Well water in Chisago County, Minnesota

In Chisago County, 4% of 1,261 private wells tested between 2008 and 2021 had arsenic above the EPA limit (10 ug/L), according to the Minnesota Department of Health.

1,261 private wells tested 2008 to 2021 in state summaries; 1,124 test results across 14 contaminants from at least 114 wells, 1967 to 2025; chloride has the most at 192. Data refreshed September 15, 2026.

Compiled by Nick at Well Water Nerd from public records. How these pages are built

An estimated 27,563 people in Chisago County get their drinking water from a private well, per USGS 2015 county water use. That is about 51% of residents.

Separately, the USGS national arsenic model estimates that 5% of the 27,563 people on private wells in Chisago County draw water above 10 ug/L (the model's range is 4% to 6%), from geology and well depth rather than local tests.

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	4%	1,261	2	8.8		10 ug/L

What individual samples found

Each row summarizes every public sample for that contaminant inside Chisago 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 1978 to 2025	5%	113	32%	0	25.8	10 ug/L EPA limit
Lead 1978 to 2025	3%	113	8%	0	200	15 ug/L EPA limit
Nitrate 1967 to 2011	2%	137	70%	0.009	13	10 mg/L EPA limit
Fluoride 1967 to 2025	0%	119	92%	0.179	0.56	4 mg/L EPA limit
Copper 1978 to 2025	0%	113	26%	0	0.128	1.3 mg/L EPA limit
Chloride 1967 to 2025	no limit	192	100%	5.83	595	250 mg/L nuisance level
Iron 1967 to 2025	no limit	140	93%	54.6	6847	300 ug/L nuisance level
Sodium 1967 to 2025	no limit	135	100%	5.33	35	20 mg/L health guideline
Manganese 1967 to 2025	no limit	48	100%	96.4	949	300 ug/L health guideline

Sampled fewer than 10 times, too few to summarize: Radium (226 + 228) (2), PFOA (6), PFOS (4), Uranium (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	7%46 samples	n/a	0%87 samples	n/a
Fluoride	0%26 samples	n/a	0%88 samples	n/a
Arsenic	27%15 samples	n/a	2%92 samples	n/a
Lead	20%15 samples	n/a	0%92 samples	n/a
Copper	0%15 samples	n/a	0%92 samples	n/a

Nitrate above the limit in Chisago County fell from 7% of 46 samples before 2000 to 0% of 87 in the 2010s.

Fluoride has held within a few points between the two most recent periods with enough samples.

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 address

What this means

Among homeowners in Chisago County who sent a sample to the state lab, the health-based limits most often exceeded were arsenic (4% of 1,261 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 Chisago County

1
Arsenic
5% of 113 local samples were above the limit.
2
Lead
3% of 113 local samples were above the limit.
3
Nitrate
2% of 137 local samples were above the limit.
4
Coliform bacteria
Recommended for every private well, every year.
5
Radon
Median local reading is 420 pCi/L.
6
Radium (226 + 228)
Above the limit in 2 of 2 local samples; too few to quote a rate.
7
Chloride
Detected in 100% of local samples.
8
Volatile organic compounds (VOCs)
125 leaking underground storage tank sites on record locally.
9
Metals panel
4 hazardous waste sites on record locally.

Test your Chisago 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 $209 Already 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 Chisago County numbers, $29. Every line explained, ranked by what matters, with the fix for each.

Wells in Chisago County

7,676 domestic wells in Chisago County are on record with the state since 1941. 19% are drilled into bedrock, and the typical well is 131 feet deep (one in ten goes past 232 feet).

In a typical Chisago County well, bedrock starts about 145 feet down.

1960s

313

1970s

1,188

1980s

3,697

1990s

2,282

2000s

162

2010s

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 Chisago County

Cambrian-Ordovician aquifer system

Sandstone. Sandstone wells draw from pore space in the rock and tend to be dependable. Iron, manganese and hardness are common, and some sandstones carry arsenic or radium, so a first test should include both.

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 Chisago County

MPCA records 125 leaking underground storage tank sites and 4 hazardous waste sites in Chisago County, among 301 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.

125: leaking underground storage tank sitesGasoline and heating oil that leaked from tanks move through groundwater as benzene, MTBE and other volatile organic compounds.
4: hazardous waste sitesSolvents, degreasers and metals from industrial sites can travel far in fractured bedrock.
110: registered underground storage tank sitesRegistered tanks are regulated and inspected; they matter most when they are old or near a shallow well.
33: lined landfills and transfer facilities
29: 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 Chisago County

No water treatment company serves Chisago 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 Chisago County, and you get an email naming it first.

Common questions

How deep are wells in Chisago County?

The typical domestic well in Chisago County is 131 feet deep, based on 7,676 wells reported to the state since 1941. One in ten is deeper than 232 feet. 19% are drilled into bedrock.

Is there arsenic in well water in Chisago County?

Arsenic was detected in 32% of 113 public well samples in Chisago County, and 5% 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 Chisago 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 Chisago County

15 towns have fewer than 30 public samples and are included in the Chisago County totals above rather than shown separately: Center City, Chisago City, Chisago Lake township, Fish Lake township, Franconia township, Harris, Lindstrom, Nessel township, North Branch, Rush City, Rushseba township, Shafer, Shafer township, Stacy, Taylors Falls.

Counties near Chisago 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: 1,124 samples in Chisago 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 Chisago County, up to 1,261 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.
USGS national arsenic model (Ayotte 2017): estimated share of 27,563 people on private wells in Chisago 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.
Minnesota Well Index: 7,949 well records in Chisago County, 7,676 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: 301 regulated sites located in Chisago 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.