Kristin M. Romanok Molly L. Schreiner Paul M. Bradley Kelly L. Smalling Shannon M. Meppelink Carrie E. Givens James L. Gray Michelle L. Hladik Leslie K. Kanagy Rachael F. Lane Keith A. Loftin Clayton D. Raines Daniel L. Tush 20260302 Tabular digital data Denver, CO U.S. Geological Survey Romanok, K.M., Schreiner, M.L., Bradley, P.M., Smalling, K.L., Meppelink, S.M., Givens, C.E., Gray, J.L., Hladik, M.L., Kanagy, L.K., Lane, R.F., Loftin, K.A., Raines, C.D., and Tush, D.L., 2026, Target chemical concentrations of mixed-organic compounds and microbiological indicators in tapwater, Montana, 2024: U.S. Geological Survey data release, https://doi.org/10.5066/P1EQEYVP. https://doi.org/10.5066/P1EQEYVP This data release reports the concentration results for organic compounds (disinfection byproducts [DBP], pesticides, per- and polyfluoroalkyl substances [PFAS], pharmaceuticals and volatile organic compounds [VOC]), cyanotoxins, microbiological indicators, as well as radon-222 analyzed in samples collected from private well and public supply sourced tapwater samples from a community in Montana. A total of 26 samples were collected, plus one quality-control field blank, from 18 residences with private wells and 8 locations who receive their water from public supply sources. Pesticide and DBP compounds were analyzed at the U.S. Geological Survey (USGS) Organic Chemistry Research Laboratory in Sacramento, California; radon-222, PFAS and VOC were analyzed at the USGS National Water Quality Laboratory in Denver, Colorado; pharmaceutical compounds were analyzed at the USGS Organic Geochemistry Research Laboratory in Lawrence, Kansas; microbiological indicators were analyzed at the USGS Michigan Bacteriological Research Laboratory in Lansing, Michigan. Estrogenicity samples were analyzed at the USGS Eastern Ecological Science Center, Leetown, West Virginia. Trace elements and rare earth elements were also analyzed for this study. The results and associated information can be found here: Schreiner, M.L., Romanok, K.M., Bradley, P.M., Smalling, K.L., Meppelink, S.M., McCleskey, R.B., and Roth, D.A., 2024, Concentration results for inorganic constituents in discrete tapwater samples, Montana, 2024: U.S. Geological Survey data release, https://doi.org/10.5066/P1DQ7ZFQ. This project is part of the U.S. Geological Survey (USGS) Ecosystems Mission Area (EMA), Environmental Health Program, Drinking Water and Wastewater Infrastructure Integrated Science Team, Tapwater Exposure Study. Data were collected to provide a 'snapshot' into potential human-health exposures from tapwater sources. Locational information for sites is not provided because of privacy concerns. Tables were generated in Microsoft Excel and should be imported as tab-delimited text (.txt) files to maintain the integrity of values (no loss of leading or trailing zeros). 20240610 20240612 ground condition Complete None planned -116.0600 -104.0400 49.0000 44.3500 Montana ISO 19115 Topic Category geoscientificInformation environment health None tapwater point-of-use exposure environmental health drinking water use organic contaminants radionuclides pesticides disinfection byproducts volatile organic compounds microbiological indicators pharmaceuticals USGS Thesaurus water quality PFAS environmental health (human) drinking water use surface water quality ground water quality USGS Metadata Identifier USGS:682f674dd4be02447781225d Common geographic areas United States Montana None. Please see 'Distribution Info' for details. None. Users are advised to read the dataset's metadata to understand appropriate use and data limitations. Kristin M. Romanok U.S. Geological Survey, New Jersey Water Science Center Hydrologist mailing and physical

3450 Princeton Pike

Suite 110

Lawrenceville New Jersey 08648 United States 609-203-8908 kromanok@usgs.gov This work was funded by the USGS Ecosystems Mission Area, Environmental Health Program. Machine-readable tables were generated in Microsoft Excel, and should be imported as tab-delimited text (.txt) files to maintain the integrity of values (no loss of leading zeros). Michelle L. Hladik Michael J. Focazio Mark Engle 2014 publication Science of The Total Environment vol. 466-467 Amsterdam, Netherlands Elsevier BV Hladik, M.L., Focazio, M.J., and Engle, M., 2014, Discharges of produced waters from oil and gas extraction via wastewater treatment plants are sources of disinfection by-products to receiving streams: Science of The Total Environment, Amsterdam, Netherlands, v. 466-467, p. 1085-1093, accessed June 23, 2025, at https://doi.org/10.1016/j.scitotenv.2013.08.008. https://doi.org/10.1016/j.scitotenv.2013.08.008 Donna L. Rose Mark W. Sandstrom Lucinda K. Murtagh 2016 publication Techniques and Methods 5-B12 Reston, VA U.S. Geological Survey Rose, D.L., Sandstrom, M.W., and Murtagh, L.K., 2016, Determination of heat purgeable and ambient purgeable volatile organic compounds in water by gas chromatography/mass spectrometry: U.S. Geological Survey Techniques and Methods, book 5, chap. B12, 61 p., accessed June 23, 2025, at https://doi.org/10.3133/tm5B12. https://doi.org/10.3133/tm5B12 James L. Gray Leslie K. Kanagy Christopher J. Kanagy Cyrissa