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{{Short description|Engineering failures in Louisiana during Hurricane Katrina}}
[[File:London Avenue Bridge Memorial.jpg|thumb]]
On Monday, August 29, 2005, there were over 50 failures of the [[levee]]s and [[flood wall]]s protecting [[New Orleans, Louisiana]], and its suburbs following passage of [[Hurricane Katrina]]. The failures caused flooding in 80% of New Orleans and all of [[St. Bernard Parish, Louisiana|St. Bernard Parish]]. In New Orleans alone, 134,000 housing units — 70% of all occupied units — suffered damage from Hurricane Katrina and the subsequent flooding.<ref>{{Cite web |last=Plyer |first=Allison |date=August 26, 2016 |title=Facts for Features: Katrina Impact |url=https://www.datacenterresearch.org/data-resources/katrina/facts-for-impact/ |website=The Data Center}}</ref>
When Katrina's storm surge arrived, the hurricane protection system, authorized by Congress [[Flood Control Act of 1965| forty years earlier]], was between 60–90% complete.<ref name="gao.gov">{{Cite web|url=https://levees.org/2/wp-content/uploads/2020/02/2005-GAO-report-Testimony-Before-the-Subcommittee-on-Energy-and-Water-Development-Committee-on-Appropriations-House-of-Representatives.pdf | title= Army Corps of Engineers; Lake Pontchartrain and Vicinity Hurricane Protection Project |date=2005-09-28|access-date=2021-09-20}}</ref> Responsibility for the design and construction of the levee system belongs to the [[United States Army Corps of Engineers]], while responsibility for maintenance belongs to the local levee districts. Six major investigations were conducted by civil engineers and other experts in an attempt to identify the underlying reasons for the failure of the federal flood protection system. All concurred that the primary cause of the flooding was inadequate design and construction by the Army Corps of Engineers.<ref>Robertson, Campbell. {{Cite web|url= https://www.nytimes.com/2015/05/24/us/decade-after-katrina-pointing-finger-more-firmly-at-army-corps.html |title= Decade After Katrina, Pointing Finger More Firmly at Army Corps |date=2015-05-23|website=New York Times|access-date=2016-10-20}}</ref> In April 2007, the [[American Society of Civil Engineers]] termed the flooding of New Orleans as "the worst engineering catastrophe in US History."<ref name="ACSE2007"/>
On January 4, 2023, the National Hurricane Center (NHC) updated the Katrina fatality data based on Rappaport (2014). The new toll reduced the number by about one quarter from an estimated 1,833 to 1,392.<ref>{{Cite web |last1=Knabb |first1=Richard D. |last2=Rhome |first2=Jamie R. |last3=Brown |first3=Daniel P. |date=January 4, 2023 |title=Tropical Cyclone Report, Hurricane Katrina 23-30 August 2005 |url=https://www.nhc.noaa.gov/data/tcr/AL122005_Katrina.pdf |website=}}</ref> The Rappaport analysis wrote that the 2005 storm “…stands apart not just for the enormity of the losses, but for the ways in which most of the deaths occurred.”<ref>{{Cite journal |last=Rappaport |first=Edward N. |date=March 1, 2014 |title="Fatalities in the United States from Atlantic Tropical Cyclones: New Data and Interpretation," Bulletin of the American Meteorological Society, Vol 95, Issue 3. |journal=Bulletin of the American Meteorological Society |volume=95 |issue=3 |pages=341–346 |doi=10.1175/BAMS-D-12-00074.1 |s2cid=120480791 |doi-access=free }}</ref> The same NHC report also revised the total damage estimate keeping Hurricane Katrina as the costliest storm ever––$190 billion according to NOAA’s National Centers for Environmental Information.<ref>{{Cite news |last=Schleifstein |first=Mark |date=January 14, 2023 |title="How many people died in Hurricane Katrina? Toll reduce 17 years later" |work=The Advocate |url=https://www.nola.com/news/hurricane/how-many-people-died-in-katrina-toll-reduced-17-years-on/article_e3009e46-91ed-11ed-8f2a-a7b11e1e8d34.html}}</ref>
There were six major breaches in the city of [[New Orleans]] itself (the Orleans [[Parish (administrative division)|parish]], as compared to [[Greater New Orleans]] which comprises eight parishes):
#Three major breaches occurred on the Inner Harbor Navigation Canal (locally known as the [[Industrial Canal]]). A breach on the northeast side near the junction with the [[Gulf Intracoastal Waterway]] flooded [[New Orleans East]]. Two breaches on the southeast side between Florida Avenue and Claiborne Avenue combined into a single 1,000 foot wide hole that allowed stormwater to catastrophically rush into the adjacent [[Lower Ninth Ward
#On the western edge of New Orleans near Hammond Highway, a breach opened in the [[17th Street Canal]] levee. Floodwater flowed through a hole that became 450 feet wide, flooding the adjacent Lakeview neighborhood.<ref>{{Cite web |
#The [[London Avenue Canal]] in the Gentilly region, breached on both sides; on the west side near Robert E. Lee Boulevard and on the east near Mirabeau Avenue.
