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A Horse Named Mike

Couple of good articles in the Great Falls Tribune this morning about the Mike Horse mine project near Lincoln. One article gives a pretty good overview of the of the history of the remediation project and the other outlines some recent changes in funding. Both articles are taken from the masters thesis project of Elizabeth Harrison of the UM School of Journalism.


Acid mine drainage in Beartrap Creek - Photo by Stuart Jennings

The Mike Horse Mine is part of the Upper Blackfoot Mining Complex (UBMC) also know as the Heddleston district. The area was severely polluted by mine waste between the 1880s and the 1950s. Originally consisting of small lead, silver and zinc deposits, shortly after the turn of the century mining activities were expanded. In 1941 the Mike Horse Mining and Milling Company built a dam across Beartrap Creek. The dam was built of toxic mine tailings and was used to contain 350,000 cubic yards of tailings slurry from the mill operation. Tailings, waste rock dumps and acid mine drainage from old adits have contaminated surface water, sediments, soils and groundwater throughout the area. ASARCO bought the site in 1945 and operated it for 10 years. In the 1960s Anaconda Copper leased 30,000 acres believing that it had found the mother lode of copper deposits in the area. The mineral deposits never proved viable and due to tightened mining laws and lower ore prices, the Anaconda Company was never able to develop the deposits.

Heavy rains in 1975 breached the Mike Horse Dam pouring contaminated sediments down Beartrap Creek and the nearby Blackfoot River destroying 10 miles of fish and insect life and badly impacting the entire Blackfoot. The Anaconda Company repaired the dam but it has continued to leak toxins. In 1977, the Anaconda Company was acquired by Atlantic Richfield (ARCO) and the state held both ARCO and ASARCO responsible for the cleanup. As part of a bankruptcy process and litigation against the two companies the state was awarded $37 million in 2008. ARCO and ASARCO each put up $8 million along with about $1.5 million to the Forest Service to administer the project. About another $20 million is due from ASARCO as they try to come out of bankruptcy, but since the company has been hit hard by the current downturn, it is not likely that Montana will ever see that money. Earlier this month, a federal judge approved putting $138 million into a trust fund for settlement of all environmental claims against ASARCO in Montana. The Mike Horse project should see about $10 million of that money as well.

ASARCO has built a state-of-the-art water treatment plant at the site to remove metals contamination from the current seeps. The plan is still to remove the dam and sediments and to restore the watershed to pre-mining conditions. For now, Mike Horse still leaks poison downstream and sits like a smoking bomb in the headwaters of the river that inspired Norman Maclean waiting for a hard rain to fall.


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