Idaho Code § 50-3119
Any person in interest who feels aggrieved by the final decision of a governing body or a district board in the formation or governing of a district, including, with respect to any tax levy, special assessment or bond, may, within sixty (60) days after such final decision, seek judicial review by filing a written notice of appeal with the clerk of the district and with the clerk of the district court for the judicial district in which a majority of the land area of the district is located. After said sixty (60) day period has run, no one shall have any cause or right of action to contest the legality, formality or regularity of said decision for any reason whatsoever and, thereafter, said decision shall be considered valid and uncontestable and the validity, legality and regularity of any such decision shall be conclusively presumed. With regard to the foregoing, if the question of validity of any bonds issued pursuant to this chapter is not raised on appeal as aforesaid, the authority to issue the bonds, the legality thereof and of the levies or assessments necessary to pay the same shall be conclusively presumed and no court shall thereafter have authority to inquire into such matters.
Idaho Code § 50-3119