Interactive Maps

The Lower Potomac

The Potomac Estuary

Mount Vernon to Reagan Airport

Mall Area

Georgetown to Great Falls

Potomac Piedmont

Upper Potomac

The North Branch

Boat Ramps

Monitoring Sites

Bridges and Ferries

Cruises and Charters

Search Potomac Sites

McMahons Mill

Maryland Recreation Site

At Canal Mile 88 is a large private campground with campsites for recreational vehicles and tents. The site is located close to the Dam #4 boat ramp. A museum features artifacts from the civil war era.

Contact Information
McMahons Mill
7900 Avis Mill Road
Williamsport MD 21795
301-223-8778
Website