Resource Protection Areas Maps and Regulations
Fairfax County: Find your borders in relationship to the nearest park and Resource Protection Areas on this map. Note: when entering your address, don't include the word "street" or "drive" or whatever. For example, enter 21 Main, not 21 Main Street.
Loudoun: Go to Weblogis - Online Mapping System, click on Environment then also on Hydric Areas.
Arlington: Go to the Watershed and Resource Protection Areas map. Learn more here and here. Permits are not needed to remove invasive vegetation from RPAs in Arlington except for trees over 3 inches in diameter (assuming you are not causing soil disburbance.)