Industrial stormwater: Permit development and program history

Stormwater runoff is a leading source of water pollution. Stormwater at industrial facilities may come into contact with harmful pollutants including toxic metals, oil, grease, de-icing salts, and other chemicals from rooftops, roads, parking lots, and from activities such as storage and material handling.

Stormwater discharges potentially containing the above pollutants are associated with 10 categories of industrial activities. These activities are regulated through NPDES permits. Facilities that need an NPDES permit must develop and implement a Stormwater Pollution Prevention Plan that is designed to eliminate or minimize stormwater contact with significant materials that may result in polluted stormwater discharges from the industrial facility. The SWPPP must also incorporate specific BMPs applicable to the facility.

2018 - 2020

Industrial stormwater program staff have officially begun the work of reissuing the 2020 general permit. 

Key dates for the reissuance process:

  • January – October 2018: Review existing permit language; sampling and other permit requirements. Draft list of suggested changes; compare EPA and Minnesota’s permit language
  • November 2018 - mid-January 2019: Draft changes
  • Mid-January – mid-February 2019: submit draft to EPA and MPCA legal staff for review.
  • March 2019: Public notice draft permit
  • April- May 2019: Review, respond to comments
  • May 31, 2019: Finalize permit language
  • June 30, 2019:  MPCA commissioner approval
  • July 5 - October 5, 2019: Permittees apply for coverage. Permittees must apply 180 days before April 5, 2020
  • April 5, 2020: “New” permit is reissued and effective

We’ve been tracking suggested changes to the 2020 permit since the 2015 permit became effective, and we will spend considerable time deliberating over these suggestions and will involve key stakeholders in the process.

A sampling of suggested changes:


  • Consider having an “I’m done sampling” form or similar requirement for sampling “closure”
  • Clarify hardness dependent adjustment language: adjust benchmarks depending on receiving waters?
  • Consider lowering all metal benchmark values to EPA’s levels for aquatic life reasons

General requirements:

  • Training requirements similar to construction stormwater's permit
  • BMP repair timelines
  • Vehicle tracking: additional requirements being considered
  • Update anti-degradation requirements to be consistent with updated rules, other stormwater programs
  • Consider increased salt management requirements


  • Clarify vehicle wash water activities where inconsistently worded in “sector chapters”
  • Construction stormwater (CSW) activities for sand & gravel facilities and landfills: consider allowing 1+ acre activities and add CSW-like language, so that a separate CSW permit is not required and requirements are consistent with the non-metallic mining general permit
  • Considering increased requirements for auto salvage yards and recycling facilities with “incidental” infiltration

If you have any suggested changes, or language you would like to see added or removed, please contact program coordinator/permit writer Melissa Wenzel:, 651-757-2816.  Emails are preferred for written documentation purposes.  

2013 - 2015

  • October 2013: MPCA staff compare USEPA's draft MSGP with Minnesota MSGP
  • November - March 2014: Draft suggested changes into draft permit
  • March 31 - April 30, 2014: 30-day public notice period for the MPCA draft permit
  • May / June 2014: MPCA staff make changes to draft permit in response to public comments
  • Late June 2014: Estimated date the draft permit is approved
  • July 7 - October 5, 2014: Time to re-apply / re-certify for permit coverage / No Exposure
  • April 5, 2015: Permit is re-issued and becomes effective

2015 documents

What changed in the 2015 permit?

Streamlined sampling requirements: All existing permittees who apply between July 7, 2014, and October 5, 2014, would conduct a year of quarterly sampling starting July 1, 2015. Any permittee who applies after April 5, 2015, will start sampling requirements during the next full calendar quarter.

Requiring four samples before averaging: Permittees will be required to collect a minimum of four samples, during four separate calendar quarters, before averages can be calculated and compared with the permit's benchmark value(s). It is acceptable if it takes more than four quarters to collect four samples; this may be because samples couldn't be collected due to drought/frozen conditions or no off-site discharges. These are considered legitimate "no flow" explanations.

Quarterly sampling until benchmark values: Permittees with exceedances will continue sampling quarterly until four quarters of averaged results are below the benchmark value.

Limitations on infiltration:  Construction of a new infiltration device is prohibited in:

  1. Areas that receive discharges from vehicle fueling and maintenance activity.
  2. Areas with less than three feet of separation distance from the bottom of the infiltration device to the elevation of the seasonally saturated soils to the top of the bedrock.
  3. Areas of predominantly Hydrologic Soil Group D (clay) soils unless allowed by a local unit of government with a current MS4 permit.
  4. Areas where soil infiltration rates are more than 8.3 inches per hour unless soils are amended to slow the infiltration rate below 8.3 inches per hour or as allowed by a local unit of government with a current MS4 permit.

2006 - 2010

The MPCA began work to reissue the expired General Stormwater Permit for Industrial Activity. Key steps along the way included:

November 2006: MPCA created the Stormwater Steering Committee’s Industrial Stormwater Work Group. It was made up of members of the Minnesota Stormwater Steering Committee and public and private organizations. The Work Group’s task was to help the Industrial Stormwater Program draft the new permit.

2010 documents

2002 - 2003


The 1997 General Stormwater Permit for Industrial Activity Permit MN G611000 expired on October 31, 2002. Before the permit expired, the MPCA drafted the Industrial Stormwater Permit and public noticed the draft for comments:

During the public notice comment period, the MPCA received written comments on several issues including requirements for outstanding resource value waters and nondegradation analysis, requirements for completed total maximum daily loads, monitoring, and SWPPPs.

In the interim, to address the time between the expired permit and reissuance of the new General Stormwater Permit for Industrial Activity, previous permit holders were covered by Minn. R. 7001.0160. “Any person who holds an expired permit…and who has submitted a timely application for reissuance of the permit may continue to conduct the permitted activity in accordance with the terms and conditions of the expired permit until the agency takes final action on the application.”

New, non-municipal facilities and newly regulated municipally owned or operated industrial facilities had to submit a permit application in order to meet the federal requirements of applying for NPDES permit coverage for industrial activity. Until the general permit was reissued, facilities had to develop and implement a SWPPP that complied with the Draft NPDES General Stormwater Permit for Industrial Activity which included the SWPPP requirements contained in the expired permit. 


EPA’s Stormwater Phase II regulations became effective on March 10, 2003, and continued to regulate the ten categories of industrial activity:

  1. Facilities subject to stormwater effluent limitation guidelines, new source performance standards, or toxic pollutant effluent standards under 40 CFR Subchapter N
  2. Heavy industrial facilities (SIC codes 24, 26, 28, 29, 311, 32,33,3441, 373
  3. Mineral industry (SIC codes 10, 12, 13, 14)
  4. Hazardous waste treatment, storage or disposal facilities
  5. Landfills, land application sites and open dumps that receive or have received industrial waste
  6. Facilities involved in recycling of material, including metal scrap yards, battery reclaimers, salvage yards, and automobile junk yards, including but limited to those classified as SIC codes 5015 and 5093
  7. Steam electric power generating facilities
  8. Transportation facilities (SIC codes 40, 41, 42 [except 4221-25], 43, 44, 45 and 5171 which have vehicle maintenance shops, equipment cleaning operations, and airport deicing operations
  9. Sewage treatment works
  10. Light industrial facilities (SIC codes 20, 21, 22, 23, 2434, 25, 265, 267, 27, 283, 285, 30, 31, 323, 34, 35, 36, 37, 38, 39, 4221, 4222 and 4225)

The regulations extended the No Exposure exclusion to all industrial stormwater categories and required municipally owned or operated industrial facilities to obtain permit coverage or certify No Exposure.