Order Code RS22238
Updated September 8, 2005
CRS Report for Congress
Received through the CRS Web
New Orleans Levees and Floodwalls:
Hurricane Damage Protection
Nicole T. Carter
Analyst in Environmental Policy
Resources, Science, and Industry Division
Summary
Hurricane Katrina’s storm surge breached floodwalls and levees surrounding New
Orleans, causing widespread inundation and significant damage and hampering rescue
and recovery efforts. Flooding from precipitation and storm surges flowing over levees
and floodwalls was anticipated because the hurricane’s intensity (Category 4) exceeded
the structures’ design (Category 3); however, structural failure of the floodwalls and
consequent flooding were uncertain. The factors contributing to breaches are the subject
of conjecture and likely will be the subject of investigation. The breaches occurred at
the
Lake Pontchartrain and Vicinity Project being constructed by the U.S. Army Corps
of Engineers and maintained by local levee districts. Those observers questioning why
infrastructure providing a greater level of hurricane protection was not available are
countered by those arguing that structural protections carry their own risks. This report
will be updated as needed to track significant developments.
Flooding in New Orleans by Hurricane Katrina was expected, but the extent of
inundation was uncertain. Because of the city’s topography — much of it below sea-level
and lacking natural drainage — precipitation often causes local flooding which is
controlled by a network of canals and pumps. Flooding due to overtopping of levees and
floodwalls was predicted for a storm stronger than a Category 3 hurricane; that is, based
on Katrina’s Category 4 strength, it was expected that storm surge would cause some
water to flow over the levees and floodwalls, which were designed to provide protection
from a Category 3 hurricane.1
Four breaches along three New Orleans canals occurred as the result of Katrina.
Failure is an inherent risk of any flood control structure and can result in catastrophic
damage. Breaches represent a structural failure, which is distinct from overtopping of
levees and floodwalls. Both breaches and overtopping may occur as design is exceeded.
1 Storm Categories are based on the Saffir-Simpson Hurricane Scale of 1-5, with Category 4
storms having 131-155 mile per hour (mph) winds and a 13- to 18-foot storm surge and Category
5 storms having winds exceeding 155 mph and surges above 18 feet.
Congressional Research Service {
The Library of Congress
CRS-2
The factors contributing to the multiple breaches in New Orleans are the subject of
speculation, and likely will be the subject of investigations and congressional interest.
This report focuses on the city’s levee and floodwall infrastructure; it does not cover
emergency planning, mitigation, response, and recovery efforts or other parts of the nation
affected by Hurricane Katrina. This report is divided into three sections. The first
provides a primer on the levee and floodwall system surrounding New Orleans, with
particular attention to the federal projects and the challenges of protecting the city. The
second section focuses on the floodwalls where the breaches occurred: the
Lake
Pontchartrain and Vicinity Project. The third section discusses providing coastal
Louisiana with Category 4 and 5 hurricane protection.
New Orleans Storm and Flood Damage Reduction Infrastructure
New Orleans faces flooding threats from the Mississippi River, coastal storms, and
intense precipitation; the system of levees and floodwalls around the city is designed to
provide a certain level of protection from these threats.2 The complementary system of
pumps and canals is designed to remove water trapped in the city. The storm damage
reduction infrastructure around New Orleans consists of levees and floodwalls, and
represents a combination of federal and local investments and responsibilities. Levees are
broad, earthen structures, while floodwalls are concrete and steel walls, built atop a levee
or in place of a levee. Floodwalls are often used in urban areas because they require less
land than levees. The floodwalls in New Orleans generally are 6 to 10 feet tall and a foot
wide at the top and two feet wide at the base, and they stand on earthen foundations.
Federal Projects. Most of the nation’s flood and storm damage reduction
infrastructure is maintained by local governments and local levee districts; some of the
infrastructure is locally built, while other projects are built by the federal government.
The principal federal agency responsible for constructing flood, storm, and shore
protection infrastructure is the U.S. Army Corps of Engineers (Corps).3
Congress has authorized the Corps to construct five hurricane protection projects for
coastal Louisiana to provide protection from a Category 3 storm; the two projects most
relevant to central New Orleans are the
Lake Pontchartrain and Vicinity Hurricane
Protection Project and the
West Bank and Vicinity Hurricane Protection Project. In
1999, the House Committee on Transportation and Infrastructure authorized, via a
Committee Resolution, a
Hurricane Protection Louisiana study to investigate providing
Category 4 and 5 hurricane protection for coastal Louisiana that would encompass all five
of the previously-authorized projects. Congress also authorized the
Southeast Louisiana
Urban Flood Control Project for pumping and canal improvements for Orleans,
Jefferson, and St. Tammany parishes.
