Bale Grist Mill State Historic Park, State historic park in Napa County, United States

Bale Grist Mill State Historic Park is a state historic park in Napa County, United States, centered on a water-powered grist mill from the 19th century. The park includes the mill building, a millpond, and a wooded area with trails that show how the mill operated.

The mill was built in the 1840s to serve the growing settlement of Napa Valley. It operated for several decades before falling into disrepair, and later became a state historic park to protect its remains.

The mill is still used for demonstrations, where grain is ground into flour using the original stones. Visitors can watch the process and buy the flour, which connects the past to daily life today.

The park is open for walks, but the mill itself can only be visited during guided tours or special events. The paths are uneven in places, so wear comfortable shoes and allow about an hour to see the main sites.

The mill's water wheel is one of the few original wheels still in operation in California. The millpond that feeds it is fed by a stream that runs through the park, and the water flow is controlled to keep the wheel turning during demonstrations.