this is not good. are other homes on this pond also, and are they having the same problems? Did you not know this before buying?
My first attack would be diplomacy and documenting all contacts and all replies and just testing the waters for some sort of understanding and attempts to remedy this. Take many pictures of the situation also.
When all roads lead to a brick wall and you feel that you have had enough time for a fix or remedy, then seek councel. This could take you a very long time. Be ready for the long haul.
Jason might shed some additional light on your dilemea.