Turning the Tide

The Great Wall would supposedly protect wetlands and the people who live on them. But levees by themselves rarely protect anything, and they destroy wetlands by cutting them off from freshwater and sediments.

The environmental community has learned some lessons, too, none more important than the fact that levees are necessary. “You can’t go back to when there were no levees and the river just flooded every year,” explains the National Wildlife Federation’s regional director, Susan Kaderka. “But in a controlled way, we need to reconnect the river with the delta.”

That’s what the multiple lines of defense strategy—as set forth in a 178-page report produced by the Lake Pontchartrain Basin Foundation and the Coalition to Restore Coastal Louisiana—is all about. Levees are like scalpel cuts; depending on how and where they’re made, they can be life ending or life saving. The report recommends a cheaper, shorter alternative to the Great Wall in the form of a more northerly levee route (“alignment”) that encloses far fewer wetlands and uses wetlands to the south for a buffer. When storm surge hits naturally vegetated wetlands, it slows and settles. Every 2.7 miles of marsh grass between a point of land and the sea reduces flood level by one foot, estimates the Corps.

“No one argues that these people shouldn’t have protection from hurricane surge,” says Audubon’s Kemp, one of the report’s authors and the former LSU professor and coastal-restoration expert who did surge modeling for the state and helped produce its forensic study on the flooding of New Orleans. “But our experience with Hurricane Katrina east of New Orleans in the Mr. Go funnel was that enclosing wetlands with levees exposed to waves is a recipe for disaster. First, the coastal wetlands die, and second, the levees fail. We need to put the levee behind the wetlands, not out in front.”

John Lopez—the report’s lead author and director of the Lake Pontchartrain Basin Foundation’s coastal sustainability program—has a personal as well as a professional motive for restoring wetlands. Katrina took his house on Lake Pontchartrain, leaving not a splinter. There’s no side of any wetlands or levee issue he doesn’t know. For 20 years he worked as a geologist for Amoco. Then in 2001, while continuing his doctoral work at the University of New Orleans documenting environmental impacts from such events as oil spills and hurricanes, he signed on with the Corps. In 2005, 16 years of volunteer work for the foundation morphed into a full-time job.

From five feet below the level of Lake Pontchartrain’s surface, Lopez and I surveyed the urban sprawl along the south shore. We weren’t wading; it was just that all the development there had subsided along with the sediment-starved, desiccated, leveed delta on which it squats. Katrina had kicked up nine-foot waves on the 25-by-40-mile lake, damaging the levees. Now Lopez’s foundation is working to buffer them with the kind of wetlands that used to fringe the shore. The plan is to build a breakwater several hundred feet out into the lake, then pump in sediment. With the new marsh will come an invasion of shorebirds, wading birds, and waterfowl.

We left Lake Pontchartrain and drove west on Route 10 to the LaBranche wetlands, between the St. Charles Parish levee and Lake Pontchartrain. Three hundred acres of marsh had been built here by pumping sediments from the lake. Lopez called it a “good example of what needs to be done on a large scale.” Some of the hunting camps to our left had survived the storms, and the landowners are requesting an additional sediment-pumping project.

Another good example is the Davis Pond diversion at the top of the estuary and about 78 miles from the Gulf, though its purpose is more to prevent saltwater intrusion than build land. “It’s pointless to introduce sediment here because it would just choke up existing wetlands and not get down to where we need it,” said Lopez as we stood on top of the levee, perusing the enormous, $200 million diversion structure. Out on the brown Mississippi a freighter eased downstream, a barge towed by a tugboat plowed upstream, and below us two black-bellied whistling-ducks preened on wet rocks.

The LaBranche wetlands and the Davis Pond diversion are just two of about 70 larger coastal wetlands projects that, together, have restored 100 square miles of wetlands in the past 17 years. That sounds like a lot until you consider that the state has lost 2,100 square miles since 1932. “It’s a good program but not on the right scale,” said Lopez. “To really make a difference you need major river diversions. The multiple lines of defense strategy is a minimalist approach—just things you have to do in the short term. We propose building another 150 square miles of marsh over the next 10 years by pumping sediment.”

Lopez and his allies will do well to get funding for even this minor work. Maybe some small-scale version of the Great Wall will eventually get built. But anyone who believes the state can wangle $11 billion in federal pork for an old-style Corps mega-project is dreaming. There are, however, lots of dreamers in Terrebonne Parish. And their all but hopeless fight for the Great Wall perfectly illustrates the clash between old and new thinking.