Groundwater, Aquifers, Wells, and Springs

The age of groundwater is key in predicting which contaminants it might contain. There are many tracers and techniques that allow us to estimate the age—or mix of ages—of the groundwater we depend on as a drinking water supply.

Volatile organic compounds (VOCs) are chemicals that both vaporize into air and dissolve in water. VOCs are pervasive in daily life, because they’re used in industry, agriculture, transportation, and day-to-day activities around the home. Once released into groundwater, many VOCs are persistent and can migrate to drinking-water supply wells.

The redox state of groundwater—whether the groundwater is oxic (oxidized) or anoxic (reduced)—has profound implications for groundwater quality. Knowing the redox conditions of groundwater can help determine whether it contains elevated levels of many contaminants, including arsenic, nitrate, and even some manmade contaminants.

In 1991, Congress established the National Water-Quality Assessment (NAWQA) Project to address where, when, why, and how the Nation's water quality has changed, or is likely to change in the future, in response to human activities and natural factors. This page discusses the first two decadal cycles of NAWQA research from 1991 through 2012.

All water naturally contains dissolved solids that can make it "brackish" or distastefully salty. The amount of freshwater for drinking-water, agricultural, industrial, and environmental needs has declined in many areas and has led to concerns about future availability. The USGS conducted a national assessment of brackish aquifers that could supplement or replace freshwater sources.

The Harlem and Bronx Rivers provide ecological and social resources in an intensively urban area. Connecting people to rivers requires clean water—the USGS is helping to assess the efficacy of green infrastructure to improve the quality of stormwater that flows into the rivers.

The Valle de Oro National Wildlife Refuge, just 7 miles south of downtown Albuquerque on the Rio Grande, will reconnect people, especially young people, with nature in this highly populated area. The USGS is gathering data that will help gauge the success of habitat restoration efforts.

USGS National Water Quality Assessment (NAWQA) studies require analyses of stream and bed-sediment samples for major ions, nutrients, sediments, and organic contaminants that are consistent across time and space. Procedures have been designed specifically to produce information that is comparable among studies in different parts of the Nation.

USGS scientists are using high-resolution handheld and airborne thermal imaging cameras in groundwater/surface-water exchange studies and other investigations where surface temperature contrasts indicate various hydrological processes. These cameras are used to quickly locate and characterize thermal (temperature) anomalies along streams, lakes, wetlands, estuaries, and across the landscape...

USGS scientists are working alongside university researchers in Alaska to understand how groundwater and permafrost conditions change over time due to seasonal variations and climate change. Changes in permafrost can pose a threat to built infrastructure (like roads, homes, and pipelines) and to valued ecological resources that provide important habitats for wildlife.

Fiber-optic distributed temperature sensing (FO-DTS) technology can be used for characterizing estuary-aquifer and stream-aquifer interaction and for identifying transmissive fractures in bedrock boreholes.

Borehole nuclear magnetic resonance (NMR) is an emerging geophysical method being applied to hydrogeology investigations.