Stewart Run is a tributary of the West Branch Octoraro Creek in Lancaster County, Pennsylvania, in the United States.
It turns southwest and receives another tributary from the left before its confluence with West Branch Octoraro Creek.
[1] Stewart Run joins the West Branch Octoraro Creek 6.15 miles (9.90 km) upriver of its mouth.
[3] The Theodore A. Parker III Natural Area, a 100-acre park named after the famed ornithologist, is adjacent to the creek.
Stewart Run supports flora including trout lilies, violets, mayapple, club mosses, ground pine, ferns and lichens.