A drained lake, a re-routed river, and the rain: the deep roots of the Sumas flood crisis

Sumas Lake once covered much of the Fraser Valley's fertile farmland. This is the story of how it disappeared, how it could re-appear, and some of the challenges ahead.

By Tyler Olsen | November 17, 2021 |6:35 am

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By Tyler Olsen and Grace Kennedy

To understand the flood crisis currently gripping the Sumas Prairie area in eastern Abbotsford, you have to understand the history of the area, and the roles played by the Nooksack River and what was once Sumas Lake. You need to know why Barrowtown Pump Station exists. And you need to know why, if it fails (and maybe even if it doesn’t), the lake will return.

More than eight millennia ago, ice covered the Fraser Valley. But change was in the air and on the ground. The glaciers were melting, and as they receded, they left behind a valley and an early lake between what we now call the Sumas and Vedder mountains. Small watercourses ran along the newly exposed ground of clay and gravel, and silt, feeding a growing lake. The most important of these early watercourses was the Nooksack River, which flowed north from the foothills of Mt. Baker, delivering thick, fertile layers of volcanic sediment.

The lake grew, particularly after the collapse of an ice dam on the Chilliwack River. A short river allowed it to drain into the Fraser River. Spring and fall freshets would send water back into the lake, causing it to expand with the seasons.

Higher, then lower: the Sumas Lake’s seasonal ebb and flow would play out for thousands of years. The lake expanded when it rained hard—spreading through a wetland ecosystem accustomed to rising water. In doing so, it reduced flooding elsewhere in the region. White sturgeon travelled to the silty lake bed to spawn when the lake was at its lowest. Salmon followed that same path in the fall. The Semá:th people built villages around the lake, following its tides as long ago as 400 BCE.

In one story, shared in A Stó꞉lō-Coast Salish Historical Atlas, a merciless drought left only two survivors: a man and a woman. The pair were separated from each other by great distances, and crawled on their stomachs through the muddy lake floor in search of water. They met at a small pool in the lake basin, and founded the Semá:th people.

“For us, that was our travel routes, that was our economy, that was our food security,” Murray Ned, councillor for the Semá:th First Nation, recently told the Current. “We didn’t have to go too far to access anything else.”

For most of their history, the Semá:th controlled access to the lake, sharing it with other Stó꞉lō communities and the Nooksack nation. When European settlers arrived, they too encountered Sumas Lake. By that time, the Nooksack River no longer flowed north, instead travelling west to the ocean. The lake supported an ecosystem of blueberry bushes, wapato (called an Indian potato by settlers), and blue camas. In 1894, a formidable Fraser River flood covered the valley, and a swollen Sumas Lake extended its shores once again, soaking up water that would have otherwise decimated the new communities.

Camp Sumass, as painted by surveyor James Madison Alden
In a painting of the Sumas valley by American surveyor James Madison Alden, Sumas Lake sits in the background, beyond a line of trees and shrubs.

But the newcomers didn’t like the lake. They hated the mosquitoes. They didn’t use the water. And they were envious of the extremely fertile soil at its bottom.

“The Dominion lands in and around Sumas Lake were useless and unsuited for homesteading,” the Chilliwack Progress reported in November 1912. “The reclamation of these Dominion and private lands would be a great boon to the Fraser Valley and the whole province, not only on account of the large area of now useless Dominion lands that would be rendered fertile and productive, but the enhanced value and usefulness of the still larger area of private lands.”

Sumas map was one of the Lower Mainland's most prominent geographical features before it was drained 100 years ago.
Sumas Lake, seen here in the bottom right quadrant of an early map, was one of the Lower Mainland’s most prominent geographical features before it was drained 100 years ago. 📷 City Vancouver Archives: AM1594-: MAP 2

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The end of Sumas Lake

So, almost exactly 100 years ago, engineers drained the lake. Or, rather, they pumped water out of the lake, as one must do when a lake bed is lower than all the land surrounding it.)

