Municipally-owned and operated industrial activities

All regulated municipally-owned and -operated facilities are required to obtain either the industrial stormwater permit or certify for the No Exposure exclusion. This guidance document will assist with determining which of the two is appropriate for each facility location. Detailed information can be found in the permit at

“Municipality" means a city, village, borough, county, town, sanitary district, or other governmental subdivision or public corporation or agency created by the legislature.

“Facility” means land which has common ownership and is the location of a single corporation, business or publicly-owned operation with a portion engaged in industrial activity, even if land parcels are separated by a roadway, fence line or similar boundary.

A municipality's facility boundary is often different from a “traditional” industrial facility boundary because municipal ownership can be spread out over large distances and areas or contains several parcels of land, either connected together or may be geographically separate. For the purposes of this permit, each parcel or property’s boundaries establish a distinct facility within which primary industrial or narrative activities must be evaluated, and if relevant, apply for permit coverage or certify for No Exposure.

Who must apply?

This image shows an example of a municipality with “checker-boarded” municipally-owned and operated facility boundaries. This example could also include federal facilities or universities/colleges
Example of a municipality with “checker-boarded” municipally-owned and operated facility boundaries. This example could also include federal facilities or universities/colleges

Each facility, whether privately or municipally owned, must identify all of its industrial activities and compare them with Primary Standard Industrial Classification (SIC) codes found within the permit under Appendix D: Sectors of Industrial Activities Authorized (see last page for web link). Each facility evaluation is facility/address-specific and each facility location within the municipality must be evaluated to determine if it needs permit coverage. If any of the facility’s activities fall within a “Primary” or “Narrative” SIC code, an application for permit coverage or No Exposure certification is required.

The Primary SIC code represents the activity that produces the facility’s largest revenue. If revenue data is not available or relevant, then select the SIC code activity with the largest number of employees. If using employee data is not possible or applicable, use the SIC code representing the largest volume of production.

A comprehensive list of SIC code descriptions can be found at: [ here].

What is the No Exposure exclusion? Can I certify for that?

The No Exposure exclusion allows industrial facilities, including municipal facilities, with materials and activities that are entirely sheltered from stormwater 100% of the time, to certify they have a condition of “No Exposure.” Facilities who can certify for No Exposure do not have to develop a Stormwater Pollution Prevention Plan (SWPPP), conduct inspections, fill out the annual report, pay the annual fee or conduct monitoring. Visit for more information about the No Exposure exclusion.

Municipally-owned and -operated activities that require permit coverage or No Exposure certification

Landfills: All landfills that accept industrial wastes (process waste received from any of the facilities within the 29 Sectors of industrial activity, including demolition landfills, municipal solid waste landfills and open and closed landfills).

Recycling centers/transfer stations: All recycling centers and transfer stations that accept waste for sorting and distribution, including Material Recovery Facilities that receive paper, glass, plastic and aluminum from non-industrial sources.

Activities include but are not limited to:

  • Processing, reclaiming and wholesale distribution of scrap and waste materials, such as ferrous and nonferrous metals, paper, plastic, cardboard, glass and animal hides.
  • Reclaiming and recycling of liquid wastes, such as used oil, antifreeze, mineral spirits and industrial solvents.

Wastewater treatment facilities: Any wastewater treatment facility treating wastewater that includes domestic sewage with a design flow of 1.0 million gallons per day or more. Also included is land dedicated to the disposal of sewage sludge that is located within the confines of this facility. Any wastewater treatment facility that treats wastewater that includes domestic sewage with a design flow of 1.0 million gallons per day or more is required to have an approved pre-treatment program under 40 CFR part 403 (Disposal of Sewage Sludge, Delegated Pretreatment Program).

Steam electric generating facilities: Steam electric power generating facilities, no matter what the fuel source, are required to apply for permit coverage or certify for No Exposure.

Airports: If the Primary SIC code is:

  • 4512 Air transportation, scheduled
  • 4513 Air courier services
  • 4522 Air transportation, nonscheduled
  • 4581 Airports, flying fields, and airport terminal services

Ambulance: For ambulance service facilities classified under SIC code 4119 (Local Passenger Transportation Not Elsewhere Classified) where vehicle maintenance is conducted at the facility.

Vanpool: Vanpool operation facilities classified under SIC code 4119 (Local Passenger Transportation Not Elsewhere Classified) where vehicle maintenance is conducted at the facility.

Garbage trucks: Garbage trucks and trucks used for local collecting and transporting (without disposal) may be classified under Primary SIC code 4212 (Local Trucking without Storage). To be characterized as SIC code 4212, the facility must be primarily engaged in maintaining the trucks. If a municipality also owns the disposal facility, such as a landfill, that receives refuse transported by the trucks, the maintenance facility would be classified as a landfill and considered “co-located”.

Note: only air, water and land transportation facilities that are conducting vehicle maintenance activities are required to be regulated. Vehicle maintenance includes vehicle rehabilitation, mechanical repairs, painting, fueling, lubrication and equipment cleaning operations.

Construction sand and gravel, aggregate hot mix asphalt and concrete activities: Facilities with 100% of their industrial activities covered under the “General Permit for Construction Sand and Gravel, Aggregate and Hot Mix Asphalt Facilities Permit” (MNG49) do not need to apply for permit coverage. Any facility not covered under that permit should apply for either that permit or the industrial stormwater multi-sector general permit.

The MNG49 Permit can cover multiple locations. If a facility has additional industrial activities beyond what are listed above, either obtain the multi-sector general permit for the location that has additional industrial activities (such as local trucking or landfill activities) or obtain the multi-sector general permit for portions of the facility with these additional activities.

