Arroyo Seco is an  watercourse in Alameda County, California, that traverses through the city of Livermore, emptying into Arroyo Las Positas. Arroyo Seco means "dry stream" in Spanish. Arroyo Seco lies above the Arroyo Seco watershed, which includes the eastern part of the city of Livermore and also the Sandia National Laboratory.
In the context of Alameda County, California, Arroyo Seco is a watercourse that traverses through the city of Livermore, ultimately emptying into Arroyo Las Positas. Its name reflects its tendency to be dry during certain periods.