Thanks for all that info about the difficulties of winter navigation on the St-Lawrence.
It is a highly under-exploited natural resource " A path that walks" used to say the natives that dindn't have to paddle to travel!
When comparing with European waterways economics; massive benefits, not counting social and environmental advantages would result if this country Canada and Quebec in peculiar could get around the still foggy " roadblocks" consisting of
opposing financial interests and lobbies, obsolete regulations and lack of government vision.