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

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.


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.

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About Bob Marshall

From 2013 to 2017, Bob Marshall covered environmental issues for The Lens, with a special focus on coastal restoration and wetlands. While at The Times-Picayune, his work chronicling the people, stories and issues of Louisiana’s wetlands was recognized with two Pulitzer Prizes and other awards. In 2012 Marshall was a member of the inaugural class inducted into the Loyola University School of Communications Den of Distinction.

  • nickelndime

    Gawd of the 7th Ward! St. Claude, have mercy. WE (my ASP and I) love you guys at THE LENS. Well, WE gots to get to our 7th job b4 5:30 AM just to keep up with Erroll the One A$$e$$or.
    08/20/2015 4:35 AM DST USA

  • nickelndime

    General rule: Stock up on bottled water and canned food. After that, “It’s every man for himself.”
    Sound familiar – 10 years after Katrina?
    08/20/2015 4:47 AM DST USA

  • nickelndime

    Could Mitch the Mayor have (expletive deleted) this up any more than he has done? That’s a riddle, Son. Well, he had a lot of help.
    08/20/2015 4:51 AM DST USA

  • nickelndime

    Nineteen minutes! Did you make it to the breaker box, Ralphie?
    Yes, WE know that HOME MART is under siege by thieves.
    ASP is on the floor!
    Well, back on the clock,
    GPS OFF.
    08/20/2015 5:08 AM DST USA

  • nickelndime

    Damn, You, THE LENS, guys is really good. Gots to give you props on dat.
    See you at Mary’s ACE Hardware on N. Rampart. ASP loves 30-minute free parking, 08/20/2015 5:23 AM DST USA

  • KC King

    This article reflects some serious “bad thinking” about best science-based flood resilience and safety concepts by continuing to confuse flood insurance subsidy (100 year flood) measures with sound engineering safety. If Katrina taught us anything. it was that historical “averaging” was a flawed measure of future extreme storm destructive power. Even the Corps now asserts that levees alone will never provide adequate protection against storm effects of the Katrina class. The Corps strongly recommends a balance “total system” of structural, non-structural and procedural (evacuation) measures to adequately protect our city and, more importantly, our residents.

    This 100 year protection “myth” was explicity debunked by National Academy of Science panel recommended that FEMA find a better way to communicate flood risk , In fact, if President Obama committed to perform an act that even his Engineers don’t recommend we have a different kind of problem.

    The assertion that “New Orleans and Louisiana politicians wanted a Category 5 system” is not supported by the realities of local conservative politics. The Greater New Orleans, Inc organization and it political anti-realistic insurance rate advocating front, Coalition for Sustainable Flood Insurance (CSFI) use wing-nut science to claim that insurance rates should go down because New Orleans will never flood again. If GNO, Inc CEO Michael Hecht testifies that insurance rates are actuarially questionable, why is the Flood Insurance Program test of billions in the hole?

    The reality is that the realtor, developer, banker and builder members of GNO, Inc made unfathomable profits from rebuilding a devastated New Orleans and want to put safety last so they can do it again.

    Finally the Corps’ own Independent Performance Evaluation Team (IPET) for Katrina found the the root cause of Katrina, the catastrophe was that our flood protection “system” was a “system in name only” and should have had used best systems integration practices to ensure that the “whole was stronger than its parts”. The City, and its political and thought leaders, have yet to figure out what the IPET meant.

  • dimdingledon

    You hit the nail on the head. The entire levee system was a scam to get working class people back to New Orleans so businessmen in New Orleans would not lose their businesses. The new levees are a joke. Barry and the SLFPAE did not even look at the storm surge model or the levee designs of the new system until they were pressured to by citizens after construction was completed. The new levee system does not provide the protection we were promised. If one were to look at it closely, first of all the joint probability method that they used knew land would erode yet did not take this into account in determining flood threats. The assumptions for the model were so flawed. Even storms with the so-called 100 year level of protection, storms equal to or less than the 100 year storm can overtop the new levees. The subsidence already has some parts of the system below the required 100- year elevations on the levees. The biggest evidence of a scam is the price of flood insurance premiums residents pay for flood insurance. If the Corps provided us with so-called 100-year level of protection, then why does the Corps tell FEMA so much of the New Orleans metropolitan area is in a flood zone and does not meet 100-year protection?

  • dimdingledon

    I just hope some one in the media has the courage to expose this scam of the new levee system during the 10 year anniversary when all the eyes of the world are watching.

  • nickelndime

    Those Campaign Promises must have had some spectacular “wording” to be interpreted as PROMISE KEPT. WE just don’t SEE IT that way.
    08/23/2015 1:01 AM DST USA

  • nickelndime

    “Rebuilt levees”! Is that like re-conditioned stereo equipment, air-conditioners, microwaves, alarm systems, refrigerators….on and on and on and on.
    How would we rate your level of confidence in the re-built/re-conditioned levee system in New Orleans on a CATEGORY LEVEL of 1 to 10? 1 as being “Not Confident At All” and 10 being “I am HIGH as a kite and don’t even know what in the hell you are even asking,” with a Category 5 Response being, “Oh (expletive deleted) Son, gas up da car and let’s get da hell outta here.”
    08/23/2015 1:13 AM DST USA

  • Tim

    You clearly don’t understand that there are different threats of flooding. The levees and flood walls that circle the city provide perimeter protection only. They keep water from storm surge and waves out of the city with a 1% chance per year of exceedence. But that’s not the whole story. The city can also flood due to rainfall. We rely on pumps to reduce that risk. When FEMA and the Corps say your house inside the levees is in a flood zone, it’s because of rain, not hurricanes. Remember May 3rd and May 8th floods? Levees, good or flawed, had nothing to do with that. Hope this helps.



