Lac Bromont, Quebec, Canada

Lac Bromont is a popular recreational destination for both Bromont residents and visitors from surrounding areas. The lake is located 85 km to the east of Montreal.

In recent years, the lake has experienced a decline in water quality and the Lake Stakeholders Association (Action Conservation du Bassin Versant du Lac Bromont (ACBVLB)) and the City of Bromont (Ville de Bromont) were keen to undertake measures to improve water quality in the lake. 

A five-year study undertaken by the Université du Québec à Montréal (UQAM) had demonstrated that sediment phosphorus release was the main source of phosphorus, contributing up to 80% of total Phosphorus concentrations in the lake. As a result, a decision was made to apply 174.3 tonnes of Phoslock in October 2017. 

In the first year after treatment, deep-water phosphorus concentrations had already decreased by 70% and the trophic status of the lake shifted from hypertrophic to meso-eutrophic. 

The City has mandated the ACBVLB, in partnership with researchers from UQAM, to continue monitoring   over the coming years.