MS4 General Permit Now on Public Notice

On November 25, 2020, the Indiana Department of Environmental Management (IDEM) issued a Public Notice for the Municipal Separate Storm Sewer System (MS4) General Permit.  Once this permit becomes effective in 2021, Indiana MS4 entities will need to begin implementing changes to demonstrate compliance with the new General Permit.

Interested parties can submit comments or inquiries about the general permit to  The comment period ends on January 25, 2021.

We would also like to take this opportunity to remind you that the 2019-2020 MS4 Annual Reports under the current permit coverage are due on April 1, 2021.

Commonwealth Engineers has been actively monitoring the evolution of the MS4 General Permit from the current permit by rule approach and has participated in IDEM’s MS4 General Permit Work Group.  If you would like to discuss how this permitting change impacts your community or utility, please contact Brady Dryer.