Well water in Kewaunee County, Wisconsin
In Kewaunee County, 11% of 437 private wells tested between 2004 and 2025 had total coliform above the Wisconsin limit (any detection), according to the UWSP Well Water Quality Viewer.
887 private wells tested 2004 to 2024 in state summaries; 2 individual samples from 2 wells, 1959 to 1968. Data refreshed September 9, 2026.
What homeowner tests found
Wisconsin Well Water Quality Viewer samples: private wells tested and reported to the state, 2004 to 2024. Shares are against the level the state applies to each contaminant, named in the last column; several are stricter than EPA. County and state figures combine the town summaries, weighted by wells tested; medians are not combined.
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What this means
Among homeowners in Kewaunee County who sent a sample to the state lab, the health-based limits most often exceeded were total coliform (11% of 437 wells), E. coli (6% of 47 wells), and nitrate (6% of 887 wells). These are ordinary wells tested by their owners, so the shares are the best available picture of a typical well here, with one caveat: people test more often when they suspect a problem.
Iron and sodium exceed the state's advisory level in a sizable share of wells; these are mostly a taste, staining or diet issue rather than a toxicity one.
What to test for in Kewaunee County
- Volatile organic compounds (VOCs)59 leaking underground storage tank sites on record locally.
- Iron36% of 45 local wells tested were above the Wisconsin nuisance level.
- Sodium13% of 45 local wells tested were above the EPA advisory level.
- Total coliform11% of 437 local wells tested were above the Wisconsin limit (any detection).
- E. coli6% of 47 local wells tested were above the Wisconsin limit (any detection).
- Nitrate6% of 887 local wells tested were above the Wisconsin enforcement standard.
- Copper3% of 58 local wells tested were above the Wisconsin enforcement standard.
- Arsenic3% of 150 local wells tested were above the Wisconsin enforcement standard.
- Lead2% of 58 local wells tested were above the Wisconsin enforcement standard.
Contamination sources on record in Kewaunee County
Wisconsin DNR records 59 leaking underground storage tank sites in Kewaunee County, among 175 regulated sites in total. Groundwater does not follow property lines, so a well within a few hundred feet of one of these is worth testing for what that site could release.
- 59
- leaking underground storage tank sitesGasoline and heating oil that leaked from tanks move through groundwater as benzene, MTBE and other volatile organic compounds.
- 25
- lined landfills and transfer facilities
- 91
- other remediation projects
Treatment that fits the local profile
- Total coliform
- Inspect and repair the well cap and casing, then shock chlorinate and retest; UV disinfection whole-house; Chlorination system
- E. coli
- Shock chlorination and fix the well cap or casing; UV disinfection whole-house; Chlorination system
- Nitrate
- Point-of-use reverse osmosis; Anion exchange; Distillation
- Iron
- Oxidizing filter whole-house; Water softener (low levels); Aeration plus filtration
- Sodium
- Point-of-use reverse osmosis; Distillation
- Fluoride
- Point-of-use reverse osmosis; Activated alumina; Distillation
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Common questions
How often should I test a private well in Kewaunee County?
Test for bacteria and nitrate every year. Test once for arsenic, uranium, radon, fluoride, manganese and PFAS, then again every three to five years or after any change in taste, color, or plumbing.
Towns in Kewaunee County
- Ahnapee2% nitrate
- Carlton0% nitrate
- Casco9% nitrate
- Casco village21% nitrate
- Franklin9% total coliform
- Lincoln13% total coliform
- Luxemburg9% nitrate
- Montpelier8% nitrate
- Pierce0% nitrate
- Red River27% total coliform
- West Kewaunee3% total coliform
3 towns have fewer than 30 public samples and are included in the Kewaunee County totals above rather than shown separately: Algoma, Kewaunee, Luxemburg village.
Sources
- USGS Water Quality Portal: 4 samples in Kewaunee County. Data from the Water Quality Portal, a service of USGS, EPA and USDA; groundwater samples collected by USGS and cooperators. Retrieved September 3, 2026.
- Wisconsin Well Water Quality Viewer samples: summaries for 10 contaminants in Kewaunee County, up to 887 wells each. Private well samples compiled by the UWSP Center for Watershed Science and Education from the DNR Groundwater Retrieval Network, DATCP surveys, the UWSP Water and Environmental Analysis Lab and county health programs, published in the Wisconsin Well Water Quality Viewer with Wisconsin DHS. Samples are located to the town, village or city they fall in; one result per well and parameter (the latest) so repeat samples do not double count; wells without a state well number are keyed by location. Shares are against Wisconsin NR 140 enforcement standards (arsenic 10 ug/L, nitrate 10 mg/L as N, manganese 300 ug/L, lead 15 ug/L, copper 1.3 mg/L) and the iron and chloride secondary levels. Many samples were submitted by homeowners with a reason to test, so shares can run above a random survey. Retrieved September 9, 2026.
- Wisconsin DNR regulated sites: 175 regulated sites located in Kewaunee County. Open and closed remediation activities (BRRTS, including leaking underground storage tanks and spills) and landfill and waste sites from the Wisconsin Department of Natural Resources. Retrieved September 9, 2026.
Non-detects count as samples and are treated as zero when computing medians. Exactly at the limit counts as not above it. A sample belongs to the town containing the well's reported coordinates.