The engineers created a series of drainage ditches, dredged what we now know as the Vedder Canal to reroute the Chilliwack River, and constructed a large pump station to lift water up and into the Sumas River. That river joined with the Vedder shortly after the pump station, and from there the waters flowed north into the Fraser.

The system was a boon for farmers, but devastated local First Nations.

“They took the lake away and we never got one inch of it,” former Grand Chief Lester Ned told the Vancouver Sun in 2013. (Ned died in October.) “I don’t know how the people survived way back then.”

Despite early problems, the elimination of the lake eventually achieved many of the goals of those who had advocated for the project, providing vast spaces for settlement and farming. When floods happened—like in 1990, when the Nooksack spilled its banks, flowed north to Canada and closed Highway 1—the lake didn’t re-form. That event did briefly remind people of the twin threat posed by an American river and an extinct lake. But not long after the water receded, people’s attention turned elsewhere. Mother Nature had supposedly been tamed.

Barrowtown Pump Station uses four pumps to move water up from Sumas Prairie to the Sumas River. It was built in the 1980s.
Barrowtown Pump Station uses four pumps to move water up from Sumas Prairie to the Sumas River. It was built in the 1980s. 📷 City of Abbotsford

A problem of nature

The problem then—and the problem now—is physics. Sumas Lake existed for thousands of years the same reason all lakes exist: gravity. When it rained in the Fraser Valley, water ran down the sides of Vedder and Sumas mountains and collected in a shallow basin in the centre of what is now the eastern Sumas Prairie. And when the Fraser rose, it also pushed water into that basin. This was what made Sumas Lake a lake.

The bottom of the lake bed lies roughly at sea level, below the surface level of the nearby Fraser River. Only when enough water fills the prairie to a level equal to the Fraser does the lake begin to naturally empty into that river (via the Sumas River) and then toward the sea. When the Fraser is higher than Sumas Lake (as is the case right now), then water from the Fraser helps fill the lake.

That is how things worked before the lake was drained. For the last century, huge pumps have been responsible for keeping the prairie more or less dry. The original pump station was replaced by the current Barrowtown Pump Station in the 1980s at a cost of $27 million. Today’s facility has four massive pumps to suck water out of the prairie’s fields. On sunny days, only one is needed. Those pumps can usually keep up with the water that flows into the prairie.

But these are not usual days. As we write, late on Tuesday evening, officials say the pump station may soon be swamped with water, forcing the pumps to stop, and for water from the Fraser to begin flowing into the old Sumas Lake bed.

Here we return to the other big cause of much of the flooding being seen on Sumas Prairie: the Nooksack River.

It is the Nooksack’s flood waters that are largely to blame for the current mess that has isolated Chilliwack from Abbotsford and driven thousands from their homes. It’s also the Nooksack’s floodwaters that have swamped the Barrowtown pump station, leading to its possible failure. And yet, many will still not have heard of the Nooksack: a river that runs from the banks of Mount Baker, through northern Washington and empties into Puget Sound without ever crossing into Canadian territory.

The river once flowed north, through the Sumas valley to the Fraser. Now, it charts a half-circle that ends in the Pacific Ocean, just north of Bellingham. No one knows for sure when this shift—or “avulsion” as hydrologists call it—took place. One theory has the change taking place thousands of years ago; another suggests the evidence points to a much more recent change in course.

These images, f
The Nooksack River once flowed into Sumas Lake, before changing course, as illustrated in these images contained within a Whatcom County report on the history of the geologic history of the Nooksack. 🗺 Whatcom County

What caused the avulsion is also unknown: it could have been a debris flow from the mountains; it could have been an epic flood. But when the Nooksack did make a left turn, its old streambed to the north turned into the relatively tiny watercourse that is now the Sumas River. The change also created a lasting threat: ditches that today flow into the Sumas sit barely 200 yards from the Nooksack. So whenever the Nooksack River floods near Everson, Wash., all the water that spills to the north flows downhill—into Canada and Sumas Prairie.

