The trace element selenium is an essential element with a narrow window between concentrations needed to support life and those that cause toxicity to egg laying organisms. Selenium bioaccumulation in aquatic organisms is primarily the result of trophic transfer through food webs and is poorly predicted by dissolved concentrations in freshwater bodies. To better understand the hydrologic and biological dynamics that control selenium accumulation into fishes of the Lower Gunnison River Basin (Colorado), ecosystem scale selenium accumulation models were developed from data collected between June 2015 and October 2016.

The U.S. Geological Survey (USGS), in cooperation with the Bureau of Reclamation, completed a review of dissolved selenium data collected from the Selenium Management Program network during each water year (WY) in the lower Gunnison River Basin, in western Colorado. The data tables include dissolved-selenium concentrations, selected streamflow data, and computed loads as well as dissolved-selenium regression model calibration and output tables. Concentration and streamflow data are compiled from the USGS National Water Information System database. Tables include monitoring location identification information, data collection time frames, concentration data, as well as calculations of mean, median, select percentiles, and percentage reduction in loads. Tables are organized by each year, with a zipped folder for WY 2018 (October 1, 2017 through September 30, 2018), WY 2019 (October 1, 2018 through September 30, 2019), WY 2020 (October 1, 2019 through September 30, 2020), WY 2021 (October 1, 2020 through September 30, 2021), and WY 2022 (October 1, 2021 through September 30, 2022). Within each zipped folder is a metadata .xml file describing each comma-separated value (.csv) data file contained therein. The methods used to complete this review are available in Henneberg (2018) and Mayo and Leib (2012). Version 3.0 contains additional zipped folders for WY 2021 and 2022, which were not included in the original data release. While previous versions are available from the author, all records in previous versions can be found in version 3.0. First posted - April 23, 2021 (available from author) Revised - June, 2022 (version 2.0) Revised - July, 2023 (version 3.0)

The U.S. Geological Survey (USGS), in cooperation with the Bureau of Reclamation, completed a review of dissolved selenium data collected from the Selenium Management Program network during each water year (WY) in the lower Gunnison River Basin, in western Colorado. The data tables include dissolved-selenium concentrations, selected streamflow data, and computed loads as well as dissolved-selenium regression model calibration and output tables. Concentration and streamflow data are compiled from the USGS National Water Information System database. Tables include monitoring location identification information, data collection time frames, concentration data, as well as calculations of mean, median, select percentiles, and percentage reduction in loads. Tables are organized by each year, with a zipped folder for WY 2018 (October 1, 2017 through September 30, 2018), WY 2019 (October 1, 2018 through September 30, 2019), WY 2020 (October 1, 2019 through September 30, 2020), WY 2021 (October 1, 2020 through September 30, 2021), and WY 2022 (October 1, 2021 through September 30, 2022). Within each zipped folder is a metadata .xml file describing each comma-separated value (.csv) data file contained therein. The methods used to complete this review are available in Henneberg (2018) and Mayo and Leib (2012). Version 3.0 contains additional zipped folders for WY 2021 and 2022, which were not included in the original data release. While previous versions are available from the author, all records in previous versions can be found in version 3.0. First posted - April 23, 2021 (available from author) Revised - June, 2022 (version 2.0) Revised - July, 2023 (version 3.0)

This Data Release presents multi-agency data for selenium concentrations in ecosystem media that includes water column, suspended particulate material, zooplankton, invertebrates, and fish. Because the data are compiled from multiple sources, the significant figures used to report contaminant concentrations and other metrics may not be internally consistent. These data will serve as the basis for ecosystem-scale modeling of Lake Koocanusa, a bi-national reservoir in Montana and British Columbia. Spreadsheets are ordered in a food-web format to facilitate modeling that emphasizes spatially and temporally paired data. Selenium concentrations are species-specific for fish and taxa-specific for invertebrates to address required specificity for biodynamic dietary modeling. Phytoplankton, zooplankton, and invertebrate densities or biomass are compiled, in addition to fish catches, to help elucidate productivity and identify which groups, taxa, or species are abundant on a seasonal basis. For water quality context, the historical record of selenium concentrations is given, with emphasis on the primary selenium loading site near where the Elk River enters Lake Koocanusa. Spreadsheets with the term "annex" in their file name address a competing toxin, mercury, for fish. Recent high frequency monitoring of selenium concentrations at the international border and at a gaging station below Libby Dam provide a perspective on future selenium data availability. Methodologies are described as federal, provincial, and state agencies transition to a consistent set of protocols to ensure consistency in monitoring for locations on both sides of the border.

This Data Release presents multi-agency data for selenium concentrations in ecosystem media that includes water column, suspended particulate material, zooplankton, invertebrates, and fish. Because the data are compiled from multiple sources, the significant figures used to report contaminant concentrations and other metrics may not be internally consistent. These data will serve as the basis for ecosystem-scale modeling of Lake Koocanusa, a bi-national reservoir in Montana and British Columbia. Spreadsheets are ordered in a food-web format to facilitate modeling that emphasizes spatially and temporally paired data. Selenium concentrations are species-specific for fish and taxa-specific for invertebrates to address required specificity for biodynamic dietary modeling. Phytoplankton, zooplankton, and invertebrate densities or biomass are compiled, in addition to fish catches, to help elucidate productivity and identify which groups, taxa, or species are abundant on a seasonal basis. For water quality context, the historical record of selenium concentrations is given, with emphasis on the primary selenium loading site near where the Elk River enters Lake Koocanusa. Spreadsheets with the term "annex" in their file name address a competing toxin, mercury, for fish. Recent high frequency monitoring of selenium concentrations at the international border and at a gaging station below Libby Dam provide a perspective on future selenium data availability. Methodologies are described as federal, provincial, and state agencies transition to a consistent set of protocols to ensure consistency in monitoring for locations on both sides of the border.

