Long-Term Surface-Water Monitoring in the Upper Clark Fork River Basin
Suspended sediment collection at Turah bridge near Bonner, MT
Clark Fork River near Galen, MT
Documenting channel conditions during water-quality sampling
at Silver Bow Creek below Blacktail Creek at Butte, MT
The U.S. Geological Survey (USGS) has collected water-quality samples from selected stream sites upstream from Missoula since 1985.
The USGS began collecting surface water-quality data in the upper Clark Fork Basin in 1985 to establish baseline metal concentrations and loads and was later expanded in 1992 in cooperation with the U.S. Environmental Protection Agency (USEPA) to provide consistent long-term data at a network of sites. The sampling was initiated in response to elevated trace-element concentrations and the designation of areas in the upper Clark Fork basin by the USEPA as National Priorities List Superfund sites. This water-quality information aids the public and local, State, Federal, and Tribal governments in assessing risks to aquatic resources, facilitating resource-management decisions, and evaluating the effectiveness of remediation. In addition to water-quality data, the long-term monitoring program also obtains daily records of streamflow, suspended sediment, and turbidity at selected sites, as well as trace-element data for biota and bed sediment.
The Clark Fork originates near Warm Springs in western Montana at the confluence of Silver Bow and Warm Springs Creeks. Along the 148-mile reach of stream from Silver Bow Creek in Butte to the Clark Fork near Missoula, six major tributaries enter: Blacktail Creek, Warm Springs Creek, Little Blackfoot River, Flint Creek, Rock Creek, and Blackfoot River. Large-scale mining and smelting were prevalent land uses in the upper basin for more than 100 years but are now either discontinued or substantially smaller in scale.
Deposits of copper, gold, silver, and lead ores were extensively mined, milled, and smelted in the drainages of Silver Bow and Warm Springs Creeks from about the 1860s to the 1980s. Moderate- and small-scale mining also occurred in the basins of most of the major tributaries to the Clark Fork. Tailings derived from past mineral processing commonly contain large quantities of trace elements such as arsenic, cadmium, copper, lead, and zinc. Tailings have been eroded; mixed with stream sediment; transported downstream; and deposited in stream channels, on flood plains, in the Warm Springs Ponds, and where the former Milltown Reservoir was located (Andrews, 1987). The widely dispersed tailings continue to be remobilized, transported, and deposited along the stream channel and flood plain, especially during high flows. The occurrence of elevated trace-element concentrations in water and bed sediment can pose a potential risk to aquatic biota and human health (U.S. Environmental Protection Agency, 2004; Montana Department of Environmental Quality, 2012).
The U.S. Geological Survey (USGS) has collected water-quality samples from selected stream sites upstream from Missoula since 1985.
The USGS began collecting surface water-quality data in the upper Clark Fork Basin in 1985 to establish baseline metal concentrations and loads and was later expanded in 1992 in cooperation with the U.S. Environmental Protection Agency (USEPA) to provide consistent long-term data at a network of sites. The sampling was initiated in response to elevated trace-element concentrations and the designation of areas in the upper Clark Fork basin by the USEPA as National Priorities List Superfund sites. This water-quality information aids the public and local, State, Federal, and Tribal governments in assessing risks to aquatic resources, facilitating resource-management decisions, and evaluating the effectiveness of remediation. In addition to water-quality data, the long-term monitoring program also obtains daily records of streamflow, suspended sediment, and turbidity at selected sites, as well as trace-element data for biota and bed sediment.
The Clark Fork originates near Warm Springs in western Montana at the confluence of Silver Bow and Warm Springs Creeks. Along the 148-mile reach of stream from Silver Bow Creek in Butte to the Clark Fork near Missoula, six major tributaries enter: Blacktail Creek, Warm Springs Creek, Little Blackfoot River, Flint Creek, Rock Creek, and Blackfoot River. Large-scale mining and smelting were prevalent land uses in the upper basin for more than 100 years but are now either discontinued or substantially smaller in scale.
Deposits of copper, gold, silver, and lead ores were extensively mined, milled, and smelted in the drainages of Silver Bow and Warm Springs Creeks from about the 1860s to the 1980s. Moderate- and small-scale mining also occurred in the basins of most of the major tributaries to the Clark Fork. Tailings derived from past mineral processing commonly contain large quantities of trace elements such as arsenic, cadmium, copper, lead, and zinc. Tailings have been eroded; mixed with stream sediment; transported downstream; and deposited in stream channels, on flood plains, in the Warm Springs Ponds, and where the former Milltown Reservoir was located (Andrews, 1987). The widely dispersed tailings continue to be remobilized, transported, and deposited along the stream channel and flood plain, especially during high flows. The occurrence of elevated trace-element concentrations in water and bed sediment can pose a potential risk to aquatic biota and human health (U.S. Environmental Protection Agency, 2004; Montana Department of Environmental Quality, 2012).