Lake Pontchartrain

What happens to the Lake Pontchartrain and the wetlands when the Bonnet Carré Spillway is opened during high river stages?

During high river stages, it becomes necessary to open the Bonnet Carré Spillway to divert waters from the Mississippi River into Lake Pontchartrain and the wetlands.

Diverting water from the river presents environmental hazards for Lake Pontchartrain because of the immersion of fresh water into the salty lake water. During previous openings, toxic blue-green algae blooms have developed on parts of the lake. A team comprised of the Army Corp of Engineers, the Lake Pontchartrain Basin Foundation, as well as State and Federal Environmental Agencies, will monitor the effects of the river water pouring into the lake. Airboats manned with fishermen will be ready to catch, tag, and release fresh water fish species that inadvertently land in the lake back into the river below the spillway.

However, the sediment from the river flooding the wetlands acts to rebuild depleted areas ravaged by the saltwater intrusion of the Gulf of Mexico.

Prior to the intricate levee system built after the Great Flood of 1927, the Mississippi meandered and changed course, feeding the wetlands and leaving behind alluvial soil creating rich farmland.

It was the absence of the levee system that created the coastline and barrier islands Louisianians once knew. Oddly enough, it’s the levee system of the lower Mississippi that contributes to the disappearance of the Louisiana coastline. It is believed that the construction of a permanent diversion of river water known as the Mid-Barataria Canal, to be completed by the end of this decade, will be integral in coastal restoration. It will allow the Mississippi River to feed the wetlands with fresh water and rich alluvial soil fostering the natural habitat of the wetlands. Native plants will be given a greater chance to thrive and give refuge to the native inhabitants of this ecosystem. Even though the levee system protects the lane of shipping commerce, this special Canal will deliver to the wetlands what it needs from the Mighty Mississippi to flourish in the future.