Idaho Code § 40-1106
Nothing in this chapter shall be construed as a limitation of the power of the commissioners to issue bonds for the construction or the repairs of highways and bridges. Whenever the commissioners shall issue bonds for the construction or repair of highways and bridges under the provisions of chapter 19, title 31, Idaho Code, upon the authorization of two-thirds (2/3) of the qualified electors of the county voting at an election held for that purpose, pursuant to a resolution of the commissioners and entered upon their journal specifying, describing and defining the highways or bridges to be constructed or repaired, and giving the termini and the general course of each highway and the approximate location of each bridge it is proposed to construct, and appropriating a specific amount for any highway or bridge wholly or partially within any organized highway district, then the commissioners shall have full jurisdiction and power to locate and construct or repair the highway or bridge within the highway district, and to apply a specific appropriation so derived from the issue of bonds or so much of them as may be necessary.
Idaho Code § 40-1106