Groundwater and Streamflow Information Program

Groundwater monitoring

National Groundwater Monitoring Network

National Groundwater Monitoring Network

Learn about the NGWMN and explore the multi-agency groundwater portal.

NGWMN Home Page

Next Generation Water Observing System

Next Generation Water Observing System

The NGWOS will provide quantitative info on streamflow, evapotranspiration, snowpack, soil moisture, water quality, groundwater / surface water connections, and water use.

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The USGS works in collaboration with partners to monitor groundwater levels using the framework of the National Groundwater Monitoring Network (NGWMN). This collaborative groundwater network of Federal, State, and local agency data providers was authorized by the SECURE Water Act in 2009 and aims to build and refine a national network of wells that meet specific criteria related to quality, accessibility, density, and frequency of measurement criteria. Within the NGWMN, the USGS provides Federal support for a Climate Response Network (CRN) outfitted with continuous, real-time instrumentation that is designed to serve as a measure of groundwater conditions during drought and provide long-term groundwater levels.


Below, please find several highlights of recent groundwater monitoring accomplishments:

  • In 2018, planning began for next-generation groundwater/surface-water interaction monitoring, which includes the use of small unmanned aircraft systems (drones) to delineate zones of groundwater discharge to streams on the basis of differences in groundwater and surface-water thermal properties.
  • In 2018 a total of 1,115 groundwater level sites were added to the NGWMN, bringing the number of long-term water-level sites monitored to over 7,000 wells. In addition, 584 new water-quality sites were added to NGWMN bringing the total number of sites to nearly 2,000. Four new data providers were added to the NGWMN bringing the total to 25. Sites are present in all 50 states and three U.S. Territories and in 62 of the 67 principal aquifers.
    • In August 2018, the number of water-level wells supplied by state and local agencies exceeded the number supplied by the USGS for the first time. This represents remarkable participation and enthusiasm among state agencies for the goals of the NGWMN. The number of state agency sites in the water-quality network have exceeded USGS sites since 2015.
    • In 2018, the Water Replenishment District of South California became the first local agency to be a data provider to the NGWMN. Participation in the NGWMN is open to local agencies including municipalities, counties, watershed organizations, and water-management districts
  • In 2018, 244 sites of the 370 national Climate Divisions were funded and presenting real-time data. This represents an increase of 10 wells in the network over 2017. 
  • In 2018, the Washington WSC began analyzing CRN records in the Northwest Region for a drought study. The project title is "Classification of Water Resources Vulnerability to Drought in the Pacific Northwest." One of the key objectives of the project is to examine and characterize groundwater-level variability in response to drought
  • Scientists are making strong cases for statistical trend analysis of groundwater levels to understand the effects of climate variability and other factors and thus supply valuable information to decision-makers. Dudley and Hodgkins (2013) and Hodgkins and others (2017) tested trends “using only the longest and most complete groundwater records;” many of the wells used in these studies were part of the CRN and NGWMN in New England and the glaciated regions of the Midwest. Wide areas of several states, including Minnesota, South Dakota, Iowa, Missouri, Illinois, Michigan, and Pennsylvania could not be analyzed because of scarcity of long-term records in those areas, reinforcing the need for comprehensive water-level monitoring to meet future freshwater requirements.
  • The Caribbean-Florida Water Science Center (CFWSC) maintains 13 wells in the CRN. In 2017, ten of the 13 CFWSC CRN-funded wells recorded period-of-record highs (average duration more than 27 years) in response to either Hurricane Irma or Hurricane Maria (3 in the USVI, 3 in PR, and 4 in Florida). Without the CRN funding, the effects on groundwater levels in these climate-response wells, particularly in PR and the USVI, would have gone unnoticed.
  • In accordance with P.L. 104-66, the USGS provided the latest biennial reports and associated water-level and water-level change maps for the High Plains aquifer (underlying Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming) to Congress.

Stakeholder Quotes

“The National Groundwater Monitoring Program has allowed NH Geological Survey to provide New Hampshire’s Drought Management team better support for decision making.”
Gregory Barker, New Hampshire Geological Survey

“NGWMN funding helps ensure that Maryland will have reliable and accurate groundwater-level monitoring into the foreseeable future.” 
Andrew Staley, Maryland Geological Survey, Department of Natural Resources