{"nrhp_refnum":"75000447","name":"Ott's Assay Office","other_names":["South Yuba Canal Office"],"category":"building","location":{"address":"130 Main St.","address_restricted":false,"city":"Nevada City","county":"Nevada County","state":"CA","lat":39.26306716100004,"lon":-121.01672457799998,"geom_source":"nps_gis"},"listed_date":"1975-04-14","is_nhl":false,"nhl_designated_date":null,"areas_of_significance":["Commerce","Engineering"],"significance_levels":["state"],"summary":{"what_it_is":"A pair of adjoining 1855 brick commercial buildings at 130 Main Street, Nevada City, California, built as the City Drug Store for Dr. John Lark and the South Yuba Canal Company building next door.","why_significant":"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.","narrative":"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.","period_of_significance":"19th Century; constructed 1855","architect_builder":null,"architectural_style":null,"criteria":[],"status_note":"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.","vacant_flag":true,"machine_generated":true,"model":"claude-sonnet-5-5","prompt_version":"v1.0-2026-10-29","generated_at":"2026-10-29 02:55:32.010314-05","source_pdf":"https://s3.amazonaws.com/NARAprodstorage/lz/electronic-records/rg-079/NPS_CA/75000447.pdf"},"photo":{"url_800":"https://nationalhistoricalregister.com/media/75000447/4f95665b32-800.webp","url_1600":"https://nationalhistoricalregister.com/media/75000447/4f95665b32-1600.webp","licence":"CC BY-SA 3.0","author":"Almonroth","credit_html":"<a href=\"https://commons.wikimedia.org/wiki/File:Ott%27s_Assay_Office-4.jpg\" rel=\"noopener\">Almonroth</a>, <a href=\"https://creativecommons.org/licenses/by-sa/3.0\" rel=\"license noopener\">CC BY-SA 3.0</a>, via Wikimedia Commons","source_page":"https://commons.wikimedia.org/wiki/File:Ott%27s_Assay_Office-4.jpg"},"district":{"nrhp_refnum":"85002520","name":"Nevada City Downtown Historic District","url":"https://nationalhistoricalregister.com/districts/california/nevada-city-downtown-historic-district-85002520/"},"sources":{"nps_snapshot_date":"2026-05-22","nara_catalog":"https://catalog.archives.gov/id/123860152","wikipedia":"https://en.wikipedia.org/wiki/Ott%27s_Assay_Office","wikidata":"https://www.wikidata.org/wiki/Q20709653"},"indexable":true,"url":"https://nationalhistoricalregister.com/california/nevada-county/otts-assay-office-75000447/"}