In this day and age I would firstly set up game cameras that link to cell phones to advise you immediately of trespassers and even without that I would put up signage to that effect,, let people know that they are on camera and reported, not in a couple weeks when you check your camera but are being watched and recorded live, right at this minute, and law enforcement is on the way even as you read this.
My biggest beef I have with it is the disrespectful rifraf that trespasses,, there is a private lake here local that a lot of people sneak in and fish, it is owned by a municipality that really doesn't care, just puts up no trespassing signs for liability reasons, but they leave piles of soda and beer cans, Styrofoam worm boxes and every other piece of trash they can find to throw down, absolutely disgusting. how can anybody be that worthless?