Facilities in specific industries that store materials, waste, or equipment outdoors are subject to industrial stormwater regulations administered by the MPCA in a multi-sector general stormwater permit. The current permit is set to expire March 31, 2025.

The MPCA issued a draft of the new permit on January 27, 2025. The MPCA is still reviewing comments on the proposed draft permit, and if the permit is not issued by March 31, 2025the current permit will remain effective until the new permit is issued. Facilities are required to certify no exposure or apply for coverage via e-Services once the new permit is issued. Significant new changes were proposed in the draft permit. The most notable are regarding new requirements for Per-and Polyfluoroalkyl Substances (PFAS) including monitoring for sites that previously qualified for the no exposure exclusion. 

PFAs related changes 

• The MPCA is now requiring monitoring for certain PFAS for facilities in 46 specific SIC codes (listed in Appendix D of the draft permit) for at least four separate runoff events. 
• Facilities applying for a No Exposure exclusion are also required to have sampled stormwater for PFAS four times. 
• Permitted facilities with an SIC code listed in Appendix D are also required to develop and implement a PFAS stormwater monitoring plan. 

Monitoring related changes 

• Added language and requirements around where to collect a sample, when to collect a sample, how to collect a sample, and what to do if unable to collect a sample.
• The permit includes more specifics around which parameter must be sampled for each industrial sector and subsector. 
• Added language if any single benchmark monitoring sample is 4 times over the benchmark value, it is considered an exceedance of the benchmark value. If this occurs, the permittee needs to complete the steps required after a benchmark value exceedance described in 50.3. 

SWPPP related changes 

The MPCA added additional requirements related to the facilities Stormwater Pollution Prevention Plan (SWPPP) including: 

• Discussing how the facility will minimize runoff from the use of salt or other de-icing/anti-icing materials used on the property.
• Detailing a maintenance plan for stormwater sedimentation and infiltration basins to be included in in the plan.
• Outlining specific instances that would require a facility to modify the SWPPP within 30 days of the change.   
• Specifying the SWPPP must document all stormwater BMPs that are implemented to comply with Part X of the permit when an impaired or special water is identified within one mile of an industrial facility’s benchmark monitoring location and where the identified impaired or special water receives discharge from the industrial facility’s stormwater monitoring location. 

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