Speak the language
From breach to T-wall: the words you need to understand why the levees broke.
- 8/29 Investigation
- An independent, bipartisan review of the 2005 flood protection failures and the decision making that led to them, proposed by Levees.org in 2007. Bills were filed in Congress but did not pass. Read more →
- ABET
- The organization that accredits college engineering programs in the United States. Levees.org's Engineering Failures Education campaign asks ABET to require instruction on past engineering failures. Read more →
- Army Corps of Engineers (USACE) (the Army Corps, the Corps)
- The federal agency that, under the Flood Control Act of 1965, was solely responsible for designing and building the hurricane protection for metro New Orleans. More than 98% of its employees are civilians. Read more →
- Barrier plan
- A 1960s–70s Army Corps plan for massive sea gates at the Rigolets and Chef Menteur passes east of New Orleans. The Corps abandoned it after a court found its four-page environmental impact statement inadequate, concluding higher levees were cheaper and less damaging. Read more →
- Breach
- An opening where a levee or floodwall has broken and water flows through. Different from overtopping, where water pours over the top of a structure that is still standing.
- The Louisiana state agency created after 2005 to serve as the single local sponsor for federal hurricane protection and to lead coastal restoration. Read more →
- Contraflow
- Reversing the inbound lanes of highways so all lanes carry traffic out of the city during an evacuation. Louisiana's improved contraflow plan helped evacuate about 93% of the New Orleans region before Katrina. Read more →
- Decision-Making Chronology
- A 333-page report by Douglas Woolley and Leonard Shabman (2008), prepared for the Army Corps, explaining why the New Orleans hurricane protection was built as it was. It documents the botched E-99 study. Levees.org calls it the preeminent report on the flooding. Read more →
- Drainage (outfall) canals
- The 17th Street, Orleans Avenue and London Avenue Canals, which carry rainwater pumped out of New Orleans north to Lake Pontchartrain. Storm surge from the lake could enter them; the walls along two of them failed. Read more →
- E-99 study
- A sheet pile load test the Army Corps began in 1985 near Morgan City. The Corps misinterpreted the results and concluded sheet piles need not be driven deeper than about 17 feet, instead of 31 to 46 feet. Read more →
- Engineering Failures Education (EFE)
- Levees.org's public safety campaign, launched in 2023, to require that all U.S. students earning a bachelor's degree in engineering learn about engineering failures and their lessons. Read more →
- Federal flood
- A term used by Levees.org and others for the 2005 flooding of metro New Orleans, emphasizing that it was caused by the failure of a federal project. Read more →
- Flood Control Act of 1928
- A federal law whose Section 702c makes the United States immune from liability for flood damage. It is why the Army Corps paid no damages even after a judge found it responsible. Read more →
- Flood Control Act of 1965
- The law, passed after Hurricane Betsy, that authorized the Lake Pontchartrain and Vicinity Hurricane Protection Project and put the Army Corps in charge of designing and building it. Read more →
- Floodwall
- A concrete-and-steel wall built on top of or within a levee to raise its height where there is no room to make the earthen levee wider.
- Funnel effect
- The amplification of storm surge where the levees of the MR-GO and the Gulf Intracoastal Waterway converge, pushing water toward the Industrial Canal. Read more →
- Gulf Intracoastal Waterway (GIWW)
- A federal navigation channel along the Gulf Coast. Levees along it, built with sand and shell, washed away and flooded New Orleans East. Read more →
- High walls plan (parallel protection, high level plan)
- The option of raising the walls along the drainage canals, rather than building gates at their mouths. The Corps chose it for the 17th Street Canal; Congress ordered it for the London Avenue and Orleans Avenue Canals. Read more →
- I-wall
- A floodwall made of steel sheet piling driven into a levee and capped with concrete, shaped like the letter I. The I-walls on the 17th Street and London Avenue Canals failed below their design load because the sheet piling was too short. Read more →
- Independent Levee Investigation Team (ILIT)
- The first major investigation (2006), funded by the National Science Foundation and led by Raymond Seed, Robert Bea and J. David Rogers. Its conclusion that the Orleans Levee Board shared blame was retracted in 2015. Read more →
- Industrial Canal (Inner Harbor Navigation Canal (IHNC))
- A 5.5-mile navigation canal, opened in 1923, connecting Lake Pontchartrain to the Mississippi River. Its floodwalls breached in several places, flooding the Lower Ninth Ward and Upper Ninth Ward. Read more →
- Interagency Performance Evaluation Task Force (IPET)
- The official investigation of the levee failures, convened and managed by the Army Corps itself. Its final report (2009) admits the system did not perform as designed. The Corps removed it from its website in 2019. Read more →
- Katrina shorthand
- Describing the flooding of New Orleans as if the hurricane alone caused it — for example, “Katrina flooded New Orleans.” It strips human agency out of what happened and protects those who made mistakes. Read more →
- Lake Pontchartrain and Vicinity Hurricane Protection Project
- The system of levees and floodwalls around metro New Orleans authorized by Congress in 1965 and designed and built by the Army Corps. It was still incomplete in 2005. Read more →
- Levee
- An earthen embankment built to keep water out of an area. Sixty-two percent of Americans live in counties protected by levees. Read more →
- Local sponsor
- The local or state agency that shares the cost of a federal water project and maintains and operates it once built. Before 2006, the Orleans Levee Board was a local sponsor of the hurricane protection. Read more →
- Mississippi River Gulf Outlet (MR-GO)
- A 76-mile Army Corps shipping channel opened in 1965. Erosion widened it from 625 to as much as 3,000 feet and destroyed buffering wetlands, contributing to the flooding of St. Bernard Parish and the Lower Ninth Ward. Congress ordered it closed in 2008. Read more →
- Monolith
- A single 30-foot-long section of concrete floodwall. Read more →
- Orleans Levee Board (OLB) (Orleans Levee District)
- The local agency responsible, before 2006, for maintaining and operating the federal hurricane protection in Orleans Parish. It had no role in design or construction, and the Army Corps graded its maintenance “Outstanding” from 1959 to 2004. Read more →
- Overtopping
- When water rises above and flows over the top of a levee or floodwall. Well-built levees are designed to survive some overtopping; levees built of sand did not.
- Seal of Approval
- Recognition Levees.org gives reporters who accurately describe the 2005 flooding as caused by levee failure. Read more →
- Sewerage and Water Board (S&WB)
- The New Orleans agency that runs the city's drainage pumps, which move rainwater into the outfall canals.
- Sheet piling (sheet piles)
- Interlocking steel sheets driven deep into the ground to form the core of an I-wall. Their depth determines how much water pressure the wall can resist. Read more →
- The regional levee board created in 2006 to replace the Orleans, Lake Borgne Basin and East Jefferson levee boards on the east bank, the first in the nation to require members with flood control expertise. Read more →
- Sovereign immunity
- The legal principle that the government cannot be sued without its consent. Under the Flood Control Act of 1928, it shields the Army Corps from paying flood damages. Read more →
- T-wall
- A floodwall with a wide concrete base anchored by deep piles, shaped like an upside-down T. Much stronger than an I-wall and about three times more expensive; used to repair the breach sites. Read more →
- Water Policy (2015)
- The peer-reviewed paper by J. David Rogers, G. Paul Kemp, H.J. Bosworth Jr. and Raymond Seed, published in the journal of the World Water Council, that retracted the ILIT's wrong conclusions about the Orleans Levee Board. Read more →