unfortunatly the definition of "navigable" is tied directly to who owns the bed under the stream. This is from the link above:
i.e. " Essentially, the ability of the public to use the stream depends upon who owns the bed. If the state owns the streambed (meaning that the stream is navigable), the public has the right to use the bed and banks and the adjacent landowner may not prevent persons from doing so. See Texas Water Code Section 11.096. If, on the other hand, the private landowner owns the streambed (meaning that the stream is classified as non-navigable)
, the public has no right to use the bed and banks and the landowner may erect barriers to prevent the public from doing so. "
I owned the bed under a body of water that appeared to be "navigable" but the quoted legal definition above helped me beat a miss-informed LEO that thought he knew more about the law and could fish in my yard. He even told me I cold not have a fence up prohibiting his access to it. Not so.. The term "navigable' is really misleading as it sounds like a body of water that you can physically navigate, but in reality it is only referring to who owns the land it is running across. If it is privately owned, it is not navigable. If there are no "posted" signs, then you can access it if you can do so without getting on the land ( from upstream etc. ).
I fish to relax and therefore keep my distance from any body of water I have any questions about or might create stress of any level. I have fished a lot of private tanks, just by knocking on a strangers door and asking. I have even had a couple ask me if I could drop off a few fish when I told them that I typically keep nothing. More than once I have made friends that have asked me back again or to come dove hunt.