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U.S. EPA, California and Shasta County officials celebrate the completion of the Slickrock Creek Retention Reservoir

Release Date: 5/6/2004
Contact Information: Mark Merchant, (415) 947-4297

Recently completed facility at the Iron Mountain Mine Superfund site cuts overall mine contamination discharge to the Sacramento River by 95 percent

REDDING, Calif. -- In a ceremony today at the Iron Mountain Mine Superfund site in southwest Shasta County, U.S. Environmental Protection Agency officials celebrated the completion of the Slickrock Creek Retention Reservoir, which will cut the amount of pollutants flowing to the Sacramento River by 95 percent from historic levels.

"It took local, state and federal efforts to contain this mountain," said Wayne Nastri, administrator of the U.S. EPA's Pacific Southwest regional office. "Our team can now properly manage the remaining discharges from this mine because this dam will capture 95 percent of the toxic load, thereby protecting the Sacramento River and fishery."

When the U.S. EPA put the mine on the site on the Superfund list in 1983, acid mine drainage containing more than one ton of toxic metals were being released into the environment every day from the defunct 4,400-acre open pit and underground copper mine that operated between 1860 and 1962.

The Iron Mountain Mine discharge was a significant cause of the decline of the Sacramento River salmon and steelhead fishery.

Today this fishery is on its way to recovery due to the success of the U.S. EPA's efforts at Iron Mountain Mine, and the efforts of many other state and federal agencies to rejuvenate the most important salmon spawning grounds in California. In addition, the river is the major source of clean drinking water for more than 70,000 people in northern California.

In 1994, the U.S. EPA oversaw the completion of a wastewater treatment plant that prevented significant amounts of metals in the contaminated mine waters from flowing into the river system. Since then, the plant has treated more than 1.3 billion gallons of acid mine drainage, which translates to an 80 percent reduction of the copper and 90 percent reduction of the zinc discharged into the environment through 2003. The water treatment plant itself has kept approximately 1.9 million pounds of copper and 6.6 million pounds of zinc out of the environment.

With the completion of the Slickrock Creek Retention Reservoir, more than 95 percent of all of the metals in the acid mine drainage will no longer enter the environment, providing significant additional protection to these important spawning grounds and the Sacramento River ecosystem.

Iron Mountain Mine Site was mined for iron, silver, gold, copper, zinc and pyrite. The property includes an open pit mine, underground mine workings, waste rock dumps and piles of ore tailings. Mining activity has fractured the mountain exposing it to rain, surface water, groundwater and oxygen.

For much of the last century, the annual rains have sent toxic copper, cadmium and zinc from the mine into the Sacramento River. Prior to its Superfund listing on the National Priorities List, the mine discharged more than a ton a day of toxic metals into the Sacramento River. This made the mine the largest discharger of heavy metals to surface water in the nation.

In 2000, the EPA successfully settled cost recovery litigation with the former owner and operator of the site. The settlement provided $160 million to ensure that the treatment plant will be properly operated and maintained in perpetuity. Overall, the settlement assures the performance of future work at the site in the amount of between $700 million to $800 million. The settlement is one of the largest settlements in the history of the Superfund program.

For more information, visit:
https://yosemite.epa.gov/r9/sfund/overview.nsf/0/7a8166ef298804808825660b007ee658?OpenDocument