Louisiana contains approximately 40 percent of the coastal wetlands found in the lower 48 states, and about 80 percent of the wetlands lost.  The wetland losses have reached up to 40 square miles of marsh a year. Losses during 1978 through 1990 indicate a loss of about 35 square miles a year of freshwater and non-freshwater marshes and forested and scrub-shrub wetlands. That equates to a total 12-year loss of about 420 square miles, an area equal to twice the size of the populated greater New Orleans area. Prior to 1990, both urbanization and hurricane damage contributed equally to wetland losses in Louisiana. By the year 2040 an additional 800,000 acres of wetlands will disappear, and the Louisiana shoreline will advance inland as much as 33 miles in some areas. This realization prompted Congress to pass the Coastal Wetlands Planning, Protection and Restoration Act (CWPPRA) in 1990. The act funds wetland projects nationwide, and has designated approximately $60 million for work in Louisiana each year.
The wetlands of Louisiana are water-saturated coastal and swamp regions of southern Louisiana. The Environmental Protection Agency ("EPA") 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 basin to the Gulf of Mexico for the Lower Mississippi River Delta, which 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 30 miles at the most, then the elevation begins to increase and the marshes fade into upland prairies. 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.
Prior to the early 20th century and the advent of human engineering of the waterways of the Lower Mississippi Watershed, soil and sediment was replenished annually during the spring floods. The seasonal flooding that previously provided sediments critical to the healthy growth of wetlands has been virtually eliminated by construction of massive levees. Flooding over the banks, the river deposited silt and sediment on the marsh or swamp floor after receding. Over time, the sediment accumulated, creating a nutrient rich soil, promoting rapid plant growth. Levees and armored riverbanks now channel the river for approximately 2000 kilometers; sediment carried by the river is now discharged far from the coast, depriving wetlands of silt and nutrients needed to replenish and nourish areas affected by the tides or sea level rise.
Besides the loss of sediment, an extensive system of dredged canals and flood-control structures, constructed to facilitate hydrocarbon exploration and production as well as commercial and recreational boat traffic, has enabled salt water from the Gulf of Mexico to intrude brackish and freshwater wetlands. Moreover, forced drainage of the wetlands to accommodate development and agriculture also contribute to wetlands deterioration and loss.
2010 BP Oil Spill
The April 2010 explosion on the BP Deepwater Horizon offshore oil rig has released an estimated 5,000 to 25,000 barrels per day of crude oil from the drilling platform. The leak will have a considerable long-term effect on the wetlands of Louisiana and surrounding states.
Wetland loss along the Louisiana coastal zone has long been recognized as one of the state’s most pressing environmental problems. Of the numerous factors contributing to this loss, perhaps the leveeing of the Mississippi River for flood control has had the most far-reaching impact, blocking the river’s historic spring overflows and thus impeding the rush of marsh-supporting fresh water, nutrients and sediment to the coastal zone.
The many benefits of the wetlands found in this region were not recognized by a majority of policy makers early in the 20th century. These areas, which sit above the most fertile oil and gas fields in the continental United States, were viewed as wasted land that hindered development and progress.
Beginning in 1930, an extensive levee system aided by locks and dams was developed in the waterways of the Mississippi River and surrounding tributaries. 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.
Prior to the building of levees on the Mississippi River, the wetlands were maintained and fed by annual spring flooding, filling the area with silt and sediment, slowly adding layer upon layer of rich soil. Disrupting the equilibrium by not allowing the occasional flood to feed the wetlands additional silt and sediment, the existing soil will slowly wash away, leading to wetland erosion. After the levees were built, flood sediment was directed directly into the Gulf of Mexico, bypassing the wetlands upstream. 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 canal's built in the area, caused decline of the wetlands and also caused less weakening of recent hurricanes such as Hurricane Katrina. In 2009, a study released detailing that the efforts to increase sedimentation by allowing sediment from the Mississippi to reach the Louisiana Coast may not be sufficient to halt or reverse wetland losses, considering the amount of sediment required and the increase in sea levels due to global warming. According to the study, there are over 8,000 dams in the Mississippi drainage basin, trapping approximately 50% of the sediment needed to halt coastal wetland erosion in Lousiana. 
Dwindling sediment deposition is not the only reason for wetland loss in Louisiana. Nutria, and invasive rodent from South American, denudes the marsh vegetation. Loss of the marsh vegetation is often permanent, and the wetland will typically fall apart. A 1996 study determined damage from Nutria over a 128 square mile area in the Barataria-Terrebonne Basin. Since 1996, Nutria damage has decreased to an estimated 6,171 acres, primarily due to the The Coastwide Nutria Control Program, which pays a bounty of $5 per nutria tail.  
Southern Louisiana’s disappearing wetlands have a broad impact ranging from cultural to economic. In Louisiana, commercial fishing accounts for more than $300 million of the state's economy. More than 70% of that amount stems from species such as shrimp, oysters and blue crab's 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. 
Due to the extensive damage from Hurricane Katrina, wetland preservation and restoration in Louisiana has taken on a more critical and prominent role in Louisiana, although it has been an important environmental issue since the 1960's. Below are some of the projects that have been implemented or proposed to stop, minimize or reverse wetland loss in Louisiana.
In 1998, Federal, State and local partners agreed on a $14 billion framework with 77 projects over a time span of 50 years for coastal wetlands restoration, management and priorities outlined in "2050: Toward a Sustainable Coastal Louisiana". As outlined in the agreement, the Barataria Basin was identified as an area needing the most immediate attention, and in 2000, the Army Corps of Engineers and Louisiana Department of Natural Resources signed an agreement to start restoring the wetlands in the Barataria Basin, due to the high rate of wetland loss, and potential for successful restoration due to the sediment available for deposition from the Mississippi River and adjacent bays. Other strategies proposed in the agreement include barrier shoreline restoration, marsh creation via water and sediment diversion from the Mississippi River.  The end result of the Coast 2050 was to restore and protect 450,000 acres of wetlands. Congress had not approved the Coast 2050 plan, and when hurricanes Rita and Katrina hit, Congress was studying a less costly, scaled down proposal which could be initiated in the span of a decade. 