In addition, Congress has authorized a study of restoring and protecting coastal
Louisiana’s wetlands, which can buffer surges produced by some storms. Significant
2 For a map of this system produced by the
New Orleans Times-Picayune, see
[http://www.nola.com/hurricane/popup/nolalevees_jpg.html], visited on Sept. 6, 2005.
3 For more on the Corps’ water resources activities, see CRS Report RS20866,
The Civil Works
Program of the Army Corps of Engineers: A Primer, by Nicole T. Carter and Betsy A. Cody.
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acreage of coastal Louisiana’s wetlands have been converted to open water. This
conversion is the result of many factors; some are human-induced, while others are
natural processes. The most commonly cited human factors are (a) existing flood control
and navigation improvements of the Mississippi River, which have reduced the natural
processes of sediment nourishment of the coast, and (b) wetlands fragmentation and
erosion from the oil and gas production infrastructure along Louisiana’s coast, including
the construction of numerous canals. The pending House and Senate versions of a Water
Resources Development Act (WRDA) of 2005 (H.R. 2864 and S. 728) would authorize
an initial $1.1 billion in efforts to restore these wetlands. For more information on coastal
Louisiana wetlands loss and restoration, see CRS Report RL32673,
Coastal Louisiana:
Attempting to Restore an Ecosystem, by Jeffrey Zinn. For more information on WRDA
legislation, see CRS Issue Brief IB10133,
Water Resources Development Act (WRDA):
Army Corps of Engineers Authorization Issues in the 109th Congress, coordinated by
Nicole T. Carter.
Challenge of New Orleans Hurricane Protection. Protecting New Orleans
has been an increasingly difficult task. First, the city has become increasingly vulnerable.
Land in the city has subsided; barrier islands and wetlands buffering coastal Louisiana
have been disappearing; and sea levels have risen. These factors have raised concerns
about the infrastructure’s ability to provide Category 3 protection. According to the
project justification sheet included in the Administration’s Corps FY2006 budget request,
“the project was initially designed in the 1960s, and a reanalysis was performed for part
of the project in the mid-1980s. Continuing coastal land loss and settlement of land in the
project may have impacted the ability of the project to withstand the design storm.”4
Second, the greater New Orleans metropolitan area has been experiencing population and
rapid economic growth resulting in greater numbers of people and more infrastructure and
investments exposed to storm threats. The challenge of protecting New Orleans could
become even greater. According to some scientists, higher sea surface temperatures may
result in increased hurricane intensity.5 Climate change concerns and other factors have
raised questions about whether both estimates of the likelihood of hurricanes of various
strengths and past decisions based on these estimates need to be re-evaluated.
Lake Pontchartrain and Vicinity Project
Breaches and Flooding. Some parts of New Orleans were flooded by Hurricane
Katrina’s precipitation and overtopping of levees, but the major source of flood waters
appears to have been the floodwall breaches of the Lake Pontchartrain and Vicinity
Project. The immediate and underlying causes of these breaches are the subject of much
4 U.S. Army Corps of Engineers,
Fiscal Year 2006, Mississippi Valley Division, visited Sept. 3,
2005, available at
[http://www.usace.army.mil/inet/functions/cw/cecwb/just_states06/mvd.pdf].
5 For example, see Intergovernmental Panel on Climate Change,
Climate Change 2001: Working
Group II: Impacts, Adaptation and Vulnerability, visited on Sept. 3, 2005, available at
[http://www.grida.no/climate/ipcc_tar/wg2/029.htm], or T.R. Knutson and R.E. Tuleya, “Impact
of CO2-Induced Warming on Simulated Hurricane Intensity and Precipitation: Sensitivity to the
Choice of Climate Model and Convective Parameterization,”
Journal of Climate, 15 Sept. 2004,
17 (18), available at [http://www.gfdl.noaa.gov/reference/bibliography/2004/tk0401.pdf].
