That's something I don't understand about all the witchy/pagan people here in the States. If faeries, witches, and magical/supernatural creatures in general can't cross running water, then how are can they possible be here?
Oh, oh, oh, they say, that's all myth. So it's fucking myth only when it suits them, eh? Because the running water rule predates any sort of organized paganism.
The up-side is that no one in America should fear vampires or other similar ghouls, because they can only cross small bodies of running water -- rivers and the sort.
Witches, we have two options. Real witches: No. Because it's hereditary, and there's no way you could cross an ocean. Which means all witches in America, if we're to insist that they're here, fit into the second definition, which is far more popular: Communing with Satan.
All outdated concepts now because, if we were to actually follow the old religions with any sense of history and how they were, we'd realize that there's nothing magical in America except for scary Skinwalkers and spider women and other horrible indians.
Modern mysticism might as well have "For Entertainment Purposes Only" stamped on it.