Using the Mississippi River to rebuild Louisiana's coast: David Muth

As sources of funding from the BP oil disaster become available, the likelihood that big river sediment diversions — which are proven strategies to build land — will actually be done has some folks up in arms. Opponents of the plan, Louisiana’s 2012 Comprehensive Master Plan for a Sustainable Coast, are organizing to stop it. At this critical time, when restoration plans can finally become reality, it is important to revisit the clear science and community need that drove the master plan’s creation. It succeeded with both broad public support and unanimous passage in the Legislature.

The scientists who worked on the master plan concluded that only the sediment carried by the river can build sufficient land to begin to offset our frightening rate of land loss. Some opponents respond that “it will take too long” and “the river doesn’t carry as much sediment as it used to.” Those arguments truly leave me scratching my head. They seem the best possible arguments for getting started on big diversions immediately.

Whether or not the Mississippi River can build land is not a scientific question. The evidence is what is beneath our feet. The evidence continues to accumulate every day in the few places like the Wax Lake outlet and West Bay where we allow the river to empty into shallow water. To be able to go on living here, we just have to let it do so now in a way we can control and in places where it can do the most good. This is exactly what the master plan proposes.

The rub is all that river water introduced into our salty estuaries. Opponents argue that the change in salinities will destroy our fisheries. What they really mean is that it will move our fisheries. Estuaries are where freshwater and saltwater meet — and there will always be a place where that mixing can take place on our coast. Right now fresh and saltwater meet at the bases of our levees. It’s the salt, subsidence and sea level rise that are eating our marsh and bringing the sea to our doors. That is good for shrimp and oysters and speckled trout — while it lasts.

The problem is, it can’t last. The very forces that make estuarine fishing so good so close to home are the forces destroying our marsh. Once the marsh is gone the fisheries will collapse. The antidote is the river and its sediment — what built the marshes in the first place. It ain’t rocket science.

Some of us want to cling to the comforting illusion that we can dredge our way out of this crisis. If you read the master plan, you’ll discover that it proposes to spend $20 billion on dredging for marsh creation over the next 50 years. For that it projects we’ll end up with 200 square miles of new or maintained marsh. In the meantime, spending a fourth of that total on sediment diversions will net us 300 square miles.

So, for about $25 billion we get about 500 square miles under that scenario. But that is measured against the 1,900 square miles we’ve already lost. And it has to be measured against the additional 770 square miles that we are going to lose over the next 50 years if we do nothing. So we are still going to be down an additional 270 square miles even if we manage to raise and spend the $25 billion. What if by some miracle we could raise and spend even more on dredging?

Dredging takes the sand and heavy sediments off the bottom of the river. But there is a reason we call her the “Big Muddy.” Most of the sediment the river carries doesn’t lie on the bottom — 80 percent of it is suspended, unavailable to the dredges. That clay and fine silt is what built most of coastal Louisiana. That is what is being wasted. We would be insane to let 80 percent of the land-building sediment slip past us, unavailable to rebuild our coast.

So when we talk about not having enough time or river water destroying fisheries, what we really mean is not enough time for us here today. What we really mean is moving the fish and shrimp and oysters from where they are now easy to harvest, to somewhere else, making it more difficult for us.

Those are legitimate concerns. But for us the writing is already on the wall — our home is disappearing before our eyes, and the fisheries will go with it.

Shouldn’t we really be concerning ourselves with them? Shouldn’t we make the necessary adjustments now so that there is something for our children and our grandchildren? Will it take too long for them if we start now to build a new coast? Isn’t a fishery a little farther away better for them than no fishery at all?

David P. Muth is director of the Mississippi River Delta Restoration Program for the National Wildlife Federation.