THIS LAYER IS HOSTED BY FEMA, not NAPSG Foundation. We are simply pointing to their layer with this ArcGIS Online item. The National Flood Hazard Layer (NFHL) dataset represents the current effective flood data for the country, where maps have been modernized. It is a compilation of effective Flood Insurance Rate Map (FIRM) databases and Letters of Map Change (LOMCs). The NFHL is updated as studies go effective. For more information, visit FEMA's Map Service Center (MSC). You can view this information in a standalone viewer here: https://hazards-fema.maps.arcgis.com/apps/webappviewer/index.html?id=8b0adb51996444d4879338b5529aa9cdREST URL: https://hazards.fema.gov/gis/nfhl/rest/services/public/NFHL/MapServerBase Map ConsiderationsThe default base map is from an ESRI service and conforms to FEMA's specification for horizontal accuracy. This base map is composed of the orthoimagery used when the Flood Insurance Rate Maps (FIRMs) were initially created combined with standard imagery products managed by ESRI. This map should be considered the best online resource to use for official National Flood Insurance Program (NFIP) purposes when determining locations in relation to regulatory flood hazard information. If a different base map is used with the NFHL, the accuracy specification may not be met and the resulting map should be used for general reference only, and not official NFIP purposes.Further InformationFor more flood map data, tool, and viewing options, visit the FEMA NFHL page.Several fact sheets are available to help you learn more about FEMA’s NFHL utility: National Flood Hazard Layer (NFHL) GIS Services Users GuideNational Flood Hazard Layer (NFHL): New Products and Services for FEMA's Flood Hazard Map DataNFHL GIS Data: Perform Spatial Analyses and Make Custom Maps and Reports

FEMA provides access to the National Flood Hazards Layer (NFHL) through web mapping services. The maps depict effective flood hazard information and supporting data. The primary flood hazard classification is indicated in the Flood Hazard Zones layer.The NFHL layers include:Flood hazard zones and labelsRiver Miles MarkersCross-sections and coastal transects and their labelsLetter of Map Revision (LOMR) boundaries and case numbersFlood Insurance Rate Map (FIRM) boundaries, labels and effective datesCoastal Barrier Resources System (CBRS) and Otherwise Protected Area (OPA) unitsCommunity boundaries and namesLeveesHydraulic and flood control structuresProfile and coastal transect baselinesLimit of Moderate Wave Action(LiMWA)Not all effective Flood Insurance Rate Maps (FIRM) have GIS data available. To view a list of available county and single-jurisdiction flood study data in GIS format and check the status of the NFHL GIS services, please visit the NFHL Status Page.Preliminary & Pending National Flood Hazard LayersThe Preliminary and Pending NFHL dataset represents the current pre-effective flood data for the country. These layers are updated as new preliminary and pending data becomes available, and data is removed from these layers as it becomes effective.For more information, please visit FEMA's website.To download map panels or GIS Data, go to: NFHL on FEMA GeoPlatform.Preliminary & Pending DataPreliminary data are for review and guidance purposes only. By viewing preliminary data and maps, the user acknowledges that the information provided is preliminary and subject to change. Preliminary data are not final and are presented in this national layer as the best information available at this time. Additionally, preliminary data cannot be used to rate flood insurance policies or enforce the Federal mandatory purchase requirement. FEMA will remove preliminary data once pending data are available.Pending data are for early awareness of upcoming changes to regulatory flood map information. Until the data becomes effective, when it will appear in FEMA's National Flood Hazard Layer (NFHL), the data should not be used to rate flood insurance policies or enforce the Federal mandatory purchase requirement. FEMA will remove pending data once effective data are available.To better understand Preliminary data please see the View Your Community's Preliminary Flood Hazard Data webpage.FEMA GeoPlatformFEMA's GIS flood map services are available through FEMAs GeoPlatform, an ArcGIS Online portal containing a variety of FEMA-related data.To view the NFHL on the FEMA GeoPlatform go to NFHL on FEMA GeoPlatform.To view the Preliminary and Pending national layers on the FEMA Geoplatform go to FEMA's Preliminary & Pending National Flood Hazard Layer.Technical InformationFlood hazard and supporting data are developed using specifications for horizontal control consistent with 1:12,000–scale mapping. If you plan to display maps from the NFHL with other map data for official purposes, ensure that the other information meets FEMA’s standards for map accuracy.The minimum horizontal positional accuracy for base map hydrographic and transportation features used with the NFHL is the NSSDA radial accuracy of 38 feet. United States Geological Survey (USGS) imagery and map services that meet this standard can be found by visiting the Knowledge Sharing Site (KSS) for Base Map Standards (420). Other base map standards can be found at https://riskmapportal.msc.fema.gov/kss/MapChanges/default.aspx. You will need a username and password to access this information.The NFHL data are from FEMA’s FIRM databases. New data are added continually. The NFHL also contains map changes to FIRM data made by LOMRs.The NFHL is stored in North American Datum of 1983, Geodetic Reference System 80 coordinate system, though many of the NFHL GIS web services support the Web Mercator Sphere projection commonly used in web mapping applications.Organization & DisplayThe NFHL is organized into many data layers. The layers display information at map scales appropriate for the data. A layer indicating the availability of NFHL data is displayed at map scales smaller than 1:250,000, regional overviews at map scales between 1:250,000 and 1:50,000, and detailed flood hazard maps at map scales of 1:50,000 and larger. The "Scalehint" item in the Capabilities file for the Web Map Service encodes the scale range for a layer.In addition, there are non-NFHL datasets provided in the GIS web services, such as information about the availability of flood data and maps, the national map panel scheme, and point locations for LOMA and LOMR-Fs. The LOMA are positioned less accurately than are the NFHL data.Layers in the public NFHL GIS services:Use the numbers shown below when referencing layers by number.0. NFHL Availability1. LOMRs2. LOMAs3. FIRM Panels4. Base Index5. PLSS6. Toplogical Low Confidence Areas7. River Mile Markers8. Datum Conversion Points9. Coastal Gages10. Gages11. Nodes12. High Water Marks13. Station Start Points14. Cross-Sections15. Coastal Transects16. Base Flood Elevations17. Profile Baselines18. Transect Baselines19. Limit of Moderate Wave Action20. Water Lines21. Coastal Barrier Resources System Area22. Political Jurisdictions23. Levees24. General Structures25. Primary Frontal Dunes26. Hydrologic Reaches27. Flood Hazard Boundaries28. Flood Hazard Zones29. Submittal Information30. Alluvial Fans31. Subbasins32. Water Areas

