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.
Arroyo Seco is a waterway in Alameda County, California, that flows through Livermore and merges with Arroyo Las Positas. The term "Arroyo Seco" refers to a dry or intermittent stream.