620 ILCS 25/25

In granting any permit under Section 23 or variance under Section 24, the Department or any administrative agency or Board of Appeals may, if it deems such action advisable to effectuate the purposes of this Act and reasonable in the circumstances, so condition such permit or variance as to require the owner of the structure or tree in question to permit the State or the political subdivision, as the case may be, at its own expense, to install, operate, and maintain thereon such markers and lights as may be necessary to indicate to flyers the presence of an airport hazard.