Map service that provides a legend for the FEMA National Flood Hazard Layer. Display this along with the FEMA NFHL tiled map service at https://tiles.arcgis.com/tiles/hGdibHYSPO59RG1h/arcgis/rest/services/FEMA_National_Flood_Hazard_Layer/MapServer (metadata at https://massgis.maps.arcgis.com/home/item.html?id=630c74171705455592a8fa947c3f849f), which, being a tiled service hosted at ArcGIS Online, does not have a legend associated with it when displayed in ArcGIS Online or ArcGIS for Desktop.

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.

This cached tiled map service, hosted at MassGIS' ArcGIS Online site, represents FEMA National Flood Hazard Layer (NFHL) data currently available for Massachusetts. At scales 1:80,000 and closer, flood zone abbreviation labels appear (from the FLD_ZONE field). 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.

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 2, 2023.

To display a legend for this layer, add https://massgis.maps.arcgis.com/home/item.html?id=8455678914e64b03b565b97d07577279 to your map along with this service

THIS LAYER IS HOSTED BY FEMA, not NAPSG Foundation. We are simply pointing to their layer with this ArcGIS Online item. The National Flood Hazard Layer (NFHL) dataset represents the current effective flood data for the country, where maps have been modernized. It is a compilation of effective Flood Insurance Rate Map (FIRM) databases and Letters of Map Change (LOMCs). The NFHL is updated as studies go effective. For more information, visit FEMA's Map Service Center (MSC). You can view this information in a standalone viewer here: https://hazards-fema.maps.arcgis.com/apps/webappviewer/index.html?id=8b0adb51996444d4879338b5529aa9cdREST URL: https://hazards.fema.gov/gis/nfhl/rest/services/public/NFHL/MapServerBase Map ConsiderationsThe default base map is from an ESRI service and conforms to FEMA's specification for horizontal accuracy. This base map is composed of the orthoimagery used when the Flood Insurance Rate Maps (FIRMs) were initially created combined with standard imagery products managed by ESRI. This map should be considered the best online resource to use for official National Flood Insurance Program (NFIP) purposes when determining locations in relation to regulatory flood hazard information. If a different base map is used with the NFHL, the accuracy specification may not be met and the resulting map should be used for general reference only, and not official NFIP purposes.Further InformationFor more flood map data, tool, and viewing options, visit the FEMA NFHL page.Several fact sheets are available to help you learn more about FEMA’s NFHL utility: National Flood Hazard Layer (NFHL) GIS Services Users GuideNational Flood Hazard Layer (NFHL): New Products and Services for FEMA's Flood Hazard Map DataNFHL GIS Data: Perform Spatial Analyses and Make Custom Maps and Reports

Sourced directly from FEMA in 2019.

