In recent years, I noticed that some places around Wörthersee in Carinthia have added the suffix “am Wörther See” to their signs: Pörtschach am Wörther See, for instance. Given that the lake itself is called “Wörthersee” that move was just highly confusing with both names showing up on the highway signs. Are there now two lakes? Am I at the right one? No and yes. There is only one lake by that name in Carinthia and yes, you’re at the right one.
Turns out, though, according to this article on ORF.at there is a rule regarding how derived names have to be written. If, for instance, a lake is named after a place, then the name has to be split into two words. E.g. “Ossiacher See” as the name is derived from “Ossiach”. As for Wörthersee, it’s not derived from the place “Maria Wörth” and so the name consists of only a single word.
If you look at some of the websites of the respective towns, the correct name is already used in some places again so I hope it’s only a matter of time until the name will also appear on the street signs (once they have to replaced due to old age or damage). From what I can tell, only Pörtschach is somehow sticking to the wrong name 🤪