Lower Chemainus River flood mitigation work

November 8, 2022

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

Last November, 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 land 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 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 (CVRD), in order to better understand the dynamics of the river
  • Development of an interactive 200-year flood depth map to assist floodplain property owners to better protect their property during a flood

This week, work will begin on the removal of gravel and sediment build up from one river channel. This work will address 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 Penelekut First Nations for the creation of gravel-filled ’Hesco bags,’ which can be deployed to protect property during a flood event as well as stockpiling for future flood proofing.

North Cowichan has been working with Emergency Management BC and the Cowichan Valley Regional District on the development of a flood model and the development of 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 to 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 7am and 5pm 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 www.northcowichan.ca/flooding

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

North Cowichan works closely with other levels of government and agencies on emergency preparedness and mitigation, including in floodplain areas.

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