Purpose: This is an ArcGIS Pro template that GIS Specialists can use to identify vulnerable populations and special needs infrastructure most at risk to flooding events.How does it work?Determine and understand the Place Vulnerability (based on Cutter et al. 1997) and the Special Needs Infrastructure for an area of interest based on Special Flood Hazard Zones, Social Vulnerability Index, and the distribution of its Population and Housing units. The final product will be charts of the data distribution and a Hosted Feature Layer. See this Story Map example for a more detailed explanation.This uses the FEMA National Flood Hazard Layer as an input (although you can substitute your own flood hazard data), check availability for your County before beginning the Task: FEMA NFHL ViewerThe solution consists of several tasks that allow you to:Select an area of interest for your Place Vulnerability Analysis. Select a Hazard that may occur within your area of interest.Select the Social Vulnerability Index (SVI) features contained within your area of interest using the CDC’s Social Vulnerability Index (SVI) – 2016 overall SVI layer at the census tract level in the map.Determine and understand the Social Vulnerability Index for the hazard zones identified within you area of interest.Identify the Special Needs Infrastructure features located within the hazard zones identified within you area of interest.Share your data to ArcGIS Online as a Hosted Feature Layer.FIRST STEPS:Create a folder C:\GIS\ if you do not already have this folder created. (This is a suggested step as the ArcGIS Pro Tasks does not appear to keep relative paths)Download the ZIP file.Extract the ZIP file and save it to the C:\GIS\ location on your computer. Open the PlaceVulnerabilityAnalysis.aprx file.Once the Project file (.aprx) opens, we suggest the following setup to easily view the Tasks instructions, the Map and its Contents, and the Databases (.gdb) from the Catalog pane.The following public web map is included as a Template in the ArcGIS Pro solution file: Place Vulnerability Template Web MapNote 1:As this is a beta version, please take note of some pain points:Data input and output locations may need to be manually populated from the related workspaces (.gdb) or the tools may fail to run. Make sure to unzip/extract the file to the C:\GIS\ location on your computer to avoid issues.Switching from one step to the next may not be totally seamless yet.If you are experiencing any issues with the Flood Hazard Zones service provided, or if the data is not available for your area of interest, you can also download your Flood Hazard Zones data from the FEMA Flood Map Service Center. In the search, use the FEMA ID. Once downloaded, save the data in your project folder and use it as an input.Note 2:In this task, the default hazard being used are the National Flood Hazard Zones. If you would like to use a different hazard, you will need to add the new hazard layer to the map and update all query expressions accordingly.For questions, bug reports, or new requirements contact pdoherty@publicsafetygis.org

