Idaho Code § 67-4116: Marking and maintenance.

The Idaho State Historical Society shall provide signs or markers for Idaho state historic sites. Said markers, if located upon land owned by the state of Idaho, shall be maintained by the department of the state having charge of the administration of said land. If located upon private land, said markers shall be maintained by agreement or arrangement between the Idaho State Historical Society and any local historical organization where said historic site is located or, and with the consent of, the landowner.