Well water in Vilas County, Wisconsin

In Vilas County, 8% of 175 private wells tested between 1993 and 2025 had total coliform above the Wisconsin limit (any detection), according to the UWSP Well Water Quality Viewer.

3,222 private wells tested 2000 to 2025 in state summaries; 8 individual samples from 8 wells, 1971 to 2013. 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 2025. 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	68	32%	10,731	300 ug/L
Manganese	78	10%	2,210	300 ug/L
Total coliform	175	8%
Sodium	65	3%	27.6	20 mg/L
Copper	78	3%	2.42	1.3 mg/L
Lead	78	3%	78	15 ug/L
Arsenic	265	2%	177	10 ug/L
Chloride	167	1%	790	250 mg/L
Nitrate	3,222	<1%	32	10 mg/L
E. coli	14	0%

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What this means

Among homeowners in Vilas County who sent a sample to the state lab, the health-based limits most often exceeded were total coliform (8% of 175 wells), copper (3% of 78 wells), and lead (3% of 78 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 manganese 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 Vilas County

Volatile organic compounds (VOCs)47 leaking underground storage tank sites on record locally.
Iron32% of 68 local wells tested were above the Wisconsin nuisance level.
Manganese10% of 78 local wells tested were above the Wisconsin enforcement standard.
Total coliform8% of 175 local wells tested were above the Wisconsin limit (any detection).
Sodium3% of 65 local wells tested were above the EPA advisory level.
Copper3% of 78 local wells tested were above the Wisconsin enforcement standard.
Lead3% of 78 local wells tested were above the Wisconsin enforcement standard.
Arsenic2% of 265 local wells tested were above the Wisconsin enforcement standard.
Chloride1% of 167 local wells tested were above the Wisconsin nuisance level.

Contamination sources on record in Vilas County

Wisconsin DNR records 47 leaking underground storage tank sites in Vilas County, among 266 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.

47: leaking underground storage tank sitesGasoline and heating oil that leaked from tanks move through groundwater as benzene, MTBE and other volatile organic compounds.
46: lined landfills and transfer facilities
173: 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
Iron: Oxidizing filter whole-house; Water softener (low levels); Aeration plus filtration
Manganese: Oxidizing filter (greensand, birm) whole-house; Water softener (low levels); Point-of-use reverse osmosis
Copper: Neutralizing filter to raise pH; Point-of-use reverse osmosis
Chloride: Point-of-use reverse osmosis; Distillation

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Common questions

Is there arsenic in well water in Vilas County?

Arsenic was detected in 100% of 8 public well samples in Vilas 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 Vilas County?

The median radon level across 5 public samples in Vilas County was 280 pCi/L, with a high of 640 pCi/L. New Hampshire recommends treatment above 2,000 pCi/L.

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

Arbor Vitae1% nitrate
Boulder Junction<1% nitrate
Cloverland<1% nitrate
Conover0% nitrate
Lac du Flambeau6% arsenic
Land O'Lakes0% nitrate
Lincoln1% nitrate
Manitowish Waters0% nitrate
Phelps0% nitrate
Plum Lake<1% nitrate
Presque Isle0% nitrate
St. Germain2% nitrate
Washington2% nitrate
Winchester1% nitrate

1 towns have fewer than 30 public samples and are included in the Vilas County totals above rather than shown separately: Eagle River.

Sources

USGS Water Quality Portal: 64 samples in Vilas 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 Vilas County, up to 3,222 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: 266 regulated sites located in Vilas 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.