On January 25, 2018 FEMA replaced this map with a new NFHL map with additional functionality which allows users to print official flood maps. On April 1, 2018 this map and NFHL link will no longer function. Please update your bookmark to https://hazards-fema.maps.arcgis.com/apps/webappviewer/index.html?id=8b0adb51996444d4879338b5529aa9cd. For more information on NFHL data availability, please visit the NFHL GIS Services page at https://hazards.fema.gov/femaportal/wps/portal/NFHLWMSAs of August 1, 2017 all FEMA systems will require the use of the “https” protocol, and “http” links will no longer function. This may impact NFHL web services. The FEMA GeoPlatform (including this map) will not be affected by this change. For more information on how NFHL GIS services will be impacted, please visit the NFHL GIS Services page at https://hazards.fema.gov/femaportal/wps/portal/NFHLWMS.An NFHL FIRMette print service is now available HERE. (For a video tutorial, click here.)OverviewThe National Flood Hazard Layer (NFHL) dataset represents the current effective flood data for the country, where maps have been modernized. It is a compilation of effective Flood Insurance Rate Map (FIRM) databases and Letters of Map Change (LOMCs). The NFHL is updated as studies go effective. For more information, visit FEMA's Map Service Center (MSC). Base Map ConsiderationsThe default base map is from a USGS service and conforms to FEMA's specification for horizontal accuracy. This base map from The National Map (TNM) consists of National Agriculture Imagery Program (NAIP) and high resolution orthoimagery (HRO) that combine the visual attributes of an aerial photograph with the spatial accuracy and reliability of a map. This map should be considered the best online resource to use for official National Flood Insurance Program (NFIP) purposes when determining locations in relation to regulatory flood hazard information. If a different base map is used with the NFHL, the accuracy specification may not be met and the resulting map should be used for general reference only, and not official NFIP purposes. Users can download a simplified base map from the USGS service via: https://viewer.nationalmap.gov/services/ For the specifics of FEMA’s policy on the use of digital flood hazard data for NFIP purposes see: http://www.fema.gov/library/viewRecord.do?id=3235Letter of Map Amendment (LOMA) pointsLOMA point locations are approximate. The location of the LOMA is referenced in the legal description of the letter itself. Click the LOMA point for a link to the letter (use the arrows at the top of the popup window to bring up the LOMA info, if needed).This LOMA database may include LOMAs that are no longer effective. To be certain a particular LOMA is currently valid, please check relevant documentation at https://msc.fema.gov/ . Relevant documents can be found for a particular community by choosing to "Search All Products", and finding the community by State and County. Documents include LOMAs found in the "Effective Products" and "LOMC" folders, as well as Revalidations (those LOMAs which are still considered to be effective after a map is revised).Updates3/27/2017 - Updated all references to https to prevent issues with mixed content.5/11/2016 - Added link to NFHL FIRMette Print Service. Updated LOMA and CBRS popup notes.2/20/2014 - Created a General Reference map for use when the USGS base map service is down. Renamed this map to "Official".Further InformationSpecific questions about FEMA flood maps can be directed to FEMAMapSpecialist@riskmapcds.comFor more flood map data, tool, and viewing options, visit the FEMA NFHL page. Information about connecting to web map services (REST, WMS, WFS) can be found here.Several fact sheets are available to help you learn more about FEMA’s NFHL utility: National Flood Hazard Layer (NFHL) GIS Services Users GuideNational Flood Hazard Layer (NFHL): New Products and Services for FEMA's Flood Hazard Map DataMoving to Digital Flood Hazard Information Standards for Flood Risk Analysis and MappingNFHL GIS Data: Perform Spatial Analyses and Make Custom Maps and Reports

The National Flood Hazard Layer (NFHL) is a compilation of GIS data that comprises a nationwide digital Flood Insurance Rate Map. The GIS data and services are designed to provide the user with the ability to determine the flood zone, base flood elevation, and floodway status for a particular location. It also has information about the NFIP communities, map panels, cross sections, hydraulic structures, Coastal Barrier Resource System, and base maps such as road, stream, and public land survey data. Through flood studies, FEMA produces Flood Insurance Study Reports, FIRM Panels, and FIRM Databases. FIRM Databases that become effective are incorporated into the NFHL. Updates to the NFHL are issued through Letters of Map Revision (LOMRs) and Letters of Map Amendment (LOMAs). Continuously updated, the NFHL serves as a Digital Flood Insurance Rate Map representing the current effective flood data for those communities where maps have been digitized. NFHL data can be viewed with widely available GIS software, including freely available programs that work with GIS shapefiles. For more information on the NFHL, see the online resources referenced herein. Using base maps: The minimum horizontal positional accuracy for base map hydrographic and transportation features used with the NFHL is the NSSDA radial accuracy of 38 feet. Letter of Map Amendment (LOMA) point locations are approximate. The location of the LOMA is referenced in the legal description of the letter itself. LOMA points can be viewed in the NFHL Interactive Map on the FEMA GeoPlatform.

