Next phase of Netley-Libau Marsh Restoration Pilot project proposed

The next phase of the Netley-Libau Marsh Restoration Pilot Project is expected to start soon, with the project team hoping to implement a unique series of biodegradable baffle structures as the next step.

Red River Basin Commission Project Coordinator (Winnipeg office) joined CFAM Radio 950 Morning Show Host Chris Sumner Tuesday for the next edition of Ripple Effect to talk about update. You can listen to that full conversation below.

Netley-Libau Marsh is the largest coastal freshwater marsh in North America, and it is located at the south end of Lake Winnipeg, where the Red River empties into the lake. The marsh has undergone a major process of degradation over the last 100 years. The first phase of work was carried out in 2021 as a pilot project. This work was based on similar projects that have been carried out in coastal marshes in Louisiana. Our efforts were partially successful, but we also learned some lessons about how we might want to modify our methods in future restoration work.

"Overall, there has been a major decline in aquatic vegetation, and an increase in unvegetated muddy open water, reducing the quality of habitat for birds, mammals, fish, and amphibians," explained Adams. "To put things in perspective, between 1979 and 2001, open water increased by more than 10,000 acres. In addition to a loss in habitat, we need to remember that vegetation sequesters phosphorus, which contributes to algal blooms on Lake Winnipeg. Marsh vegetation also stores carbon, helping to mitigate the effects of climate change. But without this vegetation, these benefits are diminished."

An image from a drone showing the passive sediment being deposited

In the first phase of work carried out in 2021, sediment was dredged from the Red River and deposited in the marsh to create mudflat environments, with conditions shallow enough for plants to grow. It was the results of that work which has led the project team to its next idea.

"Our follow up monitoring last year showed that quite a bit of new vegetation growth in this part of the marsh – both within our restoration area and outside of it," noted Adams. "One thing that we have discovered is that a tremendous amount of sediment has been passively deposited in the marsh, within about 1-2 km of the site that we built the mudflats in 2021. Basically, there is an active river delta forming in this area, and the good news is that we are seeing conditions that will lead to the further deposition of sediment in this area, with newly vegetated land developing in the future. In a way, nature is healing itself, but this is a very slow process."

And what is this new idea?

"Our project team has developed a design for a series of biodegradable baffle structures, which will slow the flow of water, leading to an increased rate of sediment deposition," said Adams. "By increasing sediment deposition, and providing shelter against wave action, these structures are designed to improve conditions for plant growth. These structures are designed to remain in place permanently, decomposing over time as they become buried under new sediment, and plants grow around and overtop of them."

A diagram of baffles being proposed for next phase of the project. Supplied image.

You can also here Chris speak more at length about the project at the upcoming 13th annual North Chapter Fish Dinner Fundraiser Gala March 20th at the Access Centre (48 Holland Rd., West St. Paul, MB). Tickets are still available, and can be purchased here.