San Antonio Creek arises at on the southwest slopes of Mount Stakes and descends into the San Antonio Valley. San Antonio Creek's tributaries are, in order heading downstream, Beauregard Creek on the right, Jumpoff Creek on the left, and Long Gulch on the right. Its confluence with Arroyo Bayo forms the source of Arroyo Valle. Arroyo Valle proceeds through Lake Del Valle to join Arroyo de la Laguna thence to Alameda Creek and finally terminates in San Francisco Bay. San Antonio Creek and Beauregard Creek are ephemeral.