New Orleans has problems with subsidence, or sinking, and flooding, thanks to its location. The city began as a French colony that lies between two bodies of water: Lake Pontchartrain and the Mississippi River. Furthermore, the shallow depression that the city is sitting on has an average elevation of 1.8 meters below sea level.
Because of this, the Big Easy has developed a means to keep the water out. It consists of levees, pumps, and upstream control structures assembled into a complicated system that keeps floods and water surges at bay.
Levees have been used by people for a very long time to tame rivers and oceans and keep them from taking over or destroying civilization. Also known as a dike, a levee is a man-made embankment that’s wider at the base and narrower at the top. It consists of clay or other less permeable soil to keep the overflow of rivers or ocean water from reaching human settlement. Levees can go on for many miles in a long strip, typically along a river, lake, or ocean.
The Height of New Orlean Levees
Because of its distinct geography, New Orleans has been at risk of flooding from the Mississippi River since its founding. In addition, it is also prone to flooding caused by storm surges from Lake Pontchartrain and Lake Borgne. Plus, its low-lying location can lead to poor drainage when heavy rains come, which is another reason for flooding in the city.
In the past, the routine flooding created natural levees. However, beyond the levees, the land slopes toward the city. So, the natural levees became problematic when the water level of the river rose and flowed over them.
In New Orleans, levees perform a dual function. They are used to keep Lake Pontchartrain’s water at bay and protect against floods from the Mississippi River. Now, to be effective, levees have to be at a certain height.
How tall a levee is or should be can vary, depending primarily on the storms that hit the area. In Holland, levees reach 30 feet (10 meters), but in New Orleans, levees along the Mississippi River have heights ranging from 10 to 20 feet (3 to 7 meters) tall.
New Orleans East Bank Levee System
According to the National Levee Database, the New Orleans East Bank levee system, which protects the city from flooding due to the Mississippi River and the Gulf of Mexico, has an average height of 22 feet (nearly 7 meters).
This levee system consists of seven segments across five parishes. It is made up of the Mississippi River Levees (MRL) and the Hurricane and Storm Damage Risk Reduction System (HSDRRS).
The MRL is one of the major features of the Mississippi River and Tributaries (MR&T) project, which was authorized by the 1928 Flood Control Act, a comprehensive flood risk management effort arising from the devastating 1927 flood. It provides comprehensive risk reduction, protection, and flood damage control via a network of levees and floodwalls, floodways, tributary basin improvements, and channel improvement and stabilization. The mainstream levee system includes more than 3,700 miles of embankments and walls from the head of the alluvial valley at Cape Girardeau, Missouri to Venice, Louisiana.
Meanwhile, the HSDRRS protects five parishes from 100-year level floods. It consists of some 350 miles of levees and floodwalls and 73 pumping stations.
- New Orleans Bank Maxent Subarea
The New Orleans Bank Maxent Subarea is located in Orleans Parish, Orleans East Sub-basin of the New Orleans East Bank Levee System. It includes the earthen embankment with sod and the Orleans Parish #18 (Maxent) Pump Station.
This levee system runs 4.8 miles (nearly 7 km) and aims to protect people and property from rainfall events by pumping water from populated areas into the adjacent wetlands. It has an average height of 5 feet (1.5 meters).
- New Orleans East Bank Forty Arpent Subarea
The New Orleans East Bank Forty Arpent Subarea runs 23.1 miles (approximately 37 km). It protects Violet in St. Bernard Parish. However, as of this writing, the National Levee Database has no data on the levee system’s height and flooding source.
New Orleans West Bank Levee System
The New Orleans West Bank Levee System is approximately 115 miles and is made up of Mississippi River Levees (MRL) and the Hurricane and Storm Damage Risk Reduction System (HSDRRS). The levee system has an average height of 17 feet (5 meters).
It is made up of 10 segments extending through four different parishes and maintained by five different levee districts. With approximately 93 miles of levees and 22 miles of floodwalls, this levee system protects the area from floods coming from the Gulf of Mexico and the Mississippi River.
- Donner Canal West Bank Sub System
This levee system protects the city from flooding from the Donner Canal and runs for 4.4 miles (about 7 km). Unfortunately, the National Levee Database has no data regarding the height of the levees in the Donner Canal West Bank Sub System, as of this writing.
- Lower Donner Canal
The Lower Donner Canal protects New Orleans from floods coming from the Gulf of Mexico. It runs for approximately 5.1 miles (around 8.2 km). Unfortunately, the National Levee Database has no data regarding the height of the levees in this system, as of this writing.
- East Jefferson System
The East Jefferson System protects Metairie in Jefferson Parish from flooding coming from the 17th Street Canal. The system features 2.4 miles (about 3.9 km). However, the National Levee Database has no data regarding the height of this levee system, as of this writing.
- Old Jackson Levee
This levee system protects New Orleans from flooding from the Gulf of Mexico. However, the National Levee Database has no data regarding the height of the levees in the Old Jackson Levee, as of this writing.
To recap, here are the levees in New Orleans that we’ve discussed and their corresponding heights.
Table 1. New Orleans Levees
| Levee System | Location | Flooding Source | Levee Length | Average Levee Height |
| New Orleans East Bank | New Orleans, Orleans Parish, Louisiana | Gulf of Mexico Mississippi River | 179.259 miles (around 288.50 km) | 22 feet (almost 7 meters) |
| New Orleans Bank Maxent Subarea | New Orleans, Orleans Parish, Louisiana | No data | 4.8 miles (nearly 7 km) | 5 feet (around 1.5 meters) |
| New Orleans East Bank Forty Arpent Subarea | Violet, St. Bernard Parish, Louisiana | No data | 23.1 miles (approximately 37 km) | No data |
| New Orleans West Bank Levee System | Poydras, St. Bernard Parish | Gulf of Mexico, Mississippi River | About 115 miles (approximately 185 km) | 17 feet (5 meters) |
| Donner Canal West Bank Sub System | New Orleans, Orleans Parish, Louisiana | Donner Canal | 4.4 miles (about 7 km) | No data |
| Lower Donner Canal | Belle Chasse, Plaquemines Parish, Louisiana | Gulf of Mexico | 5.1 miles (around 8.2 km) | No data |
| East Jefferson System | Metairie, Jefferson Parish, Louisiana | 17th Street Canal | 2.4 miles (about 3.9 km) | No data |
| Old Jackson Levee | New Orleans, St. Bernard Parish, Louisiana | Gulf of Mexico | 2.929 miles (4.7 km) | No data |
Source: National Levee Database