Levee System Information for Stakeholders

State and Community Officials

Read general information about levee systems on the Levee System Introduction page.

Map Modernization and Levee Systems

As the Federal agency that is responsible for administering the National Flood Insurance Program (NFIP), the Federal Emergency Management Agency (FEMA) identifies flood hazards, assesses flood risks, and provides appropriate flood hazard and risk information to communities nationwide. This information is provided to communities in the form of maps, called Flood Insurance Rate Maps (FIRMs). FEMA has an effort underway, called Flood Map Modernization (Map Mod), to update and modernize existing effective FIRMs for most of the United States.

Levee systems have been identified in over one-fourth of the counties that will receive modernized maps—Digital Flood Insurance Rate Maps (DFIRMs)—as part of Map Mod. Therefore, FEMA has been working, and continues to work with Federal, State, and local professionals and technical partners to determine the flood protection and risk-reduction capabilities of the Nation's levee systems and to accurately reflect the flood hazard and risk in the levee-impacted areas on the DFIRMs.

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Levee System Assessment Requirements

Some levee systems are shown on effective FIRMs as providing protection from the 1 percent-annual-chance flood event (sometimes called the base, or 100-year, flood). To determine whether the levee systems shown on DFIRMs still provide that level of protection, the levee system must be certified. FEMA issued Procedure Memorandum No. 34 (PM 34) to clarify the levee system certification requirements. PM 34, which clarified procedures documented in Appendix H of FEMA's Guidelines and Specifications for Flood Hazard Mapping Partners, requires levee owners to obtain and submit certain data and documentation to show that the levee systems continue to provide 1-percent-annual-chance flood protection. Once FEMA has received and reviewed the required levee data and documentation, FEMA will "accredit" the levee system and will revise the affected FIRM or DFIRM panel(s) to show the area behind the levee system as having a moderate flood risk. FEMA will label the levee-impacted area as Zone X (shaded).

If FEMA does not receive the data and documentation required to show compliance with Section 65.10, FEMA will "de-accredit" the levee system – that is, FEMA will show the levee system on the affected FIRM or DFIRM panel(s) as not providing protection from the 1-percent-annual-chance flood. FEMA will label the impacted area behind the levee system as Zone A or Zone AE, depending on whether an approximate engineering study or detailed engineering study was performed for the flooding source.

To assist community officials and levee owners with the compilation and submittal of the required levee data and documentation, FEMA developed a "how-to" checklist for floodplain managers and engineers titled Meeting the Criteria for Accrediting Levees on NFIP Flood Maps: How-To Guide for Floodplain Managers and Engineers.

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Procedures for Documenting Flood Risk

The compilation and submittal of the Section 65.10-required data and documentation can be a time-consuming process. Therefore, FEMA clarified the procedures for documenting flood risk in Procedure Memorandum No. 43 (PM 43). Under the clarified procedures, communities/levee owners will have up to 24 months to obtain and submit the required data and documentation. In the meantime, their levee system(s) will be considered provisionally accredited, and FEMA will designate most or all of the area behind the levee system as Zone X (shaded) on the DFIRM. In the interest of public safety, FEMA also will show a note clarifying the provisional nature of this zone designation on the DFIRM.

On March 16, 2007, FEMA issued a revised version of PM 43, with several attachments, to further clarify the procedures to be followed for Federal and non-Federal levee system projects that are maintenance deficient. The U.S. Army Corps of Engineers (USACE) is providing qualifying communities/levee owners with a one-time-only "maintenance deficiency correction period" of 1 year. For additional information on the revised version of PM 43, please visit the Floodplain Managers, Surveyors, Engineers, and Architects.

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U.S. Army Corps of Engineers Participation in Levee System Assessment

FEMA and USACE management and staff coordinate closely on levee system issues. On September 26, 2006, the USACE issued a memorandum that provides policy guidance for the inspection of levee systems in the USACE programs. The USACE memorandum helps clarify the responsibilities of USACE and FEMA staff for notifying levee owners of the condition of their levee systems. The USACE memorandum also explains the data required to credit levee systems with providing flood protection. FEMA and USACE staff collaboratively developed this memorandum and FEMA PM 43, which are intended to be companion documents to cover situations where levee systems in the USACE program are evaluated for accreditation on DFIRMs.

On January 18, 2007, the USACE issued supplemental policy guidance for the inspection of levee systems. For additional information on the USACE guidance, please visit the previously referenced Floodplain Managers, Surveyors, Engineers, and Architects page.

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Mapping Requirements for Levee System Construction and Restoration Projects

In the interest of public safety, communities, State agencies, and Federal agencies sometimes construct new levee systems to address flood hazards and reduce flood risks to the people and structures in certain communities or areas within a state. In other situations, communities, State agencies, or Federal agencies will undertake a project to restore the flood protection capabilities of a levee system that had previously provided 1-percent-annual-chance flood protection, but which had been found to no longer provide this level of flood protection. FEMA has established regulatory and procedural requirements for the mapping of areas impacted by levee system construction and restoration projects.

The Levee System Construction and Restoration Projects page contains information and resources related to FEMA regulatory and procedural requirements. This page also outlines the benefits of including FEMA flood protection restoration zones and adequate progress determinations, shown as Zone AR and Zone A99, on FIRM and DFIRM panels.

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Useful Resources

The resources listed below will assist State and community officials in gaining a better understanding of levee systems and the flood risk in levee-impacted areas. These resources and an array of other useful FEMA, NFIP, and Map Mod resources are located in the FEMA Library.

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Information on Outreach Best Practices

FEMA encourages State and community officials to read the Outreach Best Practice, titled Silver Jackets: Bringing Agencies Together for the Benefit of Communities, which highlights an interagency approach to increase communications between government agencies for the benefit of States and communities.

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For More Information

For more information or additional assistance:

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Return to the Levee System Introduction page.

Last Modified: Tuesday, 07-Oct-2008 10:33:25 EDT

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