A. Anderson 2025 publication Techniques and Methods 5-B13 Reston, VA U.S. Geological Survey Gray, J.L., Kanagy, L.K., Kanagy, C.J., and Anderson, C.A., 2025, Determination of per- and polyfluoroalkyl substances in water by direct injection of matrix-modified centrifuge supernatant and liquid chromatography/tandem mass spectrometry with isotope dilution: U.S. Geological Survey Techniques and Methods, book 5, chap. B13, 127 p., accessed July 8, 2025, at https://doi.org/10.3133/tm5B13. https://doi.org/10.3133/tm5B13 M.S. Gross C.J. Sanders M.D. De Parsia M.L. Hladik 2024 Publication Techniques and Methods 5-A12 Reston, VA U.S. Geological Survey Gross, M.S., Sanders, C.J., De Parsia, M.D., and Hladik, M.L., 2024, Methods of analysis—Determination of pesticides in filtered water and suspended sediment using liquid chromatography- and gas chromatography-tandem mass spectrometry: U.S. Geological Survey Techniques and Methods, book 5, chap. A12, 33 p., accessed June 23, 2025, at https://doi.org/10.3133/tm5A12. https://doi.org/10.3133/tm5A12 Gold Standard Diagnostics 2025 Version 3 Publication Horsham, PA Gold Standard Diagnostics Gold Standard Diagnostics, 2025, ABRAXIS® Glyphosate ELISA microtiter plate enzyme-linked immunosorbent assay for the determination of glyphosate in water samples, Horsham, PA, accessed on July 11, 2025, at https://www.goldstandarddiagnostics.us/media/17823/ifu-21-005-rev-03-abraxis-glyphosate-elisa_500205_500087.pdf. Instructions for the method for analyzing Glyphosate by ELISA can be found within the test kit. https://www.goldstandarddiagnostics.us/media/17823/ifu-21-005-rev-03-abraxis-glyphosate-elisa_500205_500087.pdf ASTM International 1998 Publication West Conshohocken, Pennsylvania ASTM International ASTM International, 1998, Standard test method for radon in drinking water in Annual Book of ASTM Standards, Section 11, Water and Environmental Technology, v. 11.02, Water (I), accessed on July 11, 2025, at https://www.nemi.gov/methods/method_summary/5422/ https://www.nemi.gov/methods/method_summary/5422/ Kristin M. Romanok Dana W. Kolpin Shannon M. Meppelink Maria Argos Juliane B. Brown Michael J. Devito Julie E. Dietze Carrie E. Givens James L. Gray Christopher P. Higgins Michelle L. Hladik Luke R. Iwanowicz Keith A. Loftin R. Blaine McCleskey Carrie A. McDonough Michael T. Meyer Mark J. Strynar Christopher P. Weis Vickie S. Wilson Paul M. Bradley 2018 publication Open-File Report 2018-1098 Reston, VA U.S. Geological Survey Romanok, K.M., Kolpin, D.W., Meppelink, S.M., Argos, M., Brown, J.B., DeVito, M.J., Dietze, J.E., Givens, C.E., Gray, J.L., Higgins, C.P., Hladik, M.L., Iwanowicz, L.R., Loftin, K.A., McCleskey, R.B., McDonough, C.A., Meyer, M.T., Strynar, M.J., Weis, C.P., Wilson, V.S., and Bradley, P.M., 2018, Methods used for the collection and analysis of chemical and biological data for the Tapwater Exposure Study, United States, 2016-17: U.S. Geological Survey Open-File Report 2018-1098, 79 p., accessed July 11, 2025, at https://doi.org/10.3133/ofr20181098. https://doi.org/10.3133/ofr20181098 W.C. Lipps T.E. Baxter E. Braun-Howland 2018a Publication Standard Methods for the Examination of Waste and Wastewater Part 9000 American Public Health Association Press Washington D.C. Lipps, W.C., Baxter, T.E., and Braun-Howland, E., editors, 2018, Standard Methods Committee of the American Public Health Association, American Water Works Association, and Water Environment Federation. 9223 enzyme substrate coliform test: In Standard Methods For the Examination of Water and Wastewater, APHA Press, Washington DC, accessed July 11, 2025, at https://www.standardmethods.org/doi/10.2105/SMWW.2882.194. https://www.standardmethods.org/doi/10.2105/SMWW.2882.194 W.C. Lipps T.E. Baxter E. Braun-Howland 2018b Publication Standard Methods for the Examination of Waste and Wastewater Part 9000 American Public Health Association Press Washington D.C. Lipps, W.C., Baxter, T.E., and Braun-Howland, E., editors, 2018, Standard Methods Committee of the American Public Health Association, American Water Works Association, and Water Environment Federation, 9215 heterotrophic plate count: In Standard Methods For the Examination of Water and Wastewater, APHA Press, Washington DC, accessed July 11, 2025, at https://www.standardmethods.org/doi/full/10.2105/SMWW.2882.188. https://www.standardmethods.org/doi/full/10.2105/SMWW.2882.188 W.C. Lipps T.E. Baxter E. Braun-Howland 2018c Publication Standard Methods for the Examination of Waste and Wastewater Part 9000 American Public Health Association Press Washington D.C. Lipps, W.C., Baxter, T.E., and Braun-Howland, E., editors, 2018, Standard Methods Committee of the American Public Health Association, American Water Works Association, and Water Environment Federation. 