Well it happens that I know that park very well and the boundaries are sketchy at best, I also know every landowner along that stretch of the stream, and I know they don't just tell people to leave for know reason, so it is very similar to the situation on that Bucks County Stream. Everything on the Perky is private property, except for a very short section of township owned land. There are sections there that in the past were open to fishing but are not now, like the property immediately above the park.
Funny that I should remember your post a little differently. I also remember that someone asked exactly where you were fishing, and didn't get an answer.
I've worked with those landowners for years getting access and doing streamwork, I was very interested in what happened, if there was a landowner problem.
The point is no matter where you think you are make sure of the access.