Streamside Tailings

(Silver bow Creek)

Operable Unit Information

For more than 100 years, Silver Bow Creek was used by mining and smelting companies, principally the Anaconda Company, as an industrial sewer for tailings and the acidic, metal laden water pumped from the mines.

In June of 1908, a record-breaking flood washed tailings and slag from the ore milling, concentrating and smelting operations in Butte into the Clark Fork of the Columbia River, spreading a layer of contaminated waste down the drainage as far as Milltown Dam, just upriver of Missoula.

The Superfund cleanup of Silver Bow Creek began in Butte in 1997 by removing over one million cubic yards of the Colorado Smelter tailings and rebuilding the stream and its floodplain. That work was done by Atlantic Richfield as part of the Butte Priority Soils Operable Unit.

The next 26 miles of cleanup, extending from Butte to the Warm Springs Ponds, began in 1999 under the management of Montana Department of Environmental Quality, and after removing over 6.5 million cubic yards of tailings from the bed, banks and floodplain and rebuilding the stream and floodplain with clean materials, at a cost of nearly $140M, the cleanup was largely complete by 2015. From 2016 through 2018, DEQ addressed residual contamination largely in Subareas 1 and 2. The project is currently evaluating long-term groundwater management, some additional removals, long-term operations, monitoring and management before moving to the agencies can agree on final project close out.

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