Uranium and Arsenic Contamination of Groundwater on Navajo and Hopi Nations

Introduction: Up to 30% of homes on Native American lands do not have safe drinking water and there is therefore a reliance on unregulated wells. Our purpose was to test whether the quality of the groundwater in these wells is contaminated by uranium and arsenic . Methods: We obtained 218 water samples between 2013 and 2015 from 164 wells identified by community members across the Navajo and Hopi Nations. Samples in 2015 (n=6) were taken only from wells with elevated uranium and arsenic levels to confirm elevated levels. Uranium and arsenic concentrations were measured using an inductively coupled plasma mass spectrometer. Well depth was known for 21% of samples. Geographic coordinates were obtained for all wells and 30-day average and cumulative precipitation data were obtained from the National Oceanic and Atmospheric Administration. Results: Mean uranium concentration (±1SD) was 9.9±21.4 µg/L and mean arsenic concentration was 8.2±15.1 µg/L. Nearly 26% of wells had concentrations exceeding United State...