|Mike Horse Mine|
The goal of a cleaned up Blackfoot just got a whole lot closer. The U.S. Forest Service announced on July 9, 2012, that it is moving forward with “Section 35” as the chosen repository site for 1 million cubic yards of metals-contaminated mine waste piled up behind the Mike Horse dam at the river's headwaters. This long-awaited decision triggers additional studies to ensure that a fully protective repository can be built, and to figure out where within the 360-acre site the 30 acres of contaminants should sit.
When people hear the words “Blackfoot” and “River,” most conjure up visions of one of Montana’s renowned dream streams-- water tumbling from mountains cut out by the ice age, pristine habitat and shelter, wild sustenance, food-- the simple pulse of life. This is an accurate snapshot of the Blackfoot, yes-- but it doesn’t tell the full story. The full story includes the massive tailings dam looming over the river’s very origins at the Continental Divide.
In the 1940s, miners used metals-laced tailings to build the Mike Horse dam. Their idea was that a tailings dam would contain and manage their toxic mining waste. The selected dam site was across the mouth of Beartrap Creek just above its confluence with Mike Horse Creek-- 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, these metals didn’t always stay put.
In 1975, the Mike Horse tailings dam blew out, and the mine waste became a serious polluting menace to the Blackfoot. Deadly levels of lead, copper, and zinc dumped into the upper Blackfoot. The mine's corporate owner, ASARCO, rebuilt the dam shortly thereafter, and a half-hearted, fairly ineffective cleanup of the river's headwaters has slogged along since 1975.
Then, in 1993, the situation at Mike Horse took a serious wrong turn. Instead of declaring Mike Horse a state Superfund site, Montana’s Dept. of Environmental Quality (DEQ) agreed to let ASARCO experiment with a “voluntary” cleanup. The state was attracted to the voluntary cleanup idea because they felt the cleanup would be immediate. Unfortunately, it wasn't even close, and now ASARCO is sinking into bankruptcy. To further complicate matters, the cleanup is on federal, state, and private land, which mires the project in jurisdictional squabbling.
Possibly the biggest threat at the Mike Horse site is the safety of the shored-up tailings dam. The base of the dam is constructed with two million cubic yards of toxic tailings, and water is seeping out, indicating that the dam could be eroding from within. Furthermore, the dam’s spillway is not up to standards, and puts the structure at risk of overtopping in a large flood. On top of these concerns, there are threats of earthquakes in the geologically active upper Blackfoot. We need a permanent fix for the dam, and soon.
The good news is that thanks to public comments from over 8,000 citizens and hard work by conservation organizations, the Forest Service recently decided to implement a complete removal of the Mike Horse Tailings Dam, selecting the option of complete removal from among its alternatives in its Engineering Evaluation and Cost Analysis (EE/CA). The dam 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.
Other impaired stretches of the Blackfoot have been on the receiving end of millions of restoration dollars and miles of conservation legwork from landowners, environmental groups, and agency specialists. And it’s paying off in the form of cleaner water, healthier streambanks, and increased native trout populations. In fact, there’s been a marked and measurable difference in the vitality of the river these last 15 years.
What’s more, the state of Montana and the Forest Service are planning multi-million dollar cleanups of the worst of the tailings that the dam deposited in the upper river after it blew out in 1975. In the context of these giant cleanup investments, it would be foolish to leave a permanent metals-laden hazard looming at the very head of the watershed, threatening to undo all that's been accomplished thus far.
At the Clark Fork Coalition, we have pledged our support and technical input on the cleanup design and implementation. First, we will be tracking the Forest Service and the state's negotiations with ASARCO and ARCO to fund dam removal and cleanup. We will be involved in the state's efforts to restore stream channels and habitat in the upper Blackfoot and Beartrap Creek post-dam removal, and we will monitor data collection and cleanup protocol for the remainer of the Mike Horse Mine site-- the adit, upper Beartrap Creek, and water treatment systems.
The following resources provide a fuller picture of the history, challenges, and opportunities at the Mike Horse mine:
Mike Horse Dam fact sheet (produced by the Clark Fork Coalition) (PDF, 2.1MB, 2 pages)
Mike Horse Dam FAQ (produced by the Clark Fork Coalition) (PDF, 1.0MB, 2 pages)
Studies show Mike Horse dam slowly deteriorating, Eve Byron, Helena Independent Record, 5 Jan. 2005
Wounding the West: Montana, Mining, and the Environment , by David Stiller, University of Nebraska Press, 2000 (212 pages, photos, maps)
Upper Blackfoot Mining Complex, Reclamation Activities and Accomplishments (a Montana DEQ website for details about cleanup work)