Welcome to the East River Collaborative interactive flood map. This tool allows you to view and compare the impacts of different flood scenarios in the East River watershed.
Disclaimer:
Due to a lack of calibration data, this map should be used strictly as a planning reference tool and not for navigation, permitting, or other legal purposes.
Background: The East River flows north from Calumet County for over 40 miles through Brown County and 13 municipalities before entering the Fox River, which empties into the Bay of Green Bay on Lake Michigan. This map shows the scale of potential flooding at various precipitation and Lake Michigan water level scenarios based on data from an East River flood modeling study led by the University of Wisconsin-Madison Department of Civil and Environmental Engineering. Stream gauges were placed along the East River and its tributaries in 2020 and 2021 to collect hydrologic and hydraulic data. Flood scenarios were analyzed using the HEC-HMS and one-dimensional HEC-RAS models and informed by the river flow data and 2010 Brown County LiDAR. An additional modeling scenario shows the results of a two-dimensional flood model of the entire watershed conducted by Westwood Professional Services using the modeling software FLO-2D.
How to Use this Map
Select a Display:
Extent shows the flooded area for the selected rainfall and lake level. Depth shows how deep the flood water is in feet.
Select a Lake Level:
The extent and depth of flooding depends in part on Lake Michigan water levels. High shows flooding based on record high water levels; Low shows flooding based on record low water levels. Compare enables a swipe tool to compare flooding between the high and low lake levels.These two lake levels are the record high daily average level (583.8 ft IGLD 1985 set on 5/19/2020) and record low daily average level (575.7 ft IGLD 1985 set on 10/27/2010) measured at the Green Bay NOAA CO-OPS water level station 9087079. IGLD 1985 is the International Great Lakes Datum of 1985, which is the elevation reference system used to define water levels in the Great Lakes.
Select Rainfall Amount:
Choose a rainfall amount to see where flooding would happen for the selected lake level. 2.1” in 24 hours has a 99.9% chance to happen at least once per year (1-year storm). 3.4” in 24 hours has a 10% annual chance occurrence (10-year storm). 5.4” in 24 hours has a 1% annual chance occurrence (100-year storm). 7.2” in 24 hours has a 0.2% annual chance occurrence (500-year storm). Rainfall statistics are based on NOAA Atlas 14. All results are from a 1-D HEC-RAS model unless noted to be from a 2-D model (FLO-2D).
Add Data Layers:
You are able to enhance the map with additional data layers.
The Impacted Buildings layers show which buildings may be damaged by a flood at the selected rainfall and lake level. These data layers were developed by the UW-Madison Space Science and Engineering Center using FEMA’s Hazus software.
The Social Vulnerability Index layer shows which areas might need more help after a flood because of factors like income, demographics, and housing characteristics. Social Vulnerability was computed for census block groups with data from the U.S. Census and the Wisconsin Statewide Parcel Map using methodology of the Center for Disease Control and the University of South Carolina’s Hazards and Vulnerability Research Institute.
The Infrastructure layer shows community assets and infrastructure.
Funding for the development of this mapping tool was provided by the National Oceanic and Atmospheric Administration Sea Grant Support and the Fund for Lake Michigan. Data used in the mapping tool was created with additional funding from the Wisconsin Coastal Management Program and the National Oceanic and Atmospheric Administration Office of Coastal Management. Map composed by the UW-Madison Cartography Lab, and in collaboration with UW Sea Grant, © 2024.