Ott's Assay Office
Also known as: South Yuba Canal Office
Why it's listed
Two adjoining brick buildings at 130 Main Street in Nevada City date to 1855 and are documented as the oldest business buildings remaining in the town. One was built for Dr. John Lark as the City Drug Store and later housed Ott's Assay Office. The other became the office of the South Yuba Canal Company. In 1859 assayer James J. Ott tested ore brought from the Washoe country, and press coverage of the result helped trigger the Washoe Rush and the development of the Comstock Lode. Ott's business operated for almost a century, closing in 1955 under his son Emil. The canal company's ditch system dated to 1850 and grew into the largest ditch operation in the state, and it is part of the corporate lineage of P. G. & E. In the 1960s the California Division of Highways redesigned a planned freeway, at an estimated cost of $235,000, to save the buildings. The canal building was also registered as a state historical landmark.
Significance in brief: The buildings are documented as the oldest business buildings in Nevada City. James J. Ott's assay of Washoe ore in 1859 helped set off the Washoe Rush and the development of the Comstock Lode. The South Yuba Canal Company, headquartered next door, held some of California's earliest mining ditches and was a forerunner of P. G. & E.
Machine-generated summary. This summary was generated by a language model from the official nomination document and has not been reviewed line by line by an editor. It may contain errors. Check the source document before relying on any detail. Source: nomination document (PDF) · National Archives catalog entry. NRHP reference 75000447, listed April 14, 1975. Summary generated October 2026 (model claude-sonnet-5-5, prompt v1.0-2026-10-29, confidence medium).
Key facts
| Address | 130 Main St., Nevada City |
|---|---|
| County | Nevada County |
| Listed | April 14, 1975 |
| Reference number | 75000447 |
| Resource type | Building |
| Period of significance | 19th Century; constructed 1855 |
| Areas of significance | Commerce, Engineering |
| Level of significance | State |
| Status (as stated in the nomination) | Owned by the City of Nevada City. The South Yuba Canal building has been restored, while the Assay Office building was described as deteriorated and awaiting restoration. Marked as unoccupied. |
| Acreage | 0.1 |
| Within district | Nevada City Downtown Historic District |
| Coordinates | 39.26307, -121.01672 (NPS GIS) |
What listing means for this property
For an income-producing building, listing (individually or as a contributing building in a district) is the gateway to the 20% federal rehabilitation tax credit on qualified rehabilitation costs, often stackable with state credits. Work claiming the credit must follow the Secretary of the Interior's Standards and be approved in advance.
Listing does not restrict a private owner acting without federal money or permits; where federal funding or licensing is involved, Section 106 review applies.
Noted as vacant in the nomination. Nomination documents can be decades old; current status may differ. If you are considering buying an empty listed property, read the due-diligence checklist.
General information, not legal or tax advice. Rules change; confirm with your State Historic Preservation Office or a qualified adviser.
Sources and further reading
- National Park Service, National Register of Historic Places database (snapshot May 2026), reference 75000447.
- Nomination form (PDF, National Archives) — catalog entry
- Wikipedia article (used for cross-checking only; text not reproduced here)
- Wikidata Q20709653
- This listing as JSON
Last updated October 2026. Found an error? See the editorial policy for how to report it.