Before Napa Valley was wine country, it was grain country, and the place to grind your grain was a mill on Mill Creek just north of St. Helena.
The history
Edward Turner Bale and Maria Sobranes Vallejo Bale built the water-powered grist mill in 1846, according to California State Parks. It sat on Bale's Rancho Carne Humana land grant and was built from local Douglas fir and coast redwood on a native stone foundation. A ditch and wooden flume carried water from a millpond to the top of the waterwheel. The first wheel wasn't strong enough in dry summers, so it was replaced with a bigger one like the 36-foot wheel there today. Wikipedia calls it one of only two water-driven mills left west of the Mississippi.
The mill was a social center, too, where settlers gathered while their corn and wheat were ground into meal and flour. It ran until 1879. The Native Sons of the Golden West later took over the property and restored the mill in the late 1960s and early 1970s, led by Bismarck Bruck, a grandson of Dr. Bale.
Visiting
The park is about three miles north of St. Helena on Highway 29. It's open on weekends and some Monday holidays from 10 a.m. to 4 p.m., with the last tour starting at 3 p.m. Vehicle day use is $10. Napa County Regional Park and Open Space District runs it, and a trail connects it to Bothe-Napa Valley State Park. The next listed event is Old Mill Holidays on Dec. 5.