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==Background==
[[File:New Orleans Elevations.jpg|thumb|300px|left|Vertical cross-section of New Orleans, showing maximum levee height of 23 feet (7 m) at the Mississippi River on the left and 17.5 feet (5 m) at Lake Pontchartrain on the right]]
{{See also|Drainage in New Orleans|Hurricane preparedness
The original residents of [[French Quarter|New Orleans]] settled on the high ground along the Mississippi River. Later developments eventually extended to nearby Lake Pontchartrain, built upon fill to bring them above the average lake level. Navigable commercial waterways extended from the lake to downtown. After 1940, the state decided to close those waterways following the completion of a new [[Industrial Canal]] for waterborne commerce, which opened in 1923.<ref>{{Cite web |last=DeGregorio |first=Jen |title=Changing with the times |url=https://www.nola.com/news/article_8ed918a1-fdba-58dc-97a0-8ba8d93e356f.html |access-date=2022-11-17 |website=NOLA.com |date=January 13, 2008 |language=en}}</ref> Closure of the waterways resulted in a drastic lowering of the water table by the city's drainage system, causing some areas to settle by up to <span style="white-space:nowrap">8 feet (2 m)</span> due to the compacting and desiccation of the underlying organic soils.
After the [[Great Mississippi Flood of 1927]], [[United States Congress]] passed the [[Flood Control Act of 1928]] which authorized the Corps of Engineers to design and construct flood control structures, along with levees, on the Mississippi River to protect populated areas from floods. It also affirmed the principle of local participation in federally funded projects but acknowledged that the $292 million already spent by local interests was sufficient to cover local participatory costs.<ref>[http://www.mvd.usace.army.mil/mrc/history/AppendixE.htm Flood Control Act of 1928 on Mississippi Valley Division of USACE website] {{webarchive|url=https://web.archive.org/web/20090109031739/http://www.mvd.usace.army.mil/mrc/history/AppendixE.htm |date=2009-01-09 }}</ref> It is instructive to note that, in addition, sovereign immunity was given to the Corps of Engineers under Section 3 of the Flood Control Act of 1928, which states “no liability of any kind would attach or rest upon the United States for any damage from or by floods or flood waters at any place, provided that if on any stretch of the banks of the Mississippi River it was impracticable to construct levees.” 33 U.S.C. § 702c. Section 702c is sometimes referred as “Section 3 of the act,” based on where it appears in the Public law.▼
▲After the [[Great Mississippi Flood of 1927]], [[United States Congress]] passed the [[Flood Control Act of 1928]] which authorized the Corps of Engineers to design and construct flood control structures, along with levees, on the Mississippi River to protect populated areas from floods. It also affirmed the principle of local participation in federally funded projects but acknowledged that the $292 million already spent by local interests was sufficient to cover local participatory costs.<ref>
[[File:Authorized Plan of Protection.jpg|thumb|[[:File:Authorized Plan of Protection.jpg|Authorized Plan of Protection for Lake Pontchartrain and Vicinity, Louisiana, November 1965. Map by U.S. Army Engineer District, New Orleans Corps of Engineers. Revised Dec 1970 and April 1978. ]]]]
Heavy flooding caused by [[Hurricane Betsy]] in 1965 brought concerns regarding flooding from hurricanes to the forefront. In response, the Congress passed the [[Flood Control Act of 1965]] which mandated that henceforth, the [[United States Army Corps of Engineers|Corps of Engineers]] is the agency responsible for design and construction of flood protection projects, to include those in Greater New Orleans. The local interests' role was maintenance once the projects were complete.<ref name=GAOReport>{{Cite web |url=http://www.gao.gov/new.items/d051050t.pdf |title=GAO Report on Lake Pontchartrain and Vicinity Hurricane Protection Project, September 2005 |access-date=November 25, 2008 |archive-url=https://web.archive.org/web/20110523230347/http://www.gao.gov/new.items/d051050t.pdf |archive-date=May 23, 2011 |url-status=dead }}</ref>
