Sec 122-631 Nonconforming Uses
   A.   Regulations not retroactive. The regulations prescribed by this division shall not be construed to require the removal, lowering, or other change or alteration of any structure or tree not conforming to the regulations as of the effective date of the ordinance from which this section is derived, or otherwise interfere with the continuance of a nonconforming use. Nothing contained in this division shall require any change in the construction, alteration, or intended use of any structure, the construction or alteration of which was begun prior to the effective date of the ordinance from which this section is derived, and is diligently prosecuted.
   B.   Marking and lighting. Notwithstanding the preceding provisions of this section, the owner of any existing nonconforming structure or tree is hereby required to permit the installation, operation, and maintenance thereon of such markers and lights as shall be deemed necessary by the Joint Airport Zoning Board to indicate to the operators of aircraft in the vicinity of the airport the presence of such airport obstructions. Such markers and lights shall be installed, operated, and maintained at the expense of the Purcell Municipal Airport and the City.
(Ord. No. 01-A14, § 6, 9-27-2001)