Water Resources Research Act Program

Principal Investigators: Mariah Mayfield

Abstract: Since the beginning of human civilization, societies have exploited the environment to better serve their goals. Much of the exploitation of natural resources has occurred in the form of mining. In the Clark Fork River basin, located in southwestern Montana, mining has dramatically changed the environment permanently, with the deposition of hazardous contaminated sediments, large scale fish kills, and reduced ground water quality. Mining began in the Butte, Montana area in 1864. Mining activity increased dramatically in the area, and, by 1955, large open-pit mines replaced most of the small scale mining operations (3). As was typical with mining operations in the late 1880's, the tailings (contaminated sediment leftover from the mining process) were allowed to flow directly into local watersheds. These tailings contained high levels of metals such as copper, cadmium, mercury, lead, arsenic, and zinc. Settling ponds were constructed beginning in 1911 and completed in 1959, near the town of Warm Springs, as a way to collect contaminated tailings and settle them out of Silver Bow Creek, before entering the Clark Fork River. Although these ponds greatly improved water quality and contaminated sediment deposition downstream of the ponds, the damage had already been done. Prior to the completion of the settling ponds, it is estimated that 100 billion kilograms of contaminated mining waste had already been deposited in the Clark Fork River (3). The deposition of mining waste came at a great cost to the environmental quality of the Clark Fork River. In 1950, the State of Montana conducted electrofishing surveys on the river near the town of Garrison and concluded that there were no fish in the river (6). Improvements to the Butte waste water treatment facility occurred in the early 1970s, which began to bring back fish populations, although fish kills were still observed even into the 1990s (6). These fish kills have been associated with high flow events, such as summer thunderstorms, where either the settling ponds overflow or stream banks containing high levels of contaminated soils wash into the river. Currently, the trout species present in the upper Clark Fork include brown trout, westslope cutthroat trout, rainbow trout, cutthroat/rainbow trout hybrids, and bull trout. Fish and other aquatic life have not been the only organisms to suffer. The increased amount of hazardous heavy metals in the soil has created an exposure pathway directly to groundwater supplies in the area (2). Many local areas are no longer on well water due to the negative health effects of heavy metals present in the ground water. In 1983, the U.S. Environmental Protection Agency (EPA) placed the Clark Fork River/Silver Bow Creek area on the Superfund list, a list of hazardous waste sites that pose a threat to human and environmental health (6). The EPA found that in the upper 60 km of river, the Clark Fork sediments contain 1000 times greater concentration of copper than other tributaries in the area (3). Since 1990, the State of Montana, through the Natural Resource Damages Program (a division of the Montana Department of Justice), has been receiving monetary settlements with the Atlantic Richland Company, with the money being set aside for remediation of the area.