Well water in Cohasset, Minnesota
In Cohasset, chloride was detected in 100% of 47 tested well samples from USGS Water Quality Portal.
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.
88 test results across 9 contaminants from at least 15 wells, 1965 to 2012; chloride has the most at 47. Data refreshed September 3, 2026.
Compiled by Nick at Well Water Nerd from public records. How these pages are built
What individual samples found
Each row summarizes every public sample for that contaminant inside Cohasset. 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 |
|---|---|---|---|---|---|---|
| Chloride 1965 to 2012 | no limit | 47 | 100% | 5.44 | 45.1 | 250 mg/L nuisance level |
Sampled fewer than 10 times, too few to summarize: Nitrate (7), Fluoride (5), Arsenic (4), Copper (4), Lead (4), Iron (7), Manganese (5), Sodium (5).
Closer than the town
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 Cohasset came back above it. That is reassuring, but sampling is uneven: wells that were never tested are not in this data.
Chloride, Iron, and Manganese 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 Cohasset
- 1Coliform bacteriaRecommended for every private well, every year.
- 2NitrateRecommended for every private well, especially near farms or septic systems.
- 3FluorideDetected in 100% of local samples.
- 4ChlorideDetected in 100% of local samples.
- 5IronDetected in 100% of local samples.
- 6ManganeseDetected in 80% of local samples.
- 7Volatile organic compounds (VOCs)15 leaking underground storage tank sites on record locally.
Test your Cohasset well for coliform bacteria, nitrate and fluoride
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 Cohasset numbers, $29. Every line explained, ranked by what matters, with the fix for each.
Wells in Cohasset
625 domestic wells in Cohasset are on record with the state since 1975. 9% are drilled into bedrock, and the typical well is 77 feet deep (one in ten goes past 177 feet).
In a typical Cohasset well, bedrock starts about 82 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 Cohasset
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 town 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 Cohasset
MPCA records 15 leaking underground storage tank sites in Cohasset, among 40 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.
- 15
- leaking underground storage tank sitesGasoline and heating oil that leaked from tanks move through groundwater as benzene, MTBE and other volatile organic compounds.
- 14
- registered underground storage tank sitesRegistered tanks are regulated and inspected; they matter most when they are old or near a shallow well.
- 10
- lined landfills and transfer facilities
- 1
- other remediation project
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
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 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 Cohasset
No water treatment company serves Cohasset 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 Cohasset, and you get an email naming it first.
Common questions
How deep are wells in Cohasset?
The typical domestic well in Cohasset is 77 feet deep, based on 625 wells reported to the state since 1975. One in ten is deeper than 177 feet. 9% are drilled into bedrock.
How often should I test a private well in Cohasset?
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 near Cohasset
Closest first. Groundwater does not stop at a line on a map, so the next town 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: 88 samples in Cohasset. Data from the Water Quality Portal, a service of USGS, EPA and USDA; groundwater samples collected by USGS and cooperators. Retrieved September 3, 2026.
- Minnesota Well Index: 749 well records in Cohasset, 625 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: 40 regulated sites located in Cohasset. 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.