North Yamaska River: When Hydrogeomorphology, Biology, and Engineering Unite for Stream Restoration

North Yamaska River: When Hydrogeomorphology, Biology, and Engineering Unite for Stream Restoration

At Avizo, we believe that the ecological restoration of watercourses requires an integrated approach that transcends traditional disciplinary boundaries.

With great pride, our team—composed of experts in hydrogeomorphology, biology, and engineering—was mobilized to assess the restoration potential of a reach of the North Yamaska River in the municipality of Warden, Quebec. This reach had been channelized for agricultural purposes in the 1960s.

A 360° Diagnosis

Commissioned by the MRC of La Haute-Yamaska, our multidisciplinary team conducted a comprehensive environmental characterization as part of the first phase of the Wetland and Aquatic Habitat Restoration and Creation Program (PRCMHH).

The hydrogeomorphological study, which examines watercourses as landscape-modifying agents, provided a clear diagnosis: despite the passage of several decades, the river exhibits extremely low energy and remains highly uniform. In parallel, the biological study identified 135 plant species, 12 fish species, salamanders, and snakes, as well as high-value wetland areas in zones unaffected by the channelization.

Three Approaches, One Optimal Solution

Based on this diagnosis, our team evaluated three restoration approaches:

1. Passive approach – Allowing the environment to naturally regenerate.
2. Full meander reconstruction – Restoring the historical meander pattern.
3. Functional approach – Implementing targeted interventions focused on improving ecological functions.

The third approach was selected for good reason. The passive approach would have been ineffective in this low-energy environment, while full meander reconstruction would have been excessively costly and disruptive to the already well-established biodiversity.

A Tailored and Adaptive Restoration Approach

To restore the river, our team developed a three-step strategy:

1. Selective removal of embankments to reconnect the floodplain and historical meanders.
2. Strategic integration of aquatic ledges to diversify flow patterns and create a mosaic of habitats.
3. Judicious placement of large wood structures to retain sediments, energize the watercourse locally, and enhance habitats.

This approach embodies circular economy principles—nothing goes to waste! Excavated embankments are repurposed into new benches, while trees removed when necessary are reused to construct large wood structures.

Multiple and Measurable Benefits

Mapping has revealed that the proposed interventions will enhance 52% of the existing wetlands while creating new ecological spaces.

Furthermore, hydraulic modeling conducted by our engineers confirmed the strategy’s effectiveness. These interventions will improve water flow into wetlands during frequent floods—a critical process for their ecological health—while ensuring the safety of riparian areas during major flood events.

An approach that benefits both the environment and local communities.

Our Expertise for the Future of River Restoration

This project is a perfect illustration of our expertise in river restoration. By combining our knowledge and skills, we design effective and sustainable solutions tailored to local specificities.

RARE Project (Recherche et approches pour une restauration éclairée)

We are thrilled to announce that the North Yamaska River restoration project has been selected for ongoing monitoring under the societal axis of the RARE Project. This initiative aims to develop revegetation strategies for degraded wetlands while examining the key factors that determine restoration project success.

Partners

Ministry of the Environment, the Fight Against Climate Change, Wildlife and Parks, through the PRCMHH, and the MRC of La Haute-Yamaska.