Dont know anything particular about the area where your going but generally:
Note: Most cities in Arizona require a city permit to metal detect in that city's parks. Please check with city authorities to see if a permit is required.
A no-charge Tucson metal detecting permit can be obtained at the Tucson Parks & Recreation Department offices:
Northwest District Office - 900 South Randolph Way 791-4873
Southwest District Office - 4208 South Santa Rita 791-5950
East District Office - 8257 East Broadway 791-5930
Oro Valley
Oro Valley Parks and Recreation requires a permit to metal detect in their three (3) parks. Call 229-5050 and request an application. Fill out the application, send it back. They will "validate" your application and send it back.
Marana
Marana Parks and Recreation does not require permits. They require that holes be filled and request that trash be removed. If you have questions call 682-3324.
Tucson Prohibited Areas
No metal detecting is allowed at Tucson's Fort Lowell Park and El Presidio Plaza. Additionally, no metal detecting is allowed in the immediate downtown Courthouse area.
Pima County
Currently, Pima County does not issue metal detecting permits for its parks and no metal detecting is allowed on any Pima County property.
Local Schools
Some local schools will allow metal detecting if permission is requested, check with each school. It is best to get written permission or have someone with authority sign a written permission statement you create.
Local Arizona State Parks
Arizona State parks can be metal detected after checking with the Park Ranger about any restricted areas.
Local National Parks
No metal detecting is allowed on National Parks.