9230 fecal enterococci: In Standard Methods For the Examination of Water and Wastewater, APHA Press, Washington DC, accessed July 11, 2025, at https://www.standardmethods.org/doi/10.2105/SMWW.2882.197. https://www.standardmethods.org/doi/10.2105/SMWW.2882.197 Keith A. Loftin Jennifer L. Graham Elizabeth D. Hilborn Sarah C. Lehmann Michael T. Meyer Julie E. Dietze Christopher B. Griffith 2016 Publication Harmful Algae v. 56, p. 77-90 Amsterdam, Netherlands Elsevier B.V. Loftin, K.A, Graham, J.L., Hilborn, E.D., Lehmann, S.C., Meyer, M.T., Dietze, J.E., and Griffith, C.B., 2016, Cyanotoxins in inland lakes of the United States: Occurrence and potential recreational health risks in the EPA National Lakes Assessment 2007: Harmful Algae, v. 56 pp. 77-90, accessed on July 11, 2025, at https://doi.org/10.1016/j.hal.2016.04.001. https://doi.org/10.1016/j.hal.2016.04.001 Jennifer L. Graham Keith A. Loftin Michael T. Meyer Andrew C. Ziegler 2010 Publication Environmental Science and Technology v. 44, no. 19, p. 7361-7368 American Chemical Society Washington, D.C. Graham, J.L., Loftin, K.A., Meyer, M.T., and Ziegler, A.C., 2010, Cyanotoxin mixtures and taste-and-odor compounds in cyanobacterial blooms from the midwestern United States: Environmental Science and Technology, v. 44, no. 19, p. 7361-7368, accessed on May 12, 2015, at https://pubs.acs.org/doi/ipdf/10.1021/es1008938. https://pubs.acs.org/doi/ipdf/10.1021/es1008938 Serena Ciparis Luke R. Iwanowicz J. Reese Voshell 2012 publication Science of The Total Environment v. 414 Amsterdam, Netherlands Elsevier BV Ciparis, S., Iwanowicz, L.R., and Voshell, J.R., 2012, Effects of watershed densities of animal feeding operations on nutrient concentrations and estrogenic activity in agricultural streams: Science of the Total Environment, v. 414, p. 268–276, accessed on July 11, 2025, at https://doi.org/10.1016/j.scitotenv.2011.10.017. https://doi.org/10.1016/j.scitotenv.2011.10.017 John Sanseverino Rakesh K. Gupta Alice C. Layton Stacey S. Patterson Steven A. Ripp Leslie Saidak Michael L. Simpson T. Wayne Schultz Gary S. Sayler 2005 Publication Applied and Environmental Microbiology v. 71, no. 8, p. 4455-4460 Washington, D.C. American Society for Microbiology Sanservino, J., Gupta, R.K., Layton, A.C., Patterson, S.S, Ripp, S.A., Saidak, L., Simpson, M.L., Schultz, T.W., and Sayler, G.S., 2005, Use of saccharomyces cerevisiae BLYES expressing bacterial bioluminescence for rapid, sensitive detection of estrogenic compounds: Applied and Environmental Microbiology, v. 71, no. 8, p. 4455-4460, accessed on May 22, 2025, at https://pmc.ncbi.nlm.nih.gov/articles/PMC1183329/. https://pmc.ncbi.nlm.nih.gov/articles/PMC1183329/ Katharine A. Faber William C.K. Pomerantz James L. Gray Laura E. Hubbard Dana W. Kolpin William A. Arnold 2025 Publication Environmental Science & Technology v. 59, no. 28, p. 14,695-14,706 Washington, D.C. ACS Publications Faber, K.A., Pomerantz, W.C.K., Gray, J.L., Hubbard, L.E., Kolpin, D.W., and Arnold, W.A., 2025, Revealing organofluorine contamination in effluents and surface waters with complementary analytical approaches: fluorine-19 nuclear magnetic resonance spectroscopy (19F-NMR) and liquid chromatography-tandem mass spectrometry (LC-MS/MS): Environmental Sciences & Technology, accessed July 23, 2025, at https://doi.org/10.1021/acs.est.5c05079. https://pubs.acs.org/doi/10.1021/acs.est.5c05079 Concentration results were quality assured through comparison with original data provided by laboratories and evaluated against field blank detections, matrix spikes, and surrogate recoveries where available. Only one organic compound was detected in the field blank; the PFAS compound, 6:2 FTS, at 0.4 nanograms per liter (ng/L). The detection was below the reporting limit and there were no detections in any of the environmental samples. Data is deemed to be accurate as reviewed for logical consistency. Dataset is considered complete for the information presented, as described in the abstract. Users are advised to read the rest of the metadata record for additional details. No formal positional accuracy tests were conducted No formal positional accuracy tests were conducted Twenty-six tapwater samples were collected in Montana in 2024. Eight of these samples were collected from locations served by public supply and 18 were collected from residences using private wells. One quality-control (QC) field blank was collected. Water-quality sample collection methods and laboratory analyses methods are described in Romanok and others (2018). Results prepared by participating laboratories were provided to project staff through electronic transmission, verified, and quality assured by project leads. Data files were compiled and finalized for publication after the data was quality assured. All analytical methods are outlined in MTTW2024_Table2_MethodsInformation_organics.txt included in this data release. See below for analytical details for the pharmaceutical method analyzed at the USGS Organic Geochemistry Research Laboratory (OGRL), Lawrence, Kansas. In 2024, 84 human-use pharmaceutical compounds were analyzed using a research method at the OGRL. Water samples were analyzed by isotope dilution, standard addition, direct-inject ultra-performance liquid chromatography/tandem mass spectrometry (UPLC-MS/MS). Concentration results are reported in nanograms per liter (ng/L). The method reporting limit for the 84 analytes ranged from 1 to 100 ng/L depending on the sensitivity of each compound. See MTTW2024_Table2_MethodsInformation_organics.txt for a list of those compounds. Quality was