Just curious: Water landing question

What kind of space does it take to land/takeoff in a plane with
floats? I realize there are all sorts of rules about where one can do
this but I have a relative with a ranch that has a fairly decent sized
body of water on it. This is Texas, so its pretty flat with neglible
trees and I wondered if a plane could be put down there. I tried
looking around a little online but couldn't find anything that spelled
it out.