Translation: Alexandre Hackett 

If you live in West Bolton or St-Étienne- de-Bolton, you may not be aware that nearby waterways can have an impact on the quality of the water in Brome Lake, many kilometres away. Well, consider yourself educated! The streams of Brome Lake’s watershed, where these municipalities are located, all flow into the lake and influence the quality of the water. 

Coldbrook and Quilliams streams: important sources of phosphorus.
A watershed is in fact a territory in which runoff and underground water sources flow towards a same point. Brome Lake’s watershed covers 186.7 square kilometres and includes eight municipalities, either partially or completely. They are: West Bolton (43%), Brome Lake (31%), South Stukely (18%), Saint-Étienne-de-Bolton (5%), Shefford township (2%), East Bolton (0.5%) and Waterloo (0.07%). The basin is comprised of various streams – including Quilliams, Durrell, Coldbrook, Argyll, McLaughlin, Inverness and Pearson – that all flow into the lake. These streams are themselves fed by smaller waterways upstream. “It’s like a set of Russian dolls – there’s a hierarchy!” says Alix Tremblay, communications officer for Renaissance Lac Brome (RLB). “We start with little streams that flow into larger ones to eventually end up in the lake”. 

Quilliams and Coldbrook streams by themselves contribute 75% of the phosphorus entering Brome Lake. This phosphorus contributes to outbreaks of cyanobacteria. It mainly comes from agricultural lands (13% of the watershed) and areas linked in one way or another to human activity (8% of the watershed). In this way, pollutants, sediments, suspended matter etc., regularly flow towards the lake. “These rivers are not by themselves all that polluted, but they transport large volumes of water. Their impact on the lake is therefore significant.”

A shared responsibility
Given this context, RLB, which works for the conservation and preservation of Brome Lake, has set up numerous projects within the watershed area, such as: the cleaning of Coldbrook stream, the measuring and stabilization of the shores of Quilliams stream, an inventory of private ponds, an autodiagnosis of the shorelines in agricultural areas, and following the quality of runoff water, etc. It’s safe to say that the residents and companies active within the Brome Lake watershed, along with the people living on its shores, are responsible for the preservation of their waterways, so that we can all continue to take advantage of clean and clear water.