In June and July of 2020, 45 groundwater wells in McHenry County, Illinois, were sampled for water quality (field properties, major ions, nutrients, and trace metals) and 12 wells were sampled for contaminants of emerging concern (pharmaceuticals, pesticides, and wastewater indicator compounds). Quality-assurance and quality-control samples were collected during the June and July 2020 sampling that included equipment blanks, field blanks, and replicates. The results of these samples were used to understand the sources of bias and variability associated with sample collection, processing, storage, and shipping. This data release contains one comma separated values files containing the results of the quality-control sample collection for general water quality (metals, nutrients, and major ions) and contaminants of emerging concern (wastewater indicator compounds and pharmaceuticals). Water-quality data from the associated groundwater monitoring well data are available at the National Water Information System (NWIS) web database (https://doi.org/10.5066/F7P55KJN). Results and discussion of the water quality and contaminants of emerging concern can also be found in the associated scientific investigation report referenced.

The U.S. Geological Survey, in cooperation with the Minnesota Department of Health, conducted a study to determine the occurrence of six unregulated contaminants in source and finished drinking-water samples collected from 67 public water supply systems throughout Minnesota. Minnesota relies on groundwater and surface water sources for drinking water. Land use, such as wastewater discharge and agriculture, is a factor that determines groundwater and surface water quality. The public water supply systems were categorized based on whether the source water is from surface water or groundwater. Groundwater sites were further categorized by expected sources of contamination based on land use: wastewater, agriculture, and mix of wastewater and agriculture. The 67 public water supply systems sampled during this study were composed of 16 surface water (SW), 22 groundwater influenced by wastewater (GWWW), 21 groundwater influenced by agriculture (GWAg), and 8 groundwater influenced by both wastewater and agriculture (GWWW/Ag) facility types. Minnesota finished drinking water from public water supply systems is seldom directly from the source without some degree of treatment. Typically, treatment is to satisfy regulatory requirements or provide aesthetic value rather than designed for the removal of unregulated contaminants. To identify the presence of unregulated contaminants in source and finished drinking water from public water supply facilities, water samples were analyzed for three commonly detected pesticides (atrazine, imidacloprid, and pyrethroids) and three commonly detected pharmaceuticals (caffeine, carbamazepine, and sulfamethoxazole). Concentrations of three target contaminants (atrazine, imidacloprid, and pyrethroids) plus several immunologically similar contaminants and/or three target pharmaceuticals (caffeine, carbamazepine, and sulfamethoxazole) plus several immunologically similar contaminants were determined in source and finished drinking-water samples collected from 22 GWWW, 21 GWAg, 8 GWWW/Ag, and 16 SW public water supply facilities. The target contaminant plus immunologically similar contaminants (as defined by ELISA specifications) are referred to as contaminant groups. Note that each contaminant group may represent a different set of compounds across analyzing laboratories. Samples collected from SW (66 samples) and GWWW/Ag (16 samples) public water supply facilities were analyzed for all six contaminant groups. Samples collected from GWAg (40 samples) facilities were analyzed for the three pesticide groups and samples collected from GWWW (40 samples) facilities were analyzed for the three pharmaceutical groups. A total of 162 water-quality samples were analyzed by three different laboratory entities. All samples were analyzed at the USGS Upper Midwest Water Science Center using the enzyme-linked immunosorbent assay (ELISA) analytical method. All samples were analyzed at the U.S. Geological Survey National Water Quality Laboratory (NWQL) where samples collected for pesticide analysis were analyzed by direct aqueous injection with liquid chromatography and tandem mass spectrometry (LC-MS/MS), except for the target contaminant, atrazine (ATZ1), and samples collected for pharmaceuticals and ATZ1 analysis were analyzed by direct aqueous injection with high performance liquid chromatography and tandem mass spectrometry (HPLC/MS/MS). Samples were also analyzed for select pharmaceuticals at SGS AXYS Services Ltd. (AXYS) by LC-MS/MS. These data are a part of the associated U.S. Geological Survey Scientific Investigations Report 2022-5066 (https://doi.org/10.3133/sir20225066).

The U.S. Geological Survey, in cooperation with the Minnesota Department of Health, conducted a study to determine the occurrence of six unregulated contaminants in source and finished drinking-water samples collected from 67 public water supply systems throughout Minnesota. Minnesota relies on groundwater and surface water sources for drinking water. Land use, such as wastewater discharge and agriculture, is a factor that determines groundwater and surface water quality. The public water supply systems were categorized based on whether the source water is from surface water or groundwater. Groundwater sites were further categorized by expected sources of contamination based on land use: wastewater, agriculture, and mix of wastewater and agriculture. The 67 public water supply systems sampled during this study were composed of 16 surface water (SW), 22 groundwater influenced by wastewater (GWWW), 21 groundwater influenced by agriculture (GWAg), and 8 groundwater influenced by both wastewater and agriculture (GWWW/Ag) facility types. Minnesota finished drinking water from public water supply systems is seldom directly from the source without some degree of treatment. Typically, treatment is to satisfy regulatory requirements or provide aesthetic value rather than designed for the removal of unregulated contaminants. To identify the presence of unregulated contaminants in source and finished drinking water from public water supply facilities, water samples were analyzed for three commonly detected pesticides (atrazine, imidacloprid, and pyrethroids) and three commonly detected pharmaceuticals (caffeine, carbamazepine, and sulfamethoxazole). Concentrations of three target contaminants (atrazine, imidacloprid, and pyrethroids) plus several immunologically similar contaminants and/or three target pharmaceuticals (caffeine, carbamazepine, and sulfamethoxazole) plus several immunologically similar contaminants were determined in source and finished drinking-water samples collected from 22 GWWW, 21 GWAg, 8 GWWW/Ag, and 16 SW public water supply facilities. The target contaminant plus immunologically similar contaminants (as defined by ELISA specifications) are referred to as contaminant groups. Note that each contaminant group may represent a different set of compounds across analyzing laboratories. Samples collected from SW (66 samples) and GWWW/Ag (16 samples) public water supply facilities were analyzed for all six contaminant groups. Samples collected from GWAg (40 samples) facilities were analyzed for the three pesticide groups and samples collected from GWWW (40 samples) facilities were analyzed for the three pharmaceutical groups. A total of 162 water-quality samples were analyzed by three different laboratory entities. All samples were analyzed at the USGS Upper Midwest Water Science Center using the enzyme-linked immunosorbent assay (ELISA) analytical method. All samples were analyzed at the U.S. Geological Survey National Water Quality Laboratory (NWQL) where samples collected for pesticide analysis were analyzed by direct aqueous injection with liquid chromatography and tandem mass spectrometry (LC-MS/MS), except for the target contaminant, atrazine (ATZ1), and samples collected for pharmaceuticals and ATZ1 analysis were analyzed by direct aqueous injection with high performance liquid chromatography and tandem mass spectrometry (HPLC/MS/MS). Samples were also analyzed for select pharmaceuticals at SGS AXYS Services Ltd. (AXYS) by LC-MS/MS. These data are a part of the associated U.S. Geological Survey Scientific Investigations Report 2022-5066 (https://doi.org/10.3133/sir20225066).

The U.S. Geological Survey, in cooperation with the Minnesota Department of Health, conducted a study to determine the occurrence of unregulated contaminants in source and finished drinking waters throughout Minnesota. Minnesota relies on both groundwater and surface water sources for drinking water, which may be vulnerable to influences such as wastewater discharge and/or agricultural activities. Thus, drinking water facilities apply some form of treatment to source waters prior to distribution. Although drinking water treatment is mostly focused on satisfying regulatory requirements, it may provide secondary benefits for removal of unregulated contaminants. In 2019, 2021, and 2022, paired source and finished drinking water was collected from 100 facilities and characterized for select organic contaminants. Samples were analyzed for some combination of alkylphenols, benzotriazoles/benzothiazoles, hormones, illicit drugs, personal care products, pesticides, per- and polyfluoroalkyl substances, pharmaceuticals, plasticizers, and wastewater indicators, depending on potential influences from the watershed.

The U.S. Geological Survey, in cooperation with the Minnesota Department of Health, conducted a study to determine the occurrence of unregulated contaminants in source and finished drinking waters throughout Minnesota. Minnesota relies on both groundwater and surface water sources for drinking water, which may be vulnerable to influences such as wastewater discharge and/or agricultural activities. Thus, drinking water facilities apply some form of treatment to source waters prior to distribution. Although drinking water treatment is mostly focused on satisfying regulatory requirements, it may provide secondary benefits for removal of unregulated contaminants. In 2019, 2021, and 2022, paired source and finished drinking water was collected from 100 facilities and characterized for select organic contaminants. Samples were analyzed for some combination of alkylphenols, benzotriazoles/benzothiazoles, hormones, illicit drugs, personal care products, pesticides, per- and polyfluoroalkyl substances, pharmaceuticals, plasticizers, and wastewater indicators, depending on potential influences from the watershed.

These data files include georeferenced water-quality data with associated time stamps (Central Standard Time) for basic water-quality parameters as measured by a towed multiparameter sonde (YSI 6920 sonde) from a manned boat in the Chicago Sanitary and Ship Canal. Data were collected on February 25-27, 2010, and again on March 2-3, 2010. The data collected in February 2010 had the sonde on a fixed mount about 1 foot below the surface. The data collected in March 2010 had the sonde on a towed cable about 7-9 feet below the surface. All data have been edited and reviewed. Omitted data have been flagged with a data value of -9999 in the data files.

These data files include georeferenced water-quality data with associated time stamps (Central Standard Time) for basic water-quality parameters as measured by a towed multiparameter sonde (YSI 6920 sonde) from a manned boat in the Chicago Sanitary and Ship Canal. Data were collected on February 25-27, 2010, and again on March 2-3, 2010. The data collected in February 2010 had the sonde on a fixed mount about 1 foot below the surface. The data collected in March 2010 had the sonde on a towed cable about 7-9 feet below the surface. All data have been edited and reviewed. Omitted data have been flagged with a data value of -9999 in the data files.

