Ecosystem restoration project proposed for Mississippi River

MEMPHIS, Tenn. — The U.S. Army Corps of Engineers is looking at a new Mississippi River restoration project, starting with a 39-mile stretch near Memphis, that could help save threatened and endangered aquatic animals.

The river’s levee system has disconnected much of the lower Mississippi’s main channel from the flood plain — an unintended consequence of the Army Corps of Engineers’ flood control and navigation projects, which have transformed the behemoth river to a more managed flow.

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Now, the Corps is proposing a sprawling ecosystem restoration project for about one-third of the lower river, starting with a 39-mile stretch near Memphis.

The Mississippi River has historically changed course as it seeks the path of least resistance to the Gulf, but the Corps said the rapid changes in the past century have disrupted the once-dynamic ecosystem. It’s diminished the connections between the river and the flood plain, while reducing habitat diversity and increasing the presence of invasive species, the agency said in a report.

Less than 25% of original forested wetlands remain in the lower Mississippi River Valley.

“Although the levee system has reduced the footprint of the historic plain, its ecological value reflects a complex mosaic of diverse aquatic and vegetative habitat,” the Corps said in its recent project proposal.

The seed for the project was planted more than two decades ago with the passage of the Water Resources Development Act of 2000, a biannual legislative package that authorizes the Corps’ activities.

A follow-up assessment in 2015 identified eight areas of highest priority for ecosystem restoration on the lower Mississippi. A few years later, the Corps launched a study near Memphis — one of the eight priority areas — to explore the possibility of a large-scale restoration project.

When the study — the largest of its kind on the lower river — ended last year, the Corps used its findings to propose a restoration project for a 39-mile stretch of river that will benefit more than 6,000 acres, spanning from the Lower Hatchie National Wildlife Refuge to the mouth of the Wolf River near Downtown Memphis.

“This is really a significant study because of the size of it,” said Jason Allmon, project manager at the Corps’ Memphis District.

The project has a few aims: increase vegetative habitats; optimize connections between the river and the flood plain; and give the public more access for recreation.

The initial construction and engineering costs to get the project off the ground total about $50 million.

The lower Mississippi River supports roughly 136 freshwater fish species, 325 migratory bird species and 50 mammal species, the Corps said. Eight of those species are federally threatened or endangered, like the pallid sturgeon and Fat Pocketbook Mussel; several other species are at risk of joining that list.

Climate change makes drought more intense, and restoring connections between the river and the flood plain is one of the ways the Corps hopes to restore habitats for threatened and endangered aquatic species.

Meander scarps are a geological feature formed by the remnants of a water channel, but because engineering activities have depleted so many of the connections between the river and the flood plain, they no longer occur naturally.

The Corps estimates that there are only 14 meander scarps remaining within the lower Mississippi River — and likely within the entire river — and three of them are in this project’s footprint. The now-rare geological feature is a “critically important habitat” for endangered species like the pallid sturgeon, whose young use them for refuge from the navigation channel.

“Because meander scarps are no longer formed through natural riverine dynamics,” the Corps said in its proposal, “the only option to preserve their benefits is to protect and restore those remaining.”

The area is also within the Mississippi Flyway, a migration route that connects central Canada to the Gulf. About 60% of all bird species in the country depend on the flyway.

“The overall goal was to really look at the whole mosaic of habitats,” said Mike Thron, lead biologist and National Environmental Policy Act coordinator for the study.

The Corps is accepting public comments on the proposed plan until March 13.

Once the Corps reviews comments, they’ll refine the plan and issue a final report to the agency’s Mississippi Valley Division office. If the final plan gets a stamp of approval from the division, it’ll be added to the Water Resources Development Act of 2024 or 2026, depending on the timing.

If Congress approves the act, the Corps will still have to secure funding. It’s a long, arduous process, but if all goes according to schedule, the Corps could start implementing the plan by 2027.

There’s a long road ahead for this project,” said Marsha Raus of the Corps’ Memphis District.

There are also seven other high priority areas that are in line for a Corps study. With one study under their belt, Raus said the Corps will find a more efficient method to tackle a wide study area.

Raus said approaching the project with all eight study areas in mind allowed them to see the mosaic of habitats on the lower river, making this proposal the first in a coordinated effort to restore aquatic habitats.

“This is the flagship study for the whole lower Mississippi,” Raus said.