A Legacy of Mining Pollution in the Clark Fork
Long before we had environmental laws, mining wastes were sluiced directly into our rivers and streams. The contaminated sediment, known as tailings, is laced with heavy metals that can pollute drinking water sources, threaten crops and riparian plants, and poison fish and aquatic life. The Coalition is dedicated to making sure spots with the worst mining waste are cleaned up from our watershed.
Why the mess?
Mining and smelting operations in Butte and Anaconda at the headwaters of the Clark Fork River delivered copper to our nation for a century. More mines — industrial-size and tiny alike — dot almost every corner of our watershed. Mining provided jobs, drove economic growth, and helped put Montana on the map. The river, however, paid the price.
A massive flood in 1908 washed millions of tons of toxic sediment downstream from Butte, depositing metal-laced tailings in the floodplain for more than 120 river miles. The toxic mud stacked up behind the former Milltown Dam at the confluence of the Clark Fork and Blackfoot rivers near Missoula, where it remained for 100 years.
In 1981, Missoula County health officials discovered arsenic in drinking water wells near the Milltown Reservoir, sparking a decades-long, collaborative effort to list the Clark Fork River as a Superfund site, and clean up a century’s worth of mine waste from the river system.
Cleaning up our headwaters
Today, the river looks much different than it did 30 years ago. At the headwaters, Superfund cleanup and restoration work on Silver Bow Creek has brought this critical headwaters stream back from the brink, and today the creek boasts a native cutthroat trout fishery. Downstream, the removal of Milltown Dam and the metal-rich sediment stacked behind it has eliminated a hundred-year old pollution problem, and the Clark Fork and Blackfoot rivers are once again reunited in a natural, free-flowing confluence.
Despite successful cleanups in Silver Bow Creek and Milltown, the river between them remains contaminated, and functions at only one-fifth of its fishery potential. Patches of copper-rich, blue-colored dead zones, still riddle the floodplain of the Clark Fork from Warm Springs to Garrison.
Now, finally, this piece of the Superfund puzzle is falling into place. Cleanup of the main stem of the Clark Fork River officially began in 2012 at the Trestle area in Deer Lodge. The main stem cleanup will take place mostly on private land, and is anticipated to continue for about 15 years. In 2013, Montana’s Department of Environmental Quality completed Phase 1 of the Upper Clark Fork Cleanup, removing over 330,000 cubic yards of mine waste from 1.6 miles of Clark Fork floodplain just downstream of Warm Springs Ponds. In 2014-2016, they cleaned up the floodplain on the CFC’s Dry Cottonwood Creek Ranch, and in 2020 completed work at Grant-Kohrs Ranch National Historic Site. Work now moves to Phases 3-4, south of Galen Road. (Learn more about Superfund cleanup from DEQ’s Clark Fork River Cleanup Fast Facts.)
For an overview of the history of the Upper Clark Fork and evolution of the Superfund cleanup, check out the video, Superfund: Tailing History.
Removing a threat to the beautiful Blackfoot
When people hear the words “Blackfoot,” most conjure up visions of one of Montana’s renowned fishing streams. Yet this vision doesn’t tell the full story, which includes a massive tailings dam looming over the river’s origins at the Continental Divide.
In the 1940s, miners used metals-laced tailings to build the Mike Horse dam to contain toxic waste from the mine. The dam was constructed across the mouth of Beartrap Creek just above its confluence with Mike Horse Creek — the spot where the Blackfoot River officially begins. The shallow reservoir behind the dam became the resting place for metals-laced tailings from the Mike Horse Mine as well as other gold, copper and zinc mines scattered around the river’s headwaters.
Unfortunately, the dam didn’t hold. In 1975, the Mike Horse tailings dam blew out, and deadly levels of lead, copper and zinc dumped into the upper Blackfoot. The mine’s corporate owner, ASARCO, rebuilt the dam shortly thereafter, but the safety of the shored-up dam has always been in question. Its base is constructed with 2 million cubic yards of toxic tailings, and polluted water is seeping out — indicating that the dam could be eroding from within. Furthermore, the dam’s spillway is not up to standards, and the structure is at risk of overtopping in a large flood.
Fortunately, a cleanup solution is underway at the Mike Horse Dam. Thanks to public comments from more than 8,000 citizens and hard work by conservation organizations, in 2007 the U.S. Forest Service decided to implement a complete removal of the dam. The structure will be dismantled, mine tailings will be moved to high and dry land and stored in a safe repository, and the headwaters of the Blackfoot will be given an opportunity to heal after a quarter-century of enduring intense pollution. We continue to track this project and look forward to celebrating a successful cleanup in a few more years. (Update 2021: Read about completed cleanup at Mike Horse Mine here.)
Beal Mountain: A mining mess we could do without
Montana has over 8,400 abandoned mines, with 2,400 in the Clark Fork basin alone. Although abandoned mines are no longer in operation, they continue to pollute streams and threaten public safety. It’s a legacy we can do without.
In the Clark Fork basin, the most recent example of a leftover mining mess is at Beal Mountain, now out of operation. Beal was an open-pit, cyanide heap-leach mine situated on mostly USFS-owned in German Gulch near Anaconda in the headwaters of the Upper Clark Fork. In 1998, the mine’s owners, Pegasus Gold, declared bankruptcy and abandoned Beal Mountain, leaving the USFS to deal with massive pollution problems.
Pegasus left behind a 70-acre, cyanide-contaminated leach pond with a leaky liner and waste rock that delivers selenium-laced runoff into streams, threatening cutthroat trout and other fish in German Gulch. The $6.2 million reclamation bond posted by the company doesn’t come close to covering the full cost to clean up the mine, which was recently estimated at nearly $40 million. As of 2012, the USFS (i.e., taxpayers) had spent $8 million to $9 million above the bond to prevent this site from becoming a major environmental disaster.
The USFS spends several hundred thousand dollars a year just to treat water, and whenever it can find extra funds they chip away at patchwork of reclamation projects and additional studies to figure out the complex hydrology and chemistry of the site. Although the funds to do a complete cleanup may never materialize, the USFS is making progress. Cyanide is now below detection in the stream, and selenium levels are much lower. Selenium levels in fish are still problematic because it causes deformities in developing trout eggs. Unfortunately, selenium contamination from Beal Mountain Mine is going to persist in the headwaters for years to come.
Permanent cleanup here will take technical ingenuity, perseverance, political will and funding. And the next time industry wants Montana to open its doors to cyanide heap-leach mining, we will turn to a vivid example at Beal Mountain as argument for keeping this dangerous technology away from our rivers, lakes and streams. (Learn more about current conditions and ongoing cleanup concerns at Beal Mountain here.)
For more information about Superfund cleanup or cleanup of abandoned mines in the Clark Fork basin, please contact John DeArment at 542-0539 ext. 211.