The acknowledgment and recording of such plat is equivalent to a deed in fee simple of such portion of the premises platted as is on such plat set apart for public streets or other public use, or as is thereon dedicated to charitable, religious or educational purposes; provided, however, that in a county where a highway district exists and is in operation no such plat shall be accepted for recording by the county recorder unless the acceptance of said plat by the commissioners of the highway district is endorsed thereon in writing.
Idaho Code § 50-1312