The Atchafalaya Basin, or Atchafalaya Swamp (/əˌtʃæfəˈlaɪə/; Louisiana French: L'Atchafalaya, [latʃafalaˈja]), is the largest wetland and swamp in the United States. Located in south central Louisiana, it is a combination of wetlands and river delta area where the Atchafalaya River and the Gulf of Mexico converge. The river stretches from near Simmesport in the north through parts of eight parishes to the Morgan City southern area.
The Atchafalaya is different among Louisiana basins because it has a growing delta system (see illustration) with wetlands that are almost stable. The basin contains about 70% forest habitat and about 30% marsh and open water. It contains the largest contiguous block of forested wetlands remaining (about 35%) in the lower Mississippi River valley and the largest block of floodplain forest in the United States. Best known for its iconic cypress-tupelo swamps, at 260,000 acres (110,000 ha), this block of forest represents the largest remaining contiguous tract of coastal cypress in the US.
The Atchafalaya Basin and the surrounding plain of the Atchafalaya River is filled with bayous, bald cypress swamps, and marshes, which give way to brackish estuarine conditions, and end in the Spartina grass marshes where the Atchafalaya River meets the Gulf of Mexico. It includes the Lower Atchafalaya River, Wax Lake Outlet, Atchafalaya Bay, and the Atchafalaya River and bayous Chêne, Boeuf, and Black navigation channel. See maps and photo views of the Atchafalaya Deltas centered on .
The basin, which is susceptible to long periods of deep flooding, is sparsely inhabited. The Basin is about 20 miles (32 km) in width from east to west and 150 miles (240 km) in length. The Basin is the largest existing wetland in the United States with an area of 1,400,000 acres (5,700 km2), including the surrounding swamps outside of the levees that historically were connected to the Basin. The Basin contains nationally significant expanses of bottomland hardwoods, swamplands, bayous, and back-water lakes. The Basin's thousands of acres of forest and farmland are home to the Louisiana black bear (Ursus americanus luteolus), which has been on the United States Fish and Wildlife Service threatened list since 1992.
The few roads that cross the Basin follow the tops of levees. Interstate 10 crosses the basin on elevated pillars on a continuous 18.2 mile (29,290 m) bridge from Grosse Tete, Louisiana, to Henderson, Louisiana, near the Whiskey River Pilot Channel at .
The Atchafalaya Basin has a long relationship with the Mississippi River throughout the Holocene epoch, and the geology of the modern basin is a direct manifestation of that relationship. The Atchafalaya Basin has been part of three historic depositional lobes (Sale-Cypremort, Teche, and Lafourche lobes) of the Mississippi River Delta Plain that formed south Louisiana, and active delta lobe development is currently occurring at the mouth of the Atchafalaya River and Wax Lake Outlet. The geology of the current basin has been driven by flows of Atchafalaya River water and sediment that flowed into open water areas through relict Mississippi River distributary channels.
The Atchafalaya Basin contains lacustrine and coastal delta landscapes. Natural filling of the basin with sediment was accentuated with the building of the flood control levees that were completed in the 1940s. After the levees, sediment was directed into an area about one-third the size of the original basin. An example of the lacustrine delta development can be seen at Lake Fausse Pointe State Park, where levees severed the connection between the Grand Bayou distributary and the lake, and delta development was frozen in time.
Geologically, the Atchafalaya River has been a backswamp, low area between the paths of the Mississippi River through the process of delta switching, which has built the extensive delta plain of Louisiana. The natural levees of the Mississippi River (on the east) and the levees along its previous course (now Bayou Teche) on the west define the Atchafalaya Basin. The central basin is further bordered by man-made levees designed to contain and funnel floodwaters released from the Mississippi at the Old River Control Structure and the Morganza Spillway south toward Morgan City and eventually to the Gulf of Mexico. Historically there were small and few channel connections to the Mississippi River. The historic lack of significant channel connection indicates that the Atchafalaya River Basin did not receive significant sediment from the Mississippi except during large floods.
