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Flood mitigation work underway for lower Chemainus River

Gravel and sediment removal one of the steps being undertaken
The Chemainus River water levels remained low into late October, but that can change very quickly with a few days of heavy rains. (Photo by Don Bodger)

People living near the lower Chemainus River will be better protected from flooding with recovery and mitigation work currently underway.

Shorter and longer-term mitigation strategies, including federally funded gravel and sediment removal, are in response to the devastating flooding experienced during last November’s atmospheric river.

At that time, the Chemainus River overflowed its banks and impacted homes, farms and businesses around the Trans-Canada Highway, as well as on the Halalt First Nation and Penelakut Tribe lands further downstream.

“I have spoken to many of the residents impacted by last November’s flooding, who will be pleased to see this and other mitigation work taking place,” said North Cowichan Mayor Rob Douglas. “I would also like to recognize Halalt First Nation Chief Thomas, who has been instrumental in securing federal funding for the sediment removal.”

Gravel and sediment removal is just one of the steps being taken to ensure a more resilient community. Other work includes: sandbag staging at two locations close to flood-prone properties within the Chemainus flood plain; a study of the flood plain, lead by the Cowichan Valley Regional District, in order to better understand the dynamics of the river; and development of an interactive 200-year flood depth map to assist and better protect floodplain property owners.

Work this week will begin on the removal of gravel and sediment build-up from a section of the lower Chemainus River downstream from the Trans-Canada Highway bridge that has significant riverbank erosion and sediment build-up. An initial phase will be to increase the capacity of the river channel by excavating sediment and gravel from a large, currently dry side channel.

Excavated gravel will be used by Halalt and Penelakut First Nations for the creation of gravel-filled ’Hesco bags,’ which can be deployed to protect property during a flood as well as stockpiling for future flood proofing.

North Cowichan has been working with Emergency Management BC and the CVRD on the development of a flood model and new 200-year floodplain mapping. The next step will be to use the flood model to examine potential mitigation strategies for this flood-prone and complex watershed. The solutions are not simple and many require considerations such as watershed scale issues, land-use, climate change and fisheries and environmental impacts.

Drivers can expect a lane closure in the northbound lane of the Trans-Canada Highway near the bridge. DriveBC will be posting details and motorists are asked to watch for signage. The area along the river will also be closed to the public during hours of operation daily between 7 a.m. and 5 p.m. while work is underway.

Project updates can be found on the BC Ministry of Environmental Protection and Sustainability website.

More information on flood preparation and to access the interactive flood map can be found at North Cowichan works closely with other levels of government and agencies on emergency preparedness and mitigation, including in floodplain areas.

People are encouraged to sign up for Cowichan Alert in order to receive notifications on a mobile device or by email about urgent or imminent events such as flooding.

Work has been going on around the Chemainus River bridge on the Trans Canada Highway to remove gravel. (Photo by Don Bodger)

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