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Understanding flood hazard areas

Last updated: 7/17/16

Understanding flood hazard areas

Floodplains are areas of land susceptible to inundation by floodwaters.

Special Flood Hazard Areas (SFHA) are flood plains that adjoin a river, stream, or other inland or coastal waterway that are inundated by water during the 1 percent annual chance flood (100-year flood). The 1 percent annual chance flood is a flood event having a 1 percent chance of being equaled or exceeded in magnitude in any given year. 

SFHAs are considered a Wetland Resource Area under the Massachusetts Wetlands Protection Act and are depicted on Federal Emergency Management (FEMA) Flood Insurance Rate Maps (FIRM) as Zones A, AE, AH, AO, AR, A99, V and VE. 

Still have questions? Contact:
1 City Hall Square
Room 709
Boston, MA 02201-2031
United States

Changes to flood insurance and maps

Changes to the Flood Insurance Rate Maps for the City of Boston went into effect on March 16, 2016.

The Federal Emergency Management Agency (FEMA) has been revising flood maps to reflect current flood risks in coastal areas nation-wide over the last few years. The revisions use historical data and advanced modeling technology to more accurately determine current flood risks. The revised maps do not account for future flooding risks. The official map of a community and its flood hazards is known as a Flood Insurance Rate Map (FIRMs).

The revised maps provide more information about flood risks for new and existing development. Boston adopts these maps so property owners can qualify to purchase and maintain federally subsidized flood insurance through the National Flood Insurance Program (NFIP). The City of Boston is also eligible to receive federal disaster assistance in the case of a flood emergency by adopting the FIRMs.

The updated FIRMs for Boston are available at the FEMA Map Service Center. For assistance in understanding the FEMA FIRMs, and to find out if your property will be affected by remapping, see the FEMA MSC How-to guide here and read the resources below.

More information

More information

FEMA provides basic flood insurance information for claims adjusters, property owners, insurance professionals, lenders, both state and local officials, and surveyors.

The StormSmart Coasts program is designed to:

  • assist communities and people working and living on the coast by providing information, strategies, and tools to help address challenges arising from erosion, flooding, storms, sea level rise, and other climate change impacts, and
  • promote effective management of coastal landforms, such as beaches and dunes.

Their publications include materials on coastal erosion, flooding, storms, and sea level rise, as well as other publications on coastal geology.