Stormwater Management – MS4

When it rains, do you know where the stormwater goes? Stormwater runs off of impervious surfaces such as rooftops, paved surfaces such as roads and parking lots and enters into the storm sewer system. Ultimately, stormwater drains through the system and discharges into our local streams and rivers. 

The waterways of the City of Baraboo are within the Baraboo River basin so everything that drains through the City eventually makes its way to the Baraboo River and the Wisconsin River.


What is an MS4?

MS4 is short for Municipal Separate Storm Sewer System. MS4s are conveyances or systems of conveyances including roads with drainage systems, municipal streets, catch basins, curbs, gutters, ditches, man-made channels, or storm drains that are owned or operated by a public entity, are designed or used for collecting or conveying stormwater, and are not a combined sewer or part of a publicly owned treatment works.

The City of Baraboo’s MS4 is permitted under the National Pollutant Discharge Elimination System (NPDES) program through the Wisconsin Department of Natural Resources (WDNR).  MS4 permits are granted in five-year cycles at the end of which the permit must be renewed.

City Requirements Under the MS4 Permit

The City of Baraboo must effectively and economically manage and protect its stormwater conveyance system in order to improve stormwater runoff water quality and help protect surrounding waterways.  This is accomplished through the City's Storm Water Quality Management Plan (SWQMP) and the MS4 Program's six (6) minimum control measures (MCMs):

  • Public Education and Outreach:

Educate residents and members of the business community about the impacts of stormwater on water bodies and the steps the public can take to help reduce pollutants in stormwater runoff.

  • Public Participation/Involvement:
    Provide a mechanism and process to allow the public to review and provide input on the Stormwater Management Program.
  • Illicit Detection and Elimination:
    Develop, implement and enforce a program to detect and eliminate spills, illegal dumping and other non-stormwater discharges into the City’s storm drainage system.
  • Construction Site Stormwater Runoff Control:
    Develop, implement and enforce a program to reduce pollutants in any stormwater runoff from construction areas into the City’s storm drainage system.
  • Post-construction Site Stormwater Management:
    Ensure adequate long-term operation and maintenance of stormwater Best Management Practices (BMPs) in order to prevent or minimize impacts to stormwater from new developments or redevelopments.
  • Pollution Prevention/Good Housekeeping for Municipal Operations:
    Develop and implement an operation and maintenance program with the goal of preventing or reducing pollutant runoff from municipal operations.

Stormwater Program Plan and Annual Reporting

Stormwater management is important to the City of Baraboo. Below you can review our program Plan and past reports on the progress we’ve made:

City of Baraboo’s MS4 Stormwater Program Plan (2020)

2020 MS4 Annual Report

2019 MS4 Annual Report

2018 MS4 Annual Report

Illicit Discharges

By definition, an illicit discharge is the unlawful act of disposing or dumping of any substance other than rainwater into the streets, gutters, ditches, and ponds that make up our stormwater drainage system, or directly into streams or lakes themselves.

Even some fairly common activities could be considered illicit discharge, like dumping leaves, grass clippings, motor oil, paint or other household hazard wastes into a storm drain, allowing discharges from failing septic systems, and improper disposal of sewage from boating or camping. The result is untreated garbage and filth that can contribute high levels of pollutants, like heavy metals, toxics, oil and grease, solvents, nutrients, viruses, and bacteria to our lakes and streams - so we all need to be aware of what goes into our storm drains.

If you see anyone discharging any substance other than stormwater in roadside ditches and storm drains, please report it to the City of Baraboo Engineering Department at 608-355-2730. For hazardous materials or spills, call 9-1-1 FIRST when there is an immediate threat to life or property.

Stormwater Utility:

What is a Stormwater Utility and Why was it created?
A stormwater utility creates a revenue source other than property tax dollars for the expenditures involved in maintaining stormwater runoff, including the storm sewer system and stormwater ponds.  It is funded more equitably by the users of the system than by the owner's property value.  Those that create the most runoff pay a higher fee.  Stormwater runoff is created by the amount of impervious area; rooftops, patios/decks, driveways, sidewalks and parking lots on the property.  It is anticipated that more of the revenue will be shifted from residential to non-residential property.  

How do we measure Impervious Area? 
It has been determined that the average single-family residential property in the City of Baraboo has 2379 square feet of impervious surface area.  That is the amount of area assigned to 1 ERU (Equivalent Runoff Unit).  The service fee for each single-family residential property is 1.0 ERU.  Multi-family residential property will pay 0.67 ERUs per dwelling unit.  Nonresidential property are evaluated independently to determine how many ERU's of impervious area their property has.  Information was gathered from the building inspector, assessor and engineering department, as well as aerial photography to best determine the impervious area of nonresidential property. 

How are we going to collect the fee?
Stormwater utility fees are collected on your quarterly Water & Sewer utility bill.  The charge started on your April 1, 2006 bill.  That rate was determined to be 1 ERU = $49.24 / year, which hasn’t changed since its inception.

We Can All Be Part of the Solution!

By practicing healthy household habits, homeowners can keep common pollutants like pesticides, pet waste, grass clippings, and automotive fluids off the ground and out of stormwater. More information is provided in the following links including information on how you can help!

To learn more, please visit the links below:




 Rain Garden Guide for Homeowners/Landscapers - WI DNR