Data from Decadal Change in Groundwater Quality Web Site, 1988-2022

Dates

Publication Date: 2023-09-13
Start Date: 1988-01-01
End Date: 2022-12-31

Citation

Lindsey, B.D., Dondero, A.M., Watson, E., and Johnson, T.D., 2023, Data from Decadal Change in Groundwater Quality Web Site, 1988-2022: U.S. Geological Survey data release, https://doi.org/10.5066/P9YEB7FS.

Summary

Evaluating Decadal Changes in Groundwater Quality: Groundwater-quality data were collected from 5,000 wells between 1988-2001 (first decadal sampling event) by the National Water-Quality Assessment Project. Samples are collected in groups of 20-30 wells with similar characteristics called networks. About 1,500 of these wells in 67 networks were sampled again approximately 10 years later between 2002-2012 (second sampling event) to evaluate decadal changes in groundwater quality. Between 2012 and 2022 (third sampling event), a subset of these networks were sampled again, allowing additional results to be displayed on the web page: Decadal changes in groundwater quality (https://nawqatrends.wim.usgs.gov/decadal/). This is the seventh [...]

Summary

Evaluating Decadal Changes in Groundwater Quality: Groundwater-quality data were collected from 5,000 wells between 1988-2001 (first decadal sampling event) by the National Water-Quality Assessment Project. Samples are collected in groups of 20-30 wells with similar characteristics called networks. About 1,500 of these wells in 67 networks were sampled again approximately 10 years later between 2002-2012 (second sampling event) to evaluate decadal changes in groundwater quality. Between 2012 and 2022 (third sampling event), a subset of these networks were sampled again, allowing additional results to be displayed on the web page: Decadal changes in groundwater quality (https://nawqatrends.wim.usgs.gov/decadal/). This is the seventh iteration of data added to the website. With the additional data, it is possible to evaluate changes in water quality between the 2nd and 3rd sampling events for 76 networks, changes in water quality between the 1st and 3rd sampling events for 63 networks, and changes across all 3 sampling events for 60 networks. Samples were obtained from monitoring wells, domestic-supply wells, and some public-supply wells before any treatment on the system.

Groundwater samples used to evaluate decadal change were collected from networks of wells with similar characteristics. Some networks, consisting of domestic or public-supply wells, were used to assess changes in the quality of groundwater used for drinking water supply. Other networks, consisting of monitoring wells, assessed changes in the quality of shallow groundwater underlying key land-use types such as agricultural or urban lands. Networks were chosen based on geographic distribution across the Nation and to represent the most important water-supply aquifers and specific land-use types.

Decadal changes in concentrations of nutrients, metals, and pesticides and other organic contaminants in groundwater were evaluated in a total of 89 networks across the Nation by comparing changes between selected sampling events.

Decadal changes in median concentrations for a network are classified as large, small, or no change in comparison to a benchmark concentration. For example, a large change in chloride concentrations indicates that the probability of the test is less than or equal to 0.10 and the median of all differences in concentrations in a network is greater than 5 percent of the chloride benchmark per decade. For chloride, which has a Secondary Maximum Contaminant level of 250 milligrams per liter, this would mean the change in concentration exceeded 12.5 milligrams per liter (mg/L), or 5 percent of the benchmark.

230 networks were sampled from 1988 to 2001 to assess the status of the Nation's groundwater quality. Each dot on the map on the "About-Learn more" tab of the Decadal mapper website, (https://nawqatrends.wim.usgs.gov/decadal/) represents the center point (centroid) of a network of about 20 to 30 wells. Networks sampled in the first sampling event only are shown in green. There were 67 networks resampled from 2002 to 2012 to assess decadal changes in groundwater quality. Networks sampled from 2012 to 2022 and at least one previous sampling event are shown in orange and trend networks that have not yet been resampled in the third decadal sampling event are shown in blue. Networks sampled in the first and second sampling events but are no longer being sampled are shown in gray.

Contacts

Point of Contact :: Bruce D Lindsey
Originator :: Bruce D Lindsey, Amanda M. Dondero, Elise Watson, Tyler D Johnson
Metadata Contact :: Jennifer B Sharpe
Publisher :: U.S. Geological Survey
Distributor :: U.S. Geological Survey - ScienceBase
SDC Data Owner :: Earth System Processes Division
USGS Mission Area :: Water Resources

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Decadal_Change_V7_Metadata.xml Original FGDC Metadata	View	105.89 KB	application/fgdc+xml
Inorganic_Statistics_Table_CY12_V7.csv		13.16 KB	text/csv
Inorganic_Statistics_Table_CY13_V7.csv		15.14 KB	text/csv
Inorganic_Statistics_Table_CY23_V7.csv		17.31 KB	text/csv
Inorganic_Statistics_Table_CY123_V7.csv		14.55 KB	text/csv
Organic_Statistics_Table_CY13_V7.csv		407 Bytes	text/csv
Organic_Statistics_Table_CY23_V7.csv		482 Bytes	text/csv
Water_Quality_Data_V7.csv		4.42 MB	text/csv
Water_Quality_Data_VOCs_V7.csv		44.7 KB	text/csv
Decadal_Change_Network_Centroids_V7.csv		9.03 KB	text/csv
Decadal_Change_Network_Wells_V7.csv		97.53 KB	text/csv
Decadal_Data_Dictionary_V7.csv		5.37 KB	text/csv

Related External Resources

Type: Related Primary Publication

Lindsey, B.D., Dondero, A.M., Watson, E., and Johnson, T.D., 2023, Decadal Change in Groundwater Quality: U.S. Geological Survey Web Pages, https://nawqatrends.wim.usgs.gov/Decadal/	https://nawqatrends.wim.usgs.gov/Decadal/

Purpose

The purpose of this study is to determine if the quality of the Nation's groundwater has become better, worse, or stayed the same during 1988-2022. Evaluating changes in groundwater quality at the decadal scale is one component of a larger effort to understand the quality of the Nation's water resources and how water quality conditions are changing with time.

Data from Decadal Change in Groundwater Quality Web Site, 1988-2022

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