Engineered Wetlands Filter Road Salt

Moncton's engineered and human-constructed wetlands filter road salt, protecting nearby river habitat.
Reading Time: 3 minutes

Moncton’s engineered and human-constructed wetlands filter road salt, protecting nearby river habitat. Photo by Dave Hoefler on Unsplash

Reading Time: 3 minutes

Moncton’s engineered and human-constructed wetlands filter road salt, protecting nearby river habitat.

Road salt pollution is an environmental issue that can negatively impact freshwater ecosystems worldwide. Municipalities heavily rely on salt during winter to de-ice roads and ensure safe travel. However, as snow and ice melt, excess salt runoff enters streams, rivers, and lakes, leading to elevated salt concentrations that can harm aquatic life and degrade water quality.

Elevated salt levels can disrupt the balance of aquatic ecosystems, impair the health of fish, invertebrates, and plant life, and impact drinking water supplies and agricultural lands. It also doesn’t take a lot of salt to make a freshwater system less desirable for fish that can’t survive without it.

Ducks Unlimited, a nonprofit organization dedicated to wetlands conservation, is working with the city of Moncton in New Brunswick, Canada, to reduce the amount of salt in its waterways by leveraging nature. 

See also: Biden Administration Drafts New Rules to Protect Streams and Wetlands.

The need to develop an environmental alternative stemmed after aerial video footage of Moncton’s snow dump following more than 14 feet of snow went viral. This huge snow dump site, packed with road salt and other hazardous chemicals, had citizens wondering what would happen to the toxins once the snow melted. Local officials were also concerned that runoff from snow being trucked to the Berry Mills dumpsite from different parts of the city would flow into an adjacent brook.

Because wetlands filter road salt, the city of Monton and Ducks Unlimited have been working on designing a skinny wetland that would mimic a natural one. The constructed wetland is a three-acre wetland between the Berry Mills snow dump and a local watercourse, which holds and filters the snowmelt. The wetland includes salt-resistant vegetation that can absorb most of the contaminants before the water flows into Jonathan Creek.

The runoff from the snow dump (which is filled with sand, salt, and other pollutants) is forced to flow into this new wetland feature where wetlands filter road salt. It will then exit into a more filtered state into the brook. Since the creation of this new wetland, the city has seen an increase of over 20 percent in water quality. They have also found that in addition to the decrease in road salt, there has also been a decrease in hydrocarbons, metals, and other sediments in the runoff.

This is not the first time that the city of Moncton and Ducks Unlimited have teamed up to design constructed wetlands. In 2013, after the city experienced intense and frequent storms and heavy precipitation, it needed a plan to store the excess water.

They built wetlands, which, unlike traditional stormwater retention ponds, store and filter huge amounts of water. These wetlands also capture carbon and restore local biodiversity. The Moncton Naturalized Stormwater Management Guidelines were created to formulate strategies and specifications for stormwater management practices and designs in the City of Moncton.

These guidelines establish criteria for the construction of retention ponds and offer municipal directives for implementing alternative naturalized strategies. Among these approaches is the creation of rain gardens, which feature plant species capable of thriving in conditions of excessive moisture and nutrient levels. The guidelines have become so popular that other cities and provinces use them in their plans.

With so many cities and municipalities depending on road salt during the winter months, it is concerning to think about what happens to these pollutants when the snow melts and how many ecosystems are at risk because of it. Moncton, New Brunswick’s wetland solutions are an innovative way to help reduce the impacts of salt and maintain healthy environments. Areas around the world that use salt have a lot to learn from this small Canadian town.

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