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Over a third of groundwater in USA public-supply aquifers is Anthropocene-age and susceptible to surface contamination

July 1, 2022

The distribution of groundwater age is useful for evaluating the susceptibility and sustainability of groundwater resources. Here, we compute the aquifer-scale cumulative distribution function to characterize the age distribution for 21 Principal Aquifers that account for ~80% of public-supply pumping in the United States. The aquifer-scale cumulative distribution function for each Principal Aquifer was derived from an ensemble of modeled age distributions (~60 samples per aquifer) based on multiple tracers: tritium, tritiogenic helium-3, sulfur hexafluoride, chlorofluorocarbons, carbon-14, and radiogenic helium-4. Nationally, the groundwater is 38% Anthropocene (since 1953), 34% Holocene (75 – 11,800 years ago), and 28% Pleistocene (>11,800 years ago). The Anthropocene fraction ranges from <5 to 100%, indicating a wide range in susceptibility to land-surface contamination. The Pleistocene fraction of groundwater exceeds 50% in 7 eastern aquifers that are predominately confined. The Holocene fraction of groundwater exceeds 50% in 5 western aquifers that are predominately unconfined. The sustainability of pumping from these Principal Aquifers depends on rates of recharge and release of groundwater stored in fine-grained layers.

Citation Information

Publication Year 2022
Title Over a third of groundwater in USA public-supply aquifers is Anthropocene-age and susceptible to surface contamination
DOI 10.1038/s43247-022-00473-y
Authors Bryant Jurgens, Kirsten Faulkner, Peter B. McMahon, Andrew Hunt, Gerolamo C. Casile, Megan B. Young, Kenneth Belitz
Publication Type Article
Publication Subtype Journal Article
Series Title Nature Communications Earth & Environment
Index ID 70234209
Record Source USGS Publications Warehouse
USGS Organization California Water Science Center, Colorado Water Science Center