County Data and Map Viewers

The following counties have data and/or viewers available, in addition to the official FEMA maps on FEMA's Maps Service Center (link is external).

Pending New FEMA Maps

FEMA maps move from preliminary to pending six month prior to becoming effective. These maps are available on FEMA's interactive Flood Map Changes Viewer. Once a map is effective, it will be on FEMA's Map Service Center and not on the Flood Map Changes Viewer.

Preliminary New FEMA Maps

Preliminary new FEMA maps show the latest data. These maps are not official for insurance determinations.

  • A Zone data can be used as "best available data" for local permit decisions or for FEMA map appeals and amendments.
  • Zones AE, A1-30, AO and AH data on current effective maps continue to be official until new effective maps are issued. If preliminary new map data are more restrictive, communities are strongly encouraged to use the more restrictive data.

County Work Maps

An interactive map to see floodplain data that is not on official effective maps (which would be used for flood insurance determinations), but that can often be used as "best available data" for local permit decisions or for FEMA map appeals and amendments.

Changes Since Last Flood (CSLF) Insurance Rate Map Viewers

Interactive map comparing the floodway and floodplain area on current effective maps versus what is mapped on new county work maps or preliminary new maps. The CSLF shows areas newly identified at high risk, areas previously mapped that continue to be identified at high risk, and areas currently shown at high risk that are not at high risk based on more accurate data.

Depth Grid Maps

Depth Grid Maps show the depth of flooding for a specific storm event, usually the 1percent chance (or 100-year) storm event. The depth grids can help better understand flood risk (such as, the deeper the flooding, the higher the risk if flooded). The depth grids can also help communities determine flood mitigation options, like homes in deeper areas could be considered for buy-out, while homes in shallow areas could be flood proofed.

Percent-Annual-Chance Maps

The Percent-Annual-Chance Map shows the percent chance of flooding during any given year. For example, a structure at the edge of the "100-year floodplain" has a 1 percent chance of flooding during any given year. Structures outside the 100-year floodplain may not be in the "regulatory" floodplain and may not be required to buy flood insurance, but they still have a 0.2 percent chance of flooding during any given year. These maps help residents understand that their level of risk isn't captured by looking only at the Flood Insurance Rate Map.

County Supported Map Viewers

Many counties have floodplain data shown in interactive maps on county sites. Each county shows the floodplain data in a different manner, but they typically allow lot lines and other county data to be viewed or viewed with links.