How Katrina and Rita Affected the Delta

In the late summer of 2005, Louisiana and its neighbors suffered through two massive hurricanes. These storms brought unprecedented destruction and ultimately demonstrated the catastrophic impact of land loss on the economic and environmental vitality of the central Gulf Coast.

The first of these storms, Hurricane Katrina, made landfall in Plaquemines Parish as a Category 3 hurricane on August 29, 2005. The second, Hurricane Rita, came ashore in southwestern Louisiana on September 24, 2005 and cut through a sliver of Cameron Parish before plowing its way across eastern Texas.

Together, the two storms resulted in nearly two thousand deaths and an estimated economic toll of $91 billion, with $81 billion of the losses coming from Katrina. Louisiana bore much of the burden, with about 1,300 casualties from Katrina and the subsequent levee failures, as well as heavy losses in commercial fishing and other industries. Aside from their devastating impact on the lives of millions of Gulf Coast residents, the storms damaged the Mississippi River Delta and other fragile ecosystems that lay in their path.

Weaker Wetlands, Stronger Storm Surges

Hurricane Katrina in the Gulf of Mexico. Credit: GOES 12 Satellite, NASA, NOAA.

Coastal Louisiana's land loss directly contributed to the storms' human toll. In the past, extensive healthy wetlands buffered South Louisiana from storm surge, but with thinning wetlands, oyster reefs and barrier islands, the area's communities have lost much of their natural protection.

These protections have eroded through the years as a result of many factors, with one of the biggest contributors to this loss being the river levee systems that shunt river-borne sediment and other land-building material out into the Gulf of Mexico. Severing the connection between the river and its delta has dealt a crippling blow to many of the marshes, swamps and natural breakwaters lining the Louisiana coast. In the decades between the commencement of massive levee projects in coastal Louisiana and the landfall of Hurricane Katrina, nearly 2,000 square miles of deltaic wetlands — a necessary but often overlooked part of the region’s flood defenses — disappeared beneath the water, lost because the disconnected river no longer delivers replenishing land-building material to a sediment starved delta. (Read more about what went wrong.)

Moreover, the remaining marshes and swamps are not as robust as they once were. The extensive wetlands that once lay to the south and east of New Orleans and protected it from storms have been threaded with oil pipeline ditches and navigation canals like the Mississippi River Gulf Outlet (MRGO). These man-made intrusions bring salt water deep into the brackish and freshwater wetlands of southern Louisiana, disrupting the salinity balance required by the plants that hold wetland soils together. This intrusion of ocean water results in areas that appear healthy on the surface but are too weak to withstand storms of Katrina's or Rita’s strength.

Why Action Is Needed Now

The disappearance and destruction of millions of acres of wetlands have left Louisianans with fewer natural defenses to protect them from future hurricanes. Without urgent action to rebuild the region’s wetlands and reverse the damage wrought by Katrina and Rita, major sections of the Mississippi River Delta could vanish the next time a successor to these storms strikes the Gulf Coast.

Resources:

  • MRGO Must Go – restoring the wetlands and protecting the people affected by the Mississippi River-Gulf Outlet