Well water in Ontonagon County, Michigan
No public well test results have been compiled for Ontonagon County yet. The USGS national arsenic model estimates that 7% of the 1,937 people on private wells there draw water with arsenic above 10 ug/L, the EPA limit, based on geology, well depth and land use rather than local tests.
The strongest signal is coliform bacteria: Recommended for every private well, every year, too few samples to carry the headline but first on the test list below.
90 test results across 11 contaminants from at least 6 wells, 1975 to 1990; nitrate has the most at 16. Data refreshed September 15, 2026.
Compiled by Nick at Well Water Nerd from public records. How these pages are built
An estimated 1,937 people in Ontonagon County get their drinking water from a private well, per USGS 2015 county water use. That is about 32% of residents.
Separately, the USGS national arsenic model estimates that 7% of the 1,937 people on private wells in Ontonagon County draw water above 10 ug/L (the model's range is 6% to 8%), from geology and well depth rather than local tests.
What individual samples found
Each row summarizes every public sample for that contaminant inside Ontonagon 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 | Above limit | Samples | Detected | Median | Highest | Limit |
|---|---|---|---|---|---|---|
| Nitrate 1975 to 1987 | 16 | 75% | 0.015 | 0.5 | 10 mg/L EPA limit |
Sampled fewer than 10 times, too few to summarize: Copper (9), Lead (9), Arsenic (8), Fluoride (8), Uranium (5), Manganese (9), Iron (9), Sodium (8), Chloride (8), Radon (1).
Closer than the county
See the sampled wells near your address
The same records, drawn around one point: which wells within a few miles were sampled and what they found, how deep the wells next to you were drilled, and any leaking tank or cleanup site within a mile.
Check my addressWhat this means
Among contaminants with a federal limit, no tested sample in Ontonagon County came back above it. That is reassuring, but sampling is uneven: wells that were never tested are not in this data.
Manganese, Iron, and Chloride are widespread in local groundwater. They are mainly a staining and taste problem, but high manganese also carries a health advisory for infants.
What to test for in Ontonagon County
- 1Coliform bacteriaRecommended for every private well, every year.
- 2RadonMedian local reading is 5.5 pCi/L.
- 3NitrateRecommended for every private well, especially near farms or septic systems.
- 4FluorideDetected in 100% of local samples.
- 5IronDetected in 100% of local samples.
- 6ChlorideDetected in 100% of local samples.
- 7CopperDetected in 89% of local samples.
- 8Volatile organic compounds (VOCs)11 leaking underground storage tank sites on record locally.
- 9Metals panel23 hazardous waste sites on record locally.
Test your Ontonagon County well for coliform bacteria, radon and nitrate
Certified lab analysis of your own tap water, bottles and prepaid return shipping included. The Essential well panel covers arsenic, uranium, nitrate, lead, copper, manganese, iron, sodium and bacteria; radon and PFAS are add-ons.
Order the Tap Score well water test kit, from $209Already tested? Upload the report
Just want bacteria checked first? Tap Score coliform and E. coli test, $99. Coliform and E. coli are the tests every well needs every year.
Want a quick look before paying for a lab? Home well water test strips on Amazon check hardness, iron, pH and nitrate in minutes. They are a screen, not a result: arsenic, bacteria, uranium and PFAS need a certified lab.
Affiliate links: the merchant pays us a commission and the price is the same for you. It does not change what the data above says. As an Amazon Associate we earn from qualifying purchases.
Where to get a well tested in Michigan: certified labs, state programs and prices.
Already have results back? Get your lab report read against the Ontonagon County numbers, $29. Every line explained, ranked by what matters, with the fix for each.
Wells in Ontonagon County
1,394 domestic wells in Ontonagon County are on record with the state since 1929. 67% are drilled into bedrock, and the typical well is 110 feet deep (one in ten goes past 240 feet).
In a typical Ontonagon County well, bedrock starts about 51 feet down, the median yield is 8 gallons per minute, 16% of wells yield under 3 gallons per minute and usually need a storage tank.
Bedrock wells are where arsenic, uranium and radon come from: the water sits in fractures in granite and metamorphic rock and picks up whatever the rock carries. That is why testing for those three matters more here than in a dug or gravel well.
