Lopatcong is a bit remote, so appreciation upside long-term is probably not going to be as good as areas closer to New York. However, I did a quick search and the house you're looking at is gorgeous. If you don't have to commute a million miles to work, it looks like a great home to live in.
As for the dam, who knows? There's no one alive who will guarantee that a dam won't break. But what are the odds? I'd think you would have a higher chance of a direct hit by a tornado.
I'd roll the dice as long as there was no official evidence that there is a known problem with the dam. You're going to need a riding lawn mower for that beautiful lawn.