Well water in Douglas County, Wisconsin
In Douglas County, 9% of 163 private wells tested between 2018 and 2025 had total coliform above the Wisconsin limit (any detection), according to the UWSP Well Water Quality Viewer.
1,000 private wells tested 2018 to 2025 in state summaries; 18 individual samples from 15 wells, 1970 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, 2018 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.
What individual samples found
Each row summarizes every public sample for that contaminant inside Douglas 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.
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What this means
Among homeowners in Douglas County who sent a sample to the state lab, the health-based limits most often exceeded were total coliform (9% of 163 wells) and lead (4% of 161 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.
Sodium and iron 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 Douglas County
- Volatile organic compounds (VOCs)289 leaking underground storage tank sites on record locally.
- Sodium35% of 122 local wells tested were above the EPA advisory level.
- Iron16% of 122 local wells tested were above the Wisconsin nuisance level.
- Total coliform9% of 163 local wells tested were above the Wisconsin limit (any detection).
- Lead4% of 161 local wells tested were above the Wisconsin enforcement standard.
- Manganese3% of 161 local wells tested were above the Wisconsin enforcement standard.
- Chloride3% of 164 local wells tested were above the Wisconsin nuisance level.
- Coliform bacteriaRecommended for every private well, every year.
- NitrateRecommended for every private well, especially near farms or septic systems.
Contamination sources on record in Douglas County
Wisconsin DNR records 289 leaking underground storage tank sites in Douglas County, among 657 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.
- 289
- leaking underground storage tank sitesGasoline and heating oil that leaked from tanks move through groundwater as benzene, MTBE and other volatile organic compounds.
- 56
- lined landfills and transfer facilities
- 312
- 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
- Sodium
- Point-of-use reverse osmosis; Distillation
- Iron
- Oxidizing filter whole-house; Water softener (low levels); Aeration plus filtration
- Chloride
- Point-of-use reverse osmosis; Distillation
- Manganese
- Oxidizing filter (greensand, birm) whole-house; Water softener (low levels); Point-of-use reverse osmosis
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Common questions
How often should I test a private well in Douglas 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 Douglas County
- Amnicon0% nitrate
- Bennett0% nitrate
- Brule0% nitrate
- Gordon0% nitrate
- Highland0% nitrate
- Lake Nebagamon village0% nitrate
- Oakland0% nitrate
- Solon Springs0% nitrate
- Solon Springs village0% nitrate
- Summit0% nitrate
- Superior0% nitrate
- Wascott0% nitrate
10 towns have fewer than 30 public samples and are included in the Douglas County totals above rather than shown separately: Cloverland, Dairyland, Hawthorne, Lakeside, Maple, Oliver village, Parkland, Poplar village, Superior, Superior village.
Sources
- USGS Water Quality Portal: 72 samples in Douglas 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 Douglas County, up to 1,000 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: 657 regulated sites located in Douglas 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.