Oyster harvesters oppose diversion plan
KENNER (AP) — Louisiana oyster industry representatives have launched a new campaign to fight sediment diversions from the Mississippi River.
Save our Reefs is the slogan for the new effort that seeks to build public opposition against the proposed diversions that are a pillar of the state’s coastal restoration plan.
“Our biggest challenge right now is dealing with what the Louisiana coast will look like. Plans to change the coast are going to be the biggest part of that,” said John Tesvich, president of the Louisiana Oyster Dealers and Growers Association and chairman of the Louisiana Oyster Task Force.
The new campaign was discussed recently at the Louisiana Oyster Convention in Kenner.
The oystermen’s concern is that large-scale water diversions meant to spread sediment carried by the river’s water across dying wetlands will drastically alter the habitat of major oyster reefs.
“Oyster reefs are the most productive type of water bottom we have in our state,” Tesvich said. “The public seed grounds contain 29,000 acres of reefs. I did a rough calculation. If the average rate was five or six thick, 29,000 acres at present just raw value of cultch, you come to over $6 billion in just shell material. You can’t just replace that. They talk about we will build new reefs somewhere else. Where are you going to get that money?”
Tesvich called the state’s oyster reefs one of the most valuable assets the state has, but lamented the fact few people know about them.
This new campaign, endorsed by the state’s Oyster Task Force, will seek to change that.
“There is no consideration of this significant loss of value in the master plan,” Tesvich said.
River diversion proponents believe re-establishing something like the natural flooding process of the Mississippi River is the most feasible way of slowing the continuing erosion of land to open water.
The delta was built over thousands of years by river floods. When the Mississippi River was high, it would overtop its banks and flood the landscape, depositing sediment, nourishing the existing land and building new land.
After the river was leveed in to prevent flooding, the delta began to sink and erode, deprived of that natural process.
Diversions would open up the river in selected locations and allow water to flow into the estuaries.
State officials have argued diversions are the most cost-effective method of building land — as opposed to the labor-intensive process of dredging sediment and either hauling it or piping it to the project area.
But that argument isn’t perfect, according to a study published in March by economists from Louisiana State University and Mississippi State University.
The study, “Trajectory economics: Assessing the flow of ecosystem services from coastal restoration,” found that some sediment dredging projects are more cost-effective because they begin building land immediately, whereas diversions would take several years to produce benefit.
The claim that diversions are more effective than dredging assumes the diversions are working at full capacity, which ignores certain social and political pitfalls of diversions, Rex Caffey, director of LSU’s Center for Natural Resource Economics and Policy, said at the convention.
“Social opposition that affects the flow rate is something that should be looked at, especially in the absence of socio-economic mitigation,” he said.
Caffey said the report does not advocate for one method of marsh restoration over the other but notes some assumptions are made in blanket statements of diversion methods’ superiority.
The study is limited by lack of concrete data. Much of the information about sediment diversions are projections. The study also notes that sediment pipeline methods are limited by distance. Once the distance begins to increase, the cost-benefit analysis shifts.
That’s of particular interest to Lafourche and Terrebonne parishes, where dying wetlands are too far for diversions or any state-planned pipeline. Terrebonne Parish is pursuing the feasibility of a sediment pipeline from the Atchafalaya River.
Jerome Zeringue, executive assistant to the governor for coastal activities, said at the convention the state can’t simply “dredge our way out of this situation.”
The state plans to spend more on dredging than diversions over the next 50 years because saving the coastline will require more than one solution, he said.
“If we relied on dredging alone, just to keep up with the land loss, we would have to spend $2.4 billion per year just to keep up with what we lost,” Zeringue said.
Zeringue said models, designs and studies are still being developed for such projects. He added the concerns of oystermen would not fall on deaf ears.
“We really don’t know when it comes to oysters when it comes to effects. ... The reality is pattern abundance is not well correlated with salinity,” Zeringue said.