I once knew a fellow who had a temper and he had the same problem. The runoff from the neighbor would fill up his yard.

BS he says. He has a cement contractor come in and put a full curb between his property and the neighbor's property so that there was zero runoff. Boy was the neighbor pissed. Now, the neighbor developed the lake.

Of course, you would need to be the type that didn't mind a cement curb in your backyard.