Well Water Near the Former Badger Army Ammunition Plant, Sauk County

What the site was, and what it left behind

The Badger Army Ammunition Plant operated on roughly 7,400 acres near Baraboo (spanning parts of the Towns of Sumpter, Merrimac, and Prairie du Sac) from World War II through the Cold War era, manufacturing propellants and explosives. Decades of production left contaminated soil and groundwater across the site, with four primary plumes of polluted groundwater identified as moving southeast toward the Wisconsin River, according to Citizens for Safe Water Around Badger (CSWAB), the advocacy organization that has tracked this issue for decades. Contaminants documented at the site include carbon tetrachloride, trichloroethylene, and dinitrotoluenes (DNT) -- all carcinogens under Wisconsin's groundwater-quality standards -- along with nitroglycerin and other energetic compounds tied to the plant's original munitions production.

Testing has found extreme concentrations at points on the site: in September 2020, total DNT concentrations as high as roughly 1,287 micrograms per liter were reported -- about 25,000 times the state's groundwater enforcement standard of 0.05 micrograms per liter for total DNT, per CSWAB's reporting on state and Army testing data. A 2023 U.S. Geological Survey study modeled groundwater flow at the site in more technical detail, corroborating that contamination is actively moving rather than static.

An active, unresolved dispute -- not a closed cleanup

This is not a historical issue with a settled resolution. Per CSWAB's account of correspondence between the agencies, the U.S. Army Environmental Command has told the Wisconsin DNR it will not comply with the state's enforceable groundwater standards for certain of these cancer-causing chemicals, and the WDNR sent formal compliance-demand letters to the Army in June 2023, October 2023, and again in October 2024 without full resolution. Estimated cleanup costs for the site are reported to exceed $250 million, and a proposed treatment approach -- injecting emulsified vegetable oil into the groundwater to promote natural contaminant breakdown -- was slated for a roughly two-year pilot test before any broader rollout, as of this research pass.

Contamination has moved beyond the site's own boundary and, per CSWAB, now threatens as many as 300 rural residential drinking-water wells in the surrounding area. The Army has historically tested residential wells near the site and provided bottled water or a new well to affected households when contamination is detected -- but CSWAB has also reported the Army scaling back this testing in places, including dropping roughly 18 residential wells along the southwestern arm of Weigand's Bay from regular monitoring near the Deterrent Burning Ground area. If you're relying on Army-provided well monitoring as your only source of water-quality information near this site, that coverage may not be as complete or as current as you'd assume.

The site's current ownership: DNR recreation land, Ho-Chunk trust land, and USDA research land

The former plant's land is no longer a single military-controlled parcel. Roughly 3,900 acres transferred to the Wisconsin DNR as the Sauk Prairie Recreation Area (hiking, biking, hunting, and similar public recreational uses), while the remainder was divided primarily between the Ho-Chunk Nation (which took roughly 1,553 acres into federal trust under the FY2015 National Defense Authorization Act, with reported plans that may eventually include bison grazing) and the USDA's Dairy Forage Research Center (agricultural research). Groundwater contamination doesn't respect these newer property boundaries, so proximity to any of the three current owners' land -- not just the historic plant footprint on an old map -- is what matters for a nearby private well.

What to actually check before buying near this site

1. Ask Sauk County Environmental Health and the Wisconsin DNR directly whether a specific parcel falls within or near any of the site's known contamination plumes, rather than relying on distance from the old plant fence line alone.
2. If the parcel already has a private well, get an independent, current water test for the specific contaminants documented at this site (DNT and related energetic compounds, carbon tetrachloride, trichloroethylene) rather than a generic bacteria/nitrate test alone.
3. If the property is or was part of the Army's residential well-monitoring program, confirm directly whether it's still actively being tested -- monitoring scope has reportedly been reduced in at least one area.
4. For a new well on undeveloped land near the site, ask a Wisconsin-licensed well driller and Sauk County directly whether NR 812 siting requirements interact with any known contamination in the specific area, before drilling.
5. Don't assume the Army's cleanup timeline resolves the issue on any predictable schedule -- as of this research pass, the Army was in active non-compliance with state groundwater standards, with a cleanup cost estimate exceeding $250 million and no firm completion date identified.