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The County of DuPage
Wheaton, Illinois

County Mapping Update Overview

In 2008, DuPage County Stormwater Management received a $2,050,000.00 grant from the Federal Emergency Management Agency (FEMA) to restudy and remap the floodplains for 24 watersheds in DuPage County.  In cooperation with the Illinois State Water Survey (ISWS), this project will result in a new Countywide floodplain map updating the current FEMA Digital Flood Insurance Rate Map (DFIRM) map dated December 16, 2004.  

This countywide project incorporated new flood hazard information in the following watersheds: 

  • Salt Creek Mainstem and its tributaries that include Spring Brook, Devon Avenue, Westwood Creek, Ginger Creek, Sugar Creek, Oak Brook Tributary and Bronswood Tributary
  • East Branch DuPage River Mainstem and its tributaries that include Swift Meadows/Army Trail Road, Armitage Creek, Glencrest Creek, Tributary No. 2, Rott Creek, Lacey Creek, Prentiss Creek, St. Joseph Creek, Crabtree Creek and Willoway Brook
  • Steeple Run Tributary, Spring Brook No. 1
  • Sawmill Creek, Wards Creek  

The new study information has resulted in new and modified: base flood elevations, Special Flood Hazard Area (SFHA) boundaries, floodway boundaries, and food insurance zone designations.  The revision also incorporated non-revised flood hazard information from effective FIS reports, FIRMs and Flood Boundary and Floodway Maps as appropriate for the remaining watersheds in DuPage County.  Fifty-six Letters of Map Revision (LOMR) and one multi-lot Letter of Map Amendment (LOMA) were also incorporated.

FEMA Revised Preliminary Process 

Revised Preliminary FIRMs were released on June 1, 2017, and will be presented to the public and government officials at an Open House meeting on July 27, 2017. A 30-day comment period will begin on July 27, 2017. 

The next step in the process will be the 90-day appeal period. Appeals are technical challenges to the FIRM and require data on the part of the appellant. The criteria for appeal eligibility has changed since the 2004 DuPage FIRM was finalized. Out of the forty communities in DuPage County, thirty-eight will receive an appeal period; Batavia and St. Charles do not have Special Flood Hazard Area (SFHA) in DuPage County. The following four items are appealable:

  • New or revised Base Flood Elevations (BFEs) & base flood depths
  • New or revised Special Flood Hazard Area (SFHA) boundaries
  • Changes in SFHA zone designation
  • New or revised regulatory floodway boundaries

The Notice for the 90 day appeal period will be published in the Federal Register at the appropriate time. After the 30-day comment period and 90-day appeal periods have ended and all comments/appeals have been addressed, final preparation of the FIRM and FIS Report will be initiated. The new FIRM and FIS Report will become effective 7 to 10 months later.

Revised Preliminary DFIRM Map Compare Web Application

Stormwater Management and GIS staff have created a web application which allows the public to quickly compare the new preliminary data to the effective DuPage County DFIRMs. To visit this application, please follow this link,  Revised Preliminary DFIRM Map Compare

2017 Revised Preliminary DFIRM Map Viewer

Please use the mapping application below to find your preliminary map panel. Use the search field in the upper right hand corner to locate an address, intersection, or place name. When you have reached your desired location, please click on the map to view a thumbnail image of the panel. Click the image within the popup window to open a larger jpg which can then be saved.

Preliminary floodplain maps have also been posted online by FEMA and the ISWS.  Links to both sites are listed below: 

FEMA's site for Preliminary Data:  Click on the preliminary flood data search tool, "preliminary flood data search tool", then complete the drop down menu choices. (Illinois, DuPage County, Get Preliminary FEMA Map Products").  The ISWS hosted site will have jpegs of the panels at: