A Report by the American Society of Civil Engineers 

Hurricane Katrina External Review Panel

Christine F. Andersen, P.E., M.ASCE

Jurjen A. Battjes, Ph.D.

David E. Daniel, Ph.D., P.E., M.ASCE (Chair)

Billy Edge, Ph.D., P.E., F.ASCE

William Espey, Jr., Ph.D., P.E., M.ASCE, D.WRE

Robert B. Gilbert , Ph.D., P.E., M.ASCE

Thomas L. Jackson, P.E., F.ASCE, D.WRE

David Kennedy, P.E., F.ASCE

Dennis S. Mileti, Ph.D. 

James K. Mitchell, Sc.D., P.E., Hon.M.ASCE

Peter Nicholson, Ph.D., P.E., F.ASCE

Clifford A. Pugh, P.E., M.ASCE

George Tamaro, Jr., P.E., Hon.M.ASCE

Robert Traver, Ph.D., P.E., M.ASCE, D.WRE

ASCE Staff:

Joan Buhrman

Charles V. Dinges IV, Aff.M.ASCE

John E. Durrant, P.E., M.ASCE

Jane Howell

Lawrence H. Roth, P.E., G.E., F.ASCE

THE NEW ORLEANS 

HURRICANE PROTECTION SYSTEM:

What Went Wrong and Why
Library of Congress Cataloging-in-Publication Data

The New Orleans hurricane protection system : what went wrong and why : a report / by the American 

Society of Civil Engineers Hurricane Katrina External Review Panel.

 p. cm.

 ISBN-13: 978-0-7844-0893-3

 ISBN-10: 0-7844-0893-9

 1. Hurricane Katrina, 2005. 2. Building, Stormproof. 3. Hurricane protection. I. American Society of Civil 

Engineers. Hurricane Katrina External Review Panel. 

 TH1096.N49 2007

 627’.40976335--dc22

 2006031634

Published by American Society of Civil Engineers

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www.pubs.asce.org

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Copyright © 2007 by the American Society of Civil Engineers.

All Rights Reserved.

ISBN 13: 978-0-7844-0893-3

ISBN 10: 0-7844-0893-9

Manufactured in the United States of America.
THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why iii

Table of Contents

EXECUTIVE SUMMARY v

CHAPTER 1: Introduction 1

Interagency Performance Evaluation Taskforce. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

ASCE’s Hurricane Katrina External Review Panel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Other Teams of Investigators. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

This Report. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

CHAPTER 2: New Orleans 5

A City on the River. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Development on the Marshes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

New Orleans is Sinking. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

The People of New Orleans. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

A Cultural Treasure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

CHAPTER 3: Hurricane Katrina 11

The Storm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Wind, Water, and Waves. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

CHAPTER 4: Hurricane Protection System 17

Standard Project Hurricane. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Levees and Floodwalls. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Datums and Elevations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Interior Drainage and Pump Stations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

CHAPTER 5: The Levees Fail 25

Storm Surge Damage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Cracks in the System. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Flooding Ensues. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

A City Under Water. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Pump Stations Shut Down . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

CHAPTER 6: Consequences 33

Tragic Deaths. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Exposure, Injury, and Disease. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Catastrophic Financial Losses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Had the Hurricane Protection System Not Failed. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Cascading Financial Impacts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Prospects for Economic Growth. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Long Term Health and Safety. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Evacuees and Their Receiving Communities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

Impacts to New Orleans’s Culture. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

The Natural Environment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

CHAPTER 7: Direct Causes of the Catastrophe 47

17th Street Canal Breach. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Soil Strength Over-estimated. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

Factor of Safety. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

The Water-Filled Gap. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

London Avenue Canal South Breach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
iv THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why

Table of Contents

(continued)

Oversimplified Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

The Water-Filled Gap – Again. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

London Avenue Canal North Breach. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

Industrial Canal East Bank North Breach. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

Industrial Canal East Bank South Breach and 

Industrial Canal West Bank Breach. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

Industrial Canal West Bank South and All Other Levee Breaches. . . . . . . . . . . . . . . . . . . 57

Pumping System: Useless During Hurricane Katrina. . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

CHAPTER 8: Contributing Factors 61

Risk to New Orleans Not Fully Appreciated. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

Hurricane Protection System Constructed Piecemeal. . . . . . . . . . . . . . . . . . . . . . . . . . . 62

Hurricane Protection System Under-designed. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

Many Levees Not High Enough. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

No One Entity Is In Charge of Hurricane Protection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

External Peer Review Lacking. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

Funding Process Flawed. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

CHAPTER 9: What Must We Do Next? 73

Understand Risk and Embrace Safety. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

Re-evaluate and Fix the Hurricane Protection System. . . . . . . . . . . . . . . . . . . . . . . . . . . 76

Revamp the Management of the Hurricane Protection System. . . . . . . . . . . . . . . . . . . . 79

Demand Engineering Quality. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

Acknowledgements 83

Credits 84
v

Executive Summary

On the morning of August 29, 2005, Hurricane Katrina—one of the strongest 

storms ever to hit the coast of the United States—brought intense winds, high 

rainfall, waves, and storm surge to the Gulf of Mexico shores of Louisiana, 

Mississippi, and Alabama. Communities in all three states suffered damage, 

but this report focuses on the devastation to New Orleans and southeast 

Louisiana. 

New Orleans was built on low-lying marshland along the Mississippi 

River. Levees and floodwalls were built around the city and adjacent parishes 

to protect against flooding. During and after Hurricane Katrina, many of those 

levees and floodwalls were overtopped and several were breached, allowing 

billions of gallons of water from the Gulf of Mexico, Lake Borgne, and Lake 

Pontchartrain to flow into New Orleans and flood major portions of the city. 

As of August 2, 2006, 1,118 people were confirmed dead in Louisiana 

as a result of Hurricane Katrina. Another 135 people are still missing and 

presumed dead. Thousands of homes were destroyed. Direct damage to 

residential and non-residential property is estimated at $21 billion, damage to 

public infrastructure another $6.7 billion. Nearly half the region’s population 

has not yet returned after evacuating. Nearly 124 thousand jobs were lost, 

and the region’s economy was crippled. 

The catastrophic failure of New Orleans’s hurricane protection system 

represents one of the nation’s worst disasters ever. The members of the 

American Society of Civil Engineers (ASCE) Hurricane Katrina External Review 

Panel have conducted an in-depth review of the comprehensive work of the 

United States Army Corps of Engineers (USACE) Interagency Performance 

Evaluation Taskforce (IPET)—at the USACE’s request. The ASCE Hurricane 

Katrina External Review Panel’s findings and conclusions are presented in this 

report. 

A storm of Hurricane Katrina’s strength and intensity is expected to 

cause major flooding and damage. A large portion of the destruction from 

Hurricane Katrina was caused not only by the storm itself, however, but 

also by the storm’s exposure of engineering and engineering-related policy 

failures. The levees and floodwalls breached because of a combination of 

unfortunate choices and decisions, made over many years, at almost all levels 

of responsibility. 

There were two direct causes of the levee breaches: collapse of 

several levees with concrete floodwalls (called I-walls) because of the way 

they were designed, and overtopping, where water poured over the tops of 

the levees and floodwalls and eroded the structures away. Furthermore, the 

many existing pump stations that could have helped remove floodwaters 

were inoperable during and after the storm. 
vi THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why

The I-walls failed because the margin of safety used in the design 

process was too low—especially considering that the hurricane protection 

system was a critical life-safety structure. The engineering design did not 

account for the variability in the strength of soft soils beneath and adjacent 

to the levees. The designers failed to take into account a water-filled gap that 

developed behind the I-walls as they bowed outward from the forces exerted 

by the floodwaters. 

Some overtopping of levees is to be expected in a major storm. 

However, the levees were not armored or protected against erosion—an 

engineering choice of catastrophic consequences because this allowed the 

levees, some constructed of highly erodible soil, to be scoured away, allowing 

water to pour into New Orleans. 

In addition to these direct causes of the levee breaches, a number of 

other factors also contributed to the catastrophe:

• The risk to New Orleanians (i.e., the probability of failure combined 

with the consequences to human health and safety if that failure 

were to occur) was much higher than many people are generally 

willing to accept. Because these risks were not well understood 

or communicated effectively to the public, the importance of 

evacuating people and protecting property was under-estimated.

• The hurricane protection system was constructed as individual 

pieces—not as an interconnected system—with strong portions 

built adjacent to weak portions, some pump stations that could not 

withstand the hurricane forces, and many penetrations through the 

levees for roads, railroads, and utilities. Furthermore, the levees 

were not designed to withstand overtopping.

• The hurricane protection system was designed for meteorological 

conditions (barometric pressure and wind speed, for example) that 

were not as severe as the Weather Bureau and National Weather 

Service listed as being characteristic of a major Gulf Coast 

hurricane. 

• Levee builders used an incorrect datum to measure levee 

elevations—resulting in many levees not being built high enough. 

Some levees were built 1 to 2 feet lower than the intended 

design elevation. Furthermore, despite the acknowledged fact 

that New Orleans is subsiding (sinking), no measures were taken 

into account in the design to compensate for the subsidence by 

monitoring the levees and raising them up to the pre-subsidence 

design elevation.
THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why vii

• No single agency was in charge of hurricane protection in New 

Orleans. Rather, responsibility for the maintenance and operation 

of the levees and pump stations was spread over many federal, 

state, parish, and local agencies. This lack of inter-agency 

coordination led to many adverse consequences from Hurricane 

Katrina. 

• The hurricane protection system was funded on a project-byproject basis over many years. As a result, the system was 

constructed in a piecemeal fashion. In addition, there were 

pressures for tradeoffs and low-cost solutions that compromised 

quality, safety, and reliability. 

 

• The design of the New Orleans hurricane protection system was 

not subject to the rigorous external review by senior experts that is 

often conducted for similar life-safety structures and systems.

The first of ASCE’s Fundamental Canons in its Code of Ethics states, 

“Engineers shall hold paramount the safety, health and welfare of the public....” 

Serious deficiencies in the southeast Louisiana hurricane protection system 

must be corrected if the New Orleans area is to avoid a similar catastrophe 

when the next major hurricane strikes. 

The ASCE Hurricane Katrina External Review Panel strongly urges 

that organizations responsible for critical life-safety facilities be organized 

and operated to enable, not to inhibit, a focus on safety, and that engineers 

continually evaluate the appropriateness of design criteria, always considering 

how the performance of individual components affects the overall performance 

of a system. Specific recommendations include:

• Keep safety at the forefront of public priorities by having all 

responsible agencies re-evaluate their policies and practices to 

ensure that protection of public safety, health, and welfare is the 

top priority for infrequent but potentially devastating impacts from 

hurricanes and flooding. Also, encourage Congress to establish and 

fund a mechanism for a nationwide levee safety program, similar 

to that which is in place for dams.

• Quantify and periodically update the assessment of risk. This 

approach should be extended to all areas in the United States that 

are vulnerable to major losses from hurricanes and flooding.

• Determine the level of acceptable risk in the community through 

quality interactive public risk communication programs in New 
viii THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why

Orleans and other areas threatened by hurricanes and flooding. 

Once determined, manage the risks accordingly.

• Correct the system’s deficiencies by establishing mechanisms to 

incorporate changing information, making the levees survivable if 

overtopped, strengthening the I-walls and levees, and upgrading 

the pumping stations.

• Assign to a single entity or individual (a licensed engineer) the 

responsibility of managing critical hurricane and flood protection 

systems such as the one in New Orleans.

• Implement more effective mechanisms for coordination and 

cooperation. (For example, those responsible for maintenance of 

the system must collaborate with system designers and must 

upgrade their inspection, repair, and operations processes to 

ensure that the system is hurricane- and flood-ready.)

• Upgrade engineering design procedures and practice to place 

greater emphasis on safety.

• Engage independent experts in high-level reviews of all critical lifesafety structures, including hurricane and flood-protection systems.

In a very real sense, the findings and conclusions in this report extend 

far beyond the New Orleans hurricane protection system. The lessons learned 

from the engineering and engineering-related policy failures triggered by 

Hurricane Katrina have profound implications for other American communities 

and a sobering message to people nationwide: we must place the protection 

of safety, health, and welfare at the forefront of our nation’s priorities. To 

do anything less could lead to a far greater tragedy than the one witnessed in 

New Orleans. 
1

C H A P T E R 1

Introduction

On the morning of August 29, 2005, Hurricane Katrina struck southeast 

Louisiana and triggered what would become one of the worst disasters 

ever to befall an American city. The storm overtopped levees and floodwalls 

throughout southeast Louisiana and also caused the levees and floodwalls in 

the New Orleans area to fail or breach in more than 50 locations. Water rushed 

into New Orleans and flooded over 80 percent of the city—more than 10 feet 

deep in some neighborhoods. 

One thousand one hundred eighteen (1,118) people lost their lives in 

the New Orleans area, and 135 more are still missing and presumed dead. 

Tens of billions of dollars worth of property was damaged. More than 400,000 

people fled the city. Many have not returned. The educational and health care 

systems of the New Orleans area have been crippled. The devastation was so 

extensive, and the residual risk looms so ominous, that, more than a year and 

a half later, the future of New Orleans remains clouded.

The members of the American Society of Civil Engineers (ASCE) 

extend their sincere condolences to the families and friends of those who 

lost their lives during and after Hurricane Katrina. Our heartfelt sympathy 

goes out to the people of the New Orleans area who are left without homes, 

communities, and jobs, and to those who face an uncertain future.

The members of the ASCE Hurricane Katrina External Review Panel 

have conducted an in-depth review of the comprehensive work of the United 

States Army Corps of Engineers (USACE) Interagency Performance Evaluation 

Taskforce (IPET). We are indebted to the dedicated efforts of more than 150 

engineers and scientists who have, in the year and a half following Hurricane 

Katrina, evaluated the causes of the New Orleans area hurricane protection 

system failures. 

As a result of this excellent work, we now better understand what 

went wrong and why. The ASCE Hurricane Katrina External Review Panel has 

an obligation to share its findings and insights, which go beyond the scope 

of the IPET review, so that others may learn from this tragedy and prevent 

similar disasters from happening again, not only in New Orleans, but in 

other communities throughout the United States that are also vulnerable to 

hurricanes and flooding.
2 THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why

Interagency Performance Evaluation Taskforce

In the aftermath of the storm and flooding, Lieutenant General Carl A. Strock, 

P.E., Chief of Engineers, USACE, ordered an investigation to provide credible, 

objective engineering and scientific answers to fundamental questions about 

the operation and performance of the hurricane protection system in southeast 

Louisiana. The results of the performance evaluation were intended to answer 

the following four questions: 

1. What were the storm surges and waves generated by Hurricane Katrina 

and did overtopping occur?

2. How did the floodwalls, levees, and drainage canals, acting as an integrated 

system, perform and breach during and after Hurricane Katrina?

3. How did the pumping stations, canal gates, and road closures, acting as 

an integrated system, operate in preventing and evacuating the flooding 

due to Hurricane Katrina?

4. What was and what is the condition of the hurricane protection system 

before and after Hurricane Katrina and, as a result, is the New Orleans 

protection system more susceptible to flooding from future hurricanes 

and tropical storms?

The objectives of the IPET work included identifying lessons learned 

and ways to potentially improve the performance of the existing hurricane 

protection system at the authorized level of protection. The IPET’s work is 

documented in a comprehensive final report that is available at https://ipet.

wes.army.mil/.

ASCE’s Hurricane Katrina External Review Panel

The Chief of Engineers requested that ASCE form an external review panel to 

review and comment on IPET’s work. ASCE brought together 14 experts in the 

key engineering and scientific disciplines related to the hurricane protection 

system failure to form the ASCE Hurricane Katrina External Review Panel. 

The ASCE Hurricane Katrina External Review Panel’s scope of work 

was to provide an ongoing, real-time, and objective technical review of the 

IPET report findings on the performance of the hurricane protection system in 

New Orleans and surrounding areas. ASCE Hurricane Katrina External Review 

Panel members visited New Orleans, examined the damaged areas, and had 

access to large amounts of information about the catastrophe and its causes. 

Beginning with the formulation of IPET’s scope of work, the ASCE Hurricane 

Katrina External Review Panel members have been in close contact with IPET 

investigators, have actively submitted informal comments to the IPET, and 

have reviewed each IPET report in detail.
THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why 3

The factual and technical foundation for the findings presented in this 

report is the extensive work by IPET, although this report also draws from 

ideas expressed by others. Even though IPET’s work formed the basis of the 

technical analysis, this report was prepared independently of IPET and the 

USACE, and solely reflects the views of the ASCE Hurricane Katrina External 

Review Panel members. 

Other Teams of Investigators

Among the first groups of engineers to visit New Orleans after Hurricane 

Katrina was a levee assessment team from ASCE. This team examined and 

documented post-flood conditions to aid in investigating the causes of the 

failure. The results are presented in Report No. UCB/CITRIS–05/01, “Preliminary 

Report on the Performance of the New Orleans Levee Systems in Hurricane 

Katrina on August 29, 2005,” November 17, 2005. Two of the members of the 

ASCE levee assessment team are members of the ASCE Hurricane Katrina 

External Review Panel.

The National Research Council of the National Academies performed 

a review of both IPET’s and the ASCE Hurricane Katrina External Review 

Panel’s work under NRC/NAE project DEPS-L-05-02-A, “New Orleans Regional 

Hurricane Protection Projects.” The scope of the National Academies review 

was: 

1. Review the data gathered by the IPET and the ASCE teams and provide 

recommendations regarding the adequacy of those data, as well as 

additional data that will be important to the IPET study and which should 

be gathered. 

2. Review the analyses performed by the IPET and ASCE to ensure their 

consistency with accepted engineering approaches and practices.

3. Review and comment upon the conclusions reached by the IPET and ASCE 

teams, and; 

4. Seek to determine lessons learned from the Katrina experience and 

identify ways that hurricane protection system performance can be 

improved in the future at the authorized level of protection.

This Report

Through this report, the ASCE Hurricane Katrina External Review Panel offers 

an assessment of what happened to the New Orleans hurricane protection 

system as a result of Hurricane Katrina—and why it happened. This report 

focuses on the direct physical causes and contributing factors to the hurricane 

protection system failures. This report was developed not to repeat the IPET 

information but, rather, to interpret the broader significance of the findings. In 

the broadest sense, the lessons learned from this catastrophe are not limited to 
4 THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why

New Orleans or to levees and floodwalls: they are applicable to all engineering 

projects where public health, safety, and welfare are at risk. Issues pertaining 

to pre- or post-hurricane evacuation, rescue operations, or recovery efforts 

were not part of the scope of this study, although all of these issues have 

an impact on the ultimate consequences of the hurricane protection system 

failures. 

The report is written for both the scientist/engineer and the layperson. 

The scientist/engineer will glean valuable information related to the science 

and technology of hurricane flood protection. The layperson will gain a broad 

understanding of exactly what caused the disaster.

Perhaps the most difficult question is not so much “What went wrong 

and why?” but “What must we do next?” to avoid a similar catastrophe in the 

future—in New Orleans and in other hurricane- and flood-prone areas of the 

country. The ASCE Hurricane Katrina External Review Panel believes strongly 

that if lives and public safety are to be protected, significant changes will 

be required in the way hurricane and flood protection systems are funded, 

designed, managed, and maintained.
5

C H A P T E R 2

New Orleans

New Orleans is located in southeastern Louisiana near where the Mississippi 

River flows into the Gulf of Mexico (Figure 2.1). The busy Port of New Orleans 

provides a gateway for imports including petroleum, steel, copper, rubber, 

cement, coffee, and containerized goods. The chief exports are grain and other 

foods from the midwestern United States and petroleum products. Thousands 

of ocean vessels from Europe, Asia, Latin America, and Africa move through 

New Orleans on the Mississippi River every year.

Figure 2.1 Satellite Photo of New Orleans Area

New Orleans, Louisiana, located near where the Mississippi River flows into the Gulf of 

Mexico, is one of the nation’s most important ports. 

From New Orleans, products reach Americans either via a 14,500-

mile inland waterways network including the Mississippi, Missouri, and Ohio 

Rivers, or via other transportation modes, including six railroad lines, 50 ocean 

carriers, 16 barge lines, and 75 truck lines with access to the port. In addition 

to cargo, cruise ships and riverboats transport more than 700,000 passengers 

through the port annually. 

New Orleans is a part of Louisiana’s extensive petroleum infrastructure 

that provides oil and other petroleum products to the nation. Louisiana ranks 

fifth in United States oil production, and is home to a network of pipelines 

and storage facilities plus 17 petroleum refineries, as well as to two of the 

nation’s four Strategic Petroleum Reserves, which encompass the world’s 

largest business center supply of emergency crude oil (Figure 2.2). New 

Orleans also serves as a business center for energy companies such as BP, 

Shell Oil, Chevron, and ConocoPhillips.
6 THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why

Figure 2.2 Flooded Petroleum Storage Tank Farm

New Orleans is a major hub of regional petroleum production and refining operations 

providing up to 30 percent of the nation’s oil. Damage to the petroleum complex from 

Hurricane Katrina was extensive. 

A City on the River

Over the millennia, the Mississippi River has carried billions of tons of sediment 

from its headwaters toward the Gulf of Mexico. As the water flowed into 

the gulf, the sediment was deposited in the river delta, creating the land on 

which New Orleans and surrounding areas is now built. Within the river delta, 

high ground tends to be close to the Mississippi River due to natural river 

processes. New Orleans was established in the early 1700s on high ground 

adjacent to the Mississippi River. 

When floods occur on a major river, water mixed with sediment spills 

over the banks. The coarsest sediments (sand and gravel) settle out first, 

close to the river, forming natural levees near the river banks. Fine sediments 

(silt and clay) settle out further away into the swampland. 

Over many floods and many alterations in the course of the river 

channel, this natural process has created a complex, highly variable geology. 

Layers of gravel, sand, silt, and clay are inter-fingered with layers of organic 

marsh deposits (often called peat) at various locations. 
THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why 7

Development on the Marshes

A map of the east bank of New Orleans from 1849 (Figure 2.3) shows 

developed areas adjacent to the river, with cypress swamps, marshes, and 

bayous flanking the city to the north and east. The bayous naturally flowed 

northward into Lake Pontchartrain and eastward into Lake Borgne; Lake Borgne 

opens directly to the Gulf of Mexico. As New Orleans grew and prospered, 

levee systems were built around segments of the low swamplands to the 

north of the city, and the land was drained and developed.

Figure 2.3 New Orleans in 1849

An 1849 map shows New Orleans built adjacent to the Mississippi River, with marshlands 

and bayous to the north. 

The parishes of New Orleans and the neighborhoods within the 

parishes are shown in Figure 2.4. (Parishes are equivalent to counties in 

other parts of the United States.) Of primary significance to this report are 

Orleans and St. Bernard parishes. Significant flooding occurred in both due to 

failures in New Orleans’s hurricane protection system.
8 THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why

Figure 2.4 The Parishes and Neighborhoods of New Orleans

St. Bernard, Plaquemines, and Orleans parishes were the most affected by flooding after 

Hurricane Katrina.

Levees and floodwalls were also built on the banks of several of the 

former bayous from Lake Pontchartrain into New Orleans. Waterways of 

significance to this report (as shown in Figure 2.5) include:

• 17th Street Canal 

• Orleans Canal

• London Avenue Canal

• Inner Harbor Navigation Canal (also called the Industrial Canal)

• Gulf Intracoastal Waterway

• Mississippi River Gulf Outlet

New Orleans is Sinking

Large portions of Orleans, St. Bernard, and Jefferson parishes are currently 

below sea level—and continue to sink. New Orleans is built on thousands of 

feet of soft sand, silt, and clay. Subsidence, or settling of the ground surface, 

occurs naturally due to the consolidation and oxidation of organic soils (called 

“marsh” in New Orleans) and local groundwater pumping. In the past, flooding 

and deposition of sediments from the Mississippi River counterbalanced the 

natural subsidence, leaving southeast Louisiana at or above sea level. 

However, due to major flood control structures being built upstream 

on the Mississippi River and levees being built around New Orleans, fresh 

layers of sediment are not replenishing the ground lost by subsidence. The 

natural subsidence has also been exacerbated by groundwater withdrawals, 

petroleum production, development, and other factors. Based on data 

collected by the United States Geological Survey from benchmarks located 

primarily in Orleans Parish (1951-1995), subsidence has been estimated to 

occur at an average rate of about 0.15 to 0.2 inches per year, although rates in 

excess of 1 inch per year occur in some locations. 
THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why 9

Figure 2.5 The New Orleans Waterways

New Orleans is surrounded by – and inter-fingered with – water: lakes, rivers, bayous, 

and canals.

The People of New Orleans

According to the 2004 United States Census, the population of the greater 

New Orleans metropolitan area affected most by Hurricane Katrina was 

approximately one million—67 percent African American, 28 percent 

Caucasian, and small percentages of Hispanics and Asians (3 percent and 2 

percent, respectively). Studies attempting to estimate the city’s post-Katrina 

population have set the 2006 population at around 580,000—a 44 percent 

decrease (Figure 2.6).

Figure 2.6 Population of the New Orleans Region

The combined populations of Jefferson, Orleans, St. Bernard, and Plaquemines parishes 

dropped by 44 percent after Hurricane Katrina. Orleans Parish’s population dropped 63 

percent.
10 THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why

A Cultural Treasure

New Orleans fell under French, Spanish, and—following the Louisiana 

Purchase—American control, all within 100 years. Influences from the ruling 

nations blended with contributions from others entering the port city: African 

slaves, Caribbean islanders, and several waves of Italians, Germans, and Irish 

fleeing famine or simply seeking a new life in America. As a result, celebrations 

of Mardi Gras, St. Patrick’s Day, St. Joseph’s Day, and voodoo rituals all find a 

welcome home in New Orleans. The blend of languages also created words 

and phrases unheard in any other part of the country.

Some of the nation’s oldest and most historic structures are located in 

New Orleans. Lacy ironwork and French- and Spanish-style architecture lend 

the city a European flavor. New Orleans’s most famous export, jazz, also grew 

out of the city’s mesh of cultures as European music styles gradually fused 

with ragtime, blues, and gospel (Figure 2.7).

Creole cuisine, essentially classic French cooking incorporating local 

ingredients, is served in homes and restaurants, as is Cajun food, which was 

introduced to New Orleans by French-Canadian settlers in Louisiana.

 Figure 2.7 A New Orleanian Leaving the City after the Hurricane

New Orleans is one of the most culturally rich and diverse cities in the U.S. in terms of 

music, architecture, food, and language. New Orleans is the home of jazz, America’s most 

widely recognized indigenous musical art form.
11

C H A P T E R 3

Hurricane Katrina

Hurricane Katrina was one of the strongest storms ever to hit the coast of the 

United States; New Orleans was directly in Hurricane Katrina’s path. Hurricane 

Katrina brought intense winds, rainfall, waves, and storm surges that caused 

widespread devastation in New Orleans and along the coasts of Louisiana, 

Mississippi, and Alabama.

Hurricanes are not new to the Gulf Coast. Major hurricanes to have hit 

the Gulf Coast in the vicinity of southeast Louisiana are listed in Table 3.1:

Table 3.1 Major Hurricanes to Have Crossed Southeast Louisiana or Vicinity (1851-2004)

Source: National Oceanic and Atmospheric Administration (NOAA) Technical 

Memorandum NWS TPC-4, “The Deadliest, Costliest, and Most Intense United States 

Tropical Cyclones from 1851 to 2005 (and Other Frequently Requested Hurricane Facts)”

*Hurricane Andrew was a Category 5 hurricane in Florida but a Category 3 hurricane as it 

reached Louisiana.

The Storm

Hurricanes are intense low-pressure areas that form over warm ocean waters 

in the summer and early fall. As warm, moist air rises from the ocean surface 

into cooler air above, the water vapor condenses to form droplets and clouds. 

This condensation releases heat, boosting the rise of the air, lowering the 

central pressure, and drawing more warm, moist air into the storm. In this 

manner, the energy builds up and the wind speed increases. The low pressure 

causes wind to spiral inward toward the center of the low-pressure area, 

creating the hurricane. In the northern hemisphere, hurricane wind rotation 

HURRICANE YEAR CATEGORY AT 

FIRST LANDFALL

CENTRAL PRESSURE 

AT FIRST LANDFALL

(millibars)

Camille 1969 5 909

Katrina 2005 3 920

Andrew 1992 5* 922

LA (New Orleans) 1915 4 931

LA (Last Island) 1856 4 934

SE FL/SE LA/MS 1947 4 940

Audrey 1957 4 945

LA (Chenier Caminanda) 1893 3 948

Betsy (SE FL/SE LA) 1965 3 948

LA/MS 1855 3 950

LA/MS/AL 1860 3 950

LA 1879 3 950

LA (Grand Isle) 1909 3 952
12 THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why

around the eye of a hurricane is counter-clockwise. Hurricanes are categorized 

based on maximum wind speed according to the Saffir-Simpson Hurricane 

Scale, as summarized in Table 3.2. 

Table 3.2 The Saffir-Simpson Hurricane Scale 

The path of and intensity history of Hurricane Katrina are shown in 

Figure 3.1. The storm started as a tropical depression in the Bahamas on 

August 23, 2005. It crossed south Florida on August 25 as a Category 1 

hurricane, and then entered the Gulf of Mexico. The storm intensified as it 

tracked westward. 

Figure 3.1 Path and Intensity History of Hurricane Katrina

This image is a montage of four satellite photographs taken in late August 2005, as Hurricane 

Katrina made its way from the Bahamas through the Gulf of Mexico, gaining strength. 

CATEGORY WIND SPEED 

(mph)

TYPICAL STORM 

WATER SURGE (ft)

1 74 - 95 4 - 5

2 96 - 110 6 - 8

3 111 - 130 9 - 12

4 131 - 155 13 - 18

5 > 155 > 18
THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why 13

On August 28, the storm began tracking toward the northwest, and 

intensified from a Category 2 to a Category 5 storm in just 12 hours. As it 

approached land, the warm, moist air and energy that Hurricane Katrina could 

draw from the Gulf of Mexico decreased, and Hurricane Katrina was degraded 

to a Category 3 storm. The path of the storm as it crossed into Louisiana is 

shown in Figure 3.2. 

Figure 3.2 Traced Path of Hurricane Katrina over New Orleans

The eye of Hurricane Katrina tracked nearly due north across southern Louisiana, about 

30 miles east of downtown New Orleans. 

Wind, Water, and Waves

The strong wind and low atmospheric pressure of a hurricane causes storm 

surges. Storm surges typically cause the most damage near the coast, whereas 

winds cause the most damage away from the coast. Three factors contribute 

to the formation and intensity of a storm surge:

1. Wind-induced motion of water. The wind drags along the ocean’s surface 

and causes the water to pile up as a surge higher than tide level. This is 

the main contributor to high water from a major hurricane. As the water 

and waves reach the shore, flooding typically occurs. Wind also generates 

waves on the water’s surface, increasing the momentum of the surge 

toward land and adding to the water height on top of the surge. As Katrina 

crossed the Gulf, easterly winds blowing for several days caused water to 
14 THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why

pile up against the east bank of the Mississippi River that juts out into the 

Gulf.

2. Reduced pressure from the storm. Atmospheric pressure is roughly 

30 inches of mercury. Hurricane Katrina had a minimum central pressure 

of about 27 inches, or 3 inches below atmospheric pressure. Typically, 

water will rise about 1 foot of water for every inch drop of mercury. 

Therefore, sea level was about 3 feet above normal because of the low 

pressures of Hurricane Katrina.

3. Favorable or unfavorable timing with high and low ocean tides. The 

worst combination is when a hurricane-induced storm surge occurs during 

high tide which was, indeed, the case when Hurricane Katrina hit land. 

A satellite view of Hurricane Katrina taken at 10:15am on August 29, 

2005 is shown in Figure 3.3. At its peak strength about 200 miles off the 

Louisiana coast (24 hours prior to landfall), Hurricane Katrina generated winds 

with speeds of up to 160 miles per hour (mph) (1-minute average). Hurricane 

Katrina also reached a minimum central pressure of 902 millibars (27 inches 

of mercury) at its peak, ranking fourth lowest on record for all Atlantic basin 

hurricanes, and produced offshore individual waves approximately 100 feet 

high in the Gulf of Mexico, which are some of the largest waves for any 

hurricane over the past century. 

Figure 3.3 The Eye of Hurricane Katrina as seen from a NOAA Satellite 

Hurricane Katrina was one of the strongest storms to hit the coast of the United States. 

The eye of Hurricane Katrina is shown in the center of the photo. The maximum wind 

speeds estimated during Hurricane Katrina were 160 miles per hour. 
THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why 15

The leading edge of Hurricane Katrina made landfall at Buras, 

Louisiana, at 6:10am, August 29, 2005. The central pressure at landfall was 

920 millibars, which ranked third lowest on record for United States landfalling storms. Although Katrina struck Louisiana as a Category 3 storm, its 

earlier status as a massive Category 5 storm added to the magnitude of the 

storm surge as Katrina approached the coast with ever greater intensity. 

When the eye of Hurricane Katrina struck at Buras at 6:30am, winds were 

approximately 127 mph.

Figure 3.4 shows wind vectors and storm surge elevation at about 

7:30am on August 29, when the eye of the storm was just southeast of 

downtown New Orleans. The eastern edge of the New Orleans area was 

pounded by wind and water from the east. The northern edge of the New 

Orleans area along Lake Pontchartrain was pounded by wind and waves from 

the north. An enormous storm surge of water from the Gulf of Mexico built 

up in Lake Borgne. 

The Mississippi River delta, which juts out to the southeast of New 

Orleans, created a barrier of land just to the west of the eye against which the 

massive storm surge also piled up. In south Plaquemines Parish, peak water 

levels reached 20 feet above mean sea level along the hurricane protection 

levees. 

Figure 3.4 Wind Vectors and Calculated Storm Surge about 7:30am on August 29, 2005 

New Orleans was pounded by wind and water on the north and east. Wind drove water 

from the Gulf of Mexico into Lake Borgne. Water from Lake Pontchartrain was driven 

against New Orleans’s lakeshore by winds blowing from the north. 
16 THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why

The wind on Lake Pontchartrain was out of the north, piling up water 

along the southern shore of the lake. Peak water levels at the entrances to 

canals along the lakeshore of New Orleans were nearly 12 feet above sea 

level. 

During a storm surge, the water level rises significantly above tide 

level for a few hours. After the hurricane passes and the direction of the wind 

shifts, water levels recede. A hydrograph, a graph of water level versus time, 

for the canal entrances at Lake Pontchartrain is shown in Figure 3.5. The 

highest water level occurred at approximately 9:30am on August 29, after 

which the water levels fell. 

Figure 3.5 Hydrograph for the Canal Entrances at Lake Pontchartrain 

On the lakeshore of New Orleans, water levels from the storm surge built up to a peak at 

9:30am By 10:00am, the eye of the hurricane had passed slightly to the northeast of New 

Orleans, and the water levels began to fall. 

In addition to the storm surges, Hurricane Katrina brought intense 

rainfall to the New Orleans area. Within Orleans Parish, for example, estimates 

of precipitation based on radar rainfall data indicate that up to 13.6 inches fell 

in some areas over the 24-hour period encompassing Hurricane Katrina. The 

100-year rainfall (24-hour duration) for New Orleans is 12.58 inches, based on 

United States Weather Bureau Technical Paper 40 (1961). This means that 

there is a 1 in 100 probability in any given year that there will be 24-hour 

period where the accumulated rainfall will be greater than 12.58 inches.
17

C H A P T E R 4

 Hurricane Protection System

The USACE is responsible for the design and construction of most of the flood 

and hurricane protection levees along the Mississippi River and in the New 

Orleans area. Congress authorized the first major project to address hurricaneinduced flooding in 1946. Since that time, as New Orleans’s infrastructure 

and population has expanded, Congress has authorized a number of additional 

hurricane protection projects. 

In addition, there are several other flood protection systems in and around 

New Orleans that are owned or operated by other agencies. These include:

• Interior drainage and pumping stations

• The Mississippi River Levee Flood Protection System

• Non-USACE levee features

The USACE’s overall strategy to protect against flooding caused by 

hurricanes and storm surge was to build levees or floodwalls around segments 

of New Orleans. The USACE projects are generally grouped into three main 

units, as shown in Figure 4.1: 

• Lake Pontchartrain, Louisiana and Vicinity Hurricane Protection 

Project

• West Bank and Vicinity, New Orleans, Louisiana, Hurricane 

Protection Project

• New Orleans to Venice, Louisiana, Hurricane Protection Project

Figure 4.1 Three USACE Hurricane Protection Systems in Southeast Louisiana

Over the past several decades, the USACE has designed and built three main hurricane 

protection systems to protect New Orleans and surrounding parishes from hurricaneinduced flooding. The USACE designed and built the majority of the levees and floodwalls 

but they are maintained by local levee boards. Other levees and floodwalls are owned and 

operated by local levee boards. All of the pump stations are owned and operated by local 

agencies. 
18 THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why

The Lake Pontchartrain, Louisiana and Vicinity Hurricane Protection 

Project (Figure 4.2) was intended to protect St. Bernard, Orleans, Jefferson, 

and St. Charles parishes between the Mississippi River and Lake Pontchartrain. 

The project generally included earthen levees with floodwalls along Lake 

Pontchartrain, the 17th Street Canal, the Orleans Canal, the London Avenue 

Canal, and the Industrial Canal. 

Figure 4.2 Lake Pontchartrain, Louisiana and Vicinity Hurricane Protection Project

Failures within this hurricane protection system, comprised of earthen levees and 

floodwalls, caused the majority of the widespread flooding and damage during and after 

Hurricane Katrina.

The West Bank and Vicinity, New Orleans, Louisiana, Hurricane 

Protection System (Figure 4.3) was intended to provide improved hurricane 

protection and flood control to portions of Jefferson Parish lying between 

the Mississippi River and Lake Salvador. The recommended plan included 22 

miles of earthen levees and 2 miles of floodwalls extending from the canal to 

the V-levee near Jean Lafitte National Historical Park back north to the town 

of Westwego.

The New Orleans to Venice, Louisiana, Hurricane Protection Project is 

located along the east bank of the Mississippi River from Phoenix, Louisiana, 

(approximately 28 miles southeast of New Orleans) down to Bohemia, 

Louisiana, and along the west bank of the river from St. Jude, Louisiana, 

(approximately 39 miles southeast of New Orleans) down to the vicinity of 

Venice, Louisiana. As shown in Figure 4.4, the project generally consisted of 

earthen levees built along the Mississippi River. 
THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why 19

Figure 4.3 West Bank and Vicinity, New Orleans, Louisiana, Hurricane Protection System

This hurricane protection system consists of earthen levees and floodwalls in New 

Orleans on the west bank of the Mississippi River. 

Figure 4.4 New Orleans to Venice, Louisiana, Hurricane Protection Project 

This hurricane protection system is intended to protect the low-lying land between the 

Mississippi River and the Gulf of Mexico from storm surge.
20 THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why

Standard Project Hurricane

The United States Congress directed the USACE to design the hurricane 

protection system for “the most severe combination of meteorological 

conditions that are considered ‘reasonably characteristic’ of the region.” The 

approach historically taken by the USACE for design of Gulf Coast structures 

employs the concept of the “standard project hurricane,” or SPH. 

Following Hurricane Betsy in 1965, the USACE’s selection of sitespecific storm meteorological criteria was guided by the 1959 National 

Hurricane Research Project Report 33, “Meteorological Considerations 

Pertinent to Standard Project Hurricane, Atlantic and Gulf Coasts of the 

United States.” In Project Report 33, the United States Weather Bureau (now 

the National Weather Service) recommended a single value for the central 

pressure index, three values each for forward speed and radius to maximum 

wind, one gradient wind speed value, and two values of surface wind speed. 

These criteria were based on historic hurricanes from 1900 to 1956.

In memoranda issued in 1959 and 1961, the USWB defined a probable 

maximum hurricane (PMH) as one that may be expected from the most 

severe combination of critical meteorological conditions that are “reasonably 

possible” for the region. The PMH had a lower central pressure index than 

the SPH. 

At the outset of each hurricane protection project, the USACE chose 

design meteorological conditions that comprised the SPH based on the USWB 

recommendations. Facilities and structures were then designed to withstand 

the impacts of the SPH. The SPH meteorological criteria from Project Report 

33 were used to design the Lake Pontchartrain and Vicinity and the New 

Orleans to Venice Hurricane Protection Projects.

In 1979, NOAA issued Technical Report NWS 23, “Meteorological 

Criteria for Standard Project Hurricane and Probable Maximum Hurricane 

Windfields, Gulf and East Coasts of the United States.” This report contained 

revised criteria for the SPH, incorporating the characteristics of more recent 

hurricanes, including Hurricane Betsy, which directly hit New Orleans. Report 

NWS 23 also contained revised criteria for the PMH. 

The West Bank and Vicinity Hurricane Protection Project was designed 

and constructed after Report NWS 23 was issued. It does not appear that the 

USACE used the updated SPH criteria, however. 

Levees and Floodwalls

The USACE designed and built three types of flood protection structures in 

New Orleans’s hurricane protection system, as shown in Figure 4.5. Earthen 

levees comprised the majority of the system. 
THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why 21

Figure 4.5 Typical USACE Flood Protection Structures 

The USACE’s levees and floodwalls followed a standard design, although the height of 

levees and walls varied throughout the hurricane protection system. In some places, 

hydraulic fill was used instead of compacted material to construct levees.

When an earthen levee is raised with additional earth fill, it can 

typically only be heightened by increasing the width at the base, as shown in 

Figure 4.6. In most urban areas of New Orleans, the land has been developed 

right up to the base of the levee. To raise and widen the levee would require 

private property to be purchased and buildings to be removed. Local opposition 

to such use of land is almost always considerable. A floodwall constructed in 

an existing levee allows the height of the levee to be raised without requiring 

the taking of adjacent property for levee expansion.

Figure 4.6 Increasing the Top Elevation of an Earthen Levee 

Raising the top elevation of an existing earthen levee with additional earth fill also 

involves increasing its width. Where an existing levee was located adjacent to buildings, 

canals, or other structures, the USACE often resorted to using I-walls to avoid impacting 

adjacent development. 
22 THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why

Some levee segments—particularly at gated closure structures where 

the levee alignment crosses roads or railroads—were constructed of T-walls 

instead of I-walls. T-walls are concrete structures shaped like an inverted T, 

supported on pre-cast pre-stressed concrete piles or steel H piles. Although 

T-walls are more robust than I-walls, they also cost much more to construct.

Datums and Elevations 

The USACE authorized, designed, and modeled flood control structures in 

southeast Louisiana relative to a water level reference datum (e.g., Mean Sea 

Level (MSL); local MSL). MSL was assigned an elevation of zero. However, the 

structures were constructed relative to a geodetic (land-based) vertical datum 

that was incorrectly assumed as being equivalent to, or constantly offset 

from, the water level datum. This resulted, in the case of the outfall canals, in 

structures built approximately 1 to 2 feet below the intended elevation.

Each of the hurricane protection projects was designed and 

constructed on a project-by-project basis over the course of many years as 

funding became available. At the time of Hurricane Katrina, segments of the 

levee system were not yet complete, or the top elevations had not been 

raised to the authorized protective levels. Furthermore, because of regional 

subsidence, the hurricane protection structures had subsided as well, so that 

their top elevations were lower than originally designed or constructed. The 

Industrial Canal structures, for example, are more than 2 feet below their 

intended design elevations, mostly from subsidence over the 35-year life of 

the project.

Interior Drainage and Pump Stations

The average annual rainfall for the New Orleans area is 60 inches. Because 

much of New Orleans is below sea level (in effect, a series of large “bowls” 

surrounded by levees), nearly all runoff must be pumped out to prevent 

flooding. The interior drainage system was designed to remove stormwater 

runoff from rainfall events, not to remove water that enters the area from 

levee or floodwall overtopping or breaches. 

New Orleans’s interior drainage system consists of overland flow, 

storm sewers, roadside ditches, collector ditches, interior canals, interior 

pump (lift) stations, outfall pump stations, and outfall canals -- all designed 

to work together to gather runoff and then pump it into Lake Pontchartrain, 

Lake Borgne, or other nearby bodies of water. In Orleans Parish, this water 

is pumped out via major canals such as the 17th Street, Orleans, and London 

Avenue Canals. In a few locations, the pump stations discharge directly into 

the Industrial Canal and Intracoastal Waterway.
THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why 23

New Orleans’s pumping system is one of the largest in the world. 

There are nearly 100 pumping stations in the greater New Orleans area. Some 

have been recently completed; others are approaching 100 years of age. Most 

of the pump stations appear to have been designed to handle flows from a 

10-year, 24-hour storm, or around 9 inches of rainfall. For purposes of pump 

station design, each of the four parishes in the New Orleans area was divided 

into drainage subbasins. The basins usually follow natural topographical lines. 

They are often bordered by levees or ridges of relatively higher elevation. 

Operational power is provided by various means. Some stations use 

pumps directly connected to diesel engines. For many stations, power is 

normally provided by the electrical grid, with back-up diesel generators or 

direct-drive diesel engines available when the electrical grid is out of service. 

Some of the older stations use 25 Hertz (Hz) power provided by a central 

generating plant to run the pumps. These stations use frequency changers to 

change 25 Hz power to 60 Hz power for the operation of their station service 

system.
24 THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why
25

C H A P T E R 5

 The Levees Fail

The Lake Pontchartrain and Vicinity Hurricane Protection Project system 

experienced the worst damage during and after Hurricane Katrina and resulted 

in the most serious consequences to the city and people of New Orleans. 

The massive, destructive flooding of New Orleans was caused by ruptures 

at approximately 50 locations in the city’s hurricane protection system. Of 

the 284 miles of federal levees and floodwalls—there are approximately 350 

miles in total—169 miles were damaged. 

Levees in the USACE’s New Orleans to Venice Hurricane Protection 

Project sustained significant damage caused by powerful flood waters 

overtopping and breaching the levees. 

The levees in the USACE’s West Bank and Vicinity Hurricane Protection 

Project experienced the least amount of damage. 

Storm Surge Damage

Even before Hurricane Katrina made landfall, storm surge energized by the 

storm’s outer bands began to creep into low-lying areas around Lake Borgne. 

Before dawn on August 29, rising water levels reached the Industrial Canal. 

Waves, in conjunction with high storm surge, overtopped and eroded the 

Mississippi River-Gulf Outlet levees (Figure 5.1) and flooded portions of St. 

Bernard Parish.

Figure 5.1 Storm Surge under the Paris Road Bridge in New Orleans East

Entergy Corporation personnel took this photo of storm surge waters cascading over a 

levee near the Entergy power plant in the New Orleans East area. 
26 THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why

At 6:10am, Hurricane Katrina made landfall at Buras, east of New 

Orleans, and storm surge flooded most of Plaquemines Parish (Figure 5.2). 

Strong east-west winds built up a significant surge level at the Intracoastal 

Waterway. By 6:30am, levees lining the south side of the New Orleans East 

neighborhood were overtopped and breached, flooding the area. Within an 

hour of the hurricane’s landfall, wind-generated waves reached heights of at 

least 4 feet in the Industrial Canal, causing overtopping into portions of the 

Gentilly and Bywater neighborhoods.

Figure 5.2 Hurricane Damage in Plaquemines Parish

The storm surge from Hurricane Katrina overtopped levees (seen in this photo adjacent to 

the water) in Plaquemines Parish and knocked hundreds of homes off their foundations. 

(This photo was taken after flood waters had receded.)
THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why 27

Cracks in the System

Before and during Hurricane Katrina’s landfall, ruptures (or breaches) in four 

I-walls developed (Figure 5.3)—all before water levels in the adjacent canals 

overtopped them . 

Figure 5.3 Major Breaches in the New Orleans Hurricane Protection System

Failures of several I-walls and levees along the canals that finger into New Orleans 

allowed massive amounts of water to flood New Orleans. 

At about 5am, a breach in the east bank of the Industrial Canal 

I-wall contributed the first flow of floodwaters to the Lower Ninth Ward in 

St. Bernard Parish. At about 6:30am, a breach was observed in the I-wall on 

the Orleans Parish side of the 17th Street Canal, which flooded a portion of 

Lakeview.

At about 7:00am, a breach occurred in a London Avenue Canal I-wall 

near Mirabeau Avenue in Gentilly (South Breach). About an hour later, a second 

breach occurred on the London Avenue Canal near Robert E. Lee Boulevard 

(North Breach). 
28 THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why

Flooding Ensues

Within a few hours of the initial breach observed at the Industrial Canal, rising 

water in the canal overtopped and eroded levees. Torrents of water rushed 

into city streets. Multiple levee failures inundated some neighborhoods from 

several sides with such speed that houses filled to their rooftops in minutes 

(Figure 5.4). In other areas, the rise of water was slower, but constant, filling 

homes at a rate of 1 foot every 10 minutes. On the west side of the Industrial 

Canal, I-wall failures allowed water to flood into the Upper Ninth Ward, 

Bywater, and Tremé neighborhoods. Another large floodwall breach on the 

east side of the Industrial Canal quickly flooded the Lower Ninth Ward in what 

witnesses describe as a “wall of water.” Floodwaters from this break (shown 

in Figure 5.5) reached other neighborhoods of St. Bernard Parish including 

Arabi and Chalmette.

As the hurricane moved north, flooding in St. Bernard Parish was 

compounded by storm surge overtopping the Forty Arpent Canal levee and 

filling the balance of the parish. Storm surge from Lake Pontchartrain added 

to floodwaters already filling New Orleans East. Storm surge also overtopped 

an embankment at the foot of the Orleans Canal and flooded the City Park 

neighborhood.

By 8:30am the breach at the London Avenue Canal (Figure 5.6)

created a rush of water and sand into the already-flooded Gentilly area. Soon 

afterward, a floodwall failed at the 17th Street Canal, releasing a massive 

wave of water into Lakeview (Figure 5.7). 

Figure 5.4 Industrial Canal, East Bank, North Breach

Floodwater from the Industrial Canal (top) rushed through a breach in the east bank I-wall 

into the Lower Ninth Ward (bottom). Water from the Industrial Canal also flowed into the

Upper Ninth Ward, Bywater, and Tremé neighborhoods from breaches on the west side 

of the canal. (This photo was taken after floodwaters began to recede and water flowed 

from the Lower Ninth Ward back into the Industrial Canal.)
THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why 29

Figure 5.5 Industrial Canal, East Bank, South Breach

Water cascading over the floodwall at this location scoured out the wall’s support and 

caused the breach. Waters from the Industrial Canal (bottom) rushed into the Lower 

Ninth Ward (top) with great force. (This photo was taken after the floodwaters began to 

recede and water flowed from the Lower Ninth Ward back into the Industrial Canal.)

Figure 5.6 London Avenue Canal South Breach

An I-wall failure on the east side of the London Avenue Canal allowed water to spill into 

the Gentilly neighborhood of New Orleans.
30 THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why

Figure 5.7 17th Street Canal Breach

The 17th Street Canal breach began at approximately 6:30am. By 9:00am, torrents of 

water from Lake Pontchartrain were rushing in to flood the Lakeview neighborhood (top 

of photo) and, ultimately, much of midtown New Orleans and surrounding areas.

Figure 5.8 London Avenue Canal North Breach

The I-wall along the west side of the London Avenue Canal failed at about 8:00am, 

allowing water to flood into the City Park neighborhood of New Orleans.
THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why 31

Water from the 17th Street Canal’s 450-foot long breach eventually 

filled New Orleans as far south as Mid-City and west to Old Metairie. Citywide flooding was further compounded by another I-wall failure on the west 

side of the London Avenue Canal (Figure 5.8).

A City Under Water

By the time the most significant I-wall failures had occurred, the peak 

of the surge levels was over. Though surge levels in the Gulf and in Lake 

Pontchartrain dropped, water continued to pour through the many damaged 

levees and floodwalls. This flooding continued until water in the city’s bowlshaped landscape equalized with the water level in Lake Pontchartrain.

By September 1, over 80 percent of the New Orleans metropolitan area 

was flooded as shown in Figures 5.9 and 5.10, with approximately two-thirds 

of the flooding attributed to water flowing through breaches. The remainder 

was attributed to overtopping and significant rain from the hurricane.

Figure 5.9 New Orleans Flooded

Overtopping and breaching at approximately 50 locations in the hurricane protection 

system led to destructive flooding that covered more than 80 percent of New Orleans.
32 THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why

Figure 5.10 Maximum Flooding Depth

By September 1, 2005, portions of Lakeview, Gentilly, New Orleans East, and the Lower 

Ninth Ward were submerged in more than 10 feet of water (orange and red colored 

areas). Significant portions of the city stood in water more than 6 feet deep (green and 

aqua colored areas). 

Pump Stations Shut Down 

During and after Hurricane Katrina, area pump stations could offer no 

relief to the flooding city because they were, themselves, left inaccessible 

and inoperable by the hurricane protection system failures. Figure 5.11 

shows one of the area’s largest pump stations, Station No. 6, submerged in 

floodwaters. 

Figure 5.11 Submerged Pump Station No. 6 

Rapid and far-reaching flooding caused by the hurricane protection system failure left 

most pump stations, such as Station No. 6 (on the 17th Street Canal), inoperable.
33

C H A P T E R 6

Consequences

The people who found themselves in New Orleans on the morning of August 

29, 2005, not only witnessed history, they became a part of it. After many 

grueling days, survivors joined those who had evacuated before the storm 

in the largest mass migration in the United States since the Civil War. In the 

following weeks, receding floodwaters revealed billions of dollars in personal, 

public, and commercial property losses. With this massive property damage 

came the loss of 124,000 jobs.

More than a year and a half later, areas of New Orleans remain, in 

a practical sense, nearly unlivable. While many historic sites of the French 

Quarter and Garden District were, for the most part, spared, elements of 

every day life have been reduced to the bare minimum. Many homes are 

uninhabitable. Others, overrun with mold, require major repairs. Small 

businesses and restaurants remain shuttered, their proprietors unable to afford 

repairs or find housing for workers due to the dramatic loss of residential 

property. Medical care systems are compromised.

These losses, and the loss of people who will never return to New 

Orleans, bring further gaps in the city’s economy as well as to its unique 

social and cultural foundation. As of August 2, 2006, 1,118 people were 

confirmed dead and 135 people are still missing and presumed dead, marking 

the grimmest consequence of the hurricane protection system failure.

Tragic Deaths

Floodwaters rose fast in some neighborhoods on August 29. While many 

people were able to evacuate either before or after the storm, many of the less 

fortunate drowned in the onslaught of water. Rapid flooding caused people to 

lose hold of family members as floodwaters rose. Some victims drowned in 

attempts to save others. In Orleans Parish, many people fled up into their 

attics to escape the rising waters, and then had to hack their way through the 

roofs to find a dry place to stand and wait for rescue. Some people evacuated 

their homes, only to die as they waited for food, water, or medical care. 

Dead bodies eventually floated to higher ground, where passersby mercifully 

covered them with stray tarps or soaked blankets. 

Further from the breached levees and damaged floodwalls, water rose 

approximately 1 foot every 10 minutes. Some elderly or disabled residents 

could not reach their attics fast enough, leaving other family members to 

witness their deaths by drowning. One woman reportedly died of a heart 

attack while trying to escape through the roof. Others, trapped in their homes 

and attics, were found days, weeks, even months later. In St. Bernard Parish, 

many deaths were attributed to drowning in the storm surge.
34 THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why

Though the sick and the elderly were hardest hit (Figure 6.1), causes 

of death were varied. Six deaths resulted from bacterial infection when new 

or existing wounds were immersed in floodwaters. Five people reportedly 

died of carbon monoxide poisoning from improperly using gasoline-powered 

generators during power outages. A bus accident during post-storm evacuation 

attempts killed one person, and one woman died when a helicopter cable 

failed during a rooftop rescue.

Figure 6.1 The Sick and the Elderly Were Hardest Hit

Above, many died when fast-rising floodwaters caught them off guard. Here, evacuees 

pass a drowning victim. Below, the sick and elderly were the most likely to be killed by 

the flooding and its aftermath. More than 30 people drowned when water levels nearly 

reached the ceiling at St. Rita’s Nursing Home (left). Some residents already weak from 

illness died at evacuation centers (right).

Three people committed suicide. Only one person was murdered in the 

immediate aftermath, a remarkable number given New Orleans’s extremely 

high homicide rate (10 times the national rate) prior to Hurricane Katrina. 
THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why 35

However, the risk for additional homicides grew as rescue efforts stalled and 

residents took up arms against potential looting. Hospital pharmacies were 

threatened by armed assailants seeking drugs. The police, responding to 

shootings city-wide, fired on people, killing four.

Of the known fatalities, approximately 52 percent were African 

American, 40 percent were Caucasian, and 8 percent were of other or 

unknown race. Deaths were divided equally between men and women. As 

mentioned earlier, older residents were the hardest hit demographic group. 

Among all races, victims over the age of 70 accounted for 60 percent of all 

deaths.

Exposure, Injury, and Disease

The flood and its immediate aftermath were rife with potential for injury 

and illness. Throughout New Orleans, residents seeking safe haven waded 

through an opaque slush of mud, water, trash, and a mélange of chemicals—

cleaners, solvents, and gasoline leached from flooded homes, businesses, 

and automobiles (Figure 6.2). Added to the mix was output from seven major 

oil spills resulting from the flooding, plus runoff from up to 54 United States 

Environmental Protection Agency (USEPA) Superfund sites in the area. 

Figure 6.2 Exposure to Toxic Chemicals

Survivors waded through a gruesome soup of mud and water plus chemicals and gasoline 

from flooded homes, businesses, and vehicles. Petroleum products left their telltale 

rainbow sheen on floodwaters.

Levels of E. coli and fecal Coliform bacteria in floodwaters were 

similar to typical stormwater runoff levels for the region, but much higher than 

standards for human contact. This exposure resulted in increased incidences 

of gastrointestinal illness, skin infections, and upper-respiratory infections.
36 THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why

Residents hurt themselves while hacking through their roofs or breaking 

windows to escape their flooded houses. People, such as those shown in 

Figure 6.3, sometimes waited on rooftops for days for rescue. Among them, 

several developed rashes from contact with hot roofing materials. Among 

rescue workers, a number of infections and non-infectious rashes were 

identified from contact with contaminated water, mite bites, and excessive 

chafing.

Figure 6.3 Rooftop Rescue

When floodwaters rose high and fast, residents had nowhere to go but up. Once water 

levels topped windows and doors, residents hacked through their roofs to await rescue.

Outbreaks of illness, exacerbated by person-to-person contact in 

close quarters, were reported in a Houston shelter where more than half 

the evacuees suffered acute diarrhea and vomiting for a week, and in Dallas, 

where an antibiotic-resistant strain of staph infection broke out. Fortunately, 

the Center for Disease Control and Prevention (CDC) reported no confirmed 

cases of dysentery, typhoid fever, or cholera.

Due to flooded hospitals and crowding at evacuation centers, the 

health of evacuees suffering from pre-existing conditions (such as diabetes 

and kidney failure) and those requiring prescriptions (for cancer, seizure 

illnesses, asthma, and psychiatric disorders) became compromised. Shortages 

of medication plagued shelters in the following weeks.
THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why 37

Catastrophic Financial Losses

To assess the financial losses in the New Orleans metropolitan area, researchers 

used the most recent inventories and field surveys of land use, properties lost, 

and estimated values. Assumptions made to determine expected personal 

property losses were based on reported flood depths in each neighborhood. 

Residential property throughout the New Orleans metropolitan area (Figures 

6.4 and 6.5) was more than twice as likely as commercial property to be 

destroyed by the failure of the hurricane protection system. 

Figure 6.4 Lower Ninth Ward after Floodwaters Were Removed

The force of the torrential waters raging through Industrial Canal East Bank North 

Breach (upper right) knocked some houses in the Lower Ninth Ward many feet off their 

foundations and completely obliterated others. (This photo was taken after floodwaters 

had been removed.)

Figure 6.5 Residential Property Decimated

The IPET estimates that single-family residential property sustained over $13.3 billion in 

direct losses. (These photos were taken after floodwaters had been removed.)
38 THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why

Direct damages to residential and non-residential capital (commercial, 

industrial, and public buildings) reached approximately $21 billion. Region-wide, 

25 percent of the value of residential properties, including autos, was destroyed 

compared with 12 percent of the value of non-residential properties.

Losses to public structures and damages to infrastructure (roads, 

public transit systems, drainage and sewage systems, potable water service, 

telecommunications systems, and electrical utilities) reached between 

$6 billion and $6.7 billion. Damage to drinking water service resulted in an 

estimated leakage rate of 85 million gallons per day of treated water. The loss 

of electricity, which lasted for weeks, led to massive food spoilage and the 

ruin of more than 300,000 refrigerators, all of which required special handling 

prior to disposal. As floodwaters receded, widespread cleanup efforts began.

Figure 6.6 illustrates just a portion of the extensive public clean-up effort 

required to eliminate health hazards so residents could return to begin their 

own clean-up and rebuilding efforts.

Figure 6.6 Massive Cleanup Efforts

 In Chalmette (top), workers vacuumed a thick layer of oil from city streets. More than 

300,000 refrigerators (below), ruined by spoiled food after weeks of power outages, had 

to undergo hazardous materials removal before disposal. 
THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why 39

Had the Hurricane Protection System Not Failed

For a storm the size of Hurricane Katrina, loss of life and property due to 

heavy rain, wind damage, and overtopping of levees is expected. A modeling 

exercise conducted by the USACE compared expected deaths from the 

hurricane protection system failure with scenarios in which the system did 

not fail. Results of this modeling indicate that had the levees and floodwalls 

not failed and had the pump stations operated, nearly two-thirds of the deaths 

would not have occurred.

Even without levee breaching, Hurricane Katrina’s rainfall and levee 

overtopping would have caused the worst property loss ever experienced 

by New Orleanians. However, as pictured in Figure 6.7, less than half the 

actual property losses—an estimated $10 billion loss in residential and nonresidential capital—would have occurred had the levees not failed and had 

the pump stations operated. This estimate did not consider damages to 

infrastructure and public utilities, which would have suffered far less damage 

had flooding not been as widespread. 

Figure 6.7 Property Damage Modeling Results

Comparing regional property damage from the hurricane protection system failure (left) 

to a scenario in which the levees and pumping stations had not failed (right) indicates far 

less property loss would have occurred. Similarly, nearly two-thirds of deaths could have 

been avoided.

Cascading Financial Impacts

Researchers have compared data quantifying the pre-Katrina economic base 

for the New Orleans metropolitan area with anecdotal post-Katrina data. While 

limited, this preliminary assessment proves useful in estimating the indirect 

economic consequences brought on by the levee failures and the subsequent 

dislocation of hundreds of thousands of residents. However, household, 

business, and policy decisions yet to be made may have a profound impact on 

the region’s long-term economic forecast.

As of June 2006, the population of New Orleans was still less than 

half the pre-Katrina population (more than a million people in 2004 versus just 

over half a million in 2006). Many jobs are still not available due to the reduced 
40 THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why

customer base and the destruction of business property, infrastructure, and 

residences. Total employment in the New Orleans metro area plummeted 25 

percent (from 512,000 jobs to 388,000 jobs) between August (pre-Hurricane 

Katrina) and September 2005 (post-Hurricane Katrina). 

The significant damage to infrastructure will likely slow the recovery 

of population and business activities. Repair work and labor force return has 

occurred unevenly, but predictably, across the area. Where flood water was 

shallow, more recovery has proceeded. In areas where flood water was deep, 

little recovery or reinvestment has taken place. Figure 6.8 illustrates the 

contrast in rebuilding efforts between two neighborhoods—Lakeview, which 

was decimated by floodwaters as high as 10 feet, and a portion of Chalmette 

that saw lower flood levels.

Figure 6.8 Recovery is Slow

Rebuilding efforts vary directly with the level of flooding that occurred. In Lakeview (top), 

where floodwaters reached 8 to 10 feet, City officials have posted survey cards on 

abandoned houses to determine if residents plan to return. In areas where flood levels 

were lower, such as portions of Chalmette (bottom), residents have started repair work 

while they live in Federal Emergency Management Agency (FEMA) trailers. 
THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why 41

Impacts to the economy of the State of Louisiana are significant, 

although impacts to the United States economy from the hurricane and 

flooding were short-lived. In the 2001/2002 fiscal year, combined general 

revenues for the five-parish region, including taxes and other income streams, 

totaled $3.4 billion, more than a third of local government general revenues in 

Louisiana. Since Hurricane Katrina this tax revenue has plummeted. 

Prospects for Economic Growth

A regional economic forecasting model compiled for the IPET study presented 

economic forecasts for the New Orleans area, the rest of Louisiana, and the 

United States population following Hurricane Katrina. Economic outlooks 

reflecting pre-Katrina conditions were used as control values, and two scenarios 

were examined—flat population growth and a more brisk population growth.

Both scenarios yielded some economic growth, but not enough growth 

to reach levels anticipated, pre-Katrina, by 2010. According to the model, the 

economic growth of the New Orleans area will impact the overall growth of 

the state, but has little effect on the Gulf Coast region and the remainder 

of the United States The flat population scenario does, however, have the 

expected impact of increasing growth in the nation, reflecting the contribution 

of evacuees who choose not to return to the New Orleans metro area.

Long Term Health and Safety

Almost every hospital in the New Orleans area was crippled in some way 

from the floodwaters. As of March 2006, only 456 staffed hospital beds were 

available, one-fifth the pre-Katrina number. Less than half the adult acutecare facilities remain open. The Medical Center of Louisiana at New Orleans 

sustained so much damage that it has closed. This leaves a significant gap in 

health-care services for Medicaid patients and the uninsured, and removes 

a Level I Trauma Center from the Gulf Coast region. Residents must seek 

emergency care and other treatment at temporary facilities, as pictured in 

Figure 6.9.

Workers who lost their jobs and medical insurance coverage may or 

may not qualify for Medicaid coverage. Many people may go untreated for 

minor or serious medical conditions. Thousands of doctors and other healthcare providers remain dispersed throughout the country. As of April 2006, New 

Orleans’s physicians-per-resident rate had dropped from a pre-Katrina rate of 

9.6 physicians per 3,200 residents to less than one primary care physician per 

3,200 residents and less than one psychiatrist per 21,000 residents. 
42 THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why

Figure 6.9 Outposts for Care

Due to extensive damage to almost every New Orleans hospital, including the Medical 

Center of Louisiana at New Orleans and its trauma center, residents must seek care in 

temporary medical facilities. Above, an emergency care and dental facility operated out 

of the Ernest N. Morial Convention Center for a time, and was then set up in a gutted, 

downtown department store.

With the exception of mold issues, environmental health impacts—for 

instance, from contaminated air, water, or soil—are not expected to be farreaching. Reports of “Katrina cough” thought to be brought about by the 

presence of higher levels of dust and mold have not been substantiated. Still, 

health officials advised protection for construction workers, waste-handlers, 

and residents during clean-up and rebuilding.

Mold, as shown in Figure 6.10, grew in most homes that remained 

flooded over several weeks, introducing a potential environmental health 

problem. While mold has no established exposure limits, it presents a risk of 

opportunistic fungal infection in immuno-compromised persons. The CDC’s 

measurements of airborne endotoxins that result from molds indicate that 

typical mold growth has reached levels associated with respiratory symptoms 

and skin rash.
THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why 43

Figure 6.10 Overrun by Mold

Mold covering interior walls presents a significant challenge for homeowners determined 

to restore their houses.

Most people exposed to traumatic events, such as serious accidents, 

combat, assault, or natural disasters, will experience feelings such as fear, 

anger, uncertainty, and sorrow. A subset of those exposed will experience 

symptoms of post-traumatic stress disorder, the result of structural and 

functional changes in the brain. Mental health impacts have already been 

observed; the suicide rate in New Orleans is nearly triple the pre-Hurricane 

Katrina suicide rate. Up to 6 months after the hurricane, calls to a city suicide 

hotline had doubled from pre-hurricane rates, despite the significantly smaller 

population. Others exposed to trauma may experience depression and 

substance abuse. 

Evacuees and Their Receiving Communities

Counting pre- and post-hurricane evacuations, Hurricane Katrina displaced 

more than one million people. Evacuees left the city in droves by airplane or 

bus, as shown in Figure 6.11, in the days following the extensive flooding. By 

early October 2006, displaced individuals were located in 369 different cities 

in every state of the nation, with thousands clustered in large southern cities 

such as Houston, Atlanta, Memphis, and Baton Rouge.
44 THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why

Figure 6.11 Mass Migration

The evacuation of New Orleanians before and after Hurricane Katrina represents the 

largest mass migration in United States history since the Civil War. Above, immediately 

following the hurricane, the Louis Armstrong New Orleans International Airport became a 

processing center for rescued people leaving the city. Below, thousands of evacuees left 

the area by bus.

