Well water in Shawano County, Wisconsin

In Shawano County, 12% of 354 private wells tested between 1993 and 2025 had arsenic above the Wisconsin enforcement standard (10 ug/L), according to the UWSP Well Water Quality Viewer.

1,251 private wells tested 2000 to 2024 in state summaries; 32 individual samples from 15 wells, 1976 to 2024. Data refreshed September 9, 2026.

What homeowner tests found

Wisconsin Well Water Quality Viewer samples: private wells tested and reported to the state, 2000 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.

Contaminant	Wells tested	Above state level	Highest	State level
Iron	32	28%	14,000	300 ug/L
Sodium	33	21%	147	20 mg/L
Arsenic	354	12%	2,200	10 ug/L
E. coli	11	9%
Total coliform	131	8%
Nitrate	1,251	6%	31.2	10 mg/L
Manganese	45	4%	909	300 ug/L
Chloride	119	0%	158	250 mg/L
Lead	44	0%	14	15 ug/L
Copper	44	0%	0.863	1.3 mg/L

What individual samples found

Each row summarizes every public sample for that contaminant inside Shawano County. Above limit means above the EPA maximum contaminant level; where EPA has no enforceable limit, the row shows a health guideline or nuisance level instead.

Contaminant	Samples	Detected	Above limit	Median	Highest	Limit
Uranium 1994 to 2024	32	97%	3%	1.45	41.9	30 ug/L EPA limit
Radium (226 + 228) 2003 to 2015	18	83%	0%	0.245	0.5	5 pCi/L EPA limit
Radon 1993 to 2003	11	100%	no limit	920	22,000	2,000 pCi/L health guideline

Sampled fewer than 10 times, too few to summarize: Lead (4), Nitrate (4), Arsenic (5), Copper (2), Chloride (2), Manganese (1), Sodium (1).

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What this means

Among homeowners in Shawano County who sent a sample to the state lab, the health-based limits most often exceeded were arsenic (12% of 354 wells), E. coli (9% of 11 wells), and total coliform (8% of 131 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 Shawano County

Volatile organic compounds (VOCs)97 leaking underground storage tank sites on record locally.
Iron28% of 32 local wells tested were above the Wisconsin nuisance level.
Sodium21% of 33 local wells tested were above the EPA advisory level.
Arsenic12% of 354 local wells tested were above the Wisconsin enforcement standard.
E. coli9% of 11 local wells tested were above the Wisconsin limit (any detection).
Total coliform8% of 131 local wells tested were above the Wisconsin limit (any detection).
Nitrate6% of 1,251 local wells tested were above the Wisconsin enforcement standard.
Manganese4% of 45 local wells tested were above the Wisconsin enforcement standard.
Uranium3% of 32 local samples were above the limit.

Contamination sources on record in Shawano County

Wisconsin DNR records 97 leaking underground storage tank sites in Shawano County, among 332 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.

97: leaking underground storage tank sitesGasoline and heating oil that leaked from tanks move through groundwater as benzene, MTBE and other volatile organic compounds.
43: lined landfills and transfer facilities
192: other remediation projects

Treatment that fits the local profile

Arsenic: Point-of-use reverse osmosis; Adsorptive media (iron-based) whole-house; Anion exchange
E. coli: Shock chlorination and fix the well cap or casing; UV disinfection whole-house; Chlorination system
Total coliform: Inspect and repair the well cap and casing, then shock chlorinate and retest; 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
Uranium: Point-of-use reverse osmosis; Anion exchange; Whole-house anion exchange

Get your Shawano County water tested at home

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Common questions

Is there arsenic in well water in Shawano County?

Arsenic was detected in 40% of 5 public well samples in Shawano County, and 0% were above the EPA limit of 10 ug/L. Arsenic has no taste or smell; a lab test is the only way to know your level.

How high is radon in well water in Shawano County?

The median radon level across 11 public samples in Shawano County was 920 pCi/L, with a high of 22,000 pCi/L. New Hampshire recommends treatment above 2,000 pCi/L.

How often should I test a private well in Shawano 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 Shawano County

Almon25% nitrate
Angelica24% arsenic
Belle Plaine6% nitrate
Green Valley11% nitrate
Hartland6% nitrate
Lessor3% nitrate
Maple Grove0% nitrate
Pella6% nitrate
Red Springs0% nitrate
Richmond14% nitrate
Seneca5% nitrate
Washington8% nitrate
Waukechon0% nitrate
Wescott2% nitrate
Wittenberg6% nitrate

23 towns have fewer than 30 public samples and are included in the Shawano County totals above rather than shown separately: Aniwa, Aniwa village, Bartelme, Birnamwood, Birnamwood village, Bonduel village, Bowler village, Cecil village, Eland village, Fairbanks, Germania, Grant, Gresham village, Herman, Hutchins, Marion, Mattoon village, Morris, Navarino, Pulaski village, Shawano, Tigerton village, Wittenberg village.

Sources

USGS Water Quality Portal: 80 samples in Shawano 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 Shawano County, up to 1,251 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: 332 regulated sites located in Shawano 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.