There shall not be more than one principal structure
on each lot in any zone, except as permitted for development groups.
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
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. No building,
structure or other impervious areas shall be permitted to be constructed
within said easement or restricted area.