Floodplains_Content Page_Mapping

Floodplain Mapping

The Federal Emergency Management Agency (FEMA) produces Flood Insurance Rate Maps (FIRMs) that show areas at risk of flooding. The FIRMs are based on engineering studies called Flood Insurance Studies (FIS). The FIRMs can be changed through Letters of Maps Change (LOMCs).

Using the maps

FIRMs are maps of areas at risk to flooding also known as floodplains or Special Flood Hazard Areas (SFHAs). Effective FIRMs and Preliminary FIRMs are available on FEMA's Map Service Center. To learn more about using the maps visit FEMA's FIRM or FIS Tutorials. FEMA also provides several interactive map viewers that display the digital flood hazard data used to create the FIRMs.

Mapping process

In the past, FIRMs were produced by FEMA and distributed on paper. In 2003, FEMA implemented a map modernization initiative to upgrade and distribute the maps in a digital format rather than on paper. Now maps are developed through FEMA’s Risk Mapping, Assessment and Planning (RiskMAP) process. All RiskMAP projects are based on the best available data using the latest technologies including Light Detection and Ranging (LiDAR) elevation data used to map floodplains.

The spatial data displayed on the FIRMs is incorporated into FEMA's National Flood Hazard Layer (NFHL) which can be viewed on DNR's mapping application. In addition, engineering input models and flood insurance study text can be downloaded within the mapping application by identifying a reach in the Analysis Lines layer.

Risk MAP

Risk MAP is a FEMA-led process, facilitated by the Wisconsin DNR and used to update or create FIRMs. The FIRMs and other datasets created during this process are used to help move communities toward flood resilience. Flood risk datasets work alongside regulatory products (FIRMs and the FIS) to provide flood risk information and support the community's floodplain management and hazard mitigation strategies. To see a list of current Risk MAP Projects, visit the Risk MAP Projects webpage.

Mapping steps

There are several key meetings and milestones that occur throughout the RiskMAP project lifecycle, which are listed below. To learn more about each of these steps please visit FEMA's Lifecycle of a Risk Map Project webpage.

  • Discovery: FEMA and the Risk MAP project team meet with representatives from the communities to gather information on local flood risk priorities and any available data.
  • Project Kickoff Meeting: The Risk MAP project team may hold this meeting to introduce communities to project specifics and scope of work prior to data development.
  • Data Development: If a study is funded, hydrologic and hydraulic modeling is completed and the latest LiDAR topographic data is acquired for mapping.
  • Flood Risk Review (FRR) and Resilience Meetings: When data development is finished, draft flood hazard data is presented to the communities for review and any non-regulatory products (flood depth and analysis girds, changes since last FIRM, areas of mitigation interest) that were created are also made available.
  • Preliminary Flood Map Release: Once preliminary products (FIRMs and the FIS) have been released, they can be viewed at FEMA's Map Service Center by selecting the appropriate county and community from the jurisdiction menu.
  • Consultation Coordination Officer (CCO) Meeting and Public Open House: : After preliminary release, the CCO meeting presents the new mapping to local officials, followed by an open house for the public to view the changes.
  • 90-Day Comment and Appeal Period : Following two public notices in a local newspaper, this 90-day period allows the opportunity for comments and appeals to be submitted on the updated maps. Appeals must meet standard requirements, and any submissions should be routed through community zoning administrators prior to review.
  • The Letter of Final Determination (LFD) and effective date are the final milestones in a flood risk project. FEMA sends the LFD letter to the community’s chief executive officer stating that the final notice of flood hazard determinations will be published in the Federal Register and the new or updated FIRMs and FIS will soon reach effective status. The receipt of this letter starts the 6-month adoption phase of the process. This is where communities need to update their floodplain ordinances to incorporate the updated FIRMs and FIS, by the federal effective date, to remain in good standing in the National Flood Insurance Program (NFIP). Currently, most communities also update their floodplain zoning ordinance language so that the current regulations meet state and federal minimum standards. DNR floodplain staff can set up a draft floodplain zoning ordinance for the community to review. This assistance is provided by the DNR, to communities, free of charge. If you are interested, please email DNRFloodplain@Wisconsin.gov.

This graphic outlines the mapping process and provides an approximate timeline of a Risk MAP project from start to end.