The Bonne Carré Spillway
The Bonne Carré Spillway was constructed by the US Army Corps of Engineers in December 1935, with the aim of alleviating flooding pressure on the city of New Orleans by allowing the Mississippi River to overflow into Lake Pontchartrain. The construction was part of a multi-faceted river control project formed in response to the Flood of 1927. The spillway is located 33 miles up-river from the city of New Orleans; the site was selected for the presence of the naturally occurring Bonne Carré Crevasse. This crevasse was one of four major crevasses occurring in this area between 1849 and 1882.
The spillway is opened when flood gauges read that the river has swelled to a height of 17 feet or more, threatening to overtop the levees. In 2019, for the first time in the spillway’s history, the spillway was opened for the second consecutive year in a row. The spillway has only been opened 13 times throughout its history. The spillway imitates the natural sediment deposition patterns of the Mississippi River, with immediate adverse environmental effects as the fresh water of the Mississippi meets the brackish water of the lake. The spillway construction spans 5.7 miles, and consists of 350 concrete bays pinned with 7,000 creosote timber “needles.” When the timbers are removed one by one, the spillway allows water to flow through at a rate of 250,000 cfs (cubic feet per second).
The selection of this site is not without contestation, particularly when the plantation-era history of the landscape is considered. Two River Road communities, Montz and Sellars (now Norco), were relocated to construct the spillway, River Road is better known as “Cancer Alley” for the “Plantation to Petrochemical Plant” conversion of the landscape.
While the Corps of Engineers claims in its history of the site that the 1935 construction of the spillway was a direct response to the 1927 flood, the Krugler and Kenner cemeteries that exist in the floodplain were in use till 1929. These burials were rediscovered in 1979, when the Army Corps of Engineers began excavating the area to reinforce the spillway structure, and the remains of African Americans and Africans enslaved and free were disinterred. Construction halted in 1980, and archaeological surveys began. The site was nominated for the National Historic Register; however, to this day, little has been done to demarcate the location or relocate the remains.