Page 799 - The Toxicology of Fishes

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Mining Impacts on Fish in the Clark Fork River,

Montana: A Field Ecotoxicology Case Study

Samuel N. Luoma, Johnnie N. Moore, Aïda Farag,
Tracy H. Hillman, Daniel J. Cain, and Michelle Hornberger

CONTENTS
Introduction............................................................................................................................................779
History of the Clark Fork Mining and Smelting Complex...................................................................780
The Mining/Smelting Sites....................................................................................................................781
The Clark Fork River System................................................................................................................781
Distribution of Contamination (Indicators of Exposure)......................................................................782
Dispersal of Contamination from Mining and Smelting.............................................................782
Effect of the Ore Body.................................................................................................................782
Silverbow Creek...........................................................................................................................783
Warm Springs Ponds....................................................................................................................784
The Environment within 2 km of the Warm Springs Ponds.......................................................784
Upper Clark Fork River ...............................................................................................................785
Floodplain and Bank Contamination .................................................................................785
Water Contamination..........................................................................................................786
Sediment Contamination ....................................................................................................788
Reservoirs............................................................................................................................790
Invertebrate Exposures to Contaminants............................................................................790
Adverse Effects on Invertebrates........................................................................................792
Effects on Fish....................................................................................................................794
Conclusions............................................................................................................................................800
References..............................................................................................................................................801

Introduction
Large-scale mining and smelting operations are required to satisfy the many demands of modern societies
for metals, but few individual human activities visually disturb the Earth’s surface more dramatically or
have more potential to create hazardous waste problems than a mine. Mining activities cover about
240,000 km of the Earth’s surface (Salomons and Forstner, 1984), an area about the size of Oregon in
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the United States. Understanding such disturbances is essential to remediation of historic legacies and
to sustaining responsible mining in the decades and century ahead. In this chapter, we consider the
factors involved in determining contamination risks to fish in a mine-impacted river, the Clark Fork
River in Montana. Traditional approaches to evaluating ecological risks from mining and metal contam-
ination rely largely on toxicology: comparing controlled studies of metal toxicity to fish with observations
of ambient concentrations. In a natural water body such as the Clark Fork, however, risks develop from
complex interactions among hydrologic, geochemical, and biological processes that affect both exposure
and ecological effects. Both field observations and laboratory experiments are essential to unraveling
the complexities of these risks.

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