Matthew S. Varonka Aaron M. Jubb Bonnie McDevitt Jenna L. Shelton Elliott P. Barnhart Denise M. Akob Isabelle M. Cozzarelli 20250718 tabular digital data Reston, VA U.S. Geological Survey https://doi.org/10.5066/P13SQVJA Per- and polyfluoroaklyl substances (PFAS) of are of interest due to their persistence and ubiquity in the environment and their potential health and environmental effects. While these compounds have been well studied in the past 10 years, little is known about PFAS in oil and gas produced waters, which are voluminous and have the potential to impact the environment through surficial spills and groundwater contamination. This study aims to provide the first known analyses of PFAS in oil and gas produced waters. Samples including hydraulic fracturing fluid, water from two input ponds used to mix fracture fluid, and produced water from three wells in the Niobrara formation in the Denver Basin were collected and analyzed for PFAS. Time series samples from the three wells were collected from day 1 of production through approximately one year. For the day 1 production samples from the time series wells, both targeted PFAS using EPA Draft 1633 method and total oxidizable precursors (TOP) analyses were performed. Data were collected to determine if per- and polyfluoroaklyl substances (PFAS) are present in produced water samples from petroleum wells in the Denver Basin. The file contains data available in comma separated value (.csv) file format. The user must have software capable of opening and viewing a .csv file. 20230518 20240527 ground condition Complete None planned -105.4797 -102.0630 42.1308 38.4019 ISO 19115 Topic Category environment geoscientificInformation USGS Thesaurus (https://apps.usgs.gov/thesaurus/) PFAS produced water oil resources natural gas resources petroleum water quality water chemistry USGS Metadata Identifier USGS:67aa13f4d34e329fb204345e Common geographic areas (https://apps.usgs.gov/thesaurus/cga/) Colorado National Geologic Map Database Geolex - AAPG Geologic Provinces (https://ngmdb.usgs.gov/Geolex/stratres/provinces) Denver Basin None. Please see 'Distribution Info' for details. None. Users are advised to read the dataset's metadata thoroughly to understand appropriate use and data limitations. Matthew S Varonka U.S. Geological Survey, Northeast Region Research Chemist mailing and physical

