Bonnet Carré Spillway, Flood control structure in St. Charles Parish, Louisiana, United States.

The Bonnet Carré Spillway is a flood control structure along the Mississippi River with 350 bays that manage water flow. The system directs excess river water into Lake Pontchartrain during periods of high flow.

The U.S. Army Corps of Engineers built this flood management system between 1929 and 1931 in response to the devastating 1927 Mississippi River flood. The project emerged from the urgent need to better control river water flow.

Two cemeteries lie inside the floodway: Kenner Cemetery and Kugler Cemetery, holding the remains of enslaved people of African descent and free African Americans. Both are listed on the National Register of Historic Places. The spillway name comes from the small Bonnet Carré settlement; the site also saw the 1871 Bonnet Carré Crevasse, a levee breach not repaired until 1883.

The spillway is accessible by taking Highway 61 to Highway 48, then turning onto River Road in Norco. The final approach is a short drive of about one mile from this main road.

Two rail-mounted gantry cranes on top of the weir lift out the wooden needles, each 8 by 12 inches, from 350 bays; removing all 7,000 takes about 36 hours, usually spread over several days. The number of needles pulled sets the flow, and gaps at the base of each bay allow limited seepage whenever the river reaches them.