Also that year, Congress authorized the Lake Pontchartrain and Vicinity Hurricane Protection Project (LPVHPP) which reiterated the principle of local participation in federally funded projects. The project was initially estimated to take 13 years, but when Katrina struck in 2005, almost 40 years later, the project was only 60–90% complete with a revised projected completion date of 2015.<ref name="gao.gov"/>
On August 29, 2005, flood walls and levees catastrophically failed throughout the metro area. Some collapsed well below design thresholds (17th Street and London Avenue Canals and also the northeast breach of the Industrial Canal). Others collapsed after a brief period of overtopping (southeast breach of the Industrial Canal) caused scouring or erosion of the earthen levee walls. In April 2007, the [[American Society of Civil Engineers]]
==Levee and floodwall breaches==
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[[File:HousesPrattBehindLondonAvBreech.jpg|thumb|250px|right|Severely damaged homes in piles of sand near the upper [[London Avenue Canal]] breach]]
</ref> By 6:30 a.m. [[Central Time Zone (North America)|CDT]], levees along the Gulf Intracoastal Waterway, lining the south side of New Orleans East, overtopped and breached. <ref>Van HeerdenI. Ll.Kemp G. P. Mashriqui et al. (2006). The Failure of the New Orleans Levee System during Hurricane Katrina. Final Team Louisiana Forensics Report to Louisiana Department of Transportation and Development, December 2006. Baton Rouge, LA, USA. p 71-72</ref> The surge flooded the primarily middle to upper class Black region.
On the west edge of New Orleans, between 6 and 7:00 a.m., a monolith on the east side of the London Avenue Canal failed and allowed water over 10 feet deep into Fillmore Gardens, a mostly Black middle class neighborhood.<ref>Anderson C. Battjes J. Daniel D. Edge B. (2007) The New Orleans Hurricane Protection System: What Went Wrong and Why: A Report by the American Society of Civil Engineers External Review Panel. American Society of Civil Engineers, Reston, Virginia. p 55</ref> At about 6:30 a.m., on the western edge of the city, several monoliths failed on the mighty 17th Street Canal.<ref>Anderson C. Battjes J. Daniel D. Edge B. (2007). The New Orleans Hurricane Protection System: What Went Wrong and Why: A Report by the American Society of Civil Engineers External Review Panel. American Society of Civil Engineers, Reston, Virginia. p 47</ref> A torrent of water blasted into Lakeview, a mainly white middle class neighborhood of homeowners.<ref>Anderson C. Battjes J. Daniel D. Edge B. (2007). The New Orleans Hurricane Protection System: What Went Wrong and Why: A Report by the American Society of Civil Engineers External Review Panel. American Society of Civil Engineers, Reston, Virginia. p 26</ref> Local fire officials reported the breach.<ref>{{Cite news |last=Hoss |first=Mike |date=June 20, 2006 |title=Firefighters share their story, video surrounding breach at 17th Street Canal |work=4WWL Eyewitness News}}</ref> An estimated 66% to 75% of the city was now under water. The Duncan and Bonnabel Pumping Stations were also reported to have suffered roof damage, and were non-functional.<ref>Staff Writer. "Timeline: Who Knew When the Levees Broke." National Public Radio. February 10, 2006.</ref>
At approximately 7:45 a.m. [[Central Time Zone (North America)|CDT]], a much larger second hole opened up in the Industrial Canal just south of the initial breach. Floodwaters from the two breaches combined to submerge the entire historic Lower Ninth Ward in over 10 feet of water. Between 7 and 8:00 a.m., the west side of the London Avenue Canal breached, in addition to the east side, and flooded the adjacent mixed-race neighborhood of homeowners.<ref> Anderson C. Battjes J. Daniel D. Edge B. (2007). The New Orleans Hurricane Protection System: What Went Wrong and Why: A Report by the American Society of Civil Engineers External Review Panel. American Society of Civil Engineers, Reston, Virginia. p 55</ref>
The
In September 2022, the Associated Press issued a style guide change to Katrina stating that reporters when writing about the storm in New Orleans should note that “…levee failures played a major role in the devastation in New Orleans. In some stories, that can be as simple as including a phrase about Hurricane Katrina’s catastrophic levee failures and flooding….”<ref>{{Cite web |last=The Associated Press |date=September 27, 2022 |title="Hurricane Topical Guide". AP Stylebook |url=https://apstylebook.com/hurricane-ian-test}}</ref>