National Center, John W Powell FB

Reston VA 20192 703-648-6412 mvaronka@usgs.gov Amanda S. Herzberg Jenna L. Shelton Aaron M. Jubb Jessica M. Chenault Bonnie McDevitt Kaela K. Amundson Michael J. Wilkins Elliott P. Barnhart Christina A. DeVera Madalyn A. Blondes Glenn D. Jolly 20241001 tabular digital data Reston, Virginia U.S. Geological Survey https://doi.org/10.5066/P14CRSQQ Aaron M. Jubb Jenna L. Shelton Bonnie McDevitt Kaela K. Amundson Amanda S. Herzberg Jessica M. Chenault Andrew L. Masterson Matthew S. Varonka Glenn D. Jolly Christina A. DeVera Elliott Barnhart Michael J. Wilkins Madalyn S. Blondes 202412 publication Science of The Total Environment vol. 955 n/a Elsevier BV 176845 https://doi.org/10.1016/j.scitotenv.2024.176845 Quality control measures include matrix spikes, method blank, and field blank analyses. See process step for more information. NA NA NA NA Water samples including hydraulic fracturing fluid, two input ponds used for mixing fracture fluid, and produced water from three recently completed and fractured wells were collected in 2018 - 2019. Samples were collected and filtered (= 0.45 um) in the field and shipped to the U.S. Geological Survey Brine Research Instrumentation and Experimental Laboratory in Reston, Virginia. In 2023, splits of a subset of samples were sent to the SGS-Orlando laboratory (LABORATORY = SGS-Orlando, Orlando, FL, USA) for per- and polyfluoroalkyl substances (PFAS) analysis via the EPA Draft 1633 method. In 2024, splits of a subset of samples were sent to the SGS-AXYS laboratory (LABORATORY = SGS-AXYS, Sidney, BC, Canada) for PFAS analysis via SGS AXYS METHOD MLA-110 Rev 02 (equivalent to EPA Draft 1633). Three samples were also screened using the total oxidizable precursor (TOP) assay, which subjects the sample to hydoxyl radical oxidation to convert unknown, oxidizable PFAS to perfluoroalkyl acids (PFAAs) which are then detected using LC-MS/MS. 20240527 Production data was sourced from the S and P Global Commodity Insights US Well History and Production database. S and P Global Commodity Insights (2023). US Well History and Production; database available from S and P Global Insights spglobal.com/commodityinsights 20240930 PWPFAS_RESULTS.csv Comma Separated Value (CSV) file containing data. Data table contains sample information and measured per- and polyfluoroalkyl substance concentrations. Producer Defined SAMPLE_ID Unique sample identifier. Producer Defined Unique sample identifier. WELL_ID Description of time series well or alternate sampling location. Producer Defined FIELD BLANK Field blank collected with samples. Producer defined FRACK FLUID Sample of hydraulic fracturing fluid collected with time series samples. Producer defined JMDJ INPUT FLUIDS POND 1 Sample of an input pond used for mixing hydraulic fracturing fluids. Producer defined JMDJ INPUT FLUIDS POND 2 Sample of an input pond used for mixing hydraulic fracturing fluids. Producer defined NWTS-3 Well associated with time series samples. Total vertical depth is approximately 6,300' and the lateral length is approximately 9,800'. Well was fractured using a crosslinked gel hydraulic fracturing fluid. Producer defined NWTS-1 Well associated with time series samples. Total vertical depth is approximately 6,300' and the lateral length is approximately 4,900'. Well was fractured using a slickwater hydraulic fracturing fluid. Producer defined NWTS-2 Well associated with time series samples. Total vertical depth is approximately 6,300' and the lateral length is approximately 9,800'. Well was fractured using a crosslinked gel hydraulic fracturing fluid. Producer defined PROD_DAYS Number of days the time series well had been producing. Producer Defined NA No Data Producer defined 1 368 days ANALYSIS_DATE Date of analysis in YYYY-MM-DD format. Producer Defined 2023-05-18 Date of analysis. Producer defined 2024-04-07 Date of analysis. Producer defined 2024-05-27 Date of analysis. Producer defined ANALYSIS Type of per- and polyfluoroalkyl substances (PFAS) analysis. Producer Defined FC_LC Targeted analysis by EPA Draft 1633 method. Producer defined POSTOXIDATION Total oxidizable precursor (TOP) analysis. Producer defined COMPOUND Compound abbreviation. Producer Defined Compound abbreviations defined as follows: PFBA = Perfluorobutanoic acid PFPeA = Perfluoropentanoic acid PFHxA = Perfluorohexanoic acid PFHpA = Perfluoroheptanoic acid PFOA = Perfluorooctanoic acid PFNA = Perfluorononaoic acid PFDA = Perfluorodecanoic acid PFUnA = Perfluoroundecanoic acid PFDoA = Perfluorododecanoic acid PFTrDA = Perfluorotridecanoic acid PFTeDA = Perfluorotetradecanoic acid PFBS = Perfluorobutanesulfonic acid PFPeS = Perfluoropentanesulfonic acid PFHxS = Perfluorohexanesulfonic acid PFHpS = Perfluoroheptanesulfonic acid PFOS = Perfluorooctanesulfonic acid PFNS = Perfluorononanesulfonic acid PFDS = Perfluorodecanesulfonic acid PFDoS = Perfluorododecanesulfonic acid 4:2 FTS = 4:2 Fluorotelomer sulfonate 6:2 FTS = 6:2 Fluorotelomer sulfonate 8:2 FTS = 8:2 Fluorotelomer sulfonate PFOSA = Perfluorooctanesulfonamide N-MeFOSA = N-Methylperfluorooctanesulfonamide N-EtFOSA = N-Ethylperfluorooctanesulfonamide MeFOSAA = N-Methylperfluorooctanesulfonamidoacetic acid EtFOSAA = N-Ethylperfluorooctanesulfonamidoacetic