New Reservoir Keeps Mine Waste Out of Sacramento River

REDDING, California, May 10, 2004 (ENS) - In a ceremony Thursday at the Iron Mountain Mine Superfund site in southwest Shasta County, local, state and federal 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.

The river is the major source of drinking water for more than 70,000 people in northern California.

"It took local, state and federal efforts to contain this mountain," said Wayne Nastri, administrator of the U.S. Environmental Protection Agency'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."

The defunct 4,400 acre open pit and underground copper Iron Mountain Mine operated between 1860 and 1962. The mine was placed on the Superfund list in 1983, and at that time acid mine drainage containing more than one ton of toxic metals was released into the environment every day. This made the mine the largest discharger of heavy metals to surface water in the nation.

The Iron Mountain Mine discharge was a cause of the decline of the Sacramento River salmon and steelhead fishery. Today this fishery is on its way to recovery.

In 2000, the EPA 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.

In 1994, the completion of a wastewater treatment plant prevented some of the 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 about 1.9 million pounds of copper and 6.6 million pounds of zinc out of the environment.

The Iron Mountain 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.