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Water quality and ancillary data for assessment of uranium concentrations in groundwater, San Joaquin Valley, CA (ver. 1.1, December, 2019)

Metadata Updated: October 28, 2023

High concentrations of uranium were detected in samples from wells used for domestic drinking water supplies in the San Joaquin Valley. Of 163 domestic wells sampled by the California Groundwater Ambient Monitoring and Assessment Program Priority Basin Project (GAMA-PBP) and the National Water Quality Program (NWQP) in 2008-2015, 26 percent had uranium concentrations greater than the U.S. Environmental Protection Agency maximum contaminant level (EPA MCL) of 30 µg/L, with 13 percent of the wells having uranium concentration between 100 µg/L and 450 µg/L. To evaluate the potential anthropogenic and geologic causes of these anomalously high uranium concentrations, Rosen and others (2019) compiled water quality and ancillary data for 450 samples collected between 1993 and 2018 from 257 primarily domestic or public drinking water supply wells sampled by the USGS for GAMA-PBP or NWQP studies. Water-quality data compiled from the USGS NWIS database includes: field water-quality parameters (dissolved oxygen and pH), concentrations of major ions, trace elements, and nutrients, and tritium activities. Groundwater age and oxidation-reduction status classifications were derived from the water-quality data, and equilibrium saturation indices for minerals of interest were calculated from the water-quality data using PHREEQC. Ancillary data compiled for each well site include: well construction information, land use characteristics in 2001 and geologic characteristics. Rosen and others (2019) used graphical and spatial relations, statistical correlations, and principle component analysis to evaluate changes in uranium concentrations over time and infer processes responsible for occurrence of elevated uranium concentrations. They conclude that the process previously identified by Jurgens and others (2010) is responsible for a large part of the observed patterns of increasing uranium concentrations and occurrence of uranium concentrations greater than the EPA MCL - increased bicarbonate concentrations in recharge used for agricultural irrigation causes uranium sorbed on San Joaquin Valley sediments derived from Sierra Nevada granitic rocks to be become soluble. Rosen and others (2019) infer that in addition to solubility enhanced by bicarbonate, the highest uranium concentrations - which were found in the historic discharge zone at the distal end of regional groundwater flow system in the San Joaquin Valley - likely also reflect dissolution of reduced uranium minerals by the more oxic modern recharge water. All of the water-quality and ancillary data used by Rosen and others (2019) are presented in this Data Release. Rosen, M.R., Burow, K.R., and Fram, M.S., 2019 , Anthropogenic and geologic causes of anomalously high uranium concentrations in groundwater used for drinking water supply in the southeastern San Joaquin Valley, California: Journal of Hydrology, v. 577, ppg. 12409, Jurgens, B.C., Fram, M.S., Belitz, K., Burow, K.R., and Landon, M.K., 2010, Effects of groundwater development on uranium: Central Valley, California, USA: Ground Water, v. 48, p. 913-928,

Access & Use Information

Public: This dataset is intended for public access and use. License: No license information was provided. If this work was prepared by an officer or employee of the United States government as part of that person's official duties it is considered a U.S. Government Work.

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Metadata Created Date June 1, 2023
Metadata Updated Date October 28, 2023

Metadata Source

Harvested from DOI EDI

Additional Metadata

Resource Type Dataset
Metadata Created Date June 1, 2023
Metadata Updated Date October 28, 2023
Publisher U.S. Geological Survey
Identifier USGS:5ca25211e4b0b8a7f631715d
Data Last Modified 20200812
Category geospatial
Public Access Level public
Bureau Code 010:12
Metadata Context
Metadata Catalog ID
Schema Version
Catalog Describedby
Harvest Object Id 88f10507-464d-4308-97e8-072279494a8d
Harvest Source Id 52bfcc16-6e15-478f-809a-b1bc76f1aeda
Harvest Source Title DOI EDI
Metadata Type geospatial
Old Spatial -120.537,36.006,-118.966,37.145
Publisher Hierarchy White House > U.S. Department of the Interior > U.S. Geological Survey
Source Datajson Identifier True
Source Hash 560e18a2d432ec544567084ed9d0f9ef3c389bb31d92259546e70ea13c156321
Source Schema Version 1.1
Spatial {"type": "Polygon", "coordinates": -120.537, 36.006, -120.537, 37.145, -118.966, 37.145, -118.966, 36.006, -120.537, 36.006}

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