Could re-flooding the Sumas Prairie help buttress Abbotsford against climate change?

You’ve heard about fighting fire with fire, but what about fighting water with water?

It’s an idea at the heart of a proposal in a new UBC study, which suggests the best way to prevent flooding in a key part of the Fraser Valley might be to flood it intentionally.

The research, published in the journal Frontiers of Conservation Science, looks at the idea of restoring Sumas Lake in Abbotsford.

The B.C. government drained the lake in the 1920s to make room for farmland, displacing the Sumas First Nation and its members.

4:41 Improving flood resilience in Abbotsford

The Sumas Prairie was one of the parts of the Fraser Valley hardest hit by the 2021 floods that devastated southwestern B.C.

“Given that the risk of climate change-induced flooding is increasing, that area will flood again,” study senior author Tara Martin, a professor of conservation sciences, told Global News.

“In a time of climate crisis, we can’t continue to do the same old thing. We can’t continue to try and keep the water away, keep the fires away. We have to adapt.”

Martin’s study proposes what is known as “managed retreat,” the purposeful relocation of people and infrastructure to safer areas.

The research looked at the cost of buying back just over 1,300 properties in the Sumas Prairie at current assessed values.

Martin said doing so would be cheaper than some of the current proposals to shore Abbotsford up against future floods.

“To buy back all of those properties is just under a billion dollars,” she said.

“When we look at the options being put forward by the city of Abbotsford at the moment, those options range from a couple hundred million up to $2.4 billion.”

5:53 Documentary on the history of Sumas Lake

In 2022, Abbotsford reviewed four options for long-term flood protection, with price tags ranging from $200 million to $2.8 billion — ultimately settling on a hybrid option with a final cost verging towards the high end of the range.

“The cost of managed retreat is within the range of options that are currently being considered by the City of Abbotsford — so it begs the question why isn’t this option on the table?” she asked.

The proposal has received a decidedly cool reception from those working in the agricultural sector in Abbotsford.

Matt Dykshoorn, a dairy farmer on the Sumas Prairie, called it a “non-starter.”

“I put very low merit in the feasibility of it,” he said.

“Financially it makes no sense, from a food security standpoint it makes no sense, logistically, to relocate that many people with an agricultural-based occupation, there just isn’t that much land available in B.C.”

1:59 B.C. floods: Sumas First Nation remembers the injustice of its ‘lost lake’

Jeremy Dunn, general manager of the B.C. Dairy Association, said the proposal ignored the importance of Abbotsford’s agricultural lands.

He added that farmers were looking for solutions that would allow them to stay in place for generations to come.

“This is among the most productive farmland in Canada. It supports dairy farms, egg farms, poultry, multiple commodities,” he said.

“We live in a province that routinely does not have enough farmland and we have a greatly growing population.”

Abbotsford Mayor Ross Siemens echoed those concerns, saying reflooding the lake would have a huge impact on B.C.’s ability to produce its own food.

“Our responsibility is to ensure that our community infrastructure protects our community and residents … which is why we are looking at flood protection measures versus re-flooding options,” he said in a statement.

“Re-flooding would be an entirely different direction and one that would involve all governments.”

Martin said there is no question that re-flooding the lake would come with trade-offs. But she noted the province has been willing to make those trade-offs with agricultural land for other projects such as the Site C Dam and the Trans Mountian pipeline expansion.

9:49 B.C. floods: History of the Sumas Prairie

At the same time, it could deliver other benefits, she said.

Those include environmental payoffs like the restoration of up to 10 per cent of salmon habitat in the Lower Fraser.

It would also mark a significant act of reconciliation with the Sumas First Nation — which historically used the lake as its own breadbasket, she said.

“I recall elders when I was a lot younger talking about Sumas Lake, paddling on Sumas Lake, fishing and hunting on Sumas Lake … they all had experiences on the lake and talked about the bounty of the lake and how important it was to everyone,” Sumas First Nation Chief Lemxyaltexw (Dalton Silver) said.

“Ideally it would be something that would be beneficial to ourselves as a nation, but also to the ecology itself.”

According to Martin, managed retreat doesn’t have to be all or nothing. Various options exist to re-flood portions of the former lake site while keeping critical infrastructure.

“It doesn’t have to be the entire lake,” Martin said.

“We could use some of the existing dikes to manage water flow, but ultimately the water needs somewhere to go, the volumes of water coming down in these atmospheric river events are more than what the current system can handle.”