Bonnet Carre Spillway

The Mississippi River provides a major transportation route for raw materials and manufactured goods from the interior of the country, and drains approximately 41% of the contiguous United States, including all or parts of thirty-one states and two Canadian provinces. In the late 1800s and early 1900s, the federal flood control policy was “levees-only.” However, when miles of levees failed during the Great Flood of 1927, inundating large swaths of surrounding land, a new policy of spillways and relief structures emerged. The Bonnet Carré Spillway project, arguably more than any other structure or project, symbolizes that change from the traditional “levees-only” to levees and floodways. 

Before its construction between 1929 and 1931, large scale flood control projects were not considered viable options, therefore, many of the techniques, materials, and design concepts were innovations. The size of the structure itself was unprecedented. The U.S. Army Corps of Engineers performed hydraulic studies prior to the design and construction of the Bonnet Carré Spillway, significantly advancing the hydraulic efficiency of its weirs. In addition, significant advances in the engineering of movable dams in which weir and needle dams were parts of the design. Finally, coupled with tight quality control during construction, the concrete used in the construction provided advances in concrete strength and mix design.