Proposed FIRMs

St. Louis County in partnership with the Missouri State Emergency Management Agency (SEMA) and Federal Emergency Management Agency (FEMA), is updating the Flood Insurance Rate Maps (FIRMs) and the Flood Insurance Study (FIS) report within the City of Chesterfield under FEMA’s Risk Mapping, Assessment, and Planning (Risk MAP) program. Risk MAP is a FEMA program that helps communities identify, assess and reduce their flood risk.

In order to view the proposed changes to the FIRMs, please visit the following website: To view the changes to the floodplain and floodway, please complete the following steps:     

  1. Zoom to your property within St. Louis County and the City of Chesterfield.
  2. At the bottom middle of the screen, there are four buttons.  Click on the Layer List, which is the second button from the left.
  3. Check the Flood Study Review Box and the drop down arrow to the left.
  4. Uncheck all boxes under Flood Study Review and check Changes since Last Firm (Floodway) and Changes Since Last Firm (100yr) to view the proposed changes.  Then click on the Legend button (far left button of the bottom four) to display the legend showing corresponding colors of increase, no change, or decrease to the floodplain (100yr) or floodway. 

Below is a timeline of past events regarding the proposed FIRMs:

August 20, 2021: 
The preliminary FIRMs were tentatively scheduled to be issued on August 16, 2021.  Staff received an update from SEMA indicating that the FIRM panels have been created and SEMA is in the final stages of coordination with levee districts in St. Louis County.  The revised projected date for issuance of preliminary FIRMs is now January 2022.

May 24, 2021:  The preliminary FIRMs were tentatively scheduled to be issued in the April/May time frame.  Staff received an update from SEMA that due to community discussions that have taken place over the last couple months, the preliminary FIRM issuance date has been revised.  The projected date for issuance of preliminary FIRMs is now August 16, 2021.

February 16, 2021 - The preliminary FIRMs were tentatively scheduled to be issued on February 19, 2021.  Staff received an update from SEMA indicating that the preliminary FIRMs are still being reviewed and will not be ready for issuance on February 19, 2021.  SEMA anticipates that the preliminary FIRMs will be issued in the April/May time frame.

September 9, 2020:SEMA issued an update indicating that a tentative date of February 19, 2021 has been set for issuance of the Preliminary FIRMs.  A link to the update is posted below:
St. Louis County Preliminary FIRMs

February 6 & 7, 2019
 – City Staff attended meetings regarding the proposed mapping changes conducted by SEMA and its consultant, Wood Environmental & Infrastructure Solution. Cities were told that the Preliminary FIRMs are scheduled to be completed in September of 2019, at which time they will be submitted to the affected communities.  A formal comment and appeal period of 90 days is expected to begin in the winter of 2020, after the preliminary maps are distributed.  Details on the appeal process will be provided once they become available.  New Effective FIRMs are expected to be formally issued in two to three years.   

October 15, 2018 – Deadline for preliminary comments to be posted to the SEMA website:

September 14, 2018 – The City of Chesterfield sent a post card notification to property owners within 200 feet of a proposed change in the floodplain. This notification provided property owners the chance to comment on the proposed maps.   

August 28, 2018 – Initial meeting with SEMA introducing a St. Louis County wide flood study within St. Louis County, including the City of Chesterfield. Flood Study Review Maps are available for comment through the Website.

If you have any questions, please contact Jeff Paskiewicz, Senior Civil Engineer at or by phone at 636-537-4759.