I built a lake in Alabama about 10 yrs. ago. We had to get a permit from the Corps of Engineers and one from the Ala. Dept. of Environmental Management. The Corps never gave us any trouble, but ADEM came by once a month to check everything. I'm sure Alabama is not as environmentally strict as NH. Good luck. It was totally worth the effort, building the lake, but rest assured, it was definitely a "labor of love".