The Digital Flood Insurance Rate Map (DFIRM) Database depicts flood risk information and supporting data used to develop the risk data. The primary risk classifications used are the 1-percent-annual-chance flood event, the 0.2-percent-annual- chance flood event, and areas of minimal flood risk. The DFIRM Database is derived from Flood Insurance Studies (FISs), previously published Flood Insurance Rate Maps (FIRMs), flood hazard analyses performed in support of the FISs and FIRMs, and new mapping data, where available. The FISs and FIRMs are published by the Federal Emergency Management Agency (FEMA). Spatial data is georeferenced to the earth surface using the Transverse Mercator projected coordinate system and the North American Datum of 1983. The specifications for the horizontal control of DFIRM data files are consistent with those required for mapping at a scale of 1:6000.

This cached tiled map service, hosted by MassGIS, represents FEMA National Flood Hazard Layer (NFHL) data currently available for Massachusetts.

The National Flood Hazard Layer (NFHL) dataset represents the current effective flood risk data for those parts of the country where maps have been modernized by the Federal Emergency Management Agency (FEMA). It is a compilation of effective Flood Insurance Rate Map (FIRM) databases and any Letters of Map Revision (LOMR) that have been issued against those databases since their publication date. The NFHL is updated as new data reaches its designated effective date and becomes valid for regulatory use under the National Flood Insurance Program (NFIP).

See full metadata from MassGIS at http://www.mass.gov/anf/research-and-tech/it-serv-and-support/application-serv/office-of-geographic-information-massgis/datalayers/nfhl.html.

All data included in this layer are considered "final" by FEMA. Any preliminary data that appear on maps displayed at community meetings, etc., are not included here.

This map service includes data published by FEMA as of July 21, 2014.