Idaho Code § 43-2526
The board may provide for the publication of any resolution or other proceeding adopted by it pursuant to this code in the official newspaper of the district. For a period of thirty (30) days after such publication any person in interest shall have the right to contest the legality of such resolution or proceeding or any bonds which may be authorized thereby. No contest or proceeding to question the validity or legality of any resolution or proceeding, or any bonds which may be authorized thereby, passed or adopted under the provisions of this code shall be brought in any court by any person for any cause whatsoever, after the expiration of thirty (30) days from the date when the resolution or proceeding was published, and after such time the validity, legality and regularity of such resolution or proceeding or any bonds authorized thereby shall be conclusively presumed. If the question of validity of any bonds issued pursuant to this code is not raised within thirty (30) days from the date of publication of the resolution or proceeding issuing said bonds and fixing their terms, the authority to issue the bonds, the legality thereof and of the assessments necessary to pay the same shall be conclusively presumed and no court shall thereafter have authority to inquire into such matters.
Idaho Code § 43-2526