==Investigations==
===Levee investigations===
In the ten years following Katrina, over a dozen investigations were conducted. There was no federally ordered independent commission like those ordered after the September 11 terrorist attacks and after the BP Oil Spill in the Gulf. The only federally ordered study was convened and managed by the Army Corps of Engineers, the federal agency responsible for the flood protection's performance. A major independent study was conducted by the University of California at Berkeley.<ref>
The primary mechanisms of failure at the 17th Street Canal, London Avenue Canal and Industrial Canal (east side north) were improper design of the canal floodwalls.<ref>{{Cite web |url=http://www.dotd.louisiana.gov/administration/teamlouisiana/ |title=La DOTD - Team Louisiana |access-date=October 9, 2007 |archive-date=August 15, 2007 |archive-url=https://web.archive.org/web/20070815202550/http://www.dotd.louisiana.gov/administration/TeamLouisiana/ |url-status=dead }}</ref> The failure mechanism for the Industrial Canal (east side south and west side) was overtopping of levees and floodwalls by the storm surge. The primary mechanism of failure for levees protecting eastern New Orleans was the existence of sand in 10% of places instead of thick Louisiana clay. The primary mechanism of failure for the levees protecting St. Bernard Parish was overtopping due to negligent maintenance<ref>{{Cite web|url=
A June 2007 report by the [[American Society of Civil Engineers]] in peer review panel concluded that the flooding in the Lakeview neighborhood (from the 17th Street Canal) and the Gentilly neighborhood (from the London Avenue Canal) was due to two engineering oversights.
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The Federal study was initiated in October 2005, by Lt. Gen. Carl Strock, [[Chief of Engineers]] and the Commander of the Corps of Engineers; he established the Interagency Performance Evaluation Task Force (IPET) to "provide credible and objective scientific and engineering answers to fundamental questions about the performance of the hurricane protection and flood damage reduction system in the New Orleans metropolitan area.<ref name=IPET>{{Cite web |url=https://ipet.wes.army.mil/NOHPP/_Post-Katrina/(IPET)%20Interagency%20Performance%20Evaluation%20TaskForce/Reports/IPET%20Final%20Report/Volume%20I/IPET%20Vol%20I%20Final%20Draft_Jun08.pdf |title=IPET Final Draft Report |access-date=2008-11-25 |archive-url=https://web.archive.org/web/20110722185115/https://ipet.wes.army.mil/NOHPP/_Post-Katrina/(IPET)%20Interagency%20Performance%20Evaluation%20TaskForce/Reports/IPET%20Final%20Report/Volume%20I/IPET%20Vol%20I%20Final%20Draft_Jun08.pdf |archive-date=2011-07-22 |url-status=dead }}</ref> IPET consisted of independent and recognized experts from the Universities of [[University of Maryland, College Park|Maryland]], [[University of Florida|Florida]], [[University of Notre Dame|Notre Dame]], and [[Virginia Polytechnic Institute]], the [[National Oceanic and Atmospheric Administration]], the [[South Florida Water Management District]], Harris County Flood Control District (Houston, TX), the [[United States Department of Agriculture]], and the [[United States Bureau of Reclamation]] as well as those from USACE.<ref name=IPET />
IPET's final findings indicated that, {{blockquote|With the exception of four foundation design failures, all of the major breaches were caused by overtopping and subsequent erosion. Reduced protective elevations increased the amount of overtopping, erosion, and subsequent flooding, particularly in Orleans East. The structures that ultimately breached performed as designed, providing protection until overtopping occurred and then becoming vulnerable to catastrophic breaching. The levee-floodwall designs for the 17th Street and London Avenue Outfall Canals and the northeast breach of the IHNC were inadequate due to steel sheet-pilings driven to depths that were too shallow. In four cases the structures failed catastrophically prior to water reaching design elevations. A significant number of structures that were subjected to water levels beyond their design limits performed well. Typically, in the case of floodwalls, they represented more conservative design assumptions and, for levees, use of higher quality, less erodible materials.<ref name=IPET /><ref>
