Idaho Code § 18-7017: Defacing natural scenic objects.

It shall be unlawful for any person to paint, sketch, or place in any manner or form or by any means, upon any rock or rocks or similar natural object or objects, any place within the state of Idaho, any sign, advertisement or picture or commercial or business name, for business or commercial purposes. Any person who violates the provisions of this section shall be deemed guilty of a misdemeanor.