The U.S. Geological Survey, in cooperation with the Minnesota Department of Health, conducted a study to determine the occurrence of unregulated contaminants in source and finished drinking waters throughout Minnesota. Minnesota relies on both groundwater and surface water sources for drinking water, which may be vulnerable to influences such as wastewater discharge and/or agricultural activities. Thus, drinking water facilities apply some form of treatment to source waters prior to distribution. Although drinking water treatment is mostly focused on satisfying regulatory requirements, it may provide secondary benefits for removal of unregulated contaminants. In 2019, 2021, and 2022, paired source and finished drinking water was collected from 100 facilities and characterized for select organic contaminants. Samples were analyzed for some combination of alkylphenols, benzotriazoles/benzothiazoles, hormones, illicit drugs, personal care products, pesticides, per- and polyfluoroalkyl substances, pharmaceuticals, plasticizers, and wastewater indicators, depending on potential influences from the watershed.

The U.S. Geological Survey, in cooperation with the Minnesota Department of Health, conducted a study to determine the occurrence of unregulated contaminants in source and finished drinking waters throughout Minnesota. Minnesota relies on both groundwater and surface water sources for drinking water, which may be vulnerable to influences such as wastewater discharge and/or agricultural activities. Thus, drinking water facilities apply some form of treatment to source waters prior to distribution. Although drinking water treatment is mostly focused on satisfying regulatory requirements, it may provide secondary benefits for removal of unregulated contaminants. In 2019, 2021, and 2022, paired source and finished drinking water was collected from 100 facilities and characterized for select organic contaminants. Samples were analyzed for some combination of alkylphenols, benzotriazoles/benzothiazoles, hormones, illicit drugs, personal care products, pesticides, per- and polyfluoroalkyl substances, pharmaceuticals, plasticizers, and wastewater indicators, depending on potential influences from the watershed.

Groundwater samples were collected and analyzed from 782 wells as part of the National Water-Quality Assessment Project of the U.S. Geological Survey National Water-Quality Program and the water-quality data and quality-control data are included in this data release. The samples were collected from three types of well networks: principal aquifer study networks, which are used to assess the quality of groundwater used for public water supply; land-use study networks, which are used to assess land-use effects on shallow groundwater quality, and major aquifer study networks, which are used to assess the quality of groundwater used for domestic supply. Groundwater samples were analyzed for a large number of water-quality indicators and constituents, including nutrients, major ions, trace elements, volatile organic compounds (VOCs), pesticides, radionuclides, and microbial indicators. Data from samples collected between 2012 and 2019 are associated with networks described in a collection of data series reports and associated data releases (Arnold and others, 2016a,b, 2017a,b, 2018a,b, 2020a,b; Kingsbury and others, 2020 and 2021). This data release includes data from networks sampled in 2019 through 2022. For some networks, certain constituent group data were not completely reviewed and released by the analyzing laboratory for all network sites in time for publication of this data release. For networks with incomplete data, no data were published for the incomplete constituent group(s). Datasets excluded from this data release because of incomplete results will be included in the earliest data release published after the dataset is complete. NOTE: While previous versions are available from the author, all the records in previous versions can be found in version 3.0. First posted - December 12, 2021 (available from author) Revised - January 27, 2023 (version 2.0: available from author) Revised - November 2, 2023 (version 3.0) The compressed file (NWQP_GW_QW_DataRelease_v3.zip) contains 24 files: 23 files of groundwater-quality, quality-control data, and general information in ASCII text tab-delimited format, and one corresponding metadata file in xml format that includes descriptions of all the tables and attributes. A shapefile containing study areas for each of the sampled groundwater networks also is provided as part of this data release and is described in the metadata (Network_Boundaries_v3.zip). The files are as follows: Description_of_Data_Field_v3.txt: Information for all constituents and ancillary information found in Tables 3 through 21. Network_Reference_List_v3.txt: References used for the description of the networks sampled by the USGS NAWQA Project. Table_1_site_list_v3.txt: Information about wells that have environmental data. Table_2_parameters_v3.txt: Constituent primary uses and sources; laboratory analytical schedules and sampling period; USGS parameter codes (pcodes); comparison thresholds; and reporting levels. Table_3_qw_indicators_v3.txt: Water-quality indicators in groundwater samples collected by the USGS NAWQA Project. Table_4_nutrients_v3.txt: Nutrients and dissolved organic carbon in groundwater samples collected by the USGS NAWQA Project. Table_5_major_ions_v3.txt: Major and minor ions in groundwater samples collected by the USGS NAWQA Project. Table_6_trace_elements_v3.txt: Trace elements in groundwater samples collected by the USGS NAWQA Project. Table_7_vocs_v3.txt: Volatile organic compounds (VOCs) in groundwater samples collected by the USGS NAWQA Project. Table_8_pesticides_v3.txt: Pesticides in groundwater samples collected by the USGS NAWQA Project. Table_9_radchem_v3.txt: Radionuclides in groundwater samples collected by the USGS NAWQA Project. Table_10_micro_v3.txt: Microbiological indicators in groundwater samples collected by the USGS NAWQA Project. Table_11_qw_ind_QC_v3.txt: Water-quality indicators in groundwater replicate samples collected by the USGS NAWQA Project.