sentences:  The headwaters of the creek are located about northeast of Aldie.The creek flows eastward near Arcola and continues generally northeast to its mouth at the Potomac near the southern end of Seldon's Island to the north of Sterling and about southeast of Leesburg.The watershed of the creek is 67.5 mi2 (175 km2) in Loudoun and 23.8 mi2 (62 km2) in Fairfax.