July 1997 (Download updated on 7/24/25)

This layer is sourced from maps.coast.noaa.gov.

This map service presents spatial information developed as part of the National Oceanic and Atmospheric Administration (NOAA) Office for Coastal Management’s Coastal Flood Exposure Mapper. The purpose of the online mapping tool is to provide coastal managers, planners, and stakeholders a preliminary look at exposures to coastal flooding hazards. The Mapper is a screening-level tool that uses nationally consistent data sets and analyses. Data and maps provided can be used at several scales to help communities initiate resilience planning efforts. Currently the extent of the Coastal Flood Exposure Mapper covers U.S. coastal areas along the Gulf of Mexico and Atlantic Ocean. NOAA provides the information “as-is” and shall incur no responsibility or liability as to the completeness or accuracy of this information. NOAA assumes no responsibility arising from the use of this information. For additional information, please contact the NOAA Office for Coastal Management (coastal.info@noaa.gov).

© NOAA Office for Coastal Management

The National Flood Hazard Layer (NFHL) data incorporates all Flood Insurance Rate Map (FIRM) databases published by the Federal Emergency Management Agency (FEMA), and any Letters Of Map Revision (LOMRs) that have been issued against those databases since their publication date. It is updated on a monthly basis. The FIRM Database is the digital, geospatial version of the flood hazard information shown on the published paper FIRMs.The FIRM 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 FIRM Database is derived from Flood Insurance Studies (FISs), previously published 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 FEMA.The NFHL is available as State or US Territory data sets. Each State or Territory data set consists of all FIRM Databases and corresponding LOMRs available on the publication date of the data set.The specification for the horizontal control of FIRM Databases is consistent with those required for mapping at a scale of 1:12,000. This file is georeferenced to the Earth's surface using the Geographic Coordinate System (GCS) and North American Dataum of 1983 (NSRS-2007).

For more information on FEMA's NFHL data, please visit their National Flood Hazard Layer website.

Flood zones - from FEMA

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).The data in this service was published by FEMA as of July 18, 2025 (Latest Study Effective Date = 07/08/2025; Latest LOMR Effective Date = 07/09/2025).Also see the Map Service and Feature Service.See full details.

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.

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 Wisconsin 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.

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).

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). In addition to the preceding, required text, the Abstract should also describe the projection and coordinate system as well as a general statement about horizontal accuracy.

This web map App was compiled by the Martha's Vineyard Commission (MVC) for planning purposes only. The flood data is provided by FEMA (effective 2016) and uploaded to ArcGIS Online by the MVC. Click here for more details about FEMA Flood Zones.For an official determination of whether or not a specific location is located within a Flood Hazard Ares, please visit FEMA's Map Service Center. This web map/App is provided for planning purposes only.The map also includes parcel boundaries and building outlines (the latter generated from roof outlines visible on aerial photos). The parcel data is assembled and published to ArcGIS OnLine by MassGIS. The online hosted data were last updated by MassGIS in May 2021. The parcel pop-up information is from a data extract from the respective town's assessing database. These data were current on date of extraction and may not reflect the most current assessing info. For the most current assessing info, please contact the Town's Assessing Office. The parcel boundaries and attribute table conform to the State's Level 3 Parcel Data Standard. See MassGIS for full details.The building outlines (roofprints) were created and then published as a tile layer (no site specific info available) by MassGIS.

The FIRM Database is the digital, geospatial version of the flood hazard information (location and attributes for boundaries of flood insurance risk zones) shown on the published paper Flood Insurance Rate Maps (FIRMs). The FIRM 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 FIRM Database is derived from Flood Insurance Studies (FISs), previously published 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 FEMA.The FIRM is the basis for floodplain management, mitigation, and insurance activities for the National Flood Insurance Program (NFIP). Insurance applications include enforcement of the mandatory purchase requirement of the Flood Disaster Protection Act, which "... requires the purchase of flood insurance by property owners who are being assisted by Federal programs or by Federally supervised, regulated or insured agencies or institutions in the acquisition or improvement of land facilities located or to be located in identified areas having special flood hazards, " Section 2 (b) (4) of the Flood Disaster Protection Act of 1973. In addition to the identification of Special Flood Hazard Areas (SFHAs), the risk zones shown on the FIRMs are the basis for the establishment of premium rates for flood coverage offered through the NFIP. The FIRM Database presents the flood risk information depicted on the FIRM in a digital format suitable for use in electronic mapping applications. The FIRM Database serves to archive the information collected during the Flood Risk Project.Informing Worcester is the City of Worcester's open data portal where interested parties can obtain public information at no cost.

