Field, laboratory, and third-party quality-control data associated with sites and analytes monitored by the USGS National Water Quality Network, October 2022 through September 2024

From October 2022 through September 2024, the U.S. Geological Survey (USGS) National Water Quality Network (NWQN) monitored 110 surface-water river and stream sites and about 700 groundwater wells for a large number of water-quality analytes, for which associated quality-control data and corresponding statistical summaries are included in this data release. The quality-control data—for samples that were collected in the field (at 109 surface-water sites and 104 groundwater wells), prepared in the laboratory, or prepared by a third party—can be used to assess the quality of environmental data collected by the NWQN through the estimation of bias and variability in reported results. The general analyte groups that were monitored at NWQN surface-water and (or) groundwater sites and have associated quality-control data in this data release include major ions, nutrients, trace elements, pesticides, volatile organic compounds, microbial indicators, sediment, and tritium. For each analyte group, the data tables contain results for one or more of the following types of quality-control samples, where relevant: blanks, matrix spikes, and replicates collected at field sites; laboratory blanks, reagent spikes, and matrix spikes prepared by the USGS National Water Quality Laboratory (NWQL) (quality-control samples prepared by other analyzing laboratories are not included in the current data release); and third-party blanks and reference samples prepared by the USGS Quality Systems Branch (QSB). For each relevant analyte, tables of summary statistics characterize the frequency and concentrations of blank detections, the typical magnitude of and variability in spike and reference-sample recoveries, and the typical variability between replicate concentrations.

Tables included in this data release:

Table1_SiteList_WY23_24.txt: Information about National Water Quality Network sites that have associated quality-control data.

Table2_AnalyteList_WY23_24.txt: Information about National Water Quality Network analytes that have associated quality-control data, including available aquatic-life and (or) human-health benchmarks and selected information regarding analytical methods.

Table3_BlankData_WY23_24.txt: For all relevant analytes, results for blanks collected at field sites, prepared in the laboratory, or prepared by a third party.

Table4_SpikeData_WY23_24.txt: For all relevant analytes, results for matrix spikes prepared in the field and(or) matrix spikes or reagent prepared in the laboratory. For matrix spikes, results of paired environmental samples are included.

Table5_ReplicateData_WY23_24.txt: For all relevant analytes, results for field replicates and paired environmental samples.

Table6_ReferenceData_WY23_24.txt: For all relevant analytes, results for third-party reference samples.

Table7_BlankStats_WY23_24.txt: For all relevant analytes, summary statistics for each type of available blank sample.

Table8_SpikeStats_WY23_24.txt: For all relevant analytes, summary statistics for each type of available spike sample.

Table9_ReplicateStats_WY23_24.txt: For all relevant analytes, summary statistics for field replicates.

Table10_ReferenceStats_WY23_24.txt: For all relevant analytes, summary statistics for reference samples. 

NWQN_QC_DataDictionary_WY23_24.txt: Descriptions of data fields and field values in the data tables.