Face,
Talk to me either here or in private. I had a dam on the original creek(on my property) and one deeper on my property feeding the pond. You need both to maintain the water level where you may want it. I ran and am still running into so many bad neighbor issues that you would not believe. I also had an easment signed and still things got out of hand. I can't tell you enough not to go this route. If you need to tap into the creek then do so, but plan on the water being no higher than the normal creek level. Then you will have very little issue and the neighbor can not come back easily and do anything. I can tell you that even after I brought mine down to normal creek level the neighbor was still irrational and has re-routed the seasonal creek to have it avoid coming onto my property. I have thus spent a bit of money and time piping alternative water supplies to my pond. He had also tried some things that I mentioned earlier about contaminating and putting things into my pond that would cause problems.
Best answer is to not go down that path if you dont have to. Just my $0.02
