An article by Beals et al in the 1964 Journal of the RASC article (below) proposed that Lac de Courval may be the result of a cosmic impact. This report was published before any geological studies were performed at the site in order to find impact features.
A later magnetic survey to find impact related geology was NEGATIVE. I have not found any reports describing the surveys performed at this site.In conclusion, a remote possibility exists that this structure is impact related.
Beals, C. S., Ferguson, G. M., & Landau, A., [Scientists Report II.] A Search for Analogies Between Lunar and Terrestrial Topography on Photographs of the Canadian Shield, Part II,Journal of the Royal Astronomical Society of Canada, Vol. 50, p.257-258