This might seem like a strange question, but is there any way to get the Nelson River and the main lakes of Manitoba to be a busy shipping route? Another route to get to those lakes works, but getting heavy shipping into Lake Winnipeg and neighbours is what I'm most interested in.
Short answer: no
Long answer: If you wanted to build something that would take shallow draft steam boats, sure. Some locks and a little work could probably get you that.
If you want oceangoing ships? Ouch. We're talking having to excavate a channel through, not dirt, like Panama, but Precambrian Shield rock.
By the time that there was any reason to do so (late 1800s), it's easier to build a RR, which they eventually did. (Well, to Churchill, not Ft. York, but to the Bay).
Remember that you can only get shipping into Hudson's Bay a couple of months a year, so it's effectively useless for military purposes.
As for shipping produce out, there is a massive inland terminal at Churchill for grain. In the 70s (?) there was a big scheme to get Prairie grain out through the Prairie Provinces, not making the Ontarians in Thunder Bay rich, and avoiding the Rocky Mountains and the Crowsnest Pass (and the infamous Crowsnest Pass rates which the railways tried constantly to get out of). So, firstly it was a regional patriotism kind of thing, and secondly, it really is a shorter route to Russia (then a major importer of wheat from Canada). Still, it never was entirely commercially viable.
Why would anyone try?
