The Bonnet Carre Spillway has been opened more than a dozen times since it was constructed nearly 100 years ago, but the protection it offers New Orleans’ levee system comes at a cost: The rush of fresh water into surrounding brackish estuaries can harm the species living there, sometimes killing off entire fisheries and reefs.
As the Mississippi River continues to rise, forecasters say another opening this year is a near certainty, news that hasn’t been welcomed by all on the Gulf Coast.
A critical engineering feat of its time, it’s hard to imagine where New Orleans would be today without the spillway. But despite all the good it has done, many in south Louisiana have a complicated relationship with the long-standing structure — one that both saves and hurts so much.
A history of the spillway
The need for something like the spillway became evident after the Great Flood of 1927, when months of heavy rain across the South inundated the Mississippi River in seven states and displaced hundreds of thousands of Americans.
As the river swelled, Louisiana officials grew increasingly concerned that the levee system protecting New Orleans could break, flooding the city and causing potentially catastrophic damage…