===Criticism of the IPET Federal Investigation===
The credibility of the IPET was also challenged in a 42-page letter to the American Society of Civil Engineers (ASCE) submitted by Dr. Ray M. Seed, co-chair of the ILIT study. Dr. Seed described an early intentional plan by the Corps of Engineers to hide their mistakes in the New Orleans flooding after Katrina and to intimidate anyone who tried to intervene. All of this was done with the help and the complicity of some at the ASCE, according to Dr. Seed.<ref>[https://web.archive.org/web/20120323155056/http://www.lasce.org/documents/RaySeedsLetter.pdf Dr. Ray Seed's letter to ASCE.] hosted at ''web.archive.org''. Retrieved 29 August 2015.</ref>
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A report released in August 2015 in the official journal of the [[World Water Council]] concluded the following:
{{blockquote|"...What is evident from the project record is that the Army Corps of Engineers recommended raising the canal floodwalls for the 17th Street Canal, but recommended gated structures at the mouths of the Orleans and London Avenue Canals because the latter plan was less expensive. The OLB convinced Congress to pass legislation that required the Corps to raise the floodwalls for all three canals. Furthermore, the Corps, in a separate attempt to limit project costs, initiated a sheet pile load test (E-99 Study), but misinterpreted the results and wrongly concluded that sheet piles needed to be driven to depths of only 17 feet (1 foot ¼ 0.3048 meters) instead of between 31 and 46 feet. That decision saved approximately US$100 million, but significantly reduced overall engineering reliability..."<ref name="auto">{{cite news | page=707 | author=J. David Rogers, G. Paul Kemp | title=Interaction between the US Army Corps of Engineers and the Orleans Levee Board preceding the drainage canal wall failures and catastrophic flooding of New Orleans in 2005 | publisher=Water Policy|year=2015 | access-date=2015-10-31|url= http://levees.org/2/wp-content/uploads/2015/11/WPOL-V17-NO4-21051.pdf
}}</ref>
}}
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Aerial evaluation revealed damage to approximately 90% of some levee systems in the east which should have protected [[St. Bernard Parish, Louisiana|St. Bernard Parish]].
[[File:17rhStCanalFloodwallKatrinaGraffitti.jpg|thumb|250px|right|Portion of the flood wall atop [[17th Street Canal]] levee, with Katrina-related graffiti. Notice cracks in the flood wall joints. Operation and maintenance are the responsibility of local levee
===National Academy of Sciences Investigation===
On October 19, 2005, [[United States Secretary of Defense|Defense Secretary]] [[Donald Rumsfeld]] announced that an independent panel of experts, under the direction of the [[United States National Academy of Sciences|National Academy of Sciences]], would convene to evaluate the performance of the New Orleans levee system, and issue a final report in eight months. The panel would study the results provided by the two existing teams of experts that had already examined the levee failures.<ref>Schleifstein, Mark. "[http://www.nola.com/newslogs/breakingtp/index.ssf?/mtlogs/nola_Times-Picayune/archives/2005_10_19.html#088443 Corps levee probe role reduced] {{Webarchive|url=https://web.archive.org/web/20080326231525/http://www.nola.com/newslogs/breakingtp/index.ssf?%2Fmtlogs%2Fnola_Times-Picayune%2Farchives%2F2005_10_19.html#088443 |date=2008-03-26 }}." ''[[Times Picayune]].'' October 19, 2005.</ref> The academy concluded that “the engineering of the levee system was not adequate. The procedures for designing and constructing hurricane protection systems will have to be improved, and the designing organizations must upgrade their engineering capabilities. The levees must be seen not as a system to protect real estate but as a set of dams to protect people. There must be independent peer reviews of future designs and construction.”<ref>{{Cite web|url=https://www.nae.edu/Publications/Bridge/EngineeringfortheThreatofNaturalDisasters/LessonsfromHurricaneKatrina.aspx|title=Lessons from Hurricane Katrina}}</ref>▼
