When I built my pond I called the county Soil and Water dept. and they sent a guy out to look over and discuss the site. He basically said I didn't need a permit or anything else since my dam wasn't over 5', over so many acres, etc. but I would need to get an easement from my neighbor to put the pipe in for my overflow and then go ahead and build. My neighbor said to go ahead and put the pipe in but he wouldn't sign an easement. It turned out that while digging my pond we found an old tile that went from my property through his therefore giving my an "implied easement" I built the pond and put in the overflow tile. I didn't get anything in writing from soil and water saying I was allowed to build the pond and I assuming you didn't either. I'm not sure it would do any good but it wouldn't hurt for you to get some sort of evidence that they gave you the go ahead, for example, a recording.