The Massachusetts Sea Level Rise and Coastal Flooding Viewer was developed by the Massachusetts Office of Coastal Zone Management’s StormSmart Coasts Program. The flooding extents and water level elevations associated with sea level rise scenarios, current coastal flood zones, and hurricane surge models were developed by the National Oceanic and Atmospheric Administration (NOAA), Federal Emergency Management Agency (FEMA), and U.S. Army Corps of Engineers (USACE).The following community facilities and infrastructure were mapped: airports, commuter rail and subway stations, courthouses, dams, electrical generation facilities and substations, fire stations, harbormaster's offices, hospitals, landfills, libraries, lighthouses, long-term care residences, police stations, prisons, public colleges and universities, public water supply sources, schools (kindergarten through high school), town/city halls, municipal wastewater treatment plants, and water supply protection areas and wellheads. Public facilities and infrastructure located inland of mapped coastal flooding areas are not included in the viewer.The infrastructure layers shown in the viewer are web services hosted and updated by state and federal agencies and regional organizations such as the Massachusetts Bureau of Geographic Information (MassGIS) and Northeast Ocean Data. This product should not be used for legal, engineering, or surveying purposes. Site-specific assessments of elevations or boundaries (parcel, structure, or other) should be made by a certified survey professional.

Authority: Executive Order No. 149: FEMA and Flood Plain Use. Jurisdiction: Floodplains in the Commonwealth of Massachusetts. Applicability: Construction by state agencies must avoid floodplains. State-administered grant and loan programs must avoid supporting construction in flood plains, to the extent possible. Regulatory Designates the Massachusetts Department of Conservation and Recreation (DCR, formerly the Department of Environmental Management) as the state coordinating agency to implement the National Flood Insurance Program. Requires all state agencies, to the extent possible, to avoid construction, provision of loans or grants, conveying, or permitting projects in floodplains. Provides for Massachusetts participation in the National Flood Insurance Program. Review Process: Contact the Federal Emergency Management Agency (FEMA) to determine if a proposed project is in a floodplain. Projects proposed in floodplains are reviewed in conjunction with Massachusetts Environmental Policy Act (15), Massachusetts Wetlands Protection Act (17), and Massachusetts Office of Coastal Zone Management (22) reviews. Technical assistance is also available from the DCR Flood Hazard Management Program. Forms: No additional forms for floodplain review. Fees No additional fees for floodplain review. Website: FEMA at http://store.msc.fema.gov/webapp/wcs/stores/servlet/FemaWelcomeView?storeId=10001&catalogId=10001&langId=-1 DCR Flood Hazard Management Program at http://www.mass.gov/dcr/stewardship/mitigate/.

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).

Data layers in this child item include high-water mark and storm-sensor data collected by the U.S. Geological Survey (USGS) New England Water Science Center following the January 4, 2018, and March 2-4, 2018, winter-storm events in New England. High-water marks and continuous water-level sensor data range from Portland, Maine, to Provincetown, Massachusetts, and reference the North American Vertical Datum of 1988 (NAVD88). For more information about these storm events and the data collection, please see Bent, G.C., and Taylor, N.J., 2020, Total water level data from the January and March 2018 nor’easters for coastal areas of New England: U.S. Geological Survey Scientific Investigations Report 2020–5048, 47 p., accessed June 3, 2021, at https://doi.org/10.3133/sir20205048 Flood-inundation map layers and interim products used to create them also are included in this child item. The USGS polygon of the stillwater-inundation map reflects a statistical storm with a 1-percent annual exceedance probability from Portland, Maine, to Provincetown, Massachusetts, based on coastal tide-gage data. The January and March 2018 inundation maps are polygon shapefiles of estimated flood extent derived from the high-water mark and storm-sensor data following the storm events. The flood extents and water-surface elevations were derived from simplified estimations of high-water mark and storm-sensor data and delineated using 2-meter-resolution lidar digital-elevation models. Interim data layers that were used to create the flood-inundation polygons include a coastal flood-profile line and coastal watershed boundaries. The compressed zip files contain ESRI shapefiles that include xml metadata files. Detailed processing steps are documented in the metadata for each layer. See the Scientific Investigation Report associated with this data release for more information.

Effective (2017) and Preliminary (2023) FEMA Flood Zones for Arlington, MA and the changes between the data

This EnviroAtlas dataset describes the total counts and percentage of population, land area, and impervious surface in the 1% Annual Chance Flood Hazard area or 0.2% Annual Chance Flood Hazard area of each block group. The flood hazard area is defined by the National Flood Hazard Layer (NFHL) produced by the Federal Emergency Management Agency (FEMA, www.fema.gov). This dataset was produced by the US EPA to support research and online mapping activities related to EnviroAtlas. EnviroAtlas (https://www.epa.gov/enviroatlas) allows the user to interact with a web-based, easy-to-use, mapping application to view and analyze multiple ecosystem services for the contiguous United States. The dataset is available as downloadable data (https://edg.epa.gov/data/Public/ORD/EnviroAtlas) or as an EnviroAtlas map service. Additional descriptive information about each attribute in this dataset can be found in its associated EnviroAtlas Fact Sheet (https://www.epa.gov/enviroatlas/enviroatlas-fact-sheets).

NFHL with Q3 data only where no NFHL data exist. Neither dataset is available in Franklin county. See the MassGIS metadata pages for more information abut FEMA Q3 and NFHL data.