▲On October 19, 2005, [[United States Secretary of Defense|Defense Secretary]] [[Donald Rumsfeld]] announced that an independent panel of experts, under the direction of the [[United States National Academy of Sciences|National Academy of Sciences]], would convene to evaluate the performance of the New Orleans levee system, and issue a final report in eight months. The panel would study the results provided by the two existing teams of experts that had already examined the levee failures.<ref>Schleifstein, Mark. "[http://www.nola.com/newslogs/breakingtp/index.ssf?/mtlogs/nola_Times-Picayune/archives/2005_10_19.html#088443 Corps levee probe role reduced] {{Webarchive|url=https://web.archive.org/web/20080326231525/http://www.nola.com/newslogs/breakingtp/index.ssf?%2Fmtlogs%2Fnola_Times-Picayune%2Farchives%2F2005_10_19.html#088443 |date=2008-03-26 }}." ''[[Times Picayune]].'' October 19, 2005.</ref> The academy concluded that “the engineering of the levee system was not adequate. The procedures for designing and constructing hurricane protection systems will have to be improved, and the designing organizations must upgrade their engineering capabilities. The levees must be seen not as a system to protect real estate but as a set of dams to protect people. There must be independent peer reviews of future designs and construction.”<ref>{{Cite web|url=https://
===Senate Committee hearings===▼
▲===Senate and House Committee hearings===
There were twenty (20) Senate and House Committee meetings on Hurricane Katrina between September 14, 2005 and February 2, 2006.<ref>{{Cite web |date=Feb 8, 2006 |title=Summary of Hearings on Hurricane Katrina. American Geosciences Institute. |url=https://www.agiweb.org/gap/legis109/katrina_hearings.html#oct7 |website=American Geosciences Institute}}</ref>
Preliminary investigations and evidence were presented before the [[U.S. Senate]] Committee on Homeland Security and Governmental Affairs on November 2, 2005, and generally confirmed the findings of the preliminary investigations.<ref name="senate">"[http://hsgac.senate.gov/index.cfm?Fuseaction=Hearings.Detail&HearingID=290 Hurricane Katrina: Why Did the Levees Fail?]." ''[[U.S. Senate]]'' (Hearing Report for the Committee on Homeland Security and Governmental Affairs). November 2, 2005.</ref>
On
===Corps of Engineers admits problems with design===
On April 5, 2006, months after independent investigators had demonstrated that the levee failures were not due to natural forces beyond intended design strength, Lt. Gen. Carl Strock testified before the [[United States Senate Appropriations Subcommittee on Energy and Water Development|U.S. Senate Subcommittee on Energy and Water]] that "the corps neglected to consider the possibility that floodwalls atop the 17th Street Canal levee would lurch away from their footings under significant water pressure and eat away at the earthen barriers below. We did not account for that occurring." Strock said it could be called a design failure.<ref>{{cite web | publisher = UPI | date=April 6, 2006 | url = https://levees.org/2/wp-content/uploads/2017/09/Corps-of-Engineers-admits-design-failure.pdf | title = Corps of Engineers admits design failure}}</ref> He also testified that the U.S. Army Corps of Engineers did not know of this mechanism of failure prior to August 29, 2005. The claim of ignorance is refuted by the [[National Science Foundation]] investigators hired by the [[United States Army Corps of Engineers|Army Corps of Engineers]], who point to a 1986 study (E-99 study) by the corps itself that such separations were possible in the I-wall design. Nearly two months later, on June 1, 2006, the USACE issued their first draft report which states that "the storm exceeded design criteria, but the performance was less than the design intent."<ref>{{Cite web | url=https://www.piprocessinstrumentation.com/home/article/15551376/ipet-report-on-flood-control-during-katrina. | title=IPET Report on Flood Control During Katrina | publisher = Interagency Performance Evaluation Task Force | date = June 2, 2006}}</ref> The final report was issued June 2009.