Find your own well's report
The state keeps the driller's report for most wells drilled since 1984. It tells you how deep your well is, where bedrock starts, and how much water it makes, which decides what treatment can work.
- Open Wellogic (EGLE) and choose Water Well.
- The record lists depth, casing, static water level, the pump test and the geologic log.
Michigan has required well records since 1966, so most drilled wells are on file.
The rock under Ontonagon County
Not a principal aquifer
The USGS map places this area outside any principal aquifer, which usually means wells here draw from fractured bedrock or thin local deposits rather than a large regional aquifer. Bedrock wells of that kind are where arsenic, radon and uranium turn up, and yields vary from well to well.
Classification from the USGS Principal Aquifers of the United States (national map, 2003 edition, GIS release 2015), read at the county centroid. A single well can sit in a different unit, especially near a boundary.
Official help in Michigan
Two places to start that are not selling anything: the state program that answers private well questions, and its list of labs certified to run drinking water tests. A certified lab is the difference between a result you can act on and a number.
- Private Residential Water Well Testing, Michigan EGLE
- Laboratory certification program, Michigan EGLE
Contamination sources on record in Ontonagon County
Michigan EGLE records 11 leaking underground storage tank sites and 23 hazardous waste sites in Ontonagon County, among 76 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.
- 11
- leaking underground storage tank sitesGasoline and heating oil that leaked from tanks move through groundwater as benzene, MTBE and other volatile organic compounds.
- 23
- hazardous waste sitesSolvents, degreasers and metals from industrial sites can travel far in fractured bedrock.
- 40
- registered underground storage tank sitesRegistered tanks are regulated and inspected; they matter most when they are old or near a shallow well.
- 2
- lined landfills and transfer facilities
Treatment that fits the local profile
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
Systems we would look at first
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For manganese
Iron and manganese oxidizing filter
whole-house, at the point of entry, about $1,800
Air-injection or greensand media; fixes staining at the source.
Free, no obligation
Get on the list for a free in-home water test in Ontonagon County
No water treatment company serves Ontonagon County through Well Water Nerd yet. We are signing licensed companies on county by county: they test at your tap for free, walk you through the numbers, and quote treatment only if something needs fixing. Leave your details and you are first in line. Nothing is shared until a company joins for Ontonagon County, and you get an email naming it first.
Common questions
How deep are wells in Ontonagon County?
The typical domestic well in Ontonagon County is 110 feet deep, based on 1,394 wells reported to the state since 1929. One in ten is deeper than 240 feet. 67% are drilled into bedrock.
How often should I test a private well in Ontonagon 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 Ontonagon County
11 towns have fewer than 30 public samples and are included in the Ontonagon County totals above rather than shown separately: Bergland township, Bohemia township, Carp Lake township, Greenland township, Haight township, Interior township, Matchwood township, McMillan township, Ontonagon township, Rockland township, Stannard township.
Counties near Ontonagon County
Closest first. Groundwater does not stop at a line on a map, so the next county over is a fair second opinion.
Want the numbers themselves? Download the Michigan dataset as CSV, every county and town, with the sources named.
Sources
- USGS Water Quality Portal: 90 samples in Ontonagon 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.
- USGS national arsenic model (Ayotte 2017): estimated share of 1,937 people on private wells in Ontonagon County above 10 ug/L of arsenic, from geology, well depth and land use. County estimates of domestic well users with arsenic above 10 ug/L from the USGS national logistic regression model (Ayotte, Medalie and Qi, 2017), with private well population from the USGS 2015 county water-use compilation (Dieter and others, 2018). Retrieved September 15, 2026.
- Michigan Wellogic well records: 1,394 well records in Ontonagon County, 1,394 domestic. Water well records from Wellogic, the Michigan Department of Environment, Great Lakes, and Energy statewide well database. Only aggregates are shown; owner names and addresses are never stored. Retrieved September 16, 2026.
- Michigan EGLE regulated sites: 76 regulated sites located in Ontonagon County. Part 201 environmental contamination sites, underground storage tank facilities and Part 115 landfills from the Michigan Department of Environment, Great Lakes, and Energy. Retrieved September 16, 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.