Idaho Code § 40-1706
In areas where more than one (1) highway district exists and the highway districts were organized under the provisions of this chapter, the commissioners shall have the duty and obligation from time to time as shall be practical and for the best interests of the countywide administration of the secondary highway systems, to adjust the borders of the highway districts coexisting in the county as shall most equitably and economically permit the administration, operation and construction of the secondary highway system within the county. Notice of a proposal to change the boundaries of the highway districts within the county shall be given by the commissioners through the county clerk to the districts affected and notice shall be published in accordance with the provisions of section 40-206, Idaho Code. At the hearing any person objecting may be heard in opposition, and upon the closing of the hearing, the commissioners shall within ten (10) days after the hearing, notify the districts affected of their decision, and any district aggrieved by the decision shall have the right through its highway commissioners to appeal the decision directly to the district court of the county in which the district lies. Matters referred to the district court on appeal shall be submitted by petition for hearing within twenty (20) days of the announcement of the decision of the commissioners and the matter disposed of by the district court by reversal or approval. Failure to diligently prosecute the matter before the district court shall justify the district court in dismissing the appeal without hearing.
Idaho Code § 40-1706