Officials and environmentalists lament that water once again is high in the Mississippi but sediment isn’t being diverted to marshes

After the 2011 flood pushed record amounts of silt-laden water through the Mississippi River valley, coastal activists lamented the fact that no river diversions were in place to capture some of the sediment to help rebuild Louisiana’s marshes.

Five years later, there’s another flood, and even though the state is closer to getting a large river diversion built to reroute sediment from the Mississippi River to coastal wetlands, nothing is in place yet.

“It is frustrating when you look at the satellite images of this event and the 2011 event and see the amount of sediment that the river carries,” said Chip Kline, acting executive assistant to the governor for coastal activities.

For example, with the recent opening of the Bonnet Carre Spillway to relieve pressure on river levees in New Orleans, much of the sediment is flowing into Lake Pontchartrain instead of into eroding wetlands.

In the past five years, the scientific and engineering knowledge about diversions that direct sediment from the Mississippi River into surrounding marshes has advanced greatly, but the state is still years away from construction, said John Lopez, of the Lake Pontchartrain Basin Foundation.

“Things are coming together, but it’s unfortunate it’s not faster despite many people’s effort,” Lopez said. “Basically, our capacity to take advantage of this high water is the same as 2011. Why? The wheels of progress are slow.”

There are openings in the lower river like West Bay, a cut into the western side of the levee south of Venice, where land popped up above the water line after the 2011 floods, he said.

“Where we need the sediment is farther north,” Lopez said.

Many scientists have argued that the focus for new sediment needs to be north of Venice, located in lower Plaquemines Parish. They say coastal erosion has caused so much open water in lower river areas, and it’s sinking so rapidly, that sediment from the river is best used where there is still marsh to benefit from the assistance.

The sediment does help refill borrow areas in the Mississippi River that have been mined during the past several years to build coastal wetlands, but large-scale diversions are likely years away.

The timeline is so long because the large structures require extensive engineering and design before construction, which will involve cutting through federal levees as well as crossing roads, railroads and maybe even pipelines.

Alisha Renfro, a staff scientist with the National Wildlife Federation, said one project she would have liked to see get off the ground this year was a diversion to take fresh water, but not much sediment, from the Mississippi River into the Maurepas Swamp. The project has been in the works for a long time but isn’t yet in operation. Now it appears there is some BP money from the Deepwater Horizon spill restitution that could move the project closer to construction, Renfro said.

Scientists, along with state and federal officials, also have been talking about a number of potentially quicker solutions to get more sediment into coastal wetlands, but each has run into roadblocks or never gotten off the ground.

It could be time, some coastal groups say, to start those discussions again as the state moves forward with engineering, design and permitting of larger permanent diversions.

One possibility is changing how the Davis Pond and Caernarvon freshwater diversions, which divert water from the Mississippi into coastal bays, are operated. Under the authorization for these two existing structures on the Mississippi River, they can be opened only to help manage saltwater intrusion from the Gulf of Mexico at specific levels. If the area contains too much fresh water, the diversions stay closed or are operated only minimally.

An option would be to change this plan to allow the structures to be opened in high-water situations, bringing large amounts of sediment down the river, although that could take congressional action, Lopez said.

David Muth, director of the National Wildlife Federation’s Gulf Restoration Program, agreed.

“We’re still trapped in an operational paradigm at Davis Pond and Caernarvon that is strictly based on salinities,” Muth said. “Again, here we are almost five years after the 2011 flood and we have no way to take advantage of what the river is giving us.”

Changing how the structures operate was included in a federal Louisiana Coastal Area program, but federal agencies expressed concerns about operating the structures for land building, and the state decided to focus its limited money on getting the new sediment diversions ready for construction, he said.

Another option would be to put flood gates along the two levees that guide overflow water from the Mississippi River into Lake Pontchartrain through the Bonnet Carre structure. The gates would allow sediment and fresh water to help the dying marsh on either side of the spillway. It’s something the Lake Pontchartrain Basin Foundation has been proposing for years, but the idea hasn’t gone anywhere, Lopez said.

Muth added, “It’s really sad that on either side of the guide levees on the Bonnet Carre, the wetlands are dying, and we’re just sending the sediment right past them.”

Although the state has made a lot of scientific progress on diversion and there is now the promise of steady money from the Deepwater Horizon settlement to move things forward, “it’s just frustrating because it takes a long time,” Muth said.

However, Muth said, he’s optimistic that the next time the Mississippi’s water levels run high, there will be a diversion that can take advantage of the extra sediment the river holds.

Many people share the optimism that the Deepwater Horizon settlement will move two of the state’s proposed sediment diversions closer to construction.

Louisiana will receive $6.8 billion from oil giant BP for the 2010 disaster that spilled millions of barrels of crude into the Gulf of Mexico. The state plans to use the money for coastal restoration.

“We have a strong plan with wide support and the political will,” said Kimberly Davis Reyher, executive director of the Coalition to Restore Coastal Louisiana. “We’re positioned to succeed, but how quickly can we move is the question I have.”

Follow Amy Wold on Twitter, @awold10.

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