Sauk County, Wisconsin: drinking water report. Sauk County in south-central Wisconsin has about 64,000 residents, with Baraboo as the county seat.
Sauk County in south-central Wisconsin has about 64,000 residents, with Baraboo as the county seat. The Badger Army Ammunition Plant – a 7,400-acre former munitions manufacturing facility – dominates the county's environmental story. Most communities rely on groundwater from sandstone and dolomite aquifers, and the county's mix of dairy farming and the military legacy creates overlapping contamination concerns.
The Badger Army Ammunition Plant operated from 1942 to 1975, producing propellants and explosives. According to the Wisconsin DNR's 2024 remediation status report, groundwater contamination from the facility includes carbon tetrachloride, dinitrotoluene, and perchlorate. Contaminant plumes extend beyond the facility boundary in multiple directions, and monitoring wells show carbon tetrachloride at 12 ppb – above the MCL of 5 ppb – in some off-site locations.
PFAS from the facility's fire training operations has been confirmed. A 2024 DNR investigation found PFOS at 25 ppt in monitoring wells at the site boundary. Agricultural nitrate from dairy operations in the surrounding area adds a third contamination source – 18% of private wells tested in Sauk County exceeded the nitrate MCL.
Sauk County's Badger Plant contamination is well-documented, and the plume boundaries are mapped. If you live downgradient from the facility, particularly in the Merrimac, Prairie du Sac, or Sauk Prairie areas, testing your private well for VOCs and PFAS is essential.
Check your water for available data. For the mix of military and agricultural contamination found in Sauk County, reverse osmosis provides the broadest household protection. Our water filter guide covers systems rated for munitions-related contaminants. Pull your detailed report for local data, and visit our Wisconsin page for statewide context.