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.

This U.S. Geological Survey (USGS) data release is an assessment of aquatic habitat within the tributaries of the lower Middle Fork Salmon River. These datasets are primarily focused on physical stream habitat (2020-21 stream temperature data) and the presence or absence (2021 eDNA data) of fish that inhabit the basin. Many environmental stressors contribute to the declining range and density of Bull trout (S. confluentus) populations, one of which is the toxic trace metals contributions from legacy mine waste and adits. These data were collected in stream habitats with variable physical and thermal conditions. Characterizing and comparing reference streams of similar physical attributes will assist to differentiate the regional impacts of toxic trace metals exposure.

This U.S. Geological Survey (USGS) data release is an assessment of aquatic habitat within the tributaries of the lower Middle Fork Salmon River. These datasets are primarily focused on physical stream habitat (2020-21 stream temperature data) and the presence or absence (2021 eDNA data) of fish that inhabit the basin. Many environmental stressors contribute to the declining range and density of Bull trout (S. confluentus) populations, one of which is the toxic trace metals contributions from legacy mine waste and adits. These data were collected in stream habitats with variable physical and thermal conditions. Characterizing and comparing reference streams of similar physical attributes will assist to differentiate the regional impacts of toxic trace metals exposure.

Samples were collected at or near baseflow conditions. Water pH and specific conductance were measured in the field, with specific conductance also measured in the laboratory and calculated based on the ionic strength of samples based on laboratory analyses. Water samples were collected for laboratory analyses using a peristaltic pump with silicon tubing. Samples were filtered through a reusable plexiglass filter holder with nylon screws using 0.45µm polyethersulfone membranes that were rinsed with approximately 20mL of sample water prior to collection. Splits were also collected unfiltered to determine trace metal concentrations associated with suspended sediments. The filtration apparatus was rinsed with deionized water between samples. Separate filtration apparatuses were used for mining-impacted sites and background sites to minimize sample cross-contamination. Field equipment blanks were collected at the end of a field day using the full sampling apparatus used for mining-impacted sites to determine carryover of constituents between samples. Samples were chilled to approximately 4°C and transported by overnight shipping to USGS analytical laboratories. Mercury and methylmercury were analyzed in the USGS Mercury Laboratory in Middleton, WI. Note that mercury concentrations in the field blanks exceeded concentrations in sites considered to be background. Sources of sample contamination may be the filter, which was not pre-cleaned, and the filtration apparatus that was previously used in stream reaches directly impacted by mercury mining. The detection limit for mercury was less than 0.04 ng/L. Field blanks had 1.96 and 2.45 ng/L Hg. Streambed sediment samples were collected as grab samples and stored in pre-cleaned glass jars, frozen on dry ice to minimize microbial activity associated with the formation and degradation of methylmercury. Sediment samples and shipped to USGS laboratories in Denver, CO for total elemental analysis, including mercury, and to Middleton, WI for methylmercury analysis. Sediment was dominantly fine to coarse sand trapped between cobbles in a high-energy stream environment. Samples were sieved to less than 2mm and hand-crushed to homogenize prior to trace metal analysis in Denver.

Samples were collected at or near baseflow conditions. Water pH and specific conductance were measured in the field, with specific conductance also measured in the laboratory and calculated based on the ionic strength of samples based on laboratory analyses. Water samples were collected for laboratory analyses using a peristaltic pump with silicon tubing. Samples were filtered through a reusable plexiglass filter holder with nylon screws using 0.45µm polyethersulfone membranes that were rinsed with approximately 20mL of sample water prior to collection. Splits were also collected unfiltered to determine trace metal concentrations associated with suspended sediments. The filtration apparatus was rinsed with deionized water between samples. Separate filtration apparatuses were used for mining-impacted sites and background sites to minimize sample cross-contamination. Field equipment blanks were collected at the end of a field day using the full sampling apparatus used for mining-impacted sites to determine carryover of constituents between samples. Samples were chilled to approximately 4°C and transported by overnight shipping to USGS analytical laboratories. Mercury and methylmercury were analyzed in the USGS Mercury Laboratory in Middleton, WI. Note that mercury concentrations in the field blanks exceeded concentrations in sites considered to be background. Sources of sample contamination may be the filter, which was not pre-cleaned, and the filtration apparatus that was previously used in stream reaches directly impacted by mercury mining. The detection limit for mercury was less than 0.04 ng/L. Field blanks had 1.96 and 2.45 ng/L Hg. Streambed sediment samples were collected as grab samples and stored in pre-cleaned glass jars, frozen on dry ice to minimize microbial activity associated with the formation and degradation of methylmercury. Sediment samples and shipped to USGS laboratories in Denver, CO for total elemental analysis, including mercury, and to Middleton, WI for methylmercury analysis. Sediment was dominantly fine to coarse sand trapped between cobbles in a high-energy stream environment. Samples were sieved to less than 2mm and hand-crushed to homogenize prior to trace metal analysis in Denver.

