Army Corps closes final bays at Bonnet Carré Spillway
NEW ORLEANS – Based on the reduced flows in the Mississippi River at Red River Landing, the U.S. Army Corps of Engineers, New Orleans District closed the final bays of the Bonnet Carré Spillway Thursday, April 11.
The Spillway’s 13th operation began Feb. 27 and continued for another 43 days. At the Mississippi River’s peak flow 206 bays were open with a discharge of 213,000 cubic feet per second being diverted through the spillway. The Bonnet Carré Spillway is designed to ensure that a maximum river flow of 1.25 million cubic feet per second is passed through the Mississippi River and Tributaries system at New Orleans.
Although water levels are receding, allowing the structure’s closure, the Mississippi River in the New Orleans District’s area of responsibility remains elevated. Army Corps personnel will continue flood fight inspections alongside local levee districts and all levee and excavation restrictions remain in effect.
Bonnet Carré Spillway, located 28 miles above New Orleans, is a vital element of the multi-state Mississippi River and Tributaries (MR&T) system, which uses a variety of features to provide flood risk reduction to the alluvial Mississippi Valley from Cape Girardeau, MO to Head of Passes, LA. Located on the east bank in St. Charles Parish, it can divert a portion of the river's floodwaters via Lake Pontchartrain into the Gulf of Mexico, thus allowing high water to bypass New Orleans and other nearby river communities. The structure has a design capacity of 250,000 cfs, the equivalent of roughly 1,870,000 gallons per second.
The Bonnet Carré structure consists of a control structure and a floodway. The control structure is a concrete weir that parallels the river for a mile and a half. It consists of 350 gated bays, each holding 20 timber "needles," for a total of 7,000 needles. When needles are removed, river water flows into the floodway and is conveyed nearly six miles between guide levees to the lake. Operation of the structure is relatively simple. Two cranes, moving on tracks atop the structure, lift timbers from their vertical position in the weir and set them horizontally across the top of the structure to allow river water into the spillway.
Release no. 19-011