Where a boundary line is shown as approximately following the center line of a street or highway, a street line or highway right-of-way line, such center line, street line or right-of-way line shall be construed to be the boundary.

Where a boundary line follows a stream, the boundary shall be deemed to be the center line of the stream. For any lake, pond, reservoir, river or other body of water, the regulations of the district in which they are located shall apply.

Where a boundary line is shown as approximately parallel to a street, highway, stream or railroad line, the boundary shall be construed as being parallel thereto and at such distance from the center line as dimensioned on the Zoning Map.

Where a boundary line divides a lot at the time the line is adopted, the regulations for the less restricted portion of the lot shall extend not more than 50 feet into the more restricted portion, provided that the lot has frontage only on the street in the least restricted zone.