acid N-MeFOSE = N-Methylperfluorooctanesulfonamidoethanol N-EtFOSE = N-Ethylperfluorooctanesulfonamidoethanol HFPO-DA = Hexafluoropropylene oxide-dimer acid ADONA = 4,8-Dioxa-3H-perfluorononanoic acid PFMPA = Perfluoro-3-methoxypropanoic acid PFMBA = Perfluoro-4-methoxybutanoic acid NFDHA = Nonafluoro-3,6-dioxaheptanoic acid 9Cl-PF3ONS = 9-Chlorohexadecafluoro-3-oxanone-1-sulfonic Acid 11Cl-PF3OUdS = 11-Chloroeicosafluoro-3-oxaundecane-1-sulfonic acid PFEESA = Perfluoro(2-ethoxyethane)sulphonic acid 3:3 FTCA = 3:3 Fluorotelomer carboxylate 5:3 FTCA = 5:3 Fluorotelomer carboxylate 7:3 FTCA = 7:3 Fluorotelomer carboxylate CAS_NO_1 First Chemical Abstract Service number. There can be more than one CAS number associated with each compound due to the ionized and non-ionized forms. Producer Defined NA No Data Producer defined Values are Chemical Abstract Service numbers. CAS_NO_2 Second Chemical Abstract Service number. There can be more than one CAS number associated with each compound due to the ionized and non-ionized forms. Producer Defined NA No Data Producer defined Values are Chemical Abstract Service numbers. LAB_FLAG Flags provided by the laboratories to denote qualifiers on the data. Producer Defined NA No Flags Producer defined J J = Result is above the minimum detection limit, but below the limit of quantitation. Producer defined R J R = Peak detected but did not meet quantification criteria, result reported represents the estimated maximum possible concentration. J = Result is above the minimum detection limit, but below the limit of quantitation. Producer defined U U = Analyte not detected. Producer defined B J B = Analyte found in sample and the associated blank. J = Result is above the minimum detection limit, but below the limit of quantitation. Producer defined V V = Surrogate recovery is not within method/contract control limits. Producer defined CONC_FOUND Concentration of individual per- and polyfluoroalkyl substances (PFAS) found in nanograms per liter (ng/L) Producer Defined ND Not detected. Producer defined 0.543 28.4 ng/L DETECTION_LIMIT Detection limit of the analyte in nanograms per liter (ng/L). Producer Defined NA No Data Producer defined 0.359 77.5 ng/L UNIT Units of CONC_FOUND and DETECTION_LIMIT. Producer Defined ng/L nanograms per liter Producer defined SAMPLE_SIZE Sample volume extracted for per- and polyfluoroalkyl substances (PFAS) analysis in liters (L). Producer Defined 0.0645 0.445 L SAMPLE_SIZE_UNIT Units for SAMPLE_SIZE. Producer Defined L liters Producer defined MATRIX Matrix of the sample. Producer Defined AQUEOUS Samples were in an aqueous matrix. Producer defined LABORATORY Contract laboratory that performed the per- and polyfluoroalkyl substances analyses. Producer Defined SGS-Orlando SGS-Orlando laboratory in Orlando, FL, USA. Producer defined SGS-AXYS SGS-AXYS laboratory in Sindney, BC, Canada. Producer defined METHOD Method use for per- and polyfluoroalkyl substances (PFAS) analysis. Producer Defined EPA DRAFT 1633 EPA Draft 1633 method for PFAS. Producer defined SGS AXYS METHOD MLA-110 Rev 02 EPA Draft 1633 method for PFAS. Producer defined SGS AXYS METHOD MLA-111 Rev 03 EPA Draft 1633 method for PFAS after oxidation with hydroxy radicals. Producer defined PWPFAS_TS_PRODUCTIONDATA.csv Comma Separated Value (CSV) file containing data. Data table contains produced water volumes over the first year of production from sampled wells. Producer Defined WELL_ID Description of time series well or alternate sampling location. Producer Defined NWTS-1 Well associated with time series samples. Total vertical depth is approximately 6,300' and the lateral length is approximately 4,900'. Well was fractured using a slickwater hydraulic fracturing fluid. Producer defined NWTS-2 Well associated with time series samples. Total vertical depth is approximately 6,300' and the lateral length is approximately 9,800'. Well was fractured using a crosslinked gel hydraulic fracturing fluid. Producer defined NWTS-3 Well associated with time series samples. Total vertical depth is approximately 6,300' and the lateral length is approximately 9,800'. Well was fractured using a crosslinked gel hydraulic fracturing fluid. Producer defined YEAR Year of production data in YYYY format. Producer Defined 2018 2019 years MONTH Month of production data. Producer Defined OCT October Producer defined NOV November Producer defined DEC December Producer defined JAN January Producer defined FEB February Producer defined MAR March Producer defined APR April Producer defined MAY May Producer defined JUN June Producer defined JUL July Producer defined AUG August Producer defined SEP September Producer defined WATER_BBL Water production in barrels (bbl). Producer Defined 949 13255 bbl U.S. Geological Survey GS ScienceBase mailing address

Denver Federal Center, Building 810, Mail Stop 302

Denver CO 80225 United States 1-888-275-8747 sciencebase@usgs.gov Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Digital Data https://doi.org/10.5066/P13SQVJA None 20250820 Matthew S Varonka U.S. Geological Survey, Northeast Region Research Chemist mailing and physical

National Center, John W Powell FB

Reston VA 20192 703-648-6412 mvaronka@usgs.gov FGDC Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998