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USGS Groundwater Watch

USGS maintains a network of active wells to provide basic statistics about groundwater levels.

 [Image: USGS active water level wells location map.]

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USGS Groundwater Information > National Groundwater Awareness Week 2014


 [National Groundwater Awareness Week logo]

USGS Recognizes "National Groundwater Awareness Week," March 9-15, 2014

The U.S. Geological Survey (USGS) joins our community partners in recognizing March 9-15, 2014, as National Groundwater Awareness Week because groundwater is important to all of us!

Did you know...

25% of global fresh water is estimated to be stored as groundwater. (1)

42% of US irrigation withdrawals came from groundwater in 2005. (2)

33% of US public-supply withdrawals came from groundwater in 2005. (3)

23% of US withdrawals from all aquifers for irrigation, public-supply, and self-supplied industrial water uses combined in 2000 were from just one aquifer, the High Plains Aquifer. (4)

20% of Nation's groundwater withdrawals were from the California Central Valley aquifer system. (5)

On average, greater than 50% of streamflow may be contributed by groundwater. In some cases, groundwater contribution to streamflow may be as high as 90%. Groundwater also is a major source of water to lakes and wetlands. (6)


 [Groundwater well]

Groundwater: A Valuable Resource

Groundwater is one of the Nation's most valuable natural resources. It occurs almost everywhere beneath the Earth's surface and is a major source of water supply worldwide. It is the Nation's principal reserve of freshwater and represents much of the potential future water supply. Groundwater is a major contributor to flow in many streams and has a strong influence on river and wetland habitats for plants and animals.

At the USGS we observe and monitor groundwater conditions at locations across the United States. USGS scientists work constantly to improve our understanding of how groundwater moves through the subsurface and what human and natural factors affect the quantity and quality of that groundwater.

 [Public supply well]

How much groundwater do we use?

In the year 2005 (7):

  • The US pumped an estimated 79.6 billion gallons of fresh groundwater a day.
  • 18% of fresh groundwater withdrawals were for public supply.
  • 98% of the US population providing their own household water obtained their supplies from groundwater sources.
  • 67% of fresh groundwater withdrawals were for irrigation.
  • More than half of fresh groundwater withdrawals in the United States occurred in six States.
  • In California, Texas, Nebraska, Arkansas, and Idaho, most of the fresh groundwater withdrawals were for irrigation.
  • In Florida, 52% of all fresh groundwater withdrawals were for public supply, and 34% were for irrigation.

The USGS works in cooperation with local, State, and Federal environmental agencies to collect water-use information. Every five years, data at the county level are compiled into a national water-use data system, and state-level data are published in a national circular. USGS water-use data and publications are available online.

 [Photo of well pad raised above land surface due to land subsidence]

What is a groundwater drought?

A drought is a period of drier-than-normal conditions that results in water-related problems. A groundwater drought typically refers to a period of decreased groundwater levels that results in water-related problems. The amount of groundwater decline that would be considered a drought varies regionally due to differences in groundwater conditions and groundwater needs for humans and the environment.

Groundwater is important during all hydrologic droughts. For example, groundwater might serve as a supplemental source of water during surface-water drought. Reduced groundwater levels due to drought or increased pumping during drought can lower water levels and decrease flows in streams. Reduced water levels in aquifers can result in land subsidence.

The USGS provides resource managers and policy makers with unbiased knowledge about groundwater to support their planning for and response to drought. Learn more about groundwater and drought and about USGS contributions to our understanding of groundwater and drought.

 [USGS groundwater scientists install sampling probe.]  [USGS scientist removes packer from well.]  [USGS personnel operate a drill rig.]  [USGS scientist measures groundwater level.]  [USGS scientist records the location of a well.]
 [Photo of person standing next to sign in the desert]

The USGS erected desert watering place signposts starting around 1917 or 1918. (Modified from Follansbee, 1994)

135 Years of Science for the Nation

The USGS celebrated its 135th anniversary on March 3, 2014. On March 3, 1879, the 45th Congress and President Hayes agreed to promote governmental economy and efficiency by forming a single, united U.S. Geological Survey. They made the new organization responsible for the scientific "classification of the public lands and examination of the Geological Structure, mineral resources and products of the national domain." Although many people only associate the early Geological Survey with mapping and mining of the West, the USGS was studying groundwater as early as the 1890s!

Today, the USGS partners with federal, state, and local partners to improve our understanding of our groundwater resources. Using data collected by USGS and cooperating agencies along with software and other tools developed by USGS scientists, USGS predicts long- and short-term changes to groundwater conditions as part of local and regional groundwater studies. We deliver the results of our observations, improved understanding, and predictions through journal articles, USGS reports, online databases, presentations at scientific meetings, and our web sites. These USGS tools, information, and data are used every day by water-resource managers, regulators, policy makers, well operators, and others to make decisions about how best to protect our groundwater to meet current and future needs.

Learn more about the history of the USGS and our water studies:

852,118 Groundwater Sites

In order to protect our groundwater, we must understand how groundwater flows through the ground. USGS scientists conduct studies to help us understand what affects groundwater movement through the subsurface. We study how quickly groundwater moves, where it flows in the subsurface, how it interacts with subsurface materials that surround it, and other important questions. Collecting groundwater levels at selected observation wells over time -- sometimes for decades or more -- is one important task.

Data from wells that have been part of USGS studies are available online for public download and use through our National Water Information (NWIS) web site, an online database.


NWIS includes groundwater level data from:

  • 852,118 wells, springs, test holes, tunnels, drains, and excavations (8)
  • 18,729 wells where water levels were measured at least once in the last year (9)
  • 1,423 wells where real-time continuous water-level data are transmitted from the site to the USGS at least once per day, usually by satellite or telephone (10)

You can view basic statistics about water-level data measured in the last year or access and download data through NWIS database map interface.


30 Years of MODFLOW: Modeling Groundwater Flow

USGS scientists create computer programs to simulate or predict groundwater flow conditions over time. Originally published in 1984, MODFLOW is the USGS's three-dimensional (3D) finite-difference groundwater model. MODFLOW is considered an international standard for simulating and predicting groundwater conditions and groundwater/surface-water interactions. Originally developed and released solely as a groundwater-flow simulation code, MODFLOW's modular structure has provided a robust framework for integration of additional simulation capabilities that build on and enhance its original scope.


MODFLOW and related programs are used by by government, university, and industry scientists and water-resource managers around the world. The MODFLOW family of software programs are open source and freely available for download:



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Page Last Modified: Thursday, 06-Mar-2014 16:49:27 EST