Well, that rules out that as an access through about 90 percent of the "rivers" in the prairies. Most only have flow, let alone enough water to make it worth dragging a canoe into, during the spring run-off, or in the after-effects of a massive rainstorm cell in the drainage basin.
Really needs a definition of "navigable" to mean anything. I didn't dig around the site, to see if it was there.
Now that there is not a family on every quarter section, there is not the requirement to have road access available, so in a lot of places, the road allowances are being absorbed into the adjecent landowner's properties (and brought into the tax base), so a road allowance on a map is not a sure thing either, unless confirmed with the RM (Rural Municipality) or County. They tend to keep using the maps that they got printed years earlier, until they run out, then they update.
Simple answer, is that there is no simple answer. It really depends on a whole lot of different, overlapping circumstances.
Cheers
Trev