Receiving communities quickly found their services over-burdened. 

Before Katrina, nearly one-half of New Orleans’s residents were either on 

Medicaid or uninsured. These evacuees have created an unanticipated strain 

on other communities’ health-care systems. In Baton Rouge, the addition of 

100,000 evacuees to the city’s pre-Katrina population of 225,000 residents has 

led to over-crowding, traffic jams, and long waits for services. In Houston, 33 

of 189 homicides (17 percent) involved Hurricane Katrina evacuees, although 

they increased the population by only about seven percent.
THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why 45

Impacts to New Orleans’s Culture

The failure of the hurricane protection system, massive infrastructure damage, 

and the lack of jobs and residential properties for residents to return to have 

caused a breakdown in New Orleans’s social structure. Many victims have lost 

homes, schools, jobs, shops, places of worship, and networks of family and 

friends. 

Of New Orleans’s 73 neighborhoods, only eight neighborhoods did not 

flood. Thirty-four were completely inundated. Many neighborhoods remain 

uninhabitable because of damage to residential structures.

Most religious congregations, a key source of community connectedness 

in New Orleans, have not resumed services. Many churches flooded and 

sustained significant damages, and, in the most devastated neighborhoods, 

few parishioners have returned. 

Following Hurricane Katrina, school enrollment (primary and secondary) 

was down 52 percent in the five-parish metro area and down 86 percent in 

Orleans Parish. Students attend schools in other parishes or in cities where 

they have relocated. Enrollment is limited at University of New Orleans and 

Dillard, Xavier, Loyola, and Tulane Universities.

Two of New Orleans’s most famous commodities—fine food and live 

music—remain severely affected. The majority of the city’s musicians have 

not returned to the city (Figure 6.12), and many restaurants damaged by the 

flooding remain closed. Losses in these two areas affect economic recovery 

as well as the recovery of New Orleans’s social norms. 

Figure 6.12 Awaiting Music’s Return

A piano is removed from music legend Fats Domino’s destroyed home in the Lower Ninth 

Ward. Many musicians have not returned to New Orleans due to a lack of housing and 

damaged performance venues.
46 THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why

The Natural Environment

Although an estimated 295 square kilometers (114 square miles) of wetland 

loss has been attributed to Hurricane Katrina, the loss was independent of 

failures of the hurricane protection system. The observed loss in wetlands 

—and associated losses in plants and animals—is consistent with long-term 

wetland loss trends plus losses from the storm surge (Figure 6.13).

Figure 6.13 Wetlands Loss

Approximately 114 square miles of wetland loss resulted from storm surge and typical 

wetland loss trends, not from the hurricane protection system failure.
47

C H A P T E R 7

Direct Causes of the Catastrophe

What is unique about the devastation that befell the New Orleans area from 

Hurricane Katrina—compared to other natural disasters—is that much of 

the destruction was the result of engineering and engineering-related policy 

failures. The levees were engineered structures intended to protect people 

from high water—the very disaster that they failed to prevent. The pump 

stations were engineered structures intended to remove rainwater from the 

New Orleans bowl, but they weren’t always designed to withstand a hurricane 

or levee breach and they failed to pump. 

As outlined in Chapter 5, the levees in the New Orleans area breached 

at about 50 distinct locations. At least seven of the major failures were related 

to breaching of levees containing I-walls. The I-wall failures were particularly 

devastating because of the heavy residential development and low elevations 

they were attempting to protect. The rest of the levees breached when they 

were overtopped by the floodwaters, which eroded the levee material away. 

17th Street Canal Breach

At about 6:30am on August 29, a 450-foot-long section of I-wall along the 

east side of the 17th Street Canal failed, sending torrents of water into New 

Orleans’s Lakeview neighborhood. The water level in the 17th Street Canal at 

the time of failure was about 5 feet lower than the top of the wall, well below 

the design water level. 

A cross-section of the levee and flood wall is shown in Figure 7.1. The 

levee and floodwall were built over a layer of organic soil called peat or marsh, 

which, in turn, overlays a layer of very soft clay. A principal concern with levees 

founded on soft soil is the possibility that the entire levee might slide either 

into the canal or away from the canal because of the low strength of the soft 

soil. This is a design problem that engineers deal with routinely. Indeed, the 

mechanism of failure was the levee sliding away from the canal. 

Figure 7.1 Cross-Section of 17th Street Canal Levee and Floodwall

The levee and I-wall failed by sliding away from the canal along a failure surface in the 

weak soft clay below the levee. 
48 THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why

Soil Strength Over-estimated

To prevent the failure of a levee or I-wall such as that along the 17th Street 

Canal, the “resisting forces” (i.e., the strength of the underlying soil) must be 

greater than the “driving forces” imposed upon it (i.e., the weight of the levee 

and the pressure of the canal water acting against the levee and the wall). The 

“factor of safety” against failure occurring is the ratio of the shear resistance 

of the soil divided by the shear force that develops along a potential sliding 

surface. 

If the factor of safety is less than one, failure will occur. Because the 

factor of safety is directly proportional to the soil strength, determining the 

soil strength is one of the most important decisions that an engineer makes 

for levee design.

The engineers responsible for the design of the levee and I-wall overestimated the soil strength—meaning that the soil strength used in the 

design calculations was greater than what actually existed under and near the 

levee during Hurricane Katrina.

Figure 7.2 illustrates how the soil data were mis-interpreted. During 

a soil investigation, samples are obtained from drill holes and tested in a 

laboratory to determine soil properties. From a plot of the soil strength data, 

conservative values should be selected for design. 

For the 17th Street Canal failure, the critical zone for sliding was the 

soft clay between elevations -15 and -30 feet. The soil strength value chosen 

for design is highlighted by the red line. There are twice the number of data 

points to the left of (weaker than) the design shear strength profile than to 

the right (stronger than). The engineers made an unconservative (i.e., erring 

toward unsafe) interpretation of the data: the soil below the levee was actually 

weaker than that used in the I-wall design. 

Two additional important factors led to an over-estimate of the soil 

strength below the 17th Street Canal. First, the data shown in Figure 7.2

represent the values from borings drilled along the centerline of the levee 

over a distance of 8,000 feet—about 11⁄2 miles. Lumping together data over 

distances is not uncommon. However, care must be taken in areas where 

there is geologic variability—such as in the New Orleans area—where 

the soil is stronger in some areas and weaker in others. Data from borings 

closest to the 17th Street Canal failure indicate that the actual average soil 

strength in the critical stability zone at the breach site is around 0.13 tons per 

square foot (tsf), compared to the engineer’s design strength of 0.19 tsf—or 

approximately 32 percent lower. 
THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why 49

Figure 7.2 Plot of Soil Strength beneath the 17th Street Canal Levee 

Mis-interpretation of soil data below the 17th Street Canal levee was one of three primary 

reasons the I-wall failed. 

Second, the data shown in Figure 7.2 were obtained from borings drilled 

along the centerline of the levee; the key word here is the word “centerline.” 

It is well understood that clay soil is consolidated and strengthened by the 

weight of overlying soil. The soft clay below the centerline of the levee was 

therefore stronger than the soil below and beyond the edge of the levee. 

Recent soil investigations by the USACE verify this: the orange-dashed line 

in Figure 7.2 shows the average strength profile below the centerline of the 

levee, whereas the blue-dashed line shows the lower strength beneath and 

beyond the toe of the levee slope. The design engineers did not take this into 

account, and, accordingly, over-estimated the strength of the soil outside the 

footprint of the levee.

Factor of Safety 

Over-estimating the soil strength below the levee set the stage, but was 

not the sole cause of the 17th Street Canal failure. The factor of safety for 

slope stability analyses such as these—the resisting forces divided by driving 

forces—must be greater than one. The higher the factor of safety above one, 

the less likely the levee will fail. 
50 THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why

The target factor of safety chosen by the design engineers for the 

17th Street Canal levee and floodwall design was 1.3. A target factor of 

safety of 1.3 is at the low end of generally accepted engineering values, and 

is inconsistent with current USACE standards. Key USACE design guidance 

documents call for a target factor of safety of at least 1.4 to 1.5 under longterm conditions. 

The cumulative effect of using a target factor of safety of 1.3 and 

over-estimating the soil strength—a compounding error—was disastrous. 

The design was simply too close to the margin of safety, allowing little or no 

room to account for variables or uncertainties.

The Water-Filled Gap

Another critical engineering oversight that led to the failure of the 17th Street 

Canal involves not taking into account the possibility of a water-filled gap, 

which is illustrated in the diagram in Figure 7.3. The water-filled gap turned 

out to be a very important aspect of the failures of the I-walls around New 

Orleans.

Figure 7.3 The Water-Filled Gap

As floodwaters pushed against the I-wall and the I-wall leaned away from the canal, water 

flowed into the gap created between the wall and the soil behind it. The water-filled gap 

was an important factor in several I-wall failures. 

Figure 7.4 illustrates the reason the water-filled gap led to failure 

of several I-walls. The first diagram in Figure 7.4 shows the critical sliding 

surface passing beneath the 17th Street Canal I-wall and through soil between 

the wall and the canal—without a water-filled gap. The shearing resistance 

provided by this segment along the failure surface adds to the stability. In 

the second diagram of Figure 7.4, representing the actual situation with a 

gap, the critical sliding surface starts at the base of the water-filled gap. The 

sliding surface cuts through less soil, so that less resisting soil strength can 

be mobilized. In addition, the pressure on the wall generated by the water in 

the gap adds to the forces tending to slide the wall away from the canal.
THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why 51

Analyses indicate that, with the presence of a water-filled gap, the 

factor of safety is about 30 percent lower. Because a factor of safety of 1.3 

was used for design, a reduction by 30 percent would reduce the factor of 

safety to approximately one: a condition of incipient failure.

Figure 7.4 17th Street Canal Failure Mechanism

1: Sliding surface without a water-filled gap.

2: Sliding surface with a water-filled gap.

Without the water-filled gap (top), the critical sliding surface is longer, which increases the 

stability of the wall. The wall with the water-filled gap (bottom) has a significantly lower 

factor of safety. As the water level rose in the canal, the factor of safety decreased from 

1.21 to 1.0, or incipient failure. 

In 1985, the USACE performed a full-scale field test on an I-wall to 

help verify design criteria for I-walls under high-water conditions. This field 

test, although focused on structural design criteria, also revealed the potential 

for large I-wall deflections. The observed deflections, nearly 3 inches at the 

ground surface, caused researchers to include the following statement in the 

report: “Although the test wall was not loaded to ‘failure,’ ... failure may 

have been imminent.” (USACE (1988), “E-99 Sheet Pile Wall, Field Load Test 

Report,” Lower Mississippi Valley Division, Vicksburg, MS, 85 p.)
52 THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why

In the late 1990s, sophisticated computer modeling of the field test 

indicated that, “As the water level rises, the increased loading may produce 

separation of the soil from the pile on the flooded side (i.e., a tension crack 

develops behind the wall). Intrusion of free water into the tension crack 

produces additional hydrostatic pressures on the wall side of the crack...”

Thus, USACE researchers clearly recognized the potential for a 

water-filled gap to develop. This knowledge has now been found to be very 

important. As research and new information evolved in the 1980s and 1990s, 

the design of the existing I-walls was not checked for safety and stability in 

the light of new information.

London Avenue Canal South Breach 

The London Avenue Canal South Breach occurred around 6 to 7am on 

August 29th, sending tons of sand and water into the New Orleans Gentilly 

neighborhood. As with the 17th Street Canal, the water level in the London 

Avenue Canal at the time of failure was about 5 feet lower than the top of the 

wall, well below the design water level. 

The soil beneath the London Avenue Canal South Breach area is sand 

beneath the marsh layer, rather than soft clay, as was the case at the 17th 

Street Canal breach location. A cross-section describing the failure mechanism 

is shown in Figure 7.5. 

Figure 7.5 Cross-Section of London Avenue Canal Levee and Floodwall

The levee and I-wall failed when pressure from the water seeping through the sand below 

the levee caused the marsh layer to crack. The sand then flowed out with the water, 

undermining the levee and I-wall. 

As the water level rose in the canal, water seeped into the highly 

permeable sand, flowing under the levee toward the land-side of the wall. The 

water pressure acted upward on the bottom of the marsh layer. The stability 

of the levee under this type of condition hinges on whether the weight of 

the overlying material is great enough to resist the uplift water pressure 

acting upward on it. In well-designed structures, the uplift water pressure 

is never allowed to come close to the weight of the overlying soil. At the 
THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why 53

London Avenue Canal South Breach, however, the water pressure exceeded 

the weight of the marsh layer and the topsoil above it. 

The marsh layer was lifted up off the sand and cracked open, which 

allowed water to rush through the cracks. After the cracks developed, the 

upward-rushing water carried sand with it, gouging and scouring a hole that 

rapidly expanded and worked its way back under the levee, undermining and 

destroying it (Figure 7.6). 

Figure 7.6 Cars and Houses Partially Buried by Sand

Tons of sand were washed out from beneath the levee and floodwall at the London 

Avenue Canal South Breach and flowed into the adjacent neighborhood. (This photo was 

taken after floodwaters had been removed.) 

Oversimplified Assumptions 

The mechanisms of seepage and subsurface erosion have been well known 

for decades. Seepage beneath levees is discussed in depth in the USACE 

Engineer Manual EM1110-2-1913, “Design and Construction of Levees.” 

Chapter 5, “Seepage Control,” begins as follows:

“Without control, underseepage in pervious foundations beneath 

levees may result in (a) excessive hydrostatic pressures beneath 

an impervious stratum on the landside, (b) sand boils, and (c) 

piping beneath the levee itself. Underseepage problems are 

most acute where a pervious substratum underlies a levee and 

extends both landward and riverward of the levee and where a 

relatively thin top stratum exists on the landside of a levee.”
54 THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why

The design engineers of the London Avenue Canal levees and 

floodwalls did evaluate seepage. However, it was not apparent from the 

design information reviewed by the Hurricane Katrina External Review 

Panel that the potential uplift of the marsh layer was accounted for properly. 

Flow nets were drawn, but none included the marsh layer. The potential for 

uplift was assessed, but calculations used a critical hydraulic gradient value 

appropriate for soil, not for marsh. 

Because the problem with uplift for situations such as those existing 

at the London Avenue Canal is so well known, the Hurricane Katrina External 

Review Panel would have expected the design memoranda to contain 

a thorough, well-documented assessment of the potential for uplift of the 

marsh. No logical explanation for the lack of such information in the design 

memoranda could be identified.

Recent computer analyses of the London Avenue Canal South Breach 

indicate that the water pressures in the sand were sufficient to lift and rupture 

the marsh, and that the ensuing cracked condition would be expected to rapidly 

lead to erosion and collapse. The implication is that if a more rigorous analysis 

had been performed at the time of design, the potential problem would have 

been predicted and corrective action taken. Proactive measures to control 

the seepage—such as extending the depth of the sheet pile wall or installing 

relief wells—were not employed, leaving no redundancy or secondary means 

to protect from severe underseepage problems. Unfortunately, there was no 

second line of defense.

The Water-Filled Gap—Again

The failure of the London Avenue Canal I-wall was exacerbated by, and perhaps 

even caused by, the water-filled gap that developed behind the wall. Just as 

with the 17th Street Canal, the water in the London Avenue Canal pushed 

the I-wall away from the canal side, leaving a gap between the I-wall and the 

levee, which filled with water. As shown in Figure 7.7, the elevated water 

pressures were brought much closer to the land-side of the levee, significantly 

increasing the uplift forces on the clay and worsening the situation. As with 

the 17th Street Canal, a water-filled gap was not considered in the design of 

the London Avenue Canal levees and floodwalls. 
THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why 55

Figure 7.7 London Avenue Canal South Breach Failure

1: Conditions without a water-filled gap.

2: Conditions with a water-filled gap.

Without the water-filled gap (top), there is less pressure on the underside of the marsh 

layer. The water in the water-filled gap (bottom) exerts significantly higher pressure on the 

marsh layer because it is closer.

London Avenue Canal North Breach

The London Avenue Canal North Breach occurred on the west side of London 

Avenue Canal around 7 or 8am on August 29th, allowing water to flood into 

the adjacent neighborhood. The upper 15 feet or so of soil beneath the London 

Avenue Canal North Breach consists of marsh underlain by a thick stratum 

of sand, similar to the conditions at the London Avenue Canal south failure. 

However, the sand at the North Breach was much looser and weaker than the 

sand at the South Breach. 

The levee and I-wall probably failed in much the same way as the 17th 

Street Canal failure, in which the driving forces (the weight of the levee and 

the pressure of the canal water against the wall) exceeded the resisting forces 

(the strength of the underlying soil). The sliding failure was exacerbated by 

underseepage and associated water pressures. 

Recent analyses of the London Avenue Canal North Breach indicate 

that the failure probably would not have occurred had a water-filled gap not 

developed. Factors of safety against stability failure without a crack were 

computed to be around 2.0. With a crack, the factor of safety was about 1.0 

at the water elevation associated with failure.
56 THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why

Industrial Canal East Bank North Breach

The failure of the Industrial Canal East Bank north I-wall was likely the source of 

the earliest flooding (observed at 5:00am) in the Lower Ninth Ward. The water 

level in the Industrial Canal was below the top of the floodwall. The soil conditions 

in this area consisted of marsh deposits overlying soft clay, which overlies sand.

