Clark Fork Water-Quality Monitoring

Science Center Objects

The U.S. Geological Survey (USGS) has collected water-quality samples from selected stream sites upstream from Missoula since 1985.

Sampling was initiated in response to elevated trace-element concentrations and the designation of areas in the upper Clark Fork basin by the U.S. Environmental Protection Agency (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 periodically-collected 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. In 1993, a long-term monitoring program was implemented in cooperation with the USEPA at an expanded network of sites in the upper Clark Fork basin. In 2006, supplemental sampling was initiated in cooperation with the USEPA at sites in the lower Clark Fork basin from near Milltown Reservoir to the Flathead River to obtain additional water-quality information related to the removal of Milltown Dam in 2008.