So, being one of the streems on the publicly owned streambed list, I was allowed to be up to the high water mark? The guy told me he owned half of the stream bed due to his recent land survey.
Only a judge can answer. It'd essentially be a property dispute. The bottom line is that you have valid reason to believe it's public property and you can be up to the high water mark. And he has reason to believe he owns the streambed, and you can't be there. Here's the deal.
The guy's deed very likely says he owns half the streambed. He probably is not lying about the land survey. And if you choose to fish there, he may very well choose to prosecute you for trespassing, and the police likely would not throw it out immediately.
If that happened, you could just pay the fine, and that'd be the end of it. Or, you could choose to fight it on grounds that the stream is navigable, and thus the streambed is public as the DCNR asserts. Assuming the landowner doesn't just drop charges at that point, it'd go to court. You'd both have to lawyer up.
In court, the judge would try to determine whether the stream is navigable. The DCNR's list means absolutely nothing on it's own. But it does likely mean that the DCNR was able to dig up some evidence of past commercial navigation on that waterway. Back in the 1800's many goods were transported by water, rather than horse drawn carriage on crappy rutted up mud roads that were often impassable.
The test of whether it's navigable is whether it is or ever was "capable of" being used for navigation in it's ordinary state. A past history of navigation, like the DCNR likely found, is pretty convincing proof that it was. And thus, presenting that same evidence, a judge should rule in your favor. You would not be charged with trespass. A judge may or may not order the landowner to back pay your legal fees. The landowner, and all others on that particular stream, would have to cede their claim to the streambed up to the high water mark, as the streambed itself is deemed public property. Landowners, though, may petition government for a reduction in their property taxes, or even a refund, since they don't really own as much as they thought, and thus have been overpaying property taxes all these years.
Or they could appeal to a higher court. And you go through the whole rigamarole again.
Or, ya never know, judges come in all sorts of persuasions, and court cases are rarely so predictable. And example of what could go wrong for you: precedent from past cases says a stream navigable in part is navigable in whole, but nowhere in congressionally passed statutes is that stated. So a judge could, in theory, disagree with past judges, break that precedent, and claim some of the stream to be navigable, but not the particular part you were on. In which case, you're guilty, out your legal fees, PLUS possibly the landowner's legal fees, plus whatever fine or form of punishment there is for trespassing.
Or you could appeal to a higher court. And you go through the whole rigamarole again.
Fun, huh?