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Digital Flood Insurance Rate Maps

The Federal Emergency Management Agency (FEMA) issues Digital Flood Insurance Rate Maps (DFIRMs) and Flood Insurance Studies (FIS) for communities participating in the National Flood Insurance Program (NFIP).  This website provides access to the DFIRM data for the cities of Tucson and South Tucson and the towns of Marana, Oro Valley and Sahuarita, as well as unincorporated areas of Pima County.  Geographic Information System (GIS) map applications on this website enable users to view floodplain boundaries and other relevant information, as well as Letters of Map Revision (LOMRs) and Letters of Map Amendment (LOMAs). This data is used by lenders to determine if a structure is within a Special Flood Hazard Area (SFHA) for flood insurance requirement purposes. 

Please Note:  The DFIRMs are published by FEMA and do not show flood hazards mapped by local jurisdictions.

Questions and Answers about DFIRMs

What are FIRMS and DFIRMs?

The acronym FIRM stands for Flood Insurance Rate Map.  DFIRMS are digital versions of the FIRM. Since the data is digitally created it can more easily and accurately used in a Geographic Information System (GIS) map application to provide public access to detailed information regarding flood hazards.

The individual DFIRM maps, called panels, are what lenders use to determine if a structure is in a Special Flood Hazard Area (SFHA). They are used to determine whether flood insurance is required, and how much flood insurance coverage will cost.

The current effective FIRMs are the L Series DFIRMs, which became effective on June 16, 2011, though a number of panels in the Agua Caliente Wash area have since been replaced and are M Series DFIRMs. All of the previous K Series FIRMs have been superseded and should not be used for anything but historical comparison.

What is the 100-year floodplain?

The DFIRMs primarily show what is often called the 100-year flood, a misleading term for a flood that has a 1 (one) percent chance of occurring during any given year. A more appropriate term is the 1-percent chance flood, also known as the base flood, because the "100-year" flood can occur two years in a row, or even twice in the same year. FEMA calls areas subject to the 1-percent chance flood "Special Flood Hazard Areas" (SFHA). Be aware the DFIRMs do not show all the “100-year” floodplains in Pima County.  Contact your Local Floodplain Jurisdiction for additional floodplain information in your area.

FEMA designates different types of floodplains with different identifiers. Please see the FEMA Flood Hazard Zone Definitions page for more information.

What does it mean if my property has been removed from the FEMA mapped 100-year floodplain with the L Series DFIRMs?  Is flooding still a possibility?

Being outside of a Special Flood Hazard Area on a FIRM panel is NOT a guarantee that your house or property will not flood.

To begin with, the DFIRMs do not show all areas subject to the 1 percent chance ("100-year") flood. The DFIRMs only reflect major floodplains. Some properties are adversely impacted by tributary flow or by local drainage not reflected on the federal maps. Your local jurisdiction likely has mapped flood hazards that FEMA does not show on the DFIRMs. Subdivision plats may also contain flood and erosion hazard information, either on the maps or in the plat notes.

It is also very important to realize that the floodplain delineations on the DFIRMs are lines on a map and, just as floods don't look at calendars to know when to occur (see "What is the 100-year floodplain?"), floods also don't read maps. While FEMA uses the best available data in creating the maps, variations in the intensity or duration of rainfall, small variations in ground topography, and other factors can have significant impacts on whether a house near the mapped floodplain boundary will be safe from flooding or not.

In addition, storms do occur that have intensities greater than the 1-percent chance event. In addition, changes in river or watershed characteristics could increase flood depths and discharges. The Shaded Zone X designation may also represent areas of shallow flooding (less than one foot) during a 1-percent chance event.

Just because your house or business is outside of the mapped floodplain does not mean your house will not flood, even during the base flood that FEMA and local jurisdictions regulate to, let alone during the larger flood events that they do not regulate to.

For these reasons, the District recommends flood insurance for all properties in or near floodprone areas. For those properties outside of the SFHA, flood insurance is inexpensive, and while it is a bit more expensive in SFHAs, flood insurance is invaluable if disaster strikes.

It is important to realize that your homeowners or renters insurance will NOT cover your property or belongings in the event of a flood.

What do the Floodplain Change Areas layers mean in the MapGuide application?

The MapGuide application contains a layer called Flood Hazard Zone Difference Areas and a layer called Floodplain Change Areas. The Flood Hazard Zone Difference Areas layer shows the locations where there is any kind of difference between the effective L Series DFIRMs and the previous K Series FIRMs. The Floodplain Change Areas layer shows not only the locations where there is any kind of difference between the current effective DFIRMs and the previous FIRMs, but also describes what type of change occurred. Below is an explanation of terminology used in the Floodplain Change Areas layer.
  • ADDED-SFHA - Areas shown in red are areas that are within a Special Flood Hazard Area (SFHA) on the DFIRM that were not in an SFHA on the previous FIRM. This includes areas of new mapping and areas where the floodplain boundary has expanded.
  • CHANGE-NONSFHA - Areas shown in light green are areas in which there has been a change from one non-SFHA zone to a different non-SFHA zone, for example a change from Zone X (Shaded) to Zone X (unshaded).
  • CHANGE-SFHA - Areas shown in blue are areas in which there has been a change from one SFHA zone to a different SFHA zone, for example a change from Zone A to Zone AO1
  • REMOVED-SFHA - Areas shown in green are areas in which there has been a change from an SFHA zone to a non-SFHA zone, for example a change from Zone AE to Zone Shaded X. It is important to note that while a change of this type may remove the federal insurance requirement, the resulting floodplain may still be regulatory according to the local jurisdiction, and you should check with your jurisdiction to determine whether any restrictions to development exist.

