Analytical recovery is the concentration of an analyte measured in a water-quality sample expressed as a percentage of the known concentration added to the sample (Mueller and others, 2015). Analytical recovery (hereafter referred to as “recovery”) can be used to understand method bias and variability and to assess the temporal changes in a method over time (Martin and others, 2009). This data set includes two tables: one table of field spike recovery data and one table of lab reagent spike recovery data. The table of field spike recovery data includes results from paired environmental and spike samples collected by the National Water Quality Program, National Water-Quality Assessment (NAWQA) Project in surface water and groundwater. These samples were collected as part of the NAWQA Project’s National Water Quality Network: Rivers and Streams assessment, Regional Stream Quality Assessment studies and in multiple groundwater networks following standard practices (Mueller and others, 1997). This table includes environmental and spike water-quality sample data stored in the USGS National Water Information System (NWIS) database (https://dx.doi.org/10.5066/F7P55KJN). Concentrations of pesticides in spike samples, while stored in the NWIS database, are not publically available. The calculation of recovery based on these field sample data is outlined in Mueller and others (2015). Lab reagent spikes are pesticide-free reagent water spiked with a known concentration of pesticide. Lab reagent spikes are prepared in the lab and their recovery can be directly measured. The table of lab reagent spike data contains quality control sample information stored in the USGS National Water Quality Laboratory (NWQL) database. Both tables include fields for data-quality indicators that are described in the data processing steps of this metadata file. These tables were developed in order to support a USGS Scientific Investigations Report with the working title “Considerations for the Preparation of Pesticide Data Analyzed with National Water Quality Laboratory Schedule 2437”. Martin, J.D., Stone, W.W, Wydoski, D.S., and Sandstrom, M.W., 2009, Adjustment of pesticide concentrations for temporal changes in analytical recovery, 1992–2006: U.S. Geological Survey Scientific Investigations Report 2009–5189, 23 p. plus appendixes. Mueller, D.K., Schertz, T.L., Martin, J.D., and Sandstrom, M.W., 2015, Design, analysis, and interpretation of field quality-control data for water-sampling projects: U.S. Geological Survey Techniques and Methods, book 4, chap. C4, 54 p., https://dx.doi.org/10.3133/tm4C4. Mueller, D.K., Martin, J.D. and Lopes, T.J., 1997, Quality-Control Design for Surface-Water Sampling in the National Water-Quality Assessment Program: U.S. Geological Survey Open-File Report 97-223, 8 p. plus appendixes.

This data release contains two tables-one table of field spike recovery data and one table of lab reagent spike recovery data-for pesticides and pesticide degradates analyzed by the USGS National Water Quality Laboratory (NWQL) schedule 2437, and associated metadata. The table of field spike recovery data includes results from paired environmental and spike samples collected by the National Water Quality Program, National Water-Quality Assessment (NAWQA) Project in surface water. The table of lab reagent spike data contains quality-control sample information stored in the NWQL database. Both tables include fields for data-quality indicators that are described in the data processing steps of the metadata file. The tables in this data release contain data for water years 2016-17 and were developed as a follow-up to the analysis for water years 2013-15 conducted by Shoda and others (2017 and 2018). Shoda, M.E., Nowell, L.H., Stone, W.W., Sandstrom, M.W., and Bexfield, L.M., 2018, Data analysis considerations for pesticides determined by National Water Quality Laboratory schedule 2437: U.S. Geological Survey Scientific Investigations Report 2018-5007, 458 p., https://doi.org/10.3133/sir20185007. Shoda, M.E., Nowell, L.H., Bexfield, L.M., Sandstrom, M.W., Stone, W.W., 2017, Recovery data for surface water, groundwater and lab reagent samples analyzed by the USGS National Water Quality Laboratory schedule 2437, water years 2013-15: U.S. Geological Survey data release, https://doi.org/10.5066/F7QZ28G4.

This data release contains two tables-one table of field spike recovery data and one table of lab reagent spike recovery data-for pesticides and pesticide degradates analyzed by the USGS National Water Quality Laboratory (NWQL) schedule 2437, and associated metadata. The table of field spike recovery data includes results from paired environmental and spike samples collected by the National Water Quality Program, National Water-Quality Assessment (NAWQA) Project in surface water. The table of lab reagent spike data contains quality-control sample information stored in the NWQL database. Both tables include fields for data-quality indicators that are described in the data processing steps of the metadata file. The tables in this data release contain data for water years 2016-17 and were developed as a follow-up to the analysis for water years 2013-15 conducted by Shoda and others (2017 and 2018). Shoda, M.E., Nowell, L.H., Stone, W.W., Sandstrom, M.W., and Bexfield, L.M., 2018, Data analysis considerations for pesticides determined by National Water Quality Laboratory schedule 2437: U.S. Geological Survey Scientific Investigations Report 2018-5007, 458 p., https://doi.org/10.3133/sir20185007. Shoda, M.E., Nowell, L.H., Bexfield, L.M., Sandstrom, M.W., Stone, W.W., 2017, Recovery data for surface water, groundwater and lab reagent samples analyzed by the USGS National Water Quality Laboratory schedule 2437, water years 2013-15: U.S. Geological Survey data release, https://doi.org/10.5066/F7QZ28G4.

