In Arizona, a county may exercise its powers "only by the board of supervisors" or by its agents or officers, where permitted by law, acting pursuant to the board's authority. A.R.S. 11-201(A); see also A.R.S. 11-202(A) (county has powers provided by state law and those implied therefrom). The board's statutory powers and duties include the authority to adopt, amend, and repeal county ordinances that are necessary to carry out the duties, responsibilities, and functions of the county, 11-251.05(A)(1), and to "make such contracts . . . as may be necessary to the exercise of its powers," 11-201(A)(3). Arizona statutes also name certain "county officers" and describe their powers and duties, but the office of county administrator is not among those enumerated. See A.R.S. 11-401 through 11-600.