This is a MD iMAP hosted service. Find more information on http://imap.maryland.gov. The DFIRM Database presents the flood risk information depicted on a given Flood Insurance Rate Map (FIRM) in a digital format suitable for use in electronic mapping applications. The DFIRM database is a subset of the Digital Flood Insurance Study (FIS) database that serves to archive the information collected during the FIS. This map service is a composite of Effective and Preliminary floodplain data. Q3 data is used where neither Effective or Preliminary data is available for a given community. 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 specifications for the horizontal control of DFIRM data files are consistent with those required for mapping at a scale of 1:12 - 000. Last Updated: 03/2016 Map Service Link: http://geodata.md.gov/imap/rest/services/Hydrology/MD_Floodplain/FeatureServer ADDITIONAL LICENSE TERMS: The Spatial Data and the information therein (collectively "the Data") is provided "as is" without warranty of any kind either expressed implied or statutory. The user assumes the entire risk as to quality and performance of the Data. No guarantee of accuracy is granted nor is any responsibility for reliance thereon assumed. In no event shall the State of Maryland be liable for direct indirect incidental consequential or special damages of any kind. The State of Maryland does not accept liability for any damages or misrepresentation caused by inaccuracies in the Data or as a result to changes to the Data nor is there responsibility assumed to maintain the Data in any manner or form. The Data can be freely distributed as long as the metadata entry is not modified or deleted. Any data derived from the Data must acknowledge the State of Maryland in the metadata.

The Effective Floodplain layer represents the official regulatory floodplain as adopted by FEMA and a given local community for the National Flood Insurance Program (NFIP). Effective data should be used wherever it is available, but it is not available statewide.This is a MD iMAP hosted service. Find more information at https://imap.maryland.gov.Feature Service Link:https://mdgeodata.md.gov/imap/rest/services/Hydrology/MD_Floodplain/FeatureServer/1**Please note, due to the size of this dataset, you may receive an error message when trying to download the dataset. You can download this dataset directly from MD iMAP Services at: https://mdgeodata.md.gov/imap/rest/services/Hydrology/MD_Floodplain/MapServer/exts/MDiMAPDataDownload/customLayers/1**

This dataset is flattened and multicounty communities are unsplit by county lines. Flattened means that there are no overlaps; larger shapes like counties are punched out or clipped where smaller communities are contained within them. This allows for choropleth shading and other mapping techniques such as calculating unincorporated county land area. Multicounty cities like Houston are a single feature, undivided by counties. This layer is derived from Census, State of Maine, and National Flood Hazard Layer political boundaries.rnrnThe Community Layer datasets contain geospatial community boundaries associated with Census and NFIP data. The dataset does not contain personal identifiable information (PII). The Community Layer can be used to tie Community ID numbers (CID) to jurisdiction, tribal, and special land use area boundaries.rnrnA geodatabase (GDB) link is Included in the Full Data section below. The compressed file contains a collection of files that can store, query, and manage both spatial and nonspatial data using software that can read such a file. It bcontains all of the community layers/b, not just the layer for which this dataset page describes. rnThis layer can also be accessed from the FEMA ArcGIS viewer online: https://fema.maps.arcgis.com/home/item.html?id=8dcf28fc5b97404bbd9d1bc6d3c9b3cfrnrnrnCitation: FEMA's citation requirements for datasets (API usage or file downloads) can be found on the OpenFEMA Terms and Conditions page, Citing Data section: https://www.fema.gov/about/openfema/terms-conditions.rnrnFor answers to Frequently Asked Questions (FAQs) about the OpenFEMA program, API, and publicly available datasets, please visit: https://www.fema.gov/about/openfema/faq.rnIf you have media inquiries about this dataset, please email the FEMA News Desk at FEMA-News-Desk@fema.dhs.gov or call (202) 646-3272. For inquiries about FEMA's data and Open Government program, please email the OpenFEMA team at OpenFEMA@fema.dhs.gov.

