Floodplain Management

City of Green Bay Floodplain Brochure

City of Green Bay Interactive Parcel Map 
Search or zoom to parcel and use interactive layers in the top-left corner tool bar.

City of Green Bay Zoning Code, Section 13-300


Floodsmart Website

Current Water Data for Wisconsin

NOAA Real-Time Flooding Gauges

Coping with Flooding

Wisconsin Floodplain Management 

USGS Stream Site and Water Watch


Questions? Contact the Planning Department at (920) 448-3400 or contact your local FEMA representative here.




Flood Protection

Flood Protection Information

Believe it or not, Green Bay has experienced substantial flooding in the past and will again in the future.  The primary source of this flooding is the high water level of the bay affecting the Fox River, the East River, Mahon Creek, and many smaller creeks and drainage ways.  Intense rainfalls, rapid thawing of ice and snow, and ice dams also cause flooding in areas of the City that normally do not experience flooding.  This is intended to answer some of your questions and offer ideas on what to do in case flooding is a concern to you.

Flood Risk Potential:  Are you aware of your risk for flooding?

Areas adjacent to the bay, rivers, streams, creeks, and drainage ways serve as temporary storage areas for high water.  If you live near or inside one of these areas, you more than likely will be impacted by the high bay levels.  Do you know what measures are needed to protect your property from flooding?

There are many relatively flat areas of the City and areas having unusual drainage patterns.  If you live downslope of an area that drains near or through your property, you could be at risk for flooding.  Would you like to learn more about localized flooding and how to protect your property?

Our parkways, ditches, and stream banks provide effective drainage controls from flooding by providing storage areas for high water or flooding conditions.  However, when people dump or throw garbage, grass clippings, leaves, brush, fallen trees, or other debris in them, drainage ways can become potential sources for flooding.  If you live near a drainage way, report any debris in these areas, and of course, DO NOT DUMP or throw anything into them as it is a violation of Green Bay’s Municipal Ordinance.

City Services:  Did you know that City services are free?

Stop in the Inspection Division office in Room 608 of City Hall at 100 N. Jefferson Street to see if your property is located in one of the mapped Special Flood Hazard Areas.  If it is, you can obtain handouts or talk with an inspector about protecting your property from flooding.

If you would like someone to visit your property to help evaluate your risk of flooding and explain possible ways of stopping or lessening the effects of damage, call the Inspection Division office at (920) 448-3300.

The City periodically inspects the parkways, streams, and drainage ways for accumulations of debris and blockages.  If you have questions about them or wish to report a blocked drainage way, call the Operations Division at (920) 448-3535.

Protecting Your Property

There are several ways to protect a building from flood damage.  Keep flood waters away from your building by re-grading your lot or building a floodwall or earthen berm around your property.  These methods work if your lot is large enough, the flood depth is not too deep, and the property is not in a channel or floodway.

You can also waterproof foundation walls and seal up openings below flood levels, such as windows.  This can be done by replacing them with glass blocks or by raising window wells above potential water levels.

A more permanent solution is to raise the house above flood levels.  A small woodframe house can be elevated for approximately $10,000.  Sound crazy?  Check out the house at 601 Hartung Street.  This house was moved to that location and set on a new foundation that is two feet above the base flood elevation for the area.

Rain and groundwater is clear water that must be kept out of sanitary sewers by law, also known as clear water separation.  Clear water illegally entering sanitary sewers surcharges the sewers during heavy rains, increasing the potential for basement flooding.  Many houses, even those not in a floodplain, have sewers which back up into the basement because of surcharged sewers.  During the 1990 flood, most of the reported basement flooding resulted from water backing up through basement floor drains or from overflowing fixtures located in the basements.  Compounding the problem, electrical power outages left many sump pumps without power and water-filled basements.

Proper installation and maintenance of backwater valves for plumbing fixtures installed below sidewalk grade can help prevent sewer backups.  Backwater valves can be purchased at your local hardware store, or you can talk to a plumbing contractor about installing one for you.

These measures are called floodproofing or retrofitting.  It is important to note that alterations to your building or land may require permits.  Even regrading or filling in the floodplain requires plan approval and land-use permits.

If you are warned of possible flooding, it’s important to take action early.  Shut off gas and electricity and move valuable contents to high ground if possible.  It is unlikely that you will get much advance warning so make a detailed checklist in advance to help ensure you don’t forget anything.

More information can be found at the FEMA >> website.