The spillway was built in response to the Great Mississippi Flood of 1927 that inundated much of the Mississippi River basin . It was first opened during the flood of 1937 , and twelve times thereafter through February 2019 to lower river stages at New Orleans . The most recent opening began February 27 , 2019 , when river levels were predicted to rise to minor flood stage in New Orleans on March 19 , 2019 . The Army Corps of Engineers initially opened 38 of the 350 bays , and increased this number to 206 bays when the flood crest arrived later in March . The Army Corp of Engineers closed the spillway on April 11 , 2019 only to reopen it again on May 10 , 2019 . This marks the first time in the spillway 's history that it was opened twice in one year
Great Mississippi Flood of 1927
Great Mississippi Flood of 1927
Bonnet Carré Spillway