Dane County, Wisconsin: drinking water report. Dane County – Madison – serves about 570,000 residents.
Dane County – Madison – serves about 570,000 residents. Madison draws from 22 deep groundwater wells tapping the Mt. Simon and Wonewoc aquifer formations. Unlike most major cities, Madison relies 100% on groundwater, with no surface water intake. The aquifer system is deep and generally well-protected, producing water that requires minimal treatment.
Madison's groundwater supply is naturally clean, but the city sits on an isthmus between two lakes (Mendota and Monona), and urbanization has affected shallow groundwater quality. The deep wells draw from formations well below the zone of surface contamination, but emerging contaminants are being tracked.
UCMR5 data shows PFAS detections in some Madison Water Utility wells. Truax Field (Dane County Regional Airport), which hosts an Air National Guard base, is a confirmed PFAS source. According to the Wisconsin DNR's 2024 monitoring data, three wells in the Madison system showed PFAS above the state's recommended standards. Wisconsin has been developing enforceable PFAS standards, with proposed groundwater standards among the most protective in the Midwest.
Madison's groundwater supply is generally excellent, but PFAS near Truax Field and emerging contaminants are worth monitoring.
Check your water for data specific to your well zone. For PFAS, activated carbon or reverse osmosis provide household protection. Our water filter guide covers effective options. Pull your detailed report, and visit our Wisconsin page for statewide data.