Check out the map below. See Morganza? Just north of that a bit, there’s something called the Morganza Control Structure. If (when) they open it, gabillions of gallons of Mississippi River floodwater will roll through and out into the “spillway.”
Look at that green sward that juts to the west, toward the Atchafalaya River, then turns south. Click on the link (or the map) for a clearer picture. Scroll down. You’ll see Krotz Springs on the other bank of the Atchafalaya. (Don’t worry about them. Yet). Keep scrolling.
You’ll see the Sherburne Wildlife Management Area. That’ll all be under water. Lots of it. See Butte La Rose down there, down and to the left of Sherburne? There’s a town there. That’ll all be under water. Now, what happens is all that pent up water will fill up all that green space and cover any house, camp, trailer, cow, horse or what have you as it seeks a way to the Gulf. (It’s likely that without Army Corp of Engineer involvement, the Mississippi itself would have sought this path years ago. See also: Mark Twain. See also: This really cool map of where the Mississippi has been.)
If you compare the above map with the inundation map from the Corp of Engineers, you’ll see that water basically fills up that green stretch along either side of the Atchafalaya, hemmed in on the east by 997 and on the west by, well, I’m not quite sure. Google can give you a map that will show you the cows on the farm, the Corp of Engineers apparently can’t. (SOMEBODY MASH UP AN OVERLAY!).
Remember Krotz Springs? On the west bank of the Atchafalaya? As I understand things, the little town itself (pop: 1200) should be safe as it’s ringed by a levee. But, as the spillway floods and the channels and bayous get full to overflowing, the water will start backing up. And then you’ll have water all over the damn place. Lots of it. (Check out the inundation map.) Not a whole hell of a lot of people live outside of Krotz Springs, but, just as in Butte La Rose, people DO live there. They’ve lived there a long time. Farmers. Families. Oil-field workers. School teachers. Oh, and at least one pharmacist: my dad. And his family and inlaws and such.
These aren’t people who foolishly built million-dollar homes on a barrier island in hurricane alley. The area, when it floods, doesn’t flood to the tune of 10 feet. But because the flood waters of the Mississippi will be rerouted through a river that’s already, you know, full … well, such is life near a river, I guess. And they’ll all sort of get out and go along and do what they have to do.
(Readers from Louisiana, feel free to drop in the names of other towns that could get inundated.)
UPDATE: Army Corp of Engineer video about the Morganza Spillway:
Also, look at the Corp getting all up on Facebook with FLOODFIGHT 2011!!!