Rebuilt levees don’t meet goal to protect New Orleans against Category 5 hurricane

Print More

The Lens has partnered with PolitiFact for the 10th anniversary of Hurricane Katrina to see if President Barack Obama has followed through on his campaign promises about the storm and the city of New Orleans. 

Pledge: Strengthen the levees in New Orleans:

Will ensure that New Orleans has a levee and pumping system to protect the city against a 100-year storm by 2011, with the ultimate goal of protecting the entire city from a Category 5 storm.

Ruling: Compromise


New Orleans is now protected against a 100-year storm, but that doesn’t mean the city is invulnerable to another Katrina.

The $14.5 billion system was in place by 2011, although it wasn’t quite finished. Those pumping stations were only temporary; the permanent ones are not expected to be finished until 2017.

Even so, the pumping stations were built close to Lake Pontchartrain, where they can block another storm surge from using the drainage canals as a highway into the city, as happened during Katrina.

Yet the city’s 100-year protection isn’t as impressive once you know that Congress originally called for a system that would guard the city against a much stronger storm.

In 1965, Congress ordered the U.S. Army Corps of Engineers to provide the city with a system that could withstand a 200- to 300-year storm. Those “year” designations are based on the storm history of a particular area. A 100-year storm has a 1 percent chance of occurring in any year.

The corps considered Katrina a 400-year storm, or a low Category 5 event, when it reached  New Orleans.

After Katrina, New Orleans and Louisiana politicians wanted a Category 5 system. Two factors led them to settle for less: The Bush administration did not want to pay for the stronger system, and it was important to build something quickly.

City and state leaders worried that no one would re-invest in the city until it qualified for federal flood insurance, which requires 100-year protection, said Mark Davis, director of the Tulane Institute on Water Resources Law & Policy. Anxious that it could take years to get something stronger, the city and state accepted what they could get from Washington.

The new 100-year system, however, is almost certainly stronger than the one in place before the storm. Though the old levee system was supposedly built for a 200- to 300-year storm, Katrina revealed serious engineering and construction weaknesses that caused catastrophic failures.

Plans are underway to “armor” the new levees with a protective layer. Once that’s done, they’re expected to be strong enough to withstand a 500-year storm without collapsing — although anything stronger than a 100-year storm probably would push water over the top.

Fortunately, in most storms, that wouldn’t be catastrophic because storm surge usually lasts only a few hours. Minor flooding could be pumped out by the city’s drainage system.

In the immediate aftermath of Katrina, the Bush administration said it would look at Category 5 protection in the future.

Obama elevated that to an “ultimate goal.” But there’s been little progress.

Before we go further, you should know that there’s no way to convert a 100- or 500-year storm to the category 1-5 system you’re used to hearing about. It’s not like Celsius and Fahrenheit.

Moreover, experts and engineers no longer refer to the category of a hurricane when discussing storm surge. The category system is based largely on wind speed, and experience has shown that a Category 1 storm can push as much water onshore as a Category 3 storm.

Even so, experts agree that the storm surge from a Category 5 hurricane would be greater than a 100-year storm.

At the direction of Congress, in 2006 the corps produced a report saying a Category 5 system around New Orleans would require 30-foot levees and cost about $11 billion. Levees and floodwalls around New Orleans range from 10.5 to 30 feet high.

No further action has been taken to build a Category 5 system around New Orleans.

John Barry, former vice president of the regional levee system responsible for New Orleans, was actively involved with the state’s congressional delegation in lobbying for the new levee system. He couldn’t recall any further discussion of building a Category 5 system.

The new levees and floodwalls around New Orleans would provide some protection in a Category 5 storm. With armoring, the corps says levees wouldn’t collapse in a 500-year storm, which would prevent a Katrina-level disaster.

But water would almost certainly pour over the top of the levees in many parts of the city in a Category 5 hurricane. Depending on how much water came into the city and how hard it rained, the city’s pumping system may be able to floodwaters from reaching houses.

We rate this a Compromise.

Sources

Email Interview with John Barry, Aug. 7, 2015

The Lens, “Bermuda grass is a cheap way to resist erosion — but it may not be enough,” Nov. 5, 2013

The Lens, “New Orleans’ flood protection system: Stronger than ever, weaker than it was supposed to be,” May 15, 2015

U.S. Army Corps of Engineers, Louisiana Coastal Protection and Restoration Final Report, June 2009

The Washington Post, “A Bush loyalist tackles Katrina recovery,” Nov. 21, 2011


Visit PolitiFact.com for prior updates on this pledge and to learn more about its ratings.

Help us report this story     Report an error    
The Lens' donors and partners may be mentioned or have a stake in the stories we cover.