This hypoxic zone cannot support normal marine life and is caused by human activities throughout the Mississippi River's drainage basin, which encompasses forty percent of the continental United States. The continuing loss of Louisiana's vegetated coastal wetlands certainly rises to the level of crisis. This loss places at increasing risk the unique cultural heritage of coastal residents, whose lifestyle is closely attuned to the environment. Also at risk are billions of dollars in infrastructure, homes, schools, roads, towns, cities, ports, businesses, industries, and support and storage facilities. Moreover, coastal marshes are essential to various lifestages of over ninety percent of commercially and recreationally important marine species.
Marsh loss threatens the very productive Gulf fisheries and the livelihoods of many.
While coastal wetland loss in Louisiana is caused in part by subsidence, a natural process in the Louisiana delta, it has been greatly accelerated by human activity. Following the disastrous 1927 flood, levees were built along the Mississippi River, stretching from upland areas all the way to the Gulf. These levees cut off the river from its natural floodplain, reducing the essential flow of nutrients and sediments needed to replenish the marshes. This effect, in turn, has been further accentuated by channeling of the coastal marshes to allow for oil and gas exploration and production, and improved transportation. The dissection of the coastal marshes, which was essential to the energy policy of the day, caused physical destruction and allowed the introduction of saltwater into previously freshwater marsh areas, hastening their demise.