Well water in Cottonwood County, Minnesota
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Testing recommended
tested well samples in Cottonwood County exceeded the EPA limit for nitrate (10 mg/L), based on public data from USGS Water Quality Portal.
The strongest signal is arsenic: 36% of 11 local samples were above the limit, too few samples to carry the headline but first on the test list below.
68 private wells tested 2008 to 2021 in state summaries; 357 test results across 15 contaminants from at least 52 wells, 1972 to 2025; nitrate has the most at 92. Data refreshed September 15, 2026.
Compiled by Nick at Well Water Nerd from public records. How these pages are built
What homeowner tests found
MDH new private well arsenic tests: private wells tested and reported to the state, 2008 to 2021. Shares are against the level the state applies to each contaminant, named in the last column; several are stricter than EPA.
| Contaminant | Above state level | Wells tested | Median | 95th pct | Highest | State level |
|---|---|---|---|---|---|---|
| Arsenic | 68 | 2.7 | 13.9 | 10 ug/L |
What individual samples found
Each row summarizes every public sample for that contaminant inside Cottonwood 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 |
|---|---|---|---|---|---|---|
| Arsenic 1979 to 2013 | 11 | 82% | 2.02 | 48.3 | 10 ug/L EPA limit | |
| Lead 1979 to 2013 | 11 | 82% | 0.11 | 76.9 | 15 ug/L EPA limit | |
| Nitrate 1972 to 2013 | 92 | 64% | 0.105 | 58.6 | 10 mg/L EPA limit | |
| Fluoride 1972 to 2013 | 46 | 96% | 0.26 | 0.7 | 4 mg/L EPA limit | |
| Copper 1979 to 2013 | 11 | 82% | 0.009 | 0.041 | 1.3 mg/L EPA limit | |
| Chloride 1972 to 2025 | no limit | 86 | 100% | 6.69 | 972 | 250 mg/L nuisance level |
| Sodium 1972 to 2013 | no limit | 47 | 100% | 12 | 555 | 20 mg/L health guideline |
| Iron 1972 to 2013 | no limit | 23 | 100% | 2459 | 8,890 | 300 ug/L nuisance level |
| Manganese 1972 to 2013 | no limit | 23 | 100% | 375 | 1,648 | 300 ug/L health guideline |
Sampled fewer than 10 times, too few to summarize: Radium (226 + 228) (2), Uranium (1), E. coli (1), PFOS (1), PFOA (1), Radon (1).
Over time
Share of samples above the limit by period. A cell needs ten samples to show; a comparison needs twenty in each period. Later periods sample fewer wells, and often the ones already known to have a problem.
| Contaminant | before 2000 | 2000s | 2010s | 2020s |
|---|---|---|---|---|
| Nitrate | 10%52 samples | 16%38 samples | n/a | n/a |
| Fluoride | 0%26 samples | 0%19 samples | n/a | n/a |
Nitrate above the limit in Cottonwood County rose from 10% of 52 samples before 2000 to 16% of 38 in the 2000s.
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 homeowners in Cottonwood County who sent a sample to the state lab, the health-based limits most often exceeded were arsenic (12% of 68 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.
What to test for in Cottonwood County
- 1Arsenic36% of 11 local samples were above the limit.
- 2Lead27% of 11 local samples were above the limit.
- 3Nitrate12% of 92 local samples were above the limit.
- 4Coliform bacteriaRecommended for every private well, every year.
- 5RadonMedian local reading is 263 pCi/L.
- 6ChlorideDetected in 100% of local samples.
- 7IronDetected in 100% of local samples.
- 8Volatile organic compounds (VOCs)72 leaking underground storage tank sites on record locally.
- 9Metals panel1 hazardous waste site on record locally.
Test your Cottonwood County well for arsenic, lead 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 Minnesota: certified labs, state programs and prices.
Already have results back? Get your lab report read against the Cottonwood County numbers, $29. Every line explained, ranked by what matters, with the fix for each.
Wells in Cottonwood County
439 domestic wells in Cottonwood County are on record with the state since 1950. 18% are drilled into bedrock, and the typical well is 152 feet deep (one in ten goes past 309 feet).
In a typical Cottonwood County well, bedrock starts about 95 feet down.
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 Minnesota Well Index and choose Water Well.
- The record shows depth, casing, depth to bedrock, aquifer, static water level and the driller; new wells since 2008 also show the arsenic test result.
Wells drilled since 1974 have records; older wells appear only if a later owner reported them.
