Hurricane Katrina

• 1. Introduction

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  Hurricane Katrina formed from a modest tropical disturbance over the southeastern Bahamas on the 23rd of August 2005, and within six days it had become one of the deadliest and most destructive storms ever to strike the United States. By the time Katrina finally dissipated off the coast of Greenland on September 7, it had killed an estimated 1,392 people, flooded 80% of New Orleans, and caused damage estimated at $125 billion. It is tied with Hurricane Harvey as the costliest tropical cyclone in the Atlantic basin. What turned a powerful hurricane into a catastrophe of historic scale was not simply the wind or the rain. It was what happened after: a federally built flood protection system that failed, a government response that collapsed under its own weight, and the displacement of over one million people from the central Gulf Coast. The name Katrina was retired by the World Meteorological Organization in April 2006, a formal acknowledgment that this storm had earned a permanent place in American memory. The questions the storm left behind were harder to close out than the official record.

• 2. The Storm Itself

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  On the 28th of August 2005, at 1800 UTC, Katrina reached its peak strength with maximum sustained winds of 175 mph and a minimum central pressure of 902 mbar. That pressure reading made it the fifth most intense Atlantic hurricane on record at that moment. It had intensified from a Category 3 to a Category 5 in just nine hours, driven by the unusually warm waters of the Loop Current in the Gulf of Mexico. An eyewall replacement cycle had briefly interrupted that intensification but also caused the storm to nearly double in size. By the time Katrina made its second landfall at 1110 UTC on August 29 near Buras-Triumph, Louisiana, it had weakened to a high-end Category 3 with sustained winds of 125 mph and a central pressure of 920 mbar. At that moment, hurricane-force winds extended 120 miles outward from the center. The storm then crossed southeastern Louisiana, made a third and final landfall near the Louisiana-Mississippi border, and pushed well into the interior, maintaining hurricane strength for more than 150 miles inland before finally weakening to tropical storm strength near Meridian, Mississippi. Its remnants were absorbed by a cold front in the eastern Great Lakes region on August 31. The scale of Katrina's reach was enormous: every one of Mississippi's 82 counties was declared a disaster area.

• 3. New Orleans and the Levees

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  On August 29, Katrina's storm surge caused 53 breaches in the flood protection structures surrounding greater New Orleans, submerging roughly 80% of the city. The system that failed was called the Lake Pontchartrain and Vicinity Hurricane Protection Project, authorized by Congress in the Flood Control Act of 1965. The U.S. Army Corps of Engineers had been tasked with its design and construction. The project was initially estimated to take 13 years, but when Katrina arrived in 2005, parts of it were only 60-90% complete, with a revised completion date of 2015. A June 2007 report by the American Society of Civil Engineers determined that the levee failures were primarily the result of system design and construction flaws. A key cause was a decision to use shorter steel sheet pilings to save money. A 2015 report in the official journal of the World Water Council traced this to a misreading of a 1985 study: the Corps concluded that sheet piles needed to be driven to only 17 feet, when the correct depth was between 31 and 46 feet. That cost-cutting decision saved approximately $100 million but reduced the system's reliability catastrophically. Major breaches occurred at the 17th Street Canal levee, the London Avenue Canal, and the wide Industrial Canal. The Mississippi River Gulf Outlet breached in approximately 20 places, flooding much of eastern New Orleans and most of St. Bernard Parish. A later federal appeals court ruled that the Army Corps, despite being responsible for the failures, could not be held financially liable under the Flood Control Act of 1928.

• 4. The Failure to Evacuate

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  At a news conference at 10 a.m. Eastern time on August 28, New Orleans mayor Ray Nagin ordered the first-ever mandatory evacuation of the city, calling Katrina "a storm that most of us have long feared." By that point, some forecasts gave the storm a 29% chance of a direct hit on New Orleans, and the predicted storm surge of 28 feet exceeded the levees' protection capacity of 23 feet. The problem was timing and logistics. Louisiana's hurricane evacuation plan called for New Orleans to begin evacuating 30 hours before tropical-storm-force winds arrived. Critics later charged that Nagin's order came 19 hours before landfall, which led to deaths among those who could not find a way out. Governor Blanco did not sign an emergency waiver that would have allowed any licensed driver to operate school buses for evacuations, and many private caregiving facilities waited too long to act. About 100,000 to 150,000 people remained in the city despite mandatory evacuation orders. The Louisiana Superdome was designated a refuge of last resort and sheltered approximately 26,000 people. National Guard personnel who could have driven available buses were not deployed in time, while buses that later flooded sat unused. The National Hurricane Center's Max Mayfield expressed concern directly to the president during video conferences on August 28 and 29, stating that he could not say with confidence whether the levees would be topped.

