Leader: Stephanie Mason The Mason Neck National Wildlife Refuge near Woodbridge, VA sits on the banks of the Potomac where it protects mature hardwood forest, nearly six miles of shoreline, and the largest freshwater marsh in Northern Virginia. It is one of our leader's favorite local parks and fall is an excellent time for a visit. Explorations on foot will follow the Woodmarsh Trail (natural surface with some mild uphill/downhill) and the Great Marsh Trail which is paved. Distance covered will range from 2.5 to 4 miles, depending on weather, sightings, and size of the group.