Idaho Code § 70-1201

The powers of the port district shall be exercised through a port commission consisting of three (3) members, one (1) from each of the three (3) county commissioner districts of the county in which the port district is located, when the boundaries of the port district are co-extensive with the boundaries of such county. When the port district comprises only a portion of a county, three (3) commissioner districts, numbered consecutively, having approximately equal population and with boundaries following county precinct lines, shall be described in the petition for the formation of the port district, and one (1) commissioner shall be elected from each of said commissioner districts. Any port district may, after formation, be redistricted in the original county of formation as in this act provided.