During the mid-19th century, manmade channel alterations, including the removal of a large log jam and dredging, permanently connected the Atchafalaya River to the Mississippi River. From then until the completion of the Old River Control Structure in 1963, the Mississippi was increasingly diverting flow into the shorter and steeper path of the Atchafalaya channel. By law, a regulated 30 percent of the latitudinal flow water from the Mississippi, Red and Black rivers is diverted into the Atchafalaya at the Old River Control Structure. This flow diverts on average 25 percent of the Mississippi River flow down the Atchafalaya.
In times of extreme flooding, the US Army Corps of Engineers may open the Morganza Spillway and other spillways to relieve pressure on levees and control structures along the Mississippi. On May 13, 2011, in the face of a rising Mississippi River that threatened to flood New Orleans and other heavily populated parts of Louisiana, the USACE ordered the Morganza Spillway opened for the first time since 1973. This water floods the Atchafalaya Basin between the levees along the western and eastern limits of the Morganza and Atchafalaya basin floodways.
The control of the river's floods, along with those of the Mississippi River, has become a controversial issue in recent decades. The US Geological Survey (USGS) reports that Mississippi River delta salt marshes are wetlands degrading at a rate of 29 square miles per year. The Atchafalaya River Deltas are the only locations of land growth along the Louisiana Gulf Coast.
During the early 20th century, the Atchafalaya River Basin was designated as a spillway for floods of the Mississippi River. In order to facilitate this emergency plan without flooding adjacent agriculture and towns, protective levees were built dividing the Atchafalaya Basin Floodway from large portions of the historic swamp boundaries. A central channel was dredged through some existing channels and in some places through swamp forest. At that point the isolated Atchaflaya River Basin was permanently connected to a very large, sediment-rich river.
From 1850 to 1950 open water decreased from 490 km² to 290 km². From 1950 to 2005 the amount of open water decreased to 190 km². When the Atchafalaya Basin flow plan was implemented (1950–1974), 30 percent of the total Atchafalaya River flow was designated to be directed off the main channel, 15 percent to the east and 15 percent to the west side. As a result of the Atchafalaya River channel bed incision, in the early 21st century the flow distribution is 13 percent of the total flow, with a flow distribution of 7 percent to the east side and 6 percent to the west side as reported by the USGS. This decrease in flow across the floodplain, in conjunction with high organic deposition from trees and floating vegetation and high water temperature, has resulted in large areas of low-dissolved oxygen water. Where once the water was black (1850), the water became brown (1927). Where the water was formerly brown (1927), it is now black (2009).
During the period of 1960–1980, oil and gas exploration and development in Louisiana increased dramatically. Numerous large access canals and pipeline canals were dredged through deep swamp areas, across bayous, and across the Atchafalaya River. In some areas of the Basin, there are 2 km or more of access canals to every 1 km of natural bayou. These large channels (30–50 m wide by 2–3 m deep) have fundamentally changed the hydrology of the swamps. Deep swamp areas that were hydraulically isolated from sediment were connected directly to the river and its sediment and suffered rapid filling. The USGS has measured sediment deposition rates of up to 30 cm per year where these channels enter open water, and 4 cm per year on adjacent floodplains. In some places natural bayous have filled in due to flow capture by access canals.
Spoil material from the canals was deposited adjacent to the canals, further impeding the natural flow across the floodplain.
From 1830 to 1953, the community of Bayou Chene thrived as a center for logging, hunting, trapping, and fishing in the heart of the Atchafalaya Basin. Now buried underneath at least twelve feet of silt, Bayou Chene is one of several abandoned communities in the midst of the basin.
