Thanks for all the input, it is very helpful.

After reading through the suggested posts, I have a few questions. Someone mentioned that the law changed in 2002. What about it changed?

The only reason I believe the pond was built 2 years ago is because that is what the realtor told me. It is possible that he doesn't really know. The arial photos of the area are from 1999 and clearly there is no pond.

The stream that is dammed flows into a larger creek, which I don't believe is navigatable. I assume this because the bridge that is a few hundred yards upstream is so low that you could never get under it in a boat. (does this matter?) This larger creek then flows into a very large river that is navigatable, no question about it. Would any of this make a difference in the legality of the dam?

Suppose that the current owner didn't go through the permit process but should have. Does anyone have any idea what my responsibilty is if I then buy it? This whole thing has started me wondering if many of these ponds out there are not legal. But I wonder if any governement agency is out there activily trying to enforce these laws.

Thanks again for all the input, this site has been very educational.