Ariz. Rev. Stat. § 12-818
If the attorney general, a county attorney or a city attorney receives a petition alleging the existence of a nuisance subject to the provisions of this article and determines that there are reasonable grounds to believe that such a nuisance exists, an action to abate such nuisance shall be brought forthwith. Such petition may be signed by only persons who operate commercial enterprises within a one-half mile radius of the location of the alleged nuisance or who are qualified electors whose voting address is within a one-half mile radius of the location of the alleged nuisance. Such petition must be signed by at least one hundred of the persons eligible to sign or fifty per cent of the persons eligible to sign, whichever is greater.
A.R.S. § 12-818