Mercury Mine Remediation Program


From the 1850's into the 1970's mercury deposits were mined in the upper Cache Creek and Putah Creek watersheds and processed to produce the elemental form known as “quicksilver.”  Mercury mined in this region was used during the Gold Rush throughout much of the Sierra Nevada to amalgamate and recover gold particles from ore and placer deposits.   More recently, mercury was mined during World War II for ammunitions and in the 1950-1970 period  when mercury was used in hearing aids.  

Regional Mercury Problems and Programs to Address Them

Most of the creeks and lakes in the Cache Creek and Putah Creek watersheds are "impaired" by mercury contamination. In waterways, elemental forms of mercury can be converted to methylmercury, a highly toxic and bioaccumulative form that is typically 10-million fold more concentrated in predatory fish than in the water. Eating contaminated fish can result in neurological damage particularly to fetuses during pregnancy and children. The current list of such water bodies is available HERE.

TMDLs (Total Maximum Daily Loads) are regulatory control plans have been developed already for Clear Lake and for the Cache Creek watershed below Clear Lake. Documents regarding these regulatory programs are available HERE.


CLICK HERE to join the listserve for this specific program. Note: the link at the bottom of the webpage is for Tuleyome's email blast, not for information on this program.


Project overview

Tuleyome is implementing in 2016-2018 a $2.4 million dollar grant by the California Department of Fish and Wildlife's Ecosystem Restoration Program (ERP) to address drainage waters from the Corona and Twin Peaks Mines in northwest Napa County. Additional, related work is being funded by the Corona/Twin Peaks Historical Assoc., LLC, and the Napa County Regional Park and Open Space District.  This page and its attachments contains information about the project.  CLICK HERE for more information about the Corona and Twin Peaks mines.

Project goals are to (1) render the project site safe for public use; and (2) support healthy aquatic ecosystems downstream in James Creek, Pope Creek, Lake Berryessa, lower Putah Creek, lower Yolo Bypass, and the Delta.

Project objectives are to (1) improve the effectiveness of existing mine drainage treatment systems for the Boiler House and Twin Peaks entrances [referred to as “adits”]; (2) minimize leaching and mobilization of nickel and acid drainage from the mined ore body through the Corona Drain Tunnel; and (3) address physical and chemical hazards on the site.

CLICK HERE to view a brief presentation about the project.

CDFW logo
ERP logo

Contact Information

Bret Hewitt, Project Lead
Phone: 530-750-9234

Stephen McCord, Project Manager
Phone: 530-220-3165