'This article is about a geographical area of Monterey County, California. For the stream in Sonoma County, see Arroyo Seco Creek.

Arroyo Seco is a watercourse in Alameda County, California which traverses through the city of Livermore. Arroyo Seco means dry stream in Spanish. The Arroyo Seco watershed include the eastern part of the city of Livermore and also the Lawrence Livermore National Laboratory.