Hurricanes: Katrina Environmental Impacts

Introduction

Hurricane Katrina formed on August 25, 2005. It passed over southern Florida and into the Gulf of Mexico, where it strengthened into a category 3 hurricane. When it again made landfall along the northeastern Gulf coast of the United States, it had become a category 5 hurricane, and was the third-strongest hurricane ever to affect the United States.

The coast of Mississippi was devastated by the winds and accompanying storm surge that, in places, traveled up to 6 mi (9 km) inland and over 10 mi (16 km) upstream in streams and rivers. As well, portions of the coast of Alabama, which were up to 100 mi (160 km) away from the storm’s center, were greatly damaged.

Over 1,800 people died directly due to the hurricane and the subsequent floods. The environmental damage created by the storm was enormous. One estimate of the amount of debris—100 million cubic yards—would be enough to cover more than 1,000 football fields with waste to a depth of 50 ft (15 m). By comparison, the debris from the collapsed World Trade Center towers was approximately 1.5 million tons.

In New Orleans, Louisiana, more than 50 breaks in levees and floodwalls resulted in the flooding of 80% of the city. Neighborhoods were destroyed and residents evacuated. In 2008, most of these neighborhoods remain essentially unrepaired and the residents have yet to return to the city or move from the mobile trailers that were supplied by the U.S. Federal Emergency Management Agency (FEMA). Late in 2007, it was discovered that many of the trailers have problems with the growth of mold and outgassing of formaldehyde.

The human tragedy and economic devastation caused by the hurricane was accompanied by extensive environmental damage. Although some of the environmental damage, such as the flooding, was relatively short-lived, other damage remains. For example, in homes that were flooded and left abandoned, the presence of mold and mold toxins remain as a legacy of the storm. As residents continue to return to New Orleans, home renovations carry the risk of illness due to the inhalation of the microbial growth and toxins.

Historical Background and Scientific Foundations

The direct environmental damage due to Hurricane Katrina was extensive. For example, in Mississippi, as the hurricane bore down on the coastline from the Gulf of Mexico, the sustained winds that were as high as 120 mph (193 km/h) pushed waves along. As the land became shallower nearer to the shore, the wave height built considerably. The resulting storm surge produced waves that were almost three stories high. The waves, combined with the 8 to 10 in (20 to 25 cm) of rain that fell along the coast and over 4 in (10 cm) through the remainder of the state, produced extensive flooding of land and the interior of buildings. In one documented example, waves that struck a Gulfport, Mississippi, hotel that was 250 ft (76 m) from the shoreline left a waterline that was about 10 ft (3 m) above the ground. Calculations determined that the surging waves must have been 28 ft (8.5 m) high when they came ashore

The flooding caused many spills of noxious chemicals. Data from the U.S. Coast Guard and the Environmental Protection Agency (EPA) documents 575 reports of petroleum or hazardous chemicals spills. In the frenzy of the hurricane, most could not be cleaned, and the chemicals were more widely distributed by the floodwaters. Seven of these spills alone released 7 million gallons of oil, meaning that the actual total amount was far higher.

An estimated 350,000 vehicles were trapped in the floodwaters. The gasoline in their tanks could have been

WORDS TO KNOW

FEMA: The United States Federal Emergency Management Agency, founded in 1979 as an agency of the Department of Homeland Security, is responsible for coordinating responses to disasters taking place within the United States.

LEVEE: A raised embankment designed to prevent a river from overflowing.

STORM SURGE: Rise of the sea at a coastline due to the effect of storm winds.

SUPERFUND SITE: A Superfund site is a location contaminated by hazardous waste that has been designated by the United States Environmental Protection Agency (EPA) for management and cleanup.

released as well. Using a conservative estimate of 8 gallons of gas per vehicle, the floodwaters could have contained an additional 3 million gallons of gas. As a comparison, the Exxon Valdez oil spill that occurred off the coast of Alaska, and which was viewed as an environmental catastrophe, involved 11 million gallons of oil.

At least four Superfund sites (sites identified by the EPA as being highly contaminated and which receive funds for clean-up) in the New Orleans region were hit by the storm.

The storm surge associated with Hurricane Katrina also stirred up the sediment in rivers. A legacy of decades of lax environmental disposal practices in some areas of Louisiana has been the settling of toxic compounds in the sediment of riverbeds. The storm surge stirred up the toxic sediment and re-deposited it on industrial, agricultural, and residential land during the flooding. The environmental consequences of this are not clear as of 2008, and remediation attempts would have to be done on a huge scale involving the excavation of hundreds of square miles of land.

In addition to distribution in floodwaters, noxious chemicals were also spread by the high winds. EPA air monitoring data recorded higher than acceptable levels of chemicals, including benzenes and xylene, in the air that was near some spills sites. Although this air pollution would have probably been an environmental hazard for only a short time, even with the burning of debris that occurred in the months following the disaster, more disturbing data have continued to be collected from some of the hardest-hit neighborhoods in New Orleans. Periodically since the 2005 disaster, the EPA has monitored the air levels of gases including benzene in the still-abandoned neighborhoods of the city using a bus equipped with sensitive air monitoring equipment. Data published on the EPA Web site have documented benzene levels that are deemed unsafe by the National Institute of Environmental Health Sciences.

