[1] There are three bands of Bay Miwok Native Americans associated with early Walnut Creek, the stream for which the city of Walnut Creek is named:[6][7] the Saclan, whose territory extended through the hills east of present-day Oakland, Rossmoor, Lafayette, Moraga and Walnut Creek; the Volvon (also spelled Bolbon, Wolwon and Zuicun) near Mt.

Today's Walnut Creek is located within the earlier site of four Mexican land grants.

The grant was called Rancho Arroyo de Las Nueces y Bolbones, named after the principal waterway, Arroyo de Las Nueces (Walnut Creek), as well as for the local group of indigenous Americans (Bolbones).

[9] While the mainstem Walnut Creek flows through densely urbanized areas, the upper watersheds of its tributaries generally remain undeveloped open space.

Pine Creek drains the west slopes of flows through Mount Diablo State Park, Diablo Foothills Regional Park, and Castle Rock Regional Recreational Area.

From that confluence, Pacheco Creek flows north 4 miles (6.4 kilometers) through the Concord Marsh into Suisun Bay.

[10] This is consistent with archeological records of both Chinook and coho salmon (Oncorhynchus kisutch) at CCO-309, a site dating to 1400-1500 C.E.