Published:November 19, 2021
Indeed, a consultant’s report found that most of the sample of dikes surveyed in the Lower Mainland were vulnerable to failure.
The failures of a 100-metre section and a second, smaller section at Cole Road of the Sumas Lake reclamation dike in Abbotsford have exacerbated the flooding in the community of 150,000 in the Fraser Valley.
A temporary replacement is being built in place of the 100-metre failure in order to prevent the flow of more water into Sumas Prairie, an area of farms with a population of about 3,000. Sumas Lake was drained in the 1920s to create much of the farmland.
John Clague, a professor emeritus of earth sciences at Simon Fraser University, and a longtime supporter of prompt action on climate change, said a legitimate question is why such information has not been acted on.
“What’s the point of collecting it, if you are not going to do anything?” asked Clague.
The 2015 study by government of B.C. consultants assessed a sample of 75 Lower Mainland dikes and found that 71 per cent were vulnerable to failure by overtopping, where floodwaters go over top of the dike and wash it away, during either a major Fraser River or coastal flood.
The report rated the highest elevation of the key Sumas Lake reclamation dike in Abbotsford as “unacceptable,” the lowest possible in the survey. “Overtopping is expected during Nooksack River overflow,” said the report.
And that is exactly what happened this week.
The report noted the height of the dike at the Cole Road crossing was 60 centimetres below the design for a major flood. The dike collapsed at that spot this week.
But action, which comes at a high dollar cost, has been slow.
In a briefing Friday, Public Safety Minister Mike Farnworth said there has been continued maintenance and dike improvement projects.
“But, you know, events like this show very clearly that climate change is going to impact us in ways that it never did in the past,” said Farnworth. “That means that, yes, the province and the federal government are going to be paying and investing in the years to come in our diking system,” he said.
Following a 1990 overflow of the Nooksack, which caused extensive flooding in Abbotsford, an international group was created to assess risks and come up with a mitigation plan. The Nooksack River International Task Force was active until 2012, then went dormant for eight years before being revived in May 2020.
Originally it contained members of B.C., federal and Abbotsford governments, as well as federal, state, county and community government representatives from across the border.
The new iteration of the task force has the same types of members, but fewer participants from the U.S.
As early as 2003, the task force had warned that a one-in-200-year flood would put Highway 1 underwater for nine days and flood 1,160 primarily farm properties with a conservative estimate of $130-million damage.
An updated 2020 consultant’s report carried out for the City of Abbotsford found that damage from a major flood could be as high as $960 million.
Early estimates this week for dike repairs and flood compensation in Abbotsford alone top $1 billion.
Dike fixes outlined in the 2020 report could cost anywhere from $29 million to $339 million, but no action has been taken.
When the report was delivered, Abbotsford city councillors said finding a solution to flooding risk and getting funding from higher levels of government is an issue that must not get dropped or shelved.
Last December, Mayor Henry Braun said risks linked to inadequate dikes and overflow problems from the Nooksack River were already known. He noted the amount of money that’s required to mitigate risks is not easy for senior levels of government to grapple with, including, likely, in the U.S.
“We need to keep the pressure on,” said Braun.
Abbotsford councillor Brenda Falk said at the time it’s easy to forget flooding risks until you have a flood.
“So this is a very big eye-opener,” she said, speaking of the report. “I’m sure for some who don’t even realize that we have any such danger here in our region, and the work is very significant.”
The 2020 report noted that options considered to mitigate flooding from overflow of the Nooksack River into the Sumas Prairie area had included raising the dikes.
Postmedia has learned that the province has carried out an updated risk assessment of the more than 200 regulated dikes in B.C., with a total length exceeding 1,100 kilometres. It was completed in February 2021.
However, officials say that due to the size and scope of producing the provincewide dike review, the data has taken some time to compile and visualize.
Officials said the ministry is in the process of completing quality control, and intends on providing the findings through a “secured dike information portal” to local governments and other diking authorities when it’s completed next month.