Mohawk Mine Brownfields Remediation

Mohawk Mine Background & Risk

The Mohawk Mine, also known as the Chilcoot-El Dorado-Mohawk Mine, is a former copper mine, abandoned after it last operated in the 1930s. The Feather River Land Trust (FRLT) acquired the Spring Creek Ranch, which contains the mine, in 2021. Surface water and sediment in Spring Creek, which flows past the former mine and remnant waste rock piles, and soil on and around the mine waste, have been assessed to determine if contaminants are present on-site. Environmental site assessments have indicated elevated levels of metals in soil, sediment, and surface water, and a potential for acid mine drainage (AMD), presenting a risk of copper leaching from the mine waste rock into adjacent waterways.

Next Steps to Clean Up Mohawk Mine

FRLT plans to transfer the Spring Creek property to the Plumas National Forest Service for recreational use. Prior to doing so, cleanup efforts must be conducted to eliminate human and ecological health risks from metal contamination and AMD. In collaboration with FRLT, Sierra Institute will be working to conduct further sampling and analysis at the site to better refine cleanup objectives prior to the development of a cleanup plan. A public meeting was held in early January 2026 to engage with community members regarding the site, review the completed environmental assessments, and determine next steps moving forward. The Sierra Institute team fielded questions about planning and implementing the cleanup.

More on Sierra Institute’s Rural Brownfields Program

A brownfield is a site undergoing redevelopment or reuse that is complicated by the presence of hazardous substances, pollutants, or contaminants. Sierra Institute’s North State Rural Brownfields Program works to perform assessments and initiate remediation efforts to support the redevelopment of brownfields throughout California’s North State. With funding from the U.S. Environmental Protection Agency, project sites include abandoned mines, sawmills, and agricultural sites. Ultimately, this work supports improved environmental and public health, economic development, and long-term resilience in rural communities.