Gros Cacouna Harbour Dredging Environmental Assessment
The Gros Cacouna harbour, located in the St. Lawrence Estuary, is prone to natural sedimentation that requires periodic dredging to maintain navigational depths (harbour: 8.0 m CD; berth: 10.2 m CD) and support port operations.
Lower St. Lawrence and Gaspé Port Authority
Restoration
Cacouna, Quebec
To meet Ministry of Environment, Fight Against Climate Change, Wildlife and Parks requirements, Lasalle | NHC conducted detailed sediment transport modelling as part of an environmental impact assessment for planned dredging activities. This study focused on assessing suspended sediments concentrations (SSC) within environmentally sensitive areas including aquatic bird concentration areas, seagrass beds, as well as other sensitives areas in dredging and dumping zones. The SSCs were mapped out to present temporal and spatial variation of dilution and dispersion patterns, and their impact on water quality. The assessment also compared the impacts of hydraulic versus mechanical dredging methods to evaluate their relative environmental impacts and support the selection of appropriate dredging practices.
Supported environmentally responsible harbour maintenance by quantifying sediment dispersion impacts, protecting sensitive aquatic habitats, and informing dredging strategies that balance operational requirements with environmental stewardship using coastal modelling.
