Ariz. Rev. Stat. § 48-4461
A. The board of directors shall:
4. Determine the boundaries of the divisions in the district that shall be numbered respectively divisions one, two, three, four, five and six. After each United States decennial census the board shall define the boundaries and limits of each division and shall:
8. Require that all monies received on behalf of the district be deposited in such funds as may be established by the district to be spent at the direction of the board as provided by this chapter. Monies that are not required immediately may be invested for periods of not more than five years in any of the following, unless otherwise provided: