Ariz. Rev. Stat. § 11-271
When the aggregate indebtedness of a county does not exceed six per cent of the value of the taxable property within the county as ascertained by the last property tax assessment, and the county has no suitable courthouse, jail or other county buildings, the board may erect them, and for that purpose and for purchasing the land for such buildings, may issue on behalf of the county bonds not exceeding in the aggregate an amount which, when added to the then existing indebtedness of the county, does not exceed six per cent of the value of the taxable property of the county. The board shall first adopt and enter a resolution of intention to issue the bonds and erect the building, stating the public need for the building, the estimated cost and the amount of the bonds to be issued.
A.R.S. § 11-271