Monday, August 28, 2006

One Year Later: Katrina and the Environment

On August 29, 2005, Katrina struck New Orleans and the U.S. Gulf Coast. The result was an unbelievable - though foreseeable - disaster for the humans living there, with a death toll over 1700 and tens of thousands of refugees. The images of protracted human suffering were unforgettable. The storm was also a disaster for the environment. How bad was it, and what is the likely road ahead? This post looks at some of the problems.

The destruction caused by Hurricane Katrina came in two forms: the wind and tidal action of the hurricane itself, and the flooding of New Orleans and its suburbs when levees failed along the city's canals. When Katrina hit the Gulf Coast, it was a Category 3 hurricane; it had been as high as Category 5 as it moved through the Gulf of Mexico. The hurricane was also massive, which meant that these intense winds were spread over a wide area.


Initial news reports described the waters that engulfed New Orleans as a "toxic gumbo" because of the mix of toxic waste released into the waters in the wake of the hurricane. Since petroleum is one of the main industries of the Gulf Coast, it should be no surprise that petroleum spills were a major contributor. At least 44 spills have been recorded. The largest spill released 3.78 million gallons, and another released 1.05 million gallons. The rest were smaller but significant enough for the total to surpass 7 million gallons.

Besides petroleum, other toxic chemicals were released into the waters and sediments in and around New Orleans. Chemicals in the waters included lead, arsenic, chromium, benzene, toluene, ethylbenzene. (For more on these hazards, see ToxTown.) Reuters reported at the time that over 500 sewage facilities were disrupted by the storm, so that raw sewage was spilled into the mix as well. People who returned to their homes after the storm found them infested with toxic mold. The waters laden with chemicals were pumped into Lake Pontchartrain after the storm.

The waters may have been less toxic than originally feared. The levels of most harmful chemicals and bacteria, while high, turned out to be on par with those in normal stormwater runoff. Tests conducted by the EPA indicate that the sediments left in their wake are generally not harmful. Even so it suggests caution in handling them.

Local and federal officials have insisted that New Orleans is safe, but there remains widespread skepticism in the public. Partly this is because independent organizations, such as the Natural Resources Defense Council, have come to different conclusions than government agencies about the human health risks present in New Orleans's battered neighborhoods. Other groups found high levels of heavy metals in the neighborhoods around the Murphy's Oil spill. In addition, while the levels of toxins may not be harmful to humans, they are harmful to fish in Liake Pontchartrain.

Wetland and Habitat Destruction

The same forces that wrecked New Orleans damaged or destroyed wetlands along the Gulf Coast. Barrier islands took the brunt of the damage. For example, large chunks of the Chandeleur Islands were obliterated. Wetlands suffered less from wind damage than from flood waters that dumped salt water, trash, and toxic chemicals into the fragile ecosystems. When salt water is introduced into a fresh water refuge it kills the vegetation. Sabine NWR took a heavy hit from Hurricane Rita, which dumped hundreds of thousands of gallons of toxic waste into the refuge. Bayou Sauvage NWR (pictured at right) received tons of trash.

The destruction of wetlands and coastal habitat occurred in a sensitive area for birds. The northern Gulf Coast is a stopping point for birds crossing the Gulf of Mexico in migration; it also serves as nesting ground for many species of terns and other waterbirds. Damage to the barrier islands was particularly bad for the nesting species; nests this year are way down for several species. Threatened birds in the area include a rare Sandhill Crane subspecies. Twelve Important Bird Areas lay in Katrina's path: 2 in Florida and 10 on the northern Gulf Coast. The hardest hit were Breton NWR and the Gulf Islands National Seashore. Dauphin Island, a spring migrant trap, moved northward after the repeated blows of Ivan and Katrina. Other significant areas were also heavily damaged. A full accounting of the effects of the storm on birds will probably not be known until results from this year and next year's Breeding Bird Surveys and Christmas Bird Counts are tabulated.


Solutions to the problem of land loss are difficult. Coastal Louisiana faces two causes of land loss: erosion and subsidence. Erosion causes the state to lose about 25-30 square miles of land per year, enough for over 1,500 square miles to have been lost since 1930. Katrina and Rita subtracted an extra 100 square miles in successive blows. ( has highly detailed images of erosion damage in the affected areas. Do not use that site unless you have a fast connection and a fast computer.) Subsidence is a natural process aggravated by the flood control projects of the early twentieth century. The system of levees and floodgates forces the Mississippi River to bypass the delta and dump its sediments into the Gulf of Mexico. Without levees, these waters would spread across the delta and distribute their sediments to build up the land. The image below (via Restore or Retreat) shows the effects of these two factors over the past 150 years.

Coastal erosion and subsidence are not simply aesthetic problems, and wetland damage does not only harm wildlife. Coastal wetlands serve as buffer zones that absorb much of the energy and flooding associated with hurricanes and other large storms. They protect inland cities like New Orleans from the worst effects. Removal of this buffer allows high winds and flooding to penetrate farther inland towards population centers. Thus any rebuilding project for New Orleans must involve some answer to the land loss problem.

Restoration of the wetlands will require substantial investment from the government. The cost may total $14 billion over 20 years. While some funding has been directed to restore existing refuges, the sum does not approach what it would take to do a thorough rebuilding of the coastal marshes. In addition to being expensive, it is also an extraordinarily complex process requiring trial and error because of the many variables at work in any given wetland.

The situation in Louisiana is a good illustration of a point that often is lost in reporting about environmental issues. Such reporting, especially about endangered species, pits human interests against conservation. However, humans are part of the environment, and are just as affected by natural forces as wildlife. In this case, restoration of wetlands and cleanup of toxic wastes will serve both interests. What is good for the animals is necessary for the people, too.

For more links to news articles about Hurricane Katrina from last fall, see the roundup at Birderblog. For more blog commentary about the storm, see the links at Shakespeare's Sister.