What if I think there are errors in the maps?

The old K Series FIRMs and new, effective L Series DFIRMs were/are generated by FEMA, which bears ultimate responsibility for all of the content of the FIRMs and DFIRMs. While the District is interested in knowing about any errors found on the DFIRMs, all requests for corrections or changes must have been submitted to FEMA. The appeal and protest period for the latest FIRM revisions has passed, therefore further correction to the DFIRMs must be made through the Letter of Map Revision (LOMR) process. For more information on LOMRs, please visit FEMAs LOMR web page.

Who do I contact for more information?

While FEMA is solely responsible for creating the DFIRMs, various local jurisdictions are charged with administering the maps and enforcing FEMA regulations. The local jurisdictions within Pima County are: City of Tucson, Town of Marana, Town of Oro Valley, Town of Sahuarita, and the Pima County Regional Flood Control District (for unincorporated portions of Pima County not administered by the other jurisdictions). If you have questions regarding the DFIRMs or flood hazards that aren't answered by the information presented here and that is not available from the maps and other information available below, please contact your Local Floodplain Jurisdiction. The Pima County Regional Flood Control District may not be able to fully assist residents of other jurisdictions.

Flood Insurance

Although the Flood Disaster Protection Act of 1973 requires only federally insured lenders to obtain flood insurance on loans for structures within a federally mapped Special Flood Hazard Area (SFHA) floodplain, all property owners are encouraged to use this website to determine whether floodplains impact them.

Visit FloodSmart.gov or talk to an insurance agent to obtain flood insurance premium estimates for your property. You may also wish to read the FEMA Frequently Asked Questions sheet on how revised flood hazards effect existing structures.  For more information on flood insurance, please see the Relevant Links tab this page.

Flood Hazards Mapped by Local Jurisdictions

It is important to note that the DFIRMs do NOT show flood or erosion hazard areas that are mapped by local jurisdictions. If your property is not in a FEMA floodplain as shown on the FIRMS, it may be in a floodplain or erosion hazard area that has been identified by a local jurisdiction.  Subdivision plats may also show mapped flood and/or erosion hazards. Please contact your local jurisdiction to determine your local floodplain status. Within unincorporated Pima County, you may view a Flood Hazard Map which shows all floodplains currently mapped by FEMA and by the District. This map does not show erosion hazard areas, and is not a guarantee that your property isn't subject to flood and/or erosion hazards since there are areas subject to flood hazards that have not yet been identified and mapped by the District. This map also does not show floodplain or erosion hazards that are shown on some subdivision plats. For properties within a subdivision, please review the plat notes and the map pages for flood and erosion hazard information.

Viewing DFIRMs

In order to provide the greatest level of accessibility to the public, the District has created this website, which includes a parcel search application.  The website also includes links to FEMA map change documents. Hardcopies are available through each local jurisdiction, which is the local map repository for flood maps in that jurisdiction (i.e. City of Tucson, Town of Marana, Unincorporated Pima County, etc.)
  • FIRM Panel Review Parcel Information. The search function below will take you to a page that contains your parcel information and provides the following information:
    • FEMA Flood Hazard Area. Please note that these results are for the entire property, while insurance requirements are based on the flood hazard zone(s) impacting the insurable structure(s) on the property. It is possible for a property to be partially in a floodplain while the structure is outside of the floodplain. Only a review of the maps can be used to determine if your structure is in the floodplain or not.
    • DFIRM panel number, which includes a link to the official FEMA PDF of the L Series and newer DFIRM panels.
    • Link to a MapGuide map, zoomed to your parcel, showing the floodplain mapping.
  • Digital PDF files. NOTE: These files are reachable through the search function above, the use of which is recommended if you don't know which DFIRM Panel your property is on.
  • Floodplain MapGuide Maps. Read the Disclaimer and Using Autodesk MapGuide.  The District has created two Floodplain MapGuide maps for public use.
    • The Unincorporated Pima County Floodplain map shows FEMA and locally mapped floodplains for unincorporated Pima County, but does not show any floodplains for other jurisdictions.
    • The Pima County FEMA Floodplain map shows FEMA floodplains for the entire county but does not show any floodplains mapped by local jurisdictions. (NOTE: This map has been updated to the new PimaMaps viewer. The MapGuide viewer is no longer being supported.)

