Section 68. Bridges spanning canal channels

1. When a bridge spanning the
  Oswego canal or that portion of the Erie canal between the Hudson  river
  and its junction with the Oswego canal, is to be reconstructed, or a new
  bridge  is  to  be  built  over  such sections of the canal system, such
  reconstructed or new bridge shall be so built  as  to  provide  a  clear
  passageway  between  the  bottom clearance line of the bridge, if of the
  fixed type, or the bottom clearance line when raised, if of the  movable
  type, and the surface of the water at its highest navigable stage of not
  less  than twenty feet.  When a bridge spanning the Champlain canal, the
  Cayuga and Seneca canals, or that portion of the Erie canal westerly  of
  Three  Rivers is to be reconstructed or a new bridge is to be built over
  such sections of the canal system,  such  reconstructed  or  new  bridge
  shall  be  so  built as to provide a clear passageway between the bottom
  clearance line of the bridge, if  of  the  fixed  type,  or  the  bottom
  clearance  line  when raised, if of the movable type, and the surface of
  the water at its highest navigable stage, of not less than  fifteen  and
  one-half  feet.   The commissioner of transportation may, however, if in
  his judgment the additional cost is not unreasonable, require that  such
  bridges  be  reconstructed  or constructed to provide a clearance of not
  less than twenty feet or that the substructure  of  such  bridge  be  so
  constructed that the superstructure may be raised to provide a clearance
  of twenty feet without rebuilding the foundation of said substructure.
    2.  The  provisions of subdivision one of this section shall not apply
  to the reconstruction of the State Street bridge, Seneca  Street  bridge
  and  the Buffalo Street bridge, all over the Cayuga inlet in the city of
  Ithaca, county of Tompkins.