Levee System Information for Stakeholders

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Floodplain Managers, Surveyors, Engineers, and Architects

Read general information about levees and 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 is updating and modernizing existing FIRMs for most of the United States.

Levee systems have been identified in over one-fourth of the counties receiving the modernized maps, called Digital Flood Insurance Rate Maps (DFIRMs). Therefore, FEMA has been working and continues to work with federal, state and local professionals and technical partners to accurately reflect the flood hazard and risk in the levee-impacted areas on the DFIRMs.

Levee System Mapping Requirements

On August 22, 2005, FEMA issued Procedure Memorandum No.34 (PM 34) to help clarify the responsibilities of community officials, levee owners or other parties seeking recognition of a levee system that is identified during a study/mapping project. PM 34 clarifies the existing procedures to provide information on levee systems, which were provided in Appendix H of FEMA's Guidelines and Specifications for Flood Hazard Mapping Partners. The procedures in PM 34 were intended to minimize delays in near-term studies/mapping projects and to help FEMA mapping partners and contractors properly address mapping issues in levee-impacted areas.

As part of a study/mapping project, a community/levee owner is responsible for providing data and documentation to show that a levee system meets the requirements of Section 65.10 of the NFIP regulations if the community/levee owner believes that levee system provides a 1-percent-annual-chance level of flood protection. Once the FEMA staff has received and reviewed the required data and documentation, FEMA will "accredit" the levee system with providing 1-percent-annual-chance flood protection. 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 DFIRM panel(s) as not providing 1-percent-annual-chance flood protection. 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.

The process of compiling and submitting Section 65.10-required data and documentation may cause delays in the release of more up-to-date flood hazard and risk information on DFIRM panels for other parts of a community or county. Therefore, PM 34 established a deadline to be issued to the community/levee owner for submitting the required data and documentation.

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

Provisionally Accredited Levee (PAL) Systems

To minimize the impact that mapping areas landward of levee systems could have on the Map Mod effort, FEMA issued Procedure Memorandum No. 43 (PM 43) on September 25, 2006. The clarifications provided in PM 43 and the guidelines document issued with it allow for the identification of PAL systems and for the issuance of preliminary and, in some cases, final effective DFIRMs while communities/levee owners are compiling and submitting the data and documentation required to show compliance with Section 65.10. PM 43 also provides a specified timeframe for communities and levee owners to submit the required data and documentation. The September 25 version of PM 43 outlined five scenarios in which the mapping process for selected studies/mapping projects with levee systems would be able to proceed while the community/levee owner acquires and submits the data and documentation required by Section 65.10.

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 impacted 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 and several attachments to clarify the procedures that FEMA, FEMA mapping partners and FEMA contractors are to follow for federal and non-federal levee system projects that are deficient on maintenance only. This revised version of PM 43 also provides communities/levee owners with a one-time only "maintenance deficiency correction period" of 1 year. The procedures for these levee systems are provided in the discussion of Scenarios A and C of the guidelines document issued with the revised version of PM 43.

Like the USACE, FEMA will notify community officials and/or levee owners, in writing, about its plans for mapping areas landward of levee systems. Templates for the notification letters and PAL agreements, as well as process flowcharts for Scenarios A and C, also were issued as attachments to the revised version of PM 43. Additional details on the guidance issued by the USACE are provided below.

On April 24, 2009, FEMA issued Procedure Memorandum No. 53 (PM 53), Guidance for Notification and Mapping of Expiring Provisionally Accredited Levee Designations. PM 53 provides clarified guidance for FEMA, FEMA contractor, and mapping partner staff related to communication with community officials, levee system owners and other stakeholders concerning impending PAL Expiration Dates. PM 53 also clarifies the procedures to be followed for updating DFIRMs after the PAL Expiration Date. FEMA also developed an informational Fact Sheet to summarize the requirements for expiring PAL system designations. PM 53, associated attachments and the Fact Sheet are accessible through links below

U.S. Army Corps of Engineers Levee System Guidance

FEMA and USACE management and staff are coordinating 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 memorandum helps to clarify the responsibilities of the USACE and FEMA staff for notifying levee owners about the condition of their levee systems and about the data and documentation required to accredit levee systems on NFIP flood maps. FEMA and USACE staff collaboratively developed this USACE memorandum and PM 43, which are intended to be companion documents for situations where levee systems in the USACE programs are being evaluated for accreditation on NFIP flood maps.

On January 18, 2007, USACE issued a memorandum to provide supplemental guidance for the inspection of levee systems in the USACE programs. The purpose of this memorandum is to provide a one-time-only "maintenance deficiency correction period" of 1 year, which will allow public sponsors of levee system projects time to correct maintenance deficiencies before the project is placed in an "inactive" status in the USACE Rehabilitation and Inspection Program and the project becomes ineligible for Public Law 84-99 rehabilitation assistance.

