Watershed Study Flood Risk Map
The City of Madison started a Watershed Study Program in January 2019 as a result of the floods in June and August 2018. The Watershed Study Program details the existing flood risk in the City. Then, that information is used to create a long-term plan of solutions to lessen the flood risk. The solutions will be constructed as funding becomes available.
Flooding occurs when there is too much stormwater and it doesn’t have anywhere to go. Most of the flooding in the City of Madison is considered flash flooding. To learn about why we experience flash flooding in Madison, please view the Flash Flooding story map.
To learn more about other types of flooding, please visit the Understanding Flooding webpage.
Areas Without Detailed Watershed Study Information
The flood risk map shows detailed flood depths for a storm that has a 1% chance of occurring in areas where watershed studies have competed this analysis.
In some areas, studies have just begun, or will not begin for a few more years, and there is not detailed flood risk mapping available. In these areas, the map shows less accurate and less detailed information: where the existing soils suggest areas historically flooded—that is a placeholder until the studies are complete. We can tell where areas historically flooded by looking for indicators in soils beneath our homes and roads that classify them as hydric. Hydric soils suggest areas flooded in the past and are on the map in magenta inside watersheds without detailed flood mapping.
The yellow lines on the isthmus represent streets that are at elevated risk for flash flooding during intense rain events when lake levels are high. Please note, the yellow and magenta general flood information is not specific to any certain rain event.
In areas where there currently is not detailed flood risk information, residents can use privately generated tools, such as Flood Factor, to better understand their flood risk.
If your home is at risk in the 1% chance event:
When you click on the map, if you’re looking at an area with detailed mapping, you will see if there could be flooding around your home during a storm that has a 1% chance of occurring annually—6.66 inches of rain in 24 hours. If your home shows flooding, this does not mean your home will flood. It means your home has a higher risk of flooding.
We encourage you to take a look at our flooding resources webpage to help you prepare for potential flooding.
You can also visit the watershed study project to learn what flood solution projects are proposed in your watershed to help reduce flooding.
Differences from FEMA Flood Map
This is not a FEMA Flood Map.
FEMA Flood Maps (flood hazard analysis) focus on flooding from rivers overflowing or from coastal flooding, not urban flash flooding. The City does have some FEMA flood hazard areas in the City such as Starkweather Creek or the Madison Lakes. But, that mapping is found on FEMA’s website; not here.
This map exists to help you quickly get information about general flood risks. This map doesn't identify all areas that may flood or predict future flooding.
Do not use this map to make official flood risk determinations for insurance, lending, or other purposes. This is not an official FEMA federal Flood Insurance Rate Map or the state or local equivalent.
The City of Madison assumes no liability for any errors, omissions, or inaccuracies. The City also assumes no liability for any decisions or actions a user might take based on this map.