The present state of Louisiana was underwater at the beginning of the Pleistocene epoch. The last Ice Age, which occurred around 10,000 years ago, resulted in a lowering of sea level, which exposed the northern part of Louisiana. Strong winds blew fine, silt-like material, called loess, over glaciers, and this material was carried far south. As wind speed decreased, the particles fell to the ground and formed the Louisiana Gulf Coastal Plain, in which Bayou Teche can be found.
Bayou Teche was the Mississippi River some 5,000 years ago. The Atchafalaya River Basin first began forming about 5,000 years ago when Mississippi River meandered westward of its present-day course, resulting in a succession of bayous (the Teche), rivers and natural levees that compromise today’s Atchafalaya River floodplain. A ridge of land, called the Coteau Ridge, exists along the Teche from Port Barre to New Iberia. This ridge of land formed when the Mississippi River overflowed its banks during annual floods, and the sediment that the river was carrying would deposit on the ground as the floodwaters subsided and the river returned to its own channel.
Bayou Teche is a slow-moving meandering waterway. The water is stained brown due to heavy sedimentation and brownish-red soil particles from clays in its upper reaches. As you journey toward the lower Bayou Teche south of New Iberia the bayou becomes a darker greenish brown as tea-stained organic soils from coastal marshes start to influence bayou sediment.
Water flow is slow and oxygen is low, so fisheries are limited to those fish species that can survive and propogate in slow, turbid, and low oxygenated waters (catfish, bowfin, & sunfishes). Water flow is assisted by pumps that push water from Bayou Courtableau into the headwaters of Bayou Teche at Part Barre. This down-stream flow persists until bayou waters reach the Keystone Lock and Dam which slows flow considerably. South of the Keystone Lock, water flow slows and the direction of flow can be influenced by prevailing winds. Below the town of Baldwin a large navigation canal (Charenton Canal) bisects the bayou and captures flow. This canal and coastal winds and tidal processes cause the bayou to flow upstream beyond this point. Floodgates on the Calument Cut, between the communities of Centerville and Patterson, and the navigation locks at Berwick also limit downstream flow. Below the Calument Cut, Bayou Teche merges into the Lower Atchafalaya River.
Today, the Bayou Teche is cradled within the Atchafalaya National Heritage Area. Over 250 species of birds annually use this area, including tens of thousands of nesting herons, egrets, ibises and other wading birds. This region also annually hosts some of the highest nesting concentrations of Southern Bald Eagles, Red-Shouldered Hawks, Barred Owls, Acadian Flycatchers and Prothonotary Warblers in the United States. The American alligator along with 54 other species of reptiles and amphibians can also be found. Over 90 species of fish, crawfish, crabs, and shrimp support a thriving seafood industry.
The Bayous Meander – Greg Guidroz of Bayou Vermillion Districts describes the physics behind the reason why bayous meander at The TECHE Project’s first-annual Bank-line Management Workshop.