Accotink Creek begins where several small feeder creeks flow together in the middle portion of Fairfax County, near the City of Fairfax. For the few miles it flows east, it is sluggish. Where it turns south, it picks up speed until it reaches Lake Accotink. A man-made resevoir, Lake Accotink is the centerpiece of popular park by the same name, operated by the Fairfax County Park Authority. Below the dam of Lake Accotink, Accotink Creek flows more swiftly. The American Whitewater Affiliation rates the section below Telegraph Road as Class 2 - Class 3 rapids.

In much the same way the north half of the Fairfax Cross County Trail follows the Difficult Run Stream Valley, most of the FCCT south of Fairfax City follows the Accotink Creek Stream Valley. The trail passes by Lake Accotink in Lake Accotink Park, home of the annual cardboard boat regatta and the site of a 200 feet high railroad trestle.