I'd guess that 'Downriver to the Sea' is just a sub-title deriving from the use of the tune as part of the incidental music in a 1997 American PBS documentary, Lewis & Clark: The Journey of the Corps of Discovery, and has no other bearing on this discussion. Now would be the time for somebody (ideally 'sciencegeek', who asked the question in the first place) to provide in full whatever information 'Bare Necessities' provided in their sleeve notes.

What exactly did they say? Exactly what source and/or copyright information was given? Please, when asking a question, tell us what you already know. It saves people wasting valuable time following up false leads (like the much later Irish song mentioned earlier) or filling in gaps that needn't have been there in the first place.