Friday, June 18, 2010

Old River Cut-off—A Solution for the Salt Marsh?

There are two major natural factors which work to stem the advancing tide of the oil spill to the fragile eco-system which is the salt marshes of Louisiana. The first is the wind direction in the Gulf. The second is the force of the water coming down the Mississippi and its outward push from the land mass.

As the winds shifted to the northwest, they tended to push the polluted waters away from the threatened wetlands which comprise over 40% of such terrain in the US. This seasonal wind change is of course, a blessing, but with little advantage if the direction were to change. If this normal pattern continues, it buys time to implement other more concrete solutions. This, of course, underscores the necessity of immediate and unhampered action in the coastal area to avert what is shaping up to be a major disaster.

The river (Mississippi) is quite another matter. Decades ago, the US Army Corps of Engineers undertook a project to alter the flow of the Mississippi to protect downstream cities (New Orleans, Baton Rouge, etc.) and the endless miles of petrochemical industries scattered up the banks in that general vicinity. They chose a spot called Breezy Point which is on the river exactly where the LA/MS east-west border meets the river in Concordia Parish. Over a span of years they built diversion canals, spillways, dams, and relief structures to feed about 30% of the big river into the Atchafalaya (pronounced: cha-fa-lie’-yah) basin. It quickly became the life blood of the local eco-system.

The project also lessened the water levels to protect the downstream entities. New Orleans especially has long been the subject of fears from the river. Standing at the Café du Monde near Jackson Square, one has to crane the neck up, uncomfortably, to note the ocean going ship traffic’s superstructure on the river. If they are mid-river, they disappear from sight. When the hurricane hit, the levees were breeched and you know the rest of that story.

Some experts, seriously involved in the hydrology of the area, are suggesting an alteration of the dispersal of water at the Old River Cutoff. They recognize that even a slight change in the allocation of waters to increase the Mississippi flow would have a positive affect on the force of river where it meets to Gulf. They see the result as “pushing” greater amounts of water further into the sea and lessening the threat to the delicate salt marshes. This is a great idea as far as it goes but I’m certain (or at least hope) they are inhibited by two potential problems.

With an increased water level in New Orleans, the city would be subject to vulnerability if just about any minor hurricane were to strike. That season is well under weigh and the possibility is ever present. The figure of the increase would be from the current load of 70% to as high as 81%. They speculate that this could be accomplished within ten days.

The second problem is more difficult to predict. Reducing the available water to the now well established Atchafalaya River could well have an affect on the well developed eco-system in the basin. The wetlands reach scores of miles inland and could result in endless damage to bayous, swamps and extremely delicate systems over thousands of square miles. In total, the plan, while workable, does have inherent risk.

In His abiding love,

Cecil Moon

(Ed note: This piece is based on personal experience gained while living in Lafayette, Baton Rouge and Houma, Louisiana. For the finest account of the creation of the Old River Cutoff, I recommend John McPhee’s “The Control of Nature” 1989.)

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