What is groundwater?
Groundwater is water that exists underground in saturated zones beneath the land surface. The upper surface of the saturated zone is called the water table.
Contrary to popular belief, groundwater does not form underground rivers. It fills the pores and fractures in underground materials such as sand, gravel, and other rock, much the same way that water fills a sponge. If groundwater flows naturally out of rock materials or if it can be removed by pumping (in useful amounts), the rock materials are called aquifers.
Groundwater moves slowly, typically at rates of 7-60 centimeters (3-25 inches) per day in an aquifer. As a result, water could remain in an aquifer for hundreds or thousands of years. Groundwater is the source of about 40 percent of water used for public supplies and about 39 percent of water used for agriculture in the United States.
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Estimated groundwater withdrawals from principal aquifers in the United States, 2015
In 2015, about 84,600 million gallons per day (Mgal/d) of groundwater were withdrawn in the United States for various uses including public supply, self-supplied domestic, industrial, mining, thermoelectric power, aquaculture, livestock, and irrigation. Of this total, about 94 percent (79,200 Mgal/d) was withdrawn from principal aquifers, which...
Lovelace, John K.; Nielsen, Martha G.; Read, Amy L.; Murphy, Chid J.; Maupin, Molly A.
Water priorities for the nation—The U.S. Geological Survey next generation water observing system
The challenges of providing safe and sustainable water supplies for human and ecological uses and protecting lives and property during water emergencies are well recognized. The U.S. Geological Survey (USGS) plays an essential role in meeting these challenges through its observational networks and renowned water science and research activities (...
Eberts, Sandra M.; Wagner, Chad R.; Woodside, Michael D.
The quality of our Nation's waters: Water quality in principal aquifers of the United States, 1991-2010
About 130 million people in the United States rely on groundwater for drinking water, and the need for high-quality drinking-water supplies becomes more urgent as our population grows. Although groundwater is a safe, reliable source of drinking water for millions of people nationwide, high concentrations of some chemical constituents can pose...
DeSimone, Leslie A.; McMahon, Peter B.; Rosen, Michael R.
Groundwater studies: principal aquifer surveys
In 1991, the U.S. Congress established the National Water-Quality Assessment (NAWQA) program within the U.S. Geological Survey (USGS) to develop nationally consistent long-term datasets and provide information about the quality of the Nation’s streams and groundwater. The USGS uses objective and reliable data, water-quality models, and systematic...
Burow, Karen R.; Belitz, Kenneth
The quality of our Nation's waters-Nutrients in the Nation's streams and groundwater, 1992-2004
National Findings and Their ImplicationsAlthough the use of artificial fertilizer has supported increasing food production to meet the needs of a growing population, increases in nutrient loadings from agricultural and, to a lesser extent, urban sources have resulted in nutrient concentrations in many streams and parts of aquifers that exceed...
Dubrovsky, Neil M.; Burow, Karen R.; Clark, Gregory M.; Gronberg, JoAnn M.; Hamilton, Pixie A.; Hitt, Kerie J.; Mueller, David K.; Munn, Mark D.; Nolan, Bernard T.; Puckett, Larry J.; Rupert, Michael G.; Short, Terry M.; Spahr, Norman E.; Sprague, Lori A.; Wilber, William G.
Ground-Water Availability in the United States
Ground water is among the Nation's most important natural resources. It provides half our drinking water and is essential to the vitality of agriculture and industry, as well as to the health of rivers, wetlands, and estuaries throughout the country. Large-scale development of ground-water resources with accompanying declines in ground-water...
Reilly, Thomas E.; Dennehy, Kevin F.; Alley, William M.; Cunningham, William L.
Pesticides in the nation's streams and ground water, 1992-2001 - a summary
Gilliom, Robert J.; Hamilton, Pixie A.
Sustainability of ground-water resources
The pumpage of fresh ground water in the United States in 1995 was estimated to be approximately 77 billion gallons per day (Solley and others, 1998), which is about 8 percent of the estimated 1 trillion gallons per day of natural recharge to the Nation's ground-water systems (Nace, 1960). From an overall national perspective, the ground-water...
Alley, William M.; Reilly, Thomas E.; Franke, O. Lehn
Ground water and surface water: A single resource
The importance of considering ground water and surface water as a single resource has become increasingly evident. Issues related to water supply, water quality, and degradation of aquatic environments are reported on frequently. The interaction of ground water and surface water has been shown to be a significant concern in many of these issues....
Winter, Thomas C.; Harvey, Judson W.; Franke, O. Lehn; Alley, William M. Ground water: the hidden resource
Ground water is water underground in saturated zones beneath the land surface. Contrary to popular belief, ground water does not form underground "rivers." It fills the pores and fractures in underground materials such as sand, gravel, and other rock. If ground water flows from rock materials or can be removed by pumping from the saturated rock...
