MS4 Information & Resources

Stormwater regulations associated with the Federal Clean Water Act (CWA) are administered under the Municipal Separate Storm Sewer System (MS4) Program.  In Pennsylvania, the MS4 program is managed by the Pennsylvania Department of Protection (PADEP).  Operators of a small MS4 must obtain an NPDES permit and develop and implement a stormwater management plan (SWMP) according to the details of their specific permit.  Mandatory elements of the SWMP include six (6) Minimum Control Measures (MCMs); each MCM has a number of associated BMPs.  Explore the links below to learn more about the requirements, resources for meeting those requirements, and more.

MS4 Information & Resources Menu

NEW! Important Deadlines section

DEP has some useful links for municipal separate storm sewer system (MS4) resources on its website, including guidance for mapping, calculations, modeling and Minimum Control Measure (MCM) implementation.  Check out the web-based GIS application that provides a visual map of the information in the MS4 requirements table, including the impaired streams by municipality and county, and designated urban areas. If you have any questions, don’t hesitate to contact the Bureau of Clean Water (BCW) at, or by phone at 717-787-5017. 

New Interactive Map Makes Municipal Separate Storm Sewer System Permit Process Easier for Local Governments
Visit DEP’s press release here:
The Pennsylvania Department of Environmental Protection (DEP) has developed a new geospatial information system (GIS) mapping website to help local governments and other entities pursuing permits for municipal separate storm sewer systems (MS4s) to obtain information for their permit applications more easily. The new MS4 requirements GIS website gives municipalities with regulated small MS4s an interactive, georeferenced map that visually integrates urbanized areas, waterways flowing through and near those areas, and pollutant reduction responsibilities that municipalities may need to address for waterways that are impaired and receive stormwater discharges from their MS4s. The new MS4 GIS website is a great supplement to the MS4 Requirements Table of the specific requirements for the MS4 application.

  1. MS4 Workshop Materials
  2. Public Education and Outreach (MCM #1)
  3. Public Involvement and Participation (MCM #2)
  4. Illicit Discharge Detection and Elimination (MCM #3)
  5. Construction Site Stormwater Runoff Control (MCM #4)
  6. Post-Construction Stormwater Management (PCSM) in New and Re-Development Activities (MCM #5)
  7. Pollution Prevention / Good Housekeeping for Municipal Operations (MCM #6)



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UPDATED! Quick Resource Guide to the MS4 Program

Quick Resource Guide for Winter Maintenance BMPs

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General MS4 Information Public Education & Outreach Public Involvement & Participation Illicit Discharge Detection & Elimination Construction Site Stowmwater Runoff Control Post-Construction Stormwater Mgt in New & Redevelopment Activities Pollution Prevention/Good Housekeeping for Municipal Operations