The Industrial Canal East Bank north I-wall failed in much the same 

way as the 17th Street Canal I-wall failed: by slope failure along a sliding 

surface in the marsh. As with the 17th Street Canal, the presence of a waterfilled gap (not considered during design) greatly reduced the factor of safety. 

Industrial Canal East Bank South Breach and 

Industrial Canal West Bank Breach

Both the Industrial Canal East Bank south I-wall and Industrial Canal West 

Bank I-wall were overtopped by floodwaters from Hurricane Katrina. The peak 

water level was estimated to be 1.7 feet above the tops of the floodwalls and 

levees. The apparent failure mechanism is shown in Figure 7.8 and 7.9.

Figure 7.8 Overtopped I-wall Failure Mechanism 

1: Floodwaters overtop the I-wall.

2: The water scours soil from the land-side of the I-wall and washes it away.

3: I-wall fails due to lack of foundation support.

Water flowing over the floodwalls scoured and eroded the land-side of the levee at the 

base of the walls. The sheetpiles that support the I-walls were undermined. In some 

locations, the sheetpile walls may have lost all of their foundation support, resulting in 

failure of the wall. 
THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why 57

Figure 7.9 Industrial Canal East Bank South Failed I-wall

Cascading floodwaters gouged a deep trench on the land-side of the Industrial Canal. 

Without foundation support from the soil, the sheetpile wall (upper left) was tossed aside. 

(This photo was taken after floodwaters had been removed.) 

Industrial Canal West Bank South and All Other Levee 

Breaches

Earthen levees without I-walls all around New Orleans—including the levee at 

the Industrial Canal West Bank South breach—were overtopped by Hurricane 

Katrina’s storm surge. Out of the 50 total estimated levee breaches systemwide, the majority can be attributed to overtopping and erosion. The failure 

mechanism from overtopping is shown in Figure 7.10.

Levees constructed with properly compacted clay with a good grass 

cover appeared to have withstood the storm the best, as shown in Figure 

7.11. Levees with higher silt and sand content in the embankment material 

—or levees built with hydraulic fill (in which the levee material was mixed 

with water to create a slurry, then pumped or flowed into place)—sustained 

the worst erosion damage, and in some cases were completely washed 

away, as shown in Figure 7.12.
58 THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why

Figure 7.10 Overtopped Levee Erosion Failure Mechanism

1: Floodwaters overtop the levee.

2: The water scours soil from the crest and land-side of the levee and washes it away.

3: Some levees constructed of sand and silt washed away completely.

Water overtopping the levees caused serious scour and erosion. Some levees were 

completely washed away.

Figure 7.11 Levee Under the Paris Road Bridge in New Orleans East

Even though this earthen levee was overtopped (as was shown in Figure 5.1), it sustained 

relatively minor damage. (This photo was taken after floodwaters had receded.) 
THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why 59

Figure 7.12 Obliterated Levee along the Mississippi River-Gulf Outlet

Many levees that were constructed with hydraulic fill severely eroded or washed away 

entirely. (This photo was taken after floodwaters had receded.)

Pumping System: Useless During Hurricane Katrina

The pumping stations throughout the New Orleans area could have been—but 

were not—an integral part of the hurricane protection system. Most hurricanes 

and tropical storms bring heavy rainfall, but the pump stations were designed 

only to remove stormwater runoff and routine seepage water from the interior 

drainage system and pump it into Lake Pontchartrain or other nearby bodies 

of water. 

During Hurricane Katrina, more than 12 inches of rain fell on parts 

of New Orleans. During and after Hurricane Katrina, a few pump stations 

operated, but their output, approximately 18,000 cubic feet per second (about 

16 percent of total pumping capacity for the region), played no significant role 

in lowering floodwaters because the pump stations were not located in the 

areas of worst flooding.

Pumping stations could not be operated for many reasons. Nearly all 

pump station operators in Jefferson and St. Bernard Parishes were evacuated 

when Hurricane Katrina threatened the area because the stations were 

not designed to withstand hurricane forces. Without operators, the pump 

stations lay idle. The storm knocked out electrical power early on, and many 

of the pump station engines cannot run without electricity. Pump stations 

themselves were flooded by water from levee overtopping and floodwall 

breaching, causing widespread equipment damage and failure. The buildings 

housing many of the older pump stations could not withstand the wind and 

water forces from the hurricane and sustained significant damage. 
60 THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why

Even if the pumping system had survived the hurricane, it simply 

would not have been able to pump the huge amount of water that flooded into 

New Orleans because of overtopping and breaches. Ironically, the discharge 

from the stations was hard-piped into the same canals and waterways that 

had experienced significant breaches. Even if the pumps had continued to 

operate, they would have recirculated water back into the canals, only to have 

it flow back through the breaches. 

Unintended reverse flow through some pumps in Jefferson Parish 

even added to the flooding. While methods were available to prevent reverse 

flow, they depended on human operators and electrical power, neither 

of which were present at the time. In the absence of automatic backflow 

preventers within the pump stations, water in the canals flowed through 

some idle pumps back into the city.
61

C H A P T E R 8

Contributing Factors

Chapter 7 outlined the direct physical causes of the New Orleans hurricane 

protection system failures. This chapter describes the contributing factors. 

With the benefit of hindsight, we now see that questionable engineering 

decisions and management choices, and inadequate interfaces within and 

between organizations, all contributed to the problem. 

Hurricane Katrina simply overwhelmed the hurricane protection 

system. The storm’s forces exceeded the hurricane protection system’s ability 

to withstand them. No one person or decision is to blame. The engineering 

failures were complex, and involved numerous decisions by many people 

within many organizations over a long period of time. 

Risk to New Orleans Not Fully Appreciated

In terms of large engineered systems such as nuclear power plants or dams, 

the concept of “risk” captures both (a) the consequences to human health 

and safety if a failure were to occur, and (b) the probability of a failure. A 

hurricane protection system is a large engineered system like a nuclear power 

plant or a dam, and comprises the same complicated infrastructure and 

management issues. Therefore, it is helpful to look at risk through the lens of 

risk quantification for one of those structures.

A common approach for quantifying and comparing risks is to develop 

a risk evaluation chart, as shown in Figure 8.1, which is based on the United 

States Bureau of Reclamation’s (USBR’s) guidelines for public protection for 

major dams. “Thresholds” have been established—based on engineering 

judgment—that represent the level of risk that a society is willing to accept 

in order to benefit from accepting that risk. For combinations of fatalities 

and frequencies that plot above the upper line in Figure 8.1, there is “strong 

justification for taking actions to reduce risk for both long-term and short-term 

continued operations.”

Relative to what people are generally willing to accept or tolerate for 

dams, the level of risk to the residents of New Orleans was very high. For 

instance, if the hurricane protection system had been treated as a major dam, 

it would have needed to be designed so that the likelihood of failure would 

occur roughly once in 100,000 years to once in 1,000,000 years of operation. 

The red box shown in Figure 8.1 is an approximate graphical representation of 

the historical performance of the hurricane protection system: a catastrophic 

failure, resulting in approximately 1,000 fatalities, which occurred once in 40 

years of operation.
62 THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why

Figure 8.1 Risk Evaluation Chart

The USBR guidelines for achieving public protection in dam safety are shown in yellow. 

The risks posed by New Orleans’s hurricane protection system (shown in red) were 

significantly higher than people are generally willing to accept. 

The risk that society is willing to tolerate from a dam is not necessarily 

the same as that from a hurricane- or flood-protection system, primarily because 

the systems are different in terms of, for instance, size, resiliency, the speed 

with which an emergency develops, and the options available during actual 

emergencies. Among other differences, a dam is typically several thousand feet

long, whereas a levee system is several hundred to several thousand miles long. 

Dams are generally more resilient than levees because they have emergency 

spillways to divert excess water, thus protecting the dam structure from 

catastrophic failure. Reservoir water levels are monitored, and water levels tend 

to rise slowly, as opposed to storm surges that rise rapidly. Areas downstream 

of the dams have emergency action plans in place to protect downstream 

residents. Also, evacuation of rural areas where most major dams are located is 

far easier than evacuation of major cities such as New Orleans. 

Unlike a major dam in the United States, the risks associated with 

New Orleans’s hurricane protection system had never been quantified prior to 

Hurricane Katrina. As a result, the residents of New Orleans could not have 

known the actual risks with which they were living. Risk quantification could 

have raised the awareness of planners and policy-makers so they understood 

that this system might have been massively under-designed relative to the 

standards for other critical life-safety infrastructure.

One of the most glaring results of not taking risk into account in 

the design and construction of the hurricane protection system is this: the 

consequence of failure—catastrophic loss of life—did not seem to be 

acknowledged. If nothing else, understanding these risks could have led to 

a much more proactive and effective evacuation program for people to be 

removed from harm’s way.
THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why 63

Critical questions need to be answered about hurricane-induced levee 

and floodwall failure. What is the risk? How much risk is acceptable? How 

can this level of risk be effectively communicated? How should the hurricane 

protection system be designed based on risk? Work to define the frequency 

of hurricanes in New Orleans is on-going. It appears that Hurricane Katrina 

had a probability-based recurrence interval in the range of 50 to 500 years, 

meaning that, in the future, a storm such as Hurricane Katrina has 1 in 50 to 

1 in 500 chance of occurring in any one year. Furthermore, work to define the 

probability that the hurricane protection system would fail from the hurricane 

forces is also on-going. 

Hurricane Protection System Constructed Piecemeal

The southeast Louisiana hurricane protection system was planned, designed, 

and constructed over four decades without a system-wide approach or 

integration with land use, emergency evacuation, or recovery plans. Originally, 

the system grew in response to the need to protect from floods and to remove 

rainfall from the city. At some point, the decision was made to incorporate 

hurricane protection. Construction of the hurricane protection system began 

in earnest following Hurricane Betsy in 1965. Construction was not scheduled 

for completion until 2015. 

The hurricane protection system, however, is a system in name only. 

In reality, it is a disjointed agglomeration of many individual projects that were 

conceived and constructed in a piecemeal fashion. Parts were then joined 

together in “make-do” arrangements. 

For example, the pump stations at the south ends of the 17th Street, 

Orleans (Figure 8.2), and London Avenue Canals are old masonry structures 

that were built nearly a century ago to pump out rainfall. Although they were 

thought of as being part of the hurricane protection system, they were never 

strengthened or retrofitted. As a result, the pump station walls could not 

resist the hydrostatic (water pressure) loads caused by a storm surge. 

In addition to the gaps at the pump stations, there are hundreds of 

penetrations for roadways, rail lines, and pipelines throughout the levee 

system. Many of these penetrations have gates that are supposed to be 

moved into place under flood conditions either automatically or by hand 

operation. It was found, however, that many of the closure systems were 

either missing or inoperable, and offered little resistance to floodwaters.
64 THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why

Figure 8.2 Pump Station No. 7 on the Orleans Canal

The buildings housing the pump stations were not strengthened to withstand high water 

pressures from a storm surge. At Pump Station No. 7, a deliberate gap was left between 

the I-wall (top) and the pump station (bottom) to allow the water to flow around, so as not 

to damage the pump station. 

The gates for the levee penetrations are often supported by concrete 

and steel structures, built several feet higher than the adjacent earthen levees. 

Many levee breaches occurred immediately adjacent to penetration structures 

where the floodwaters preferentially overtopped the lower earthen sections, 

which are much more erodible than the adjacent structures. Segmented 

construction of levees sometimes resulted in abrupt discontinuities in top 

elevations as well. For example, there are several reaches of levee where the 

concrete I-wall ends abruptly. The steel sheet pile wall continues at a lower 

top elevation, eventually transitioning to an earthen levee, again several feet 

lower in elevation. As with the penetration structures described above, water 

flowed over the more fragile, erodible sections first because the tops were 

lower, resulting in failure in numerous locations (Figure 8.3). 
THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why 65

Figure 8.3 Failed I-Wall and Levee Sections

The levees and I-walls were constructed piecemeal with different top elevations and of 

different materials: earth, steel, and concrete. The floodwaters preferentially attacked the 

lower-elevation erodible earth first, causing major breaches.

Hurricane Protection System Under-designed

The USACE defines the standard project hurricane (SPH) as a 

hypothetical hurricane intended to represent the most severe combination of 

hurricane parameters that is reasonably characteristic of a specified region. 

The definition “reasonably characteristic” implies that the SPH is not an 

extreme hurricane event—particularly when compared with the probable 

maximum hurricane (PMH), which the National Weather Service defines as “a 

combination of meteorological parameters that will give the highest sustained 

wind speed that can probably occur at a specified coastal location.” 

The relationships between the meteorological parameters (central 

pressure index, forward speed, wind direction, and wind speed) are 

interrelated and complex. It appears that the USACE: 

• Chose SPH meteorological parameters at the low end of the range 

of 101 to 111 mph listed by the USWB (now the National Weather 

Service) in 1959 as representative maximum wind speeds for a 

hurricane striking New Orleans 
66 THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why

• Did not evaluate the hurricane protection system for the effects of a 

more severe storm such as the PMH, 

• Did not update its SPH meteorological parameters when the 

National Weather Service issued revised numbers in 1979, and

• Did not improve previously designed and constructed components 

of the hurricane protection system to match updated design criteria.

Consistently using the SPH—when more severe hurricane parameters 

had been defined—led to hurricane protection systems that were not strong 

or high enough to withstand the forces of Hurricane Katrina. As an example, 

the Lake Pontchartrain and Vicinity Hurricane Protection Project was designed 

for a surface wind speed of 100 miles per hour (mph), even though the 1959 

stated SPH values were 101 (moderate) and 111 (high) mph. The National 

Weather Service’s 1979 PMH stated values for surface wind speed were 151 

(moderate) and 160 (high) mph. Hurricane Katrina’s maximum wind speed 

was measured at 161 mph as it traversed the Gulf of Mexico. 

While it is clear that using a stronger wind field would have led to a 

higher estimated surge level, without extensive modeling there is no way 

to predict how much higher the levees would have been had the PMH been 

used instead of the SPH. Regardless of the actual numbers, had the hurricane 

protection system been evaluated using PMH criteria, the consequences of 

a more severe storm could have been incorporated. For example, levees 

susceptible to overtopping and erosion could have been armored. Pump 

stations could have been strengthened. More comprehensive evacuation 

programs could have been instated. The USACE’s apparent non-conservative 

selection of the design hurricane is inconsistent with that needed to protect 

public safety when an extreme natural force such as Hurricane Katrina strikes. 

Many Levees Not High Enough

Using the SPH and associated meteorological conditions ultimately resulted in 

the hurricane protection system being under-designed. However there were 

other factors that compounded the problem of the levees being unable to 

withstand the storm surge from Hurricane Katrina. 

Establishing an accurate vertical datum (the basis from which 

all elevations are measured) is a necessary first step for the design and 

construction of all engineered structures. Over time, the New Orleans levees 

and floodwalls were designed relative to local mean sea level. However, 

some were constructed relative to datums that were incorrectly assumed to 

be equal to (or offset from) the local mean sea level data (Figure 8.4). 
THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why 67

Figure 8.4 Discrepancies between Design and Construction Elevations

Because of errors in the reference datums, segments of the hurricane protection system 

were constructed so that the top elevations are lower than intended by the design. 

It is well understood that the entire New Orleans region is subsiding. 

The average rate of subsidence is about 0.2 inches per year, although rates in 

excess of 1 inch per year occur at some locations. Compounding the problems 

of using improper datums was the fact that designers and engineers did not 

build in an allowance for subsidence in designing the hurricane protection 

system. Prudent engineering would dictate that the levees and floodwalls be 

built higher than needed, so that over time, as the ground subsided, the levees 

and floodwalls would still be high enough to protect against floodwaters. This 

was not done. 

A “freeboard” (extra height at the top of the wall to accommodate 

waves) allowance was included, but the freeboard was not intended to 

compensate for subsidence impacts. In many projects, the freeboard has 

been completely lost to subsidence. In older parts of the system, along 

the Industrial Canal (built more than 35 years ago) for instance, the impact 

of subsidence plus incorrect use of datum has resulted in the levees and 

floodwalls being up to 3 feet lower than the original design. The peak storm 

surges were generally only 1 to 3 feet above the tops of the levees and walls; 

therefore, had the tops of levees and floodwalls been at the proper elevations, 

fewer overtoppings and breaching failures would have occurred. 

USACE officials have stated that Congressional authorization would 

not allow the USACE to consider water levels above “authorized levels” as 
68 THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why

estimated from the SPH. By this logic, the USACE did not specify the tops of 

the levees to be above authorized levels to account for possible subsidence. 

Similarly, the USACE did not call for armoring to protect from erosion caused 

by overtopping. 

The result of these ill-considered decisions­ —coupled with the fact that 

the area is experiencing ongoing subsidence—is that the tops of some levees 

and floodwalls are as much as several feet lower than originally intended. 

Floodwaters from Hurricane Katrina more easily overtopped these levees. If 

it were not for the fact that the levees breached and I-walls toppled due to 

geotechnical failures (as described in Chapter 7), the overtopping caused by 

walls that were too low would have been the major source of flooding in New 

Orleans. 

