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Recovery Act Project Activity

Iron Mountain Mine
Redding, CA

The Stimulus money will allow acceleration of the dredging, treatment and disposal of heavy-metal contaminated sediment located in the Spring Creek Arm of the Keswick Reservoir -- taking approximately 18 months to complete rather than three years.  The EPA will construct pipelines and pump stations to move contaminated sediment from the Spring Creek Arm of Keswick Reservoir  to a disposal cell scheduled to begin construction in May 2009.  Manufacturing contractors will start building treatment systems and sediment pumps in April for on-site installation in late summer.  Hydraulic dredging is scheduled to begin in October after the disposal cell is constructed, and the pipelines, pumps and treatment facilities are installed.

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Iron Mountain Mine was mined for iron, silver, gold, copper, zinc and pyrite from the 1860s through 1963. As a result of the mining activities, annual rains sent toxic levels of copper, cadmium and zinc from the mine into the Sacramento River -- a valuable commercial fishery and a major source of drinking water for more than 70,000 people in northern California. The Sacramento River is designated as critical habitat for the endangered Winter Run Chinook Salmon and several threatened anadromous fish populations.

The EPA’s cleanup actions over the past 26 years include, construction in 1994 of a wastewater treatment plant to treat acid mine drainage from the underground mines, and the 2004 completion of the Slickrock Creek Retention Reservoir to control widespread contamination in the Slickrock Creek watershed.  The agency’s actions now prevent more than 98 percent of all metals in the acid mine drainage from entering the environment. 

Prior to the EPA’s actions, high levels of contaminants in the acid mine drainage mixed with higher-pH water within the Spring Creek Arm of Keswick Reservoir, resulting in precipitation and deposition of large amounts of heavy-metal laden sediment within the arm.  These contaminated sediments are susceptible to erosion and can be mobilized and carried downstream during severe storm events.  With 98 percent control of heavy-metal discharge, the EPA is able to dredge contaminated sediment from areas susceptible to erosion to eliminate threats to downstream resources.   Removing these contaminated sediments will also allow the Central Valley Project to produce $3 to $6 million of additional peak power by removing operational constraints that are currently needed on its hydropower facilities at Shasta Dam and the Spring Creek Power House to prevent contaminated sediment releases.


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