This U.S. Geological Survey data release provides a comprehensive dataset of water-quality data and sampling-site characteristics collected in 1978–2018 during a study of the effects of land disposal of treated wastewater on groundwater quality in an unconsolidated sand and gravel aquifer on Cape Cod, Massachusetts. Treated sewage-derived wastewater was discharged to rapid-infiltration beds at Joint Base Cape Cod for nearly 60 years before the disposal was moved to a different location in December 1995. The discharge formed a plume of contaminated groundwater that partly discharges to a glacial kettle lake about 1,600 feet from the beds and extends about 4.5 miles toward coastal saltwater bodies at Vineyard Sound. Water-quality samples were collected from monitoring wells, multilevel samplers (MLSs), continuous multichannel tubing samplers (CMTs), AMS gas-vapor sampling points (AMS, Inc., American Falls, Idaho), piezometers, temporary borings drilled by direct-push methods, and surface-water bodies to characterize the nature and extent of the contaminated groundwater and to observe the water-quality changes before and after wastewater disposal ended in 1995. Data are presented here for 604 wells (at 188 well-cluster locations), 1,155 MLS ports (at 61 locations), 42 CMT ports (at 6 locations), 13 gas-vapor points (at 1 location), 17 piezometers (at 5 locations), 536 depth intervals in direct-push profile borings (at 68 locations), 1 glacial kettle lake, and 1 wastewater-disposal discharge in and near the treated-wastewater plume. About 20,740 visits were made to individual sampling points between 1978 to 2018. This data release presents field water-quality measurements (specific conductance, pH, dissolved oxygen, turbidity and temperature; iron, MBAS and phosphate concentrations; and alkalinity); absorbance of ultraviolet/visible light; and concentrations of selected gases (including nitrous oxide, methane, dissolved inorganic carbon), dissolved organic carbon, selected nitrogen species (including nitrate, nitrite, ammonium, and total dissolved nitrogen), and selected inorganic solutes (including cations, anions, and minor elements). Information on sample collection and processing can be found in the Federal Geographic Data Committee (FGDC) metadata and “TableDefs CapeCodToxicsDatabase.xlsx.” The data are presented in two formats: Microsoft (MS) Access database (.accdb) and comma-delimited text (.csv) files. The MS Access version of the database (”DataRelease_CapeCodToxicsDatabase_v1.1.accdb”) contains 15 data tables linked by established relationships and 4 queries that repackage the data for the convenience of the user. Versions of the 4 queries and 15 tables exported from the MS Access database as comma-delimited text files have been zipped together by type (”tables” and ”queries,“ respectively). The text files are comma delimited, contain headings, and use double quotation marks to denote text fields. Numeric fields enclosed in double quotation marks are treated as text to preserve number formatting. Users not familiar with MS Access may prefer the text files to the MS Access database. The database can be reconstructed in Access or another relational data management platform from text-file tables in conjunction with the physical data model, the definitions of the table and field descriptions, and the Structured Query Language (SQL) commands described in a readme file zipped with the query text files. The table descriptions, field definitions, and significant figures for this database are documented by “TableDefs CapeCodToxicsDatabase.xlsx” and the FGDC metadata. The physical data model for this database is documented by “Relationships for CapeCodToxicsDatabase.jpg.” The relationships expressed in the .jpg file are further explained by an MS Word document titled “Relationships for CapeCodToxicsDatabase.docx.” Three types of data are included in the data tables: site and sample characteristics, water-quality data, and

