Some years, the Bonnet Carre Spillway opens to alleviate flooding along the Mississippi River. This year’s opening of the spillway is the 13th in its 80-year history and the first time it has opened in back-to-back years.
The spillway structure, located more than 20 miles upriver from New Orleans, features 350 “bays” that open, allowing floodwater from the river to spill into nearby Lake Pontchartrain. This causes the Mississippi River’s level to decrease, removing potential river flooding issues for New Orleans.
Openings last anywhere from 13 to 75 days. In 2018, the spillway opened for 30 days.
– Alexandra Cranford, WWL-TV