Watershed management: the big and the small

I live in the Shawnigan Lake watershed – a 110 km2 parcel of land edged by the hilly topography of the glacially scraped coastal hills, with the jewel of Shawnigan Lake nestled almost directly in the middle. The lake is a key drinking water source for many who live along the lakeshore, though it sees extensive recreational use. I enjoy paddling in it and taking the dogs to swim in it, despite the relatively limited public access.

The Shawnigan Lake watershed, mapped by the BC Ministry of Forests.

For over a year, residents have been fighting against the construction of a contaminated soil dump in an old quarry at the south end of the watershed, near one of the main inflows to the lake. It seemed last spring that the fight could be won, when the BC Environmental Appeal Board (EAB) agreed to review the case. But just a few weeks ago, the EAB ruled that – despite the concerns of the Shawnigan Lake Residents Association and the Cowichan Valley Regional District about the potential impacts on drinking water – “the geology and hydrogeology of the site and the facility design, together with the permit conditions, will provide the required protections.” The project was given the green light to proceed.
Regional residents have been hugely engaged in this process, with over 200 coming out to hear the EAB’s decision. And they’re understandably up in arms. This has been a long battle, and the EAB decision doesn’t inspire confidence. The assumption that the soil dump will have no impact on drinking water is based partially on the conditions of the permit, such as using pit liners and only taking in soils that contain non-leaching contaminants.
When it comes to water, however, the precautionary principle seems to be a good approach: wouldn’t keeping the contaminants out of the watershed in the first place, rather than depending on an engineered barrier to keep them out of the water supply, be a better long term course of action? It also doesn’t help that the proposal was reviewed under the Environmental Management Act as opposed to the Water Act (which has, incidentally, recently been revamped).
It’s fantastic to see so many people concerned about water (and you’ll know what I mean if you happen to pass through our neck of the woods and see all the ‘Save Shawnigan Water’ posters and bumper stickers). Hopefully they’re also aware that water quality isn’t just about the big projects like this contaminated soil dump. While these are the most visible impacts, water quality can be subject to ‘death by a thousand cuts.’ And there are many such potential wounds in our watershed, just not on the same scale – or with the same profile – as the soil dump project.
Consider, for example, all the people in your neighbourhood who have horses and other livestock. They produce a lot of waste – and depending how that waste is stored, it can leach into the water table during our winter rainy season.
What about people like my neighbour, who have a dead car graveyard in their backyard? Think of all the fuel and other vehicle fluids that leak out into the underlying soil over time, also making their way down through the water table.
Then there are the larger agricultural operations in the area: vineyards, dairy farms, blueberry farms. What practices are they employing that either help – or hinder – water quality in our watershed?
And let’s not forget about Shawnigan Lake itself, ringed with private residences, like African wildlife clustering around a watering hole. First there are the recreational uses. Given that power boats are permitted on the lake – and it has more private docks than you can count – you can bet there are spills of fuel and oil into the lake on a regular basis.
A 2003 report from BC’s Ministry of Environment noted that – while water quality has overall remained good from the 1970s to 2003 despite increasing development in the watershed – ‘on-site sewage disposal systems’ (aka septic systems) could be increasing bacterial counts in the lake beyond safe drinking water guidelines. Lakeside residents aren’t the only ones with septics – most of my neighbourhood relies on individual septic systems, and who’s to say they’ve all been installed correctly and are working as they should?
Closeup of the north end & west arm of Shawnigan Lake from Google Maps. Note the shoreline development and private docks.

When we consider each of these impacts individually, they seem quite small. A cup of fuel here, a winter’s worth of horse dung there, a few dead cars somewhere else. But when you add them all up, the impacts can be significant.
Of course it all depends on the hydrology and hydrogeology of the watershed, which determine where all these contaminants go when they’re mobilized via hydrologic pathways. It may be that some contaminants are contained in the upper soil layer, prevented from reaching the groundwater table by underlying bedrock. Or that surface runoff is insufficient to transport some contaminants all the way to the lake itself. In other cases, however, contaminants could be perfectly situated for transport to the lake – either via groundwater or surface water pathways.
An example of how the ground surface is connected to aquifers – this is how contaminants move from surface to subsurface environments (from the USGS).

The contaminated soil dump is a single, high-profile issue that highlights the uncertainties inherent in deciding how best to maintain good drinking water quality in the watershed. Let’s not let it distract us from the broader range of land uses that can adversely affect water quality in our watershed. Rather, let’s hope it keeps us all focused and aware of the myriad ways in which our water can be affected.

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