Profile Baselines

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 labels River Miles Markers Cross-sections and coastal transects and their labels Letter of Map Revision (LOMR) boundaries and case numbers Flood Insurance Rate Map (FIRM) boundaries, labels and effective dates Coastal Barrier Resources System (CBRS) and Otherwise Protected Area (OPA) units Community boundaries and names Levees Hydraulic and flood control structures Profile and coastal transect baselines Limit 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 Layers The 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 Data Preliminary 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 GeoPlatform FEMA'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 Information Flood 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 & Display The 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 Availability 1. LOMRs 2. LOMAs 3. FIRM Panels 4. Base Index 5. PLSS 6. Toplogical Low Confidence Areas 7. River Mile Markers 8. Datum Conversion Points 9. Coastal Gages 10. Gages 11. Nodes 12. High Water Marks 13. Station Start Points 14. Cross-Sections 15. Coastal Transects 16. Base Flood Elevations 17. Profile Baselines 18. Transect Baselines 19. Limit of Moderate Wave Action 20. Water Lines 21. Coastal Barrier Resources System Area 22. Political Jurisdictions 23. Levees 24. General Structures 25. Primary Frontal Dunes 26. Hydrologic Reaches 27. Flood Hazard Boundaries 28. Flood Hazard Zones 29. Submittal Information 30. Alluvial Fans 31. Subbasins 32. Water Areas