Mighty Mississippi River threatens land loss

By Luke Nozicka

Louisiana is losing a football field worth of wetland each hour.

Based on a U.S. Geological survey, coastal Louisiana has lost 16.5 square miles a year for the past 25 years, and one professor was chosen to evaluate and recommend scientific advice to save them.

Loretta Battaglia, an associate professor of plant biology, was appointed to the Water Institute of the Gulf ’s River Diversion Expert Advisory Panel.

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The panel reviews and evaluates plans for freshwater and sediment diversions designed to build new land and restore wetland habitat in coastal Louisiana.

“Louisiana contains our nation’s largest wetland,” she said. “It’s a beautiful, special place that we are loosing rapidly.”

The panel will advise a project being partially funded with $5 billion from the BP Oil spill settlement. Other federal and state money is being distributed to the project.

Battaglia said the overall cost of the 50-year project is $50 billion, but the organization does not yet have all the money. Various parts of the project will carry out over time.

The expert team then provides scientific advice about diversions and future planning to policy makers and those implementing the project on the ground.

“The Mississippi River has migrated around a lot in her floodplain and particularly where the river meets the sea,” Battaglia said. “The river naturally moved around, seeking the closest route to the sea, and abandoning previously occupied lobes. Under natural conditions, this building and abandonment of lobes occurs on a several thousand-year cycle.”

Lobes are former deltas that were built and when abandoned by the river, and no longer replenish sediment.

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Tom Minello, branch chief of fishery ecology at National Oceanic Atmospheric Administration Fisheries said the purpose of the panel is to provide insight to potential impacts of these diversions.

“In addition to what the stated objectives are, there’s a potential for a variety of other impacts that maybe need some looking into,” Minello said.

There are 12 experts on the panel, including ecologists, sociologists, marine biologists and fishery and policy concerned specialists.

Battaglia said the river’s current course is held in place by a system of levees and other water control structures that largely prohibit overbank flooding.

This has reduced sediment inputs to the floodplain and essentially stopped new land building.

“Upstream in the watershed along the Missouri River, for example, there are a lot of dams that trap sediment,” she said. “So there’s a shortage of sediment that is being moved down the river. The river itself is sediment starved.”

Without sediment, the chances of new land building in the area are slim to none and the whole coast is shifting downward.

“So not only is average sea level rising globally, but in coastal Louisiana the relative sea level rise is much more rapid because there’s not as much sediment,” Battaglia said.

Another factor of the coastal land loss is oil and gas exploration. Canals were dug into the coastal marshes, which enables salt water to intrude, Battaglia said. She said all of these things add up to dramatic land losses in the area.

“So, you have salt water coming into the system, conversion to open water, and ultimately loss of all this habitat,” she said. “So one of the approaches that has been suggested, and there have been a couple of early projects that have done this, is that we need to open some holes essentially through the levees of the Mississippi River and allow that fresh water to permeate back into the floodplain.”

Battaglia said this is already happening in Louisiana in Wax Lake and Caernarvon, an unincorporated area in St. Bernard Parish.

These diversions offset saltwater intrusion by pushing it back toward the ocean. She said the issue with this is no sediment is being pushed into the area.

“These other diversions, the newer ones are being planned with the idea that not only will we pump freshwater into the area but also there will be sediment,” she said. “If you can get the flow fast enough it can carry sediment into these receiving bases. That’s the idea, to initiate land building and offset ongoing land loss.”

Battaglia said some members of the public, including commercial fishermen of the area, are concerned because the nutrient rich water from the river may alter habitats for many plants and animal species, some of which are economically valuable.

The local fisherman concerns are just a few of the many matters discussed during panel meetings.

Milleno said the meetings are public, so anyone may acquire the recommendations.

“I assume that there will be some involvement of the public and the people of the state of Louisiana, and deciding on how this diversion issue will proceed,” he said.

The panel had their inaugural meeting Jan. 8 and 9 in Baton Rouge, La. At the first meeting, they identified and discussed the uncertainties of the project.

Panel members are appointed for three years, during which they meet three to four times each year.

“Our charge is being an advisory panel,” Battaglia said, “Meaning we don’t make any decisions. All we can do is meet with the people who are involved in the planning and the implementation of the diversion. They present their plans to us and we ask a lot of questions, and we go into our panel meeting and discuss it.”

She said there are 12 freshwater diversions in various stages of planning, implementation and operation.

Minello said there are several specifications to be appointed this position, and not living in Louisiana was one.

Laurie Achenbach, interim dean of the College of Science, said the panel is a handful of experts around the country.

“This is a real honor for Loretta, and for the institution as a whole, to be part of a process that could result in policies for water use on the Mississippi,” Achenbach said.

Battaglia said this is one of the biggest hydrologic restoration projects in the world.

Luke Nozicka can be reached at [email protected], on Twitter @LukeNozicka, or 536-3311 ext. 268.

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