Impacts and Issues

Hurricane Katrina devastated the natural environment of coastal regions of Mississippi, Alabama, and Louisiana. The sustained winds that topped 120 mph (193 km/h), driving rain, and storm surge caused erosion and flood-related damage. In addition, the release of toxic compounds from industries and vehicles, and the redistribution of poisons already present in the sediment, will continue to produce consequences. The severity of the environmental damage is difficult to assess, since much is likely yet to appear.

At the same time, as debris has been cleared away and, in particular, New Orleans has restored the downtown core and facilities like the Superdome have reopened, the public perception has become that the worst has passed. Yet, there is a great deal of environmental remediation to be accomplished, especially in the New

Orleans area. According to legislation that includes the Clean Water Act, Resource Conservation and Recovery Act, Comprehensive Environmental Response, Compensation, and Liability Act (the Superfund legislation), and the Oil Pollution Act, the EPA bears the

IN CONTEXT: HURRICANE KATRINA

Hurricane Katrina, which made landfall three times during August 2005, brought waves of destruction to areas from Pensacola, Florida, to the northern coast of Texas. Katrina caused more that $80 billion in damage to insured properties and killed more than 1,800 people, making it the most expensive natural disaster in U.S. history. Estimates of the total economic damage, which include uninsured property, range as high as $125 billion.

The most deadly natural disaster in U.S. history was the Galveston hurricane of 1900, which killed an estimated 6,000 to 12,000 people.

Katrina initially crossed Florida as a Category 1 hurricane and weakened to a tropical storm over land. It regained strength as it crossed back over the warm waters of the Gulf of Mexico, increasing to a Category 5 hurricane. The storm decreased to a Category 3 hurricane as it made landfall east of New Orleans in Plaquemines Parish, Louisiana; crossed open water along the coast; and made landfall for the third time as a Category 3 hurricane near the Louisiana-Mississippi border.

The approach of Katrina as a category 5 hurricane prompted a mandatory evacuation of New Orleans, a city in which many areas are below sea level. Despite warnings, many residents remained in New Orleans either by choice or necessity (for example, some residents did not have transportation or were hospitalized). Most of the city was flooded when heavy rains and the storm surge, which was measured at 12 ft (3.6 m) to 14 ft (4.3 m) in different locations, caused levees between New Orleans and Lake Ponchartrain to fail after the storm had passed. Damage from rain and wind were minor compared to that caused by flooding after the storm.

In addition to levee breaks, flooding occurred when levees were topped and supporting soil was eroded by fast-moving water. Some levees were also not as high as had been intended, a situation that may have been exacerbated by regional land subsidence (a gradual lowering of Earth’s surface). As of 2008, reconstruction efforts continue and the full impact of the tremendous amount of oil, sewage, pesticides, and toxic industrial waste spillage on the soil, groundwater, and larger ecosystem have yet to be fully assessed.

responsibility for remediating the environmental damage caused by Hurricane Katrina. Yet, as of 2008, the agency and FEMA have not assumed much of this responsibility, instead passing the task on to local agencies. The local agencies do not have the staff, equipment, or budget

needed to accomplish the tasks, while at the same time being pressured to permit the resettlement of neighborhoods that have been abandoned since 2005.

A scientific study published in 2007 that chronicled mold and mold-associated toxin levels in still-abandoned houses in New Orleans showed that many of these buildings contain unhealthy levels of mold and toxins. A report released by the EPA in conjunction with the Centers for Disease Control and Prevention (CDC) indicates that 80% of these buildings are at risk. Unless these buildings are professionally cleaned prior to rehabitation, respiratory illnesses, skin irritation, and even more severe maladies are likely, especially for those with asthma, allergies, or a malfunctioning immune system.

The effect of Hurricane Katrina may have been worsened by the loss of coastal marshlands that has occurred in Louisiana since the 1930s. Much of this loss—almost 2,000 square mi (5,180 square km)—has been due to the construction of levees and canals. The effect has been to move New Orleans closer to the unprotected waters of the Gulf of Mexico. If present, marshland would help absorb and lessen incoming storm surges, and would help lessen the strength of the storm as it moved inland. Studies have shown that storm surges rise by one foot for every square mile of wetland that is lost.

See Also Ecodisasters; Floods; Weather Extremes

BIBLIOGRAPHY

Books

Brinkley, Douglas. The Great Deluge: Hurricane Katrina, New Orleans, and the Mississippi Gulf Coast. New York: Harper Perennial, 2007.

Robinson, Darren. Hurricane Katrina: The Destruction of New Orleans. Charleston: Booksurge Publishing, 2005.

Periodicals

Chew, G. L., J. Wilson, F. A. Rabito, et al. “Mold and Endotoxin Levels in the Aftermath of Hurricane Katrina: A Pilot Project of Homes in New Orleans Undergoing Renovation.” Environmental Health Perspectives 114 (2006): 1883–1889.

Brian D. Hoyle