This data release and accompanying spreadsheet illustrate the ecosystem scale selenium model for Lake Koocanusa described in USGS Open-File Report 2020-xxxx, "Understanding and Documenting the Scientific Basis of Selenium Ecological Protection in Support of Site-Specific Guidelines Development for Lake Koocanusa, Montana, U.S.A., and British Columbia, Canada." All report sections, equations, and tables referenced in this data release and spreadsheet are from that report, referred to hereafter as “the OFR.” Two models are described in the OFR. Results for several different “runs” of this model with different model input parameters and assumptions are included in this data release. The spreadsheet calculations that produced those results are also included with this data release. Model 1, IFM = Insect-to-fish model, summarized by Eq. 11: protective C(Se)dissolved = tissue guideline/TTFfish /[(TTFinvert1*invert fraction1) + (TTFinvert2*invert fraction2)]/SPM bioavailability fraction/(Kd/1,000). Model2, TFM = Trophic-fish model, summarized by Eq. 12: protective C(Se)dissolved = tissue guideline/TTFfishTL4/TTFfishTL3/[(TTFinvert1*invert fraction1) + (TTFinvert2*invert fraction2)]/SPM bioavailability fraction/(Kd/1,000). Model results are presented for the four representative IFM food webs described in Table 6 of the OFR, and for three representative TFM food webs described in Table 7 of the OFR. “Generic” IFM and TMF modeling spreadsheets (consistent with Tables 8 and 9 of the OFR) are provided that implement the two models such that a user can establish their own modeling assumptions and view the results of the models with those assumptions.Finally, four alternative modeling scenarios and results specifically requested by the Montana Department of Environmental Quality, the cooperator in this work, are also presented here.

This data release and accompanying spreadsheet illustrate the ecosystem scale selenium model for Lake Koocanusa described in USGS Open-File Report 2020-xxxx, "Understanding and Documenting the Scientific Basis of Selenium Ecological Protection in Support of Site-Specific Guidelines Development for Lake Koocanusa, Montana, U.S.A., and British Columbia, Canada." All report sections, equations, and tables referenced in this data release and spreadsheet are from that report, referred to hereafter as “the OFR.” Two models are described in the OFR. Results for several different “runs” of this model with different model input parameters and assumptions are included in this data release. The spreadsheet calculations that produced those results are also included with this data release. Model 1, IFM = Insect-to-fish model, summarized by Eq. 11: protective C(Se)dissolved = tissue guideline/TTFfish /[(TTFinvert1*invert fraction1) + (TTFinvert2*invert fraction2)]/SPM bioavailability fraction/(Kd/1,000). Model2, TFM = Trophic-fish model, summarized by Eq. 12: protective C(Se)dissolved = tissue guideline/TTFfishTL4/TTFfishTL3/[(TTFinvert1*invert fraction1) + (TTFinvert2*invert fraction2)]/SPM bioavailability fraction/(Kd/1,000). Model results are presented for the four representative IFM food webs described in Table 6 of the OFR, and for three representative TFM food webs described in Table 7 of the OFR. “Generic” IFM and TMF modeling spreadsheets (consistent with Tables 8 and 9 of the OFR) are provided that implement the two models such that a user can establish their own modeling assumptions and view the results of the models with those assumptions.Finally, four alternative modeling scenarios and results specifically requested by the Montana Department of Environmental Quality, the cooperator in this work, are also presented here.

Due to declining water levels and increasing salinity in the Salton Sea which may increase the hazards to wildlife, the U.S. Geological Survey and U.S. Bureau of Reclamation are re-evaluating selenium concentrations in the region. As part of this work, selenium concentrations in water and sediment samples and selected other inorganic constituents were compiled from published reports, public databases, and unpublished archives into a tabulated spreadsheet. This spreadsheet represents a rapid synthesis of available data on selenium concentrations in water and sediment in the region surrounding the Salton Sea, however it does not include all data ever published in the region. Additionally, the data compilation was done with an emphasis on selenium concentrations measured after 2005, therefore earlier selenium data may be under-represented.

Due to declining water levels and increasing salinity in the Salton Sea which may increase the hazards to wildlife, the U.S. Geological Survey and U.S. Bureau of Reclamation are re-evaluating selenium concentrations in the region. As part of this work, selenium concentrations in water and sediment samples and selected other inorganic constituents were compiled from published reports, public databases, and unpublished archives into a tabulated spreadsheet. This spreadsheet represents a rapid synthesis of available data on selenium concentrations in water and sediment in the region surrounding the Salton Sea, however it does not include all data ever published in the region. Additionally, the data compilation was done with an emphasis on selenium concentrations measured after 2005, therefore earlier selenium data may be under-represented.

In response to the rapidly evolving conditions at the Salton Sea, with the emergence of both newly formed wetland habitat and increasing hazards to wildlife, the U.S. Bureau of Reclamation and U.S. Geological Survey have funded a re-evaluation of data gaps regarding selenium concentrations in biota the region. As part of this work, selenium concentrations in biological tissue samples were compiled from published reports, public databases, and unpublished archives into a tabulated spreadsheet. Since the California Department of Water Resources summarized selenium biological data in 2005, our compilation efforts focused on the 2005 through 2020 range. The resulting dataset encompasses all records available to us from 1984 to 2020, although we did not find any selenium records after 2017.