Any permit or variance granted may, if such action is deemed advisable to effectuate the purpose of this chapter and be reasonable in the circumstances, be so conditioned as to require the owner of the structure or tree in question to install, operate, and maintain, at the owner's expense, such markings and lights as may be necessary. If deemed proper by the board of adjustment, this condition may be modified to require the owner to permit Lincoln County, at its own expense, to install, operate, and maintain the necessary markings and lights. (1983 Code § 18.80.110)