Twain's Feast - Andrew Beahrs [95]
Then there were the jetties at the river mouth. They greatly impressed Twain, keeping the river mouth open, making navigation much safer and easier. But they also channeled the Mississippi’s mud into a massive flume, shooting it over the edge of the continental shelf into one of the deepest parts of the Gulf. Now, instead of spreading gently down the coast, all that land-building, life-giving mud was gone forever. And the Gulf Coast, it soon developed, hates a steady state: if the land isn’t building up, then it’s eroding away.
In one sense Twain was wrong: the corps has, in fact, channeled the river, tamed its lawless stream, saved shores it had sentenced. But he was deadly right that you can’t bully the Mississippi without consequence. When the engineers cut off its natural course, the river took the land it carried with it; it let the sea begin stealing the shore. Meanwhile, the century-old grid of oil-company canals—thousands of miles of them—accelerate erosion and the coast’s disappearance. Remember that the MRGO channel grew from fifty feet to two hundred in a few decades; wave action can double a canal’s width in fourteen years, making what were once nearly portages into rivers in their own right.
Now, Tidwell says, the cemeteries of some Cajun communities are under feet of water; old baseball fields are fishing grounds. He watched the GPS of one shrimping boat as it cruised easily over what should have been solid ground—the electronic map, the captain explained, was seven years out of date.
In the long term, all this means catastrophe for Louisiana’s critically important fisheries, which rely almost entirely on wetland breeding grounds and provide about a third of the nation’s catch. But for now the effects aren’t easy to see; ironically, grass that decays on sinking land causes great explosions of plankton, and fish, crab, and shrimp thrive in the kinds of edge habitats created when a solid bank of wetland breaks up. It’s much like what happened to prairie chickens, which thrived on a temporary blend of corn and grass: there were more of the birds than ever before in history, and then they were gone. If the wetlands disappear, something like that is absolutely guaranteed to happen to Louisiana’s fisheries. Sheepshead, crab, shrimp—they’ll all appear in fine condition until, seemingly at once, they vanish.
In human terms this will mean the loss of unique American coastal cultures; the evacuation of Cajuns and their neighbors might be slower than during a hurricane, but it will be no less real. And every day that the wetlands shrink is a day that New Orleans is more vulnerable to the next major storm. Every 2.7 miles of coastal wetland can absorb a foot of storm surge; where New Orleans used to have 50 miles of buffer, it now has 20 and falling. There isn’t a levee system in the world that can make up for that.
The solution, it increasingly seems, is to help the river go where it wants to go anyway. The proposed Third Delta Conveyance Channel would divert two hundred thousand cubic feet per second of muddy Mississippi River water into the Atchafalaya Basin. As it poured through the wetlands into the Gulf, it could begin halting, then reversing, the damage done by long, slow erosion. Admittedly, it’s unnerving to think of yet another cut through the wetlands, even one meant to heal. But the Atchafalaya River is the one major distributary that still carries mud and muck in something like a natural pattern; as a direct result, the Atchafalaya’s outlet is the one place that the land actually grows, by two thousand acres a year. When Mike Tidwell traveled the Atchafalaya, he became a true believer in the river’s restorative powers and the necessity for the channel; at the mouth “myriad small islands and sandbars dot the water, new ones popping up all the time, every few months,