assured for all samples analyzed by this method included laboratory method blanks, check standard (spike) analysis, laboratory duplicates, and matrix spikes. A summary of these QC results is below. Water samples were collected in amber glass bottles with Teflon lined caps, packed with ice, and shipped overnight to OGRL. Samples analyzed after June 2024 were collected with the addition of a dechlorinating agent (61.5 milligrams (mg) of ascorbic acid added to 123 milliliters (mL) of sample). After arrival at OGRL, samples were either processed or stored frozen (-20 degrees Celsius (⁰C)) until processing. Samples, standards, continuous calibration verification standards (CCVs), and blanks were prepared for analysis by adding 4 mL of sample or water to a vial, spiking it with a mix of surrogate internal standards, and after June 2024, 5 mg of ammonium formate also was added, then filtering with a 0.2-micron water-wettable polytetrafluoroethylene (ww-PTFE) syringe filter. Samples, standards, CCVs, and blanks were prepared for analysis by adding 4 mL of either sample or water to a vial, followed by the addition of the surrogate internal standards mix; beginning in June 2024, 5 mg of ammonium formate also was incorporated into the preparation, and then the mixture was filtered with a 0.2-micron ww-PTFE syringe filter. For each sample, a standard addition sample was created by spiking a laboratory duplicate with 100 parts per trillion (ppt) of the analyte mix. Standard curve, CCVs, and blank samples were prepared in type I water (18.2 megaohm-cm (MΩ-centimeter0), less than or equal to 3 parts per billion (ppb) total organic carbon (TOC) and processed in the same manner as the environmental water samples. The standard curve, samples, laboratory duplicate samples, laboratory blank samples, and CCVs were analyzed with a Water H-Class Bio UPLC and a Waters Xevo TQ-XS mass spectrometer. Samples were injected three times to be analyzed with different methods for each subset of compounds. Two of the methods performed chromatographic separation on a Waters Acquity BEH C18 1.7 micrometer (μm), 150x2.1 millimeter (mm) column using either a 12-minute gradient consisting of 0.1 percent acetic acid in water and methanol or a 31-minute gradient consisting of 0.1 percent formic acid and a 50/50 mixture of acetonitrile and methanol with 0.1 percent formic acid. The third method initially used a Waters Acquity HSS PFP 1.8 um, 2.1 x 100 mm column with a 12.5-minute gradient consisting of 20 millimolar (mM) ammonium formate in water with 0.1 percent formic acid and a 50/50 mixture of acetonitrile and methanol with 0.1 percent formic acid. In June 2024, the column was replaced with a Waters Atlantis dc18 3 μm, 150x3 mm column. For mass spectrometry detection of the compounds, positive and negative (butalbital, gemfibrozil, hydrochlorothiazide, and topiramate) mode electrospray ionization (ESI) were used with multiple reaction monitoring (MRM). Compounds were identified based on the retention times and when possible the ratio of two MRM transitions being within plus or minus 25 percent (a small number of compounds only had one usable fragment). A linear 1/x weighting was applied to the calibration curve and detected compounds were quantitated using standard addition method to account for any instrumental sample matrix variability. To meet OGRL quality control specifications, environmental samples and duplicates were not to exceed a 20 percent difference, the target matrix spike recovery range was within 80-120 percent for analytes with matching surrogate internal standards, and the check standard accuracy was within 80-120 percent. Ten laboratory method blanks were analyzed between February 2 and August 25, 2024, on 84 pharmaceutical compounds; no compounds were detected above their reporting limits. Eight check standards were conducted at 5 ng/L of the 84 pharmaceutical compounds between February 2 and March 30, 2024. Median percent accuracies ranged from 82 to 116 percent. The interquartile range (IQR) was from 1.3 to 56 percent around the median. Six laboratory check standards were conducted at 20 ng/L between July 24 and September 23, 2024; median percent accuracies ranged from 80.7 to 115 percent. The IQR was between 0.44 to 17.1 percent. Eight laboratory check standards also were conducted at 50 ng/L for the same compounds. Median percent accuracies ranged from 82.8 to 112 percent. The IQR was between 1.4 to 51.7 percent around the median. Finally, six check standards were analyzed at 200 ng/L, the median percent accuracies ranged from 87.7 to 118 percent, with the IQR ranging from 0.78 to 21.4 percent. Seven laboratory duplicate samples were analyzed between January and March, 2024. Of these samples, non-detected and detected results matched in 100 percent in the associated duplicate sample. Where concentrations were detected in the environmental sample, the accuracy (calculated as absolute relative percent difference) of the concentration results ranged from 0-16 percent (median, 1.5 percent). One to seven (analyte dependent) laboratory matrix spike samples were analyzed between February 2 and September 23, 2024. Samples were spiked