Replicate water-quality samples are collected and prepared in the field and analyzed in the laboratory in identical ways so that they are considered to be the same in composition and analysis (Mueller and others, 2015). This data set includes one table of duplicate National Water-Quality Assessment Project (NAWQA) surface water and groundwater samples collected between October 1, 2012 and September 30, 2015 and analyzed by the USGS National Water Quality Laboratory (NWQL) using direct aqueous-injection liquid chromatography-tandem mass spectrometry (Schedule 2437; Sandstrom and others, 2015) for the determination of 225 pesticides at 288 sites. Mueller, D.K., Schertz, T.L., Martin, J.D., and Sandstrom, M.W., 2015, Design, analysis, and interpretation of field quality-control data for water-sampling projects: U.S. Geological Survey Techniques and Methods, book 4, chap. C4, 54 p., https://dx.doi.org/10.3133/tm4C4 Sandstrom, M.W., Kanagy, L.K., Anderson, C.A., Kanagy, C.J., 2015, Determination of pesticides and pesticide degradates in filtered water by direct aqueous-injection liquid chromatography-tandem mass spectrometry: U.S. Geological Survey Techniques and Methods, book 5, chap. B11, 54 p., https://dx.doi.org/10.3133/tm5B11

Replicate water-quality samples are collected and prepared in the field and analyzed in the laboratory in identical ways so that they are considered to be the same in composition and analysis (Mueller and others, 2015). This data set includes one table of duplicate National Water-Quality Assessment Project (NAWQA) surface water and groundwater samples collected between October 1, 2012 and September 30, 2015 and analyzed by the USGS National Water Quality Laboratory (NWQL) using direct aqueous-injection liquid chromatography-tandem mass spectrometry (Schedule 2437; Sandstrom and others, 2015) for the determination of 225 pesticides at 288 sites. Mueller, D.K., Schertz, T.L., Martin, J.D., and Sandstrom, M.W., 2015, Design, analysis, and interpretation of field quality-control data for water-sampling projects: U.S. Geological Survey Techniques and Methods, book 4, chap. C4, 54 p., https://dx.doi.org/10.3133/tm4C4 Sandstrom, M.W., Kanagy, L.K., Anderson, C.A., Kanagy, C.J., 2015, Determination of pesticides and pesticide degradates in filtered water by direct aqueous-injection liquid chromatography-tandem mass spectrometry: U.S. Geological Survey Techniques and Methods, book 5, chap. B11, 54 p., https://dx.doi.org/10.3133/tm5B11

This dataset compared the de facto reuse percentage modeled for the 22 surface water sites sampled in Phase II of the drinking water project and the organic chemical data generated as part of the project. This dataset is associated with the following publication: Nguyen , T., P. Westerhoff , E. Furlong, D. Kolpin, A. Batt, H. Mash, K. Schenck, J.S. Boone, J. Rice, and S. Glassmeyer. Modeled De Facto Reuse and Contaminants of Emerging Concern in Drinking Water Source Waters. JOURNAL OF THE AMERICAN WATER WORKS ASSOCIATION. American Water Works Association, Denver, CO, USA, 110(4): E2-E18, (2018).

The National Water-Quality Assessment (NAWQA) Program and National Stream Quality Accounting Network (NASQAN) are U.S. Geological Survey (USGS) monitoring programs that measure pesticide concentrations in the Nation’s streams and rivers, herein collectively referred to as streams. The NAWQA Program began monitoring pesticides in 1992 and the NASQAN Program began monitoring pesticides in 1995. The programs were recently merged to form the USGS National Water Quality Network for Rivers and Streams. Water samples are analyzed for pesticides by the USGS National Water Quality Laboratory (NWQL) using methods developed by the NWQL’s Methods Research and Development team. The NWQL extensively used two analytical methods, gas chromatography/mass spectrometry and liquid chromatography/mass spectrometry, to measure pesticides in filtered water samples during 1992–2012 (old method). In October 2012, the monitoring programs began using direct aqueous-injection liquid chromatography tandem mass spectrometry as a new analytical method for pesticides (new method). The change in analytical methods, however, has the potential to inadvertently introduce bias in analysis of datasets that span the change. The data sets provided in this report were used to document performance of the new method in a variety of stream-water matrices and help quantify potential changes in measurement bias or variability that could be attributed to changes in analytical methods (Martin and others, 2016). Users should consult the report by Martin and others (2016) to understand how these data were collected and used. Measured concentrations and calculated recoveries of 281 pesticides and degradates in paired environmental background water samples and matrix spiked water samples collected at 48 stream-water sites from June 11, 2012 to September 6, 2012 are provided in seven tab-delimited ASCII files with relational database (RDB) format header. A tab-delimited ASCII file (DataDictionaryList.txt) listing DataSet attributes and RDB column formats is also included in this data release. Martin, J.D., Norman, J.E., Sandstrom, M.W., and Rose, C.E., 2016, A field study of selected U.S. Geological Survey analytical methods for measuring pesticides in filtered stream water, June-September 2012: U.S. Geological Survey Scientific Investigations Report, 2017-5049

