Given the profile of the PFAS in the La Baie water, contamination by firefighting foam is plausible. Contamination by a landfill site is not plausible, because the bouquet of PFAS would be more complex if it was old PFAS.
Now, do the firefighting foams come from Bagotville or not? I can't confirm it by doing a water analysis. However, the profile of the PFAS in the water is compatible with the profile of the PFAS found in the firefighting foam.