The upper Clark Fork (UCF) river has its headwaters in Butte, Montana, which is home to the largest Superfund site in the United States. A century of intensive hard rock mining activities in numerous tributaries throughout the watershed has resulted in extant pollution of arsenic, lead, copper, zinc, and cadmium in surface waters and sediments in the UCF despite ongoing remediation efforts. Sources of metals to the UCF include aquifers in former mining areas that emerge as springs and seeps that flow into UCF tributaries. Microbes affect metal concentration and speciation in fluids and sediments of these springs, tributaries, and the UCF by a variety of mechanisms, including detoxification and metabolic processes. These processes can lead to major changes in the composition of both sediments and overlying fluids. The overarching goal of this research is to determine the role of microbes in controlling the transport, speciation, and overall flux of metals in mine impacted waters in and around Butte to inform restoration efforts in the broader UCF watershed. Methods include geochemical and microbial community characterization, microcosm experiments, laboratory-based microbiology experiments, and geochemical analysis. Preliminary results have shown that iron and sulfate metabolism, which are associated with numerous covariant metal transformations, are particularly prevalent in these systems. Undergraduate participation is appropriate and encouraged in all aspects of this project. The interdisciplinary project allows students to contribute to the project by focusing on either microbiology, geochemistry, or analytical chemistry, depending on their interests and career goals. Students will be guided as they design a hypothesis, experiments, and methodology to evaluate the magnitude and environmental consequences of a process of their choosing.