One of the tests for navigability is a stream being used for commerce, but I don't think a mill would qualify. What is meant by commerce in this case is, is cargo hauled downstream or upstream on the waterway. Was it ever used for travel by boat is another test.
Taken to the extreme, nearly every stream in the Commonwealth was at one time used to float logs(commerce), but that in itself doesn't neccessarily mean the courts will rule in favor of navigability. However, The courts have never taken away the Commonwealth's right to the water. This goes back to the beginning of the Commonwealth and Colony. And the Commonwealth can never give up it's right to the water. So in a way it's a taking by the landown to close his water, but he can't close it anyway unless he owns the land on both sides, he can only close his side. But you have to know this before you walk through.

I'm sorry but I really doubt most land owners in this situation are even familiar with navigatable waters. A simple knock on the door or a note left with your name address and phone number could clear up the issue.

Who needs lawyers and their bills,..... or the government for that matter.

just thought of an awsome idea get a group of guys to run around the state paddleing all the streams offering guided trips , use public put ins and take outs boom commerce and travel and with the depth clearcence of a yak anything over six inches of water will be nav

Not sure a bunch of yaks would be considered commerce. It'd be a hard sell to say that recreation, even if there's money involved such as guiding, is a form of "trade" over a public highway. They're looking for a history of commercial transportation of goods.

Commerce of the times was usually animal skins dried meat maybe corn traded between the Lenni Lenape or Shawnee this is how far back some streams are noted to my understanding

Yes, but all that matters is what happened after the revolutionary war! Mostly, we're looking at the 1800's for the timeframe of interest, after trade in the new world was well established but before trains and roads became the primary vehicle to transport goods.

Roads weren't exactly good. Most everything was traded on rafts/barges via waterways, from food and dairy to coal, oil, and timber.

Actually navigability goes back to when PA was still a colony. The laws of navigability go back to Enlish law.
But we don't need to make a stream navigable to have some fishing, a simple knock on a door or 2 will do in most cases.