Trace Elements in Streams Near the Stibnite Mining Area

Science Center Objects

Mining of stibnite (antimony sulfide), tungsten, gold, silver, and mercury near the town of Stibnite in central Idaho has left a legacy of trace element contamination in the East Fork of the South Fork of the Salmon River (EFSFSR) and its tributaries. Concentrations of arsenic, antimony, and mercury frequently exceed human health criteria and may impact threatened or endangered salmonid species, including Chinook salmon, steelhead, and bull trout in the EFSFSR. The purpose of this study is to quantify contributions of select trace elements and suspended sediment from different stream reaches, assess potential toxicity to human and aquatic life, and explore the use of surrogate parameters such as specific conductance to improve estimates of concentrations and loads of select constituents.


To quantify trace elements entering discrete stream reaches, we will:

  • Establish a network of five streamgaging stations to collect stage and streamflow data
  • Equip each streamgaging site with continuous water-quality monitoring sensors to collect pH, water temperature, and specific conductance data
  • Collect and analyze water-quality samples for major ions, suspended sediment, and trace element concentrations

To produce spatially detailed trace element profiles, we will:

  • Conduct a synoptic water-quality sampling and tracer dilution study on a 5-km reach starting on Meadow Creek upstream of the primary mine tailings area and downstream along the East Fork of the South Fork of the Salmon River
  • Analyze the synoptic data with a solute-transport model to simulate ambient water-quality conditions, evaluate loading to discrete stream reaches, and simulate the effects of hypothetical remediation scenarios on water quality