Well water in Wood County, Wisconsin

In Wood County, 9% of 222 private wells tested between 1995 and 2025 had total coliform above the Wisconsin limit (any detection), according to the UWSP Well Water Quality Viewer.

2,180 private wells tested 2011 to 2025 in state summaries; 5 individual samples from 5 wells, 1966 to 1986. Data refreshed September 9, 2026.

What homeowner tests found

Wisconsin Well Water Quality Viewer samples: private wells tested and reported to the state, 2011 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	38	26%	5,837	300 ug/L
Sodium	39	18%	256	20 mg/L
Total coliform	222	9%
Manganese	53	9%	5,171	300 ug/L
Nitrate	2,180	5%	69	10 mg/L
Lead	67	3%	30	15 ug/L
Arsenic	110	3%	40	10 ug/L
Copper	54	2%	2.08	1.3 mg/L
Chloride	211	1%	838	250 mg/L
E. coli	20	0%

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What this means

Among homeowners in Wood County who sent a sample to the state lab, the health-based limits most often exceeded were total coliform (9% of 222 wells), nitrate (5% of 2,180 wells), and lead (3% of 67 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 Wood County

Volatile organic compounds (VOCs)160 leaking underground storage tank sites on record locally.
Iron26% of 38 local wells tested were above the Wisconsin nuisance level.
Sodium18% of 39 local wells tested were above the EPA advisory level.
Total coliform9% of 222 local wells tested were above the Wisconsin limit (any detection).
Manganese9% of 53 local wells tested were above the Wisconsin enforcement standard.
Nitrate5% of 2,180 local wells tested were above the Wisconsin enforcement standard.
Lead3% of 67 local wells tested were above the Wisconsin enforcement standard.
Arsenic3% of 110 local wells tested were above the Wisconsin enforcement standard.
Copper2% of 54 local wells tested were above the Wisconsin enforcement standard.

Contamination sources on record in Wood County

Wisconsin DNR records 160 leaking underground storage tank sites in Wood County, among 576 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.

160: leaking underground storage tank sitesGasoline and heating oil that leaked from tanks move through groundwater as benzene, MTBE and other volatile organic compounds.
55: lined landfills and transfer facilities
361: 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
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
Manganese: Oxidizing filter (greensand, birm) whole-house; Water softener (low levels); Point-of-use reverse osmosis
Fluoride: Point-of-use reverse osmosis; Activated alumina; Distillation

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Common questions

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

Arpin0% nitrate
Auburndale4% nitrate
Dexter0% nitrate
Grand Rapids13% total coliform
Hansen2% nitrate
Hewitt village3% nitrate
Lincoln10% nitrate
Marshfield6% nitrate
Milladore14% nitrate
Port Edwards23% nitrate
Port Edwards village0% nitrate
Richfield3% nitrate
Rudolph5% nitrate
Saratoga6% total coliform
Seneca4% nitrate
Sherry3% nitrate
Sigel0% nitrate
Wisconsin Rapids0% nitrate
Wood5% nitrate

15 towns have fewer than 30 public samples and are included in the Wood County totals above rather than shown separately: Arpin village, Auburndale village, Biron village, Cameron, Cary, Cranmoor, Hiles, Marshfield, Milladore village, Nekoosa, Pittsville, Remington, Rock, Rudolph village, Vesper village.

Sources

USGS Water Quality Portal: 12 samples in Wood 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 Wood County, up to 2,180 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: 576 regulated sites located in Wood 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.