MS4 Stormwater General Permits

In November 2021, the Indiana Department of Environmental Management (IDEM) Office of Water Quality (OWQ) announced it would begin issuing the new Construction Stormwater General Permit and the new Municipal Separate Stormwater Systems (MS4) General Permit (GP). This comes after receiving a non-objection letter from the U.S. Environmental Protection Agency (EPA).  The effective dates of these permits and the timeline are noted below, allowing time to plan your path to compliance.

  • The start date of the permit will be December 18th.  The permit will be signed by then.
  • The permit will be public noticed for 18 days beginning on or before December 18th.
  • During this time period IDEM will make the NOI available.
  • After the NOI is made available the MS4 will have 90 days to submit the new NOI to IDEM.

Local program changes will be required to comply with the new GPs, and IDEM OWQ has issued a Draft MS4 General Permit Schedule of Compliance.

Commonwealth Engineers is currently assisting clients with the implementation of the new MS4 GP, and we have the capacity to assist you with your stormwater compliance needs. Additionally, IDEM OWQ has scheduled the following MS4 Public Information Meeting:

  • The information session for the MS4 General permit will take place on November 30, 2021, at 10:00 a.m. (EST).
  • Question Form
  • Zoom Meeting Link
  • Meeting ID: 923 4679 9028
  • Telephone: 312-626-6799
  • Passcode: 710924
  • A Construction Stormwater General Permit Public Information meeting was conducted on November 16, 2021, and the following materials are available:

If you would like to discuss how this permitting change impacts your community or utility, please contact Environmental Compliance Manager, Brady Dryer.