils and stored materials remain. You should also describe the management practices employed to minimize contact of these materials with stormwater.
Which control measures are required?
Control measures include good housekeeping, secondary containment, and specific practices for co-located activities. Sector-specific requirements in Part 8 dictate additional controls based on your industrial activity. You must comply with these requirements associated with your primary industrial activity and any co-located activities.
In areas where storage, loading, unloading, and material handling occur, perform good housekeeping to minimize the discharge of debris and dust. This assessment evaluates the usefulness of practices to minimize the deposit of treatment chemicals on unprotected soils. Stormwater discharges from areas with contact with chemical formulations sprayed for surface protection are not covered by the permit and require a separate NPDES permit.
What monitoring does the permit require?
Monitoring frequency and pollutants depend on your sector. Most sectors require periodic sampling for specific parameters such as pH, total suspended solids, and metals. Additional sector-specific pollutants may be required based on the industrial activity. You must collect samples from each drainage area on your site according to the permit’s schedule.
The 2021 MSGP requires discharge monitoring and annual reports to EPA. Sampling events are typically tied to stormwater effluent events, ensuring that data reflects actual discharge conditions. Lab results must be submitted within the timeframe specified by the permit. If your sector has specific monitoring requirements, they are detailed in Part 8 of the permit. Always verify the exact parameters and frequency for your sector to avoid non-compliance.
What happens if benchmark monitoring results exceed the threshold?
Exceeding a benchmark triggers a requirement for corrective action. The facility must investigate the source of the exceedance, implement additional controls, and document the response in the SWPPP. This process ensures that pollutant levels are brought back within acceptable limits.
When sample results exceed a Numeric Action Level, the permit requires a response action. You must identify the cause of the exceedance and take steps to prevent recurrence. This may include improving housekeeping, adding containment structures, or installing treatment systems. Document all actions taken and the results of any follow-up monitoring. If you are facing repeated exceedances, consider seeking expert guidance to close the gap between your current controls and permit requirements. See hiring a water treatment specialist to close a permit gap for steps to address persistent issues.
What inspections and recordkeeping are required?
Facilities must conduct routine visual inspections of the site, document findings, and maintain records of monitoring data. You must also keep records of SWPPP updates and employee training. Annual reports must be submitted to EPA or the relevant state authority.
Inspections should cover all areas where industrial activity occurs and where stormwater may be generated. Document any deficiencies found and the corrective actions taken. Retain all records for the duration required by the permit, typically several years after the reporting period. These records serve as evidence of your compliance efforts and are subject to review by regulators.
Where does treatment fit in the compliance plan?
When housekeeping and sediment controls are insufficient to meet benchmarks, treatment media can target dissolved pollutants like metals or hydrocarbons. Sediment controls often miss the dissolved fraction of pollutants that remain in the water column. Treatment media can be integrated into existing infrastructure to address these specific contaminants.
For facilities with high dissolved pollutant loads, adding a treatment step may be necessary to achieve compliance. This can include using filtration media designed for specific contaminants, such as heavy metals or hydrocarbons. The choice of treatment depends on the pollutant profile and site conditions. If you are dealing with bacteria or nutrient loading, see bacteria TMDL stormwater compliance for MS4 permit holders for guidance on addressing those specific challenges.
Next Steps
If you need help matching treatment solutions to your permit requirements, contact us for a site assessment.