This question is frequently asked by motorists involved in automobile accidents with livestock on a roadway, or by owners of private land in rural subdivisions whose ornamental plants are eaten by livestock from adjoining State Trust grazing land.
The answer is not easily found. The Arizona Department of Agriculture's Arizona Revised Statutes, Title 3, Article 8 (No-Fence Districts), contains nine separate statutes that comprise the open range laws of the State. A motorist who has been involved in an accident and wants to know if a particular location is "open range" should contact the County Board of Supervisors. The Board of Supervisors is the entity that has the authority to designate No-Fence Districts. If an area is not within a No-Fence District, it is open range. The Board of Supervisors keeps the records for such designations. (ARS 3-1421-1422)
The landowner who is concerned with livestock damaging plants and other private property, has an obligation to fence his/her private land with a lawful fence to keep animals out. Having a lawful fence is necessary in any action to recover damages due to trespassing animals. (ARS 3-1427)