Water chemistry data from the Big Creek and Monumental Creek tributaries of the Lower Middle Fork Salmon River, Idaho, 2021

This USGS data release evaluates the impact of historical mining sites on water quality using samples collected in late July 2021 from Big Creek tributaries Coin Creek, Smith Creek, and Monumental Creek in Valley County, Idaho. These data were collected to support a fisheries mining impact assessment in the Middle Fork Salmon River. Specific conductance, pH, and stream temperature were measured in the field. Analyses include major cations and anions, alkalinity, trace metals, total mercury, and methylmercury.