MS4 and IDDE

What is an MS4?

A Municipal Separate Storm Sewer System (MS4), is a storm water collection and conveyance system that transfers untreated storm water directly to waters of the United States. This system is not combined with other systems, such as a sanitary system which would need to be treated through a wastewater treatment plant before it is discharged. To prevent pollutants from being transferred through these systems, National Pollutant Discharge Elimination System (NPDES) Permits and Storm Water Management Plans (SWMPs) are utilized to ensure the discharge of pollutants from these systems are minimized. Each year, municipalities must reapply through an MS4 Permit to ensure that they are maintaining compliance with their NPDES Permits and SWMPs.

To see the annual report for this year, click here.

Illicit Discharge Detection & Elimination Program

The Illicit Discharge Detection & Elimination (IDDE) Program is an annual program that investigates MS4 outfalls throughout the City of Oshkosh to determine if there are any illicit discharges. These inspections are conducted with both a visual screening during wet season conditions (spring and summer) and chemical analysis through dry season conditions (fall and winter). The purpose of this program is to find and eliminate any illicit discharges within the MS4 system.

To see findings from previous years IDDE Reports, please click here.