Dredging the Red River to Improve Water Quality

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Kevin Bunch
February 14, 2019
1923 red river

A large wetland on the south shore of Lake Winnipeg has been degraded over the decades due to human activities. But an effort to restore the Netley-Libau Marsh has reached a new stage with a pilot proposal to dredge the Red River.

Dredged materials from the river would be placed into Hardman Lake (part of the marshland) to create sediment “vegetation shelves” where native vegetation could grow. If successful, this would help restore some of the water quality functionality to the marsh, according to the Red River Basin Commission.

Over the past several decades, the Netley-Libau Marsh has lost vast swaths of emergent plants that once grew there, which provided a filter for nutrients like phosphorus that passed through the water system, said Dr. Gordon Goldsborough, water quality specialist with the University of Manitoba and member of the IJC’s International Red River Board (a separate board that’s not involved with the basin commission project). Without the plants, those nutrients are flowing into Lake Winnipeg. These vegetation shelves would allow the plants to grow back and capture these nutrients.

1923 red river
A 1923 photo shows the mouth of the Red River at Lake Winnipeg with Netley Marsh in the distance. Credit: Archives of Manitoba

The pilot project has received more than $CDN750,000 in cash and in-kind funding from sources including Environment and Climate Change Canada and its Lake Winnipeg Basin Program, the Eco Action Fund and the Federation of Canadian Municipalities.

The project was proposed by the Red River Basin Commission in 2015 to improve water quality in the basin – most notably Lake Winnipeg. It would be multi-beneficial, relieving ice-induced flooding in the region while improving the ecosystem and allowing indigenous communities to revive cultural traditions, said Steve Strang, director of the Red River Basin Commission’s office Winnipeg, Manitoba. If successful, and if the funding stream from governments is established, this could be followed by a broader effort to restore the marsh using dredged materials from the Red River.

Netley and Libau Marshes
The Netley and Libau Marshes exist on either side of the Red River as it enters Lake Winnipeg. Via IJC Maps

With the funding already received, the next step is getting the pilot project formally licensed by Manitoba and the federal government. This process can take up to eight months, Strang said. He said organizers hope to move ahead with the restoration project later in 2019, with plant monitoring through 2020. Strang added the basin commission is hoping to also receive the blessing of several nearby First Nation communities. The basin commission is looking at funding sources to extend monitoring through 2021.

According to the Red River Basin Commission, the 22,200 hectare (54,857 acre) Netley-Libau Marsh is the largest remaining coastal wetland in North America, and a major spawning, nursing and feeding area for fish from Lake Winnipeg and the Red River, as well as a vital home for birds to nest, molt, and stop during migrations. The marsh is located at the south end of Lake Winnipeg where the Red River enters the lake. Netley Marsh is on the west side of the river, with Libau Marsh on the east side.

The ecosystem has suffered over the years. Strang said that started with the creation of the Netley Cut in 1913 to reduce water levels in the marsh and allow for hay to be moved off the inner river banks. Over the years that cut has widened, allowing excess water from the Red River into the marsh, at times up to more than half of the river flow. Coupled with high water levels on Lake Winnipeg, he said the Netley-Libau Marsh has turned from a vibrant ecosystem into a “barren waste.”

Since the Red River has not been dredged in more than 20 years, silt has been building up in its course, inadvertently redirecting the stream into the marsh and effectively turning portions of it into a lake.

Strang said the proposal, to remove that silt and place it in the marsh, should raise the marsh bed enough that plants can get the sunlight they need to grow and begin restoring the marsh region to health. This would have the side effect of making the Red River more navigable for the research vessel the Namao (operated by the Lake Winnipeg Research Consortium) and private boats, Strang said, as well as allowing the ice to flow out to the lake.

With a robust community of aquatic plants pulling nutrients out of the water, the Netley-Libau Marsh would be better able to filter nutrients coming into Lake Winnipeg from the surrounding area, including the Red River. This should help reduce eutrophication (where excessive nutrients can lead to animals dying in the water) and algal blooms in the lake. Strang said by the basin commission’s estimates, restoring the marsh would reduce the amount of nutrients entering Lake Winnipeg from the Red River by 6 percent annually.

To restore the plants, the basin commission is looking at a combination of using the seeds already in the marsh bed, planting fresh seeds and root planting native cattails. The commission is reviewing siltation samples to determine what seed bank exists within the marsh and river bottom.

If the pilot proposal is successful, the Red River Basin Commission is interested in developing a joint funding proposal for the federal, provincial and local governments for annual dredging to continue supporting restoration efforts. Strang estimated it would cost around $CDN1 million; historically these costs were covered entirely by the federal government.

“It took many years to lose the marsh, and it will take many years to bring it back,” Strang said.

red river winding
The Red River still has the Netley and Libau Marshes on either side of it south of Lake Winnipeg. Credit: Gordon Goldsborough
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Kevin Bunch

Kevin Bunch is a writer-communications specialist at the IJC’s US Section office in Washington, D.C.