The earliest settlers of the Bayou Chene region were the native Chitimacha tribe. Several villages important to the Chitimacha were located around Bayou Chene including the Village of Bones or Namu Katsi and the Cottonwood Village, known as Kushuh Namu in the Chitimacha language. One of the earliest written accounts of the Bayou Chene region comes from French explorer C.C. Robin who, while paddling through the Basin in 1803, wrote:
"After long sinuosities which form innumerable islands, among which the inexperienced traveler would require the thread of Ariadne in order not to wander forever, the river opens suddenly into a magnificent lake of several leagues extent. The sudden light surprises the traveler and the beauty of the water, set about with tall trees, forms an enchanting sight."
By 1841, between fifteen and twenty families were farming along the banks of "Oak Bayou" or Bayou Chene. The population rose quickly over the next twenty years, as the United States Census of 1860 counted 675 residents in the community. By the 1870s, a majority of those living along Bayou Chene were involved in logging bald cypress, tupelo, and other bottomland hardwoods in the basin.
By the early twentieth century, Bayou Chene was the center of the Atchafalya Basin's cypress and fur industry and housed many of the 1,000 full-time fisherman who fished the swamp's shallow bottoms. Writing about her family's experiences in the region, Gwen Roland describes how the community relied upon the basin's waters for everything, including transportation:
"Out here on the Chene, our skiffs flare out on the sides so they float high like an acorn cap; it makes them quick to steer with an extra push on one oar or the other. This skiff floated deep and straight like a water trough or a coffin."
The Great Mississippi Flood of 1927 nearly demolished the community. Rising seven feet above natural levees, the floodwaters inundated Bayou Chene for weeks. Local folklore says a village goat survived in the Methodist Church during this period on hymnals and wallpaper.
The Great Depression hit the residents of Bayou Chene hard, but many former residents look fondly on the massive flood control projects promulgated by the U.S. Army Corps of Engineers that provided gainful employment during the period. As a result of the 1927 flood, the entire Atchafalaya Basin was designated an official floodway and a series of man-made levees were built that would permanently alter flooding patterns in the region. Further flooding in 1937 encouraged many residents to move their homes to higher ground, but even these measures were not enough to protect the community from annual flooding. After years of rising waters, the community came to an end with the closing of the United States Post Office at Bayou Chene in 1952. Most of Bayou Chene's former residents relocated to the fringes of the basin in towns like New Iberia, St. Martinville, and Breaux Bridge. Today, little remains of the swamp community buried underneath the murky waters of the Atchafalaya.
The Mississippi River floods in April and May 2011 were among the largest and most damaging recorded along the U.S. waterway in the past century, comparable in extent to the major floods of 1927 and 1993. In April 2011, two major storm systems deposited record levels of rainfall on the Mississippi River watershed. When that additional water combined with the springtime snowmelt, the river and many of its tributaries began to swell to record levels by the beginning of May. Areas along the Mississippi itself experiencing flooding included Illinois, Missouri, Kentucky, Tennessee, Arkansas, Mississippi, and Louisiana.
U.S. President Barack Obama declared the western counties of Kentucky, Tennessee, and Mississippi federal disaster areas. For the first time in 37 years, the Morganza Spillway was opened on May 14, deliberately flooding 4,600 square miles (12,000 km2) of rural Louisiana to save most of Baton Rouge and New Orleans.Fourteen people were killed in Arkansas, with 392 killed across seven states in the preceding storms. Thousands of homes were ordered evacuated, including over 1,300 in Memphis, and more than 24,500 in Louisiana and Mississippi, though some people disregarded mandatory evacuation orders. The flood crested in Memphis on May 10 and artificially crested in southern Louisiana on May 15, a week earlier than it would have if spillways had not been opened. The United States Army Corps of Engineers stated that an area in Louisiana between Simmesport and Baton Rouge was expected to be inundated with 20–30 feet (6.1–9.1 m) of water. Baton Rouge, New Orleans, and many other river towns were threatened, but officials stressed that they should be able to avoid catastrophic flooding.
