Argonaut Mine

Overview

Argonaut Mine is a historic hard rock gold mine that operated from the 1850s to 1942 in Jackson, California. It was added to the EPA's National Priorities List (NPL) in September 2016. The site sits in an active cleanup phase, with investigations still ongoing and a final remedy not yet selected.

The main contaminants are arsenic, lead, and mercury, all left behind by past mining and gold extraction. These metals show up in soil, surface water, groundwater, and mine tailings. Tailings are the leftover rock and waste from ore processing. Contaminated areas include the main tailings zone behind a concrete arch dam, land near the mine headframe at the end of Spunn Road, and a northern tailings area between Highway 49/88 and Stark Lane. EPA's performance measures confirm that human exposure is not currently under control, meaning unsafe contamination levels exist and people could come into contact with them.

EPA has completed several cleanup actions since 2014. Workers removed contaminated soil from residential yards near Argonaut Lane and Pioneer Street, replaced soil near the lunch area at Jackson Junior High School, and covered an exposed slope with concrete. Between 2022 and 2023, EPA removed 120,000 cubic yards of contaminated tailings, soil, bedrock, and processing waste from both sides of Argonaut Lane, relocating it to an existing waste area behind the courthouse. That cleared area has since been replanted with grass and native oak trees. This work received funding from the Bipartisan Infrastructure Law, which directed $3.5 billion to Superfund cleanups nationwide. An additional removal action started in June 2024 with completion targeted between November 2027 and January 2028.

EPA is now preparing for residential yard cleanup at 40 properties, with work expected to start in spring 2026. The agency recently completed a public comment period on an Engineering Evaluation and Cost Analysis (EECA) that outlines cleanup options for those residential areas. Sampling of groundwater, surface water, and soil is still underway in the main tailings area and near the mine headframe on both sides of Highway 49.

Community members can review site documents and engineering drawings at the Amador County Main Branch Library, 530 Sutter Street, Jackson, CA 95642, phone (209) 223-6400. EPA has also prepared a Community Involvement Plan to guide communication throughout the cleanup. For questions, residents can contact the EPA Community Involvement Coordinator or Remedial Project Manager directly. Questions about work on Sutter Street or past dam buttressing should go to the California Department of Toxic Substances Control (DTSC).