Flood Map Updates in Vermont

FEMA Region 1 has recently initiated the early stages of flood map updates in Vermont. 

In the Missisquoi River watershed, and adjacent Franklin and Orleans Counties, a draft Discovery Report is scheduled to be released by the spring of 2019.  This report will reflect feedback from state and municipal officials on the high risk flood hazard areas in their communities.  The report will identify flood risks determined by Base-Level Engineering, as well as the reaches flagged for detailed flood studies, and the priority products for delivery through the final Flood Insurance Rate Map.

Base-Level Engineering generates computer model-based Zone A flood maps.  Zone As are high risk Special Flood Hazard Areas that do not have published Base Flood Elevations.  This process requires high quality topographic data, such as the equivalent of two-foot contours, or better, from lidar.   Vermont now has acquired lidar across the state through a multi-agency partnership led by the Vermont Center for Geographic Information.  Much of this contour information, in one foot or two foot intervals, is available now in tile form through the VT Open Geodata Portal.  This fall, the new contour data will become conveniently available through web-based map tools.


Model-based Zone A maps provide a significant improvement in the quality of flood risk identification in places that otherwise have no maps, or hand-drawn Zone A maps.   In low density areas, model-based Zone A maps, can be incorporated directly into future updated Flood Insurance Rate Maps (FIRM).   Model-based Zone As were incorporated into the most recent Digital FIRM of 2015 in Bennington County.

Detailed studies require additional work to integrate details about bridge constrictions and other field-based data.  This level of study is typically focused on areas with more people living in or near floodplains.

Also in 2019, Discovery processes will begin for communities in the Deerfield and Lamoille watersheds.   Community officials will be invited to participate in meetings to discuss the map update process, and to articulate local flood mapping priorities.

The Flood Ready Atlas tinyurl.com/floodreadyatlas displays only officially-digitized Flood Insurance Rate Maps (DFIRMs).  A special layer on the Flood Ready Atlas indicates the current extent of Digital FIRMs and paper FIRMs.   All effective FIRMs can be viewed from the FEMA Map Service Center at www.msc.fema.gov

Flood Ready Vermont has more information on Flood Resilience, Flood Hazard Areas and Hazard Area Maps.