What is a levee? Exploring the Possibilities

Levee Definitions, Functions, and Failures

Two elderly people walking a path along a river
The asphalt-topped Lewiston-Clarkston Levee pathway, nearly 30 miles of recreation along the Snake River. Photo by Francis Dean, Deanpictures / Corbis Historical / Getty Images

A levee is a type of dam or wall, usually a man-made embankment, that acts as a barrier between water and property. It is often a raised berm that runs along a river or canal. Levees reinforce a river's banks and help prevent flooding. By constricting and confining the flow, however, levees can also increase the speed of the water.

Levees can "fail" in at least two ways: (1) the structure is not high enough to stop rising waters, and (2) the structure is not strong enough to hold back rising waters.

When a levee breaks at a weakened area, the levee is considered "breached," and water flows through the breach or hole.

Definition of Levee:

"A man-made structure, usually an earthen embankment or concrete floodwall, designed and constructed in accordance with sound engineering practices to contain, control, or divert the flow of water so as to provide reasonable assurance of excluding temporary flooding from the leveed area."—US Army Corps of Engineers

Types of Levees:

Levees can be natural or man-made. A natural levee is formed when sediment settles on the river bank, raising the level of the land around the river.

To construct a man-made levee, workers pile dirt or concrete along the river banks, creating an embankment. This embankment is flat at the top, and slopes at an angle down to the water. For added strength, sandbags are sometimes placed over dirt embankments.

Origin of the Word:

The word levee (pronounced LEV-ee) is an Americanism—that is, a word used in the United States, but not anywhere else in the world.

It should come as no surprise that "levee" originated in the great port city of New Orleans, Louisiana, at the mouth of the flood-prone Mississippi River. Coming from the French word levée and the French verb lever meaning "to raise," handmade embankments to protect farms from seasonal floods became known as levees.

Levees Around the World:

A levee is also known as a floodbank, stopbank, embarkment, and storm barrier.

Although the structure goes by different names, levees protect the land in many parts of the world. In Europe, levees prevent flooding along the Po, Vistula, and Danube rivers. In the United States, you will find important levee systems along the Mississippi, Snake, and Sacramento Rivers.

In California, an aging levee system is used in Sacramento and the Sacramento-San Joaquin Delta. Poor maintenance of the Sacramento levees have made the area prone to flooding.

Global warming has brought stronger storms and greater risks of flooding. Engineers are seeking alternatives to levees for flood control. The answer may lie in modern flood control technologies used in England, Europe, and Japan.

Levees, New Orleans, and Hurricane Katrina:

New Orleans, Louisiana, is largely below sea level. The systematic construction of its levees began in the 19th century and continued into the 20th century as the federal government became more involved with engineering and funding. In August 2005, several levees along waterways of Lake Ponchartrain failed, and water covered 80% of New Orleans. The US Army Corps of Engineers designed the levees to withstand the forces of a fast-blowing "Category 3" storm; they weren't strong enough to survive the "Category 4" Hurricane Katrina.

A full year before Hurricane Katrina slammed into the Gulf Coast, Walter Maestri, the emergency management chief for Jefferson Parish, Louisiana, was quoted in the New Orleans Times-Picayune:

"It appears that the money has been moved in the president’s budget to handle homeland security and the war in Iraq, and I suppose that’s the price we pay. Nobody locally is happy that the levees can’t be finished, and we are doing everything we can to make the case that this is a security issue for us."—June 8, 2004 (one year before Hurricane Katrina)

The Future of Levees:

Today's levees are being engineered for resilience and built for double duty—protection when needed and recreation in the off-season. Creating a levee system has become a partnership among communities, counties, states, and federal government entities.

Risk assessment, construction costs, and insurance liabilities combine in a complex soup of action and inaction for these public works projects. The building of levees to mitigate flooding will continue to be an issue as communities plan and build for extreme weather events, a predictable unpredictability from climate change.

Sources: "USACE Program Levees," US Army Corps of Engineers at www.usace.army.mil/Missions/CivilWorks/LeveeSafetyProgram/USACEProgramLevees.aspx; "United States of Shame," by Maureen Dowd, The New York Times, September 3, 2005 [accessed August 12, 2016]