From April 14–16, the storm system responsible for one of the largest tornado outbreaks in U.S. history also produced large amounts of rainfall across the southern and midwestern United States. Two more storm systems, each with heavy rain and tornadoes, hit in the third week of April. In the fourth week of April, from April 25–28, another, even more extensive and deadly storm system passed through the Mississippi Valley dumping more rainfall resulting in deadly flash floods. The unprecedented extensive rainfall from these four storms, combined with springtime snow melt from the Upper Midwest, created the perfect situation for a 500-year flood along the Mississippi.Atchafalaya
The word Atchafalaya derives from the Choctaw term hacha falaia, meaning "long river".
Atchafalaya may refer to:
Atchafalaya River, Louisiana, U.S.
Atchafalaya Basin or Atchafalaya Swamp, wetlands surrounding the lower part of the Atchafalaya River, Louisiana
Atchafalaya Basin Bridge
Atchafalaya Swamp Freeway, a portion of Interstate 10 in Louisiana that includes the bridge
Atchafalaya National Heritage Area
Atchafalaya National Wildlife Refuge
Atchafalaya Golf Course at Idlewild, Patterson, Louisiana
A song from the album Sylva, by jazz ensemble Snarky PuppyAtchafalaya Basin Bridge
The Atchafalaya Basin Bridge, also known as the Louisiana Airborne Memorial Bridge, is a pair of parallel bridges in the U.S. state of Louisiana between Baton Rouge and Lafayette which carries Interstate 10 over the Atchafalaya Basin. With a total length of 96,095 feet (29,290 m) or 18.2 miles, it is the 3rd longest bridge in the US and the 2nd longest on the interstate system and fourteenth-longest in the world by total length.
The bridge was opened to the public in 1973, construction was said to have begun in 1971. At the time of its completion, it was the longest bridge in the United States.
The bridge includes two exits: one for Whiskey Bay (Louisiana Highway 975) and another for Butte La Rose (LA 3177). While the bridges run parallel for most of their length, they merge when crossing the Whiskey Bay Pilot Channel and the Atchafalaya River. The average daily traffic count is (as of 2015) 30,420 vehicles.
Accidents occur frequently near the two river crossings as both are very narrow and lack shoulders. Accidents along the bridge can be problematic as the Atchafalaya Basin is sparsely inhabited. In 1999, Governor Mike Foster lowered the speed limit on the bridge from 70 MPH to 60 MPH. In 2003, the Louisiana Legislature enacted new traffic regulations for the bridge. The speed limit for 18-wheelers was lowered to 55 MPH, and they must remain in the right lane while crossing the bridge.Atchafalaya Basin Mounds
The Atchafalaya Basin Mounds (16 SMY 10) (variously known as the Patterson Mounds, Patterson site, Moro Plantation Mounds and as the protohistoric village of Qiteet Kuti´ngi Na´mu by the Chitimacha Tribe of Louisiana) is an archaeological site originally occupied by peoples of the Coastal Coles Creek and Plaquemine cultures beginning around 980 CE, and by their presumed historic period descendants, the Chitimacha, during the 18th century. It is located in St. Mary Parish, Louisiana on the northern bank of Bayou Teche at its confluence with the Lower Atchafalaya River. It consists of several earthen platform mounds and a shell midden situated around a central plaza. The site was visited by Clarence Bloomfield Moore in 1913.Atchafalaya Golf Course at Idlewild
The Atchafalaya Golf Course at Idlewild is an 18-hole championship public golf course in the southern United States, located in Patterson, Louisiana in the Atchafalaya Basin. It is a par-72 7,078 yards (6,472 m) course from the gator tees.Atchafalaya National Heritage Area
