In the spirit of that no trespassing sign, it doesn't hurt to do some target practice every time your at your pond, the sound of high powered rifle fire can be a deterrent.
We shoot often on the property and near the pond so this should be covered.
My rule - never , never ever approach a trespasser unless you have the ultimate advantage. A marksman buddy with a rifle and a clear view to cover you is a good start. With all the nuts out there you had better be ready for anything if you are confronting them.
I had my rifle, a side arm, and a nearly black belt 10-year old at the ready.

I put on my happy face and ask them to leave. So far, no repeat offenders.
If little ol' me scared them off the first time, this dude would scar them for life.
