The Environmental Protection Agency defines wetlands as "an area that is regularly saturated by surface water or groundwater and is characterized by a prevalence of vegetation that is adapted for life in saturated soil conditions (e.g. swamps, bogs, fens, marshes, and estuaries). Although these areas make up a very small percentage of the total land found in the United States, Southern Louisiana contains 40 - 45% of the wetlands found in the lower 48 states. This is because Louisiana is the drainage gateway to the Gulf of Mexico for the Lower Mississippi Regional Watershed. The Lower Mississippi Regional Watershed drains more than 24 million acres (97,000 km²) in seven states from southern Illinois to the Gulf of Mexico. The eastern coastline of Louisiana is much more susceptible to erosion than the western coastline because much of the eastern coastline was created by silt deposits from the Mississippi River. The western coastline is marshy, but the marshes only extend inland by at the most, then the elevation begins to increase and the marshes fade into solid grounded praries. Therefore, rising sea levels due to global warming, and coastal erosion, are not and will not affect the western coastline as profoundly as it will the eastern half, which may cease to exist.
Throughout the 1900s, as billions of barrels of oil and saltwater and as trillions of cubic feet of gas were removed from the subterranean structures in which they had accumulated over millions of years, these structures lost their ability to support the weight of the earth above. As these structures slowly collapsed, everything above gradually subsided. The wetlands on the surface began to sink into the gulf waters.
Beginning in 1930, an extensive levee system aided by locks and dams was developed in the waterways of the lower Mississippi Regional Watershed. The levees, designed to prevent flooding along the waterways, direct drainage water directly into the Gulf of Mexico and also the river's silt is directed from its mouth directly into the Gulf of Mexico. So with no new accretion and with loss of structure below, the wetlands subside and are lost. The levee system prevented the water draining downward towards the Gulf from entering the wetland areas of southern Louisiana. As a result of this engineering, a great deal of the marshes and swamps found in southern Louisiana are being consumed by the Gulf of Mexico due to extraction and production of oil and gas. Since 1930 water has consumed more than 1,900 square miles (4,900 km²) of the state’s land. This loss equates to the disappearance of 25 square miles (65 km²) of wetlands each year or a football field sized area every 30 minutes.
Southern Louisiana’s disappearing wetlands have a broad impact ranging from cultural to economic. Commercial fishing in Louisiana accounts for more than 300 million dollars of the state's economy. More than 70% of that amount stems from species such as shrimp, oysters and blue crabs that count on the coastal wetlands as a nursery for their young. Annually Louisiana sells more than 330,000 hunting licenses and 900,000 fishing licenses to men and women who depend on the wetlands as a habitat for their game. Additional recreational activities such as boating, swimming, camping, hiking, birding, photography and painting are abundant in wetland areas. Wetlands host a variety of trees such as the Bald Cypress, Tupelo Gum and Cottonwood. Scrub plants such as the Saw Palmetto and Wax Myrtle and aquatic plants such as Water Hyacinths and Duckweeds need wetland areas to thrive. (Water Hyacinths are an invasive plant species that out-compete native emergent vegetation.) Some plants help remove heavy metals, sewage and pesticides from the polluted water. Animal species native to these areas such as Ospreys, Herons, Egrets, Alligators and Beavers are losing large areas of natural habitat and valuable food resources. Although there are several naturally occurring forces that adversely affect the wetland regions of Louisiana, many believe it is human intervention that has caused the majority of the decline.
Prior to the building of levees on the Mississippi River, the wetlands were maintained by occasional floods, which fill the area with sediment, and subsidence, which eroded away the wetlands. After the levees were built, flood sediment went directly into the Gulf of Mexico. The unabated subsidence along with the recent sea level rise eroded away the wetlands faster than usual, causing a relative sea level rise of 3 feet (0.9 m). This, along with the canals built in the area, caused decline of the wetlands and also caused less weakening of recent hurricanes such as Hurricane Katrina.
HURRICANE ON THE BAYOU: ; Film takes close look at wetlands of Louisiana; Story of the state's swamps is told through eyes of four musicians
Mar 05, 2009; If you go What: "Hurricane on the Bayou" When: Premieres Saturday Where: Clay Center Info: www.theclaycenter.org or 304-561-3570...