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St. Helena's Bale Grist Mill wins award for historic restoration
Napa Valley History

St. Helena's Bale Grist Mill wins award for historic restoration

  • Updated

Rob Grassi, millwright at Bale Grist Mill State Historic Park in St. Helena, was recently awarded the 2020 Preservationist of the Year Award of Merit from Napa County Landmarks for his work restoring the Bale Grist Mill wheel using traditional methods and materials.

Grassi restored the wheel with the financial help of the Napa Valley State Parks Association, and with the assistance of Napa Open Space District staff members Tyler Beach and Jacob Cull. The Napa Open Space District is the operator of the Bale Grist Mill State Historic Park.

The waterwheel had not been fully restored since the 1980s. Though built of durable California redwood, which is highly rot-resistant, the amount of water on the wheel took its toll over the years. Some arms were replaced in 2014 with further restoration needed. Rob, Tyler and Jake began the recent restoration of the 36-foot waterwheel by fabricating and installing these additional arms themselves, completing this phase in January 2020.

As Rob and the Napa Open Space District team completed this work, millwright Ben Hassett was busy in Kentucky fabricating the waterwheel components including bucket shrouds, cover shrouds, bucket boards, sole planking boards, gear shrouds (inner and outer), and inner outer shrouds. All of the waterwheel components were shipped from Kentucky to California by March in rough lengths to be cut to fit for installation on site, except for the bucket and cover shrouds which Ben Hassett finished at his shop. Rob and his team utilized as many original fasteners as possible; only having to purchase around 130 new bolts.

According to Rob, “All fasteners were hot dipped galvanized. We were able to reinstall the original galvanized metal tires (the metal bands around the outside of the buckets). We began disassembly of the wheel in April beginning with the tires, all the sole planking, then all the buckets, then all bucket shrouds, and finally all cover shrouds. Then we began assembly of new materials in reverse beginning with the cover shrouds and ending with the tires. Work was always performed with the balance of the wheel in mind. When this portion of the restoration was completed, we focused our attention to replacing the gear shrouds. These were replaced by removing and replacing new two inner and one outer gear shroud section at a time and removing and re-hanging the associated sectional cast iron gearing. We worked our way around the wheel until completed. Then, lastly, we removed and installed new the inner outer shrouds. All materials used in the restoration were from California redwood.”

Given that this large of a project, especially one involving a particularly large waterwheel was accomplished primarily by Rob and two other staff members, rather than by a larger crew and involving heavy equipment, was a bright spot in an otherwise difficult year. COVID-19 shutdowns at the adjacent campground in Bothe-Napa Valley State Park afforded some extra time for the project, but the interruption of the Glass Fire, which almost reached the mill’s redwood water tank, and the fact that the work was completed among other work and projects at the parks, makes this accomplishment that much more laudable.

Rob and his team finished the entire waterwheel project by Dec. 1, clearing the way for the mill to once again host tours and school field trips once that is safely possible.

Thanks to the expertise of Rob Grassi and Ben Hassett, the staff of the Napa Open Space District, and the Napa Valley State Parks Association who paid for all that lumber, the Bale Grist Mill’s redwood wheel has a new lease on life, and the mill will continue its role as the historical gem of upper Napa Valley.

Learn more about the Historic Bale Grist Mill at



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