Arsenic and Uranium Occurrence in Private Wells in Connecticut, 2013–18—A Spatially Weighted and Bedrock Geology Assessment

Open-File Report 2020-1111
Prepared in cooperation with the Connecticut Department of Public Health
By:  and 

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Abstract

The U.S. Geological Survey, in cooperation with the Connecticut Department of Public Health, conducted a study to determine the presence of arsenic and uranium in private drinking water wells in Connecticut. Samples were collected during 2013–18 from wells completed in 115 geologic units, with 2,433 samples analyzed for arsenic and 2,191 samples analyzed for uranium. The study concluded four major findings.

  • In a spatially weighted analysis of groundwater samples collected from more than 2,000 private wells in bedrock aquifers in Connecticut, 3.9 percent of collected samples contained arsenic concentrations greater than the U.S. Environmental Protection Agency’s (EPA) maximum contaminant level (MCL) of 10 micrograms per liter (µg/L), and 4.7 percent of collected samples contained uranium concentrations greater than the EPA MCL of 30 µg/L.
  • Of the 2,433 water samples collected and analyzed from bedrock aquifers in Connecticut, 4.2 percent (102) contained arsenic concentrations at greater than 10 µg/L, and of the 2,191 water samples collected and analyzed from bedrock aquifers in Connecticut, 5.4 percent (118) contained uranium concentrations greater than 30 µg/L.
  • Uranium concentrations greater than or equal to 1 µg/L are relatively ubiquitous across the State of Connecticut, with these concentrations present in 44.9 percent of the State, according to spatially weighted statewide-scale proportion analysis.
  • Of the 115 geologic units studied, 44 had at least one sample with arsenic or uranium concentrations that exceeded the respective constituent’s EPA MCL.

Suggested Citation

Gross, E.L., and Brown, C.J., 2020, Arsenic and uranium occurrence in private wells in Connecticut, 2013–18—a spatially weighted and bedrock geology assessment: U.S. Geological Survey Open-File Report 2020–1111 (ver. 1.1, November 2020), 13 p., https://doi.org/10.3133/ofr20201111.

ISSN: 2331-1258 (online)

Study Area

Table of Contents

  • Acknowledgments
  • Abstract
  • Introduction
  • Arsenic and Uranium Concentration Data Sources
  • Arsenic and Uranium Concentrations in the State
  • Arsenic and Uranium Spatially Weighted Assessment
  • Arsenic and Uranium Occurrence in Relation to Bedrock Geology
  • References Cited

Additional publication details

Publication type Report
Publication Subtype USGS Numbered Series
Title Arsenic and uranium occurrence in private wells in Connecticut, 2013–18—A spatially weighted and bedrock geology assessment
Series title Open-File Report
Series number 2020-1111
DOI 10.3133/ofr20201111
Edition Version 1.0: October 2020; Version 1.1: November 2020
Year Published 2020
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) New York Water Science Center, Pennsylvania Water Science Center
Description Report: vi, 13 p.; Data Release
Country United States
State Connecticut
Online Only (Y/N) Y
Additional Online Files (Y/N) Y
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