New Orleans is surrounded by a massive ring of levees and floodwalls that forms one of the largest flood protection systems in the world. Called the Hurricane and Storm Damage Risk Reduction System (HSDRRS), it spans 350 miles of levees and floodwalls across southeast Louisiana, encircling the city on nearly every side to hold back water from Lake Pontchartrain, the Mississippi River, Lake Borgne, and the Gulf of Mexico.
The Ring of Protection: How the System Is Laid Out
Think of the levee system as a series of connected loops that wrap around the greater New Orleans metro area. The city sits in a bowl, with most neighborhoods at or below sea level, so the levees form a continuous perimeter. Water threatens from multiple directions: Lake Pontchartrain to the north, the Mississippi River cutting through the center, wetlands and Lake Borgne to the east, and bayous and canals to the south and west.
The system includes not just earthen levees but also concrete floodwalls, massive surge barriers, canal closure structures with pumps, and gated outlets. In total, it incorporates 73 pumping stations, 3 canal closure structures with pumps, and 4 gated outlets, all working together to keep storm surge and rainwater out of populated areas.
Lake Pontchartrain Lakefront Levees
The northern edge of New Orleans is defined by a long stretch of levees running along the southern shore of Lake Pontchartrain. These levees protect Jefferson Parish and Orleans Parish from storm surge that pushes south across the lake during hurricanes. Congress first authorized this lakefront protection in 1965, and the levees were originally designed to reach between 9.3 and 13.5 feet high depending on local ground elevation.
In Jefferson Parish, the lakefront section includes a 3.5-mile floodwall along the Jefferson-St. Charles Parish line plus 10 miles of levees, floodwalls, floodgates, and fronting protection. Orleans Parish has its own enlarged lakefront levee running east along the shore. These lakefront levees are what stand between neighborhoods like Lakeview, Gentilly, and Metairie and the waters of the lake.
Mississippi River Levees
The Mississippi River levees are the oldest and most visible part of the system. They run along both banks of the river as it curves through the city, forming the familiar raised embankments that locals walk, jog, and bike on. A paved trail atop the levee stretches roughly 22 miles along the river, passing through areas across from the French Quarter and Woldenberg Park.
Unlike the hurricane protection levees, the river levees primarily guard against seasonal river flooding and high water stages rather than storm surge. They predate the modern HSDRRS and are maintained separately, though they function as part of the city’s overall flood defense.
New Orleans East
New Orleans East, the large area between the lakefront and the marshes leading to Lake Borgne, has approximately 25 miles of raised levee and about 2 miles of floodwall forming its perimeter. This section protects a sprawling residential area that was heavily damaged during Hurricane Katrina. The levees here loop around the eastern edge of the city, connecting with the lakefront system to the north and the Inner Harbor Navigation Canal defenses to the west.
St. Bernard Parish
Just south and east of New Orleans proper, St. Bernard Parish is protected by approximately 23 miles of floodwalls, roadway gates, and sector gates. This area was almost entirely inundated during Katrina, and the rebuilt defenses are significantly stronger. The parish’s protection ties into the massive surge barrier at the mouth of the Inner Harbor Navigation Canal.
The IHNC Surge Barrier
The single largest structure in the entire system is the Inner Harbor Navigation Canal (IHNC) Lake Borgne Surge Barrier, positioned at roughly 30.01°N, 89.90°W, east of the city where storm surge from the Gulf funnels toward New Orleans. This 1.8-mile concrete barrier wall stretches across the Mississippi River Gulf Outlet and the Golden Triangle Marsh. It includes a bypass barge gate and a flood control sector gate, each 150 feet wide, plus a 56-foot vertical lift gate at Bayou Bienvenue.
At the northern end of the Inner Harbor Navigation Canal, the Seabrook Floodgate Complex guards the connection to Lake Pontchartrain with a 95-foot navigable sector gate and two 50-foot vertical lift gates. Together, these two structures seal off one of the most vulnerable corridors that funneled catastrophic flooding into the city during Katrina.
The Three Outfall Canals
Three drainage canals cut through the heart of New Orleans on their way to Lake Pontchartrain: the 17th Street Canal, the Orleans Avenue Canal, and the London Avenue Canal. These canals carry rainwater pumped out of the city’s low-lying interior. During Katrina, floodwalls along the 17th Street and London Avenue canals failed, causing some of the worst flooding in neighborhoods like Lakeview and Gentilly.
The Army Corps of Engineers has since built permanent canal closures and pump stations at or near the mouth of each canal. These gated storm surge barriers close before a tropical storm arrives to block lake water from pushing into the canals, while pump stations continue moving rainwater out past the gates and into Lake Pontchartrain. The 17th Street Canal also serves as a drainage conduit for portions of Jefferson Parish, making its closure structure especially critical.
West Bank Levees
On the west side of the Mississippi River, neighborhoods like Algiers, Gretna, Harvey, and Marrero have their own levee system. The West Bank levees are made up of 10 segments extending through 4 parishes and maintained by 5 different levee districts. Key features include the Harvey Canal Floodwall, approximately 3.5 miles of concrete T-wall reaching 14 feet in elevation, and earthen levees along the Algiers Canal raised to about 8.2 feet.
The West Closure Complex is the anchor of the West Bank system. Located on the Gulf Intracoastal Waterway, it features a 225-foot navigable floodgate, a pumping station, sluice gates, and earthen levees. Farther south, the Bayou Segnette Complex includes a 56-foot sector gate, and the Eastern Tie-In provides a floodgate across Highway 23 and a stoplog gate across the Hero Canal. Plaquemines Parish has two additional sector gates near the Empire Floodgate and Empire Lock.
Who Manages the Levees
Two regional authorities oversee the levee system on each side of the river. The Southeast Louisiana Flood Protection Authority-East manages the East Jefferson Levee District, the Lake Borgne Basin Levee District, and the Orleans Levee District. The Southeast Louisiana Flood Protection Authority-West Bank covers the West Jefferson Levee District and the Algiers Levee District. The Army Corps of Engineers designed and built most of the modern system but handed ongoing maintenance responsibilities to these local authorities.
Areas Outside the System
Not every part of the New Orleans area sits inside the levee perimeter. Coastal areas outside the levee system remain vulnerable to flooding from waves during storms. Some lower-lying marshland and communities on the fringes of the metro area fall outside the 350-mile ring. If you live in or are visiting these areas, elevation and proximity to the nearest levee segment are worth understanding, since flood risk changes dramatically on either side of the protection boundary.