with 100 ng/L of a known analyte to determine any matrix interference within the environmental sample. Spike recoveries ranged from 0-151 percent (median, 103 percent). Very low (below 10 percent) and very high (greater than 125 percent) likely resulted from chlorine impacts from chlorinated tapwater samples. In the next phase of the method development, ascorbic acid will be added to the samples to improve recoveries. Analytes with high recoveries were tamoxifen (92-151 percent; median, 110 percent) and verapamil (94-131 percent; median, 105 percent); ranitidine (0-109 percent, median, 101 percent) and acetaminophen (10-121 percent; median, 104 percent) were the two compounds exhibiting very low recoveries. Any reported concentrations where the recoveries were above or below 80-120 percent, were corrected appropriately by the analyst. PFAS analysis for this study was adapted from Gray and others, 2025, to include an on-line solid-phase-extraction step prior to liquid chromatography-tandem mass spectrometry. Additional details for the PFAS method used in this study can be found in Faber and others, 2025. Quality control data for this method can be found in MTTW2024_Table4b_QC_PFAS_Surrogates.txt and MTTW2024_Table4c_QC_FieldBlanks.txt in this data release. References cited: Gray, J.L., Kanagy, L.K., Kanagy, C.J., and Anderson, C.A., 2025, Determination of per- and polyfluoroalkyl substances in water by direct injection of matrix-modified centrifuge supernatant and liquid chromatography/tandem mass spectrometry with isotope dilution: U.S. Geological Survey Techniques and Methods, book 5, chap. B13, 127 p., accessed July 22, 2025, at https://doi.org/10.3133/tm5B13. Faber, K.A., Pomerantz, W.C.K., Gray, J.L., Hubbard, L.E., Kolpin, D.W., and Arnold, W.A., 2025, Revealing organofluorine contamination in effluents and surface waters with complementary analytical approaches: fluorine-19 nuclear magnetic resonance spectroscopy (19F-NMR) and liquid chromatography-tandem mass spectrometry (LC-MS/MS): Environmental Sciences and Technology, accessed July 23, 2025, at https://doi.org/10.1021/acs.est.5c05079. Romanok, K.M., Kolpin, D.W., Meppelink, S.M., Argos, M., Brown, J.B., DeVito, M.J., Dietze, J.E., Givens, C.E., Gray, J.L., Higgins, C.P., Hladik, M.L., Iwanowicz, L.R., Loftin, K.A., McCleskey, R.B., McDonough, C.A., Meyer, M.T., Strynar, M.J., Weis, C.P., Wilson, V.S., and Bradley, P.M., 2018, Methods used for the collection and analysis of chemical and biological data for the Tapwater Exposure Study, United States, 2016-17: U.S. Geological Survey Open-File Report 2018-1098, 79 p., accessed July 22, 2025, at https://doi.org/10.3133/ofr20181098. 2024 MTTW2024_Table1_SiteInformation.txt Table 1. Site information for samples collected by the U.S. Geological Survey (USGS) Environmental Health Program, for the Tapwater Exposure Study, Montana, 2024. U.S. Geological Survey USGS_station_number Station number U.S. Geological Survey U.S. Geological Survey station number USGS_station_name Station identifier U.S. Geological Survey U.S. Geological Survey station identifier Sample_date_yyyymmdd Date of sampling U.S. Geological Survey 20240610 20240612 Date; yyyy, year; mm, month; dd, day Sample_time_HHMM Time of sample collection U.S. Geological Survey 0750 1340 Time, HH,military-hour; MM, minute Site_type Description of water-quality sample source water U.S. Geological Survey Public supply Tapwater sourced from a public supplier U.S. Geological Survey Private well Tapwater sourced from a privately-owned groundwater well U.S. Geological Survey Field blank Field-collected quality-control sample U.S. Geological Survey MTTW2024_Table2_MethodsInformation_organics.txt Table 2. Method information for organic compounds analyzed in samples collected by the U.S. Geological Survey (USGS) Environmental Health Program, for the Tapwater Exposure study, Montana, 2024. U.S. Geological Survey Parameter_name List of compounds analyzed for this study U.S. Geological Survey Organic compounds analyzed for this study CASRN Chemical Abstract Services Registry Numbers (CASRNs) for associated parameter listed in column 1 U.S. Geological Survey -- Information not available U.S. Geological Survey CASRN definitions are available at https://commonchemistry.cas.org/?_ga=2.268858289.111681852.1682955224-1720481698.1682955224, accessed onaccessed on July 11, 2025. Analyzing_laboratory Laboratory that performed analysis of compound listed in column 1 U.S. Geological Survey NWQL USGS National Water Quality Laboratory, Denver, Colorado U.S. Geological Survey OCRL USGS Organic Chemistry Research Laboratory, Sacramento, California U.S. Geological Survey OGRL USGS Organic Geochemistry Research Laboratory, Lawrence, Kansas U.S. Geological Survey MIBaRL USGS Michigan Bacteriological Research Laboratory, Lansing, Michigan U.S. Geological Survey FMBL USGS Functional and Molecular Bioassay Laboratory, Kearneysville, West Virginia U.S. Geological Survey Common_primary_use_group General description of parameter listed in column 1 U.S. Geological Survey Description of type of parameter listed in column 1. Method Methods used in laboratory analyses U.S. Geological Survey ELISA Enzyme