No One Entity Is In Charge of Hurricane Protection

In addition to discontinuities in the physical hurricane protection system 

caused by its piecemeal construction and incorrect elevations, there were 

discontinuities in organizational responsibility for the hurricane protection 

system as well. The management of the hurricane protection system is chaotic 

and dysfunctional. 

As shown in Table 8.1, various federal, state, and local agencies are 

responsible for the construction, operation, and maintenance of segments 

of the hurricane protection system. No single agency or organization is 

empowered to provide the much-needed system-wide oversight or focus 

on the critical life-safety issues. No formal coalition of agencies is directed 

to provide strategic direction, definition of roles and responsibilities, and 

coordination of critical construction, maintenance, and operations. Indeed, 

it appears that no agency or group of agencies ever defined clear, mutually 

agreed-upon expectations of what the hurricane protection system was really 

intended to achieve.

Table 8.1 Agencies and Organizations Responsible for Portions of New Orleans’s 

Hurricane Protection System

AGENCY ROLE AND RESPONSIBILITY

United States

Congress

Authorization and funding.

USACE Headquarters USACE guidance and oversight.

USACE Engineer

Research and

Development Center

Research to support new design approaches.

USACE New Orleans

District

Design and construction oversight as the “Engineer” 

for each of the five independent levee districts in the 

New Orleans metropolitan area.
THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why 69

AGENCY ROLE AND RESPONSIBILITY

East Jefferson Levee

District

Maintenance and operation of the flood protection 

levee system around the east bank portion of Jefferson 

Parish to protect the citizens of East Jefferson from 

Lake Pontchartrain and Mississippi River flooding.

Lake Borgne Basin

Levee District

Maintenance and operation of 13 miles of the Mississippi 

River Levee, 26 miles of back protection levee, 23 

miles of the Lake Pontchartrain and Vicinity Hurricane 

Protection Levee, the Bayou Dupre Control Structure, 

12 flood gates, the Violet Freshwater Siphon, 55 miles 

of drainage canals, and eight major drainage pumping 

stations.

Orleans Levee

District

Maintenance and operation of the hurricane and flood 

protection improvements for the City of New Orleans 

on the southern shores of Lake Pontchartrain and 

along the Mississippi River, including inspection and 

maintenance of 129 miles of levees and floodwalls, 

189 floodgates, 97 flood valves, and two flood control 

structures. 

Pontchartrain Levee

District

Maintenance and operation of the hurricane and 

flood protection improvements for St. Charles Parish, 

including the southern shores of Lake Pontchartrain, 

the Bonnet Carré Spillway, and along the Mississippi 

River, including inspection and maintenance of 

associated miles of levees and floodwalls.

West Jefferson Levee

District

Maintenance and operation of hurricane and flood 

protection improvements for the west bank of 

Jefferson Parish, including the levee system east 

and west of the Harvey Canal, along each side of the 

Harvey Canal, and along the Mississippi River, including 

inspection and maintenance of more than 50 miles of 

levees and floodwalls and associated floodgates.

Drainage Pump

Stations Department

of Jefferson Parish

Administration, direction, coordination, and 

implementation of major drainage and flood control 

programs and direct construction, operation, and 

maintenance of 340 miles of canal waterways, drainage 

ditches, cross drains, culverts, and internal levee 

systems; 1,465 miles of street subsurface drainage 

systems; and operation and maintenance of 52 

drainage pump stations.
70 THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why

Examples of the consequences of the lack of inter-agency coordination 

are plentiful. For instance, the agencies responsible for floodgates at France 

Road in Orleans Parish (the crossing for the New Orleans Public Belt Railroad) 

include the Port of New Orleans, the Orleans Levee District, the New 

Orleans Public Belt Railroad, and the New Orleans District of the USACE. The 

floodgates were out of service and left open during Hurricane Katrina because 

of repairs, allowing water to flood through them unimpeded. 

Separate organizations control design and maintenance. By necessity, 

the USACE made assumptions that the levees would be maintained properly 

over time. In fact, the levees were not always maintained properly. For 

instance, trees were allowed to grow on the levees, and swimming pools and 

hot tubs had encroached on levee rights-of-way. Although there was likely 

some informal or semi-formal communication between agencies, the group 

of agencies did not work together to ensure that the New Orleans area was 

protected from hurricane damage.

It is only natural that during an emergency situation such as Hurricane 

Katrina, without pre-planning and coordination, major gaps in emergency 

response will occur. Nowhere is this more evident than in Jefferson Parish, 

where the parish president—apparently out of concern for the safety and 

welfare of the pump station operators—ordered the operators to evacuate 

prior to the storm. There was evidently no plan or infrastructure in place 

to enable safe, continuous operation of pumping stations during a major 

hurricane. If the five pump stations on the east bank of Jefferson Parish 

had remained operable, significantly less flooding would have occurred in 

Jefferson Parish, east bank. 

The USACE acts as “Engineer” on behalf of the levee districts. 

However, the USACE’s position is that it cannot do anything that a local 

sponsor (in this case, a levee district) does not approve. Several key USACE 

attempts to implement system-wide solutions were often met by fierce local 

AGENCY ROLE AND RESPONSIBILITY

Sewerage and

Water Board of New

Orleans

Administration, direction, coordination, and 

implementation of major drainage and flood control 

programs and direct operation, construction, and 

maintenance of 90 miles of open canal waterways, 

drainage ditches, cross drains, and culverts; 90 miles 

of street subsurface drainage systems larger than 

36 inches in diameter; and operation and maintenance 

of 22 drainage pump stations.

The Sewerage and Water Board also operates 

and maintains all drainage pump stations in Orleans 

Parish, east and west banks, and is responsible for 

waterways’ trash pick-up and grass cutting.
THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why 71

opposition, and were not approved. For instance, following Hurricane Betsy, the 

USACE proposed providing hurricane protection along the Lake Pontchartrain 

lakefront instead of along the canals. This proposal was strongly opposed by 

the Sewerage and Water Board of New Orleans and by the Orleans Levee 

District, and ultimately dropped by the USACE.

The problems that led to poor decision-making—the root cause of the 

catastrophe in New Orleans—thus lie within and amongst the cultures of 

key organizations. Protecting against life-threatening risk was put on the back 

burner of public priority. Perhaps no one truly realized how catastrophic levee 

failures would be. Perhaps no one was willing to pay the price necessary 

to build a reasonably safe levee system. Perhaps the levee boards became 

distracted by development projects, airports, parks, casinos, or other matters 

that were given priority above the primary task of caring for the levees. 

Perhaps the political will needed to implement a rationally based hurricane 

protection system was simply too great to be achieved. However, to achieve 

a different outcome in the future, these cultures must change, focusing more 

on protecting peoples’ lives and less on “business as usual.”

External Peer Review Lacking

During the design of major engineering projects, senior experts in the 

appropriate fields of engineering are often called in to conduct external peer 

review. These peer reviewers typically provide input on the overall direction of 

the project, the validity of assumptions, the correctness of analytical methods, 

and the design approach. Design peer reviews are conducted to provide a 

completely independent assessment of a public works project.

External peer reviews were conducted on very few, if any, of New 

Orleans’s hurricane protection system projects. In fact, the USACE’s internal 

directives fall short of ASCE’s recommended policies to protect the public health, 

safety, and welfare against the catastrophic failure of water resources projects. 

The USACE’s peer reviews are discretionary, are not triggered by 

sound engineering principles, do not have a mechanism to gauge their fidelity, 

and contain vague processes for selecting reviewers. As a result, questionable 

engineering decisions were made for the New Orleans hurricane protection 

system. Margins of safety were too low in designing the levees. Improper 

datums were used in construction. The standard project hurricane was not 

updated.

The engineering decision-making process became “self-referential,” 

meaning that designers were forced to look to their own organizations to help guide 

decisions, not to the greater engineering community. Individuals within a selfreferential organization can lose step with technological advances and alternative 

solutions. The organizational culture (for instance, “it’s how we’ve always done 

it”) influenced behavior over the many years that the hurricane protection system 

was under design and construction. Proper and effective external peer review 

could have prevented these errors of judgment from occurring.
72 THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why

Funding Process Flawed

As a federal agency, the USACE and its projects are funded by the federal 

government, with a share of the costs borne by the local sponsor. Every year, 

the USACE requests funding. Through the federal budget-setting process, the 

Executive Branch (via the Office of Management and Budget) and the United 

States Congress authorize a project and allocate funding, but not necessarily 

at the same dollar amounts as requested or required. 

Because of the Congressional budgeting process, the stream of 

funding for the New Orleans hurricane protection system was irregular, at 

best. If a project was not sufficiently funded, the USACE was often required 

to delay implementation or to scale back the project. 

This “push-pull” mechanism for the funding of critical life-safety 

structures such as the New Orleans hurricane protection system is essentially 

flawed. The process creates a “disconnect” between those responsible 

for design and construction decisions and those responsible for managing 

the purse-strings. The pressure for tradeoffs and low-cost solutions likely 

compromised quality, safety, and reliability.

The project-by-project approach—in which projects are built over 

time based on the availability of funding—resulted in the hurricane protection 

system being constructed piecemeal, with an overall lack of attention to 

“system” issues. In effect, it appears that the project-by-project approach 

was associated with Congressional limitations. The USACE was forced into 

a “reductionist’s” way of thinking: reduce the problem into one that can be 

solved within the given authority and budget. Focusing only on the primary 

problem to be solved inevitably makes the issues of risk, redundancy, and 

resilience a lower priority. 

Decisions were made, for example, not to armor the land-side of the 

floodwalls and levees in the high-risk areas; this armoring, if installed, could 

conceivably have limited the flood damage from an infrequent storm event 

such as Hurricane Katrina. It has been stated by some that the USACE may 

have considered this option to be outside of their Congressional authority, 

because to armor the levees would apparently concede that the USACE was 

designing for storm surges above the “authorized level.” 

The design and construction of critical life-safety systems is beyond 

the expertise of the Executive Branch or United States Congress. However, 

the Congress exercised tight control over spending and even over design 

criteria. The USACE accepted these controls without fully addressing the 

associated issues, risks, and tradeoffs. For whatever reason, the USACE and 

its local sponsors did not argue vigorously enough for adequate funding to 

provide a high level of assurance for the public safety of New Orleanians. 

 
73

C H A P T E R 9

What Must We Do Next?

Serious deficiencies in the southeast Louisiana hurricane protection 

system must be corrected if the New Orleans area is to avoid a similar 

catastrophe when the next major hurricane strikes. There are flaws in the way 

the hurricane protection system was conceived, budgeted, funded, designed, 

constructed, operated, and managed. 

There is no quick fix for problems of this complexity. Overcoming the 

deficiencies in the New Orleans hurricane protection system—and instituting 

real change in its engineering, management, and governance—will require 

leadership, courage, conviction, and funding.

The lessons learned from Hurricane Katrina also have profound 

implications for other American communities and a sobering message for people 

nationwide: we must place the protection of public safety, health, and 

welfare at the forefront of our nation’s priorities. To do anything less could 

lead to a far greater tragedy than the one we have witnessed in New Orleans.

What follows are ten critical actions the ASCE Hurricane Katrina 

External Review Panel believes necessary. Each action falls under one of four 

required shifts in thought and approach: understand risk and embrace safety; 

re-evaluate and fix the hurricane protection system; revamp the management 

of the hurricane protection system; and demand engineering quality. We 

consider each action essential, and we strongly recommend that each be 

implemented. 

Understand Risk and Embrace Safety

When Hurricane Katrina came ashore, the hurricane protection system failed, 

with tragic consequences. The catastrophe that befell New Orleans was born, 

in part, out of failure to recognize the fragility of the levee system in the face 

of storms of Hurricane Katrina’s magnitude. Few appreciated how devastating 

the consequences of failure could be. There was far too little priority or urgency 

given to the hurricane protection system by political leaders at all levels of 

government, by designers and operators, and by the people who lived in its 

shadow—evidenced by the fact that the system took decades to build and 

remains incomplete yet today. 

The people of New Orleans—and all those who live in hurricaneand flood-prone communities around the country—must understand and 

acknowledge the risks under which they live. From this knowledge comes 

insight into what risks are acceptable for their communities and for the nation. 
74 THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why

CALL-TO-ACTION NUMBER 1:

Keep safety at the forefront of 

public priorities. 

No single authority has ever been charged with responsibility for defining in 

clear, specific, and unambiguous terms what was to be expected from the 

hurricane protection system in the New Orleans region in terms of protection 

from flooding and loss of life. As the hurricane protection system for New 

Orleans was being designed and debated amongst the USACE and state 

and local stakeholders, compromises were made based on cost, land use, 

environmental issues, and other conflicting priorities. Protection of the public’s 

safety was not always the outcome of these compromises. 

It is human nature—both at a personal and institutional level—to lose 

focus of long-term needs in the light of short-term demands. The infrequency 

of major hurricanes tends to lull society into neglect and inaction, but longterm safety must take precedence. Without a significant elevation of safety 

as a priority, the hurricane and flood protection systems in New Orleans, and 

across the nation, have the potential to return to a low priority. All responsible 

agencies in New Orleans and throughout the nation should re-evaluate 

their policies and practices to ensure that protection of public safety, 

health, and welfare is the top priority for the infrequent but potentially 

devastating impacts from hurricanes and flooding.

Consistent inspection, maintenance, and repair of the hurricane 

protection system are essential. We cannot afford to permit our hurricane 

and flood protection systems to deteriorate. The United States Congress 

should establish and fund a program for nationwide levee safety and 

rehabilitation, much as we do for major dams. The levee safety program 

will help ensure that levee structures and components—in New Orleans and 

throughout the country—receive the level of attention needed for critical lifesafety systems. 

CALL-TO-ACTION NUMBER 2:

Quantify the risks.

Assessment of risk is a key engineering function. Engineers must assess and 

communicate clearly to decision-makers and the public how risk-cost-benefit 

tradeoffs will impact performance and safety. They must take an active role in 

formulating public policy and in decision-making at all levels of government.
THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why 75

The IPET has undertaken the critically important effort of quantifying 

the risks associated with the New Orleans hurricane protection system. Using 

sophisticated risk models, the IPET is analyzing the potential consequences 

from a range of storm scenarios. Among the variables considered are hurricane 

intensity, hurricane location and direction of approach, height and strength of 

levees, ability of pump stations to remove water, whether levee penetrations 

are closed, and land elevation and its propensity for flooding. 

The ASCE Hurricane Katrina External Review Panel encourages the 

IPET’s work toward quantifying risk for each geographic region of the New 

Orleans area. Completing this work must remain a very high priority. Only 

then can fully informed decisions be made regarding the future of the region.

The level of risk also changes with time, depending on changes in the 

natural and man-made environment. Therefore, the risk analyses need to be 

updated as new information becomes available.

The USACE should complete the work necessary to quantify 

and effectively communicate the risk as soon as possible, and, because 

risk assessment and communication is not static, should periodically 

update the assessment of risk. This risk assessment approach should be 

extended to all areas of the nation that are vulnerable to major losses 

from hurricanes and flooding.

CALL-TO-ACTION NUMBER 3:

Communicate the risks to the public and 

decide how much risk is acceptable. 

The future of New Orleans and the State of Louisiana depends on peoples’ 

confidence in the hurricane protection system. Local, state, and federal 

leaders—in concert with the engineering community—need to embrace a 

common risk-based decision support tool for planning and decision-making. 

These leaders need to initiate and maintain an honest and open dialogue with 

all major stakeholders about the risks of living in a hurricane-prone region. 

The people of New Orleans—and those who live in flood- and 

hurricane-prone communities around the country—must have a voice in 

decisions about the conditions under which they live. Decisions that have 

the potential for profound impact are best based on knowledge, insight, and 

timely, structured debate. 

Local, state, and federal agencies should create and maintain 

quality programs of public risk communication in New Orleans and other 

areas threatened by hurricanes and flooding. The public risk communication 

program should be based on state-of-the-art best practices for process and 
76 THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why

content, and address a full range of pertinent topics. The public needs to know, 

for instance, the probability that a major hurricane will hit a particular region 

and the level of protection provided by their region’s hurricane protection 

system. People also need to know the full range of citizen-based emergency 

preparedness and response options and evacuation plans. 

The ultimate goal of the risk communication program should be to 

produce an informed and engaged public. A number of examples could be 

used as a model for the New Orleans risk communication initiative, including 

the work of the State of California’s Office of Emergency Services as part of 

the Parkfield Earthquake Prediction Experiment in the 1980s, and the work 

done by the United States Geological Survey in the San Francisco Bay area 

after the Loma Prieta earthquake in 1989.

Major hurricanes of the scale of Katrina are infrequent. Without an 

effective risk communication program, people will gradually forget about 

the risks. In doing so, they will unknowingly contribute to the severity of the 

consequences from the next hurricane that strikes.

Re-evaluate and Fix the Hurricane Protection System

The first line of defense in the hurricane protection system for New Orleans 

includes levees and floodwalls to hold back the high water from a storm 

surge, yet it failed catastrophically at more than 50 different locations during 

Hurricane Katrina. There was no second line of defense except for the pump 

stations, which were ineffective. 

Not only did the hurricane protection system have many weak links—

in the form of penetrations, low points, and gaps—but it lacked “redundancy.” 