The USACE memorandums summarized above and other USACE levee system-related guidance may be accessed through the USACE National Flood Risk Management Program Website.

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.

To obtain information on and resources about the FEMA regulatory and procedural requirements, the benefits of FEMA issuing "flood protection restoration zone" or "adequate progress" determinations, and revising the affected FIRM or DFIRM panel(s) to show Zone AR or Zone A99 flood insurance risk zone designations, please visit the Levee System Construction and Restoration Projects page.

Guidance on Levee System Notation

In response to feedback provided by its mapping partners and other program stakeholders, FEMA reviewed its existing guidance regarding the mapping of levee-impacted areas and determined that additional guidance was needed regarding the levee system notes that are to appear on the DFIRM panels on which accredited levee systems and PAL systems appear. FEMA issued the guidance on May 12, 2008, in the form of Procedure Memorandum No. 45 (PM 45), Revisions to Accredited Levee and Provisionally Accredited Levee Notations. FEMA's intent in issuing PM 45 was to provide greater clarity and consistency of risk messages related to areas impacted by accredited levee systems and PAL systems. As indicated in PM 45, the revised notes that will appear on the affected DFIRM panels in the vicinity of the accredited levee system or PAL system and in the Notes to Users section of the map frame must be applied to DFIRMs that will become effective on or after December 1, 2008.

FEMA developed a Fact Sheet to explain the revised notes; visual depictions of the revised notes also are provided on the previously referenced how-to checklist. PM 45, the Fact Sheet, and the how-to checklist are accessible through links below.

Additional Mapping and Communication Guidance Associated with Levee Systems

De-accreditation of a levee system in accordance with Appendix H of FEMA's Guidelines and Specifications for Flood Hazard Mapping Partners can be a long and expensive process to undertake within the limited timeframes and scope of the flood map production cycle. In addition, the de-accreditation process requires critical outreach and communication to those living and working in areas landward of a levee system that is being de-accredited.

In recognition of these issues, FEMA undertook the development of comprehensive practices for the flood hazard (engineering) analyses and mapping of flood hazards on the landward side of levee systems. In developing these practices, FEMA allowed for flexibility based on the relative risk to the landward side of the levee system while maintaining national consistency in the approach. The intention of these practices is to minimize delays and costs that would seriously impact studies/mapping projects and FEMA's ability to deliver improved flood hazard mapping

On April 24, 2009, FEMA issued Procedure Memorandum No. 52 (PM 52), Guidance for Mapping Processes Associated with Levee Systems. As attachments to PM 52, FEMA implemented two sets of guidelines to address the perceived needs related to the accreditation and de-accreditation of levee systems. One attachment, "Guidelines for Mapping Landward of Levee Systems," provides mapping alternatives associated with accredited, non-accredited and de-accredited levee systems. These guidelines, issued to clarify and enhance those described in Appendix H, provide options for the mapping of an impacted area landward of a levee system based on the relative risk to the landward side of the levee system. The second attachment, "Guidelines for the Notification Process for De-accredited Levees," lays out a nationally consistent stakeholder notification process, including sample form letters and a sample newspaper announcement.

Mapping Guidance for Non-Levee Embankments

On February 27, 2009, FEMA issued Procedure Memorandum No. 51 (PM 51), Guidance for Mapping of Non-Levee Embankments Previously Identified as Accredited. FEMA issued PM 51 because some effective versions of FIRMs and some preliminary versions of DFIRMs show areas in the vicinity of "non-levee embankments"—embankments that were not designed or constructed as flood-control structures, such as those for highways and railroads—as not being subject to inundation during the base (1-percent-annual-chance) flood. Because such embankments are not "levees" as defined in Section 59.1 of the NFIP regulations  (44 CFR 59.1), they cannot be accredited with providing flood protection in accordance with Section 65.10 (44 CFR 65.10) of the NFIP regulations.

PM 51 establishes a process for the FEMA re-evaluation of flood hazards and the remapping of those hazards for DFIRMs issued in Preliminary form since August 22, 2005, for which FEMA has not yet issued Letters of Final Determination. PM 51 also establishes a process for community review and re-evaluation of the flood hazards and mapping before and after the DFIRM becomes effective.

Useful Resources

The resources listed below will assist CTPs and other map makers in gaining a better understanding of the requirements for evaluating levee systems and for mapping the flood hazard and risk in levee-impacted areas. These resources and an array of other useful FEMA, NFIP and Map Mod resources are now located in the FEMA Library.

For More Information

For more information or additional assistance:

Last Updated: 
07/24/2014 - 16:00
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