News Release

T – 15 – 15
Barbara A. Lee, Director

November 3, 2015

Contact: Jorge Moreno
(916) 869-5422

DTSC to build a storm water diversion system at a 99-year-old dam
site to protect Jackson

SACRAMENTO – With the rainy season approaching, the Department of Toxic Substances Control (DTSC) is initiating steps to build a storm water diversion system to help protect the City of Jackson from the danger posed by a dilapidated dam at the Argonaut Mine Tailings Site (Site).

DTSC is designing and building a system to divert storm water around the 99-year-old dam this winter to reduce the risk of a dam failure that could come from excessive pressure building up in the rain-soaked soil and mine tailings behind the dam. A study earlier this year found the dam to be structurally unstable.

“There is a very serious danger to the City of Jackson if this dam collapses,” said Charlie Ridenour, Supervising Hazardous Substance Engineer for DTSC. “We are working swiftly to help reduce the chances of a possible catastrophe.”

The storm water diversion system will involve creating an embankment 60 feet above the dam to capture storm water, which then will be redirected around the ends of the dam by pumps and pipes. A new culvert will be constructed under Argonaut Drive, which passes in front of the dam, to prevent water from ponding between the dam and Argonaut Drive. The expected completion date is November 23.

The Eastwood Multiple Arch Dam holds back more than 165,000 cubic yards of contaminated mine tailings and soil left behind from years of mining operations. The tailings contain dangerous levels of arsenic, lead and mercury. Since the mine closed in 1942, the privately owned dam has been neglected.

The U.S. Environmental Protection Agency (US EPA) is evaluating the Site for eligibility on the Superfund National Priorities List. US EPA has already completed cleanups of tailings contamination in several residential yards near the Site. A study completed this year by the U.S Army Corps of Engineers (USACE) and US EPA found that the dam is structurally unstable and that a dam failure could cause more than $100 million in economic damages.

DTSC is working with US EPA and USACE on design for a retrofit of the dam that will provide a long-term solution. However, because construction of the retrofit cannot occur before this year’s rainy season, DTSC’s storm water diversion system is being constructed to protect the community until the retrofit construction is complete.

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FOR GENERAL INQUIRIES: Contact the Department of Toxic Substances Control by phone at (800) 728-6942 or visit To report illegal handling, discharge, or disposal of hazardous waste, call the Waste Alert Hotline at (800) 698-6942.

The mission of DTSC is to protect California’s people and environment from harmful effects of toxic substances by restoring contaminated properties, enforcing hazardous waste law, reducing hazardous waste generation, and encouraging the manufacture of chemically safer products.