Title
Presentation of the Illinois Environmental Protection Agency (IEPA) General National Pollutant Discharge Elimination System (NPDES) Permit No. ILR40 for discharges from small Municipal Separate Storm Sewer Systems (MS4s).
Staff Summary
• The General Storm Water Permit for MS4s was reissued by IEPA on July 8, 2025 with an effective date of August 1, 2025.
• The previous MS4 permit expired February 28, 2021, which has been administratively continued by the IEPA over the last four years.
• There are 72 MS4s in Lake County comprised of County of Lake, Townships, and Municipalities which must submit a completed Notice of Intent to the IEPA within 90 days of the effective date, before Thursday, October 30, 2025.
• MS4 permittees must comply with any new provisions of this permit by July 31, 2026, and to include those new provisions in the 2027 Annual Report.
• Significant changes have been made in the permit based on comments received by the Agency, from the Public Notice version which IEPA released on August 27, 2021.