Piney Branch is a tributary of Rock Creek, a free-flowing tributary of the Potomac River, which empties into the Atlantic Ocean via the Chesapeake Bay in the United States. It runs along Piney Branch Parkway, and joins Rock Creek at Piney Branch and Beach Drive in the Northwest quadrant of Washington, D.C. The Piney Branch creek is an order 1 stream and the watershed has an area of approximately 1,236,500m2 or 0.48mi2.