Do you mean city level ? county , private ? state ? fed? etc. You need to be specific . But in general : Anywhere that there's no prohibitions saying "no metal detectors" .
To know that , just look up your city's or county's rules , which are perhaps on their website . Or in binder form on the front desk counter, etc... If you seen nothing that prohibits metal detecting, then Presto, it must not be prohibited.
Use a little common sense, of course . No shovels in the park , don't be in the middle of retrievals when lookie-lous are watching . Go at low traffic times and don't be waltzing over beach blankets , etc.....
