Fish Spawning Habitat Development on the Mille-Îles river

A Unique Project in Support of Sustainable Spawning Habitat

As part of the environmental compensation measures associated with the REM project, INDYCO carried out the development of a fish spawning habitat in the southern branch of the Rivière des Mille-Îles, downstream from the Grand-Moulin dam. Selected as early as 2017, prior to the start of the REM construction works, the site recognized for its strong potential as a spawning ground for walleye and lake sturgeon, also received approval from the Ministry of the Environment.

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A Large-Scale Dewatering Operation

The installation of a double cofferdam, upstream and downstream of the site, required meticulous planning and precise logistics, demonstrating our ability to operate in complex river environments.

The upstream cofferdam, installed between Île Boisée and Île Turcotte, along with the downstream cofferdam, accessible only by water, were deployed through carefully coordinated operations to secure the entire work area. The transport and installation of the downstream cofferdam by barge, guided with the assistance of a wheel loader, made it possible to overcome the challenges posed by a shallow, rocky riverbed and strong currents.

This configuration enabled the safe dewatering of a 22,000 m² section within a particularly demanding marine environment.

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Controlled Water Management

Water management proved to be a critical factor in the success of the project. Once the area was isolated, the dewatered work zone allowed for the excavation of nearly 8,000 tonnes of rock to reshape the riverbed to depths ranging from 40 cm to 1.2 m, using rounded stone suitable for fish reproduction.

A dual straw and carbon filtration system was also installed to ensure that water quality remained compliant with environmental requirements throughout the works.

This project clearly reflects INDYCO’s expertise in environmental and marine civil engineering, its consistent execution standards, and its commitment to the protection of aquatic ecosystems.

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