The Mississippi River runs wilder near its mouth, breaking its banks in locations that provide reminders of its power while posing problems for the country’s management of the mighty waterway.

How best to deal with those problems — spanning shipping, coastal land loss and drinking water — is a growing concern that a new initiative is now set to tackle, with a focus on practical solutions.

A grant from the National Science Foundation will support the effort that will include experts in Louisiana and beyond. The Baton Rouge-based Water Institute, the University of New Orleans, Nunez Community College and the California Institute of Technology will collaborate on the project now getting off the ground.

The idea is to develop and test methods of managing the manmade and natural breaks in the river after the main levee system that keeps it in place ends in Plaquemines Parish. While it may not be readily apparent to Louisianans, managing those breaks, or crevasses, is of high importance, affecting issues ranging from saltwater intrusion to global grain exports.

The crevasses can also build land the way the river used to when it created south Louisiana thousands of years ago — a nature-based solution that could help deal with the state’s land loss crisis.

Finding solutions to what scientists refer to as “flow loss” through the crevasses could provide the state and the nation with wide-ranging benefits, particularly as rising seas inundate more coastal areas.

“It’s pretty well understood and sort of acknowledged by a lot of people that flow loss from the river in many different ways is going to be a large portion of how we deal with management of the Mississippi River going on into the future,” said Christopher Esposito, a research geoscientist with The Water Institute helping lead the project.

“And so what we’re really looking at in this is developing creative ways of improving outcomes where there is flow loss.”

An initial phase of the project has been awarded $500,000, with the potential for grants of up to $15 million over five years in the future. It has been given a convoluted name with a recognizable acronym: Coastal Resilience through Effective Versatile Adaptation and Sediment Strategies for Sea-Level Rise Engagement, or CREVASSE.

Much of it will involve evaluating ideas already out there to determine their effectiveness and the best methods of using them.

“Do you keep this particular cut open? Do you close it?” said Madeline Foster-Martinez, an engineering and environmental science expert at UNO leading the project’s management.

“But bringing this together so that nature-based solutions can actually be implemented, rather than these one-off type of things, to get something surprisingly innovative, even if it is very low-tech stuff that we’re talking about.”

Finding its level

A prominent example of a crevasse is the huge break in the river bank across from Buras, now known as Neptune Pass. Previously a small channel about 150 feet wide, it broke open dramatically with the extraordinarily high river of 2019.

Until recently, it had been regularly diverting up to 18% of the river’s flow. There are benefits to that since the pass is building land where it empties in Quarantine Bay by transporting sediment there — a naturally occurring river diversion project, research by scientist Alex Kolker and his colleagues has found.

But there are also serious downsides. Because the river slows there, sediment drops to the bottom and accumulates, causing what the shipping industry calls “shoaling,” creating a hazard for large vessels and requiring additional dredging. The pull on the river’s current in that area is also a danger.

In addition, modeling is showing that the combination of breaks in the lower river, particularly Neptune Pass, have contributed to the growing problem of saltwater intrusion up the Mississippi. When the river is low, saltwater travels up the channel from the Gulf, creating risks for drinking water supplies.

The crevasses slow the river’s flow, aiding the salt water’s advance. The deepening of the river for shipping is also a major contributor to the problem.

The Army Corps of Engineers completed work on a rock sill at Neptune Pass in October, reducing its flow to what recent measurements showed to be about 8% of the river, the Corps says, though that number will fluctuate across seasons. The sill includes a notch in the middle to allow recreational boats, water and sediment to pass through.

In response to calls from coastal advocates, the Corps may also carry out later phases of the project that would involve placing terrace-like structures in Quarantine Bay to trap sediment making it through the sill for land-building.

The Corps notes that it has long studied the crevasses, including with UNO and The Water Institute, and will continue to do so given their importance.

“The crevasses and their development have influence on navigation, dredging operations and salinity intrusion, all of which are vital USACE missions,” it said in response to questions on the new project, using the abbreviation for the Corps.

“The USACE has also investigated the role the crevasses play in land building and environmental restoration and have been actively involved in investigations of these phenomena in partnership with various entities, including those listed in the CREVASSE initiative.”

While Neptune Pass has received much of the attention when it comes to crevasses on the lower river, there are a list of others, both naturally occurring and manmade. And there will almost surely be more in the future.

They include Mardi Gras Pass downriver from Pointe a la Hache, Fort St. Philip downriver from Neptune, and West Bay, a manmade crevasse built for coastal restoration near the Mississippi’s mouth.

Just closing them all off is not considered a viable option by many scientists, both due to coastal restoration and practical implications, though some in the shipping industry disagree. The river finds its level, so shutting it off in one location means it may create another crevasse elsewhere.

‘Will cause problems’

The project will look at a wide range of options for how to manage them, both individually and as a system. That could include using more terraces, such as those planned for Neptune Pass, or other innovative ideas.

Another example involves what are known as sand dams, which would be built at the entrance to a crevasse when flow is low, then erode naturally when the river is high, with the washed-away sediment potentially building land.

The project will focus on practical, applied science approaches.

Nunez’s role, for example, will be developing a workforce to implement the ideas, led by Jaqueline Richard, chair of the school’s coastal studies. It is the first National Science Foundation award for the Chalmette-based community college.

CalTech geologist Michael Lamb will be involved in data synthesis and translation of it into practical recommendations.

The study joins several others looking at management of the lower river. They come at a key moment, nearly a century since the construction of the vast levee protection system built after the epochal Mississippi flood of 1927.

One of those studies, known as MissDelta and led by scientists from Tulane and LSU, is funded by the National Academies of Sciences, Engineering, and Medicine. Another sweeping study by the Corps is however paused due to lack of funding.

Some in the shipping and navigation industry have regularly called for the crevasses to be shut, highlighting the effects on vessels as well as drinking water. Sean Duffy, head of the Big River Coalition representing those interests, said he hopes those issues are prominently considered.

“It’s always great to study things, but in reality, the crevasses will cause problems for both navigation and civilization,” Duffy said. “We depend on the water from the river.”