The Federal Flood Risk Management Standard (FFRMS) floodplain was developed by the Federal Emergency Management Agency (FEMA) to improve the resilience of communities and federal assets against the impacts of flooding. Through a series of Federal executive orders, the FFRMS was established (EOs 11988 and 13690); cancelled in 2017 (EO 13807); re-established in 2021 (EO 14030) and also mapped as the FFRMS floodplain; and then cancelled again in 2025 (EO 14148). This FFRMS floodplain data set was provided by FEMA at the request of Maryland Department of the Environment and is the same data available through the Flood Standard Support Tool (https://floodstandard.climate.gov/).3-meter DEM resolution terrain resolution used for this mapping. In some cases, 1-meter DEM data may have been re-sampled to a 3-meter DEM resolution. FEMA did this to create a consistent FFRMS data set nationwide. The primary sources of data used by FEMA to develop the FFRMS floodplain were USGS’s The National Map for terrain and FEMA’s National Flood Hazard Layer for regulatory water surface elevations.In Riverine areas, the FFRMS floodplain is derived from the National Flood Hazard Layer using the methodology developed by the Maryland Department of the Environment for production of the Riverine CRAB using a linear interpolation applied between two riverine cross sections from the National Flood Hazard Layer (FEMA 100-year floodplain). A freeboard (2-feet for the 2-foot freeboard map, and 3-feet for the 3-foot freeboard map) was added to the 100-year floodplain water surface elevation at each riverine cross section in the National Flood Hazard Layer data set. The new elevations were then interpolated to create a freeboard elevation gradient. This elevation gradient was used to map the horizontal extents of the FFRMS floodplain boundary based on topographic data. Additional details can be found here: https://www.fema.gov/sites/default/files/documents/fema_ffrms-data-methodology.pdfThe methodology to develop the coastal FFRMS floodplain (water surface) raster utilized the coastal static Base Flood Elevation values from the National Flood Hazard Layer as the water surface. To create an expanded surface, these water surface values were collected at uniformly spaced points along the boundary of the effective coastal 1%-annual-chance flood mapping and expanded inland utilizing Thiessen polygons. The Thiessen polygons were converted to a raster matching the spatial resolution of the terrain DEM, and the difference between the water surface elevation raster and the terrain was computed. Areas where the water surface raster value was higher than the terrain raster value indicate the area of flooding. Each freeboard value (2-foot and 3-foot) was mapped independently in whole foot increments utilizing the prior, lower freeboard value boundary of flooding to establish an expanded surface. One limitation of this methodology is that wave runup was modeled for the 100-year floodplain but not remodeled at the higher water surface elevation conditions.Please note that the CRAB data set shows inundation depths derived as the height difference between the DEM and the water surface elevation, whereas the FFRMS shows water surface elevations only. Their horizontal extents may be compared, but users should be careful comparing any color coding or depth values provided in the two applications.

This layer offers the anticipated floodplain boundaries however, the data shown are in the process of being reviewed and adopted by FEMA and a given community. Changes to the Preliminary boundaries may occur before official map adoption. Use this layer with caution. The effective regulatory floodplain should be used for conducting all official floodplain determinations until such time the preliminary floodplain is reviewed and adopted by FEMA and a given community. It is reasonable to assume that preliminary floodplain boundaries are more accurate than the Q3, but the Q3 may better represent the current regulatory Flood Insurance Rate Map (FIRM) when verified by using the paper FIRM.This is a MD iMAP hosted service. Find more information at https://imap.maryland.gov.Feature Service Link:https://mdgeodata.md.gov/imap/rest/services/Hydrology/MD_Floodplain/FeatureServer/0

This data contains City of Tucson mapped flood hazard areas. Circa 2007 - Shapefile created by consultant JE Fuller who was hired by the City to map non-FEMA flood hazards. It is a composite of the city's old Flood Hazard Zones and the new Flood Hazard Zones. Began by TDOT in the 70's and 80's, added to by Frank (some from JE Fuller study) to display areas that could flood but are too small to be looked at by FEMA.PurposeLorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.Dataset ClassificationLevel 0 - OpenKnown UsesThis layer is intended to be used in the City of Tucson's Open Data portal and not for regular use in ArcGIS Online, ArcGIS Enterprise or other web applications.Known ErrorsLorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.Data ContactLorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.Update FrequencyLorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.

FEMA is the author and publisher of this content. City of Las Cruces Enterprise GIS provides this content for informational purposes only. This view is filtered to only display flood hazard areas from the official FEMA 2016 flood certification file. Layer Type: PolygonData Owner: FEMAAuthoritative: YesDownloadable: YesInitial Dataset Creation: UnknownLast update: N/AUpdate Frequency: N/AReason for Update: City does not maintainFilters Applied: Flood hazard areasSource data: https://las-cruces.maps.arcgis.com/home/item.html?id=5f1906fd247244e8b1eef0212d0fa290Projected Coordinate System: N/ALimitations: OverviewThe National Flood Hazard Layer (NFHL) dataset represents the current effective flood data for the country, where maps have been modernized. It is a compilation of effective Flood Insurance Rate Map (FIRM) databases and Letters of Map Change (LOMCs). The NFHL is updated as studies go effective. For more information, visit FEMA's Map Service Center (MSC). You can view this information in a standalone viewer here: https://hazards-fema.maps.arcgis.com/apps/webappviewer/index.html?id=8b0adb51996444d4879338b5529aa9cdREST URL: https://hazards.fema.gov/gis/nfhl/rest/services/public/NFHL/MapServerBase Map ConsiderationsThe default base map is from an ESRI service and conforms to FEMA's specification for horizontal accuracy. This base map is composed of the orthoimagery used when the Flood Insurance Rate Maps (FIRMs) were initially created combined with standard imagery products managed by ESRI. This map should be considered the best online resource to use for official National Flood Insurance Program (NFIP) purposes when determining locations in relation to regulatory flood hazard information. If a different base map is used with the NFHL, the accuracy specification may not be met and the resulting map should be used for general reference only, and not official NFIP purposes.Further InformationFor more flood map data, tool, and viewing options, visit the FEMA NFHL page. National Flood Hazard Layer (NFHL) GIS Services Users GuideNational Flood Hazard Layer (NFHL): New Products and Services for FEMA's Flood Hazard Map Data