Vandas, Stephen; Farrar, Frank Ground water and the rural homeowner
As the salesmen sang in the musical The Music Man, "You gotta know the territory." This saying is also true when planning to buy or build a house. Learn as much as possible about the land, the water supply, and the septic system of the house before buying or building. Do not just look at the construction aspects or the beauty of the home and...
Waller, Roger M.
Water resources professional's outreach notebook; ground water, grade level 6-8
Vandas, S.J.
Alaska Earthquake Rattles Florida’s Groundwater Plumbing
At 12:32 am Alaska time on January 23, 2018, a magnitude 7.9 earthquake shook Alaska residents out of their beds and set off fears of a tsunami all down the West Coast. Fortunately, the tsunami was only a few inches in height, but within an hour of the earthquake in Alaska, waves of a different sort were hitting far away in Florida.
The Quality of the Nation’s Groundwater: Progress on a National Survey
The U.S. Geological Survey is near the midpoint of a complex undertaking to survey the quality of the nation’s largest drinking-water resource.
Current website: https://www.usgs.gov/news/quality-nation-s-groundwater-progress-a-nation...
Study Estimates about 2.1 Million People using Wells High in Arsenic
Most Arsenic Presumed to be From Naturally Occurring Sources
High Levels of Radon Found in Some Wells Across Pennsylvania
A new U.S. Geological Survey study has discovered high levels of radon in wells across certain areas of Pennsylvania.
How Well Do You Know Groundwater
Groundwater, which flows out of sight through aquifers beneath our feet, is one of the Nation’s most important natural resources. In recognition of National Groundwater Awareness Week, March 5–11, 2017, here’s an opportunity to put your knowledge of this vital resource to the test!
Groundwater Quality in Eastern U.S.
A regional assessment of untreated groundwater in the combined Valley and Ridge and Piedmont and Blue Ridge aquifers in the eastern United States is now available from the U.S. Geological Survey.
How Much Water Do We Use?
The USGS National Water-Use Science project has documented 60 years of water-use from 1950 to 2010 in an interactive map. Choose a year and pick a category to see how much water your state uses.
Large Precipitation Events are Critical in Replenishing Groundwater Resources
Large precipitation events that occur about every 10 years are a critical source of recharge for replenishing groundwater resources, according to a new study by the U.S. Geological Survey and the Bureau of Reclamation.
High Plains Aquifer Groundwater Levels Continue to Decline
The U.S. Geological Survey has released a new report detailing changes of groundwater levels in the High Plains Aquifer. The report presents water-level change data in the aquifer for two separate periods: from 1950 – the time prior to significant groundwater irrigation development – to 2013, and 2011 to 2013.
Groundwater-Level Measurement near Jewel Cave National Monument, SD
USGS groundwater hydrologist, Bill Eldridge, is lowering a transducer into an observation well near Jewel Cave National Monument to monitor water-level changes in the Madison aquifer. The data collected will be used to update previously published groundwater-altitude maps to help better understand groundwater flow. The work is being conducted in cooperation with the
...
Collecting groundwater quality sample
With property owner's permission, a USGS hydrologist collects a water sample from a private well in Gem County, Idaho
Measuring the groundwater level in a well near Lame Deer, Montana
Measuring the groundwater level in a well near Lame Deer, Montana
Potential Corrosivity of Untreated Groundwater in the United States
- Corrosive groundwater, if untreated, can dissolve lead and other metals from pipes.
- National maps have been prepared to identify the occurrence of potentially corrosive groundwater in the U.S.
- These findings have the greatest implication for the 44 million people dependent on domestic wells for drinking water.
Groundwater gage in Indiana
USGS scientist tests groundwater samples for water quality.
USGS scientist tests groundwater samples for water quality.
The USGS is near the midpoint of a complex undertaking to survey the quality of the nation’s largest drinking-water resource. From 2012 – 2023, the USGS is assessing groundwater throughout the country through extensive sampling. The latest results from five regional aquifers are now available.
Setting up Groundwater Streamgage on Green River nr LaBarge
Setting up Groundwater Streamgage on Green River nr LaBarge
PubTalk 9/2011 — Tracking the Nation's Groundwater Reserves
--issues facing current and future water supplies
by William Alley, USGS Office of Groundwater
- Ground water is among the Nation's most important natural resources, providing half of our drinking water as well as being essential to agriculture and industry, and the health of ecosystems throughout the country
Real-time Groundwater Streamgage equipment set up
Real-time Groundwater Streamgage equipment set up
Groundwater Monitoring
Data recorder in a field well shelter monitoring a well in New Jersey