• 5. Government Response and Criticism

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  Federal Emergency Management Agency director Michael D. Brown was designated as the Principal Federal Official to coordinate the federal response. Eight days after landfall, he was recalled to Washington; three days later he resigned. New Orleans Police Department superintendent Eddie Compass also resigned. The neologism "Katrinagate" was coined to describe the controversy over the government's response and was a runner-up for the 2005 word of the year. At the Superdome, only six deaths were confirmed among the thousands sheltered there, though reports of widespread violence circulated widely. Some news agencies later printed retractions, acknowledging that many reports had been inaccurate, greatly exaggerated, or completely false. Of the roughly 60,000 people stranded in New Orleans, the Coast Guard rescued more than 33,500, operating round-the-clock, with many crew members having lost their own homes in the storm. Congress later recognized the Coast Guard's effort with an entry in the Congressional Record and awarded the service the Presidential Unit Citation. A congressional investigation found that FEMA and the Red Cross "did not have a logistics capacity sophisticated enough to fully support the massive number of Gulf coast victims." An ABC News poll conducted on the 2nd of September 2005, found that 75% of respondents blamed state and local governments while 67% blamed the federal government, with 44% blaming President Bush's leadership directly.

• 6. The Human Toll

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  Louisiana bore the heaviest loss of life. According to the National Hurricane Center's figures, 1,577 people died in Louisiana, 238 in Mississippi, 14 in Florida, and smaller numbers in Georgia, Alabama, Ohio, and Kentucky. A follow-up study by the Louisiana Department of Health and Hospitals put the storm's direct responsibility in Louisiana at 1,170 fatalities. An estimated 215 bodies were found in nursing homes and hospitals in New Orleans, with the largest single recovery at Memorial Medical Center, where 45 corpses were recovered. Three nursing home patients died during an evacuation to Baton Rouge on the night of August 28, most likely from dehydration, in what were reported as the first deaths from the city. At Danziger Bridge, police officers killed two unarmed civilians and seriously injured four others. Five former officers later pleaded guilty to charges connected to those shootings. Federal disaster declarations covered 90,000 square miles of the United States, an area nearly as large as the United Kingdom. The hurricane left three million people without electricity. Homeland Security Secretary Michael Chertoff described the aftermath on the 3rd of September 2005, as "probably the worst catastrophe or set of catastrophes" in the country's history. American flags were ordered to fly at half-staff from September 2 through the 20th of September 2005, in honor of the victims.

• 7. Displacement and Economic Damage

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  Katrina displaced over one million people from the central Gulf Coast, creating what became the largest diaspora in the history of the United States. Houston, Texas, absorbed an increase of 35,000 people; Mobile, Alabama, gained over 24,000; Baton Rouge received over 15,000; and Hammond, Louisiana, received over 10,000 new residents, nearly doubling its size. By late January 2006, only about 200,000 people had returned to live in New Orleans, less than half the pre-storm population. By July 2006, the U.S. Census Bureau recorded a population decline in Louisiana of 219,563, or 4.87%. The Bush administration sought $105 billion for repairs and reconstruction, and Congress authorized $62.3 billion in aid early in September 2005. The total economic impact in Louisiana and Mississippi was estimated to eventually exceed $150 billion. Katrina damaged or destroyed 30 oil platforms and caused the closure of nine refineries. In the six months following the storm, shut-in oil production from the Gulf of Mexico amounted to approximately 24% of annual production, and shut-in gas production was about 18%. In Mississippi alone, 1.3 million acres of forest lands were destroyed, with total forestry losses calculated to reach about $5 billion. Some insurance companies stopped insuring homeowners in the region or raised premiums substantially after Hurricanes Katrina and Rita. Before the storm, the region supported approximately one million non-farm jobs, 600,000 of them in New Orleans.

• 8. Environmental Aftermath

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  The storm caused oil spills from 44 facilities throughout southeastern Louisiana, releasing over seven million gallons of oil. A spill at the Murphy Oil refinery oiled approximately 1,800 homes in Chalmette and Meraux. The floodwaters that covered New Orleans were pumped into Lake Pontchartrain over 43 days; those waters contained raw sewage, bacteria, heavy metals, pesticides, toxic chemicals, and oil. Thomas La Point, director of the Institute of Applied Sciences at the University of North Texas, described the situation as a "toxic soup." The U.S. Geological Survey estimated that 217 square miles of land were transformed to water by Hurricanes Katrina and Rita combined. About 20% of the local marshes were permanently overrun by water. Breton National Wildlife Refuge lost half its area in the storm, and 16 National Wildlife Refuges were forced to close. The habitats of sea turtles, Mississippi sandhill cranes, red-cockaded woodpeckers, and Alabama Beach mice were all affected. Tree mortality rates in the Gulf Coast region rose from a standard pre-storm rate of 1.9% to 20.5% by the end of 2006. By 2006, the loss of biomass in bottomland hardwood forests was contributing an amount of carbon equivalent to roughly 140% of the net annual U.S. carbon sink in forest trees. Delayed tree mortality continued at rates of up to 5% through 2011, a years-long ripple from a single storm.