The purpose of the plan is to bring about coordinated physical development in accordance with the present and future needs of the county. The comprehensive plan shall be developed so as to conserve the natural resources of the county, to insure efficient expenditure of public funds, and to promote the health, safety, convenience, and general welfare of the public. Such comprehensive plan may include but not be limited to, among other things, studies and recommendations relative to the location, character and extent of highways, railroads, bus and other transportation routes, bicycle facilities, bridges, public buildings, public services, schools, parks, open space, housing quality, variety and affordability, parkways, hiking and riding trails, airports, forests, wildlife areas, dams, projects affecting conservation of natural resources, air quality, water quality and floodplain zoning.

Concern has been expressed that mesquite bosques are disappearing or diminishing in quality, and that the survival of the mesquite mouse is consequently threatened. This study, funded by a grant from the Arizona Heritage Fund to the Pima County Regional Flood Control District, investigated the current distribution of the mesquite mouse by reviewing historical records from museum specimens, examining existing potential habitat at historic locations of the species and elsewhere in the county, and conducting a live-trapping study at 19 sites representing a range of ecological communities with mesquite as a major component.