Boat Ramps in District of Columbia

Washington D.C. sits at the confluence of the Potomac and Anacostia rivers, and while it's not a state, it has legitimate public boat ramp access that serves both residents and visitors coming in from Maryland and Virginia.
The Potomac through D.C. is tidal water, wide and navigable by most recreational vessels. Upstream toward Great Falls the river changes character dramatically and becomes dangerous whitewater that is not suitable for powerboats. Stay below the fall line and you're on manageable water. The Anacostia on the eastern side of the city has improved significantly in water quality over the past two decades and has ramp access along its D.C. reach for smaller boats.
The broader metro area gives D.C. boaters easy access to some of the best Chesapeake Bay tributaries in the region by crossing into Maryland or Virginia, and most serious boaters in the area treat the surrounding states as their extended backyard. Striped bass fishing on the tidal Potomac has a strong local following and the fish run through D.C. water as readily as anywhere else on the river.
Registration and boating regulations in D.C. fall under the Metropolitan Police Department Harbor Patrol rather than a state wildlife agency, which is worth knowing if you have a question about local rules or need assistance on the water.