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Water supplies for household use and irrigated agriculture rely on groundwater wells. When wells are drilled into a highly pressurized aquifer, groundwater may flow up the well and onto the land surface without pumping. These flowing artesian wells were common in the early 1900s in the United States before intensive groundwater withdrawals began, but their present-day prevalence remains unknown. Here, we compile and analyze ten thousand well water observations made more than a century ago. We show that flowing artesian conditions characterized ~61% of wells tapping confined aquifers before 1910, but only ~4% of wells tapping confined aquifers today. This pervasive loss of flowing artesian conditions evidences a widespread depressurization of confined aquifers after a century of intensive groundwater use in the United States. We conclude that this depressurization of confined aquifers has profoundly changed groundwater storage and flow, increasing the vulnerability of deep aquifers to pollutants and contributing to land subsidence.
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This content will become publicly available on March 30, 2026
Testing different scenarios of freshwater emplacement on the New England continental shelf using hydrologic modeling constrained by electromagnetic, isotopic, and salinity data
Recent advances in marine electromagnetic surveys have allowed geophysicists to interpret and map offshore freshwater resources with unprecedented resolution and to test inferences regarding onshore-offshore hydrologic connections. To date, however, little is known about the timing or isotopic composition of this unconventional water resource. Here, we reconstructed the Pleistocene hydrogeology of the U.S. Atlantic continental shelf using a cross-sectional paleo-hydrogeologic model to explore possible mechanisms and timing of freshwater emplacement offshore Martha’s Vineyard, Massachusetts. We considered two scenarios in which the Laurentide ice sheet extended different distances offshore, and a third scenario without any ice sheet. The hydrostratigraphic framework was constructed by integrating borehole lithology data, seismic data, and formation resistivity data. Model results were compared to formation resistivity data as well as borehole salinity, groundwater residence time, and stable isotope profiles. Neither of the ice-sheet scenarios provided a significantly better fit to the onshore isotopic and offshore salinity observations than the third scenario. All three model scenarios predicted freshwater emplacement within Tertiary and Cretaceous units. Pleistocene deposits were largely devoid of freshened groundwater. Simulated groundwater residence times for the midshelf region ranged between 104 and 106 yr at depths of <500 m. Simulated groundwater ages from wells completed within Pleistocene confined aquifers are consistent with measured groundwater ages within confined aquifers of Martha’s Vineyard and Nantucket Island (2750−5900 yr). Analysis of onshore 3H/3He dating data indicates that some wells contain a mixture of old and modern (<60 yr) groundwater. Calculated fossil groundwater in the midshelf region that included ice-sheet loading retained relatively low δ18O values, consistent with glacial meltwater recharge. Model results suggest that much of the freshwater emplacement occurred within the last glacial cycle and that the island and offshore hydrogeologic systems appear to be connected.
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- Award ID(s):
- 1925974
- PAR ID:
- 10609868
- Publisher / Repository:
- Geological Society of America
- Date Published:
- Journal Name:
- Geological Society of America bulletin
- ISSN:
- 0016-7606
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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