linked immunosorbent assay U.S. Geological Survey LC-MS/MS Liquid chromatography-tandem mass spectrometry U.S. Geological Survey Online SPE, LC-MS/MS Online solid phase extraction, liquid chromatography-tandem mass spectrometry U.S. Geological Survey GC-MS/MS Gas chromatography-tandem mass spectrometry U.S. Geological Survey GC-MS Gas chromatography-mass spectrometry U.S. Geological Survey IDEXX Colilert IDEXX Colilert kit for Escherichia Coli and coliforms from IDEXX Laboratories, Westbrook, Maine U.S. Geological Survey IDEXX SimPlate IDEXX SimPlate for HPC (heterotrophic plate counts) from IDEXX Laboratories, Westbrook, Maine U.S. Geological Survey IDEXX Enterolert IDEXX kit for enterococci from IDEXX Laboratories, Westbrook, Maine U.S. Geological Survey Scintillation Scintiallation counting U.S. Geological Survey T47KBluc Estrogen responsive in vitro cell bioassay U.S. Geological Survey Detection_limit Lowest concentration compound is detected U.S. Geological Survey -- Information not available U.S. Geological Survey Lowest concentration at which compound from column 1 would be detected, as per method. Reporting_limit Lowest concentration compound is reported U.S. Geological Survey Lowest concentration at which compound from column 1 would be reported, as per method. Reporting limit reflected in MTTW2024_Table3a_Results_organics.txt, which are established by the analyzing laboratory and may have been adjusted (increased) as a result of internal laboratory quality-control issues, such as poor surrogate recovery response. Method_of_quantitation Method used to determine reporting level U.S. Geological Survey MDL Method detection level U.S. Geological Survey MRL Minimum reporting level U.S. Geological Survey RLDQC Reporting limit by DQCALC program used by the NWQL U.S. Geological Survey Count Count of visible colonies U.S. Geological Survey LOQ Limit of quantitation U.S. Geological Survey IRL Interim reporting level U.S. Geological Survey SSLC sample-specific critical level U.S. Geological Survey Units_of_measurement Units of measurement for which results are reported U.S. Geological Survey ug/L Micrograms per liter U.S. Geological Survey ng/L Nanograms per liter U.S. Geological Survey Estrogen equivalents, ng/L Estrogen equivalents, nanograms per liter U.S. Geological Survey MPN/100mL Most probable number per 100 milliliters U.S. Geological Survey pCi/L PicoCuries per liter U.S. Geological Survey Method_citation References for laboratory analyses U.S. Geological Survey Refer to Cross Reference section of this metadata file for citation information details. MTTW2024_Table3a_Results_organics.txt Table 3a. Concentration results for organic compounds analyzed in samples collected by the U.S. Geological Survey (USGS) Environmental Health Program, for the Tapwater Exposure study, Montana, 2024. U.S. Geological Survey Station_name Station identifier U.S. Geological Survey See MTTW2024_Table1_SiteInformation.txt for more information. Sample_date_yyyymmdd Date of sampling U.S. Geological Survey 20240610 20240612 Date; yyyy, year; mm, month; dd, day Sample_time_HHMM Time of sample collection U.S. Geological Survey 0750 1340 Time, HH,military-hour; MM, minute Site_type Description of water-quality sample source water U.S. Geological Survey Public supply Tapwater sourced from a public supplier U.S. Geological Survey Private well Tapwater sourced from a privately-owned groundwater well U.S. Geological Survey Parameter_name List of compounds analyzed for this study U.S. Geological Survey Refer to MTTW2024_Table2_MethodsInformation_organics.txt for additional analytical details. Remark_and_result Remark code and final result in units listed in column 7 (Units of measurement) U.S. Geological Survey u unable to determine, matrix interference U.S. Geological Survey E Estimated U.S. Geological Survey Less than sign Value is less than the listed reporting limit (not detected) U.S. Geological Survey Units_of_measurement Units of measurement for which results are reported U.S. Geological Survey pCi/L PicoCuries per liter U.S. Geological Survey ug/L Micrograms per liter U.S. Geological Survey ng/L Nanograms per liter U.S. Geological Survey Reporting_level Lowest concentration compound is reported U.S. Geological Survey Lowest concentration at which compound from column 5 would be reported, as per method. Reporting level reflected in MTTW2024_Table3a_Results_organics.txt, which are established by the analyzing laboratory and may have been adjusted (increased) as a result of internal laboratory quality-control issues, such as poor surrogate recovery response. Results below the reporting level are reported at analysts discretion. Analyzing_laboratory Laboratory that performed analysis of compound listed in column 6 (parameter name). Refer to MTTW2024_Table2_MethodsInformation_organics.txt for additional analytical details. U.S. Geological Survey NWQL USGS National Water Quality Laboratory, Denver, Colorado U.S. Geological Survey OCRL USGS Organic Chemistry Research Laboratory, Sacramento, California U.S. Geological Survey OGRL USGS Organic Geochemistry Research Laboratory, Lawrence, Kansas U.S. Geological Survey MTTW2024_Table3b_Results_Microbiology.txt