The county commissioners shall, at the expense of their respective counties, procure such plans of the townships in their counties as may be in existence. If the original plans are not in existence or can not be had at a reasonable price, they shall procure copies of the most authentic plans known to exist. All copies must be on the best quality of linen paper backed with cloth or polyester film with archival photographic image. Suitable filing cases must be provided in each registry of deeds for the reception and preservation of the plans and a suitable index of the plans must be made, having at least both alphabetical and chronological arrangement, and must be revised whenever new plans for recording are received. [PL 2003, c. 55, §6 (AMD).]