MS4 Program

What is an MS4?

MS4 stands for Municipal Separate Storm Sewer System. An MS4 entity owns or operates a system for collecting and conveying stormwater. The purpose of the MS4 program is to maintain and benefit water quality in creeks, streams and waterways by reducing pollutants in stormwater runoff.

MS4 program is an unfunded federal mandate. It is the result of the 1987 amendments to the Clean Water Act (CWA), commonly referred to as the Water Quality Act of 1987. In these amendments, Congress mandated that the U.S. Environmental Protection Agency (U.S. EPA) address non-point source pollution associated with stormwater runoff. 

In response to the Congressional action, EPA developed the MS4 program to permit the discharge of the stormwater from the MS4s. In essence, EPA defined urban stormwater (previously considered a non-point source) as a point source with numerous physical locations (or points) of discharge.

The MS4s are permitted under the National Pollutant Discharge Elimination System (NPDES) program through either the U.S. EPA or the states; in Indiana, through the Indiana Department of Environmental Management (IDEM). MS4 permits are granted in five-year cycles at the end of which the permit must be renewed. The City of Valparaiso’s NPDES permit was granted in 2003, and was renewed in 2008, 2013 and 2018.


Pollution Prevention Week

To honor Indiana's environmental achievements and recognize the collaboration between government, business, industry and citizens, Governor Eric J. Holcomb has issued a proclamation declaring September 21 - 27, 2020, Pollution Prevention Week. Indiana's proclamation coincides with National Pollution Prevention Week, which is observed the third week of September. The Pollution Prevention Week Proclamation and additional information can be found at

News on Rain Barrel Program

We have launched this year's rain barrel program. Click here for details.

Stormwater Quality Management Plan

The MS4 entities are required to develop a Stormwater Quality Management Plan (SWQMP), and to implement the following six Minimum Control Measures (MCMs) to reduce polluted stormwater runoff. Click on the links to learn about these components and what we are doing.    


The City of Valparaiso's MS4 program was recognized by Indiana Department of Environmental Management (IDEM) at the 2013, 2014, 2015 and 2018 MS4 Annual Meetings for multiple categories including illicit discharge detection and elimination, post-construction stormwater runoff control, public education/participation through rain barrel decorating competition, stormwater management utilizing trees, and programs and projects that are beyond the MS4 Stormwater Quality Management Plan.

The City's MS4 Program was also recognized by the National Municipal Stormwater and Green Infrastructure Awards Program for Innovation (Silver Level) and Program Management (Gold Level) in 2015. 

Click here to see Certificate of Recognition.
For more information about the program, please contact Mingyan Zhou, the City of Valparaiso's MS4 Coordinator.