If one component failed, there was no back-up component or strategy to take 

its place to reduce the damage. Internal levees were not used as much as 

they could have been to isolate various sub-sections of the city and prevent 

floodwaters from spreading. The pump stations, which might have removed 

water from the city more quickly, were not designed to function in a major 

hurricane or mitigate flooding if the levees were overtopped or breached. The 

“system” was not a system.

CALL-TO-ACTION NUMBER 4:

Rethink the whole system, including 

land use in New Orleans. 

The nation learns lessons after every major disaster: lessons in decision-making, 

structural integrity, disaster response, and communications. The nation is now 
THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why 77

at a unique juncture where past mistakes in the hurricane protection system 

for New Orleans can be learned from and rectified. 

The IPET has made excellent progress on the task of identifying 

deficiencies in the hurricane protection system. There is still much to be 

done to build on IPET’s work, and we strongly urge that this work be funded 

and pursued to its completion. Information from the IPET analyses, coupled 

with a clear definition of the public’s expectations (as framed in Call-to-Action 

Number 3), will form the basis for rethinking the entire hurricane protection 

system. 

At the outset, the design hurricane and storm surge levels need to be 

re-assessed and updated using a risk-based approach. The design hurricane 

conditions cannot be static design criteria. Risk and levels of acceptable 

risk evolve with time—as does the knowledge on which storm criteria are 

based.

The future system will incorporate existing infrastructure (such 

as levees and pump stations) but must include other appropriate tools 

and strategies as well. Prudent land-use decisions (for example, limiting 

development in the most flood-prone areas, or establishing minimum firstfloor elevations) can put fewer people and less property at risk. More rigorous 

building requirements can reduce the impact of flooding on structures. A 

more effective hurricane warning, response, and evacuation protocol can 

be instituted and practiced in regular training exercises. Pre-planning can 

expedite recovery and reconstruction after a major hurricane.

The ASCE Hurricane Katrina External Review Panel calls on New 

Orleans and all hurricane- and flood-prone communities around the nation 

to use the lessons learned from Hurricane Katrina to develop roadmaps for 

safety and protection. Local, state, and federal leaders should review the 

overall strategy and systems approach, integrating hurricane protection 

tactics, land-use considerations, and emergency response strategies into 

a coherent and well-thought-out system.

CALL-TO-ACTION NUMBER 5:

Correct the deficiencies.

Hurricane Katrina obliterated many critical hurricane protection structures and 

wreaked great damage on others. The disaster also brought to light many 

weaknesses and deficiencies in the existing system that, if not fixed, will 

remain vulnerable to future hurricanes. The work to be done includes making 

up for past design deficiencies as well as strengthening existing components 

of the system to make them more resilient to damage.
78 THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why

Hurricane Katrina offers a cautionary tale and subsequent mandate to 

other hurricane-prone communities as well. Now is the time to fix deficient 

or damaged parts of existing flood and hurricane protection systems 

throughout the country to provide the intended levels of protection. Local, 

state, and federal leaders should continue the work necessary to correct 

the deficiencies in the hurricane protection systems, and bring this work 

to completion with urgency. In the New Orleans region, “must-do” items 

include:

• Establish mechanisms to incorporate changing information.

The dynamics of the hurricane protection system—such as levee 

heights and meteorological and oceanographic conditions—need 

to be monitored routinely, especially when processes like 

subsidence are known to occur. Advances in surveying technology 

need to be fully utilized to establish and regularly update geodetic 

vertical datum and water surface elevations. Levee design, 

construction, and maintenance must be tied to elevations that 

provide the true level of flood and hurricane protection intended for 

New Orleans. 

• Make the levees functional even if overtopped. During 

Hurricane Katrina, water rushing over the levees severely damaged 

and compromised their integrity. Overtopping of levees due to 

hurricanes is inevitable. To prevent damage, the levees need to 

be armored by resurfacing them with protective non-erodible 

materials.

• Strengthen or upgrade the floodwalls and levees. Floodwalls 

and levees must be fully investigated and analyzed to ensure that 

they have adequate margins of safety against failure, consistent 

with critical life-safety structures. Such was not the case preKatrina, and may not always be the case now.

• Upgrade the pumping stations. Not only was the pumping 

system not fully integrated into the hurricane protection system, 

but many of the pump stations were not strong enough to 

withstand the forces of a hurricane. The pump stations need to 

be made survivable from flooding caused by hurricanes and unanticipated levee breaches. If this is not done, New Orleans will 

remain unnecessarily vulnerable.
THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why 79

Revamp the Management of the Hurricane Protection System

The management of New Orleans’s hurricane protection system 

was dysfunctional because there were too many organizations involved 

in managing individual pieces of the system. No one entity or person was 

in charge. Many agencies had partially overlapping roles, yet there was no 

effective coordination between agencies. 

The members of the ASCE Hurricane Katrina External Review Panel 

believe that correcting the management deficiencies of the hurricane 

protection system is just as important as correcting the physical deficiencies. 

With effective management comes a more unified approach to hurricane 

protection—which is greatly needed in New Orleans. 

CALL-TO-ACTION NUMBER 6:

Put someone in charge. 

No complex program or system can be successful without good leadership, 

management, and someone in charge. The New Orleans hurricane protection 

system evolved over decades under the initiative and management of 

numerous agencies, none of which had definitive authority to adjudicate 

conflicting priorities. Until someone is put in charge of overall management 

and made accountable, organizational dysfunction will continue. 

Local, state, and federal leaders should agree to assign to a single 

individual the responsibility for managing critical hurricane and flood 

protection systems such as the one in the New Orleans area. The ASCE 

Hurricane Katrina External Review Panel recommends that the “person-incharge” or “authority” or commissioner be a high-level, licensed engineer (or, 

alternatively, a panel comprising licensed engineers). We suggest that this 

authority should have the wherewithal and latitude of a direct gubernatorial 

appointment. 

This authority must be empowered and authorized by the mutual 

consent of all responsible agencies to become deeply engaged with all these 

agencies. The authority’s over-arching responsibility will be to keep hurricanerelated safety at the forefront of public priorities. The authority will provide 

leadership, strategic vision, definition of roles and responsibilities, formalized 

avenues of communication, prioritization of funding, and coordination of 

critical construction, maintenance, and operations. 

Changes to the New Orleans area levee board structure approved by 

voters in 2006 will help streamline communications and establish a stronger 
80 THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why

technical basis for managing the levees. The ASCE Hurricane Katrina External 

Review Panel endorses this effort, which comprises a good first step until the 

appointment of the authority goes into effect.

CALL-TO-ACTION NUMBER 7:

Improve inter-agency coordination. 

There has been an historic lack of coordination between agencies at all levels: 

local, state, and federal. The only practical way to overcome this organizational 

confusion is to implement strong, sustainable mechanisms for communication, 

cooperation, and coordination. We envision that the commissioner (as identified 

in Call-to-Action Number 6) will be able to provide overall direction and make 

sure that all parties are working together. 

All agencies involved in the hurricane protection system should 

implement far better and more effective mechanisms for coordination 

and cooperation. The agencies responsible for funding must coordinate with 

and advocate for those responsible for implementation. Those responsible 

for the hurricane protection system must establish iron-clad protocols with 

those who are responsible for emergency response. Those responsible 

for maintenance of the hurricane protection system must collaborate with 

system designers and constructors to upgrade their inspection, repair, and 

operations to ensure that the system is hurricane-ready and flood-ready. 

Those responsible for operating the floodgates must take direction from those 

responsible for emergency preparedness, and close the levee penetrations 

when a hurricane threatens. 

Demand Engineering Quality

The ASCE Hurricane Katrina External Review Panel believes that the failures 

in New Orleans’s hurricane protection system constitute one of the worst 

catastrophes ever to befall this country. The flaws uncovered as a result 

of Hurricane Katrina must serve as a sobering reminder to engineers 

everywhere that their work has life-or-death implications. Whatever the 

constraints—whether related to cost, schedule, political resistance, or 

inertia—engineers must continue to uphold the highest standards of their 

profession, knowing that peoples’ lives are at stake.
THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why 81

CALL-TO-ACTION NUMBER 8:

Upgrade engineering design procedures. 

The USACE and its consultants—as well as ASCE and its members—must 

upgrade engineering design procedures, placing greater emphasis on safety, 

taking into account lessons learned from Hurricane Katrina, and incorporating 

the latest research findings and best engineering practices. The engineering 

community should review and update engineering design procedures 

for hurricane and flood protection systems to ensure that these updated 

procedures take all reasonable steps to protect the public safety, health, 

and welfare.

The USACE—and engineering research organizations around the country 

—should increase research into the design and construction of better hurricane 

protection systems. The latest technological advances should be used to 

improve the models, designs, retrofits, and maintenance of hurricane protection 

systems in New Orleans and other parts of the country.

CALL-TO-ACTION NUMBER 9

Bring in independent experts. 

ASCE has a long-standing policy that recommends independent external peer 

review for all public works projects where performance is critical to public 

safety, health, and welfare; where reliability of performance under emergency 

conditions is critical; that use innovative materials or techniques; that lack 

redundancy in design; or that have unique construction sequencing or a short/

overlapping design-construction schedule.

The ASCE Hurricane Katrina External Review Panel believes that many 

of the major deficiencies in New Orleans’s hurricane protection system could 

have been avoided if the engineering plans and designs had undergone highlevel, independent engineering review by external experts. 

Agencies responsible for design of hurricane and flood protection 

systems and other critical life-safety structures should engage independent 

experts in high-level review of every project.
82 THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why

CALL-TO-ACTION NUMBER 10:

Place safety first.

Although the conditions leading up to the New Orleans catastrophe are unique, 

the fundamental constraints placed on engineers for any project are not. Every 

project has funding and/or schedule limitations. Every project must integrate 

into the natural and man-made environment. Every major project has political 

ramifications. 

In the face of pressure to save money or to make up time, engineers 

must remain strong and hold true to the requirements of the profession’s 

canon of ethics, never compromising the safety of the public. Organizations 

must be structured to enable, not to inhibit, this focus on safety. Engineers 

must continually evaluate the appropriateness of design criteria. They must 

always consider how the performance of individual components affects the 

overall performance of a system. 

The first Fundamental Canon of ASCE’s Code of Ethics states that 

“Engineers shall hold paramount the safety, health, and welfare of the 

public....” This canon must be the guiding principle for rebuilding the hurricane 

protection system in New Orleans. And it must be applied with equal rigor 

to every aspect of an engineer’s work—in New Orleans, in America, and 

throughout the world. ASCE, working in partnership with the USACE and 

other engineering organizations, should reinforce the need to place the 

safety, health, and welfare of the public first, and should communicate 

that public safety must always be the highest priority.
83

ACKNOWLEDGEMENTS

The ASCE Hurricane Katrina External Review Panel would like to express its heartfelt 

gratitude to Sybil E. Hatch, P.E., M.ASCE, and her colleagues at Convey, for their 

outstanding efforts at pulling together the manuscript, figures, and photographs that 

compose this report. Sybil’s considerable writing and editing skills were invaluable in 

helping us better explain what went wrong with the New Orleans hurricane protection 

system, and why.

The ASCE Hurricane Katrina External Review Panel would also like to sincerely 

thank the members of ASCE staff who provided timely and effective support during 

this effort, especially Lawrence H. Roth, P.E., G.E., ASCE’s Deputy Executive Director, 

for his leadership. In addition, John E. Durrant, P.E., M.ASCE, Charles V. (Casey) Dinges 

IV, Aff.M.ASCE, Jane Howell, and Joan Buhrman made themselves available day and 

night to assist in our review effort, manage logistics, and deftly handle extensive 

media relations. Our work would not have been possible without their dedicated help 

and their excellent contributions.

Finally, and most importantly, the ASCE Hurricane Katrina External Review 

Panel extends its deep appreciation to the U.S. Army Corps of Engineers (USACE) and 

to the Chief of Engineers, Lieutenant General Carl A. Strock, P.E., for their decision to 

seek a comprehensive, real-time review of the work of the Interagency Performance 

Evaluation Taskforce (IPET). It took considerable courage to call for detailed external 

peer review of a project with such high visibility, and USACE should be commended 

for this action. USACE should also be commended for the constructive and 

professional manner in which our review was engaged. In particular we thank Donald 

L. Basham, P.E., USACE Chief of Engineering and Construction, Lewis E. (Ed) Link, 

Ph.D., IPET Project Director, and John J. Jaeger, Ph.D., P.E., IPET Technical Director, 

for establishing a sound technical framework for this enormous effort as well as for 

creating an atmosphere of collegiality and cooperation. 

The nation owes a debt of gratitude to the dedicated efforts of the more than 

150 engineers and scientists who labored long and hard to provide meaningful input 

into rebuilding the New Orleans and Southeast Louisiana hurricane protection system. 

It was indeed an honor for each of us to be associated with such a comprehensive 

evaluation and analysis leading to useful findings and critical lessons learned. ASCE and 

the ASCE Hurricane Katrina External Review Panel greatly appreciate the opportunity 

to be of service to USACE and to the nation.
84 THE NEW ORLEANS HURRICANE PROTECTION SYSTEM: What Went Wrong And Why

CREDITS

Cover Background: The Dallas Morning News/Smiley N. Pool; Inset top left: Photo by 

Ted Jackson © 2006 The Times-Picayune; Inset top right: Photo by Ellis Lucia © 2006 

The Times-Picayune; Inset bottom left: The Dallas Morning News/Smiley N. Pool; 

Inset bottom right: Photo by David Grunfeld © 2006 The Times-Picayune.

Title Page Satellite view of Hurricane Katrina: courtesy of NASA, found at Visible 

Earth (http://visibleearth.nasa.gov/)

Chapter 2 Figures 2.1, 2.4, and 2.5: base photos courtesy of NASA, found at Visible 

Earth (http://visibleearth.nasa.gov/); Figure 2.2: original public domain photo by 

FEMA edited, displayed, and delivered by IllinoisPhoto.com. The photographer and 

agencies that provided this photo, as well as any subjects depicted in this photo, are 

not endorsing any products, services, conclusions, or findings contained within this 

report; Figure 2.3: courtesy of the University of Texas Libraries, The University of 

Texas at Austin; Figure 2.7: The Dallas Morning News/Irwin Thompson.

Chapter 3 Figure 3.1: courtesy of University of Wisconsin-CIMSS; Figure 3.2:

courtesy of Dr. Hassan Mashriqui, Louisiana State University Hurricane Center; 

Figure 3.3: courtesy of National Oceanic & Atmospheric Administration; Figure 3.4: 

courtesy of the Louisiana State University Hurricane Public Health Center; Figure 3.5:

courtesy of the U.S. Army Corps of Engineers Interagency Performance Evaluation 

Task Force.

Chapter 4 Figures 4.1, 4.2, 4.3, 4.4, and 4.5: courtesy of the U.S. Army Corps of 

Engineers Interagency Performance Evaluation Task Force.

Chapter 5 Figure 5.1: courtesy of Don McCrosky, Entergy; Figure 5.2: courtesy 

of Robert G. Traver, Ph.D., P.E., D.WRE, Associate Professor, Villanova University; 

Figure 5.3: base photo courtesy of NASA, found at Visible Earth (http://visibleearth.

nasa.gov/); Figures 5.4, 5.5, 5.6, and 5.7: courtesy of U.S. Army Corps of Engineers; 

Figures 5.8, 5.10, and 5.11: courtesy of the U.S. Army Corps of Engineers 

Interagency Performance Evaluation Task Force; Figure 5.9: AP Photo/David J. Phillip.

Chapter 6 Figure 6.1 top: John Pendygraft, St. Petersburg Times/WpN; Figure 6.1 

bottom left: Photo by Chris Granger © 2006 The Times-Picayune; Figures 6.1 bottom 

right and 6.11 top: Photo by David Grunfeld © 2006 The Times-Picayune; Figure 6.2:

AP Photo/Bill Haber; Figure 6.3: The Dallas Morning News/Smiley N. Pool;

Figures 6.4 and 6.5 left: Robert G. Traver, Ph.D., P.E., D.WRE, Associate Professor, 

Villanova University; Figures 6.5 right, 6.8 bottom, and 6.12: Photo by Chris Granger 

© 2006 The Times-Picayune; Figure 6.6 top: The Dallas Morning News/Tom Fox; 

Figure 6.6 bottom: Photo by Eliot Kamenitz © 2006 The Times-Picayune; Figure 

6.7: U.S. Army Corps of Engineers Interagency Performance Evaluation Task Force; 

Figure 6.8 top, and 6.10: Photo by John McCusker © 2006 The Times-Picayune; 

Figure 6.9: Photo by Ellis Lucia © 2006 The Times-Picayune; Figure 6.11 bottom: AP 

Photo/Dave Martin; Figure 6.13: Photo by Bob Marshall © 2006 The Times-Picayune.

Chapter 7 Figures 7.2, 7.6, 7.9, 7.11, and 7.12: U.S. Army Corps of Engineers 

Interagency Performance Evaluation Task Force.

Chapter 8 Figure 8.1: Robert B. Gilbert, Ph.D., P.E., M.ASCE, ASCE/ERP; Figure 

8.2: Google EarthTM mapping service; Figure 8.3 top: Peter G. Nicholson, Ph.D., P.E., 

F.ASCE, ASCE/ERP & University of Hawaii; Figure 8.3 bottom: Photograph by Joseph 

Wartman, Drexel University; Figure 8.4: U.S. Army Corps of Engineers Interagency 

Performance Evaluation Task Force.