MN Stormwater News Fall 2020

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November 2020

New MS4 permit to be issued soon

The new MPCA Municipal Separate Storm Sewer System (MS4) General NPDES Permit will be reissued Monday November 16, 2020. Existing MS4 permittees will have 150 days (until April 15, 2021) to complete and submit their permit application forms to the MPCA. For more information about the upcoming permit application process, please visit the MPCA municipal stormwater website.

New MS4 permit chloride reduction requirements

Salt pic

The revised MS4 permit includes new requirements aimed at reducing chloride pollution. They include:

  • Community outreach and education about the environmental harm posed by de-icing salt use
  • Implementing a written snow and ice management policy
  • Training for those performing winter maintenance activities for the permittee
  • Proper de-icing salt storage practices

Some permittees must also conduct an annual winter maintenance operations assessment to assist in identifying de-icing salt reduction opportunities on permittee owned/operated surfaces. The MPCA Stormwater Wiki offers guidance on requirements for permittees that have an applicable wasteload allocation (WLA) for chloride and meeting chloride TMDL permit requirements.

A recent online virtual discussion was hosted by the MPCA for permittees to discuss the new chloride permit requirements, hear success stories from other MS4s that have already realized the benefits of smarter salting practices, and to answer any questions about the new requirements.The recorded WebEx event and the presentations can be found on the MPCA Water permit holders and chloride webpage.This site also offers a more detailed summary of all chloride related requirements.

The MPCA Smart Salting Certification Training Program is available to permittees as an option to meet the training requirement.The MPCA Smart Salting Assessment tool (SSAt) is an optional tool available to assist with conducting annual assessments. It’s a free online tool that can be used to evaluate your winter maintenance operations and help your organization identify and plan for future salt reduction activities.

Check out the new Statewide Chloride Management Plan on public notice now for additional support in reducing chloride.The plan was developed in cooperation with stakeholders from around the state.The plan may be used to:

  • Better understand chloride sources.
  • Determine goals for local reductions in salt use.
  • Detect and prioritize critical areas for reducing salt use.
  • Implement and measure those goals.
  • Research strategies to reach local goals.
  • Implement and measure those goals.
  • Learn what tools and resources the MPCA has for reducing salt use

For more information about the MS4 General Permit reissuance, visit the MPCA municipal stormwater webpage. If you have additional questions about the new chloride-related permit requirements, please contact


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