Rising waters, pollution spillover, and salmon habitat in the Sumas Lake area of the Lower Fraser Valley: The catastrophic ‘atmospheric rivers’ of 2021

Sampling water to better understand the true extent to which the floods unleashed pollutants into local waterways.

November of 2021 was a month like many others for the temperate rainforest of coastal British Columbia – variable winds from the Southwest, skies grey, and an abundance of … precipitation. What set this year apart was the cumulative amount of rainfall in Vancouver – 312mm for the month of November – well above the average of 209mm. The atmospheric river was incessant, saturating watersheds throughout the region, culminating in the breaching of the Nooksack River in Washington State, with flood waters rising in many areas, including the Sumas Prairie region of the Lower Fraser Valley. 

The landscape in the Fraser Valley has changed dramatically since settlers first arrived to a world of towering trees, abundant salmon, and vibrant Indigenous communities – and so has the climate. What was once Semá:th Xhotsa, or Sumas Lake, is now known was Sumas prairie, bringing into focus the fragility of human-altered watersheds in the face of episodic events such as the ‘atmospheric rivers’ of late 2021. Drained by large hydraulic pumps installed in 1921, the lake is now a prairie, and no longer supports a rich bounty of aquatic Indigenous foods and migrating waterbirds, but instead supports a diverse crop of blueberries, potatoes, and cabbage. (See maps in What is Sumas Lake? 100 years ago, Abbotsford had a 134 sq km lake (PHOTOS) | Urbanized (dailyhive.com))

As the flood waters rose in late November, farms, industrial sites, and urban neighbourhoods became one through a newly-created complex soup of pollutants. Manure, human waste, diesel, and pesticides mingled, defiant in the face of regulations, targeted monitoring, and best practices that toppled with the rising waters.

“The Sumas Xhotsa (Lake) was once relied upon by our ancestors and provided many of the resources required to sustain our people.  The November 2021 flood event demonstrated that the spirit of the Xhotsa is alive and well and that we must learn to harmonize with Mother Nature today.”

Murray Ned, Councillor, Sumas First Nation and Executive Director, Lower Fraser Fisheries Alliance.
Barrowtown facility in the Fraser River Valley.
Barrowtown Pump Station. Photo by Alex Harris / Raincoast Conservation Foundation.
Group of people working together collecting water for sampling.
Photo by Alex Harris / Raincoast Conservation Foundation.

Water sampling

We arrived on scene on December 15, 2021, after the Barrowtown Pump station had managed to quell the onslaught of water from the overflowing Nooksack River in Washington State to the south. The skies and floodplain were alive with thousands of geese, ducks and swans who appeared to remember the vibrant Sumas Lake ecosystem that preceded the drainage that began in 1921. Our goal – to understand the threat of myriad pollutants to flood-affected areas with a focus on fish (salmon) habitat and the well-being of First Nations communities. 

Our surface water sampling strategy built on a plea for answers from Myles Lamont (TerraFauna Wildlife Consulting), a local biologist who witnessed the early ravages of rising waters, as well as the sights and smells of diesel and debris on the water’s surface. Over the next six weeks, we were joined by colleagues from Sumas First Nation, the Lower Fraser Fisheries Alliance, the S’ólh Téméxw Stewardship Alliance, Fisheries and Oceans Canada, and the BC Ministry of Forestry, Lands and Natural Resource Operations.

Our role was to complement the efforts being led by government agencies and to generate high quality data on contaminants of concern. Our intent was to  better understand what the floods had done to the freshwater habitats of salmon, and to resources long valued by First Nations. The damage to agricultural crops and to homes and property were evident at a glance, but what about the quality of salmon habitat, and the health of sturgeon, freshwater clams, and migratory birds that had been stewarded for millenia by Indigenous people in the Sumas Lake area?

Flood of the Fraser River Valley with a highway running through.
Photo by B.C. Ministry of Transportation from Flickr.
Map of the Fraser River Valley showing where Sumas Lake was historically.
Map courtesy of Sean Moore via the Tyee.

What we were looking for

We were looking for the usual suspects of fecal coliform, metals, and hydrocarbons, but also fertilizers, currently used pesticides, pharmaceuticals and personal care products, perfluorinated compounds and the artificial sweetener sucralose. A comprehensive list of contaminants that we hope to either detect at very low levels or not at all. Data are forthcoming, pending a detailed analysis at dedicated laboratories. 

While we cannot predict now the extent to which the floods may have unleashed a torrent of pollutants into local waterways, one thing is certain: they are there and we will find them.

Thank you to our partners and funders

Pacific Salmon Foundation
BC Environment
Fisheries & Oceans Canada
Lower Fraser Fisheries Alliance
S’ólh téméxw Stewardship Alliance
Sumas First Nation

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Our new mobile lab will enable the Healthy Waters Program to deliver capacity, learning, and training to watershed-based communities. We need your support to convert the vehicle and equip it with lab instrumentation. This will allow us to deliver insight into pollutants of concern in local watersheds, and contribute to solution-oriented practices that protect and restore fish habitat.

Sam Scott and Peter Ross standing in front of the future mobile lab, which is a grey sprinter van.