Stormwater Management

​WisDOT manages more than 11,000 miles of state and interstate highway, including numerous drainage systems to help clear stormwater from the driving surface. These systems help keep roadways safe and passable. They also create health benefits for surface and ground waters.

Stormwater Management

Clean water is vital to public health. WisDOT has worked for decades with key stakeholders such as the Wisconsin Department of Natural Resources (WDNR) to ensure appropriate controls and policies. This is because rain, snow and ice eventually turn into surface waters that flow from hard surfaces, such as driveways and streets, into drains and ditches that ultimately lead to natural water systems. Stormwater runoff can carry contaminants such as fertilizer, oil and grease or pet waste. That’s why WisDOT has tapped the environmental expertise of the WDNR for many years to develop solutions that help to clean and filter highway storm runoff. Stormwater

Elements of the WisDOT Stormwater Management Program include:

  • Transportation Separate Storm Sewer System (TS4) permit
  • Adopt-a-highway cleanups
  • Working to reduce dependence on road salt
  • Street-sweeping leaves and debris from urban freeways
  • Annual tracking through the TS4 Annual Report to WDNR
  • Project-specific stormwater management planning
  • GIS mapping to streamline planning and maintenance
  • Continued education for engineers and staff

You can help

Cleaner runoff makes for cleaner natural water systems. Here are some tips to consider.

  • Promptly fix any vehicle that is leaking oil or other fluids.
  • Wash car on grass or gravel when possible to keep water from storm drains.
  • Dispose of automotive and household chemicals properly – never down a storm drain.
  • Pick up litter, debris and pet waste for proper disposal.
  • Use a disposal service or contact your local wastewater plant to handle travel trailer waste.
  • If you witness a hazardous spill or illicit discharge, report it to the WDNR at 1-800-943-0003.

Transportation Separate Storm Sewer System Permit (TS4)

Highway and bridge projects throughout Wisconsin's state highway system must adhere to the guidelines in the TRANS 401code and WisDOT's Facilities Development Manual. In 2018, WisDOT and the DNR launched the Transportation Separate Storm Sewer System (TS4) permit to formalize DNR's role in oversight and more easily ensure ​compliance with state and federal law. The TS4 permit is modeled on a similar permit that Wisconsin municipalities have used since the 1990s. The TS4 is a permit comprehensive to all state highways within urban areas, which helps to create consistency and quality control statewide. The TS4 is necessary for Clean Water Act compliance and helps to ensure clean water for fish, wildlife, commerce and recreation.


​Civil engineers and environmental staff use various types of maps (topographic, soils, aerial, property divisions, road locations, floodplains, environmental features, etc.) for stormwater management planning, system​wide​ stormwater analysis and roadway design. These maps can be obtained from County, Municipal, WDNR, NRCS, FEMA and other agencies websites. In addition, WisDOT has created it’s own Map Viewer specific to its stormwater requirements:

Stormwater &Environmental Map Viewer. Currently, this map focuses on stormwater management concerns in urbanized areas. Check back as it is expected that additional environmental functionality will be added over time. Please note that this GIS based mapping system is only available to WisDOT staff at this time.

Legal Requirements

  • FDM 10-1-2 Applicable Laws and Regulations
  • TRANS 401 Construction site erosion control and stormwater management

FDM References


See the forms and tools page for factor sheets and guidance

Stormwater drainage summary report

Stormwater drainage water quality report

References and tools

FHWA information/guidebooks