Notwithstanding any other provisions of this Chapter, no building or structure shall hereinafter be erected, moved, altered, added to or enlarged within a distance of 25 feet from the mean high-water mark of a watercourse or other body of water. In addition, an easement of not less than 15 feet along each side or edge of said watercourse or other body of water shall be provided. Unless specifically permitted elsewhere in this Chapter, no building, structure or other impervious areas shall be permitted to be constructed within said easement or restricted area.