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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.


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
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
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
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 Nivens; right: Copyright Lim H M)
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
#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 For more information on groundwater issues in the High Plains, consider...
Interactive Map of Water Resources in Georgia
#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 If you're interested in states' water resources, make sure to check...
Interactive Map of Oklahoma Water Resources
#MapOfTheDay! Today the Critical Issues Program (@AGI_GeoIssues) shared a map of water resources in Oklahoma from the Oklahoma Water Resources Board (@OKWaterBoard) 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
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
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
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


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...

Cover of Abandoned Wells

Introduction In 2017, there were one million active oil and gas wells in the United States.1 When a well reaches the end of its productive life, or if it fails to find economic quantities of oil or gas, the well operator is required by regulators to remove all equipment and plug the well to...


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...

Cover of Petroleum and the Environment - an Introduction

Introduction When oil and gas were first extracted and used on an industrial scale in the 19th century, they provided significant advantages over existing fuels: they were cleaner, easier to transport, and more versatile than coal and biomass (wood, waste, and whale oil). Diesel and gasoline...

Cover of Induced Seismicity from Oil and Gas Operations

Manmade Earthquakes Any activity that significantly changes the pressure on or fluid content of rocks has the potential to trigger earthquakes. This includes geothermal energy production, water storage in large reservoirs, groundwater extraction, underground injection of water for enhanced oil...


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....


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...

Cover of Using Produced Water

Opportunities and Concerns in Using Produced Water Produced water is natural groundwater that is extracted along with oil and gas. It is commonly salty and mixed with oil residues,1 so it must be either disposed of or treated and reused. About 2.5 billion gallons of produced water are extracted...

Cover of Water Sources for Hydraulic Fracturing

Hydraulic Fracturing and Water Demand Hydraulically fracturing a modern well can require millions of gallons of water for the initial fracturing process. This is a potential problem in arid regions with competing demands for fresh water (i.e. high water stress), such as Colorado and West Texas (...

Cover of Spills in Oil and Natural Gas Fields

Introduction Oilfield spills can harm wildlife and pose a risk to human health if they reach fresh water sources or contaminate soil or air. The enormous size of the oil and gas industry and the huge volumes of oil and produced water that are handled, stored, and transported result in thousands...

Cover of Water in the Oil and Gas Industry

Introduction The oil and gas industry consumes and produces water. Water is used to drill and hydraulically fracture (“frack”) wells, refine and process oil and gas, and produce electricity in some natural gas power plants. Water is also naturally present in the rocks that contain oil and gas...

Cover of Geoscientists in Petroleum and the Environment

Introduction Geoscience – the study of the Earth – underpins our understanding of the many intersections between petroleum and the environment, from the search for resources to the study of air pollutants. Without the work of geoscientists, we would have neither the energy system nor the...


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...

Cover of Groundwater Protection in Oil and Gas Production

Introduction The United States relies on groundwater for roughly 25% of its fresh water.1 This groundwater is found in porous, permeable rocks (aquifers) that often lie close to the Earth’s surface – the deepest freshwater aquifers are found more than 6,000 feet underground,2 but most are much...

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GOLI Online Courses

GOLI Course: Desalination as a Source of Fresh Water; Image credit: James Grellier, Licensed under Creative Commons, CC-BY-SA-3.0, via Wikimedia Commons.
Course Type: GOLI Online Course

Fresh water is an increasingly scarce resource in an increasingly populous and water-intensive world. Maintaining an adequate supply of fresh water both nationally and globally will be one of the largest challenges of the 21st century. Desalination of salty water – from both the ocean and the...

GOLI Course: Techniques for Developing High Resolution LNAPL Conceptual Site Models; Image courtesy of Roger Lamb
Course Type: GOLI Online Course

This course is intended for geologists involved in Light Non-Aqueous Phase Liquid (LNAPL) assessment and remediation. This course provides information on the development of high resolution conceptual site models that can be used to guarantee the project goals are met. The class will cover...

GOLI Course: Converting Membrane Interface Probe Sensor Results into VOC NAPL Distribution Information. Image courtesy of Roger Lamb
Course Type: GOLI Online Course

This course will focus on how to use Membrane Interface Probe sensor results in combination with soil and groundwater analytical results to map the distribution of volatile organic chemical non aqueous phase liquids. This course covers guidelines for using direct sensing tools such as the MIHPT...

GOLI Course: Water as One Resource; Image Copyright © Marli Miller, University of Oregon.
Course Type: GOLI Online Course

This course provides an overview of how groundwater and surface water interact, what the implications of these interactions on water resources are, and how water can be more effectively managed if an understanding of these interactions is incorporated.

The course presenters are Ken...

GOLI Course: Making Produced Water More Productive; Image credit: USGS/ Doug Duncan
Course Type: GOLI Online Course

Geoscience is essential to our understanding and management of produced water, an inevitable byproduct of oil and gas development. This course provides a scientific and regulatory background of produced water, how it is commonly disposed, what opportunities exist for the re-use of produced water...

Geological Surveys Database Publications

1905, Michigan Geological Survey

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1905, Michigan Geological Survey

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1908, Wisconsin Geological & Natural History Survey

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1911, Wisconsin Geological & Natural History Survey

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1912, Ohio Geological Survey

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1915, Oklahoma Geological Survey

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1915, Wisconsin Geological & Natural History Survey

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1916, Ohio Geological Survey

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1918, Arizona Geological Survey

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1922, Wisconsin Geological & Natural History Survey

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