I am not taking the time to look up a footnote or any such proof, but I have read (in more than one source) that the lake was named after a French nobleman (le Duc de Pontchartrain or some such), who was a patron of the colony but who never crossed the Atlantic.

There was speculation in one of the other threads that the lake's name was a composite of "Pont" ("bridge") and "Chartrain" (another French name). That may indeed be the derivation of the Duke's name, but the colonists named the lake after someone named Pontchartrain.

Detroit, far to the north, was another French settlement, so it is possible that the same person was the namesake of the fort up there. I believe that there is a present-day Hotel Pontchartrain in Detroit.

"Creole" has had various meanings over the years, some of them mutually exclusive. The original meaning was to describe persons of the first generation born in the Western Hemisphere of European colonists. There may have been controversy from the very beginning over whether one or both parents had to be Europen/Caucasian for the term "Creole" to be properly applied.

At this late date, it seems silly to declare that one or the other of the many meanings is "wrong." Most of the meanings have some connotation of urbanity or sophistication: as applied to cuisine, for example, Creole cooking is refined, Parisian -- stuff that would be served in white-tablecloth restaurants -- as opposed to Cajun cooking, which is rural and home-style. New Orleans Creole society, both white and black, was/is aristocratic or at least pretentious.

The one exception is one of the most common contemporary uses, where the term "Creole" is applied to the French-speaking black country folk of southwest Louisiana.

The Creole girl in the song may be a blonde in this version, but in most of the others, she is described as "dark" and her hair color is not mentioned. So, once again, a "Creole" person might well be either white or "colored" (i.e., mixed Caucasian/African -- mulatto, quadroon, octoroon, etc.)

Incidentally, the old French colonial tradition of the Quadroon and Octoroon Balls reveals a great deal about white and non-white Creole society. This would be a pretty long discussion that I'm not about to start here and now, but if someone just asks... (Or, just Google "Quadroon Ball" yourself.)

The plural "Lakes" appears in other versions of the lyrics, not just Sam Henry's. Many singers substitute "Banks" (much more often than trying the singular "Lake").