The E-99 study is addressed again in a report released in August 2015 by J. David Rogers et al., who concluded that a misinterpretation of the 1986 study occurred apparently because the Corps had draped a tarpaulin over the gap that formed between the bases of the deflecting sheet piles and the soil in which they were embedded, so they did not see the gap. The tarpaulin was there for safety and to stop water that would seep through the interlocks. Failure to include the gap in interpretation of the test results introduced unconservatism in the final designs based on these tests. It allowed the use of shorter sheet piles, and reduced overall flood protection reliability.<ref
== Replacement levees ==
Following the levee failures during Hurricane Katrina, the Bush administration ordered that the levee system be rebuilt by the US Army Corps of Engineers to protect the city from a 100-year storm.<ref>{{Cite news |last=Vergun |first=David |date=Aug 17, 2015 |title=Engineers take protecting New Orleans personally. |work=Army News Service |url=https://www.army.mil/article/153971/engineers_take_protecting_new_orleans_personally}}</ref> Gates and auxiliary pumps were added to the mouths of the three major drainage canals as well as the Inner Harbor Navigation Channel to prevent water from entering the heart of the city from Lake Pontchartrain. In addition, a surge barrier was built east of the city to prevent water from entering the city from the Gulf of Mexico. Ultimately, the system’s price tag rose to 14.5 billion dollars.<ref>{{Cite news|last=Layne|first=Nathan|date=2021-08-30|title=New Orleans' levees got a $14.5 billion upgrade. Will they hold?|language=en|work=Reuters|url=https://www.reuters.com/world/us/new-orleans-levees-got-145-billion-upgrade-will-they-hold-2021-08-30/|access-date=2021-12-03}}</ref>
The strength of [[Hurricane Ida]] on August 29, 2021––exactly 16 years later––forced a considerable amount of water towards New Orleans and the system performed as designed.<ref>{{Cite web|last=Bittle|first=Jake|date=2021-09-02|title=New Orleans's Levees Held Up This Time — But That's Not Enough|url=https://www.curbed.com/2021/09/levees-louisiana-hurricane-ida-managed-retreat.html|access-date=2021-12-03|website=Curbed|language=en-us}}</ref> The surge heights and direction of the surge was different than in Hurricane Katrina and it is noted that the mayor of New Orleans did not order a mandatory evacuation. Nonetheless, realizing that there needed to be more updates and changes, the U.S. Army Corps of Engineers requested $3.2 billion from Congress in the fall 2021 to ensure that they could continue to provide 100-year level of hurricane protection through 2073.<ref>{{Cite news|last=writer|first=MARK SCHLEIFSTEIN {{!}} Staff|title=15 years after Katrina, New Orleans levees are in the best shape ever. Experts say it's not enough.|url=https://www.nola.com/news/environment/article_80c27be8-e3e7-11ea-bbf9-1731ebdd9171.html|access-date=2021-12-03|website=NOLA.com|language=en}}</ref>
==Conspiracy theories==
[[Nation of Islam]] leader [[Louis Farrakhan]] among other public figures claimed the levees were dynamited to divert waters away from wealthy white areas. The conspiracy theory reached a [[United States House of Representatives]] committee investigating Katrina when a New Orleans community activist made the claim. According to the ''[[New Orleans Times Picayune]]'' this is an "[[urban myth]]". Reasons for belief in these theories have been ascribed to the decision by city officials during the [[Great Mississippi Flood of 1927]] to set off 30 tons of dynamite on the levee at [[Caernarvon, Louisiana]] which eased pressure on levees at New Orleans but flooded [[St. Bernard Parish]], the [[Ninth Ward]] taking the brunt of the city's flooding during [[Hurricane Betsy]], the general disenfranchisement of blacks and lower-class people, and the similarity of the sound of the levees collapsing to that of a bombing.<ref>
==See also==
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==Further reading==
{{refbegin}}
Rosenthal, Sandy, ''Words Whispered in Water: Why the Levees Broke in Hurricane Katrina'' (Mango, 2020), non-fiction account of author’s battle to expose Army Corps of Engineers{{refbegin}}▼
*Bush, Ann McReynolds, "Katrina: 10 Years On" (year 2015 publisher+Amazon▼
*Horowitz, Andy. Katrina: A History, 1915–2015 (Harvard University Press, 2020), long-term scholarly perspective.
▲*Rosenthal, Sandy, ''Words Whispered in Water: Why the Levees Broke in Hurricane Katrina'' (Mango, 2020), non-fiction account of author’s battle to expose Army Corps of Engineers
*{{cite book |last=van Heerden |first=Ivor |author2=Bryan, Mike |title=What Went Wrong and Why During Hurricane Katrina |year=2006 |publisher=Viking |isbn=0-670-03781-8 |url-access=registration |url=https://archive.org/details/stormwhatwentwro00vanh }}
{{refend}}
▲Bush, Ann McReynolds, "Katrina: 10 Years On" (year 2015 publisher+Amazon
==External links==
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