How raising the Sumas dike could spur highway widening between Chilliwack & Abbotsford

With officials now looking to better protect Sumas Prairie before the Nooksack River floods again, the future of Highway 1 between Abbotsford and Chilliwack could be on the table.

The dike failed last November after water overtopped, then plowed straight through, a football-field-span of the vital levee. The dike’s collapse allowed Sumas Lake to reform, swamping a huge tract of farmland in the eastern part of the prairie under several metres of water.

The dike was hastily rebuilt before the second wave of storms in late November, and Highway 1 was closed to allow a tiger dam to be created at the Sumas River bridge. The temporary work held, preventing more flooding in Sumas Prairie. But the dam showed that the highway’s Sumas River crossing is a potential weak point in local flood defences.

Now that officials are looking at the dike’s future, they are also considering the future of Highway 1 through the valley, Abbotsford Mayor Henry Braun told The Current this week. Even before the flood, the dike was known to be too low to prevent a devastating flood. Now, as officials look to the future, improving the dike is the simplest way to try to keep water from the bed of what was once Sumas Lake. But because Highway 1 travels over the dike at Sumas River, raising the dike may require the highway bridge to be raised or rebuilt. And if that part of the highway gets rebuilt, the question will be how widespread construction may be.

“We had some preliminary discussions with the province about that during the flood event,” Braun said. “My understanding is they are looking at all things, including should the freeway be elevated as part of the widening project when it comes.”

The province has already declared its intention to widen the highway to Whatcom Road. As The Current reported in its first edition last spring, it hopes to do so by 2026. But it has not yet made any commitment to widen the highway further east. As a longtime advocate for highway widening, Braun says he suggested the province move sooner to widen the highway all the way to the Vedder Canal.

Braun says raising the highway all along Sumas Prairie, in tandem with a widening project, could act as a second dike to ensure water stays out of the bed of Sumas Lake.

Solving Sumas Prairie’s Nooksack problem is a complex geographical and political problem. Of many potential solutions, raising the dike is among the simplest. But even raising its level by a metre or two presents political challenges. Braun said one reason it wasn’t raised above its current height after the 1990 flood was because farmers in the western part of the prairie feared that walling floodwaters into their half of the prairie would be catastrophic for them. (They’re not wrong. When the Sumas dike breached in November and water began pouring into the eastern part of the prairie, water levels in the western part began to recede.)

A new Barrowtown?

Another potential addition to the region’s flood-fighting arsenal would be to add a new pump station near Barrowtown.

The dike splits Sumas Prairie into two segments. The western portion is higher in elevation and normally drained by Sumas River through floodgates near Barrowtown Pump Station. Water in the lower, eastern portion sits below the level of Fraser River and is emptied by Barrowtown’s four massive pumps.

LEARN MORE: The two Sumas prairies, and why the Barrowtown floodgates are so important

One reason November’s flood was so bad was because the Fraser River had risen so high that it prevented water from draining from the Sumas River via the Barrowtown floodgates. If officials had opened the floodgates, water would have flowed from the Fraser River into the western prairie. With the floodgates remaining closed, the Nooksack’s waters couldn’t drain; unable to head for the sea, they kept rising in the prairie until they breached the dike and refilled the long-drained Sumas Lake.

Braun said a second pump station to allow water to be pumped out of the Sumas River should be considered. To do so, as many as 10 pumps might be needed.

November’s flood demonstrated why that may be needed if the Nooksack floods north again. But it wouldn’t be cheap.

Barrowtown cost $27 million to build nearly 40 years ago, and just adding a second generator to the facility—as the city plans to do—will cost more than $6 million. Constructing a second pump station with multiple pumps is likely to cost far, far more.

The costs to raise dikes and highways, and to build new pump stations, are why Abbotsford started pushing in 2020 for the Americans to stop the Nooksack from overflowing in the first place. But as Whatcom County officials have noted, doing so could exacerbate flooding downstream in the United States. Among those consequences? Potentially more frequent closures of Interstate 5.

So the Canadians may choose to start work on their own flood protections, rather than wait for the Americans to decide whether to change where and how the Nooksack floods.

And Abbotsford has a lot of expensive work to do. Braun said flood damages are likely to exceed $1 billion and that federal help will be needed to keep local residents from facing a massive tax bill. Current formulas force municipalities to pay for 20% of the cost of disaster repairs. He said he has been told the province will change the formula, but what, exactly, it looks like will determine the shape of residents’ tax bills for years to come. Were the formula to remain the same, Braun said taxes in Abbotsford would need to more than double for the city to pay its share of the bill.

Urgency needed to prepare for fall, Braun says

Braun also suggested he wasn’t particularly worried by the floodway discussions by Whatcom County officials reported upon by The Current.

He said he was invited to a different meeting in which such plans were not the focus. Instead, gravel removal and dredging, a topic raised multiple times by the Whatcom County officials, was one of several different tactics being explored to mitigate and prevent future flooding.

US officials have said that last November’s storms have brought large loads of sediment downstream into the Nooksack, potentially decreasing the level of water needed to overtop its banks. Residents and local politicians there are calling for dredging the river to remove sediment that has gradually built up on the bottom of the riverbed over the last several years. They say doing so could decrease the flood risk, though it’s unclear how much of an impact it would make during peak flow events.

Braun said urgency is required on both sides of the border to get ready for next fall. In Canada, Braun believes the Sumas River and surrounding canals need to be dredged to be able to handle water when it comes. Federal regulations may slow that work. Many Fraser Valley streams are home to the endangered Salish sucker, and in-stream works such as dredging typically require federal permits in areas where established populations exist. More generally, federal regulations control the kinds of work that can happen in waterways to preserve fish habitat.

On the American side, Braun said he was pleased that US officials were exploring solutions to flood problems.

“There’ll be lots of solutions; it’s not just one size fits all. They might have to do eight or nine things,” he said.

Governments on both sides of the border have been talking about the Nooksack (and Fraser) flood threats for decades with minimal action. After the Nooksack flooded in 1990, an international task force was created to find solutions. But that task force went dormant as the disaster receded into the past, its individual members retired or moved to new jobs, and the political complexities of the solutions proved hard to overcome.

Actually getting things done that work for everyone may require six different levels of government—three on each side of the problem—all agreeing to do the same thing.

So we asked: “Whenever you talk about a government doing disaster management and having to do eight or nine things, do you really think that that’s something that can get done or will get done?”

“Yeah, that’s a concern,” Braun said. “That’s a valid concern.”