The United States Department of Justice Department of Justice Seal The United States Department of Justice
Search The Site
U.S. v. Atlantic Richfield Company, et al., (D. Mont.)
Berkeley Pit at Butte, Montana. Courtesy of the USGS

U.S. v. Atlantic Richfield Company, et al., (D. Mont.)

The Anaconda Smelter Stack.  Courtesy of EPA.Following the discovery of rich copper ore deposits at Butte, Montana in the 1870's, the Clark Fork River Basin became one of the most productive mining areas in the world. From 1880-1950, one-sixth of the world’s copper came from mines operated by the Anaconda Mining Company and other concerns in Butte. Unfortunately, pollution accompanied profits. Mining and smelting these ores generated enormous quantities of mine tailings and smelter wastes which carpeted the region with arsenic, lead, and other heavy metals.

The Clark Fork Basin Superfund Sites are the legacy of mining in Butte. Encompassing over one hundred square miles that extend from Butte north along the Clark Fork River to Missoula, the sites comprise one of the largest areas of toxic contamination in the nation. In 1989, EES lawyers sued the Atlantic Richfield Company, Anaconda Mining Company’s successor, under the Superfund law.

Outcome: The resulting series of settlements has facilitated one of the most expensive (at over $1 billion) Superfund cleanups in history under the direction of the Environmental Protection Agency (EPA), the Department of the Interior, and the State of Montana.

There are four Superfund Sites in all in the Clark Fork Basin:

  1. The Silver Bow Creek/Butte Area NPL Site includes the city of Butte, where EPA is overseeing the removal of arsenic from soils and attics around town, and the massive Berkeley Pit, now more than one mile wide and one-third mile deep. When mining ceased in 1982, the dewatering of the 3,500 miles of underground mine workings surrounding the Pit by subterranean pumps was ended and the Pit began to fill with acid mine drainage. Containing over 30 billion gallons of toxic water, the Pit is the largest contaminated body of water in the nation. Rising 25 feet each year, the water level will, if unchecked, by 2018 discharge into the alluvial aquifer and a nearby stream. To prevent this, EPA’s remedy will divert and treat water to ensure the level in the Pit never exceeds 5,410 feet above sea level.

     

  2. The Anaconda Smelter Site is composed of the former Anaconda Copper Mining Company’s ore processing smelters near the town of Anaconda, 25 miles northwest of Butte, and contaminated neighboring lands. Mining, milling, and smelting activities in Anaconda produced large quantities of mine tailings and, significantly, arsenic- and lead-based airborne smelter byproducts that contaminated forests, streams, and rangeland for miles around. These resources are now in varying stages of remediation. The 585-foot Washoe Smelter, the largest of the Anaconda smelter smokestacks, stands taller than the Washington Monument and is listed on the National Register of Historic Places.

     

  3. The Berkeley Pit.  Photo courtesy Angela M. Brown, Guide to Northwest US Travel, gonw.com. The Clark Fork River Site consists of 120 miles of the Clark Fork River, from its headwaters at Warm Springs Creek, to the Milltown Reservoir near Missoula. Surface water, irrigation ditches, streambed sediments, and groundwater have been contaminated by metal-laden mine tailings waste and airborne smelter emissions. As part of the remedy, mining wastes are being removed and stream banks re-vegetated and stabilized. Water rights have been acquired to add to the river’s flow and improve wildlife habitat.

     

  4. The Milltown Reservoir Site consists of the Milltown dam, built in 1908 downstream from the other Clark Fork Basin sites, which collected contaminated sediments for 100 years before being breached as part of a Superfund remedial action in March 2008. 1.6 million cubic yards of sediments are being dredged from this now free-flowing stretch of the river, and transported by rail to waste disposal areas at the Anaconda Smelter Site.


In the News
February 7, 2008
Atlantic Richfield Company Agrees to Pay $187 Million for Montana Superfund Cleanup
The Atlantic Richfield Company (ARCO) has agreed to pay $187 million that will finance a major cleanup along 120 miles of the Clark Fork River and other areas in southwestern Montana, the Justice Department and Environmental Protection Agency announced today.
 

Last Updated: September 2014