Solid waste facility: Many solid waste activities are regulated by the industrial stormwater multi-sector general permit. Solid waste activities listed within the permit’s Appendix D must obtain industrial stormwater permit coverage as well as solid waste permit coverage. While many solid waste permits have stormwater requirements, solid waste permits do not have legal authority to regulate water quality NPDES requirements.

Co-located activities

If a municipally-owned and -operated facility is regulated for a Narrative Activity or Primary SIC code, all additional applicable activities within the facility boundary are also regulated. For example, if a municipality owns and operates a landfill across the street from its recycling center, the facility boundary would be drawn around both properties and considered one facility; both activities are regulated under one permit and one application is required.

Municipal activities that do not require permit coverage (with noted exceptions)

  • libraries
  • liquor stores
  • city halls
  • community centers
  • schools
  • arenas
  • water towers
  • golf courses
  • swimming pools
  • potable water treatment plants

Individual permit: If a municipally-owned and -operated facility has an individual wastewater discharge permit or other water permit (general or individual) with stormwater requirements, the facility does not need to apply for permit coverage.

School bus operations: The SIC Manual states that “school bus establishments operated by educational institutions should be treated as auxiliaries” to the educational establishment. Because the SIC code assigned to educational institutions is 82xx, municipally-operated school bus establishments would not be required to apply for a permit for their stormwater discharges. Private contract school bus services are required to apply for an NPDES permit for their stormwater discharges.

Police cars, fire trucks and snow plows: Police, fire protection and city road snow plowing activities are classified under SIC code 92xx (public order and safety). Therefore, even a maintenance facility primarily engaged in servicing those vehicles, would not need permit coverage.

Municipal buildings: Other municipal buildings which are not connected to a regulated industrial facility (i.e., city or county offices) are not regulated.

Salt piles: Salt piles alone do not require stormwater permit coverage. However, if a regulated facility has a salt pile, their salt storage must be addressed with stormwater control measures and within the facility SWPPP. Additionally, all salt piles must be prevented from creating saline runoff to surrounding land or surface water.

Public works buildings: Most public works buildings are not regulated because no industrial activities are conducted at the location, or are considered secondary activities to the Primary SIC code of 9199, General Government, Not Elsewhere Classified. For example, a publicly-owned government facility has an administrative office and maintains the city’s police cars, fire trucks and snow plows. This location’s greatest revenue, generation, or personnel are dedicated to administrative activities and the Primary SIC code of 9199. The co-located activities of SIC 9221, 9224 and 9229 are also not regulated, therefore no permit is required. Other co-located activities at this facility (for example, vehicle maintenance for trucks used in local trucking, or a Sector N recycling center or warehouse) would also not require a permit. However, if a narrative activity is also being conducted at the same property, permit coverage would be required.

Maintenance garages: Maintenance garages that are primarily engaged in maintaining vehicles related to road maintenance and construction (i.e., winter plowing, dump trucks, heavy equipment graders, front-end loaders, or tractors) are classified under SIC code 16xx (heavy construction other than building construction) and would not need permit coverage. Most public works or maintenance garages would likely be classified as SIC code 16xx regardless of whether or not maintenance of those vehicles is conducted at the facility. Maintenance of vehicles (e.g. cars/pickup trucks) used by city staff (i.e. city administrator, etc.) are considered a secondary activity and are not regulated.

Other maintenance shops: Small engine maintenance shops that primarily engage in repairing small engines, such as lawn maintenance equipment and snow blowers, etc., do not need permit coverage.

Wastewater treatment facilities:Wastewater treatment facilities designed to treat less than one million gallons per day or those that collect and treat the stormwater as part of the normal inflow that is processed through the treatment plant, are not required to apply for a permit. Stormwater mixed with wastewater becomes wastewater and is addressed by the facility’s NPDES permit.

Compost facilities include municipal, commercial, industrial, or yard waste facilities. Many composting facilities currently do not require permit coverage.

Exception: Compost manufacturing companies (industrial composting facilities) are often categories under the Primary SIC code 2875 – “Fertilizers, mixing only,” and requires coverage for establishments primarily engaged in manufacturing materials:

  • compost
  • fertilizers, mixed: made in plants not manufacturing fertilizer
  • potting soil, mixed

My municipality is required to get a Municipal Separate Storm Sewer (MS4) permit for discharges municipality-wide. How does the permitting for my industrial facilities fit in with the MS4 permit?

The MS4 permit requires stormwater controls for areas such as streets, city storm drains, roads, highways and municipal parking lots. Industrial facility activities are regulated under the industrial stormwater permit and not regulated by the MS4 permit. If a municipality’s facility has industrial stormwater permit coverage, then those areas do not need to be included under the MS4 permit’s Good Housekeeping Program.

I’m regulated by the industrial stormwater permit. What do I need to do next?

  • develop a SWPPP and choose stormwater control measures
  • apply for permit coverage
  • conduct monthly inspections
  • fill out an annual report
  • pay the annual fee
  • conduct monitoring

Additional information and guidance

Visit the industrial stormwater program’s website [ here} to:

  • Download a copy of the permit and application materials.
  • Access Sector-specific fact sheets.
  • Download a copy of industrial stormwater monitoring requirements and best management practices.
  • Subscribe to the industrial stormwater program updates Email list.
  • View state and federal rules related to industrial stormwater permit.

To hear recorded industrial stormwater technical information, call the Stormwater Hotline at 651-757-2119 or 800-657-3804 (non-Metro only). Program staff is available during regular weekday business hours at 800-657-3864. Page

This page was last edited on 5 December 2022, at 17:21.