History
Learn more about the history of flooding and floodplain management in Wisconsin
Mapping
Discover how floodplains are mapped in Wisconsin
Ordinances
Find out what regulations apply in floodplains and how to adopt an ordinance
Insurance
Learn more about the National Flood Insurance Program
Contact Information
Chris Olds
Floodplain Engineer
Dam Safety and Floodplain
608-266-5606
Gary Heinrichs
Floodplain Planning Program Manager
Dam Safety and Floodplain
608-266-3093

Mapping

The Federal Emergency Management Agency (FEMA) produces Flood Insurance Rate Maps (FIRMs) that show areas at risk to 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

Flood Insurance Rate Maps (FIRMs) are maps of areas at risk to flooding also known as floodplains or Special Flood Hazard Areas (SFHA). Newer FIRMs use aerial photos as the base layer making it easier to determine if a structure or property is within a mapped floodplain. FIRMs can be viewed on FEMA’s Map Service Center [exit DNR] or on the department’s mapping site. A tutorial for reading FIRMs can be viewed at FIRM Tutorial [exit DNR]. Other mapping related tutorials such as the Flood Insurance Study Tutorial are available at FEMA [exit DNR].

Mapping process

In the past, Flood Insurance Rate Maps 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. The newer maps are called Digital Flood Insurance Rate Maps (DFIRMs). The DFIRMs show areas at risk to flooding overlain on aerial photos. In addition, the best available terrain data [PDF] were used in the mapping process, which results in higher quality mapping products.

DFIRMs are displayed on our interactive mapping application, where available. Where DFIRMs are not yet available, we have scanned the effective paper FIRMs and geo-registered them. All of this information can be overlayed on top of aerial photos or U.S. Geological Service topographic map images. In addition, engineering input models and flood insurance study text can be downloaded by identifying a reach in the Analysis Lines layer.

Risk MAP

In 2010, FEMA implemented Risk MAP (Mapping, Assessment and Planning), the next phase in floodplain mapping now that the map modernization phase is complete. Risk MAP is: A new multi-year FEMA program using a watershed approach (vs. the countywide approach used previously).

Wisconsin counties project status

View a table showing the Wisconsin counties project status [PDF].

Back to Top

Mapping steps

The creation of new flood maps is a multi-step process.

  • Step 1 Discovery Meeting: FEMA staff and either FEMA’s contractors and/or department staff meet with representatives from the communities chosen for remapping to gather information on local priorities and any available engineering and topographic data
  • Step 2 Data Development: Information and data gathered at the scoping meeting is reviewed for compliance with FEMA’s mapping standards. New engineering studies are done if funding available.
  • Step 3 Preliminary FIRMs: Preliminary FIRMs are created using the gathered data. The preliminary maps are made available to local officials and the public for review during an open house.
  • Step 4 Expanded Appeal Process: A 90-day appeal period set by the NFIP during which the public can submit comments (base map feature changes) and appeals (Special Flood Hazard Area/regulatory floodway changes) to the preliminary FIRMs. Submittals are made to the community and then forwarded after review to the department for final evaluation. Changes are then made to the preliminary FIRMs to incorporate any valid comments and appeals.
  • Step 5 Final Map Creation: Once all changes are made to the preliminary FIRMs, the engineering data and maps are sent to FEMA for final map production. FEMA’s Map Service Center is responsible for providing the final maps and the Flood Insurance Study to the affected communities.
  • Step 6 Letter of Final Determination and Ordinance Adoption: FEMA is responsible for notifying the communities of the effective date of the FIRMs. Each community that will have new FIRM panels is sent a Letter of Final Determination (LFD). The LFD notifies the community that it has six months to amend the current floodplain ordinance

A detailed flow chart [PDF] outlines the mapping process, including a timeline.

Back to Top

Letters of Map Change

Letters of Map Amendment (LOMA), Letters of Map Revision (LOMR) and Letters of Map Revision Based on Fill (LOMR-F) are documents issued by FEMA that officially remove a property and/or structure from the floodplain for flood insurance purposes. They are collectively called Letters of Map Change (LOMC). To obtain a LOMC, the applicant must submit the required data for the property to FEMA. The required data may include surveys, maps, engineering studies, elevation certificates and aerial photography or other visual data. Some data may be obtained from local government offices (e.g., the city hall, county courthouse, etc.). In most cases, the applicant will need to hire a registered land surveyor to prepare an Elevation Certificate for the property. The length of FEMA’s review process is dependent on the complexity of the project.

LOMCs may be issued for a single structure/lot or multiple structures/lots. All LOMCs remove the flood insurance purchase requirement. A structure or lot removed from the floodplain by a LOMC is not subject to the requirements of the NFIP, but may still be subject to the requirements of the local floodplain ordinance.

