Groundwater

Groundwater is the water found underground in the cracks and spaces in soil, sand, and rock. Groundwater has been used by humans for thousands of years; today it provides 25% of the fresh water used in the United States, mostly for irrigation and public water supplies.

Basics

Water well in New York. Image Credit: Wikimedia Commons user Wknight94

Groundwater is an inevitable result of gravity: if surface water can seep into the ground before it evaporates or flows away, it will. Water also flows through rocks underground and may flow out of the ground into streams, rivers, lakes, or the ocean in places where the land surface is lower than the water table (e.g., at the bottom of a valley or the side of a cliff) – these outflows of groundwater are commonly called “springs”. In this way, surface water and groundwater are intimately linked – in some places, changes in groundwater levels can have major effects on the levels of nearby rivers and lakes, and vice versa.   Read more

Frequently Asked Questions

Latest News

U.S. Geological Survey's (USGS) map of groundwater depletion
(2017-03-06)
It's Groundwater Awareness Week 2017 (#GWAwarenessWeek if you're on twitter)! Today's Critical Issues Map of the Day from the USGS and shows the cumulative depletion of groundwater for 40 aquifer systems across the U.S (excluding Alaska). The map depicts depletion over the time period of 1900 to...
Atlean Lake in British Columbia
(2016-11-29)
November 10, 2016 The U.S. Geological Survey (USGS) has announced a new grant program that will award up to $2 million in cooperative agreements for new state and local water resource agencies participating in the National Groundwater Monitoring Network (NGWMN). The funds will be used to provide...
Hawaiian flower
(2016-11-03)
October 18, 2016 On October 18, the Senate Committee on Energy and Natural Resources held a hearing at the Hawaiian State Capitol in Honolulu. The hearing addressed current water resource scarcity issues facing the state and recent water legislation. Hawaii‘s freshwater supplies are drawn almost...
Irrigation equipment. (Background: Copyright Shutterstock.com/Sergey Nivens; right: Copyright Shutterstock.com/Cecilia Lim H M)
(2016-10-28)
The 2016 Critical Issues Forum, Addressing Changes in Regional Groundwater Resources: Lessons from the High Plains Aquifer concluded today at the Colorado School of Mines Ben H. Parker Student Center. An initial summary of social media posts using #CIForum16 were compiled connecting people to...
Interactive map of water wells in Nebraska. Image Credit: Nebraska Department of Natural Resources
(2016-10-14)
#MapOfTheDay! Today the Critical Issues Program (@AGI_GeoIssues) shared an interactive map of water wells in Nebraska from the Nebraska Department of Natural Resources (@NebraskaDNR), which you can find at bit.ly/22dbeyi. For more information on groundwater issues in the High Plains, consider...
Interactive Map of Water Resources in Georgia
(2016-09-15)
#MapOfTheDay! Today the Critical Issues Program (@AGI_GeoIssues) shared a map of water resources in Georgia from the Georgia Soil & Water Conservation Commission (@GASoilandWater), which you can find at http://bit.ly/2bZ7px8. If you're interested in states' water resources, make sure to check...
Interactive Map of Oklahoma Water Resources
(2016-09-07)
#MapOfTheDay! Today the Critical Issues Program (@AGI_GeoIssues) shared a map of water resources in Oklahoma from the Oklahoma Water Resources Board (@OKWaterBoard) http://bit.ly/2bIKFDO. If you liked this map make sure to check out the next Critical Issues Forum on the High Plains/Ogallala...
Flyer for the Free Desalination as a Source of Fresh Water Webinar
(2016-09-01)
The American Geosciences Institute Critical Issues Program, along with the National Ground Water Association, the Association of Environmental & Engineering Geologists, and the U.S. Chapter of the International Association of Hydrogeologists will be hosting a free webinar titled, "Desalination...
Drilling rig
(2016-08-25)
August 11, 2016 The Environmental Protection Agency’s (EPA) Science Advisory Board (SAB) released its final report assessing EPA’s recent study of potential impacts of hydraulic fracturing for oil and gas on drinking water resources. Congress requested the study in 2009, and EPA released its draft...
Atlean Lake in British Columbia
(2016-03-10)
February 24, 2016 The House Committee on Natural Resources, Subcommittee on Water, Power, and Oceans held a hearing to discuss the state of California’s water supply. The hearing centered on the main reasons for the decreased water supply in California, with some witnesses pointing to the El Niño-...

Case Studies & Factsheets

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Why water storage? A reliable water supply is essential for economic, environmental, and public health, but natural water supplies vary with the seasons and between years. Water storage, whether in reservoir lakes or underground, helps to ensure that water is available even during droughts....

