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Information Briefs

NGWA has developed this series of information briefs on issues as they relate to groundwater.

Brackish Groundwater

Brackish water does not have an exact definition, but it is typically defined as distastefully salty, but less saline than seawater (between 1,000 to 10,000 ppm [parts per million] in total dissolved solids [TDS]).  In addition to certain surface water settings such as estuaries, brackish water can be found in aquifers.  In some regions of the country with limited availability of freshwater, desalination of brackish groundwater is being used as an alternative supply.  Read more about brackish groundwater.

Declaration of the Global Importance of Groundwater

NGWA invites others to join with it in recognizing that, given groundwater’s vast reserves and broad geographical distribution, its generally good quality, and its protection from seasonal fluctuations and contamination, groundwater holds the promise to ensure future world communities an affordable and safe water supply.  Further, by recognizing that both surface water and groundwater constitute essential resources, thoroughly integrated water resources management strategies will serve to enhance the security, reliability, and quality of the world’s water supplies.  ​Read more about the global importance of groundwater.

Domestic Water Well Exemption in the Western United States

Most Western states have laws or regulations allowing landowners to install private wells that are exempt from obtaining a paper-certificated water right.  These private wells are also known as “exempt” wells.  Exempt wells typically withdraw small amounts of groundwater primarily for domestic use; also allowed are withdrawals for livestock watering and other limited purposes.  Exempt wells generally are not subject to adjudication, monitoring, or water use reporting requirements.  The Western States Water Council notes the concerns of some water right holders that the cumulative impact of exempt wells, especially in areas with limited water, could impair senior water rights (both surface water and groundwater), cause environmental problems, and threaten water supplies and quality.  These concerns have led, in some cases, to calls for restrictions and legal actions to repeal these exemptions.  Read more about domestic water well exemption.

Geologic Carbon Sequestration

The disposal of carbon dioxide (CO2) into the subsurface via well injection, also known as geologic carbon sequestration or carbon capture and storage (CCS), is one of a portfolio of technologies under consideration as a viable approach to mitigating greenhouse gas buildup.  Recognizing that this option for carbon capture holds great promise, it is important to understand it also has the potential to endanger underground sources of drinking water if proper safeguards are not taken.  Read more about geologic carbon sequestration.

Groundwater and Agriculture

Agriculture requires a steady supply of water to meet crop and livestock requirements, linking food security directly to water security.  Agriculture is the largest consumer of freshwater resources in the world.  Some countries do not have sufficient supplies of surface water to meet their agricultural demands, so groundwater is extracted to compensate for the difference.  In the United States, about 65% of groundwater withdrawals are for agricultural irrigation, which averages an estimated 50 billion gallons of water per day.  Read more about groundwater and agriculture.

Groundwater and Drinking Water

Safe and reliable drinking water is essential for economic vitality and public health.  Nearly every activity at some level in a community requires water for proper function — from homes, schools, and municipal services to commercial, industrial, and agricultural processes of production and waste treatment.  The use of groundwater as a safe source of water supply has enabled communities to exist in locations without access to streams, lakes, or reservoirs.  With increased population and economic activities that generate pollution, communities must be more vigilant in protecting their drinking water sources.  Read more about groundwater and drinking water.

Groundwater and Energy

While groundwater is indispensable for energy production, the reverse is also true, as energy is required for groundwater withdrawal, treatment, and delivery.  Groundwater and energy are, therefore, closely interconnected, so as the demand for energy increases, the demand for groundwater increases as well.  Similarly, energy conservation is directly linked to water conservation, which is necessary to ensure a lasting groundwater supply for future generations.  As the need for water continues to grow to meet the demands of a growing population, understanding the relationship between groundwater and energy will be essential for safeguarding continued delivery of energy and water to consumers.  Read more about groundwater and energy.

Energy use for water is a function of many variables, including water source.  The energy costs for groundwater include the cost to lift the groundwater to the surface.  Groundwater sources typically use about 30 percent more energy than do surface water supplies.  Read more about energy utilization for groundwater supply in the United States in this backgrounder document.

Lead Presence in Well Systems

Lead is a naturally occurring metal that does not alter the taste, odor, or color of water.  Due to the known health effects from lead exposure, the U.S. Environmental Protection Agency has set regulations intended to limit the amount of lead in drinking water.  Water distributed by public water systems is regulated via the Safe Drinking Water Act and the Lead and Copper Rule.  Read more about lead presence in well systems.

Managed Aquifer Recharge: A Water Supply Management Tool

Groundwater is a critical component of this nation’s water resources.  Approximately 78 percent of community water systems and nearly all rural water supplies use groundwater.  Groundwater is the source for 42 percent of the nation’s agricultural irrigation water.  Additionally, groundwater also feeds streams and rivers, especially during periods of drought or low flow, providing environmental benefits and sustaining ecosystem services.  Read more about managed aquifer recharge.

Water Wells in Proximity to Natural Gas or Oil Development

Hydraulic fracturing has captured headlines in areas where gas development is occurring.  Hydraulic fracturing is a petroleum-industry process in which fluids, commonly made up of water and a small percentage of chemical additives, are combined with sand and pumped at very high pressure into geologic formations holding gas.  The resulting fractures allows the release of natural gas, which can be collected.  NGWA has developed recommendations for testing well water before and after gas and oil production to monitor any changes in water quality related to hydraulic fracturing fluids.  Read more about water wells in proximity to natural gas or oil development.