The connections between climate and hidden hydrology is a continuing theme, and inevitably will result in more examples that can be documented making the connections between present and future impacts and historical ecological systems. Each of these has a specific context, which influences the extent of impacts (urban/rural) and the hydrological dynamics (lakes, rivers, shorelines). The recent flooding in November of this year in the town of Abbotsford, which lies near the border of Washington State and British Columbia is one recent example. The connection was made via Twitter by @tornadodc (Lisa Genialle), who posted the following image of flooded highway overpass with the quote “Anyone who knows their local Fraser valley history, this used to be a lake back in the day. Before it was drained to make way for settler farming.”
I had little reference for this particular region or the Sumas Lake specifically, however was supplied with more context via the subsequent thread of responses, many of which yielded Chad Reimer’s 2018 book “Before We Lost the Lake” which explores the ‘biography’ of the lake and its ‘natural and human history’. This provided some much-needed context for what existed and how the flooding takes the shape of this lost lake.
Reimer outlines a similar story found in many locations, a waterway that had been a vital and ecological benefit to the surrounding environment and a resource to milennial of indigenous people, and was summarily ‘reclaimed’ for farmland through drainage, canalization and pumping in 1924. From the review in the Chilliwack Progress: “For thousands of years, Sumas Lake sat near the centre of local culture and life. Then, nearly 100 years ago, engineers drained Sumas Lake, built a canal to harness the Vedder River, and, in the process, radically transformed the area.” A big missing piece of the narrative also covered by Reimer’s book is the displacement of the indigenous people, who have sought compensation for the lost cultural resource, both as a place of hunting, fishing, and gathering that was eliminated when the lake was filled.
Beyond the Sumas First Nation people, the lake is forgotten by most, or at best a historical footnote. As mentioned on the publisher’s site: “Today, few people are aware that Sumas Lake ever existed. The only reminder is a plaque erected on the old lakeshore, at a rest-stop along the Trans-Canada Highway just east of Whatcom Road, on the historic trail blazed to BC’s gold fields. Yet for millenniums, Sumas Lake was a dynamic, integral part of the region’s natural and human landscape.”
The narrative that hidden hydrology is gone but not forgotten is both a cultural phenomenon (in histories and place names for instance), and ecological one (the loss of ecosystem services by removal of function and resilience), and a hydrological one (systems impacted yet still wanting to function and flow as they once did). The extreme storms exacerbated by climate change take shape in these old patterns. For Sumas Lake, a series of maps show the devolution and the impact of the most recent flooding. The first from Wikipedia is an animation of the lakes removal over the years between 1827, the filling in 1924 and the development through the 1940s. It includes the extent of devastating 1894 flood, which was the impetus for the eventual drainage.
From the Fraser Valley News, an undated map (pre-1924) of the lake shows the original extent of the historic shoreline (referenced here as Lake Sumass) which covered between 9,000 and 11,000 acres inside the valley.
The area had been developed over time, starting with transformation into agricultural fields and while mostly rural productive lands, have also since been developed with some other residential and commericial uses. The map below from an extensive analysis of the flooding by the Tyee as part of an article “Mapping the Flood in Abbotsford“, show the original lake, and also showing the dashed line outlining the extent of the 1894 flood within the confines of the valley as well.
The extent of flooding in 2021 came from the Nooksack River and breached the Sumas River dike. The amount of water overwhelmed the series of pumps, which are able to move 250,000 gallons per minute of water, which became unable to keep up with the sheer amount of flooding and the area was quickly inundated, cutting off roadways and stranding people and livestock. The shape of this water corresponds to the former lake bed, with significant depths estimated in a 2020 study to map worst-case flood scenarios, proved to be a hint at what impacts were to come in an extreme event.
The actual flooding is not as bad as the map scenarios above, but did expand into many areas outlined in the former lake bed, the deepest sections potentially inundating more than 3 meters. The post from the Fraser Valley Current shows many of the scenes of flooding near Abbotsford (seen below) which cut off some routes of evacuation, with some people rescued via helicopter. Sparsely populated, the impacts were severe but could have been much worse in a zone of higher population density.
The impacts to property and life are not to be dismissed and my goal here was not to extensively cover the events at Sumas Lake. The bigger picture was that we do need to make the connection between areas where the historical draining and filling waterbodies for progress and development (and often, ironically for flood protection) does have the potential to give hints at the future impacts of extreme events such as the flooding at Sumas Lake, beyond the loss of habitat and other ecosystem services and the lost resource for indigenous people. The photo below, circa 1900 shows the original lake from Daily Hive (which also is a great overview of the lake’s history), which looks remarkably similar to the photo above of flooding here in 2021 (with another major flood in 1990).
The case in point, that water will inevitably ‘find the level’ and create massive impacts, the memory recall I used to outline this post, and this has implications for life and property with real economic and social impacts. As noted in the Daily Hive story: “A 2016 study by the Fraser Basin Council on the Lower Mainland’s flood management strategy estimated that a repeat of the severity of the 1894 flood would currently cost about $23 billion in damages, including $9 billion in losses to residential, commercial, public, and institutional buildings; $7.7 billion in interrupted cargo shipments; $4.6 billion in infrastructure losses; and $1.6 billion in agricultural losses.”
It’s probably too early to tell how large of an impacts was absorbed by the events fall, but history can instruct us in perhaps knowing the location of impacts and using this as a guide for prevention. This is a more rural example, and I’m working on similar urban examples, which, as climate change continues to impact rainfall and other weather events, will be more and more useful in helping us understand, and plan, for what’s next.
Header Image: Sumas Lake circa 1920 prior to drainage – Agassiz-Harrison Observer
An interesting tidbit on this was discovering the amazing Lakes of Washington by Ernest E. Walcott published in the early 1960s which was the basis for much of the bathymetric info included on the King County site and other resources. I’ll expand on at a later date, but in that vein, while outside of the city proper, the range of bathymetric maps, 