Table 3b. Microbiological results for samples collected as part of the U.S. Geological Survey (USGS), Environmental Health Program, for the Tapwater Exposure Study, Montana, 2024. U.S. Geological Survey Station_name Station identifier U.S. Geological Survey See MTTW2024_Table1_SiteInformation for more information. Sample_date_yyyymmdd Date of sample collection U.S. Geological Survey 20240610 20240612 Date; yyyy, year; mm, month; dd, day Sample_time_HHMM Time of sample collection U.S. Geological Survey 0750 1340 Time, HH,military-hour; MM, minute Site_type Description of water-quality sample source water U.S. Geological Survey Public supply Tapwater sourced from a public supplier U.S. Geological Survey Private well Tapwater sourced from a privately-owned groundwater well U.S. Geological Survey Field blank Field collected quality-control sample U.S. Geological Survey HPC_MPN_per_100_mL Heterotrophic Plate Count (HPC), most probable number (MPN) per 100 milliliters U.S. Geological Survey Less than sign Value is less than the listed reporting limit (not detected) U.S. Geological Survey Greater than sign Value is above upper limit of quantitation. U.S. Geological Survey Less than 20 Greater than 7,380 Most probable number per 100 milliliters Total_coliforms_MPN_per_100_mL Total coliforms, most probable number (MPN) per 100 milliliters U.S. Geological Survey Less than sign Value is less than the listed reporting limit (not detected) U.S. Geological Survey Less than 1.0 12 Most probable number per 100 milliliters E.coli_MPN_per_100_mL Escherichia coli, most probable number (MPN) per 100 milliliters U.S. Geological Survey Less than sign Value is less than the listed reporting limit (not detected) U.S. Geological Survey Less than 1.0 2 Most probable number per 100 milliliters Enterococci_MPN_per_100_mL Enterococci, most probable number per 100 milliliters U.S. Geological Survey Less than sign Value is less than the listed reporting limit (not detected) U.S. Geological Survey Less than 1.0 Less than 1.0 Most probable number per 100 milliliters MTTW2024_Table3c_Results_Cyanotoxins.txt Table 3c. Concentration results for cyanotoxin compounds, in micrograms per liter, analyzed for the U.S. Geological Survey (USGS), Environmental Health Program, for the Tapwater Exposure Study, Montana, 2024. U.S. Geological Survey Station_name Station identifier U.S. Geological Survey See MTTW2024_Table1_SiteInformation.txt for more information. Sample_date_yyyymmdd Date of sample collection U.S. Geological Survey 20240610 20240612 Date, yyyy, year; mm, month; dd, day Sample_time_HHMM Time of sample collection U.S. Geological Survey 0750 1341 Time, HH,military-hour; MM, minute Site_type Description of water-quality sample source water U.S. Geological Survey Private well Tapwater sourced from a privately-owned groundwater well U.S. Geological Survey Public supply Tapwater sourced from a public supplier U.S. Geological Survey Public supply (replicate) Laboratory replicate of public supply sample U.S. Geological Survey Saxitoxin Saxitoxin concentration results, in micrograms per liter (ug/L) U.S. Geological Survey Less than sign Value is less than the listed reporting limit (not detected) U.S. Geological Survey -- Not anaylzed U.S. Geological Survey Less than 0.02 Less than 0.02 Micrograms per liter Cylindrospermopsin Cylindrospermopsin concentration results, in micrograms per liter (ug/L) U.S. Geological Survey Less than sign Value is less than the listed reporting limit (not detected) U.S. Geological Survey -- Not analyzed U.S. Geological Survey Less than 0.05 Less than 0.05 Micrograms per liter Anatoxin_a Anatoxin-a concentration results, in micrograms per liter (ug/L) U.S. Geological Survey Less than sign Value is less than the listed reporting limit (not detected) U.S. Geological Survey Less than 0.15 0.18 Micrograms per liter Microcystin Microcystin concentration results, in micrograms per liter (ug/L) U.S. Geological Survey Less than sign Value is less than the listed reporting limit (not detected) U.S. Geological Survey -- Not analyzed U.S. Geological Survey Less than 0.10 Less than 0.10 Micrograms per liter MTTW2024_Table3d_Results_E2Eq.txt Table 3d. Mammalian estrogen receptor (ER) activity, reported in nanogram equivalents per liter (ng/L) of standard steroid hormone (E2Eq) analyzed in samples collected by the U.S. Geological Survey (USGS) Environmental Health Program, for the Tapwater Exposure study, Montana, 2024. U.S. Geological Survey Station_name Station identifier U.S. Geological Survey See MTTW2024_Table1_SiteInformation.txt for more information. Sample_date_yyyymmdd Date of sampling U.S. Geological Survey 20240610 20240612 Date; yyyy, year; mm, month; dd, day Sample_time_HHMM Time of sample collection U.S. Geological Survey 0750 1340 Time, HH, military-hour; MM, minute Site_type Description of water-quality sample source water U.S. Geological Survey Public supply Tapwater sourced from a public supplier U.S. Geological Survey Private well Tapwater sourced from a privately-owned groundwater well U.S. Geological Survey ER_activity Estrogen receptor activity (equivalent) by BLYES method. BLYES, Bioluminescent Yeast