Who certifies levees in Dallas?

Understanding the process to “rate,” “certify” and “accredit” levees in Dallas.

Published Nov. 9, 2011

Two federal agencies and one municipality have interlocking roles and responsibilities for assessing levee capabilities: The U.S. Army Corps of Engineers, the City of Dallas and the Federal Emergency Management Agency. Key to grasping the process is an understanding of the words “rate,” “certify” and “accredit.” A different governmental unit is responsible for each.

Q. Who rates the levees?

A. The U.S. Army Corps of Engineers.

In Dallas, it is the U.S. Army Corps of Engineers’ responsibility to inspect and then rate Dallas Floodway components that protect the City from Trinity River flooding. The Dallas Floodway levees built in the 1920s were improved and raised by the Corps of Engineers in the 1950s to reduce risks in Dallas from a Standard Project Flood that has a 1-in-800 chance of happening in any given year (also commonly called a 800-year flood). Inspections conducted by the Corps of Engineers are for the purpose of evaluating the system’s ability to function and perform as originally designed, and determining eligibility for the Rehabilitation and Inspection Program under Public Law (P.L.) 84-99, which provides Federal assistance for repair of flood risk management structures in the event of damages caused by a flood event.

These inspections are not directly related to the certification of levees under the National Flood Insurance Program (NFIP) administered by the Federal Emergency Management Agency (FEMA). In other words, an “Unacceptable” rating from the Corps does not mean that the levees are decertified for the NFIP.

In 2009, the Corps’ Fort Worth District issued an “Unacceptable” rating for the Dallas Floodway in its Periodic Inspection No. 9 report as part of its national Levee Safety Program. Public safety is the No. 1 priority of this program.

An “Unacceptable” rating means the Dallas Floodway will not perform as originally designed and built – protection against the 800-year flood event as defined in the 1950s. The Corps and the City of Dallas are now jointly working to assess what Dallas Floodway improvements are needed to reduce risks from the current 800-year flood event and beyond.

Q. Who certifies the levees?

A. The City of Dallas is responsible for obtaining certification of the levees.

Certification of a levee system by a professional engineer is part of the process for obtaining accreditation by FEMA for the NFIP, and is based on the ability of the levee system to safely pass a 100-year flood event. A 100-year flood has 1-in-100 chance of occurring in any given year.

The City of Dallas has hired an engineer consulting firm to assess the Dallas Floodway and make recommendations on levee modifications required for certification. Upon completion of these fixes under the City of Dallas’ 100-year plan, a professional engineer certifies that adequate design and operation and maintenance systems are in place so that the levee system is capable of safely passing a 100-year flood event. This certification is then submitted to FEMA for accreditation.

Q. Who accredits the levees?

 A. The Federal Emergency Management Agency (FEMA).

A. The Federal Emergency Management Agency (FEMA).

FEMA is responsible for drawing the Flood Insurance Rate Maps. These maps are an important component of the National Flood Insurance Program that shows what areas of the City are protected from a 100-year flood. This program is designed to mitigate future disaster losses nationwide by encouraging sound community-enforced building and zoning ordinances and to protect property owners by providing access to affordable, federally backed flood insurance.

In 2009, at the same time the Corps rated the levees “Unacceptable” for the 800-year flood event, sufficient concerns with the levees were also identified to prompt the Corps to withdraw support for a 2006 letter used by the City’s previous consultant engineer in certifying the levees for the City of Dallas in 2007. As a result of the formal withdrawal of that letter, FEMA then de-accredited the levees. But that action alone did not change any insurance rates, mandates or rate maps under the National Flood Insurance Program.

FEMA is now redrawing the 100-year Flood Insurance Rate Maps for Dallas. The City of Dallas expects to have the levees repaired and certified prior to FEMA completing the revised maps. If FEMA accepts the City’s certification package, FEMA could accredit the Dallas Floodway and its Flood Insurance Rate Map would again show the levees provide protection from a 100-year flood.

If FEMA does not accredit the levees, the new 100-year floodplain map would be drawn to reflect the inability of the existing levees to provide 100-year level of protection. As such, some areas behind the existing levees would be within the new 100-year floodplain. Mandatory flood insurance would be required for structures with mortgages that are Federally backed, regulated or insured at the time the new floodplain map becomes effective. Zoning restrictions would also be required in these high-risk areas.

For further information

More information on the roles and responsibilities of federal and local government in levee inspection and accreditation is available from the U.S. Army Corps of Engineers here: http://www.mvs.usace.army.mil/me_levees/documents/USACE-FEMA2_3-15-10.pdf