The rock under Cottonwood 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 Minnesota
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.
- Wells and Borings, Minnesota Department of Health
- Accredited Laboratories as Well Partners, Minnesota Department of Health
Contamination sources on record in Cottonwood County
MPCA records 72 leaking underground storage tank sites and 1 hazardous waste site in Cottonwood County, among 199 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.
- 72
- leaking underground storage tank sitesGasoline and heating oil that leaked from tanks move through groundwater as benzene, MTBE and other volatile organic compounds.
- 1
- hazardous waste siteSolvents, degreasers and metals from industrial sites can travel far in fractured bedrock.
- 93
- registered underground storage tank sitesRegistered tanks are regulated and inspected; they matter most when they are old or near a shallow well.
- 22
- lined landfills and transfer facilities
- 11
- other remediation projects
Treatment that fits the local profile
Arsenic
Point-of-use reverse osmosis; Adsorptive media (iron-based) whole-house; Anion exchange
Lead
Point-of-use reverse osmosis; Certified lead-removal carbon filter; Neutralizing filter to raise pH and stop leaching
Nitrate
Point-of-use reverse osmosis; Anion exchange; Distillation
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
Some links below are affiliate links. If you buy through one, the merchant pays us a commission at no extra cost to you. It does not change which products we list or what the data says.
For arsenic
Under-sink reverse osmosis system
under-sink or countertop, about $300
Look for NSF/ANSI 58 certification listing the contaminant you need removed.
For arsenic
Whole-house arsenic and uranium filter
whole-house, at the point of entry, about $2,500
Adsorptive iron-based media; sized to your well yield.
For arsenic
Aquasana SmartFlow reverse osmosis
under-sink or countertop, about $225
Certified to NSF/ANSI 58 and 53 to reduce arsenic (96%, pentavalent), fluoride (90%), lead (99%), nitrate, nitrite and PFOA/PFOS at the kitchen tap, with a remineralizer.
For lead
Aquasana Claryum 3-Stage under-sink filter
under-sink or countertop, about $175
Certified to NSF/ANSI 53 to reduce 99% of lead and 99.7% of PFOA and PFOS at the tap. Not a fix for arsenic, nitrate or bacteria.
For lead
Acid neutralizing filter
whole-house, at the point of entry, about $1,200
Raises pH so plumbing stops leaching lead and copper.
For iron
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 Cottonwood County
No water treatment company serves Cottonwood 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 Cottonwood County, and you get an email naming it first.
Common questions
How deep are wells in Cottonwood County?
The typical domestic well in Cottonwood County is 152 feet deep, based on 439 wells reported to the state since 1950. One in ten is deeper than 309 feet. 18% are drilled into bedrock.
Is there arsenic in well water in Cottonwood County?
Arsenic was detected in 82% of 11 public well samples in Cottonwood County, and 36% 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 often should I test a private well in Cottonwood 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 Cottonwood County
24 towns have fewer than 30 public samples and are included in the Cottonwood County totals above rather than shown separately: Amboy township, Amo township, Ann township, Bingham Lake, Carson township, Comfrey, Dale township, Delton township, Germantown township, Highwater township, Jeffers, Lakeside township, Midway township, Mountain Lake, Mountain Lake township, Rose Hill township, Selma township, Southbrook township, Springfield township, Storden, Storden township, Westbrook, Westbrook township, Windom.
Counties near Cottonwood 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 Minnesota dataset as CSV, every county and town, with the sources named.
Sources
- USGS Water Quality Portal: 357 samples in Cottonwood 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.
- MDH new private well arsenic tests: summaries for 1 contaminants in Cottonwood County, up to 68 wells each. Arsenic results for every new private well drilled and tested August 2008 to December 2021, reported to the Minnesota Department of Health by well contractors and published by county. Mandatory test on new wells only, so older wells are not represented; 64,793 wells statewide. Shares are against 10 ug/L, which MDH applies as its advice level. Median and 95th percentile published per county. Retrieved September 15, 2026.
- Minnesota Well Index: 1,516 well records in Cottonwood County, 439 domestic. Well construction records from the Minnesota Well Index (Minnesota Department of Health), non-public-supply wells. Only aggregates are shown; owner names and addresses are never stored. Retrieved September 15, 2026.
- MPCA regulated sites: 199 regulated sites located in Cottonwood County. Tank, leak, remediation, Superfund and landfill sites from the Minnesota Pollution Control Agency What's In My Neighborhood database. Retrieved September 15, 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.