National Water Census: Groundwater

Science Center Objects

The National Water Census (NWC) is leveraging a long history of groundwater studies and is accelerating ongoing regional studies to assess the Nation's groundwater reserves, studies that formerly were conducted under the USGS Groundwater Resources Program. The NWC is also increasing the ability to integrate groundwater and surface-water analyses into watershed-level assessments of water availability.

Water Census  •  Streamflow  •  Groundwater  •  Water Use  •  Environmental Flows  •  Evapotranspiration  •  Focus Area Studies


Regional Groundwater Availability Studies

National Water Census: Regional Groundwater Availability Studies map

Map of Regional Groundwater Availability Studies from the USGS National Water Census.

A major element of the National Water Census is regional analysis of groundwater availability, continuing a series of studies begun under the USGS Groundwater Resources Program. Current plans call for studies of 30–40 principal aquifers that collectively account for more than 90 percent of the Nation's total groundwater withdrawals. The regional scale of these studies enables information to be integrated and consistent, so the resource can be analyzed and understood on an aquifer–wide scale. Therefore, it provides decision–makers with a better understanding of the status and trends in the Nation's groundwater availability. Water managers are now looking for ways to better manage known groundwater resources while also identifying supplemental sources of water. These multidisciplinary studies of regional groundwater availability across the United States will provide resource managers and policy makers with essential information needed for management of a limited resource.

View the list of regional groundwater availability studies

Groundwater Recharge, Storage, and Discharge Rates for Water Budgets

The National Water Census also will develop estimates of groundwater recharge, storage, and discharge at the watershed scale, as much as possible. These estimates will be made using a combination of information from large–scale studies, observed data on groundwater levels collected in well networks, analysis of streamflow records, water use, and other available information.

Brackish Water Sources

USGS WAUSP Water Census: Map of National Brackish Groundwater Assessment

Predicted depth to brackish groundwater from Brackish groundwater In the United States 

Brackish groundwater, as a resource for direct use or for desalination, potentially represents an increasingly important component of the Nation's water supply. Relatively little is known, however, about brackish groundwater as compared to fresh groundwater. A better understanding of the distribution and characteristics of brackish groundwater can provide information for future development of this resource. To satisfy requirements of the SECURE Water Act, the National Water Census provided funding to conduct the National Brackish Groundwater Assessment.

Read more about the National Brackish Groundwater Assessment.