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conjecture, ranging from exceeded design to poor design, construction, or maintenance,
to incomplete construction arising from limited Corps appropriations.
According to the Corps,6 the breaches were at floodwalls along three canals. The
17th Street Canal breach was at a levee-floodwall combination; the breach reached 450
feet in length. According to the Corps, “it’s believed that the force of the water
overtopped the floodwall and scoured the structure from behind and then moved the levee
wall horizontally.” The Industrial Canal floodwall had two breaches — a 100-foot
breach, and a 500-foot breach. The London Street floodwall had a 300-foot breach. The
Corps continues to work on repairing the breaches. The Corps noted that other levees and
floodwalls were being monitored for potential breaches.
Removing flood waters from the city presents multiple challenges. First, repair of
the 17th Street Canal is important because the canal is the main route for moving water out
of the city once pumps are running. Second, most of the city’s pumping facilities are not
operational. Estimates for removing flood waters range from 36 days to more than two
months. The city’s saturated soil may delay subsequent rebuilding.
Project History and Appropriations. The Lake Pontchartrain and Vicinity
Project was authorized by Congress originally in the Flood Control Act of 1965, with
subsequent modifications in other legislation. The project, which has some completed
segments and others under construction, is intended to reduce hurricane damages from
surges entering Lake Pontchartrain from Lake Borgne through natural tidal passes. The
total cost for the Lake Pontchartrain and Vicinity project is $738 million, with the federal
responsibility $528 million.7 Federal allocations reached $458 million (87% of the federal
responsibility) with the amount appropriated for FY2005. A Corps project fact sheet
stated that the project’s FY2005 appropriations would be “insufficient to fund new
construction contracts,” and that the Corps had the capability to use $20 million.8 The
fact sheet also stated:
In Orleans Parish, two major pump stations are threatened by hurricane storm surges.
Major contracts need to be awarded to provide fronting protection for them. Also,
several levees have settled and need to be raised to provide the design protection. The
current funding shortfalls in fiscal year 2005 and fiscal year 2006 will prevent the
Corps from addressing these pressing needs.
6 This Sept. 1, 2005 document is available at
[http://www.mvd.usace.army.mil/hurricane/news/11_pm_1_sept_corps_response_to_katrina_
recovery_efforts.doc], visited on Sept. 3, 2005.
7 Most Corps storm damage reduction construction projects are cost-shared 65% federal and 35%
non-federal. Operation and maintenance of these projects generally is 100% a non-federal
responsibility.
8 U.S. Army Corps of Engineers,
Project Fact Sheet, Lake Pontchartrain, LA. and Vicinity
Hurricane Protection Project (May 23, 2005) available at
[http://www.mvn.usace.army.mil/pao/response/HURPROJ.asp?prj=lkpon1], visited Sept. 3, 2005.
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Funding for individual Corps projects varies annually for multiple reasons.9 Funding
for the Lake Pontchartrain project has declined from 1996 through 2005. During that
period, the Clinton and Bush Administrations requested $58 million for the project;
Congress appropriated approximately $70 million more than requested. A funding trend
for the Corps’ two other New Orleans projects, however, is less evident. The funding
history for the Lake Pontchartrain hurricane protection, West Bank hurricane protection,
and Southeast Louisiana Urban Flood Control projects and for the total Corps civil works
program is provided in
Table 1.
Although the Corps civil works appropriations have increased in the last decade,
competition for funds among projects has been tight, with many projects that historically
received appropriations not being included in recent budget requests. Federal investments
in water resources infrastructure remains considerably lower than levels of the 1950s and
1960s,10 and the Corps has warned of problems associated with aging infrastructure and
a backlog of construction activities. (For more information on Corps appropriations, see
CRS Report RL32852,
Energy and Water Development FY2006 Appropriations,
coordinated by Carl E. Behrens.)
Table 1. Requests and Appropriations for Selected New Orleans
Projects and Corps Civil Works
Fiscal Year
Lake
West Bank and
Southeast
Total Corps
Pontchartrain
Vicinity
Louisiana
Civil Works
(in thousands)
(in thousands)
(in thousands)
(in billions)
Req.
App.
Req.
App.
Req.
App.
Req.
App.
