This California state park is the site of a water-powered grist mill that was built in 1846. It was once the center of social activity as Napa Valley settlers gathered to have their corn and wheat ground into meal or flour. The owner of the mill was Dr. Edward Turner Bale. He received the property in a land grant from the Mexican government and lived near the site until his death in 1849. The mill remained in use until the early 1900s.

The mill and its 36-foot water wheel are protected as a state historic landmark and have been partially restored. A trail connects the historic park to Bothe-Napa Valley State Park. Additionally, the park includes the site of the first church in the Napa Valley as well as the Pioneer Cemetery.