Here in southeast Louisiana, we live our lives in close proximity to the power of Mother Nature and at the same time incredibly separate from it. Thanks to the efforts of the U.S. Army Corps of Engineers and local levee districts, the annual rise and fall of the Mississippi River is inconsequential to us — until we are shocked to see the wooden bays of the Bonnet Carré Spillway structure pulled to relieve pressure on the levee system. Openings are so rare and dramatic that it is almost impossible to believe that this seasonal flood stage is actually the natural way of things and not the exception.
Seasonal flooding, while terrible for people and economies that need things predictable and dry, is essential for a delta ecosystem. Geologically, these events built the land we live on, and every plant and animal in southeast Louisiana has co-evolved within this dynamic river flood cycle.
The rush of cold, fresh water into Lake Pontchartrain over the next few weeks will produce a short-term shock to the brackish environment, but in the longer term, the ecosystem will flourish. The Corps’ website explains, “Spillway openings are strongly associated with increased oyster, crab and other fisheries production in Lake Pontchartrain and Lake Borgne for several years after the flood events.”
This spring, the flood waters will stay out of our homes and businesses, but in exchange, the sediment and fresh water needed to feed our starving wetlands will stay inside the levees until it reaches the continental shelf. This fundamental contradiction between the needs of the natural system and those of the man-made system are what has led us to the loss of nearly 2,000 square miles of wetlands since 1932.
The state’s Coastal Master Plan proposes to resolve this conflict with the construction of controlled sediment diversions at strategic points along the Mississippi River. These will be designed to replicate and maximize the environmental benefits from the river’s natural flood cycles. Bonnet Carré and sediment diversions both recognize the awesome power of the Mississippi River and the human need to manage that power toward our own ends. However, unlike flood control diversions that simply see seasonal floods as a risk to be averted, we must also see them as an opportunity to reinvigorate our coastal wetlands.
chairman, Louisiana Coastal Protection and Restoration Authority