Geological impact of Morganza spillway opening

Last Update: 5/09 11:07 pm

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Video 1 of 1 All Video Geological impact of Morganza spillway opening Crowds gather near the Bonnet Carre Spillway as the Corps begins removing pins to ease pressure on Mississippi River levees. (Evan Anderson, FOX 8 News) Fishing in the river isn’t anything new for Warren Smith. What is new is the height of the river he’s fishing in. “Normally, we’d be by those trees right there. In another two days, water is going to be to the levee and we aren’t going to be able to come right here,” says Smith. To ease pressure on the New Orleans levee system, the Corps partially opened the Bonnet Carre Spillway on Monday.  Without knowing if that will be enough, the Corps has asked for permission to open the Morganza Spillway north of Baton Rouge. The last time the Morganza was open was in 1973. “Which was another really big flood. We really saw the levee system that we have tested. In fact, the old river control structure was almost lost.” Through the years, Tulane Environmental Law expert Mark Davis, says the levees and structures were rebuilt much stronger. “They haven’t really been tested in the same way since 1973. I think people should have confidence but as we saw in Katrina, no one should be overly confident,” says Davis. 40 years ago, there was serious flooding and it’s expected this time around to flood again, if not more than 1973. The people of Morgan City will no doubt be affected. “You really only see it taking on water once a generation, and of course, people farm, hunt, they trap and life goes on, but it goes on with knowledge that when the big one comes, you are going to be carrying the burden for a lot of other places,” says Davis. Besides flooding, the oyster industry is expected to take a big hit. It will also alter the geology of the Atchafalaya swamps and the bays toward the bottom of the river.  In 1973, sediment carried through the spillway created a delta that still exists on satellite images today. “It will be fascinating to see how much sediment is deposited both within the spillway and base of it. Part of that is a land building benefit and the other part of it is if you start building too much sediment in the Atchafalaya system you start taking away the future capacity in that system to deliver a project flood,” says Davis. Davis says it’s about managing the flood. Creating new land at the end of the Atchafalaya may be the only benefit from the opening up a spillway that has the potential to negatively affect so many.