    If you have trouble viewing the map using the MapGuide viewer, please use PDF files or the search functions above. If using one of the search functions, choose the "Parcel Info." button after doing the parcel search.   From the Parcel Information page, click on the "Flood Insurance Rate Map" link about 1/3 down the page and locate your property visually on the PDF version of the DFIRM.

    For best viewing maximize your browser window to fill your screen. If you have a little screen space to spare, you may want to expand the legend by dragging the right legend edge to make it easier to see the layer names. You can always see full legend layer names by hovering the mouse cursor over the names.

    To have the yellow map tip information display FEMA flood hazard zone information instead of showing parcel information when the mouse is hovered over the map, turn the parcel layer off using the checkbox in the legend or the checkbox above the map window.

    FEMA designates different types of floodplains with different identifiers. Please see the FEMA Flood Hazard Zone Definitions page for more information.

    Aerial photo coverage - The DFIRMs utilize a mixture of three different aerial photo coverages. Most of eastern Pima County is covered by 2002 aerial photographs which was the most up to date coverage when the map update process was started. Most of the rest of Pima County is covered by 2006 aerial photographs, except for areas around the Town of Ajo, which utilize 2005 aerial photographs. These layers must be turned on in the MapGuide map.  Other aerial photography layers are also available and more recent aerial photography may be useful in areas that are recently developed. However, it is important to note that the aerial photographs noted above are what are used on the official L Series DFIRMs and are therefore the regulatory standard.

List of Acronyms and Definitions

  • BFE - Base flood elevation or the water surface elevation contour line
  • DFIRM - Digital Flood Insurance Rate Map
  • FEMA - Federal Emergency Management Agency
  • FIRM - Flood Insurance Rate Map
  • FIS - Flood Insurance Study
  • LFD – Letter of Final Determination
  • LOMA - Letter of Map Amendment
  • LOMC - Letter of Map Change
  • LOMR - Letter of Map Revision
  • LOMR-F - Letter of Map Revision based on fill
  • NAVD88- North American Vertical Datum of 1988
  • NFIP - National Flood Insurance Program
  • NGVD29- National Geodetic Vertical Datum of 1929
  • NONSFHA - Not a Special Flood Hazard Area (NONSFHA includes FIRM Zones D, X and X (shaded))
  • PAL - Provisionally Accredited Levee
  • PDFIRM - Preliminary Digital Flood Insurance Rate Map
  • SFHA - Special Flood Hazard Area (FIRM Zones A, AE, AH, and AO)

Related Documents for DFIRMs and the 2011 FIRM Revision

Flood Insurance Study (FIS)

For floodway data tables, floodway profiles and other supporting data, please see the complete FEMA Flood Insurance Study (FIS).

Letters of Final Determinations (LDFs) and Letters of Map Changes (LOMC)

In the time between when the old K Series FIRMs were published in February of 1999 and the new L Series DFIRMs were published on June 16, 2011, there were over 1,000 modifications made to the floodplain information in the form of Letters of Map Amendment (LOMA) or Letters of Map Revision (LOMR).  Some of these LOMAs and LOMRs were incorporated into the DFIRMs and others were not. Letter of Final Determinations (LFDs) Letters of Map Changes (LOMCs) are used to identify which map changes were incorporated into the DFIRMs and which were not.  The links below are to the LFD and LOMC data for each floodplain jurisdiction in Pima County.

LFDs and LOMCs for Pima County Jurisdictions

Comments from Local Jurisdictions and FEMA Response Summary letters

A number of local jurisdictions provided comments to FEMA regarding errors and deficiencies with the Preliminary DFIRMs before they became effective. The District provided FEMA with comments outlining corrections that the District felt needed to be made to the FIRM panels. Comments from local jurisdictions are available for review below:

 

Understanding Vertical Datums and Elevations on DFIRMs

All Flood Insurance Studies (FIS) and FIRMs are referenced to a specific vertical datum.  The vertical datum provides a starting point against which flood, ground, and structure elevations can be referenced and compared.  The standard datum for the old K Series FIRMs was the National Geodetic Vertical Datum of 1929 (NGVD29).

All flood elevations shown in the "L" series and newer Flood Insurance Study (FIS) report and on the FIRM panels are referenced to the North American Vertical Datum of 1988 (NAVD88).  Structure and ground elevations in the community must, therefore, be referenced to NAVD88. At any specific location, the NAVD88 elevation can be 1.72 to 2.39 feet higher than the old NGVD29 elevation.  This does not mean that the ground surface or water surface elevation has physically changed, it just means that the baseline (mean sea level) has changed. 

For more information on NAVD 88, see "Converting the National Flood Insurance Program to the North American Vertical Datum of 1988", FEMA Publication FIA-20/June 1992, contact the Vertical Network Branch, National Geodetic Survey, Coast and Geodetic Survey, National Oceanic and Atmospheric Administration, Rockville, Maryland 20910, or talk with a surveyor.

Relevant Links

For FEMA Letters of Final Determination, Letters of Map Change, and Map Errors and Corrections from the map update process, including comments provided to FEMA from local jurisdictions, please see Related Documents tab above.