Estrogen Assay. U.S. Geological Survey BD below method detection limit U.S. Geological Survey ND Not determined U.S. Geological Survey MTTW2024_Table4a_QC_SurrogateSummary_organics.txt Table 4a. Quality control surrogate and internal dilution standard summary statistics (percent recoveries) for the U.S. Geological Survey (USGS) Environmental Health Program, for the Tapwater Exposure Study, Montana, 2024. U.S. Geological Survey Analyzing_laboratory Laboratory that performed analysis of compounds listed in column 2. U.S. Geological Survey NWQL USGS National Water Quality Laboratory, Denver, Colorado U.S. Geological Survey OCRL USGS Organic Chemistry Research Laboratory, Sacramento, California U.S. Geological Survey Surrogate_or_internal_dilution_standard Surrogate or internal dilution standard used for internal laboratory quality control. U.S. Geological Survey Surrogate or internal dilution standard used for internal laboratory quality control. Minimum Minimum percent recovery for listed surrogate of internal dilution standard. U.S. Geological Survey 59.8 108 Percent 25th_percentile Interquartile range for listed surrogate of internal dilution standard: 25th percentile. U.S. Geological Survey 74.0 111 Percentile Median Median percent recovery for listed surrogate of internal dilution standard. U.S. Geological Survey 79.0 116 Percent 75th_percentile Interquartile range for listed surrogate of internal dilution standard: 75th percentile. U.S. Geological Survey 80.7 122 Percentile Maximum Maximum percent recovery for listed surrogate of internal dilution standard. U.S. Geological Survey 84.4 133 Percent MTTW2024_Table4b_QC_PFAS_Surrogates.txt Table 4b. Quality control surrogate and (or) internal dilution standard results, in percent recovery, for the U.S. Geological Survey (USGS) Environmental Health Program, for the Tapwater Exposure Study, Montana, 2024. U.S. Geological Survey Station_name Station identifier U.S. Geological Survey See MTTW2024_Table1_SiteInformation.txt for more information. Sample_date_yyyymmdd Date of sampling U.S. Geological Survey 20240610 20240612 Date: yyyy, year; mm, month; dd, day Site_type Description of water-quality sample source water U.S. Geological Survey Public supply Tapwater sourced from a public supplier U.S. Geological Survey Private well Tapwater sourced from a privately-owned groundwater well U.S. Geological Survey Columns 4-34 Percent recovery results for quality control surrogate and (or) internal dilution standards, corresponding to headers: PFBA_13C4; PFPeA_13C5; PFBS_13C3; 4:2FTS_13C2D4; PFHxA_13C5; 6:2_PAP_13C2; GenX_13C3; PFHpA_13C4; PFHxS_13C3; FHUEA_13C2; 6:2FTS_13C2D4; PFOA_13C8; 8:2_PAP_13C2; PFNA_13C9; FOSA_13C8; PFOS_13C8; FOUEA_13C2; 8:2FTS_13C2; 8:2FTS_13C2D4; PFDA_13C6; N_MeFOSAA_D3; N_MeFOSA_D3; N_EtFOSAA_D5; PFUnDA_13C7; FDUEA_13C2; N_EtFOSA_D5; 10:2FTS_13C2D4; PFDoA_13C2; 6:2_diPAP_13C4; PFTeDA_13C2; 8:2_diPAP_13C4 U.S. Geological Survey Quality control surrogates and (or) internal dilution standards for PFAS analyzed using online solid phase extraction and liquid chromatography/tandem mass spectrometry. See MTTW2024_Table2_MethodsInformation_organics.txt for compound details. MTTW2024_Table4c_QC_FieldBlanks.txt Table 4c. Concentrations of compounds detecte in field blanks collected by the U.S. Geological Survey (USGS) Environmental Health Program, for the Tapwater Exposure study, Montana, 2024. U.S. Geological Survey Station_name Station identifier U.S. Geological Survey See MTTW2024_Table1_SiteInformation.txt for more information. Sample_date_yyyymmdd Date of sampling U.S. Geological Survey 20240612 20240612 Date; yyyy, year; mm, month; dd, day Sample_time_HHMM Time of sample collection U.S. Geological Survey 0820 0820 Time, HH, military-hour; MM, minute Parameter_name List of compounds analyzed for this study U.S. Geological Survey Refer to MTTW2024_Table2_MethodsInformation_organics.txt for additional compound details. Remark_and_result Remark code and final result in units listed in column 6 (Units of measurement) U.S. Geological Survey Refer to MTTW2024_Table2_MethodsInformation_organics.txt for additional compound details. Units_of_measurement Units of measurement for which results are reported U.S. Geological Survey ng/L Nanograms per liter U.S. Geological Survey Reporting_level Lowest concentration compound is reported U.S. Geological Survey Lowest concentration at which compound from column 6 would be reported, as per method. Reporting level reflected in MTTW2024_Table3a_Results_organics.txt, which are established by the analyzing laboratory and may have been adjusted (increased) as a result of internal laboratory quality-control issues, such as poor surrogate recovery response. Results below the reporting level are reported at analysts discretion. Analyzing_laboratory Laboratory that performed analysis of compound listed in column 6 (parameter name). Refer to MTTW2024_Table2_MethodsInformation_organics.txt for additional analytical details. U.S. Geological Survey NWQL USGS National Water Quality Laboratory, Denver, Colorado U.S. Geological Survey GS ScienceBase U.S. Geological Survey mailing address

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