This threat is not unknown, even if Neil Peters, the province’s former head of flood planning, declared in 2018 that “the Nooksack is probably something people don’t appreciate as much as they should.”

A dike exists to try to direct floodwaters toward north of the Sumas Lake bed and into the Sumas River channel. After the 1990 flood that submerged farmland and closed the highway, an international task force was created to tackle the challenge of preparing a response to a flood that might affect both Canada and the United States. Nothing came of that group. And as the memory of the flood receded, so too did the urgency to prevent another one.

Still, the City of Abbotsford has recently increased its focus on the Nooksack River. In 2019, the city received money from the federal government to study the issue, and a report was tabled last year. Its findings were stark: although a small flood like the one in 1990 could be contained, a larger one that breached dikes had the potential to refill Sumas Lake and leave parts of Sumas Prairie under more than three metres of water—enough to submerge homes, destroy property, and kill untold numbers of livestock.

A report last year illustrated the scale of flooding possible if a dike failed. The failure of the Barrowtown pump station, at the top of the map, could lead to even worse flooding.
A report last year illustrated the scale of flooding possible if a dike failed. The failure of the Barrowtown pump station, at the top of the map, could lead to even worse flooding.

The damages could exceed $500 million. Sumas Prairie is one of the most productive farming regions in the country, home to thousands of cattle and millions of chickens. Much of BC’s milk, dairy and poultry come from the prairie. The country’s main highway runs through the valley. So do pipelines and key power lines. And more than 3,000 people—plus an unknown number of migrant farmworkers—call it home.

The report had no short-term solution. The cheapest and most effective potential solution entailed helping the Americans improve flood protections adjacent to the Nooksack. And that, like anything to do with international politics, isn’t simple.

Story continues below.

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Gravity exerts its will

By Tuesday afternoon, the situation in Sumas Prairie was mimicking the worst-case scenario envisioned in last year’s report. That scenario involved the breach of the long diagonal dike meant to direct floodwaters north of the Sumas Lake bed.

On Tuesday afternoon, Abbotsford Mayor Henry Braun told The Current that floodwaters were racing over the dike and that breaches could be possible within a couple hours. Assessing any damage, though, would need to wait until the waters recede. But the prognosis from Braun was dire.

“The water started to back up when it hit the Sumas River dike. And that dike will hold the water I think probably five or six feet [deep]. But it’s overtopping from the helicopter, so I’m worried. I’m worried there’s going to be a couple breaches in the not too distant future. Like in the next hour or so.”

An evolution of the Sumas crisis

But there was also some hope, with Fire Chief Darren Lee saying the Nooksack had “gotten back in its course.” The situation was still worrying: all the water that had already spilled over the banks would still move toward the northeast. But at least the tap had been turned off.

Five hours later, though, the city issued a dramatic warning that the Barrowtown pumps were expected to fail within seven hours, and the result would be “catastrophic.”

Water from the Fraser River was threatening to swamp and overtake the pumps at Barrowtown. The city, contractors, and emergency workers were doing their best to forestall that situation. But Braun warned that if water began to enter the pump station, the pumps would have to be turned off, and the Fraser would start pushing water into Sumas Prairie from its end. Sumas Lake would start filling at a rapid rate.

“If those pumps go down for any amount of time…What was two-thirds of Sumas Prairie was once a lake. That lake will return.”

Mother Nature and gravity are not easily defied.


This story draws on a range of sources, including interviews, items linked in the text, and Chad Reimer’s terrific book, Before We Lost The Lake. For photos, we referred to this piece at AllLitUp.ca, and this piece at BikeAbbotsford.com.  The main image comes from The Reach Gallery Archives. They have other photos of Sumas Lake here. The Vancouver Archives also has several Sumas Lake photos.

To keep up to date with the Current’s coverage of the Fraser Valley flood, subscribe below. You can also check out our flood webpage, which has links to the rest of our online coverage.

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Tyler Olsen

Managing Editor at Fraser Valley Current

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