This map represents Flood Insurance Rate Map (FIRM) data important for floodplain management, mitigation, and insurance activities for the National Flood Insurance Program (NFIP). The National Flood Hazard Layer (NFHL) data present the flood risk information depicted on the FIRM in a digital format suitable for use in electronic mapping applications. The NFHL database is a subset of the information created for the Flood Insurance Studies (FIS) and serves as a means to archive a portion of the information collected during the FIS. The NFHL data incorporates Digital Flood Insurance Rate Map (DFIRM) databases published by Federal Emergency Management Agency (FEMA). The 100-year flood is referred to as the 1% annual exceedance probability flood, since it is a flood that has a 1% chance of being equaled or exceeded in any single year. 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 1% annual chance (base flood) is the flood that has a 1% chance of being equaled or exceeded in any year. The Special Flood Hazard area is the area subject to flooding by the 1% annual chance flood. Areas of Special Flood Hazard include Zones A, AE, AH, AO, AR, A99, D, V, VE, and X. These flood zones are explained below and reflects the severity or type of flooding in the area. A - Zone A is the flood insurance rate zone that corresponds to the 1-percent annual chance floodplains that are determined in the Flood Insurance Study by approximate methods of analysis. Because detailed hydraulic analyses are not performed for such areas, no Base Flood Elevations or depths are shown within this zone. Mandatory flood insurance purchase requirements apply. AE and A1-A30 - Zones AE and A1-A30 are the flood insurance rate zones that correspond to the 1-percent annual chance floodplains that are determined in the Flood Insurance Study by detailed methods of analysis. In most instances, Base Flood Elevations derived from the detailed hydraulic analyses are shown at selected intervals within this zone. Mandatory flood insurance purchase requirements apply. AH - Zone AH is the flood insurance rate zone that corresponds to the areas of 1-percent annual chance shallow flooding with a constant water-surface elevation (usually areas of ponding) where average depths are between 1 and 3 feet. The Base Flood Elevations derived from the detailed hydraulic analyses are shown at selected intervals within this zone. Mandatory flood insurance purchase requirements apply. AO - Zone AO is the flood insurance rate zone that corresponds to the areas of 1-percent shallow flooding (usually sheet flow on sloping terrain) where average depths are between 1 and 3 feet. Average flood depths derived from the detailed hydraulic analyses are shown within this zone. In addition, alluvial fan flood hazards are shown as Zone AO on the Flood Insurance Rate Map. Mandatory flood insurance purchase requirements apply. AR - Zone AR is the flood insurance rate zone used to depict areas protected from flood hazards by flood control structures, such as a levee, that are being restored. FEMA will consider using the Zone AR designation for a community if the flood protection system has been deemed restorable by a Federal agency in consultation with a local project sponsor; a minimum level of flood protection is still provided to the community by the system; and restoration of the flood protection system is scheduled to begin within a designated time period and in accordance with a progress plan negotiated between the community and FEMA. Mandatory purchase requirements for flood insurance will apply in Zone AR, but the rate will not exceed the rate for an unnumbered Zone A if the structure is built in compliance with Zone AR floodplain management regulations. A99 - Zone A99 is the flood insurance rate zone that corresponds to areas within the 1-percent annual chance floodplain that will be protected by a Federal flood protection system where construction has reached specified statutory milestones. No Base Flood Elevations or depths are shown within this zone. Mandatory flood insurance purchase requirements apply. D - Zone D designation is used for areas where there are possible but undetermined flood hazards. In areas designated as Zone D, no analysis of flood hazards has been conducted. Mandatory flood insurance purchase requirements do not apply, but coverage is available. The flood insurance rates for properties in Zone D are commensurate with the uncertainty of the flood risk. V - Zone V is the flood insurance rate zone that corresponds to areas within the 1-percent annual chance coastal floodplains that have additional hazards associated with storm waves. Because approximate hydraulic analyses are performed for such areas, no Base Flood Elevations are shown within this zone. Mandatory flood insurance purchase requirements apply. VE - Zone VE is the flood insurance rate zone that corresponds to areas within the 1-percent annual chance coastal floodplain that have additional hazards associated with storm waves. Base Flood Elevations derived from the detailed hydraulic analyses are shown at selected intervals within this zone. Mandatory flood insurance purchase requirements apply. X - Zone X is the flood insurance rate zones that correspond to areas outside the 1-percent annual chance floodplain – Areas protected from the 1-percent annual chance flood by levees. No Base Flood Elevations or depths are shown within this zone. Insurance purchase is not required in these zones. More information about the flood zones can be found here. The NFHL data are derived from Flood Insurance Studies (FISs), previously published Flood Insurance Rate Maps, flood hazard analyses performed in support of the FISs and FIRMs, and new mapping data where available. The NFHL data is available at State level. The data is updated on monthly basis and FEMA is in the process of mapping all the flood zones and so some counties do not have complete data. For better visualization, it’s recommended to display the service with 50% transparency. The map service has a county layer that helps differentiate between the counties that have flood data available and those that do not. The flood data is scale dependent and is set to show from 1:3,000,000. This data is as of March 2011.