The National Water-Quality Assessment (NAWQA) Program and National Stream Quality Accounting Network (NASQAN) are U.S. Geological Survey (USGS) monitoring programs that measure pesticide concentrations in the Nation’s streams and rivers, herein collectively referred to as streams. The NAWQA Program began monitoring pesticides in 1992 and the NASQAN Program began monitoring pesticides in 1995. The programs were recently merged to form the USGS National Water Quality Network for Rivers and Streams. Water samples are analyzed for pesticides by the USGS National Water Quality Laboratory (NWQL) using methods developed by the NWQL’s Methods Research and Development team. The NWQL extensively used two analytical methods, gas chromatography/mass spectrometry and liquid chromatography/mass spectrometry, to measure pesticides in filtered water samples during 1992–2012 (old method). In October 2012, the monitoring programs began using direct aqueous-injection liquid chromatography tandem mass spectrometry as a new analytical method for pesticides (new method). The change in analytical methods, however, has the potential to inadvertently introduce bias in analysis of datasets that span the change. The data sets provided in this report were used to document performance of the new method in a variety of stream-water matrices and help quantify potential changes in measurement bias or variability that could be attributed to changes in analytical methods (Martin and others, 2016). Users should consult the report by Martin and others (2016) to understand how these data were collected and used. Measured concentrations and calculated recoveries of 281 pesticides and degradates in paired environmental background water samples and matrix spiked water samples collected at 48 stream-water sites from June 11, 2012 to September 6, 2012 are provided in seven tab-delimited ASCII files with relational database (RDB) format header. A tab-delimited ASCII file (DataDictionaryList.txt) listing DataSet attributes and RDB column formats is also included in this data release. Martin, J.D., Norman, J.E., Sandstrom, M.W., and Rose, C.E., 2016, A field study of selected U.S. Geological Survey analytical methods for measuring pesticides in filtered stream water, June-September 2012: U.S. Geological Survey Scientific Investigations Report, 2017-5049

Data in this release were collected and computed to evaluate the occurrence of pesticides in shallow groundwater in the state of Alabama. Additionally, these data support interpretation in Gill (2023) for a cooperative project between the U.S. Geological Survey and the Alabama Department of Agriculture and Industries. During 2009-2020, samples were collected from twenty-four wells located near agricultural land use in Alabama and evaluated for concentrations of agricultural pesticides and pesticide degradates. Most data produced from the sampling effort are available from the publicly accessible USGS National Water Information System (NWIS; U.S. Geological Survey, 2023). For certain pesticide compounds, data were combined from multiple analytical methods to provide a longer period of record in order to evaluate changes in concentrations and occurrence through time. All groundwater quality data used in Gill (2023), including supporting quality assurance datasets, are included in this data release. References: Gill, A.C., 2023, Pesticide occurrence in shallow groundwater near areas of agricultural land use in Alabama, 2009-2020: U.S. Geological Survey Scientific Investigations Report 2023-xxxx, xx p., https://doi.org/xxxx. U.S. Geological Survey, 2023, National Water Information System data available on the World Wide Web (USGS Water Data for the Nation), accessed April 21, 2023, at http://dx.doi.org/10.5066/F7P55KJN.

Data in this release were collected and computed to evaluate the occurrence of pesticides in shallow groundwater in the state of Alabama. Additionally, these data support interpretation in Gill (2023) for a cooperative project between the U.S. Geological Survey and the Alabama Department of Agriculture and Industries. During 2009-2020, samples were collected from twenty-four wells located near agricultural land use in Alabama and evaluated for concentrations of agricultural pesticides and pesticide degradates. Most data produced from the sampling effort are available from the publicly accessible USGS National Water Information System (NWIS; U.S. Geological Survey, 2023). For certain pesticide compounds, data were combined from multiple analytical methods to provide a longer period of record in order to evaluate changes in concentrations and occurrence through time. All groundwater quality data used in Gill (2023), including supporting quality assurance datasets, are included in this data release. References: Gill, A.C., 2023, Pesticide occurrence in shallow groundwater near areas of agricultural land use in Alabama, 2009-2020: U.S. Geological Survey Scientific Investigations Report 2023-xxxx, xx p., https://doi.org/xxxx. U.S. Geological Survey, 2023, National Water Information System data available on the World Wide Web (USGS Water Data for the Nation), accessed April 21, 2023, at http://dx.doi.org/10.5066/F7P55KJN.