Atchafalaya River at Atchafalaya Welcome Center

What's the Story?

The Atchafalaya Basin is one of the most extensive river-floodplain systems in the world. It is also an important floodway system made up of three individual sections—the West Atchafalaya Floodway, the Morganza Floodway and the Lower Atchafalaya Floodway—all which help protect millions of Americans from flooding. The system is surrounded by levees that direct water from the Mississippi River through the Basin to the Gulf of Mexico. It regulates the combined flow of the Red and Mississippi rivers down the Atchafalaya River at the Old River Control Structure near Simmesport and was designed to handle half of the Project Design Flood, the maximum probable Mississippi River flood.

The levees that surround this section of the Basin (the Lower Atchafalaya Floodway) are about 15 miles apart and were built in the 1930s. Their construction—and the straightening of the Atchafalaya River in this area—forever changed the Basin, both inside and outside the floodway. The river’s new main passage, for example, follows the man-made Whiskey Bay Pilot Channel, while the previous channel through Butte La Rose is silting in. Additionally, some historic segments were cut off by the levees and others were intentionally closed to force the bulk of Basin water down the new channel, making it wider and deeper in compliance with the flood control mandate. This also improved river navigation.

Building levees increased the height of flooding inside the Basin and removed some traditional drainage paths from adjacent areas. Higher flood levels inside the levees also forced permanent migration of residents from small communities such as Atchafalaya, which sprouted in the early 1900s (where the I-10 Butte La Rose exit is now) to support the Southern Pacific Railroad bridge (destroyed in the Flood of 1927) between Lafayette to Baton Rouge. 

Low areas outside the levees also saw increased flooding as rainwater in upper parts of the traditional Basin moved through a restricted path and land subsided without annual replenishment from river sediment. By the 1970s, deltas in the floodway’s lakes were largely complete. During the Mississippi River Flood of 1973, a new Atchafalaya Delta began emerging far downstream in Atchafalaya Bay. It continues to grow. 

The 18-mile Interstate 10 bridge was completed in the 1970s, connecting both sides of the Basin once again. Today, this biodiverse wetland is a source of livelihood for many fishermen and hunters, and a recreation destination for others. It is host to the largest block of forested wetlands in the lower Mississippi River valley, the largest block of coastal cypress forest in the U.S., and is a habitat for more than 85 species of fish and almost 300 species of resident and migratory birds. Challenges to sustaining this area include hydrology effects, sedimentation, invasive species and resource extraction.

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This site’s geology/geomorphology: Holocene natural levee deposits of Atchafalaya River

 

Site GPS Coordinates: 30.342385, -91.719988
Closest Address: 1908 Atchafalaya River Hwy., Breaux Bridge, LA 70517
Driving Directions: From Baton Rouge, take I-10 W. toward Lafayette. Take Exit 121, then turn right onto LA 3177 S. The destination will be shortly after on the right.