(a) Except as provided in subdivision (c) of this section, the shoreline lot width restrictions apply to any lot, parcel or site which adjoins or includes a shoreline, or is located in whole or in part within the applicable building setback distance.

(b) The shoreline lot width restrictions apply to all new single family dwellings or mobile homes, including those to be located on lots created by a subdivision by gift, devise or inheritance, and on lots in preexisting subdivisions which have not received New York State Department of Health approval.

(c) The shoreline lot width restrictions shall not apply to subdivisions which do not involve the construction of any new single family residence or other new principal building, such as a subdivision solely involving existing buildings, or a subdivision of land for a boundary adjustment.