The Mississippi River runs from Minnesota to the Gulf of Mexico. Much of southern Louisiana was created as the river overflowed its banks and deposited sediment into the wetlands. This replenished the swamp land, preventing natural sinking, and allowed plant life to flourish. However, flooding caused damages to property and crops, so levees were built along the river to prevent flooding. While this worked, the levees prevented soil from being deposited, leading to increased sinking and the inability of the wetlands to replenish themselves.
New Orleans' proximity to the Gulf of Mexico and the Mississippi River positions it as one of the key ports in the country, especially for rubber, coffee, grain, sugar and steel. The Mississippi River Gulf Outlet, known as the Mr. Go, was created in the 1960s by the Army Corps of Engineers to reduce the time required to travel from the Gulf of Mexico into the Port of New Orleans via the Industrial Canal. Unfortunately, the construction eliminated even more wetlands -- 23,000 acres originally. The Mr. Go also increased saltwater intrusion into freshwater, which kills plants that hold the soil together. The Mr. Go was a key factor in increasing the extent of the damage caused by Hurricane Katrina in 2005.
There are several offshore wells for natural gas and oil production off the coast of Louisiana. The pipelines required to ship gas and oil to shore, and canals cut for traffic, as well as ongoing small spills, have all contributed to destruction of wetlands. However, the explosion on April 20th, 2010, of the Deepwater Horizon rig led to three months of oil spilling into the Gulf of Mexico. Throughout the coastal areas -- including Florida, Alabama, Mississippi, Louisiana and Texas -- oil came ashore. The hardest hit area was in Louisiana. Oil in the marshes and the resulting clean-up sped destruction of the wetlands significantly.
The loss of coastal wetlands increased the damage caused by Hurricanes Katrina and Rita in the fall of 2005. Wetlands are often called "nature's natural speed bump," because three miles of wetlands will reduce storm surge caused by hurricanes by one foot. The hurricanes also increased the loss of wetlands; approximately 200 square miles were lost compared to the annual average of 34 square miles. Bayou Sauvage, the largest urban wetland in the United States, was severely damaged by Hurricane Katrina and was transformed from a swamp with a full tree canopy to a large area of water with stumps.
Land loss doesn't need to be permanent, but reversing it will take a great deal of time and money. Loss can be slowed through shoreline protection and restoring barrier islands. Wetlands can be restored by planting new marsh grasses and putting dredged sediment back into the wetlands.
