It'd be in litigation forever; which is why nobody with the means would try to build something like that today. Even if they could afford the construction, they can't afford the time in court.

Larry Ellison owns a replica Japanese daimyo mansion in Woodside, two mansions on Bellevue Avenue in Newport, and 98% of the island of Lanai...but none of those structures there are (AFAIK) atop a permanent watercourse.