This U.S. Geological Survey data release provides a comprehensive dataset of water-quality data and sampling-site characteristics collected in 1978–2018 during a study of the effects of land disposal of treated wastewater on groundwater quality in an unconsolidated sand and gravel aquifer on Cape Cod, Massachusetts. Treated sewage-derived wastewater was discharged to rapid-infiltration beds at Joint Base Cape Cod for nearly 60 years before the disposal was moved to a different location in December 1995. The discharge formed a plume of contaminated groundwater that partly discharges to a glacial kettle lake about 1,600 feet from the beds and extends about 4.5 miles toward coastal saltwater bodies at Vineyard Sound. Water-quality samples were collected from monitoring wells, multilevel samplers (MLSs), continuous multichannel tubing samplers (CMTs), AMS gas-vapor sampling points (AMS, Inc., American Falls, Idaho), piezometers, temporary borings drilled by direct-push methods, and surface-water bodies to characterize the nature and extent of the contaminated groundwater and to observe the water-quality changes before and after wastewater disposal ended in 1995. Data are presented here for 604 wells (at 188 well-cluster locations), 1,155 MLS ports (at 61 locations), 42 CMT ports (at 6 locations), 13 gas-vapor points (at 1 location), 17 piezometers (at 5 locations), 536 depth intervals in direct-push profile borings (at 68 locations), 1 glacial kettle lake, and 1 wastewater-disposal discharge in and near the treated-wastewater plume. About 20,740 visits were made to individual sampling points between 1978 to 2018. This data release presents field water-quality measurements (specific conductance, pH, dissolved oxygen, turbidity and temperature; iron, MBAS and phosphate concentrations; and alkalinity); absorbance of ultraviolet/visible light; and concentrations of selected gases (including nitrous oxide, methane, dissolved inorganic carbon), dissolved organic carbon, selected nitrogen species (including nitrate, nitrite, ammonium, and total dissolved nitrogen), and selected inorganic solutes (including cations, anions, and minor elements). Information on sample collection and processing can be found in the Federal Geographic Data Committee (FGDC) metadata and “TableDefs CapeCodToxicsDatabase.xlsx.” The data are presented in two formats: Microsoft (MS) Access database (.accdb) and comma-delimited text (.csv) files. The MS Access version of the database (”DataRelease_CapeCodToxicsDatabase.accdb”) contains 15 data tables linked by established relationships and 4 queries that repackage the data for the convenience of the user. Versions of the 4 queries and 15 tables exported from the MS Access database as comma-delimited text files have been zipped together by type (”tables” and ”queries,“ respectively). The text files are comma delimited, contain headings, and use double quotation marks to denote text fields. Numeric fields enclosed in double quotation marks are treated as text to preserve number formatting. Users not familiar with MS Access may prefer the text files to the MS Access database. The database can be reconstructed in Access or another relational data management platform from text-file tables in conjunction with the physical data model, the definitions of the table and field descriptions, and the Structured Query Language (SQL) commands described in a readme file zipped with the query text files. The table descriptions, field definitions, and significant figures for this database are documented by “TableDefs CapeCodToxicsDatabase.xlsx” and the FGDC metadata. The physical data model for this database is documented by “Relationships for CapeCodToxicsDatabase.jpg.” The relationships expressed in the .jpg file are further explained by an MS Word document titled “Relationships for CapeCodToxicsDatabase.docx.” Three types of data are included in the data tables: site and sample characteristics, water-quality data, and

