In late fall, amidst the Lake Saint-François National Wildlife Area, the Digue-aux-Aigrettes marsh appears quiet on the surface. But at the bottom of the marsh it’s a different story. Turtles, reptiles and amphibians of an impressive diversity have settled there to hibernate. How do you start a construction site in the area without disturbing them during this long sleep? DUC and Environment and Climate Change Canada (ECCC) took up the challenge.
A Unique Environment
On the southern shore of Lake Saint-François, in southwestern Quebec, at the borders of the United States and Ontario, lies the Lake Saint-François National Wildlife Area, a jewel of biodiversity recognized as an internationally significant wetland under the Ramsar Convention. The Digue-aux-Aigrettes marsh lies at the core of the area, in an exceptionally rich environment.
In 2018, the dike and the water level control system of this marsh were nearing the end of their lifecycle. ECCC, as the owner of the site, mandated DUC, their longtime partner, to restore the wetland. This $1.5‑million project was funded by DUC, ECCC and partners in the North American Waterfowl Management Plan. DUC found itself on familiar ground, having built the original facilities 35 years earlier.
But it was a huge challenge. Why? Because the area is home to plants and animals at risk. “The presence of protected species means the project has to meet very strict specifications”, says Mark Gloutney, DUC’s director of regional operations for Eastern Canada and B.C. “We had to demonstrate that we could protect them. It took several months to come up with a solution.”
Schedule, construction methods, budget… “Everything was calculated to minimize the environmental and wildlife impacts”, says Charles Clavet, a protected-area planning specialist with ECCC.
The presence of protected species means the project has to meet very strict specifications. We had to demonstrate that we could protect them. It took several months to come up with a solution.
Please Do Not Disturb!
The best time to act in a wetland with machinery is winter. “There is then a better bearing capacity for the equipment, which avoids damaging the environment. The risks of harming wildlife are the lowest; bird migration is over while amphibians and reptiles are immobile, captive in the aquatic environment,” explains Clavet.
The glitch: it is also at this time that some animal species, including turtles, settle deep in the marsh, near the shore, for the cold season. “Their heart beats at a slower rate, barely two or three beats per minute”, says Sylvain Giguère, a biologist specializing in the recovery of species at risk at ECCC. “You can’t run away from danger”.
So, we had to plan ahead. “In the late summer of 2019, exclusion fences were set up to prevent turtles from using work areas to hibernate”, says Gloutney. This creative solution allowed crews to work without interfering with the turtles.
A Long-Term Vision
The opportunity was ideal to provide the site with modern, more sustainable facilities. The addition of a geomembrane in the dike controls the percolation phenomenon and increases the lifespan. The water control structure is made of high-density plastic.
But there is more. The teams have created favourable locations for turtle spawning, safer than the roadside areas where they have the unfortunate tendency to go, risking their lives. “Knowing that predators are fond of their eggs, we understand that very few (turtles) will become adults and that the health of these populations depends on females’ longevity. Road mortality is particularly damaging to them,” emphasizes Giguère. “So the project has been an asset for this species.”
Long-Term Partners
DUC and ECCC have a 40-year history of joining forces and share a common vision for wetland conservation. “The complicity between our teams has made things much simpler, despite the complexity of the project”, says Charles Clavet. “We had the same understanding of the issues and a common goal of working without compromising the environment to generate a final product matching the value of this unusual site for wildlife and visitors.”
The Digue-aux-Aigrettes Marsh: Full of life
Many ornithologists and nature lovers know the Digue-aux-Aigrettes trail. They converge there during waterfowl and songbird migrations and throughout the summer to observe life in all its forms.
The DUC marsh is a fine example of manmade management serving biodiversity. Along 3.7 kilometres of trails with footbridges and lookouts, walkers can observe an abundance of plant species in various shapes and colours and get to know the marsh inhabitants, like:
- Ducks, including the redhead, the wood duck and many species of dabbling ducks;
- Herons and other ardeids, such as the great blue heron, the great egret, the black-crowned night-heron, green heron, least bittern, etc.;
- Turtles, amphibians and reptiles.
This outstanding ecosystem is located in the heart of the Lake Saint-François National Wildlife Area. Created by the Government of Canada in 1978 to preserve a unique set of wetlands, it is home to 546 plant species and 287 animal species, 15 of which are protected under the Species at Risk Act.
National Wildlife Areas (NWAs)
DUC is upgrading dikes and water control structures and will jointly manage wetlands to ensure quality habitat for migratory birds including waterfowl, at-risk species, and other wildlife at other NWAs across the country.
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