Ariz. Rev. Stat. § 48-2467
For the purpose of this article, the board of directors of any district by affirmative vote of a majority of its members is authorized to adopt a resolution relating to the exercise of the powers granted by this article and to any other matters necessary to effectuate the full intent and purpose of this article. In the discretion of the board of directors, any bond issued pursuant to this article may also be secured by a trust agreement by and between the district and one or more corporate trustees or fiscal agents, which may be any trust company or bank having the powers of a trust company within or without this state. Any such resolution adopted shall be effective upon its adoption unless otherwise specified therein. Written notice of any meeting of the board for the purpose of taking action under this section shall be sent to all members of the board by certified or registered mail at least ten days prior to the date of such meeting.
A.R.S. § 48-2467