This U.S. Geological Survey (USGS) data release provides a comprehensive dataset of water-quality results, physical-parameter measurements, hydrologic measurements, and site information collected to study the nature and extent of water quality along groundwater flow paths adjacent to glacial-kettle lakes on Cape Cod, Massachusetts. Water-quality samples were collected in 2003, 2005, and 2012 through 2018 in and near seven kettle lakes located on western Cape Cod, with most of the data collected in 2015-2017 from Ashumet Pond, which is located in the towns of Falmouth and Mashpee. Data were also collected at other lakes to compare the lake-specific influences of geochemistry and hydrology on the downgradient groundwater systems. Samples were collected over the course of multi-day and multi-month sampling events to capture the influence of annual and diel changes in the lakes. Water-quality results are presented for groundwater samples collected from monitoring wells and multilevel samplers (MLS) located downgradient from the lakes; shallow groundwater samples from beneath the lake bottoms (also referred to herein as porewater samples) collected near shore by using microwells, also known as pushpoints (manufactured by M.H.E. Products1), installed 5-100 centimeters below the lake-bottom surface into known groundwater upwelling and lake-water downwelling zones near the lake shore; grab samples of lake water collected in conjunction with the near-shore groundwater samples; and profiles of the lake water column collected in deeper parts of the lake basins. The data include field water-quality measurements of specific conductance, pH, dissolved oxygen, temperature, and alkalinity (incremental field titration method) using single-parameter field probes as well as multiprobe sondes; concentrations of samples collected for selected organic and inorganic solutes, including major cations and anions, minor elements, nitrate, nitrite, ammonium, total dissolved nitrogen, dissolved organic carbon, and dissolved inorganic carbon; concentrations of dissolved gases, including nitrous oxide and methane, absorbance of ultraviolet/visible light; stable isotopic ratios of carbon (delta 13C, d13C) measured in dissolved inorganic carbon; isotope ratios of oxygen (d18O) and hydrogen (d2H) measured in water; isotope ratios of oxygen (d18O) and nitrogen (d15N) measured in nitrate plus nitrite; and isotope ratios of oxygen (d18O) measured in dissolved oxygen gas. The data release also includes results from analyses of sediment-core material collected from the sediment surface to 30 centimeters below the lake bottom, and analyses of aquatic vegetation and biofilms on pebble surfaces in Ashumet Pond. The sediment-core results include total carbon and nitrogen content of dried organic material scraped from the pebbles, d13C and d15N of carbon and nitrogen of the organic matter, extractions of ammonium, and carbon dioxide and oxygen measurements used to estimate potential respiration rates from incubation experiments. The data are compiled into ten Excel (.xlsx) tables: (1) A summary of all the sampling event names and dates (Summary Sampling Events.xlsx), (2) sample information, field measurements, and results from laboratory water-quality analyses for environmental samples collected from monitoring wells, MLSs, lake-basin profiles, and near-shore pushpoints (Water Quality Samples.xlsx), (3) results from selected water-quality analytes for laboratory duplicates, laboratory blanks, and equipment rinseate samples (QAQC Samples.xlsx), (4) distance from shore and lake-stage measurements for Ashumet Pond pushpoint site ASHPD-GWOUT-R-N at select times used in a regression equation to estimate distance to shore, and measured distances between pushpoint, MLS, and well locations relative to site ASHPD-GWOUT-R-N (Distance Calculations.xlsx), (5) approximate water-level altitudes at monitoring well and MLS sites calculated from water-level measurements made at

