On Tuesday, the state’s Coastal Safety and Restoration Authority (CPRA) formally started to reconnect the Mississippi River with the Maurepas Swamp, a degraded and submerged swamp forest straight west of Lake Pontchartrain. 

Levees constructed to guard higher New Orleans had reduce off the Maurepas Swamp from the recent water provided by the Mississippi River and the Pontchartrain Basin, ravenous the swamp of vitamins, oxygen and sediment. 

Now, the CPRA is poised to reintroduce the river to the dying swamp via a brand new channel that runs from the river to the swamp, ending simply north of Interstate 10. The circulation of water coming into the swamp might be managed by a gate throughout the channel at Garyville. 

The brand new channel is outstanding as a result of it will likely be the primary giant diversion carrying river water to a submerging freshwater swamp forest. The challenge additionally showcases a brand new partnership between the U.S. Military Corps of Engineers and CPRA to jolt Maurepas again to life even because the Corps builds new River Parish levees, which is able to create additional separation between the swamp and river.

To a layperson driving down I-10, the Maurepas Swamp appears inexperienced and woody – and should not appear like it’s dying. At 220 sq. miles, it’s nonetheless thought-about one of many Gulf Coast’s largest forested wetlands. However with out recent water, the forested space of the swamp is disappearing. 

“This can be a swamp that’s been reduce off from recent water and vitamins from the Mississippi River for greater than 100 years,” stated Alisha Renfro, senior scientist on the Nationwide Wildlife Federation. “So it’s been dying for a very very long time.”

Most of the river’s levees had been constructed up through the Twenties and Thirties, after record-breaking floods prompted the passage of federal flood-control acts.  

“The swamp continues to be right here – there are nonetheless timber – they’re simply actually unhealthy,” stated Brad Miller, CPRA challenge supervisor for the river reintroduction. Tuesday’s groundbreaking marked the start of development for the freshwater diversion, which ought to be accomplished by 2028. Imagining the complicated challenge took almost 10 occasions as lengthy: its planning and design phases lasted nearly 30 years.

The devastated well being of the cypress-tupelo forest is greatest seen from the swamp’s inside. In a wholesome swamp forest, the cover can be closed, with the leaves of the timber blocking daylight from reaching the underside. However immediately the tree cowl is sparse and daylight bleeds via the cover, permitting the expansion of invasive species to outcompete native crops. The lack of native crops has led to a decline in a number of wildlife populations, together with migratory birds.

Restoring the well being of the timber would assist the remainder of the ecosystem get better. “We need to see extra bald cypress leafrollers, little caterpillars,” stated Erik Johnson, director of conservation science for Audubon Delta. 

Scientists like Johnson conclude that swampland is struggling after they see dropping numbers of caterpillars and visiting birds, as has been the case in Maurepas for many years. “We actually haven’t seen outbreaks of these caterpillars in about 20 years, and similar to that we’ve seen a 50% decline in swamp songbird specialists just like the prothonotary warbler,” he stated.

Within the Seventies and early ‘80s, the Maurepas Swamp was thought-about a haven for mallard looking. The understory beneath the tree cover nonetheless provided sufficient meals for the geese to take refuge for the winter. As tree well being declined, invasive salvinia, an aquatic weed native to South America, blanketed the water in dense mats beneath timber, choking off the native crops. 

Left with out their normal meals, the mallards had been passed by the late Nineteen Eighties, Johnson stated.

With Tuesday’s groundbreaking, the development challenge is starting with nearly no opposition, a stark distinction to the controversial and now-delayed Mid-Barataria Sediment Diversion, which has typically been touted as the biggest coastal restoration challenge within the nation by environmentalists. 

With the Barataria challenge, Governor Jeff Landry has sided with business fishermen and different critics who argue that the river reintroduction would change the ecology of the Barataria Basin, devastating individuals who fish there and Louisiana’s very tradition.

The 2 initiatives are very completely different, although they each divert river water into wetlands and play key roles in Louisiana’s Coastal Grasp Plan. 

For one, the Mid-Barataria Sediment Diversion is designed to construct land, via sediment dropped from Mississippi River water that might create as much as 26,000 acres of wetlands in Plaquemines Parish. 

