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EPA finds risk to Clark Fork life


A report issued recently by the U.S. Environmental Protection Agency (EPA) has found that mining and smelting wastes along the upper Clark Fork River continue to pose an adverse and unacceptable risk to animals, creating the potential for future fish kills along the river.

Those findings, released in the EPA’s “Clark Fork River Ecological Risk Assessment,” are part of the ongoing Superfund process begun in 1995 to address more than 100 years of mining and smelting activities along the Upper Clark Fork River in Anaconda and Butte. That report, now available to the public, will be discussed in greater detail at two public meetings, the first in Deer Lodge on Jan. 19 and the second in Missoula on Jan. 20.

During the mid- to late-1980s, the Clark Fork River experienced periodic incidents of fish kills, most notably in July 1989, when several thousand trout were found floating dead in the river. According to Scott Brown of the EPA’s Region 8 office, the potential for another fish kill of that severity remains.

“The same conditions that were present in 1989 just haven’t repeated themselves,” says Brown. “But we have every reason to believe that if we had drying conditions in the summer followed by thunderstorms, where water would be running off these exposed [mine] tailings areas, that fish kills could occur again.”

The EPA conducted a separate human health risk assessment that was published in January 1998. That report found that hazardous substances still exist along the floodplain and within the waters of the Clark Fork River, particularly in the upper reaches between Warm Springs and Garrison.

However, the EPA also found that the opportunities for exposure by humans are less frequent, with the highest risks to people who recreate along the river frequently (i.e., 40 days or more each year) such as teenagers who float or swim in the upper Clark Fork, or people who work regularly along the river. None of the human health risks exceeded what the EPA considers an acceptable level, says Brown, not because the hazardous substances aren’t there, but simply because the opportunity for exposure is not as pronounced.

This latest ecological risk assessment report is a prelude to the EPA’s feasibility study, scheduled to begin in February, which will consider the various clean-up options that may begin as early as the January 2002.

Among the three options that will likely be considered will be to leave sections of the river alone so that they can heal themselves, remove and replace the highly acidic exposed tailings areas (known as “slickens”) or treat some the exposed tailings areas by adding lime and other organic material to encourage plant growth, thus reducing the flow of metals into the rivers, neutralizing the soil pH and reducing sediment in the river.


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