Davis Pond Freshwater Diversion Structure
Approved for construction in the 1960's the Davis Pond diversion finally became operational in 2005, due to lawsuits filed by fishermen and residents who feared the flooding would damage their fishing grounds and property.  At a cost of $119.6 million, the diversion project has reintroduced fresh water, nutrients and sediment from the Mississippi River to the shrinking and salt-threatened Barataria estuary. Up to 10,000 cubic feet/second of water flows through a ponding area and then into the project’s 10,084 acres, where the sediment settles.  However, since its dedication in 2002, its capacity has not been utilized; in 2003- 2005 it averaged less than 1,000 cfm annually, and in years 2006-2008 it has averaged approximately 3,000 cfm throughout the year. 
Opened in 1991, the Caernarvon Diversion is 15 miles downriver from New Orleans and has the capacity to divert up 8,000 cubic feet of water and sediment per second.
Fifty years after digging the Mississippi River-Gulf Outlet shipping passage and destroying vast wetland areas, the Army Corps of Engineers is planning to restore the damage the channel caused to the wetlands surrounding New Orleans. The Mississippi River-Gulf Outlet was dug in the 1950s as a shortcut between the Gulf of Mexico and New Orleans, but was never widely used for shipping, primarily because the ships had to pass through a set of locks on their way to the ports on the Mississippi River. The shipping channel has been widely believed to have adversely affected the marshes and swamp forests through salt water infiltration and erosion. As a first step the Corps plans to hire contractors to plug the channel with rocks by June 2009, and then move forward with a restoration plan for the affected wetlands. Others  believe that the lack of hard scientific data on storm surge and the extent wetlands can reduce or minimize storm impacts is unknown at this time.
As of April 2009, during a trial against the Federal Government and the Army Corps of Engineers, a geologist stated that the Mississippi River-Gulf Outlet did have a detrimental effect on the surrounding wetlands by allowing salt and brackish water infiltration. The damage was compounded by the subsequent widening of the channel. If a decision is made for the plaintiff, it potentially allows other Katrina flood victims to press their case against the Federal Government and the Corps of Engineers. A similar case was dismissed last year as a standing Federal Law does not allow the Corps to be sued for flood damage. 
In April 2009, a unique project, the Mississippi River Sediment Delivery System has been unveiled to channel dredged sediment from the Mississippi River to the wetlands in South Louisiana to restore 474 acres of tidal marsh. Approximately 200 million tons of sediment flows down the Mississippi Roiver annually, of which the the Army Corps of Engineers dredges about 60 million cubic yards of the sediment to maintain Louisiana's waterways. Typically very little of the dredged mud was deposited to build up the diminishing wetlands. According to the project documents, if successful, the Sediment Delivery system could potentially create 18 square miles of marsh a year and reduce wetland losses by as much as two-thirds.
The dredged sediment will be piped to Bayou Dupont via a 1 meter pipe, to an 500 acre area of open water and broken marsh.  Once the area has been adequately filled, it will be planted with marsh grasses.  It is estimated that the project will cost $28 million and be completed by August 2009.
The Coastal Wetlands Planning, Protection and Restoration Act of 1990 (CWPPRA)authorized the Fish and Wildlife Service to participate in the development and oversight of a coastal wetlands conservation program for Louisiana and take the lead role in a 50/50 matching grant program for wetlands outside of Louisiana. It is now the primary program in Louisiana for combating wetland loss. Parallel authority is granted to the Corps of Engineers and EPA to work with the State of Louisiana to develop, review, approve and evaluate the State's Coastal Wetlands Conservation Plan. This Plan is to achieve a goal of "no net loss of wetlands" in coastal Louisiana through a combination of regulatory and nonregulatory measures. The Act also authorizes the Federal government to pay up to 75 percent of project costs. In 2004, Congress reauthorized the funding for the CWPPRA program through 2019.
The Lake Pontchartrain Basin (LPB) Restoration Act of 2000 has budgeted $20 million per year as a regional effort to support the restoration activities of the parishes surrounding Lake Pontchartrain. The major environmental challenges to the LPB are urban runoff, urbanization, sewage, wetland loss, saltwater intrusion and agricultural runoff. Many of these challenges have been met by reducing urban runoff and untreated or poorly treated sewage by re-routing stormwater discharges away from the Lake, the use of retention lagoons for minimizing the inflow of agricultural waste, the creation of buffer zones, and the banning of shell dredging in 1990. 
The Atchafalaya Basin is the 135 mile long basin of the Atchafalaya River, encompassing approximately 1.4 million acres emptying into Gulf of Mexico. It contains the largest contiguous bottomland hardwood forest in North America, and is a prime wintering habitat for waterfowl; as it is situated directly in the North American Central Flyway, and provides necessary habitat for migratory birds. 
The Atchafalaya Basin it is the only growing delta in Louisiana. Total wetland acreage lost between 1932 and 1990 is approximately 3,760 acres. The average loss from 1974 through 1990 is 87 acres per year in the northern region.
The Atchafalaya Basin can be divided into three distinct areas, Northern, Middle and Southern; each with distinctly different ecosystems. The northern part is 885,000 acres of bottomland hardwood forest, making this area the largest river swamp in North America.  The middle, sandwiched between the Northern hardwood forests and the lower marshes is cypress swamps. The Atchafalaya is also considered the most productive swamp in the North American, up to 3 times as productive as the Everglades.