Users should contact the FEMA Map Information Exchange [exit DNR] at 1-877-336-2627 for questions related to Letters of Map Change submittals.

Letter of map amendment

A LOMA [exit DNR] is typically a correction to a flood map and is issued based on better survey data showing that either a property’s natural lowest grade or the lowest grade adjacent to the structure is above the base flood elevation. A property owner will often request a LOMA after being informed by a lending institution that the property is believed to be within a floodplain. FEMA does not charge a fee for reviewing a LOMA.

Under certain circumstances, FEMA requires a Conditional Letter of Map Amendment (CLOMA). A CLOMA [exit DNR] is FEMA's comment on whether a proposed project would be excluded from the floodplain as shown on the flood map. The letter becomes effective on the date sent. It does not revise an effective flood map, but indicates whether the project, if built as proposed, would or would not be removed from the floodplain by FEMA if later submitted as a request for a Letter of Map Amendment (LOMA). FEMA does charge a fee for reviewing a CLOMA.

Letter of map amendment – Out as shown

A LOMA-OAS is issued when an applicant provides convincing visual evidence that a structure is outside of the mapped floodplain. FEMA issues a LOMA-OAS when a structure is incorrectly determined to be in the floodplain. A survey is not required as part of a LOMA-OAS application. FEMA does not charge a fee for reviewing a LOMA-OAS.

For more information on how to complete a LOMA-OAS contact Gary Heinrichs, DNR Floodplain planning program manager.

Letter of map revision

A LOMR [exit DNR] is a revision to a flood map based on technical engineering studies submitted by the applicant to FEMA. LOMRs are typically issued for complex or large scale projects such as subdivisions, stream relocations and road/bridge projects. FEMA charges a fee for reviewing a LOMR application.

Under certain circumstances, FEMA requires a Conditional Letter of Map Revision (CLOMR). A CLOMR is FEMA's comment on a proposed project that would affect the hydrologic and/or hydraulic characteristics of a flooding source and thus result in the modification of the existing regulatory floodway or effective Base Flood Elevations (BFE). There is no appeal period. The letter becomes effective on the date sent. This letter does not revise an effective NFIP map, it indicates whether the project, if built as proposed, would or would not be removed. FEMA charges a fee for reviewing a CLOMR application.

Letter of map revision based on fill

Under federal regulations, a property can be removed from a mapped floodplain if it is filled to an elevation that is at or above the base flood elevation. A LOMR-F is concurrence from FEMA that the data submitted by the applicant meets this standard and waives the flood insurance purchase requirement. FEMA charges a fee for reviewing a LOMR-F application.

Under certain circumstances, FEMA requires a Conditional Letter of Map Revision Based on Fill. A CLOMR-F is FEMA's comment on whether a proposed project involving the placement of fill would exclude an area from the flood map. The letter becomes effective on the date sent. This letter does not revise an effective NFIP map, but indicates whether the project, if built as proposed, would or would not be removed from the floodplain by FEMA if later submitted as a request for a Letter of Map Revision Based on Fill (LOMR-F). FEMA charges a fee for reviewing a CLOMR-F [exit DNR] application.

Under Wisconsin regulations, a property can only be removed from the floodplain if the building site is filled to the flood protection elevation, is contiguous to lands outside the floodplain and a land use permit for fill is obtained.

Unless a LOMR-F and a land use permit are obtained prior to the start of any construction on the property, state and federal regulations would still apply.

Community responsibilities

Communities are required to maintain copies of all Letters of Map Change (LOMC) issued by FEMA because they represent changes to the effective Flood Insurance Rate Map. LOMCs are usually filed with a community’s floodplain zoning map and other related technical data.

Copies of LOMCs can be obtained from local building officials, zoning administrators or FEMA. Instructions and forms for LOMCs, Letters of Determination Review and Elevation Certificates can be downloaded from FEMA’s website [exit DNR].

Engineering and modeling

The DNR engineering group does engineering studies as contractors under FEMA’s Risk MAP program. The studies are used to produce the Flood Insurance Studies and the Digital Flood Insurance Rate Maps.

The engineering data from the Flood Insurance Studies can be found on the department Surface Water Data Viewer. If the effective model is not on the Surface Water Data Viewer, then staff can assist users in determining whether or not engineering data exists.

Staff can answer specific technical questions on studies related to the floodplain. For most engineering hydraulic studies, HEC-RAS is the accepted model. A free copy of HEC-RAS can be downloaded from the US Army Corps of Engineers [exit DNR].

Staff reviews and approves engineering studies for compliance with NR 116 Wis. Admin. Code.

Users should contact the FEMA Map Information Exchange at 1-877-336-2627 for questions related to Letter of Map Change submittals.

Back to Top

Resources

More information on floodplain management.

Last Revised: Wednesday November 19 2014