This U.S. Geological Survey (USGS) data release provides a comprehensive dataset of water-quality results, physical-parameter measurements, hydrologic measurements, and site information collected to study the nature and extent of water quality along groundwater flow paths adjacent to glacial-kettle lakes on Cape Cod, Massachusetts. Water-quality samples were collected in 2003, 2005, and 2012 through 2018 in and near seven kettle lakes located on western Cape Cod, with most of the data collected in 2015-2017 from Ashumet Pond, which is located in the towns of Falmouth and Mashpee. Data were also collected at other lakes to compare the lake-specific influences of geochemistry and hydrology on the downgradient groundwater systems. Samples were collected over the course of multi-day and multi-month sampling events to capture the influence of annual and diel changes in the lakes. Water-quality results are presented for groundwater samples collected from monitoring wells and multilevel samplers (MLS) located downgradient from the lakes; shallow groundwater samples from beneath the lake bottoms (also referred to herein as porewater samples) collected near shore by using microwells, also known as pushpoints (manufactured by M.H.E. Products1), installed 5-100 centimeters below the lake-bottom surface into known groundwater upwelling and lake-water downwelling zones near the lake shore; grab samples of lake water collected in conjunction with the near-shore groundwater samples; and profiles of the lake water column collected in deeper parts of the lake basins. The data include field water-quality measurements of specific conductance, pH, dissolved oxygen, temperature, and alkalinity (incremental field titration method) using single-parameter field probes as well as multiprobe sondes; concentrations of samples collected for selected organic and inorganic solutes, including major cations and anions, minor elements, nitrate, nitrite, ammonium, total dissolved nitrogen, dissolved organic carbon, and dissolved inorganic carbon; concentrations of dissolved gases, including nitrous oxide and methane, absorbance of ultraviolet/visible light; stable isotopic ratios of carbon (delta 13C, d13C) measured in dissolved inorganic carbon; isotope ratios of oxygen (d18O) and hydrogen (d2H) measured in water; isotope ratios of oxygen (d18O) and nitrogen (d15N) measured in nitrate plus nitrite; and isotope ratios of oxygen (d18O) measured in dissolved oxygen gas. The data release also includes results from analyses of sediment-core material collected from the sediment surface to 30 centimeters below the lake bottom, and analyses of aquatic vegetation and biofilms on pebble surfaces in Ashumet Pond. The sediment-core results include total carbon and nitrogen content of dried organic material scraped from the pebbles, d13C and d15N of carbon and nitrogen of the organic matter, extractions of ammonium, and carbon dioxide and oxygen measurements used to estimate potential respiration rates from incubation experiments. The data are compiled into ten Excel (.xlsx) tables: (1) A summary of all the sampling event names and dates (Summary Sampling Events.xlsx), (2) sample information, field measurements, and results from laboratory water-quality analyses for environmental samples collected from monitoring wells, MLSs, lake-basin profiles, and near-shore pushpoints (Water Quality Samples.xlsx), (3) results from selected water-quality analytes for laboratory duplicates, laboratory blanks, and equipment rinseate samples (QAQC Samples.xlsx), (4) distance from shore and lake-stage measurements for Ashumet Pond pushpoint site ASHPD-GWOUT-R-N at select times used in a regression equation to estimate distance to shore, and measured distances between pushpoint, MLS, and well locations relative to site ASHPD-GWOUT-R-N (Distance Calculations.xlsx), (5) approximate water-level altitudes at monitoring well and MLS sites calculated from water-level measurements made at

This data release provides analytical and other data in support of an analysis of nitrogen transport and transformation in groundwater and in a subterranean estuary in the Eel River and onshore locations on the Seacoast Shores peninsula, Falmouth, Massachusetts. The analysis is described in U.S. Geological Survey Scientific Investigations Report 2018-5095 by Colman and others (2018). This data release is structured as a set of comma-separated values (CSV) files, each of which contains data columns for laboratory (if applicable), USGS Site Name, date sampled, time sampled, and columns of specific analytical and(or) other data. The .csv data files have the same number of rows and each row in each .csv file corresponds to the same sample. Blank cells in a .csv file indicate that the sample was not analyzed for that constituent. The data release also provides a Data Dictionary (Data_Dictionary.csv) that provides the following information for each constituent (analyte): laboratory or data source, data type, description of units, method, minimum reporting limit, limit of quantitation if appropriate, method reference citations, minimum, maximum, median, and average values for each analyte. The data release also contains a file called Abbreviations in Data_Dictionary.pdf that contains all of the abbreviations in the Data Dictionary and in the well characteristics file in the companion report, Colman and others (2018).

This data release provides analytical and other data in support of an analysis of nitrogen transport and transformation in groundwater and in a subterranean estuary in the Eel River and onshore locations on the Seacoast Shores peninsula, Falmouth, Massachusetts. The analysis is described in U.S. Geological Survey Scientific Investigations Report 2018-5095 by Colman and others (2018). This data release is structured as a set of comma-separated values (CSV) files, each of which contains data columns for laboratory (if applicable), USGS Site Name, date sampled, time sampled, and columns of specific analytical and(or) other data. The .csv data files have the same number of rows and each row in each .csv file corresponds to the same sample. Blank cells in a .csv file indicate that the sample was not analyzed for that constituent. The data release also provides a Data Dictionary (Data_Dictionary.csv) that provides the following information for each constituent (analyte): laboratory or data source, data type, description of units, method, minimum reporting limit, limit of quantitation if appropriate, method reference citations, minimum, maximum, median, and average values for each analyte. The data release also contains a file called Abbreviations in Data_Dictionary.pdf that contains all of the abbreviations in the Data Dictionary and in the well characteristics file in the companion report, Colman and others (2018).