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The Need for Groundwater Management: Sustaining water supplies and preventing hazards In California, surface water from rainfall, snowmelt, and distant rivers rarely meets the state’s urban and agricultural water needs. Groundwater is an essential water source, providing 35% of the fresh water...

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Introduction Dry wells improve stormwater drainage and aquifer recharge by providing a fast, direct route for rainwater to drain deep into underlying sediment and rock. Dry wells are most common in the western U.S. where clay or caliche layers slow down the natural drainage of water into...

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What is a Dry Well? A dry well is a well that is used to transmit surface water underground and is deeper than its width at the surface (see image, below). Most dry wells are 30 to 70 feet deep and 3 feet wide at the surface. They are lined with perforated casings and can be filled with gravel...

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Fresh water from underground Groundwater is any water found underground in the cracks and pores in soil, sand, or rock. Groundwater provides 25% of the fresh water used in the United States.1 It is particularly important for irrigation and domestic uses in arid or remote areas, where surface...

Research Database Publications

Cover image of position paper; Image credit: NGWA
2017, National Ground Water Association (NGWA)
Groundwater, a basic life-sustaining and economic resource, must be managed locally through best practices of states and local governments and their residents and businesses recognizing the range of domestic, municipal, industrial, ecological, and agricultural uses it supports for their communities...
Cover for ES05; Source: Wisconsin Geological & Natural History Survey
2010, Wisconsin Geological & Natural History Survey (WGNHS)
In an average year, the county receives about 35 inches of rain and snow. Of that, about 11 inches reaches the water table. In a very wet year, when as much as 49 inches of precipitation may fall in the county, the estimated average recharge rate is about 15 inches per year. During very dry years,...
Cover for USGS FS 2013-3042 ; Source: USGS
2014, U.S. Geological Survey (USGS)
Arkansas is the fourth largest user of groundwater in the United States, where groundwater accounts for two-thirds of the total water use. Groundwater use in the State increased by 510 percent between 1965 and 2005 (Holland, 2007). The Arkansas Groundwater-Quality Network is a Web map interface (...
Cover of factsheet; Image credit: IAH
2015, International Association of Hydrogeologists (IAH)
Urbanisation is the predominant global phenomenon of our time, and groundwater from springs and wells has been a vital source of urban water-supply since the first settlements. In the modern era, groundwater capture using deep waterwells with submersible electric pumps has enabled major growth for...
Fig. 1 - The geologic map of part of the Pell City quadrangle, AL, accurately identifies the recharge area of the Fort Payne Chert aquifer (medium blue) that must be protected from pollution. Credit: W. Thomas
2004, American Geosciences Institute (AGI)
In central Alabama, the Mississippian-age Fort Payne Chert is an important aquifer for domestic and municipal water supplies. Geologic mapping shows the extent of Fort Payne Chert exposure at the ground surface, which is the recharge area for the aquifer. Planning for protection of the groundwater...
Cover image for WFS 2008-6 ; Source: Iowa Geological Survey
2008, Iowa Geological Survey (IGS)
Although groundwater by its very nature is hidden and not easily accessible for sampling, there are still plenty of reasons to be concerned about groundwater quality. You may swim or fish in one of Iowa’s surface water bodies during the summer, but there is a high probability that you drink...
Cover of USGS_2015-3084, Source: U.S. Geological Survey
2015, U.S. Geological Survey (USGS)
The U.S. Geological Survey (USGS) uses data collection, modeling tools, and scientific analysis to help water managers plan for, and assess, hydrologic issues that can cause “undesirable results” when associated with groundwater use. This information helps managers understand trends and investigate...
Cover of factsheet; Image credit: IAH
2016, International Association of Hydrogeologists (IAH)
The naturally high microbiological and chemical quality of groundwater, captured at springheads and in shallow galleries and dugwells, has been vital for human survival, wellbeing and development from our earliest history – and remains so today. The purity of groundwater, coupled with its mineral...
Cover of factsheet; Image credit: IAH
2016, International Association of Hydrogeologists (IAH)
Groundwater (contained in sediments and rocks) constitutes the planet’s predominant reserve of fresh water, commonly with storage times from decades to centuries and millennia. Groundwater resources thus provide an excellent ‘buffer’ against the effects of climate variability on surface-water...
Cover image for WFS 2001-13 ; Source: Iowa Geological Survey
2001, Iowa Geological Survey (IGS)
For many Iowans, not much thought is given to the water coming from the kitchen faucet. Where did this water originate? How old is it? Is it safe to drink? For approximately 79 percent of Iowans, the water in their drinking glass is groundwater.