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Plan in place to create two new deltas
By Todd Masson
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Up until the late 1960s, the Louisiana scientific community was in agreement that the marshes of our state were stable, and that significant erosion was not possible.

This condition of coastal equilibrium was taught in college classrooms and printed in textbooks.

But in 1968, a young genius named Sherwood “Woody” Gagliano dicovered that the state of Louisiana was losing a whopping 16.5 square miles of marshland a year. The numbers were clear and indisputable.

Ever since, Gagliano, a lifelong Louisiana resident who holds three degrees, including a doctorate in geomorphology, from LSU, has been on a quest to develop projects to save the Bayou State’s fragile coastline.

The biggest and most-important of his creations is the Third Delta Conveyance Channel.

Gagliano and his associate, Johannes van Beek, first formally introduced the idea in a report they wrote in 1994 for the governor’s coastal-erosion committee, and in 1998, the proposed channel was made the key element of Coast 2050.

“I love this project,” Gagliano said. “It won’t solve all our problems, but it’s the cornerstone of the plan to solve a whole lot of our problems. It has more environmental benefits than all the other projects combined.”

As proposed, the Third Delta Conveyance Channel would divert 200,000 cubic feet per second of river water through a break in the river levee just downstream of Donaldsonville.

Thirty miles downstream from there, around Lake Boeuf, the channel would split in two, with the water continuing down man-made channels on either side of Bayou Lafourche.

One channel would empty into the Barataria Estuary, the other into the Terrebonne Estuary.

Because of the current shallow condition of the estuaries, accretion of sediments would begin almost immediately, and eventually new deltas, with the vibrant flora and awe-inspiring fauna that go along with them, would form in the two estuaries hit hardest by coastal erosion and subsidence.

The channels themselves would be dug very shallow — about 12 feet deep — to allow the rushing water to maintain its forward speed and hold its sediment. Once the water encountered the broad estuary, it would slow down and, as a result, drop its sediment load.

The fast-moving water would also collect sediment from the bottom of the channels, and transfer it into the estuaries. Over time, this would make the channels deeper and allow more water to be diverted.

“Those channels, with sufficient flow to carry silt — not clay or simply fresh water — will build land rapidly, particularly since we’re letting the channels self-scour. We’d see almost immediate stabilization (of the marshes),” Gagliano said.

It may sound too good to be true, but it’s not. The problem is that it’s too good to be cheap.

The entire Coast 2050 proposal would cost $14 billion to implement, and a full $2 billion of that would go toward the Third Delta Conveyance Channel.

The feasibility of the Coast 2050 plan is currently being studied as part of the Louisiana Coastal Area Comprehensive Study. If it is deemed feasible, Coast 2050 could, in 2004, become part of the Water Resources Development Act, which is a biennial bill through which Congress funds water-related projects.

But even if Congress votes to approve funding for the Third Delta Conveyance Channel, the marshes won’t benefit from the sediment-rich water it promises until at least 2014.

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“We conceived of building a control structure plus a small pilot channel with guide levees, and the channel would be dug only deep enough to create the guide levees. Then the structure could be opened incrementally so that the channel could scour. Doing it this way, we could get it fully operational in less than 20 years — maybe 10 or 15 years, but certainly not less than 10,” Gagliano said.

One of the drawbacks of the plan is that it will greatly alter the hydrology of both the Terrebonne and Baratariaestuaries, and as the Caernarvon diversion has demonstrated, many Louisianians don’t like the inconveniences of coastal-restoration projects.

But the way Gagliano views it, we don’t have any choice.

“We’re really fighting a tremendous battle,” he said. “The timelines are very short. I’m deeply concerned with the lack of a sense of emergency. There’s no sense of urgency. Unfortunately, it may take one big storm to get the public’s attention.”

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