Wolf Trap's stream is a type C low gradient stream with meandering alluvial channels and broad, well defined floodplains. Heavy rain and runoff from neighboring housing subdivisions greatly augments the volume of the stream flowing through the park. Wolf Trap Run flows to the north from the south-east point of entry into the park. Halfway through its run, in the north-east section of the park it is joined by the Old Courthouse Branch Creek which flows into Wolf Trap Run. From this point it redirects to the west and exits the park from the park's north-west boundary. Significant erosion of the stream bank has occurred in several distinct areas as a result of increased runoff and intermittent flooding. Several projects to plant riparian buffers to stabilize the creek banks have been completed, including placement of rip-rap along creek banks and tree planting in various locations. Erosion monitoring and control is an ongoing project within the park.