The Federal Flood Risk Management Standard (FFRMS) floodplain was developed by the Federal Emergency Management Agency (FEMA) to improve the resilience of communities and federal assets against the impacts of flooding. Through a series of Federal executive orders, the FFRMS was established (EOs 11988 and 13690); cancelled in 2017 (EO 13807); re-established in 2021 (EO 14030) and also mapped as the FFRMS floodplain; and then cancelled again in 2025 (EO 14148). This FFRMS floodplain data set was provided by FEMA at the request of Maryland Department of the Environment and is the same data available through the Flood Standard Support Tool (https://floodstandard.climate.gov/).3-meter DEM resolution terrain resolution used for this mapping. In some cases, 1-meter DEM data may have been re-sampled to a 3-meter DEM resolution. FEMA did this to create a consistent FFRMS data set nationwide. The primary sources of data used by FEMA to develop the FFRMS floodplain were USGS’s The National Map for terrain and FEMA’s National Flood Hazard Layer for regulatory water surface elevations.In Riverine areas, the FFRMS floodplain is derived from the National Flood Hazard Layer using the methodology developed by the Maryland Department of the Environment for production of the Riverine CRAB using a linear interpolation applied between two riverine cross sections from the National Flood Hazard Layer (FEMA 100-year floodplain). A freeboard (2-feet for the 2-foot freeboard map, and 3-feet for the 3-foot freeboard map) was added to the 100-year floodplain water surface elevation at each riverine cross section in the National Flood Hazard Layer data set. The new elevations were then interpolated to create a freeboard elevation gradient. This elevation gradient was used to map the horizontal extents of the FFRMS floodplain boundary based on topographic data. Additional details can be found here: https://www.fema.gov/sites/default/files/documents/fema_ffrms-data-methodology.pdfThe methodology to develop the coastal FFRMS floodplain (water surface) raster utilized the coastal static Base Flood Elevation values from the National Flood Hazard Layer as the water surface. To create an expanded surface, these water surface values were collected at uniformly spaced points along the boundary of the effective coastal 1%-annual-chance flood mapping and expanded inland utilizing Thiessen polygons. The Thiessen polygons were converted to a raster matching the spatial resolution of the terrain DEM, and the difference between the water surface elevation raster and the terrain was computed. Areas where the water surface raster value was higher than the terrain raster value indicate the area of flooding. Each freeboard value (2-foot and 3-foot) was mapped independently in whole foot increments utilizing the prior, lower freeboard value boundary of flooding to establish an expanded surface. One limitation of this methodology is that wave runup was modeled for the 100-year floodplain but not remodeled at the higher water surface elevation conditions.Please note that the CRAB data set shows inundation depths derived as the height difference between the DEM and the water surface elevation, whereas the FFRMS shows water surface elevations only. Their horizontal extents may be compared, but users should be careful comparing any color coding or depth values provided in the two applications.