The CVRD is seeking funds for a new plan for the Cowichan River dike system. (File photo)

The CVRD is seeking funds for a new plan for the Cowichan River dike system. (File photo)

CVRD seeks grant for plan after new flood maps show potential problem areas

Maps adjusted for a climate change and sea-level rise scenario in the year 2100

More and better dikes, as well as higher bridges and roads, will likely be needed in the floodplains of the Cowichan and Koksilah rivers in the future as climate change intensifies, according to a report that was presented to the board of the Cowichan Valley Regional District.

Based on the information and updated flood maps provided by Northwest Hydraulic Consultants, the CVRD will apply for a federal grant on behalf of the district and its partners of up to $200,000 to support the development of an asset management plan for the Cowichan River dike system.

The CVRD’s board made the decision to apply for the funding from the Canadian Municipalities Municipal Management Program at its meeting on March 10.


The floodplain maps presented by the engineering company represent a designated 200-year flood adjusted for a climate change and sea-level rise scenario in the year 2100.

The Northwest Hydraulic Consultants’ report said the major flooding that took place last year on Feb. 1 in the Valley was a 30-year event and caused significant erosion and sedimentation along the north and south branch of the Cowichan River.

The report said it would be useful to re-survey the river to assess the risk of future channel instability in response to the flooding incident so that measures for restoring the channel could also be designed.


“The climate-change scenario represented in this study is more severe than in previous investigations, with the designated river discharges being up to 30 per cent higher than in previous flood mapping studies,” the report said.

“A concept for mitigating flooding on the low-lying land between the south branch of the Cowichan River and north side of the Koksilah River was developed. This will require constructing a perimeter dike starting on the north side of the Koksilah River at Highway 1, extending downstream along the north side of the Koksilah River and eventually turning northwards along the south side of the Cowichan River and then tying in to the end of the new Hatchery Dike.”

The report said that model results indicated that, in order for a south Cowichan-Koksilah dike to be fully effective, a section of Highway 1 will need to be raised, or blocked by a temporary flood barrier.

Planning future upgrades to the existing dikes in both river systems in response to climate change was also among the recommendations in the report.


“It is expected that the peak discharges will continue to increase over the century; however, the rate of increase is presently only poorly understood and the assumed climate change scenario adopted in the study will need to be continuously reviewed and revised in light of new information,” the report said.

“Dike raising will be required in sections of the Cowichan River upstream of the Joint Utility Board’s sewage treatment plant.”

The report also recommends planning for future upgrades to roads and bridges in the floodplains as virtually all bridges on the Cowichan River, Somenos Creek and Holmes Creek have inadequate clearance under present 200-year flood conditions, let alone under future climate change.

“Assessing and designing channel maintenance measures such as sediment removals and log jam removals to ensure the stability of the rivers can also be maintained,” the report said.

The CVRD’s board also decided at its meeting on March 10 that the district send the updated floodplain mapping of the Cowichan and Koksilah Rivers to the Ministry of Transportation and Infrastructure, and request that any future work in the area be coordinated with the Cowichan Flood Management Working Group.

Like us on Facebook and follow us on Twitter

Climate change

Get local stories you won't find anywhere else right to your inbox.
Sign up here

Just Posted

The old Stanley Gordon school in Lake Cowichan. (Lexi Bainas/Gazette file)
Editorial: Old school properties represent potential for our areas

There are opportunities, often sitting right in the middle of our small communities.

Sweet gum trees like this one in City Square will be replaced over the next three years. (Kevin Rothbauer/Citizen)
Duncan plans big tree replacement project for downtown

Sweet gums in City Square and along Station Street will go over the next three years

Cowichan Valley Capitals defenceman Logan Rands pokes the puck away from Alberni Valley Bulldogs forward Talon Duff. (Elena Rardon/Black Press Media)
Offence sags as Cowichan Capitals reach midway mark

Caps score one goal in three games as pod season continues

BCYP Minister for the Southern Interior, Aislinn Dressler of Fernie said the Youth Parliament being virtual was a great way to learn about how the BC Parliament was operating. (Photo contributed by Aislinn Dressler)
Applications open for Islands Youth Parliament

Applications must be received by April 23

A large crowd protested against COVID-19 measures at Sunset Beach in Vancouver on Tuesday, April 20, 2021. (Snapchat)
VIDEO: Large, police-patrolled crowds gather at Vancouver beach for COVID protests

Vancouver police said they patrolled the area and monitored all gatherings

A teacher-librarian in Nanaimo was fired in 2019 for checking out an age-inappropriate graphic novel to a student. The discipline agreement was published Wednesday, April 21. (News Bulletin file photo)
Nanaimo teacher-librarian fired for checking out too-graphic graphic novel to student

Teacher had been previously disciplined and suspended on two occasions

Aria Pendak Jefferson cuddles ChiChi, the family cat that ran away two years ago in Ucluelet. The feline was missing until Courtney Johnson and Barry Edge discovered her in the parking lot of the Canadian Princess earlier this month. Aria and her parents were reunited with ChiChi in a parking lot in Port Alberni. (SUSAN QUINN/ Alberni Valley News)
An Island girl’s wish is answered as her cat came back

Courtenay family reunited with cat that went missing in Ucluelet in 2019

Cannabis bought in British Columbia (Ashley Wadhwani/Black Press Media)
Is it time to start thinking about greener ways to package cannabis?

Packaging suppliers are still figuring eco-friendly and affordable packaging options that fit the mandates of Cannabis Regulations

Vancouver Island Connector and Tofino Bus is putting a 41-passenger electric bus through its paces in a three-month trial run between Nanaimo and Victoria. (Photo submitted)
Electric bus on trial run serving Victoria-to-Nanaimo route

Vancouver Island Connector and Tofino Bus trying out 41-seat electric coach for three months

The Coastal Fire Centre is looking ahead to the wildfire season on Vancouver Island. (Phil McLachlan – Western News)
Coastal Fire Centre looking ahead at wildfire season on Vancouver Island

‘We’re asking people in the spring to be very careful’

Chum Salmon fry being examined with multiple motile and attached sea lice on Vargas Island. (Cedar Coast Field Station photo)
Study: Tofino fish farm sea lice infestations add fuel to push to remove open pens

Ahousaht First Nation asking for higher standards than what DFO requires

FILE – The Instagram app is shown on an iPhone in Toronto on Monday, March 19, 2018. THE CANADIAN PRESS/Graeme Roy
Judge acquits B.C. teen boy ‘set up’ on sex assault charge based on Instagram messages

The girl and her friends did not have ‘good intentions’ towards the accused, judge says

Kai Palkeinen recently helped a car stuck on the riverbed near the Big Eddy Bridge. While the car could not be saved, some of the driver’s belongings were. It’s common for vehicles to get stuck in the area due to significantly changing river levels from Revelstoke Dam. (Photo by Kai Palkeinen)
“I just sank a car’: Revelstoke resident wants Columbia River better protected

Although it’s not permitted, the riverbed near the city is popular for off roading

Most Read