Decatur, Georgia Begins New Flood Mapping

Please read the following letter from John F. Madajewski, P.E. if you perform work in the City of Decatur, Georgia. Maps can be viewed at the City of Decatur’s website: Click on the "Flood Plain Information" link at the bottom right corner of the home page:

The City of Decatur has undertaken a detailed engineering hydrology and hydraulics study to remap the floodplain of the four drainage basins within the city. The study is a partnership with FEMA and the Georgia Emergency Management Agency (GEMA) as part of the nationwide map modernization initiative. The new mapping was finalized by FEMA review in 2007 and became effective on Feb. 20, 2008. The remapping project inventoried and analyzed the runoff generated within each of the drainage basins to current FEMA standards and criteria. This information will be used to develop new floodplain limits for the Base Flood Elevation (BFE), the 100-year storm return frequency used by FEMA for all floodplain mapping. The BFE floodplain limit means the flood has a one-percent chance of being equaled or exceeded in any given year.
The city expanded its study to address future condition hydrology. Additional study has established the modeled limits of the floodplain to address the build-out state of development within the city in compliance with the zoning map approved by the City Commission. The new mapping eliminates all previously unstudied areas, shown as Zone A on the FIRM panel maps approved by FEMA in May 2001. The new floodplain map (see link below) can be used by individuals to view the extent of the floodplain’s impact on specific properties or within the city in general.
All elevation certificates produced or surveys conducted to establish the limits of the floodplain on specific parcels of land after Feb. 20, 2008 must utilize the data and elevation information contained within the approved Letter of Map Revision (LOMR) issued to the city by FEMA. The Flood Insurance Rate Map (FIRM) panel maps, Flood Insurance Study (FIS) profiles, and flow rate data issued by FEMA on May 7, 2001 have been superseded by the City’s LOMR.  Please open and review the complete LOMR information, data files, waterway profiles and FIRM panels list below that have the new map information approved by FEMA to obtain Base Flood Elevation (BFE) and any other data normally obtained from the superseded FIRM panels and FIS study. Copies of this information can be obtained from the Engineering Department. The cost of obtaining copies will be the cost of their reproduction.  Should you require additional information or clarification on the impact of the floodplain for any property within the city please contact John F. Madajewski, Senior Engineer for the Engineering Department at 404-377-6198 or by email @  Please provide this information to your membership for use in information to clients and for the individual members use in the City that may be seeking to acquire property and perform a survey that is impacted by the floodplain.

John F. Madajewski, P.E.Senior Engineer