Ariz. Rev. Stat. § 48-2017
If the engineer's report required by this article recommends that sewer service or garbage disposal and treatment service for the sanitary district can be provided by a method other than construction of facilities by the district or the maintenance of an on-site sewage disposal management plan and the board of directors of the district desires to adopt such method and enter into a contract with another sanitary district, a municipality, other governmental subdivision or agency or a private entity for sewer service or garbage disposal and treatment service for the district, the board shall submit to the qualified electors of the district who are eligible to vote in bond elections the question of whether the district shall enter into such a contract for sewer service or garbage disposal and treatment service. The proposition of whether sewer service or garbage disposal and treatment service for the district shall be provided by contract may be submitted to the qualified electors of the district in a separate election called for that purpose or in conjunction with a bond election called pursuant to this article, or as an alternate proposition to the issuance of bonds by the district. Any election called pursuant to this section shall be called and held as provided in section 48-2020.
A.R.S. § 48-2017