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Indiana Department of Natural Resources

Water > Surface Water > Hydrologic / Hydraulic Models & Assessments > Indiana Floodplain Mapping > Indiana Floodplain Mapping FAQs Indiana Floodplain Mapping FAQs

Frequently Asked Questions

Q. What is the Indiana Floodplain Mapping Initiative?

A. The partnership will develop updated Flood Insurance Rate Maps (FIRMs) for 83 of the 92 counties in the state. FEMA will complete the remaining nine counties. The new digital floodplain mapping will be based on updated topographic and orthographic data, and in some cases, revised hydrologic and hydraulic analysis. Preliminary county maps will be posted on the DNR website ( for review and comment before final maps are submitted to FEMA for adoption

Q. What is a Base Flood Elevation (BFE)?

A. A Base Flood Elevation (BFE) is the elevation the floodwaters will reach during the 1 percent annual chance flood.

Q. What is the 1 % Annual Chance Flood?

A. The 1 percent annual chance flood (also known as the 100-Year Frequency Flood or Base Flood) is the flood that has a 1 percent chance of being equaled or exceeded in any given year. Any flood zone that begins with the letter A is subject to the 1 percent annual chance flood.

Q. I have flood insurance and my house is in an A Zone according to the current flood map. The new flood map, however, will show my house as being in a low-risk flood zone (B, C, or X-zone). Will I have to continue to carry flood insurance when the new map takes effect?

A. If you have Federal or federally related financing for your home, you will no longer have a Federal requirement to purchase flood insurance when the new flood map takes effect. However, lenders still have the right to require flood insurance, even for buildings no longer in an A Zone. If you want to continue coverage after the new maps take effect, you may be eligible for much lower rates based on your home being outside the A Zone. You should have your policy re-rated using the new maps, which should lower your premium. Even if you are not required to purchase flood insurance, homeowners are encouraged to continue coverage at the lower rates in the event you are flooded by an event greater than the 1% annual chance flood.

Q. My house is not in an A Zone according to the current flood map, but the new map will show it as being an A Zone. Will I have to purchase flood insurance when the new map officially takes effect?

A. Yes, if you have Federal or federally related financing for your home and you do not already have flood insurance. Your lender will contact you once the new map takes effect and require you to purchase flood insurance. If you do not purchase the insurance within 45 days after being notified, the lender can purchase the insurance for you at a higher premium and charge you for the cost. If you dispute the determination that your home is located in an A Zone, you and your lender can jointly request a Letter of Determination Review from FEMA at a cost of $80. The review request must be submitted within 45 days of notification that your home is located in an A Zone. If you have insurance before the new maps take effect, the basis for rating that policy is unchanged.

Q. Will I be notified of a change in floodplain status for my property?

A. Once preliminary mapping is produced for a particular county, notification will be sent to affected property owners advising them of a flood zone status change and informing them of a scheduled open house where they may look at the new maps and get answers to various questions they may have.

Q. How does a preliminary map become effective?

A. After the open house, there is a 90-day appeal period to challenge the preliminary mapping. Updated maps become final six months after all disputes have been resolved.

Q. What if a person disagrees with the new flood zone for a piece of property?

A. There are two options:

  • Appeal Process
    The appeal is a formal objection to new or revised Base Flood Elevations (BFEs) shown on a Preliminary Digital Flood Insurance Rate Map (DFIRM) or Flood Insurance Survey (FIS) report. Predicted flood elevations can be appealed if they are shown to be scientifically or technically incorrect. The distinction between "scientifically incorrect" and "technically incorrect" is important because of the differences in the types and amounts of data needed in support of an Appeal Petition.

    A study that determines BFEs along a stream involves collection of historical and physical data, followed by analyses to determine flow rates and water-surface elevations. Various information is required to support an appeal, depending on the part of the study being challenged.

  • Protest Process
    A formal objection to any new or revised information shown on a Preliminary DFIRM or FIS report submitted during the 90-day appeal period that does not involve BFEs is considered a protest. Protests generally involve comments regarding the delineation of the updated floodplain and/or floodway boundaries, corporate limits, road names, and road locations.

  • Resolution of Appeal and Protest Petitions
    The Indiana DNR will send an Acknowledgement Letter notifying the community that an Appeal or Protest has been received. The supporting data will be reviewed to determine if it constitutes a valid Appeal or Protest and if the formal petition supports a revision. After reviewing all submitted data, an Appeal Resolution Letter will be sent to the community explaining the resolution of the Appeal or Protest. A revised Preliminary Transmittal Letter, including a revised Preliminary FIS report and/or DFIRM that incorporates changes made, as a result of the Appeal or Protest, will be sent to the community, if necessary. The community has 30 days to review and comment on the resolution when necessary. At the end of the comment period and after all resolutions are completed, FEMA issues a Letter of Final Determination to the impacted community, publishes the new or revised BFEs in the Federal Register, and initiates the final production of the FIS report and DFIRM.

Q. How can I find out when new maps will become available for my community? How can I get more information?

A. Visit the Indiana Department of Natural Resources, Division of Water's website at:

Or contact us at:

Indiana Department of Natural Resources
Division of Water
402 W. Washington Street, Room W264
Indianapolis, IN 46204
877-928-3755 (Toll Free)

Indiana Floodplain Mapping Quick Links

FAQFrequently Asked Questions:  Answers regarding floodplain maps and flood insurance.

Prelim MapsPreliminary Digital Flood Insurance Rate Maps:  View and download preliminary Digital Flood Insurance Rate Maps issued by FEMA and IDNR.  If you received a letter from IDNR regarding changes to the floodplain status of a property, click here to view maps.

General guidelinesGeneral Guidelines for the Hydrologic-Hydraulic Assessment of Floodplains in Indiana:  Technical guidance documents for developing floodplain modeling.  Also includes external links to other modeling information.

Floodplain managementFloodplain Management: More information regarding floodplain management with respect to both insurance and construction.

Floodplain PortalIndiana Floodplain Information Portal:  Launch INFIP, an interactive floodplain mapping tool, which includes address searching and eFARA, the Division of Water’s on-line floodplain analysis submittal program.  If you received a letter from IDNR regarding changes to the floodplain status of a property, click here to enter an address and view floodplain information.

Indiana Peak Discharge Determination SystemIndiana Peak Discharge Determination System:  Launch IPDDS, the Division of Water’s hydrologic computation system.  Includes directions on how to submit information to the Division for approval (under construction). 

The Indiana Hydrology and Hydraulics Model LibraryNEW! The Indiana Hydrology and Hydraulics Model Library: View and download previous hydrologic and hydraulic models developed for Flood Insurance Studies, Construction in a Floodway applications, Floodplain Analysis / Regulatory Assessment (FARA), others.

ContactESC Contact Information:  Contact information for the ESC section managers.

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