  • dimdingledon


    The Corps 100 year design included flooding from two sources: overtopping of the levees during storms and rainfall. Unfortunately the Corps botched it on both.

    First the overtopping. The Corps assumed an over topping rate of 0.1 cubic feet per second per foot of floodwall or levee across the system. This water will flow into the protected area and has to be pumped out by the S&WB pump stations. This reduces the amount of rainfall the S&WB pump stations can pump out. Also the assumptions made by the Corps for settlement and sea level rise have already been proven to be inaccurate. As a result the levees are not as high as the should be and more over topping will occur than assumed as a result. Also, the Corps joint probability method used to determine the required levee heights did not account for our eroding coast even though they knew about it. This means actual storm surges will be higher than the ones modeled because there physically will not be land to reduce the energy in the storm surges as was modeled by the Corps.

    Next the rainfall. The Corps used a 10 year rainfall event to design the flood protection system instead of the 100 year rainfall event. This one is self explanatory on why that was a screw up.

    But that is the reality of the new flood protection system. One need only ask, if the Corps designed a 100 year flood protection system, then why are our flood insurance premiums so high and why is so much of the metropolitan area located behind the new system considered high risk flood zones?

    Answer: The Corps screwed up AGAIN!

  • Tim

    Sorry, but you do not fully understand what you are writing about. You certainly know more than the average citizen, but there are significant gaps in your knowledge of rainfall, storm surge and waves, and what is being done to address those threats.

    You ask again, “…why is so much of the metropolitan area located behind the new system considered high risk flood zones?” I tried to explain to you that flooding from storm surge and waves during a hurricane is separate and independent from rainfall events like we saw on May 3rd and May 8th. Do you understand and agree with that point? You continue to say that maps showing flood zones are an admission of bad levees. That is completely incorrect.

    Interior drainage in New Orleans was designed and built by the City of New Orleans. What rainfall event do you think the city’s drainage system is designed to handle? Spoiler: not a 100-year rainfall event. That’s why FEMA shows flood zones on the 100-year flood map. Even with 50-foot-tall levees, there would still be flood zones in New Orleans. Even if hurricanes went extinct and never hit us again, there would still be flood zones in New Orleans.

  • dimdingledon

    The Corps model for the storm surge included the S&WB pump stations. They spent millions repairing stations because it would be part of the Corps plan and are spending about $650 million on the pump stations at the mouths of the outfall canals. The outfall canals between the existing S&WB pump stations and the new ones at the lakefront limit how much S&WB can pump. This means the S&WB can’t pump out rainwater because of poor floodwalls along the outfall canals. The Corps calls it the safe water elevation it should actually be called the elevation before the walls fall again. The Corps also screwed up with the rainfall using a low intensity rainfall event like the 10 year event instead of the 100 year rainfall intensity. The S&WB system is only designed for a 10 year rainfall intensity. So if we added the overtopping that occurs during the hurricanes to the 10 year rainfall there is no way the system works or no way the city does not flood. THe S$WB system gets overwhelmed. If the Corps did their modeling correctly and accounted for the 100 year rainfall event with the 100 year surge event, the city would be protected from all 100 year floods and our flood insurance premiums would reflect it. So what the Corps did was provide less than real 100 year protection. The Corps new this and did it anyway. They under designed the system intentionally to cut costs. And the Doody Barry led SLFPA-E just let them do it.

  • dimdingledon

    Perhaps you should look at the Corps inundation maps that show how deep the flood waters will get from storm surges overtopping the new levees. And it isn’t from rainfall.

  • dimdingledon

    Who is the president if the S&WB? Mitch Landrieu.
    Who did Landrieu appoint to his flood advisory committee? Doody and BArry the two least technically knowledgeable members and leaders of the SLFPAE. Now you see why we got such a bad system that does not provide the protection we were promised?

  • nickelndime

    Mitchell Landrieu is president of the Sewerage and Water Board of New Orleans!!! Well, that certainly explains the (expletive deleted expletive deleted deleted) expletive.
    Is that why WE can’t get a meter reading – among other things? The grass is cut. The ants have been fed sugar in the adjoining lot. WE even put out a chair and a self-service lemonade stand – with disposable cups and a waste basket. WE also put up a sign – PLEASE READ ME!
    WDa(expletive deleted)!
    08/24/2015 2:20 AM DST USA

  • nickelndime

    The “black limousine” list is growing – Basin Street – out back – 400 block. WE are going to need a fleet. However, WE might have to throw Walt Leger, III, out, because Walt is beginning to look like an ant at a picnic.
    08/24/2015 2:26 AM DST USA

  • nickelndime

    It is hard to read the Corps inundation maps under water – but WE will do our best.
    My ASP is snorkeling around.
    08/24/2015 2:45 AM DST USA