2005
3,937
5,719
37,000
30,000
30,000
36,500
4.12
4.71
2004
3,000
5,500
35,000
28,500
16,500
34,400
4.19
4.57
2003
4,900
7,000
5,000
9,000
20,083
50,000
4.29
4.63
2002
7,500
14,250
12,000
12,500
51,908
60,000
3.90
4.49
2001
3,100
10,000
8,065
8,065
47,260
69,000
4.06
4.54
2000
11,887
16,887
7,000
15,070
47,066
47,066
3.91
4.14
1999
5,676
16,000
3,936
7,000
15,278
75,000
3.24
3.96
1998
6,448
22,920
2,385
2,385
6,440
47,000
3.70
4.06
1997
4,025
17,025
0
1,500
10,000
17,500
3.29
3.50
1996
7,848
13,348
NA
NA
0
2,000
3.34
3.20
Source: Compiled by CRS from Energy and Water Appropriations conference reports.
Category 4 and 5 Protection
In August 2002, the Corps completed a reconnaissance study of whether to
strengthen coastal Louisiana’s hurricane damage reduction projects, including the New
Orleans projects, to protect against Category 4 and 5 storms. If implemented, coastal
9 For a description of some reasons for yearly funding variations and the Corps’ response to
inquiries about New Orleans project funding, see an Corps Press Release from Sept. 3, 2005,
available at [http://www.usace.army.mil/PA-09-01.pdf], visited on Sept. 8, 2005.
10 For example, annual appropriations for the Corps’ construction account fell from a $4 billion
average in the mid-1960s (in 1999 dollars) to a $1.5 billion average for 1996 through 2005.
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Louisiana would have the only Category 5 protection system in the country. The next step
in the Corps’ project development process is a feasibility study.11 The feasibility study
for this project was estimated to cost $8 million and take at least five years; construction
would take another 10 to 20 years and $2.5 billion.12 A congressionally-added FY2005
appropriation of $100,000 for the feasibility study was to be used for completing a project
management plan and executing the cost share agreement with the local sponsor of the
study. The study was not included in the President’s FY2006 request. According to a
Corps document, $500,000 for FY2006 is required to initiate work on the feasibility
study.13 The House report (H.Rept. 109-86) for the pending Energy and Water
Development Appropriations Act for FY2006 (H.R. 2419) did not include funds for this
study; the Senate report (S.Rept. 109-84) included $250,000.
As part of a feasibility study, the Corps analyzes the national benefits and costs of
a storm damage reduction project. How these evaluations are performed and the costs and
benefits that are included has long been debated. For example, structures in New Orleans
area generally were not built to withstand Category 5 winds; therefore, providing
Category 5 protection from storm surges will not protect the city and its structures from
a Category 5 hurricane’s winds and other threats. These analyses also take into account
the likelihood of various storm events happening.
Hurricane Katrina has resulted in some questioning why a Category 4 or 5 hurricane
storm damage system was not already in place for New Orleans, and whether it should
be part of the rebuilding effort. Others are supporting more emphasis on restoration of
coastal wetlands to improve storm damage protection. Others are raising concerns about
the extent of rebuilding that should take place considering the city’s hurricane and
flooding vulnerability. They are concerned that higher levees and floodwalls may provide
a false sense of security and continued risk of catastrophic failure. Decisions on what type
and level of hurricane protection to provide New Orleans and other coastal areas in the
future, as well as factors contributing to Katrina’s damages (Category 3 levees and
floodwalls, and design, construction, maintenance, and appropriations for that
infrastructure) likely will be the subject of congressional oversight.
11 For information on the Corps project development process, see CRS Report RL32064,
Army
Corps of Engineers Water Resources Activities: Authorization and Appropriations, by Nicole T.
Carter and H. Steven Hughes.
12 U.S. Army Corps of Engineers, New Orleans District,
Riverside, September-October 2004,
visited on Sept. 3, 2005, available at
[http://www.mvn.usace.army.mil/pao/Riverside/Sept-Oct_04_Riv.pdf]; and A.C. Revkin, and C.
Drew, “Engineers’ warnings and pleas for money went unheeded,”
The New York Times, Sept.
2, 2005.
13 The March 2005 fact sheet, visited on Sept. 3, 2005, is available at
[http://www.mvn.usace.army.mil/pd/Funding_Programs/Current/GI_HurrProt_FY06.pdf].