The Coastal Crisis and Louisiana's Response

NWRC Photo

With abundant fresh water and suspended sediment, the muddy Mississippi should be a life-giving boon, delivering nutrients and land-building silt to starved coastal wetlands. In fact, each day the river carries over half a million metric tons of sediment out to sea while 48 acres of precious coastal wetlands vanish from Region Two. Ironically, although more sediment passes through this region than any other, it also suffers the highest erosion rates of the entire Louisiana coast. The region's Barataria Basin lost more than 10.5 square miles of marshland every year from 1974 to 1990. Overall, Region Two faces a loss of about 20 percent of its coastal marsh by the year 2050.

While Region Two could once boast of a wide green expanse of lush wetlands, current land-loss maps of the region now reflect an image not unlike the lacy skeleton of a fallen and decayed leaf, showing little but the faint outline of its former life.

Louisiana Office of Tourism Photo

A Controlled Response

Beginning in the early 1980s, growing numbers of Louisianans realized that the development of oil and gas infrastructure through the coastal marsh and the constraint of the river were causing serious coastal problems. The many projects created to control flooding and protect lives and property were playing a vital role, but they were also contributing to the destruction of the wetlands. In response, projects were conceived that would mimic the natural processes of river diversion through levee breaches or crevasses, and do so in a controlled fashion. By diverting a portion of the Mississippi's flow into its neighboring basins, supplies of fresh water, sediments and nutrients could be restored within the coastal areas.

In the mid-1980s, two major freshwater diversions were aggressively planned by the U.S. Army Corps of Engineers and state of Louisiana for Region Two: Caernarvon and Davis Pond. The Caernarvon Diversion, completed in 1991, directs water from the Mississippi into the Breton Sound Basin at a maximum flow of 8,000 cubic feet per second (cfs) and has already created significant improvements in the local marshland. The recently completed Davis Pond Diversion project will feed the upper part of the Barataria Basin with a maximum flow capacity of 10,650 cfs. Together, these two diversions are expected to prevent the loss of 49,000 acres of wetland over the next 50 years.

The chart on the next page describes current Breaux Act projects intended to slow the trend of wetland loss in Region Two.

Lane Lefort, U. S. Army Corps of Engineers, New Orleans District