I have metal detected several times in FFX county. I have only been told to leave once, at burke lake park, because I was "removing resources that belonged to the park"... a whopping 4 cents.
Another time I was in a neighborhood near downtown FFX, it was public property, a small little field and play ground. I had some old guy pull up in his PT cruiser and stare at me for about 45 minutes. He was on the phone the whole time, talked to a homeowner across the street, read the rules on the sign, followed me around, then left...
I have emailed Fairfax and here is their response:
"The first and most obvious route would be to look for signage. Our property is generally marked.
The second would be to use the Tax Administration website to determine property ownership. Once you determined who owns that land it would be your responsibility get permission from the property owner to ascertain what you can and can't do on that property. Here is the appropriate website: : http://icare.fairfaxcounty.gov/searc...x?mode=address
You can also contact the Park Authority at 703-324-8700 and ask for assistance. Our regulations are in place to protect our natural and cultural resources and therefore restrict the use or possession of tools which could be used to damage those resources.
In addition, the regulations were jointly adopted by the Fairfax County Park Authority and the Northern Virginia Regional Park Authority. So the restrictions under the regulations apply on all parkland owned by the two agencies.
If you need to contact the Northern Virginia Regional Park Authority you can do so at 703-352-5900.
SO my take is...
if it is a regulated PARK.. like Burke Lake (they charge money to non-ffx residents, and have a shop and putt putt etc etc..) then you should not metal detect. Any kind of regulated/maintained park, with the brown signs, you should be careful and probably avoid. If you go, READ THE SIGNS READ THE SIGNS READ THE SIGNS... that way you can say you had no way of knowing without going out of your way to find out. (which frankly, we are expected to do anyways..) If anyone asks you to leave; park ranger, police officer, citizen, it's usually a good idea to just go.
Now according to their responses, it his difficult to know for sure what kind of land will be park regulated, or to what degree. They make it sound like any land in FFX county is illegal to metal detect on... but then they put emphasis on PARKS... I asked how to tell if its a park of which the rules would apply to, and they said to look for signs.
I originally looked at the PDF on this page: http://www.fairfaxcounty.gov/parks/rules/
The section about metal detecting again, refers to parks... I also saw somewhere that having ANY tool is not allowed, including shovels.
I hope that helps.