Plum Run (Chartiers Run tributary)Plum Run is a long 2nd order tributary to Chartiers Run in Washington County, Pennsylvania.CoursePlum Run rises about 2 miles southwest of Venice, Pennsylvania, and then flows southeast to join Chartiers Run at Houston.WatershedPlum Run drains of area, receives about 39.2 in/year of precipitation, has a wetness index of 324.74, and is about 45% forested.