This data release presents water-quality and streamflow data from 12 streams on Cape Cod, Massachusetts, which were used to identify potential land areas that are sources of high nitrogen loading from groundwater directly to streams. The sources of nitrogen loading to groundwater in this region include wastewater from septic systems and fertilizer and stormwater runoff. Streamflow in the area is highly influenced by groundwater and not by direct outflows of treated wastewater. This dataset contains stream site information (CapeCodStreams_SiteInfo.csv), field and laboratory observations (CapeCodStreams_Field_Lab_QW.csv), and information on streamflow and calculated nitrogen loads (CapeCodStreams_Flow_and_Loads.csv). Additionally, the dataset provides information on simulated groundwater recharge areas contributing to individual stream reaches. Recharge area characteristics, including size, recharge quantity, groundwater travel time, nitrogen-yield characteristics, and land-use classifications, are provided (CapeCodStreams_RA_Char.csv and CapeCodStreams_RA_Wshed_Load.csv). A data dictionary (CapeCodStreams_Data_Dictionary.csv) is provided to describe column attributes and define attribute units.

Groundwater, surface-water, and associated quality assurance samples were collected downgradient of an abandoned fire training area and wastewater infiltration beds on western Cape Cod, Massachusetts and analyzed for per- and polyfluoroalkyl substances (PFAS) from 2014-2019. Water-quality properties measured at the time of sample collection include pH, specific conductance, temperature, and dissolved oxygen. Samples were also analyzed for other chemical constituents including major and selected minor inorganic constituents, nutrients, and UV absorbance. Although selected results have been previously published in several data releases, this data release includes the entire suite of field and chemical constituents. PFAS data tables are derived from multiple data sources: Barber and others, 2017; Ruyle and others, 2021; and Tokranov and others, 2021. Other field and chemical data were derived from those sources as well as from Hull and others, 2021 and Repert and others, 2023. PFAS data from different sources were converted to a uniform format. See related external resources for listed citations.

Groundwater, surface water, and associated quality assurance samples were collected downgradient of an abandoned fire training area and wastewater infiltration beds on western Cape Cod, Massachusetts and analyzed for per- and polyfluoroalkyl substances (PFAS) from 2014-2019. Water-quality properties measured at the time of sample collection include pH, specific conductance, temperature, and dissolved oxygen. Samples were also analyzed for other chemical constituents including major and selected minor inorganic constituents, nutrients, and UV absorbance. Although selected results have been previously published in several data releases, this data release includes the entire suite of field and chemical constituents. PFAS concentration data tables were derived from multiple data sources: Barber and others, 2017; Ruyle and others, 2021; and Tokranov and others, 2021a and 2021b. Other field and chemical data were derived from those sources as well as from Hull and others, 2021 and Repert and others, 2023. PFAS data from different sources were converted to a uniform format. See Related External Resources for listed citations.

Groundwater, surface-water, and associated quality assurance samples were collected across western Cape Cod, Massachusetts and analyzed for per- and polyfluoroalkyl substances (PFAS) from September 2019 through November 2024. Water-quality properties measured at the time of sample collection included pH, specific conductance, temperature, and dissolved oxygen. Samples were also analyzed for other chemical constituents including major and selected minor inorganic constituents, nutrients, and pharmaceuticals. This data release contains three files, data dictionary and two datasets in tabular format: 1) DataDictionary_CapeCodPFAS_2019_2024.csv -- Definitions for parameters in each table. 2) CapeCodPFAS_2019_2024.csv -- Location information, field properties, and laboratory results for inorganic constituents, nutrients, and PFAS. 3) CapeCod_Pharmaceuticals_June2022.csv -- Site information and pharmaceutical results for a subset of samples collected at the Quashnet River in June 2022.