Groundwater wells are critical infrastructure that enable the monitoring, extraction, and use of groundwater, which has important implications for the environment, water security, and economic development. Despite the importance of wells, a unified database collecting and standardizing information on the characteristics and locations of these wells across the United States has been lacking. To bridge this gap, we have created a comprehensive database of groundwater well records collected from state and federal agencies, which we call the United States Groundwater Well Database (USGWD). Presented in both tabular form and as vector points, USGWD comprises over 14.2 million well records with attributes, such as well purpose, location, depth, and capacity, for wells constructed as far back as 1763 to 2023. Rigorous cross-verification steps have been applied to ensure the accuracy of the data. The USGWD stands as a valuable tool for improving our understanding of how groundwater is accessed and managed across various regions and sectors within the United States.
This content will become publicly available on September 15, 2024
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.
more » « less- Award ID(s):
- 2048227
- NSF-PAR ID:
- 10487939
- Publisher / Repository:
- Science Advances
- Date Published:
- Journal Name:
- Science Advances
- Volume:
- 9
- Issue:
- 37
- ISSN:
- 2375-2548
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Many individual measurement points are required to characterize groundwater velocity within an aquifer. Groundwater velocity is most commonly measured using a network of >5 cm diameter monitoring wells, which, if not already present at a site, are expensive and labor‐intensive to install. Drive‐point piezometers—simple, cost‐effective wells that can be installed by hand—are a common tool for sampling groundwater in shallow, alluvial aquifers, but most groundwater velocity measurement techniques require equipment that is too large for these narrow (usually <2 cm inside diameter) piezometers. In this technical note, we introduce a low‐cost sensor and well packer system (<$90 USD) for performing point dilution tests in narrow piezometers. Field data show that the magnitude of groundwater velocity measured with this technique agrees with velocities computed from natural gradient tracer tests. Additionally, with proper calibration, these sensors can be used to continuously monitor in‐well specific conductance, either during inter‐well tracer tests with saline tracers or for water quality monitoring. This system is a viable tool for rapid assessment of the magnitude of groundwater velocity in shallow aquifers.
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Abstract Most stored groundwater is ‘fossil’ in its age, having been under the ground for more than ~12 thousand years. Mapping where wells tap fossil aquifers is relevant for water quality and quantity management. Nevertheless, the prevalence of wells that tap fossil aquifers is not known. Here we show that wells that are sufficiently deep to tap fossil aquifers are widespread, though they remain outnumbered by shallower wells in most areas. Moreover, the proportion of newly drilled wells that are deep enough to tap fossil aquifers has increased over recent decades. However, this widespread and increased drilling of wells into fossil aquifers is not necessarily associated with groundwater depletion, emphasizing that the presence of fossil groundwater does not necessarily indicate a non-renewable water supply. Our results highlight the importance of safeguarding fossil groundwater quality and quantity to meet present and future water demands.
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Abstract Marine tracer studies indicate that large volumes of saline groundwater discharge to the ocean in passive margin settings. These results have not found widespread recognition because the location and cause(s) of this submarine groundwater discharge (SGD) are unclear. Here we report observations from a new long‐term seafloor monitoring network in the South Atlantic Bight that support large‐scale SGD far from shore. In the study area near Charleston, South Carolina, we determined hydrostratigraphy via vibracoring and chirp seismic surveys, collected water samples from seafloor wells, and used heat as a tracer to monitor SGD. We detected significant pulses of saline SGD issuing from the seafloor 10–15 km from shore. These pulses coincided with abrupt sea level declines of up to 30 cm. Based on an analysis of marine conditions at the time, we propose that upwelling‐favorable winds depressed sea level in the region, causing saline groundwater to discharge from confined coastal aquifers that connect land and ocean. The combination of stacked confined aquifers and variations in sea level are nearly ubiquitous in passive coastal margins. This previously overlooked combination can explain a wide range of other published observations and promotes more dynamic flows than simple tidal fluctuations. This new mechanism may explain Ra tracer signals in the coastal Atlantic Ocean and supports significant nutrient inputs to the ocean. These large natural geochemical fluxes may be sensitive to groundwater usage on land.
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Abstract Groundwater flow direction within the critical zone of headwater catchments is often assumed to mimic land surface topographic gradients. However, groundwater hydraulic gradients are also influenced by subsurface permeability contrasts, which can result in variability in flow direction and magnitude. In this study, we investigated the relationship between shallow groundwater flow direction, surface topography, and the subsurface topography of low permeability units in a headwater catchment at the Hubbard Brook Experimental Forest (HBEF), NH. We continuously monitored shallow groundwater levels in the solum throughout several seasons in a well network (20 wells of 0.18–1.1 m depth) within the upper hillslopes of Watershed 3 of the HBEF. Water levels were also monitored in four deeper wells, screened from 2.4 to 6.9 m depth within glacial drift of the C horizon. We conducted slug tests across the well network to determine the saturated hydraulic conductivity (
K sat) of the materials surrounding each well. Results showed that under higher water table regimes, groundwater flow direction mimics surface topography, but under lower water table regimes, flow direction can deviate as much as 56 degrees from surface topography. Under these lower water table conditions, groundwater flow direction instead followed the topography of the top of the C horizon. The interquartile range ofK satwithin the C horizon was two orders of magnitude lower than within the solum. Overall, our results suggest that the land surface topography and the top of the C horizon acted as end members defining the upper and lower bounds of flow direction variability. This suggests that temporal dynamics of groundwater flow direction should be considered when calculating hydrologic fluxes in critical zone and runoff generation studies of headwater catchments that are underlain by glacial drift.
