Hi there, you keep saying that this pivot "overhangs" your property. Maybe a photo would help, but do you mean that physically the end of the pivot is actually on your property? If so, is there legal right in your state to do so, an easement, license or other permission? If no, then neighbor has no right to do this, and an extra tall new fence post is in order. You will have to decide if neighbor has had enough time after notice to fix the problem. I know it doesn't sound neighborly, but sounds like your neighbor is not neighborly. Now, if its just the water being thrown far enough that it lands on your property, idk.