Atchafalaya National Heritage Area is a federally designated National Heritage Area encompassing parts of fourteen parishes along the Atchafalaya River in the U.S. State of Louisiana. The heritage area extends the length of the Atchafalaya Basin from the area of Ferriday in the north to the river's mouth beyond Morgan City. The National Heritage Area is divided into four regions: Upper, Between 2 Rivers, Bayou Teche Corridor and the Coastal Zone. The designation provides a framework for the promotion and interpretation of the area's cultural and historic character, and the preservation of the natural and built environment. The heritage area designation recognizes the area's unique environment and culture, and its contributions to music, English and French language, literature, and cuisine.Major locales included in the Heritage Area include Avery Island, New Iberia, Morgan City, Lafayette, Opelousas, Baton Rouge, Plaquemine and Houma. Jean Lafitte National Historical Park, Longfellow-Evangeline State Historic Site and Plaquemine Lock State Historic Site are included in the heritage area, as well as the Louisiana State Museum branches in Baton Rouge and Patterson. Parishes partly or wholly included in the area include Concordia, Avoyelles, Pointe Coupee, St. Landry, Lafayette, St. Martin, Iberia, East Baton Rouge, Ascension, West Baton Rouge, Iberville, St. Mary, Assumption and Terrebonne parishes.The National Heritage Area was authorized by Public Law 109-338, also known as the National Heritage Area Act of 2006.Atchafalaya National Wildlife Refuge
The Atchafalaya National Wildlife Refuge is located about 30 miles (48 km) west of Baton Rouge, Louisiana, and one mile (1.6 km) east of Krotz Springs, Louisiana, lies just east of the Atchafalaya River. In 1988 under the administration of Governor Foster the "Atchafalaya Basin Master Plan" was implemented that combined the 11,780-acre (4,770 ha) Sherburne Wildlife Management Area (WMA), the 15,220-acre (6,160 ha) Atchafalaya National Wildlife Refuge, and the 17,000-acre (6,900 ha) U.S. Army Corps of Engineers' Bayou Des Ourses (Bayou of the Bears) into the Sherburne Complex Wildlife Management Area.Atchafalaya River
The Atchafalaya River is a 137-mile-long (220 km)distributary of the Mississippi River and Red River in south central Louisiana in the United States. It flows south, just west of the Mississippi River, and is the fifth largest river in North America, by discharge. The name "Atchafalaya" comes from Choctaw for "long river", from hachcha, "river", and falaya, "long".Bayou Chene, Louisiana
Bayou Chene (translated to Oak Bayou) was previously a small unincorporated community in St. Martin Parish, Louisiana, United States. The community was located in the Atchafalaya Basin.Butte La Rose, Louisiana
Butte La Rose (also known as Butte-à-la-Rose) is an unincorporated community in St. Martin Parish, Louisiana, United States.KYFJ
KYFJ is a radio station serving the Lafayette and Baton Rouge areas. The station broadcasts at 93.7 MHz with 100 kW and is licensed to New Iberia, Louisiana. KYFJ is currently under ownership of Bible Broadcasting Network. It was previously held by The Last Bastion Station Trust, LLC, who picked up this station after its previous owner Citadel Broadcasting swapped the station for KNEK-FM. The station's transmitter is located in the Atchafalaya Basin area in rural St. Martin Parish.Lake Fausse Pointe State Park
Lake Fausse Pointe State Park is located in Iberia Parish, Louisiana and St. Martin Parish, Louisiana, USA. It is located about 18 miles (29 km) east of St. Martinville adjacent to the Atchafalaya Basin. The park is 6,000 acres (2,400 ha) in size and was once the home of the Chitimacha Indians.Mike Foster (American politician)
Murphy James "Mike" Foster Jr. (born July 11, 1930) served as the 53rd governor of Louisiana from January 1996 until January 2004. Foster is a businessman, landowner, and sportsman in St. Mary Parish in the sugar-growing section of the southern portion of the state.Morganza Spillway
The Morganza Spillway or Morganza Control Structure is a flood-control structure in the U.S. state of Louisiana along the western bank of the Lower Mississippi River at river mile 280, near Morganza in Pointe Coupee Parish. The spillway stands between the Mississippi and the Morganza Floodway, which leads to the Atchafalaya Basin and the Atchafalaya River in south-central Louisiana. Its purpose is to divert water from the Mississippi River during major flood events by flooding the Atchafalaya Basin, including the Atchafalaya River and the Atchafalaya Swamp. The spillway and adjacent levees also help prevent the Mississippi from changing its present course through the major port cities of Baton Rouge and New Orleans to a new course down the Atchafalaya River to the Gulf of Mexico. The Morganza Spillway, operated by the U.S. Army Corps of Engineers, was opened during the 1973 and 2011 Mississippi River floods.Old River Control Structure
