That portion of the middle fork of the Vermilion River which flows through land owned by the State of Illinois and the Vermilion County Conservation District within Vermilion County, Illinois, is hereby designated as a permanently protected river of the State of Illinois. The designated portion shall only include property for which the State of Illinois or the Vermilion County Conservation District holds title or a properly executed easement and which is contiguous to the middle fork of the Vermilion River. By agreement of the State Administrator and the owners of such property, such land is to be permanently protected pursuant to a plan adopted by the State Administrator.