Groundwater-Level Monitoring Network

Two men with a drill rig installing a groundwater monitoring well.
Installing a new monitoring well. (Photo by Jeff Miller, UW–Madison, University Communications.)

WGNHS and the U.S. Geological Survey (USGS) Upper Midwest Water Science Center have collaborated for decades to operate, maintain, and manage the Wisconsin Groundwater-Level Monitoring Network (WGLMN). This network consists of roughly 100 long-term monitoring wells, plus dozens of project-funded wells that are monitored for specific groundwater studies. Wisconsin’s long-term network wells are also part of the USGS’ National Groundwater Monitoring Network (NGWMN) and therefore bolster groundwater-level monitoring efforts across the country.

About the Network

The WGLMN dates back to 1946, when the Wisconsin State Legislature requested that WGNHS and the USGS Upper Midwest Water Science Center formally establish a groundwater-monitoring network. In recent decades, the Wisconsin Department of Natural Resources (WDNR) has become more involved and today serves as a critical partner in supporting the ongoing operation, maintenance, and management of the network.

Since 2015, multiple grants from the NGWMN program injected over $720,000 in new funding to repair and evaluate old wells, replace failing wells, and drill new wells in areas of the state lacking monitoring coverage. By 2024, these investments will have resulted in repairs and evaluations to 41 monitoring wells and the drilling of 21 new wells across 32 of Wisconsin’s 72 counties. Learn more about the highlights for NGWMN grants awarded to WGNHS in 20162018, and 2020.

The WGLMN’s long-term network provides a consistent, high-quality record of water-level fluctuations in both shallow and deep aquifers systems across the state. Water levels collected from the WGLMN help scientists and managers evaluate the effects of well pumping, the response of groundwater levels to drought or increased precipitation, and the effects of land-use change as well as climate change on groundwater resources. These data are also routinely used in the development of regional groundwater flow models because long-term water-level measurements serve as reliable calibration targets.

Video produced by Wisconsin Sea Grant.

Network data

Following the decommissioning of Groundwater Watch in September 2022, we recommend visiting the WDNR Water Quantity Data Viewer, the USGS NGWMN Data Portal, or the USGS National Water Information System (NWIS) Web Interface to search for and retrieve water-level data for wells in the Wisconsin Groundwater-Level Monitoring Network. For assistance or questions, please contact Pete Chase (; (608) 265-6003).

WDNR Water Quantity Data Viewer

USGS NGWMN Data Portal

USGS NWIS Web Interface

Monitoring a well

Following the installation of a new well, a detailed well-construction report is generated and a representative set of drill cuttings is transported to WGNHS’s Core Repository in Mount Horeb, Wisconsin. WGNHS then uses borehole video imaging and geophysical methods to record data about the well’s geologic characteristics while the USGS establishes an elevation datum and deploys water-level monitoring equipment—making the well fully operational for generations to come.

The photos below were taken at a monitoring well installation at Havenwoods State Forest in Milwaukee County. (Photos by Sara Stathas for the University of Wisconsin Water Resources Institute, used here with permission.)

A drilling rig in the foreground drills a well as three men watch from the background
Drilling a new monitoring well borehole using mud rotary. (Photo by Sara Stathas, University of Wisconsin Water Resources Institute)
A length of PVC pipe with parallel rows of perforations on its sides and a pointed cap on the end.
PVC well screen, prior to installation in the borehole. (Photo by Sara Stathas, University of Wisconsin Water Resources Institute)
Closer look at a mud rotary drill in action, with a sieve held to catch some of the mud
Drill cuttings collected with a mesh sieve to record the geology. (Photo by Sara Stathas, University of Wisconsin Water Resources Institute)
A plastic bin with about a dozen small clear baggies of geologic samples
Drill-cutting samples, collected at discrete depths. (Photo by Sara Stathas, University of Wisconsin Water Resources Institute)