How many people died in Hurricane Katrina? The death toll is reduced 17 years later.

The mystery of how many people died as a result of Hurricane Katrina and the federal levee failures that accompanied it is still being puzzled over more than 17 years after the storm’s devastation. A new toll taking into account findings from medical logs has reduced the number significantly -- by around one quarter.

The revised Katrina toll was one of several disaster-related findings unveiled by federal officials in recent days. Others include Louisiana being classified as the state most affected by climate-related disasters since 1980 when considered proportionately. New damage estimates also keep Katrina as the costliest storm ever despite 18 natural disasters in 2022 with billion-dollar price tags.

Those include Hurricane Ian, which made landfall in Florida and caused $119 billion in estimated damages, the third costliest on record. Katrina’s inflation-adjusted damages total $190 billion, according to NOAA’s National Centers for Environmental Information.

And while the National Hurricane Center has now adjusted Katrina’s death toll downward to 1,392, from an earlier estimated 1,833 deaths, it still accounts for the second-highest U.S. death toll for weather disasters in modern times. It follows 2017’s Hurricane Maria, which killed 2,981 in Puerto Rico and the U.S. Virgin Islands.

Katrina also retains its rank as the third-highest death toll from a hurricane in recorded U.S. history, behind the estimated 8,000 dead in the 1900 Galveston hurricane, and the more than 2,500 dead in the 1928 Lake Okeechobee, Fla., storm.

The upward adjustment of Katrina’s damage estimate was expected with the dramatic hike in inflation in 2022, though Ian’s tally is likely to grow over the next few years as more accurate damage estimates are completed. Katrina’s damage in 2005 dollars was estimated at $125 billion.

Hurricane Harvey, the 2017 storm that delivered more than 60 inches of rain to the Houston area, remains in second place among weather disasters with a 2022 inflation-adjusted damage total of more than $151 million.

Drowning and indirect causes

The downward adjustments of Katrina’s death toll actually date back to two scholarly papers published in 2014 and 2016 by the American Meteorological Society that reviewed the way deaths were counted for recent hurricanes.

In the National Hurricane Center’s 2023 Katrina report update, its authors say the changes recommended by the two papers resulted from reviews of medical logs of more than 1,000 victims provided by state officials in Louisiana and Mississippi.

The new counts found that 520 of the deaths, including 341 in Louisiana, were directly caused by Katrina, mostly the result of drowning. Another 565 deaths were considered indirectly caused by the hurricane, and according to the Louisiana State Office of Epidemiology, more than half of that category in the state resulted from “cardiovascular failure,” mostly heart attacks.

Other indirect causes include evacuation accidents not caused by vehicles; vehicle accidents, including those with trees involved; accidents directly involving only trees; and several related to electricity, including carbon monoxide poisoning involving the use of emergency generators, and electrocution. Falls were the final indirect death category.

According to the report, officials could not determine the direct or indirect cause of death for another 307 victims. Most of the total deaths occurred in Louisiana, but an exact breakdown for those due to indirect causes was not provided.

In the aftermath of Katrina, victims were found days and weeks after the storm, many only after water levels in the New Orleans area subsided. Some victims were caught by water in their homes, or died caught in attics during the 90-degree days that followed.

Federal and state officials operated an interim mortuary for several months in St. Gabriel to determine death causes and to identify the bodies. Many bodies were recovered by the National Guard or other agencies conducting building-by-building searches after the storm, even as water was still being pumped out of the area.

“Presumably, most of the deaths in Louisiana were caused by the widespread storm surge-induced flooding and its miserable aftermath in the New Orleans area,” the hurricane center report said. “Louisiana also reports that persons of more than 60 years of age constituted the majority of the Katrina-related fatalities among its residents.”

In the aftermath of Katrina, a forensic investigation of the causes of flooding in the New Orleans area sponsored by the Department of Defense concluded that numerous floodwalls along major drainage canals were improperly designed or built, leading to their collapse or being pushed inward as much as 35 feet into neighborhoods, allowing surge from Lake Pontchartrain to flow in unabated.

Much of the earthen levees in the system had sunk as much as 2 feet below their authorized heights in the years before Katrina. The overtopping of those levees by the hurricane’s surge caused many stretches to erode to near sea level because improper materials were used in their interiors during construction.

That, in turn, caused them to simply wash away. Surge and post-storm high water entered those breaches for several days after the storm moved out of the area.

Climate-related disasters

The new data, released by NOAA and NASA last week, also focused on connections between human-caused global warming and past and future weather disasters.

Louisiana has experienced between $200 billion and $290 billion in weather-related damages between 1980 and 2022, according to the National Centers for Environmental Information, with tropical weather events being the most costly, representing between $200 billion and $250 billion of that damage.

Other flooding events represent as much as $50 billion of the total, while other severe storms caused up to $20 billion, drought conditions caused up to $10 billion, and winter storms represented up to $5 billion.

Louisiana ranks at the top of the damages scale nationally for climate-related disasters, when the damages are averaged per million residents over that same time period.

Louisiana had between $50 billion and $100 billion in damages per million residents. In second place were Florida, Mississippi and South and North Dakota, each with $20 billion to $50 billion per million residents.

Louisiana’s damage totals also represented between 2% and 3% of the state’s gross domestic product during those years, again ranking the state at the top of the national damage list.

The same four states were in second in that category, with damages equal to 1% to 2% of their gross domestic product.

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THIS WORK IS SUPPORTED WITH A GRANT FUNDED BY THE WALTON FAMILY FOUNDATION AND ADMINISTERED BY THE SOCIETY OF ENVIRONMENTAL JOURNALISTS.