This was Fred Eshelmen's mistake in WY. If he wanted to keep his personal access to public land, he wouldn't have gone after the guys corner crossing at all, nor continued to appeal it (although we'll see, he may win still). Most likely, he would have been better off to let them do it and not make a big deal out of it.
I need to read into this issue, I'm not as familiar with how the high water mark is different in swampy states. In the semi-arid west, we don't have these kinds of wetland issues, and I can certainly see how the boundary would be fuzzier. I defer to
@VikingsGuy's analysis.