Originally posted by K & L
There is motion sprinklers that you can setup. When the cat triggers them, he'll get wet and not hurt. Trust me, after a couple times he will avoid the area.
We got that for our pond and it worked great. We love our cats put didn't like them going after the ducks. So no only did it keep them out of the pond, now they stay away from the ducks, in the pond or out.

We got it from Dr. Foster and Smith pond catalog. You can find them on line. If nothing else it's a good way to water your plants around the pond.