Keeping the Waters at Bay
There's no shortage of ideas on how to protect the Crescent City. But ideas are the easy part
Experts also recommend sealing off the 17th Street Canal, as well as other canals that give in-rushing water access to the heart of vulnerable neighborhoods. The drainage canals, built a century ago to move rainwater from the city to Lake Pontchartrain, used to start at the outskirts of New Orleans. But the city has grown all the way to the lakeshore, so any levee failures along the canals are dangerous. The engineers' group supports a plan to move the pumping stations to the mouth of the 17th Street, Orleans Avenue, and London Avenue canals. Shifting the pump installations, says Roth, would enable them to keep pumping during a storm and allow them to act as surge-protection dams to keep floodwater out of the canals. "The pump-station structure itself would resist surges from the lake into the canal," he says, "and that would eliminate several miles of rather fragile floodwall and levees from exposure to storm surge."
But that project would cost some $450 million and take five or more years to complete, says John Koerner, chairman of a subcommittee of Mayor Nagin's Bring New Orleans Back Commission. Koerner's group is pushing for a more immediate solution, involving "living dams"--specially constructed barges, outfitted with powerful pumps, which would be maneuvered into place and submerged at the canal mouths when storms threatened. The project would cost under $75 million and could be completed in months, Koerner says, but it's "probably ... too much to hope for." Koerner is one of many who believe that the corps will resist such novel approaches.
Koerner's group also proposes damming the mouth of the Inner Harbor Navigation Canal, to protect the Lower Ninth Ward. And it has concerns as well about an underutilized navigation channel called MR-GO, which many observers would like to see, well, go. The Mississippi River-Gulf Outlet was dredged through 76 miles of wetlands in the 1960s and is blamed for intensifying erosion there and acting as a conduit for Katrina's swell. But Koerner's subcommittee stops short of insisting that the channel be completely filled in. The channel is still used by shrimpers, offshore oil service boats, and recreational boaters, Koerner says. His subcommittee proposes constructing a type of dam that would allow boats and water to pass and have a floodgate that could close in times of danger. "We tried to serve as many constituencies as possible," says Koerner of his group's report. "If our ideas get shot down, then so be it. But let's at least get talking about something other than the same old stuff."
Nature's way. Two more groups, the Lake Pontchartrain Basin Foundation and a consortium of scientists led by oceanographer Don Boesch of the University of Maryland, have focused in particular on the region's natural defenses. For decades, the swamps, marshes, and barrier islands of the Louisiana coastline have been devastated by development. Robert Twilley, a wetlands ecologist at Louisiana State University, says that it's tough to work out exactly what protective impact an aggressive restoration effort would have, "but it's not just putting an apron of wetland there. It has to be extensive." Wetlands restoration, measured in decades and many billions of dollars, would be slow, expensive, and uncertain--and, almost everyone seems to agree, absolutely essential.