The California State Water Resources Control Board (State Water Board) initiated the Oil and Gas Regional Monitoring Program (RMP) to assess effects of oil and gas development on groundwater designated for any beneficial use. The U.S. Geological Survey (USGS) is the technical lead in conducting the RMP through the California Oil, Gas, and Groundwater (COGG) Program, working in cooperation with the State Water Board, and in partnership with other State and local agencies. The USGS collected and analyzed groundwater, surface water, and associated quality control (QC) samples in the Elk Hills study area during June 2017–April 2018. The Elk Hills study area includes the Elk Hills and North Coles Levee Oil Fields and a five-kilometer buffer zone surrounding the administrative boundaries of the two oil fields in Kern County, California. Water samples were collected from twenty-six monitoring wells, four irrigation wells, two public supply wells, and one managed recharge pond. Samples were collected using established groundwater data-collection protocols and procedures. Samples were analyzed for water-quality indicators, major and minor ions, nutrients, trace elements, volatile organic compounds (VOCs), naturally occurring radioactive material, geochemical and age-dating tracers, dissolved organic carbon (DOC) characteristics, dissolved standard and hydrocarbon gases (methane through hexane), and dissolved noble and atmospheric gases. Over 200 constituents and water-quality indicators were measured. Quality-control samples collected as part of this study included replicates, field blanks, equipment blanks, source-solution blanks, and matrix spikes.

The California State Water Resources Control Board (State Water Board) initiated the Oil and Gas Regional Monitoring Program (RMP) to assess effects of oil and gas development on groundwater designated for any beneficial use. The U.S. Geological Survey (USGS) is the technical lead in conducting the RMP through the California Oil, Gas, and Groundwater (COGG) Program, working in cooperation with the State Water Board, and in partnership with other State and local agencies. The USGS collected and analyzed groundwater, surface water, and associated quality control (QC) samples in the Elk Hills study area during June 2017–April 2018. The Elk Hills study area includes the Elk Hills and North Coles Levee Oil Fields and a five-kilometer buffer zone surrounding the administrative boundaries of the two oil fields in Kern County, California. Water samples were collected from twenty-six monitoring wells, four irrigation wells, two public supply wells, and one managed recharge pond. Samples were collected using established groundwater data-collection protocols and procedures. Samples were analyzed for water-quality indicators, major and minor ions, nutrients, trace elements, volatile organic compounds (VOCs), naturally occurring radioactive material, geochemical and age-dating tracers, dissolved organic carbon (DOC) characteristics, dissolved standard and hydrocarbon gases (methane through hexane), and dissolved noble and atmospheric gases. Over 200 constituents and water-quality indicators were measured. Quality-control samples collected as part of this study included replicates, field blanks, equipment blanks, source-solution blanks, and matrix spikes.

Charcoal counts and soil, water, and reservoir sediment-core geochemistry were characterized eight months after the November 2021 Muckamuck Fire in the North Fork Salmon Creek basin and Conconully Reservoir, Washington, the receiving water body. Parameters include sand-sized charcoal, Cesium-137, excess Lead-210, aqueous and solid-phase elemental chemistry, and polycyclic aromatic hydrocarbon concentrations (PAHs). Grain size and carbon were measured in select intervals in the longest sediment core.