The Maurepas Swamp River Reintroduction focuses solely on shifting nutrient-laden recent water into the swamp, to revitalize the well being of the cypress-tupelo forest and wetlands.

The Maurepas diversion additionally takes far much less water from the river – it’s predicted to maneuver lower than 5% of recent water getting into the Pontchartrain Basin, which quantities to lower than 0.5% of the common Mississippi River circulation. The diversion’s most circulation is 2,000 cubic toes per second and is predicted to run lower than six months yearly.

This freshwater diversion is designed to imitate seasonal spring flooding, which is crucial to cypress timber’ life cycle. The seedlings require entry to recent water and a dry interval to germinate. The timber additionally want nitrogen to develop, which is at present lacking from the swamp however can be introduced in via the river reintroduction, stated Miller.

To trace the success of the Maurepas river reintroduction, america Geological Survey (USGS) established 5 efficiency measures. If performed accurately, the brand new “conveyance channel” – a synthetic channel designed to maneuver water from one place to a different –  will mimic the flood and drought circumstances of the Mississippi River, cut back saltwater intrusion that kills cypress timber, and enhance soil elevation throughout the swamp whereas rising forest structural integrity and facilitating nutrient uptake by native crops.

The variations will doubtless be seen to scientists keeping track of Maurepas forests. “I anticipate a rise in cover cowl because the timber placed on extra leaves and wooden,” stated Gary P. Shaffer, professor of organic sciences at Southeastern Louisiana College. 

Past giving extra heft to current timber, Schaffer lastly expects to see new timber. “Pure seedling regeneration must also happen for the primary time in a long time so the forests will change into denser and their soils will change into stronger,” he stated. 

A brand new partnership in mitigation for the Military Corps’ flood safety challenge

Till immediately, Mississippi River reintroductions have centered on constructing land inside marsh wetlands, which include fewer timber, counting on grasses like easy cordgrass, marshhay cordgrass and California bulrush, alongside different herbaceous crops. The Maurepas freshwater diversion would be the first to rehabilitate almost 45,000 acres of degraded and submerged “swamp forest,” the place bald cypress, water tupelo and crimson swamp maple create native canopies.

However that’s not the one distinctive facet of the Maurepas Swamp challenge. For the primary time, CPRA has partnered with the Military Corps of Engineers to make use of the river reintroduction as mitigation for the West Shore Lake Pontchartrain (WSLP) flood safety challenge. 

To create the WSLP system, the Military Corps will construct levees, floodwalls and pumping stations to guard communities alongside the east financial institution of the Mississippi River, in St. Charles, St. John the Baptist and St. James Parishes. As soon as the initiatives are accomplished, the brand new levee will meet with the Maurepas Swamp’s new conveyance channel in Garyville. The revitalized swamp forest may also assist to additional shield the River Parishes from storm surge and flooding.

However to guard the River Parishes, WSLP will construct 18.5 miles of recent levees, additional disconnecting the Mississippi River from the Maurepas Swamp. To guard the encompassing ecosystem, the Military Corps is now required to “mitigate” the impacts of its new development via the creation of recent wetlands or the acquisition of credit in a mitigation financial institution.

“The West Shore levee is impacting numerous wetlands,” stated Miller of CPRA. “And once you affect wetlands you must mitigate for them.”

In January 2023, the Military Corps formalized a partnership with CPRA to make use of 9,000 acres of the swamp as a mitigation space for the flood safety challenge, by creating the brand new channel that reconnects the river to the swamp. 

The Military Corps will monitor the ecological progress of this swampland to make sure that the river reintroduction works as meant. Louisiana will monitor your complete 45,000-acre challenge space for at the very least 50 years, Miller stated.

Bringing the 2 initiatives collectively took numerous work, stated Renfro of the Nationwide Wildlife Federation. However now, development for each will happen concurrently, and she or he is hopeful that Maurepas Swamp will function a proof of idea for future collaborations between the Military Corps and CPRA.

By way of one challenge, it grew to become attainable to attain two objectives, Renfro stated. The Military Corps knew it wanted to make up for impacting swamp with its levee challenge. And this a part of the Maurepas Swamp occurred to suit that invoice, as a result of it was positioned within the footprint of the levee challenge and badly wanted a brand new probability at life. 

Two objectives, now meet in a single challenge. “The celebs aligned,” Renfro stated.

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