The Old River Control Structure is a floodgate system in a branch of the Mississippi River in central Louisiana. It regulates the flow of water leaving the Mississippi into the Atchafalaya River, thereby preventing the Mississippi river from changing course. Completed in 1963, the complex was built by the U.S. Army Corps of Engineers in a side channel of the Mississippi known as "Old River", between the Mississippi's current channel and the Atchafalaya Basin, a former channel of the Mississippi. The Old River Control Structure is actually a complex containing the original low-sill and overbank structures, as well as the auxiliary structure that was constructed after the low-sill structure was damaged during the Mississippi River Flood of 1973. The complex also contains a navigation lock and the Sidney A. Murray Jr. Hydroelectric Station.Plaquemine Lock State Historic Site
Plaquemine Lock State Historic Site, located in Plaquemine, Louisiana, commemorates an early example of hydraulic engineering design and the historic significance of Bayou Plaquemine, an important navigable waterway that was once a distributary of the Mississippi River. Bayou Plaquemine promoted settlement beginning in the 18th century and helped the area economically by providing an access route between southwestern Louisiana (and thus Texas) and the Mississippi via the Atchafalaya Basin.
The lock itself was designed by Colonel George Washington Goethals of the United States Army Corps of Engineers, who later served as chief engineer of the construction of the Panama Canal Lock, and went on to be the Canal Zone's first governor. Plaquemine Lock was opened on April 9, 1909 after 14 years of construction. When it was built, Plaquemine Lock was the highest freshwater lift of any lock in the world. The lock initially utilized a gravity-flow principle until pumps were installed years later.
The lock was closed after 52 years of service in 1961 due to increased river traffic and the demand for a larger lock, which opened thereafter in Port Allen. The Plaquemine Lock structure was placed on the National Register of Historic Places in 1972. Today, the Gary James Hebert Memorial Lockhouse serves as an on-site museum and visitors center. It is named for the man who led the way to help preserve the Lock site, which today covers 19 acres (7.7 ha).Sandra Thompson (politician)
Sandra Smith "Sandy" Thompson (born October 4, 1946) is a former Louisiana state administrator, who retired in 2007 from the directorship of the Atchafalaya Basin Program.Sherburne Complex Wildlife Management Area
The Sherburne Complex is a joint land management venture of the U.S. Fish and Wildlife Service, the Louisiana Department of Wildlife and Fisheries (LDWF), and the U.S. Army Corps of Engineers that began in 1983. The area consists of 44,000 acres (180 km2), and is managed by the Louisiana Department of Wildlife and Fisheries. The complex is located in the Morganza Flood way system of the Atchafalaya Basin about 30 miles (48 km) west of Baton Rouge, Louisiana and actually extends a little south of the I-10 Atchafalaya Basin Bridge at Whiskey Bay, Louisiana. The bridge crosses the Whiskey Bay Pilot Channel. Located on the graveled LA 975, the west boundary is on the east side of the Atchafalaya River with the east boundary being the East Protection Levee. The complex stretches just north of old highway 190, and a short distance to the south of I-10. The nearest town is Krotz Springs to the north off US 190.West Atchafalaya Floodway
The West Atchafalaya Floodway is a flood control structure of the Mississippi River and Tributaries Project located in the Lower Atchafalaya Basin in south-central Louisiana. It has a project design flood flow capacity of 250,000 cu ft/s (7,100 m3/s).