Pacheco was briefly a prosperous commercial center. During this period, Pacheco Slough was deep enough to receive ocean-based shipping. From 1851 to nearly 1873, Pacheco was the county’s commercial center: the shipping port for the grain grown in the Ygnacio, San Ramon and Tassajara valleys, with warehouses, a flour mill and shops along the creek. Walnut Creek, (then known as Pacheco Creek), then flowed deep and free into Suisun Bay. For over 20 years, Pacheco was a major shipping port for central Contra Costa County.